000
FXUS63 KDTX 231109
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
709 AM EDT THU MAY 23 2013
.AVIATION...
//DISCUSSION...
CONDITIONS WILL RAPIDLY DETERIORATE TO MVFR THIS MORNING AS WINDS
TURN NORTHERLY BEHIND A COLD FRONT MAKING ITS WAY THROUGH SOUTHEAST
MICHIGAN. THE FRONT IS CURRENTLY BETWEEN FNT AND PTK AND SHOULD PASS
THROUGH PTK AROUND 12Z...AND THE METRO AIRPORTS AROUND 13Z. RAIN
SHOWERS COULD REDUCE CIGS TO IFR AT TIMES AS NORTH WINDS GUST TO 20
KNOTS. THE FRONT WILL CONTINUE MOVING SOUTH TONIGHT...AS APPROACHING
HIGH PRESSURE BRINGS DRY AIR AND VFR CONDITIONS TO THE TAF SITES
DURING THE EVENING HOURS.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILINGS BELOW 5000 FT BY 13Z...CONTINUING
THROUGH THE EARLY EVENING HOURS.
&&
.PREV DISCUSSION...ISSUED 352 AM EDT THU MAY 23 2013
SHORT TERM...TODAY AND TONIGHT
A SLOWLY SINKING COLD FRONT WILL BRING AN ABRUPT CHANGE IN
TEMPERATURES ACROSS SOUTHEAST MICHIGAN TODAY. IN CONTRAST TO SEVERAL
DAYS APPROACHING OR EXCEEDING 80 DEGREES...TODAYS HIGHS WILL ONLY
GET INTO THE 50S ACROSS THE NORTH...WITH 60S EXPECTED ACROSS THE
SOUTH. THE HIGHS REALIZED TODAY WILL OCCUR IN THE MORNING
HOURS...BEFORE THE PUSH OF COLD AIR PUSHES AFTERNOON TEMPERATURES
DOWN INTO THE 40S ACROSS THE NORTH AND INTO THE 50S ACROSS THE
SOUTH. IN ADDITION TO COOLING TEMPERATURES...THE FRONT WILL BRING
RAIN SHOWERS AND A BRISK NORTH WIND BEHIND IT DURING THE AFTERNOON.
OVERALL SOUTHEAST MICHIGAN IS IN FOR A WET...WINDY AND COOL DAY WITH
THE BEST WEATHER OCCURRING DURING THE EARLY MORNING HOURS.
THE PIECE OF GOOD NEWS TODAY IS THE THREAT FOR THUNDERSTORMS APPEARS
TO HAVE DIMINISHED TO THE POINT OF LEAVING THUNDER OUT OF THE
MORNING FORECAST AS MUCAPE VALUES STRUGGLE TO GET TO 100 J/KG AHEAD
OF THE APPROACHING COLD FRONT. DYNAMICS WILL BE EASY TO COME BY
TODAY AS THE LOW THAT HAS BEEN OUT TO OUR WEST FOR THE PAST SEVERAL
DAYS TRACKS THROUGH THE CENTRAL GREAT LAKES AS A POSITIVELY TILTED
TROUGH WITH SEVERAL EMBEDDED SHORTWAVES AS SHOWN ON THE WATER VAPOR
IMAGERY. A CROSS SECTION THROUGH MICHIGAN SHOWS ABUNDANT MOISTURE
AND FGEN FROM 925 MB TO 850 MB AS THE COLD FRONT SINKS
SOUTH...WARRANTING CATEGORICAL POPS AS THE FRONT TRACKS THROUGH
SOUTHEAST MICHIGAN TODAY.
THE FRONT WILL PUSH EAST EARLY THIS EVENING AS THE MID LEVEL TROUGH
BECOMES NEUTRALLY TILTED AND MOVES EAST WITH THE FRONT. HIGH
PRESSURE WILL BRING DRY AIR AND QUIET WEATHER TO THE CENTRAL GREAT
LAKES LATER TONIGHT AS 850 MB TEMPERATURES SINK TO AROUND ZERO
DEGREES. WITH CLEARING SKIES AND THE PUSH SOUTH OF THESE COLD
TEMPERATURES...SOME FROST IS POSSIBLE AWAY FROM THE GREAT LAKES AND
THE DETROIT METRO AREA AS LOW TEMPERATURES FALL INTO THE MID TO
UPPER 30S. CLOSER TO THE LAKES AND ACROSS THE METRO AREA LOWS ARE
EXPECTED TO GET DOWN TO AROUND 40. THE MAIN FACTOR INHIBITING
WIDESPREAD FREEZING TEMPERATURES WILL BE SURFACE WINDS AROUND 10 MPH
AS A TIGHT PRESSURE GRADIENT REMAINS BETWEEN THE DEPARTING LOW AND
THE HIGH BUILDING IN FROM THE NORTH.
LONG TERM...FRIDAY THROUGH WEDNESDAY
FAIRLY QUIET WEATHER THROUGH MOST OF THE EXTENDED FORECAST. A
BLOCKING PATTERN...UPPER LOWS OVER BOTH COASTS...WILL SET UP ACROSS
THE CONUS FOR THE HOLIDAY WEEKEND LOCKING US UNDER THE EASTERN EDGE
OF UPPER LEVEL RIDGE AND DIRECTLY UNDER BROAD AREA OF SFC HIGH
PRESSURE. PATTERN BREAKS DOWN BY MID WEEK AS EAST COAST TROUGH GETS
ABSORBED IN NORTHERN STREAM FLOW AND LIFTED INTO THE ATLANTIC.
MEANWHILE STRONG MIDLEVEL SHORTWAVE WILL SHOOT AROUND THE WEST COAST
TROUGH AND WILL BEGIN TO BREAK DOWN THE AMPLIFIED RIDGE. ONLY REAL
CHANCE OF PRECIP WILL COME WED/THURS AS THE SHORT WAVE WILL ATTEMPT
TO LIFT A WARM FRONT THROUGH THE AREA.
FRIDAY THROUGH SUNDAY WILL FEATURE A COOL DOME OF SURFACE HIGH
PRESSURE BUILDING SOUTH FROM CANADA WITH MIDLEVEL CONFLUENT FLOW.
FRIDAY WILL START OFF ON THE BREEZY SIDE AS WE FALL ON THE EASTERN
SIDE OF THE HIGH UNDER A DECENT NE/SW PRESSURE GRADIENT. THE
PERSISTENT FEED OF COOL AIR...850 MB TEMPS IN THE SINGLE DIGITS
THROUGH THE DAY...WILL KEEP DAYTIME HIGHS IN THE LOW 60S WHICH IS
ABOUT 10 DEGREES BELOW NORMAL. THE EXCEPTION WILL BE THE THUMB
REGION WHERE THE ONSHORE FLOW WILL KEEPS TEMPS IN THE LOW/MID 50S.
HEIGHTS WILL GRADUALLY RISE THROUGH THE WEEKEND. THIS COMBINED WITH
CLEAR SKIES AND DECREASING NORTHERLY FLOW WILL PRODUCE A WARMING
TREND THROUGH THE WEEKEND BY MONDAY.
FOR THE MIDDLE PART OF THE WEEK...THE AFOREMENTIONED SHORTWAVE WILL
EJECT OUT OF THE WEST COAST TROUGH AND TRACK UP ACROSS THE NORTHERN
PLAINS INTO ONTARIO. THIS WILL LIFT A WARM FRONT UP THROUGH THE
GREAT LAKES BRINGING MILD WESTERLY/SOUTHWESTERLY FLOW BACK TO SE MI
AND ALLOWING TEMPS TO JUMP BACK NEAR 80. MODELS DISAGREE WITH TIMING
OF THE FROPA AND AMOUNT OF MOISTURE ASSOCIATED WITH IT SO WENT WITH
LOW CHANCE/SLIGHT CHANCE POPS STARTING TUESDAY NIGHT FOR THE TIME
BEING.
MARINE...
A COLD FRONT SINKING SOUTH WILL CAUSE WINDS TO SHIFT TO THE NORTH
ACROSS ALL WATERS THIS MORNING...AS THE MAIN SURFACE LOW AND
TRAILING COLD FRONT PUSH OFF TO THE EAST. WINDS AND WAVES WILL
INCREASE GREATLY WITH THE ADVECTION OF COLD AND DRY AIR...LEADING TO
SMALL CRAFT ADVISORY CONDITIONS FOR ALL OF THE LAKE HURON NEARSHORE
WATERS AND LAKE ST. CLAIR. FURTHER SOUTH OFFSHORE FLOW WILL CAUSE
WINDS TO STAY BELOW CRITERIA FOR WESTERN LAKE ERIE. THEREFORE WILL
CONTINUE AND ISSUE SMALL CRAFT ADVISORIES FOR THESE ZONES TODAY AND
TONIGHT. ALTHOUGH WINDS MAY BRIEFLY REACH GALE FORCE ACROSS SOUTHERN
LAKE HURON THIS AFTERNOON...THE WINDOW APPEARS BRIEF ENOUGH AND WIND
SPEEDS MARGINAL ENOUGH TO AVOID HOISTING GALE WARNINGS FOR THIS
AFTERNOON. A CONTINUED NORTH WIND AND LONG FETCH ALONG LAKE HURON
WILL CONTINUE SMALL CRAFT CONDITIONS FOR THE LAKE HURON NEARSHORE
ZONES AND OUTER SAGINAW BAY AS WAVES REMAIN ELEVATED ON FRIDAY.
HIGH PRESSURE WILL BRING LOWER WINDS AND WAVES ACROSS THE CENTRAL
GREAT LAKES THIS WEEKEND...WITH CONDITIONS EXPECTED TO BE WELL BELOW
ANY HEADLINES.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...INNER SAGINAW BAY...UNTIL 8 PM THURSDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON...UNTIL 6 PM FRIDAY.
SMALL CRAFT ADVISORY...OUTER SAGINAW BAY...UNTIL NOON FRIDAY.
LAKE ST CLAIR...
SMALL CRAFT ADVISORY...FROM NOON THURSDAY TO MIDNIGHT FRIDAY.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....KURIMSKI
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 230752
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
352 AM EDT THU MAY 23 2013
.SHORT TERM...TODAY AND TONIGHT
A SLOWLY SINKING COLD FRONT WILL BRING AN ABRUPT CHANGE IN
TEMPERATURES ACROSS SOUTHEAST MICHIGAN TODAY. IN CONTRAST TO SEVERAL
DAYS APPROACHING OR EXCEEDING 80 DEGREES...TODAYS HIGHS WILL ONLY
GET INTO THE 50S ACROSS THE NORTH...WITH 60S EXPECTED ACROSS THE
SOUTH. THE HIGHS REALIZED TODAY WILL OCCUR IN THE MORNING
HOURS...BEFORE THE PUSH OF COLD AIR PUSHES AFTERNOON TEMPERATURES
DOWN INTO THE 40S ACROSS THE NORTH AND INTO THE 50S ACROSS THE
SOUTH. IN ADDITION TO COOLING TEMPERATURES...THE FRONT WILL BRING
RAIN SHOWERS AND A BRISK NORTH WIND BEHIND IT DURING THE AFTERNOON.
OVERALL SOUTHEAST MICHIGAN IS IN FOR A WET...WINDY AND COOL DAY WITH
THE BEST WEATHER OCCURRING DURING THE EARLY MORNING HOURS.
THE PIECE OF GOOD NEWS TODAY IS THE THREAT FOR THUNDERSTORMS APPEARS
TO HAVE DIMINISHED TO THE POINT OF LEAVING THUNDER OUT OF THE
MORNING FORECAST AS MUCAPE VALUES STRUGGLE TO GET TO 100 J/KG AHEAD
OF THE APPROACHING COLD FRONT. DYNAMICS WILL BE EASY TO COME BY
TODAY AS THE LOW THAT HAS BEEN OUT TO OUR WEST FOR THE PAST SEVERAL
DAYS TRACKS THROUGH THE CENTRAL GREAT LAKES AS A POSITIVELY TILTED
TROUGH WITH SEVERAL EMBEDDED SHORTWAVES AS SHOWN ON THE WATER VAPOR
IMAGERY. A CROSS SECTION THROUGH MICHIGAN SHOWS ABUNDANT MOISTURE
AND FGEN FROM 925 MB TO 850 MB AS THE COLD FRONT SINKS
SOUTH...WARRANTING CATEGORICAL POPS AS THE FRONT TRACKS THROUGH
SOUTHEAST MICHIGAN TODAY.
THE FRONT WILL PUSH EAST EARLY THIS EVENING AS THE MID LEVEL TROUGH
BECOMES NEUTRALLY TILTED AND MOVES EAST WITH THE FRONT. HIGH
PRESSURE WILL BRING DRY AIR AND QUIET WEATHER TO THE CENTRAL GREAT
LAKES LATER TONIGHT AS 850 MB TEMPERATURES SINK TO AROUND ZERO
DEGREES. WITH CLEARING SKIES AND THE PUSH SOUTH OF THESE COLD
TEMPERATURES...SOME FROST IS POSSIBLE AWAY FROM THE GREAT LAKES AND
THE DETROIT METRO AREA AS LOW TEMPERATURES FALL INTO THE MID TO
UPPER 30S. CLOSER TO THE LAKES AND ACROSS THE METRO AREA LOWS ARE
EXPECTED TO GET DOWN TO AROUND 40. THE MAIN FACTOR INHIBITING
WIDESPREAD FREEZING TEMPERATURES WILL BE SURFACE WINDS AROUND 10 MPH
AS A TIGHT PRESSURE GRADIENT REMAINS BETWEEN THE DEPARTING LOW AND
THE HIGH BUILDING IN FROM THE NORTH.
&&
.LONG TERM...FRIDAY THROUGH WEDNESDAY
FAIRLY QUIET WEATHER THROUGH MOST OF THE EXTENDED FORECAST. A
BLOCKING PATTERN...UPPER LOWS OVER BOTH COASTS...WILL SET UP ACROSS
THE CONUS FOR THE HOLIDAY WEEKEND LOCKING US UNDER THE EASTERN EDGE
OF UPPER LEVEL RIDGE AND DIRECTLY UNDER BROAD AREA OF SFC HIGH
PRESSURE. PATTERN BREAKS DOWN BY MID WEEK AS EAST COAST TROUGH GETS
ABSORBED IN NORTHERN STREAM FLOW AND LIFTED INTO THE ATLANTIC.
MEANWHILE STRONG MIDLEVEL SHORTWAVE WILL SHOOT AROUND THE WEST COAST
TROUGH AND WILL BEGIN TO BREAK DOWN THE AMPLIFIED RIDGE. ONLY REAL
CHANCE OF PRECIP WILL COME WED/THURS AS THE SHORT WAVE WILL ATTEMPT
TO LIFT A WARM FRONT THROUGH THE AREA.
FRIDAY THROUGH SUNDAY WILL FEATURE A COOL DOME OF SURFACE HIGH
PRESSURE BUILDING SOUTH FROM CANADA WITH MIDLEVEL CONFLUENT FLOW.
FRIDAY WILL START OFF ON THE BREEZY SIDE AS WE FALL ON THE EASTERN
SIDE OF THE HIGH UNDER A DECENT NE/SW PRESSURE GRADIENT. THE
PERSISTENT FEED OF COOL AIR...850 MB TEMPS IN THE SINGLE DIGITS
THROUGH THE DAY...WILL KEEP DAYTIME HIGHS IN THE LOW 60S WHICH IS
ABOUT 10 DEGREES BELOW NORMAL. THE EXCEPTION WILL BE THE THUMB
REGION WHERE THE ONSHORE FLOW WILL KEEPS TEMPS IN THE LOW/MID 50S.
HEIGHTS WILL GRADUALLY RISE THROUGH THE WEEKEND. THIS COMBINED WITH
CLEAR SKIES AND DECREASING NORTHERLY FLOW WILL PRODUCE A WARMING
TREND THROUGH THE WEEKEND BY MONDAY.
FOR THE MIDDLE PART OF THE WEEK...THE AFOREMENTIONED SHORTWAVE WILL
EJECT OUT OF THE WEST COAST TROUGH AND TRACK UP ACROSS THE NORTHERN
PLAINS INTO ONTARIO. THIS WILL LIFT A WARM FRONT UP THROUGH THE
GREAT LAKES BRINGING MILD WESTERLY/SOUTHWESTERLY FLOW BACK TO SE MI
AND ALLOWING TEMPS TO JUMP BACK NEAR 80. MODELS DISAGREE WITH TIMING
OF THE FROPA AND AMOUNT OF MOISTURE ASSOCIATED WITH IT SO WENT WITH
LOW CHANCE/SLIGHT CHANCE POPS STARTING TUESDAY NIGHT FOR THE TIME
BEING.
&&
.MARINE...
A COLD FRONT SINKING SOUTH WILL CAUSE WINDS TO SHIFT TO THE NORTH
ACROSS ALL WATERS THIS MORNING...AS THE MAIN SURFACE LOW AND
TRAILING COLD FRONT PUSH OFF TO THE EAST. WINDS AND WAVES WILL
INCREASE GREATLY WITH THE ADVECTION OF COLD AND DRY AIR...LEADING TO
SMALL CRAFT ADVISORY CONDITIONS FOR ALL OF THE LAKE HURON NEARSHORE
WATERS AND LAKE ST. CLAIR. FURTHER SOUTH OFFSHORE FLOW WILL CAUSE
WINDS TO STAY BELOW CRITERIA FOR WESTERN LAKE ERIE. THEREFORE WILL
CONTINUE AND ISSUE SMALL CRAFT ADVISORIES FOR THESE ZONES TODAY AND
TONIGHT. ALTHOUGH WINDS MAY BRIEFLY REACH GALE FORCE ACROSS SOUTHERN
LAKE HURON THIS AFTERNOON...THE WINDOW APPEARS BRIEF ENOUGH AND WIND
SPEEDS MARGINAL ENOUGH TO AVOID HOISTING GALE WARNINGS FOR THIS
AFTERNOON. A CONTINUED NORTH WIND AND LONG FETCH ALONG LAKE HURON
WILL CONTINUE SMALL CRAFT CONDITIONS FOR THE LAKE HURON NEARSHORE
ZONES AND OUTER SAGINAW BAY AS WAVES REMAIN ELEVATED ON FRIDAY.
HIGH PRESSURE WILL BRING LOWER WINDS AND WAVES ACROSS THE CENTRAL
GREAT LAKES THIS WEEKEND...WITH CONDITIONS EXPECTED TO BE WELL BELOW
ANY HEADLINES.
&&
.AVIATION...ISSUED 1210 AM EDT THU MAY 23 2013
//DISCUSSION...
PREDOMINANTLY VFR CONDITIONS WILL PREVAIL THROUGH THE VERY EARLY
MORNING HOURS OUTSIDE OF A STRAY SHOWER OR TWO ACROSS THE DETROIT
AREA TAF SITES. THE COMBINATION OF LOW-LEVEL COLD ADVECTION AND
WEAKENING MOISTURE TRANSPORT INTO A SLOW-MOVING FRONTAL ZONE WILL
THEN RESULT IN LIGHT SHOWERS PUSHING SOUTH AND A DETERIORATION OF
CONDITIONS TO AT LEAST MVFR FROM NW TO SE BY APPROX 10Z. LIGHT SW
FLOW WILL GIVE WAY TO GUSTY NORTH WINDS IN THE WAKE OF THE FRONTAL
PASSAGE.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILINGS BELOW 5KFT BY 12Z
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...INNER SAGINAW BAY...UNTIL 8 PM THURSDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON...FROM 8 AM THURSDAY TO 6 PM FRIDAY.
SMALL CRAFT ADVISORY...OUTER SAGINAW BAY...FROM 8 AM THURSDAY TO
NOON FRIDAY.
LAKE ST CLAIR...
SMALL CRAFT ADVISORY...FROM NOON THURSDAY TO MIDNIGHT FRIDAY.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
AVIATION.....JVC
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 230410
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1210 AM EDT THU MAY 23 2013
.AVIATION...
//DISCUSSION...
PREDOMINANTLY VFR CONDITIONS WILL PREVAIL THROUGH THE VERY EARLY
MORNING HOURS OUTSIDE OF A STRAY SHOWER OR TWO ACROSS THE DETROIT
AREA TAF SITES. THE COMBINATION OF LOW-LEVEL COLD ADVECTION AND
WEAKENING MOISTURE TRANSPORT INTO A SLOW-MOVING FRONTAL ZONE WILL
THEN RESULT IN LIGHT SHOWERS PUSHING SOUTH AND A DETERIORATION OF
CONDITIONS TO AT LEAST MVFR FROM NW TO SE BY APPROX 10Z. LIGHT SW
FLOW WILL GIVE WAY TO GUSTY NORTH WINDS IN THE WAKE OF THE FRONTAL
PASSAGE.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILINGS BELOW 5KFT BY 12Z
&&
.PREV DISCUSSION...ISSUED 848 PM EDT WED MAY 22 2013
UPDATE...
TONIGHT`S PORTION OF THE GRIDDED FORECAST HAS BEEN UPDATED TO
INCORPORATE RECENT TRENDS AND LATEST HIGH-RESOLUTION NWP INFORMATION
NOW THAT THE DAY`S CONVECTION HAS ESSENTIALLY RUN ITS COURSE,
INCLUDING CONVECTION ACROSS SE MICHIGAN. WITH THE LOSS OF DIURNAL
HEATING, EXISTING ACTIVITY WILL STEADILY DECREASE IN COVERAGE AND
INTENSITY OVER THE NEXT COUPLE OF HOURS. CONFIDENCE IS HIGH THAT THE
SEVERE THREAT FOR THE EVENING HAS ENDED GIVEN THAT WINDS ASSOCIATED
WITH THE MOST ORGANIZED CONVECTIVE STRUCTURE OF THE EVENING IN
LENAWEE/MONROE COUNTIES WERE UNABLE TO PENETRATE THE DEVELOPING
STABLE LAYER. POPS HAVE THEREFORE BEEN TRIMMED BACK SIGNIFICANTLY WITH
NOTHING MORE THAN A PASSING SHOWER EXPECTED THROUGH LATE TONIGHT.
THE EXCEPTION WILL BE TOWARD THE MI/OH BORDER WHERE DIURNALLY
ENHANCED ACTIVITY OVER EASTERN ILLINOIS/WESTERN INDIANA AT 00Z MAY
BE SUFFICIENTLY MAINTAINED BY FORCING FOR ASCENT AHEAD OF THE
PRIMARY TROUGH AXIS TO GRAZE SOUTHERN AREAS BETWEEN 03-09Z. THE
REMAINDER OF THE FORECAST THEN LOOKS ON TRACK. WEAKENING MOISTURE
TRANSPORT WILL CONTINUE TO FUEL SHOWERS WITHIN A SLOW-MOVING
BAROCLINIC ZONE THAT WILL SAG INTO THE NW CWA BY EARLY MORNING.
PREV DISCUSSION...ISSUED 325 PM EDT WED MAY 22 2013
SHORT TERM...THIS EVENING AND TONIGHT
BROAD UPPER LOW OVER MN/IA THIS AFTERNOON CONTINUES TO PIVOT
SHORTWAVE ENERGY CYCLONICALLY INTO LAKE MICHIGAN AND SW PORTIONS OF
THE STATE. A WEAKER EXTENSION OF THAT ENERGY IS SEEN ON THE IR
SATELLITE AS FAR SE AS DAY/CMH. THAT FORCING WILL MAKE ITS WAY INTO
OUR CWA THIS AFTERNOON. THERE ARE SOME BREAKS IN THE CLOUDS ACROSS
FAR SRN MI PRESENTLY AND THIS WILL HELP DESTABILIZE THE BOUNDARY
LAYER AS WE WAIT FOR MORE FORCING IN THE WAY OF COLD FRONT/TRIPLE
POINT SFC FEATURES TO ADVANCE. WARM FRONT IS NOW DRAPED ACROSS THE
THUMB AREA AS SEEN IN SFC OBS. ALSO OBSERVED ON DTX RADAR ARE
SEVERAL GRAVITY WAVES (SEEN AS FINE LINES A BIT THICKER THAN OUTFLOW
BOUNDARIES) LIKELY PERTURBATING FROM THE PARENT UPPER LOW AND JET
STREAM DYNAMICS.
WITH THE ABOVE-MENTIONED FORCING MECHANISMS WE ARE STILL ONLY
DEALING WITH THE PREVIOUSLY ADVERTISED 500 J/KG OF CAPE. ADDL SFC
HEATING WILL SQUEEZE 1 TO 1.5 J/G OUT OF A MODIFIED SOUNDING...BUT
TO THIS POINT THE CELLS THAT POPPED UP IN THIS AIRMASS HAVE NOT HAD
STRONG UPDRAFTS. WE DO HAVE A GOOD AMOUNT OF SHEER AS OBSERVED IN AN
18Z DTX SOUNDING...MOSTLY AS SPEED INCREASE WITH HEIGHT, BUT ONLY
SLIGHT VEERING.
ALSO AMONG MARGINAL INGREDIENTS IS MOISTURE CONTENT THAT HOVERS
AROUND MID 60S DEWPOINT TEMPERATURES AND 1.5 INCHES PW. SLIGHT RISK
FOR SEVERE IS STILL WARRANTED AS THE EVOLUTION OF OUR ENVIRONMENT
WILL CHANGE THESE INGREDIENTS WITH TIME. POP-UP CELLS ACROSS SRN MI
AND NRN IN WILL TELL THE STORY FOR FUTURE DEVELOPMENT. WITH THE HIGH
SHEER SETUP, WOULD NOT BE SURPRISED TO SEE WEAK TORNADIC ACTIVITY,
AND ALSO WIND DAMAGE IN ANY LONGER LIVED SINGLE CELLS OR BOWED LINE
SEGMENT STORMS. LIMITED UPDRAFT STRENGTH WILL PROBABLY KEEP HAIL
SIZE ON A SMALLER SCALE.
SEVERE POTENTIAL DROPS OFF AFTER 00Z AS SRN 7 COUNTIES WILL RECOVER
WITH A DRY PERIOD UNDER OVERCAST SKIES. SAGINAW VALLEY REMAINS IN THE
FRONTAL ZONE AS THE UPPER LOW PIVOTS EASTWARD OVERNIGHT AND WILL
HOLD A CATEGORICAL POP THERE...FADED TO LIKELY SOUTH OF THERE.
LONG TERM...THURSDAY THROUGH TUESDAY
THE HIGH AMPLITUDE AND RELATIVELY STATIC LONGWAVE PATTERN OF RECENT
DAYS MARKED BY A CLOSED MID LEVEL CIRCULATION MEANDERING OVER THE
UPPER MS VALLEY WILL FINALLY SEE SOME FORWARD PROGRESS THROUGH THE
END OF THE WEEK. THE EXPECTED EASTWARD PROPAGATION OF THE ENTIRE
LONGWAVE TROUGH STRUCTURE THROUGH SOUTHEAST MICHIGAN ON THURSDAY
WILL UNFOLD AS EXTENSIVE UPPER RIDGING TAKES RESIDENCE THROUGH THE
PLAINS. THE ATTENDANT SURFACE COLD FRONTAL BOUNDARY WILL BE
MIGRATING SOUTHEASTWARD AND THROUGH LOWER MICHIGAN BY EARLY
THURSDAY. GREATEST FORCING WILL ALIGN ALONG THE 850-925 MB FRONTAL
SLOPE...WITH A PERIOD OF HEIGHTENED MID LEVEL FGEN FORCING AND
DEFORMATION EMERGING LOCALLY AS A TRAILING SHARP MID LEVEL SHEAR
AXIS NOW SEEN ON WATER VAPOR STREAMING THROUGH WESTERN ONTARIO
SWEEPS OVER THE FRONTAL ZONE. LOW LEVEL LAPSE RATES STEEPEN
MODESTLY BELOW THIS LAYER IN RESPONSE TO DEVELOPING WEAK COLD AIR
ADVECTION. GIVEN A SUFFICIENTLY DEEP MOISTURE PROFILE...THIS
ENVIRONMENT WILL SUPPORT THE MAINTENANCE/EXPANSION IN
SHOWER ACTIVITY AS THE FRONT WORKS THROUGH ON THURSDAY. THE
COMBINATION OF THE ADVECTIVE PROCESS AND THE LIMITED HEATING
POTENTIAL UNDER SUBSTANTIAL CLOUD COVER WILL CERTAINLY RESTRICT
THE TEMPERATURE RESPONSE...HIGH TEMPERATURES LIKELY CONFINED TO
WITHIN SEVERAL DEGREE OF MORNING LOWS. THIS TRANSLATES INTO A
SHARPER NORTH TO SOUTH TEMPERATURES GRADIENT...READINGS RANGING
FROM AROUND 50 IN THE THUMB TO MID 60S NEAR THE OHIO BORDER.
STEADY COLD/DRY AIR ADVECTION WILL PROVIDE A DEFINITIVE BACK EDGE TO
THIS MOISTURE AXIS WITH A PROGRESSIVE CLEARING TREND COMMENCING FROM
MID AFTERNOON INTO THE EVENING HOURS FROM NORTHWEST TO SOUTHEAST.
CRISP CP AIRMASS WILL FIRMLY SETTLE IN OVERNIGHT WITHIN DEEPENING
NORTHERLY FLOW ALONG THE EASTERN EDGE OF EXPANDING HIGH PRESSURE
OVER THE UPPER MIDWEST. 850 MB TEMPERATURES STILL LOOK TO BOTTOM
OUT AROUND THE FREEZING MARK BY 12Z FRIDAY MORNING. BOUNDARY
LAYER WILL LIKELY REMAIN MIXED ENOUGH TO PREVENT A MORE PRONOUNCED
RADIATIONAL COOLING ENVIRONMENT...BUT THE GENERAL STRENGTH OF THIS
AIRMASS WILL SUPPORT LOWS OF UPPER 30S FOR ALL LOCALES OUTSIDE OF
THE DETROIT HEAT ISLAND INFLUENCE. POCKETS OF PATCHY FROST NOT OUT
OF THE QUESTION...ALTHOUGH A DRYING LOW LEVEL COLUMN AND THE
QUESTION OF LINGERING MIXING REMAIN MITIGATING FACTORS TO POTENTIAL
FORMATION.
EXTENDED STRETCH OF RELATIVELY BENIGN WEATHER CONDITIONS WILL EXIST
FROM FRIDAY RIGHT THROUGH NEXT WEEKEND AS THE REGION SETTLES INTO
DRY CONFLUENT NORTHWEST FLOW ANCHORED OVER GENERAL SURFACE RIDGING.
SHORTWAVE ENERGY AND ANY ASSOCIATED WARM/MOIST AIR ADVECTION
COMPONENT ROUNDING THE APEX OF THE PREVAILING UPPER RIDGE DRAPED
OVER THE PLAINS WILL TEND TO ARC DOWN THE PRIMARY INSTABILITY
GRADIENT CONFINED WELL TO THE SOUTHWEST. SIMPLE AIRMASS
MODIFICATION DURING THIS TIME UNDER GENERAL MID LEVEL HEIGHT RISES
AND PLENTY OF INSOLATION IN THE WAKE OF THE DEPARTING LONGWAVE
TROUGH. HIGHS BACK INTO THE MIDDLE 60S FOR INLAND LOCATIONS BY
THE WEEKEND...STILL HOLDING A CATEGORY COOLER ALONG THE THUMB AND
OTHER IMMEDIATE NEARSHORE LOCALES.
MARINE...
AN UNSTABLE ENVIRONMENT THIS EVENING WILL BRING A CHANCE OF STRONG
TO SEVERE THUNDERSTORMS THROUGH 8PM. AFTER THAT TIME LINGERING
THUNDERSHOWERS ARE POSSIBLE. FOG WILL AGAIN BE POSSIBLE OUT AHEAD OF
THE FRONTAL ZONE...MAINLY SOUTHERN HALF OF LAKE HURON OVERNIGHT.
WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS BY THURSDAY
MORNING...AS THE MAIN SURFACE LOW AND TRAILING COLD FRONT PUSH OFF
TO THE EAST. WINDS AND WAVES WILL INCREASE GREATLY WITH THE
ADVECTION OF COLD AND DRY AIR...AND THIS LEAD TO ISSUANCE OF A SMALL
CRAFT ADVISORY FOR MUCH OF NEARSHORE LAKE HURON. HIGH PRESSURE WILL
BUILD IN ACROSS THE GREAT LAKES ON FRIDAY...BRINGING QUIET WEATHER
AND COOLER TEMPERATURES TO THE REGION.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...INNER SAGINAW BAY...FROM 6 AM THURSDAY TO 2
PM THURSDAY.
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON INCLUDING OUTER SAGINAW BAY...FROM 10 AM THURSDAY TO 10
PM THURSDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....JVC
UPDATE.......JVC
SHORT TERM...MM
LONG TERM....MR
MARINE.......MM
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 230050 CCA
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
848 PM EDT WED MAY 22 2013
.UPDATE...
TONIGHT`S PORTION OF THE GRIDDED FORECAST HAS BEEN UPDATED TO
INCORPORATE RECENT TRENDS AND LATEST HIGH-RESOLUTION NWP INFORMATION
NOW THAT THE DAY`S CONVECTION HAS ESSENTIALLY RUN ITS COURSE,
INCLUDING CONVECTION ACROSS SE MICHIGAN. WITH THE LOSS OF DIURNAL
HEATING, EXISTING ACTIVITY WILL STEADILY DECREASE IN COVERAGE AND
INTENSITY OVER THE NEXT COUPLE OF HOURS. CONFIDENCE IS HIGH THAT THE
SEVERE THREAT FOR THE EVENING HAS ENDED GIVEN THAT WINDS ASSOCIATED
WITH THE MOST ORGANIZED CONVECTIVE STRUCTURE OF THE EVENING IN
LENAWEE/MONROE COUNTIES WERE UNABLE TO PENETRATE THE DEVELOPING
STABLE LAYER. POPS HAVE THEREFORE BEEN TRIMMED BACK SIGNIFICANTLY WITH
NOTHING MORE THAN A PASSING SHOWER EXPECTED THROUGH LATE TONIGHT.
THE EXCEPTION WILL BE TOWARD THE MI/OH BORDER WHERE DIURNALLY
ENHANCED ACTIVITY OVER EASTERN ILLINOIS/WESTERN INDIANA AT 00Z MAY
BE SUFFICIENTLY MAINTAINED BY FORCING FOR ASCENT AHEAD OF THE
PRIMARY TROUGH AXIS TO GRAZE SOUTHERN AREAS BETWEEN 03-09Z. THE
REMAINDER OF THE FORECAST THEN LOOKS ON TRACK. WEAKENING MOISTURE
TRANSPORT WILL CONTINUE TO FUEL SHOWERS WITHIN A SLOW-MOVING
BAROCLINIC ZONE THAT WILL SAG INTO THE NW CWA BY EARLY MORNING.
&&
.AVIATION...ISSUED 707 PM EDT WED MAY 22 2013
//DISCUSSION...
ACTIVE AREAS OF SHOWERS AND A FEW TSTORMS ON KDTX RADAR WILL
CONTINUE TO DECREASE IN INTENSITY AND COVERAGE OVER THE NEXT FEW
HOURS AS DIURNAL INSTABILITY IS LOST. THE POTENTIAL EXCEPTION WILL
BE THE CLUSTER OF THUNDERSTORMS SEEN LEAVING NE INDIANA AND ENTERING
SE MICHIGAN AT APPROX 2300Z THIS EVENING. THE ORGANIZED NATURE OF
THESE STORMS SUGGESTS THAT THEY WILL AT LEAST HAVE THE POTENTIAL TO
HOLD TOGETHER LONG ENOUGH TO AFFECT THE DETROIT AREA AIRFIELDS OF
KDTW/KYIP DURING THE FIRST HOUR OR SO OF THE TAF PERIOD. A
PREVAILING FORECAST GROUP WILL BE INCLUDED TO CONVEY BEST IDEA OF
TIMING WITH FURTHER AMDS ISSUED IF NECESSARY TO ACCOUNT FOR LATEST
TRENDS.
BY THURSDAY MORNING, THE COMBINATION OF LOW-LEVEL COLD ADVECTION AND
WEAKENING MOISTURE TRANSPORT INTO A SLOW-MOVING FRONTAL ZONE WILL
RESULT IN LIGHT RAINFALL AND A DETERIORATION TO MVFR CONDITIONS THAT
WILL PERSIST WELL INTO THURSDAY AFTERNOON. RAPID CLEARING IS
EXPECTED NEAR OR SLIGHTLY AFTER 00Z FRI AS HIGH PRESSURE AND DRY
NORTHERLY FLOW SETTLE INTO THE REGION.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE THAT A THUNDERSTORM WILL IMPACT KDTW AIRSPACE PRIOR
TO 02Z.
* HIGH CONFIDENCE IN CEILINGS BELOW 5000 FEET BY 12Z
&&
.PREV DISCUSSION...ISSUED 325 PM EDT WED MAY 22 2013
SHORT TERM...THIS EVENING AND TONIGHT
BROAD UPPER LOW OVER MN/IA THIS AFTERNOON CONTINUES TO PIVOT
SHORTWAVE ENERGY CYCLONICALLY INTO LAKE MICHIGAN AND SW PORTIONS OF
THE STATE. A WEAKER EXTENSION OF THAT ENERGY IS SEEN ON THE IR
SATELLITE AS FAR SE AS DAY/CMH. THAT FORCING WILL MAKE ITS WAY INTO
OUR CWA THIS AFTERNOON. THERE ARE SOME BREAKS IN THE CLOUDS ACROSS
FAR SRN MI PRESENTLY AND THIS WILL HELP DESTABILIZE THE BOUNDARY
LAYER AS WE WAIT FOR MORE FORCING IN THE WAY OF COLD FRONT/TRIPLE
POINT SFC FEATURES TO ADVANCE. WARM FRONT IS NOW DRAPED ACROSS THE
THUMB AREA AS SEEN IN SFC OBS. ALSO OBSERVED ON DTX RADAR ARE
SEVERAL GRAVITY WAVES (SEEN AS FINE LINES A BIT THICKER THAN OUTFLOW
BOUNDARIES) LIKELY PERTURBATING FROM THE PARENT UPPER LOW AND JET
STREAM DYNAMICS.
WITH THE ABOVE-MENTIONED FORCING MECHANISMS WE ARE STILL ONLY
DEALING WITH THE PREVIOUSLY ADVERTISED 500 J/KG OF CAPE. ADDL SFC
HEATING WILL SQUEEZE 1 TO 1.5 J/G OUT OF A MODIFIED SOUNDING...BUT
TO THIS POINT THE CELLS THAT POPPED UP IN THIS AIRMASS HAVE NOT HAD
STRONG UPDRAFTS. WE DO HAVE A GOOD AMOUNT OF SHEER AS OBSERVED IN AN
18Z DTX SOUNDING...MOSTLY AS SPEED INCREASE WITH HEIGHT, BUT ONLY
SLIGHT VEERING.
ALSO AMONG MARGINAL INGREDIENTS IS MOISTURE CONTENT THAT HOVERS
AROUND MID 60S DEWPOINT TEMPERATURES AND 1.5 INCHES PW. SLIGHT RISK
FOR SEVERE IS STILL WARRANTED AS THE EVOLUTION OF OUR ENVIRONMENT
WILL CHANGE THESE INGREDIENTS WITH TIME. POP-UP CELLS ACROSS SRN MI
AND NRN IN WILL TELL THE STORY FOR FUTURE DEVELOPMENT. WITH THE HIGH
SHEER SETUP, WOULD NOT BE SURPRISED TO SEE WEAK TORNADIC ACTIVITY,
AND ALSO WIND DAMAGE IN ANY LONGER LIVED SINGLE CELLS OR BOWED LINE
SEGMENT STORMS. LIMITED UPDRAFT STRENGTH WILL PROBABLY KEEP HAIL
SIZE ON A SMALLER SCALE.
SEVERE POTENTIAL DROPS OFF AFTER 00Z AS SRN 7 COUNTIES WILL RECOVER
WITH A DRY PERIOD UNDER OVERCAST SKIES. SAGINAW VALLEY REMAINS IN THE
FRONTAL ZONE AS THE UPPER LOW PIVOTS EASTWARD OVERNIGHT AND WILL
HOLD A CATEGORICAL POP THERE...FADED TO LIKELY SOUTH OF THERE.
LONG TERM...THURSDAY THROUGH TUESDAY
THE HIGH AMPLITUDE AND RELATIVELY STATIC LONGWAVE PATTERN OF RECENT
DAYS MARKED BY A CLOSED MID LEVEL CIRCULATION MEANDERING OVER THE
UPPER MS VALLEY WILL FINALLY SEE SOME FORWARD PROGRESS THROUGH THE
END OF THE WEEK. THE EXPECTED EASTWARD PROPAGATION OF THE ENTIRE
LONGWAVE TROUGH STRUCTURE THROUGH SOUTHEAST MICHIGAN ON THURSDAY
WILL UNFOLD AS EXTENSIVE UPPER RIDGING TAKES RESIDENCE THROUGH THE
PLAINS. THE ATTENDANT SURFACE COLD FRONTAL BOUNDARY WILL BE
MIGRATING SOUTHEASTWARD AND THROUGH LOWER MICHIGAN BY EARLY
THURSDAY. GREATEST FORCING WILL ALIGN ALONG THE 850-925 MB FRONTAL
SLOPE...WITH A PERIOD OF HEIGHTENED MID LEVEL FGEN FORCING AND
DEFORMATION EMERGING LOCALLY AS A TRAILING SHARP MID LEVEL SHEAR
AXIS NOW SEEN ON WATER VAPOR STREAMING THROUGH WESTERN ONTARIO
SWEEPS OVER THE FRONTAL ZONE. LOW LEVEL LAPSE RATES STEEPEN
MODESTLY BELOW THIS LAYER IN RESPONSE TO DEVELOPING WEAK COLD AIR
ADVECTION. GIVEN A SUFFICIENTLY DEEP MOISTURE PROFILE...THIS
ENVIRONMENT WILL SUPPORT THE MAINTENANCE/EXPANSION IN
SHOWER ACTIVITY AS THE FRONT WORKS THROUGH ON THURSDAY. THE
COMBINATION OF THE ADVECTIVE PROCESS AND THE LIMITED HEATING
POTENTIAL UNDER SUBSTANTIAL CLOUD COVER WILL CERTAINLY RESTRICT
THE TEMPERATURE RESPONSE...HIGH TEMPERATURES LIKELY CONFINED TO
WITHIN SEVERAL DEGREE OF MORNING LOWS. THIS TRANSLATES INTO A
SHARPER NORTH TO SOUTH TEMPERATURES GRADIENT...READINGS RANGING
FROM AROUND 50 IN THE THUMB TO MID 60S NEAR THE OHIO BORDER.
STEADY COLD/DRY AIR ADVECTION WILL PROVIDE A DEFINITIVE BACK EDGE TO
THIS MOISTURE AXIS WITH A PROGRESSIVE CLEARING TREND COMMENCING FROM
MID AFTERNOON INTO THE EVENING HOURS FROM NORTHWEST TO SOUTHEAST.
CRISP CP AIRMASS WILL FIRMLY SETTLE IN OVERNIGHT WITHIN DEEPENING
NORTHERLY FLOW ALONG THE EASTERN EDGE OF EXPANDING HIGH PRESSURE
OVER THE UPPER MIDWEST. 850 MB TEMPERATURES STILL LOOK TO BOTTOM
OUT AROUND THE FREEZING MARK BY 12Z FRIDAY MORNING. BOUNDARY
LAYER WILL LIKELY REMAIN MIXED ENOUGH TO PREVENT A MORE PRONOUNCED
RADIATIONAL COOLING ENVIRONMENT...BUT THE GENERAL STRENGTH OF THIS
AIRMASS WILL SUPPORT LOWS OF UPPER 30S FOR ALL LOCALES OUTSIDE OF
THE DETROIT HEAT ISLAND INFLUENCE. POCKETS OF PATCHY FROST NOT OUT
OF THE QUESTION...ALTHOUGH A DRYING LOW LEVEL COLUMN AND THE
QUESTION OF LINGERING MIXING REMAIN MITIGATING FACTORS TO POTENTIAL
FORMATION.
EXTENDED STRETCH OF RELATIVELY BENIGN WEATHER CONDITIONS WILL EXIST
FROM FRIDAY RIGHT THROUGH NEXT WEEKEND AS THE REGION SETTLES INTO
DRY CONFLUENT NORTHWEST FLOW ANCHORED OVER GENERAL SURFACE RIDGING.
SHORTWAVE ENERGY AND ANY ASSOCIATED WARM/MOIST AIR ADVECTION
COMPONENT ROUNDING THE APEX OF THE PREVAILING UPPER RIDGE DRAPED
OVER THE PLAINS WILL TEND TO ARC DOWN THE PRIMARY INSTABILITY
GRADIENT CONFINED WELL TO THE SOUTHWEST. SIMPLE AIRMASS
MODIFICATION DURING THIS TIME UNDER GENERAL MID LEVEL HEIGHT RISES
AND PLENTY OF INSOLATION IN THE WAKE OF THE DEPARTING LONGWAVE
TROUGH. HIGHS BACK INTO THE MIDDLE 60S FOR INLAND LOCATIONS BY
THE WEEKEND...STILL HOLDING A CATEGORY COOLER ALONG THE THUMB AND
OTHER IMMEDIATE NEARSHORE LOCALES.
MARINE...
AN UNSTABLE ENVIRONMENT THIS EVENING WILL BRING A CHANCE OF STRONG
TO SEVERE THUNDERSTORMS THROUGH 8PM. AFTER THAT TIME LINGERING
THUNDERSHOWERS ARE POSSIBLE. FOG WILL AGAIN BE POSSIBLE OUT AHEAD OF
THE FRONTAL ZONE...MAINLY SOUTHERN HALF OF LAKE HURON OVERNIGHT.
WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS BY THURSDAY
MORNING...AS THE MAIN SURFACE LOW AND TRAILING COLD FRONT PUSH OFF
TO THE EAST. WINDS AND WAVES WILL INCREASE GREATLY WITH THE
ADVECTION OF COLD AND DRY AIR...AND THIS LEAD TO ISSUANCE OF A SMALL
CRAFT ADVISORY FOR MUCH OF NEARSHORE LAKE HURON. HIGH PRESSURE WILL
BUILD IN ACROSS THE GREAT LAKES ON FRIDAY...BRINGING QUIET WEATHER
AND COOLER TEMPERATURES TO THE REGION.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON INCLUDING OUTER SAGINAW BAY...FROM 10 AM THURSDAY TO 10
PM THURSDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......JVC
AVIATION.....JVC
SHORT TERM...MM
LONG TERM....MR
MARINE.......MM
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 230048
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
848 PM EDT WED MAY 22 2013
.UPDATE...
TONIGHT`S PORTION OF THE GRIDDED FORECAST HAS BEEN UPDATED TO
INCORPORATE RECENT TRENDS AND LATEST HIGH-RESOLUTION NWP INFORMATION
NOW THAT THE DAY`S CONVECTION HAS ESSENTIALLY RUN ITS COURSE,
INCLUDING CONVECTION ACROSS SE MICHIGAN. WITH THE LOSS OF DIURNAL
HEATING, EXISTING ACTIVITY WILL STEADILY DECREASE IN COVERAGE AND
INTENSITY OVER THE NEXT COUPLE OF HOURS. CONFIDENCE IS HIGH THAT THE
SEVERE THREAT FOR THE EVENING HAS ENDED GIVEN THAT WINDS ASSOCIATED
WITH THE MOST ORGANIZED CONVECTIVE STRUCTURE OF THE EVENING IN
LENAWEE/MONROE COUNTIES WERE UNABLE TO PENETRATE THE DEVELOPING
STABLE LAYER. POPS HAVE THEREFORE BEEN TRIMMED BACK SIGNIFICANT WITH
NOTHING MORE THAN A PASSING SHOWER EXPECTED THROUGH LATE TONIGHT.
THE EXCEPTION WILL BE TOWARD THE MI/OH BORDER WHERE DIURNALLY
ENHANCED ACTIVITY OVER EASTERN ILLINOIS/WESTERN INDIANA AT 00Z MAY
BE SUFFICIENTLY MAINTAINED BY FORCING FOR ASCENT AHEAD OF THE
PRIMARY TROUGH AXIS TO GRAZE SOUTHERN AREAS BETWEEN 03-09Z. THE
REMAINDER OF THE FORECAST THEN LOOKS ON TRACK. WEAKENING MOISTURE
TRANSPORT WILL CONTINUE TO FUEL SHOWERS WITHIN A SLOW-MOVING
BAROCLINIC ZONE THAT WILL BE SAGGING INTO THE NW CWA BY EARLY
MORNING.
&&
.AVIATION...ISSUED 707 PM EDT WED MAY 22 2013
//DISCUSSION...
ACTIVE AREAS OF SHOWERS AND A FEW TSTORMS ON KDTX RADAR WILL
CONTINUE TO DECREASE IN INTENSITY AND COVERAGE OVER THE NEXT FEW
HOURS AS DIURNAL INSTABILITY IS LOST. THE POTENTIAL EXCEPTION WILL
BE THE CLUSTER OF THUNDERSTORMS SEEN LEAVING NE INDIANA AND ENTERING
SE MICHIGAN AT APPROX 2300Z THIS EVENING. THE ORGANIZED NATURE OF
THESE STORMS SUGGESTS THAT THEY WILL AT LEAST HAVE THE POTENTIAL TO
HOLD TOGETHER LONG ENOUGH TO AFFECT THE DETROIT AREA AIRFIELDS OF
KDTW/KYIP DURING THE FIRST HOUR OR SO OF THE TAF PERIOD. A
PREVAILING FORECAST GROUP WILL BE INCLUDED TO CONVEY BEST IDEA OF
TIMING WITH FURTHER AMDS ISSUED IF NECESSARY TO ACCOUNT FOR LATEST
TRENDS.
BY THURSDAY MORNING, THE COMBINATION OF LOW-LEVEL COLD ADVECTION AND
WEAKENING MOISTURE TRANSPORT INTO A SLOW-MOVING FRONTAL ZONE WILL
RESULT IN LIGHT RAINFALL AND A DETERIORATION TO MVFR CONDITIONS THAT
WILL PERSIST WELL INTO THURSDAY AFTERNOON. RAPID CLEARING IS
EXPECTED NEAR OR SLIGHTLY AFTER 00Z FRI AS HIGH PRESSURE AND DRY
NORTHERLY FLOW SETTLE INTO THE REGION.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE THAT A THUNDERSTORM WILL IMPACT KDTW AIRSPACE PRIOR
TO 02Z.
* HIGH CONFIDENCE IN CEILINGS BELOW 5000 FEET BY 12Z
&&
.PREV DISCUSSION...ISSUED 325 PM EDT WED MAY 22 2013
SHORT TERM...THIS EVENING AND TONIGHT
BROAD UPPER LOW OVER MN/IA THIS AFTERNOON CONTINUES TO PIVOT
SHORTWAVE ENERGY CYCLONICALLY INTO LAKE MICHIGAN AND SW PORTIONS OF
THE STATE. A WEAKER EXTENSION OF THAT ENERGY IS SEEN ON THE IR
SATELLITE AS FAR SE AS DAY/CMH. THAT FORCING WILL MAKE ITS WAY INTO
OUR CWA THIS AFTERNOON. THERE ARE SOME BREAKS IN THE CLOUDS ACROSS
FAR SRN MI PRESENTLY AND THIS WILL HELP DESTABILIZE THE BOUNDARY
LAYER AS WE WAIT FOR MORE FORCING IN THE WAY OF COLD FRONT/TRIPLE
POINT SFC FEATURES TO ADVANCE. WARM FRONT IS NOW DRAPED ACROSS THE
THUMB AREA AS SEEN IN SFC OBS. ALSO OBSERVED ON DTX RADAR ARE
SEVERAL GRAVITY WAVES (SEEN AS FINE LINES A BIT THICKER THAN OUTFLOW
BOUNDARIES) LIKELY PERTURBATING FROM THE PARENT UPPER LOW AND JET
STREAM DYNAMICS.
WITH THE ABOVE-MENTIONED FORCING MECHANISMS WE ARE STILL ONLY
DEALING WITH THE PREVIOUSLY ADVERTISED 500 J/KG OF CAPE. ADDL SFC
HEATING WILL SQUEEZE 1 TO 1.5 J/G OUT OF A MODIFIED SOUNDING...BUT
TO THIS POINT THE CELLS THAT POPPED UP IN THIS AIRMASS HAVE NOT HAD
STRONG UPDRAFTS. WE DO HAVE A GOOD AMOUNT OF SHEER AS OBSERVED IN AN
18Z DTX SOUNDING...MOSTLY AS SPEED INCREASE WITH HEIGHT, BUT ONLY
SLIGHT VEERING.
ALSO AMONG MARGINAL INGREDIENTS IS MOISTURE CONTENT THAT HOVERS
AROUND MID 60S DEWPOINT TEMPERATURES AND 1.5 INCHES PW. SLIGHT RISK
FOR SEVERE IS STILL WARRANTED AS THE EVOLUTION OF OUR ENVIRONMENT
WILL CHANGE THESE INGREDIENTS WITH TIME. POP-UP CELLS ACROSS SRN MI
AND NRN IN WILL TELL THE STORY FOR FUTURE DEVELOPMENT. WITH THE HIGH
SHEER SETUP, WOULD NOT BE SURPRISED TO SEE WEAK TORNADIC ACTIVITY,
AND ALSO WIND DAMAGE IN ANY LONGER LIVED SINGLE CELLS OR BOWED LINE
SEGMENT STORMS. LIMITED UPDRAFT STRENGTH WILL PROBABLY KEEP HAIL
SIZE ON A SMALLER SCALE.
SEVERE POTENTIAL DROPS OFF AFTER 00Z AS SRN 7 COUNTIES WILL RECOVER
WITH A DRY PERIOD UNDER OVERCAST SKIES. SAGINAW VALLEY REMAINS IN THE
FRONTAL ZONE AS THE UPPER LOW PIVOTS EASTWARD OVERNIGHT AND WILL
HOLD A CATEGORICAL POP THERE...FADED TO LIKELY SOUTH OF THERE.
LONG TERM...THURSDAY THROUGH TUESDAY
THE HIGH AMPLITUDE AND RELATIVELY STATIC LONGWAVE PATTERN OF RECENT
DAYS MARKED BY A CLOSED MID LEVEL CIRCULATION MEANDERING OVER THE
UPPER MS VALLEY WILL FINALLY SEE SOME FORWARD PROGRESS THROUGH THE
END OF THE WEEK. THE EXPECTED EASTWARD PROPAGATION OF THE ENTIRE
LONGWAVE TROUGH STRUCTURE THROUGH SOUTHEAST MICHIGAN ON THURSDAY
WILL UNFOLD AS EXTENSIVE UPPER RIDGING TAKES RESIDENCE THROUGH THE
PLAINS. THE ATTENDANT SURFACE COLD FRONTAL BOUNDARY WILL BE
MIGRATING SOUTHEASTWARD AND THROUGH LOWER MICHIGAN BY EARLY
THURSDAY. GREATEST FORCING WILL ALIGN ALONG THE 850-925 MB FRONTAL
SLOPE...WITH A PERIOD OF HEIGHTENED MID LEVEL FGEN FORCING AND
DEFORMATION EMERGING LOCALLY AS A TRAILING SHARP MID LEVEL SHEAR
AXIS NOW SEEN ON WATER VAPOR STREAMING THROUGH WESTERN ONTARIO
SWEEPS OVER THE FRONTAL ZONE. LOW LEVEL LAPSE RATES STEEPEN
MODESTLY BELOW THIS LAYER IN RESPONSE TO DEVELOPING WEAK COLD AIR
ADVECTION. GIVEN A SUFFICIENTLY DEEP MOISTURE PROFILE...THIS
ENVIRONMENT WILL SUPPORT THE MAINTENANCE/EXPANSION IN
SHOWER ACTIVITY AS THE FRONT WORKS THROUGH ON THURSDAY. THE
COMBINATION OF THE ADVECTIVE PROCESS AND THE LIMITED HEATING
POTENTIAL UNDER SUBSTANTIAL CLOUD COVER WILL CERTAINLY RESTRICT
THE TEMPERATURE RESPONSE...HIGH TEMPERATURES LIKELY CONFINED TO
WITHIN SEVERAL DEGREE OF MORNING LOWS. THIS TRANSLATES INTO A
SHARPER NORTH TO SOUTH TEMPERATURES GRADIENT...READINGS RANGING
FROM AROUND 50 IN THE THUMB TO MID 60S NEAR THE OHIO BORDER.
STEADY COLD/DRY AIR ADVECTION WILL PROVIDE A DEFINITIVE BACK EDGE TO
THIS MOISTURE AXIS WITH A PROGRESSIVE CLEARING TREND COMMENCING FROM
MID AFTERNOON INTO THE EVENING HOURS FROM NORTHWEST TO SOUTHEAST.
CRISP CP AIRMASS WILL FIRMLY SETTLE IN OVERNIGHT WITHIN DEEPENING
NORTHERLY FLOW ALONG THE EASTERN EDGE OF EXPANDING HIGH PRESSURE
OVER THE UPPER MIDWEST. 850 MB TEMPERATURES STILL LOOK TO BOTTOM
OUT AROUND THE FREEZING MARK BY 12Z FRIDAY MORNING. BOUNDARY
LAYER WILL LIKELY REMAIN MIXED ENOUGH TO PREVENT A MORE PRONOUNCED
RADIATIONAL COOLING ENVIRONMENT...BUT THE GENERAL STRENGTH OF THIS
AIRMASS WILL SUPPORT LOWS OF UPPER 30S FOR ALL LOCALES OUTSIDE OF
THE DETROIT HEAT ISLAND INFLUENCE. POCKETS OF PATCHY FROST NOT OUT
OF THE QUESTION...ALTHOUGH A DRYING LOW LEVEL COLUMN AND THE
QUESTION OF LINGERING MIXING REMAIN MITIGATING FACTORS TO POTENTIAL
FORMATION.
EXTENDED STRETCH OF RELATIVELY BENIGN WEATHER CONDITIONS WILL EXIST
FROM FRIDAY RIGHT THROUGH NEXT WEEKEND AS THE REGION SETTLES INTO
DRY CONFLUENT NORTHWEST FLOW ANCHORED OVER GENERAL SURFACE RIDGING.
SHORTWAVE ENERGY AND ANY ASSOCIATED WARM/MOIST AIR ADVECTION
COMPONENT ROUNDING THE APEX OF THE PREVAILING UPPER RIDGE DRAPED
OVER THE PLAINS WILL TEND TO ARC DOWN THE PRIMARY INSTABILITY
GRADIENT CONFINED WELL TO THE SOUTHWEST. SIMPLE AIRMASS
MODIFICATION DURING THIS TIME UNDER GENERAL MID LEVEL HEIGHT RISES
AND PLENTY OF INSOLATION IN THE WAKE OF THE DEPARTING LONGWAVE
TROUGH. HIGHS BACK INTO THE MIDDLE 60S FOR INLAND LOCATIONS BY
THE WEEKEND...STILL HOLDING A CATEGORY COOLER ALONG THE THUMB AND
OTHER IMMEDIATE NEARSHORE LOCALES.
MARINE...
AN UNSTABLE ENVIRONMENT THIS EVENING WILL BRING A CHANCE OF STRONG
TO SEVERE THUNDERSTORMS THROUGH 8PM. AFTER THAT TIME LINGERING
THUNDERSHOWERS ARE POSSIBLE. FOG WILL AGAIN BE POSSIBLE OUT AHEAD OF
THE FRONTAL ZONE...MAINLY SOUTHERN HALF OF LAKE HURON OVERNIGHT.
WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS BY THURSDAY
MORNING...AS THE MAIN SURFACE LOW AND TRAILING COLD FRONT PUSH OFF
TO THE EAST. WINDS AND WAVES WILL INCREASE GREATLY WITH THE
ADVECTION OF COLD AND DRY AIR...AND THIS LEAD TO ISSUANCE OF A SMALL
CRAFT ADVISORY FOR MUCH OF NEARSHORE LAKE HURON. HIGH PRESSURE WILL
BUILD IN ACROSS THE GREAT LAKES ON FRIDAY...BRINGING QUIET WEATHER
AND COOLER TEMPERATURES TO THE REGION.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON INCLUDING OUTER SAGINAW BAY...FROM 10 AM THURSDAY TO 10
PM THURSDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......JVC
AVIATION.....JVC
SHORT TERM...MM
LONG TERM....MR
MARINE.......MM
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 222314 CCA
AFDDTX
AREA FORECAST DISCUSSION...ADDED DTW THRESHOLD THREAT
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
707 PM EDT WED MAY 22 2013
.AVIATION...
//DISCUSSION...
ACTIVE AREAS OF SHOWERS AND A FEW TSTORMS ON KDTX RADAR WILL
CONTINUE TO DECREASE IN INTENSITY AND COVERAGE OVER THE NEXT FEW
HOURS AS DIURNAL INSTABILITY IS LOST. THE POTENTIAL EXCEPTION WILL
BE THE CLUSTER OF THUNDERSTORMS SEEN LEAVING NE INDIANA AND ENTERING
SE MICHIGAN AT APPROX 2300Z THIS EVENING. THE ORGANIZED NATURE OF
THESE STORMS SUGGESTS THAT THEY WILL AT LEAST HAVE THE POTENTIAL TO
HOLD TOGETHER LONG ENOUGH TO AFFECT THE DETROIT AREA AIRFIELDS OF
KDTW/KYIP DURING THE FIRST HOUR OR SO OF THE TAF PERIOD. A
PREVAILING FORECAST GROUP WILL BE INCLUDED TO CONVEY BEST IDEA OF
TIMING WITH FURTHER AMDS ISSUED IF NECESSARY TO ACCOUNT FOR LATEST
TRENDS.
BY THURSDAY MORNING, THE COMBINATION OF LOW-LEVEL COLD ADVECTION AND
WEAKENING MOISTURE TRANSPORT INTO A SLOW-MOVING FRONTAL ZONE WILL
RESULT IN LIGHT RAINFALL AND A DETERIORATION TO MVFR CONDITIONS THAT
WILL PERSIST WELL INTO THURSDAY AFTERNOON. RAPID CLEARING IS
EXPECTED NEAR OR SLIGHTLY AFTER 00Z FRI AS HIGH PRESSURE AND DRY
NORTHERLY FLOW SETTLE INTO THE REGION.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE THAT A THUNDERSTORM WILL IMPACT KDTW AIRSPACE PRIOR
TO 02Z.
* HIGH CONFIDENCE IN CEILINGS BELOW 5000 FEET BY 12Z
&&
.PREV DISCUSSION...ISSUED 325 PM EDT WED MAY 22 2013
SHORT TERM...THIS EVENING AND TONIGHT
BROAD UPPER LOW OVER MN/IA THIS AFTERNOON CONTINUES TO PIVOT
SHORTWAVE ENERGY CYCLONICALLY INTO LAKE MICHIGAN AND SW PORTIONS OF
THE STATE. A WEAKER EXTENSION OF THAT ENERGY IS SEEN ON THE IR
SATELLITE AS FAR SE AS DAY/CMH. THAT FORCING WILL MAKE ITS WAY INTO
OUR CWA THIS AFTERNOON. THERE ARE SOME BREAKS IN THE CLOUDS ACROSS
FAR SRN MI PRESENTLY AND THIS WILL HELP DESTABILIZE THE BOUNDARY
LAYER AS WE WAIT FOR MORE FORCING IN THE WAY OF COLD FRONT/TRIPLE
POINT SFC FEATURES TO ADVANCE. WARM FRONT IS NOW DRAPED ACROSS THE
THUMB AREA AS SEEN IN SFC OBS. ALSO OBSERVED ON DTX RADAR ARE
SEVERAL GRAVITY WAVES (SEEN AS FINE LINES A BIT THICKER THAN OUTFLOW
BOUNDARIES) LIKELY PERTURBATING FROM THE PARENT UPPER LOW AND JET
STREAM DYNAMICS.
WITH THE ABOVE-MENTIONED FORCING MECHANISMS WE ARE STILL ONLY
DEALING WITH THE PREVIOUSLY ADVERTISED 500 J/KG OF CAPE. ADDL SFC
HEATING WILL SQUEEZE 1 TO 1.5 J/G OUT OF A MODIFIED SOUNDING...BUT
TO THIS POINT THE CELLS THAT POPPED UP IN THIS AIRMASS HAVE NOT HAD
STRONG UPDRAFTS. WE DO HAVE A GOOD AMOUNT OF SHEER AS OBSERVED IN AN
18Z DTX SOUNDING...MOSTLY AS SPEED INCREASE WITH HEIGHT, BUT ONLY
SLIGHT VEERING.
ALSO AMONG MARGINAL INGREDIENTS IS MOISTURE CONTENT THAT HOVERS
AROUND MID 60S DEWPOINT TEMPERATURES AND 1.5 INCHES PW. SLIGHT RISK
FOR SEVERE IS STILL WARRANTED AS THE EVOLUTION OF OUR ENVIRONMENT
WILL CHANGE THESE INGREDIENTS WITH TIME. POP-UP CELLS ACROSS SRN MI
AND NRN IN WILL TELL THE STORY FOR FUTURE DEVELOPMENT. WITH THE HIGH
SHEER SETUP, WOULD NOT BE SURPRISED TO SEE WEAK TORNADIC ACTIVITY,
AND ALSO WIND DAMAGE IN ANY LONGER LIVED SINGLE CELLS OR BOWED LINE
SEGMENT STORMS. LIMITED UPDRAFT STRENGTH WILL PROBABLY KEEP HAIL
SIZE ON A SMALLER SCALE.
SEVERE POTENTIAL DROPS OFF AFTER 00Z AS SRN 7 COUNTIES WILL RECOVER
WITH A DRY PERIOD UNDER OVERCAST SKIES. SAGINAW VALLEY REMAINS IN THE
FRONTAL ZONE AS THE UPPER LOW PIVOTS EASTWARD OVERNIGHT AND WILL
HOLD A CATEGORICAL POP THERE...FADED TO LIKELY SOUTH OF THERE.
LONG TERM...THURSDAY THROUGH TUESDAY
THE HIGH AMPLITUDE AND RELATIVELY STATIC LONGWAVE PATTERN OF RECENT
DAYS MARKED BY A CLOSED MID LEVEL CIRCULATION MEANDERING OVER THE
UPPER MS VALLEY WILL FINALLY SEE SOME FORWARD PROGRESS THROUGH THE
END OF THE WEEK. THE EXPECTED EASTWARD PROPAGATION OF THE ENTIRE
LONGWAVE TROUGH STRUCTURE THROUGH SOUTHEAST MICHIGAN ON THURSDAY
WILL UNFOLD AS EXTENSIVE UPPER RIDGING TAKES RESIDENCE THROUGH THE
PLAINS. THE ATTENDANT SURFACE COLD FRONTAL BOUNDARY WILL BE
MIGRATING SOUTHEASTWARD AND THROUGH LOWER MICHIGAN BY EARLY
THURSDAY. GREATEST FORCING WILL ALIGN ALONG THE 850-925 MB FRONTAL
SLOPE...WITH A PERIOD OF HEIGHTENED MID LEVEL FGEN FORCING AND
DEFORMATION EMERGING LOCALLY AS A TRAILING SHARP MID LEVEL SHEAR
AXIS NOW SEEN ON WATER VAPOR STREAMING THROUGH WESTERN ONTARIO
SWEEPS OVER THE FRONTAL ZONE. LOW LEVEL LAPSE RATES STEEPEN
MODESTLY BELOW THIS LAYER IN RESPONSE TO DEVELOPING WEAK COLD AIR
ADVECTION. GIVEN A SUFFICIENTLY DEEP MOISTURE PROFILE...THIS
ENVIRONMENT WILL SUPPORT THE MAINTENANCE/EXPANSION IN
SHOWER ACTIVITY AS THE FRONT WORKS THROUGH ON THURSDAY. THE
COMBINATION OF THE ADVECTIVE PROCESS AND THE LIMITED HEATING
POTENTIAL UNDER SUBSTANTIAL CLOUD COVER WILL CERTAINLY RESTRICT
THE TEMPERATURE RESPONSE...HIGH TEMPERATURES LIKELY CONFINED TO
WITHIN SEVERAL DEGREE OF MORNING LOWS. THIS TRANSLATES INTO A
SHARPER NORTH TO SOUTH TEMPERATURES GRADIENT...READINGS RANGING
FROM AROUND 50 IN THE THUMB TO MID 60S NEAR THE OHIO BORDER.
STEADY COLD/DRY AIR ADVECTION WILL PROVIDE A DEFINITIVE BACK EDGE TO
THIS MOISTURE AXIS WITH A PROGRESSIVE CLEARING TREND COMMENCING FROM
MID AFTERNOON INTO THE EVENING HOURS FROM NORTHWEST TO SOUTHEAST.
CRISP CP AIRMASS WILL FIRMLY SETTLE IN OVERNIGHT WITHIN DEEPENING
NORTHERLY FLOW ALONG THE EASTERN EDGE OF EXPANDING HIGH PRESSURE
OVER THE UPPER MIDWEST. 850 MB TEMPERATURES STILL LOOK TO BOTTOM
OUT AROUND THE FREEZING MARK BY 12Z FRIDAY MORNING. BOUNDARY
LAYER WILL LIKELY REMAIN MIXED ENOUGH TO PREVENT A MORE PRONOUNCED
RADIATIONAL COOLING ENVIRONMENT...BUT THE GENERAL STRENGTH OF THIS
AIRMASS WILL SUPPORT LOWS OF UPPER 30S FOR ALL LOCALES OUTSIDE OF
THE DETROIT HEAT ISLAND INFLUENCE. POCKETS OF PATCHY FROST NOT OUT
OF THE QUESTION...ALTHOUGH A DRYING LOW LEVEL COLUMN AND THE
QUESTION OF LINGERING MIXING REMAIN MITIGATING FACTORS TO POTENTIAL
FORMATION.
EXTENDED STRETCH OF RELATIVELY BENIGN WEATHER CONDITIONS WILL EXIST
FROM FRIDAY RIGHT THROUGH NEXT WEEKEND AS THE REGION SETTLES INTO
DRY CONFLUENT NORTHWEST FLOW ANCHORED OVER GENERAL SURFACE RIDGING.
SHORTWAVE ENERGY AND ANY ASSOCIATED WARM/MOIST AIR ADVECTION
COMPONENT ROUNDING THE APEX OF THE PREVAILING UPPER RIDGE DRAPED
OVER THE PLAINS WILL TEND TO ARC DOWN THE PRIMARY INSTABILITY
GRADIENT CONFINED WELL TO THE SOUTHWEST. SIMPLE AIRMASS
MODIFICATION DURING THIS TIME UNDER GENERAL MID LEVEL HEIGHT RISES
AND PLENTY OF INSOLATION IN THE WAKE OF THE DEPARTING LONGWAVE
TROUGH. HIGHS BACK INTO THE MIDDLE 60S FOR INLAND LOCATIONS BY
THE WEEKEND...STILL HOLDING A CATEGORY COOLER ALONG THE THUMB AND
OTHER IMMEDIATE NEARSHORE LOCALES.
MARINE...
AN UNSTABLE ENVIRONMENT THIS EVENING WILL BRING A CHANCE OF STRONG
TO SEVERE THUNDERSTORMS THROUGH 8PM. AFTER THAT TIME LINGERING
THUNDERSHOWERS ARE POSSIBLE. FOG WILL AGAIN BE POSSIBLE OUT AHEAD OF
THE FRONTAL ZONE...MAINLY SOUTHERN HALF OF LAKE HURON OVERNIGHT.
WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS BY THURSDAY
MORNING...AS THE MAIN SURFACE LOW AND TRAILING COLD FRONT PUSH OFF
TO THE EAST. WINDS AND WAVES WILL INCREASE GREATLY WITH THE
ADVECTION OF COLD AND DRY AIR...AND THIS LEAD TO ISSUANCE OF A SMALL
CRAFT ADVISORY FOR MUCH OF NEARSHORE LAKE HURON. HIGH PRESSURE WILL
BUILD IN ACROSS THE GREAT LAKES ON FRIDAY...BRINGING QUIET WEATHER
AND COOLER TEMPERATURES TO THE REGION.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON INCLUDING OUTER SAGINAW BAY...FROM 10 AM THURSDAY TO 10
PM THURSDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....JVC
SHORT TERM...MM
LONG TERM....MR
MARINE.......MM
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 222307
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
707 PM EDT WED MAY 22 2013
.AVIATION...
//DISCUSSION...
ACTIVE AREAS OF SHOWERS AND A FEW TSTORMS ON KDTX RADAR WILL
CONTINUE TO DECREASE IN INTENSITY AND COVERAGE OVER THE NEXT FEW
HOURS AS DIURNAL INSTABILITY IS LOST. THE POTENTIAL EXCEPTION WILL
BE THE CLUSTER OF THUNDERSTORMS SEEN LEAVING NE INDIANA AND ENTERING
SE MICHIGAN AT APPROX 2300Z THIS EVENING. THE ORGANIZED NATURE OF
THESE STORMS SUGGESTS THAT THEY WILL AT LEAST HAVE THE POTENTIAL TO
HOLD TOGETHER LONG ENOUGH TO AFFECT THE DETROIT AREA AIRFIELDS OF
KDTW/KYIP DURING THE FIRST HOUR OR SO OF THE TAF PERIOD. A
PREVAILING FORECAST GROUP WILL BE INCLUDED TO CONVEY BEST IDEA OF
TIMING WITH FURTHER AMDS ISSUED IF NECESSARY TO ACCOUNT FOR LATEST
TRENDS.
BY THURSDAY MORNING, THE COMBINATION OF LOW-LEVEL COLD ADVECTION AND
WEAKENING MOISTURE TRANSPORT INTO A SLOW-MOVING FRONTAL ZONE WILL
RESULT IN LIGHT RAINFALL AND A DETERIORATION TO MVFR CONDITIONS THAT
WILL PERSIST WELL INTO THURSDAY AFTERNOON. RAPID CLEARING IS
EXPECTED NEAR OR SLIGHTLY AFTER 00Z FRI AS HIGH PRESSURE AND DRY
NORTHERLY FLOW SETTLE INTO THE REGION.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE THAT A THUNDERSTORM WILL IMPACT KDTW AIRSPACE PRIOR
TO 02Z.
&&
.PREV DISCUSSION...ISSUED 325 PM EDT WED MAY 22 2013
SHORT TERM...THIS EVENING AND TONIGHT
BROAD UPPER LOW OVER MN/IA THIS AFTERNOON CONTINUES TO PIVOT
SHORTWAVE ENERGY CYCLONICALLY INTO LAKE MICHIGAN AND SW PORTIONS OF
THE STATE. A WEAKER EXTENSION OF THAT ENERGY IS SEEN ON THE IR
SATELLITE AS FAR SE AS DAY/CMH. THAT FORCING WILL MAKE ITS WAY INTO
OUR CWA THIS AFTERNOON. THERE ARE SOME BREAKS IN THE CLOUDS ACROSS
FAR SRN MI PRESENTLY AND THIS WILL HELP DESTABILIZE THE BOUNDARY
LAYER AS WE WAIT FOR MORE FORCING IN THE WAY OF COLD FRONT/TRIPLE
POINT SFC FEATURES TO ADVANCE. WARM FRONT IS NOW DRAPED ACROSS THE
THUMB AREA AS SEEN IN SFC OBS. ALSO OBSERVED ON DTX RADAR ARE
SEVERAL GRAVITY WAVES (SEEN AS FINE LINES A BIT THICKER THAN OUTFLOW
BOUNDARIES) LIKELY PERTURBATING FROM THE PARENT UPPER LOW AND JET
STREAM DYNAMICS.
WITH THE ABOVE-MENTIONED FORCING MECHANISMS WE ARE STILL ONLY
DEALING WITH THE PREVIOUSLY ADVERTISED 500 J/KG OF CAPE. ADDL SFC
HEATING WILL SQUEEZE 1 TO 1.5 J/G OUT OF A MODIFIED SOUNDING...BUT
TO THIS POINT THE CELLS THAT POPPED UP IN THIS AIRMASS HAVE NOT HAD
STRONG UPDRAFTS. WE DO HAVE A GOOD AMOUNT OF SHEER AS OBSERVED IN AN
18Z DTX SOUNDING...MOSTLY AS SPEED INCREASE WITH HEIGHT, BUT ONLY
SLIGHT VEERING.
ALSO AMONG MARGINAL INGREDIENTS IS MOISTURE CONTENT THAT HOVERS
AROUND MID 60S DEWPOINT TEMPERATURES AND 1.5 INCHES PW. SLIGHT RISK
FOR SEVERE IS STILL WARRANTED AS THE EVOLUTION OF OUR ENVIRONMENT
WILL CHANGE THESE INGREDIENTS WITH TIME. POP-UP CELLS ACROSS SRN MI
AND NRN IN WILL TELL THE STORY FOR FUTURE DEVELOPMENT. WITH THE HIGH
SHEER SETUP, WOULD NOT BE SURPRISED TO SEE WEAK TORNADIC ACTIVITY,
AND ALSO WIND DAMAGE IN ANY LONGER LIVED SINGLE CELLS OR BOWED LINE
SEGMENT STORMS. LIMITED UPDRAFT STRENGTH WILL PROBABLY KEEP HAIL
SIZE ON A SMALLER SCALE.
SEVERE POTENTIAL DROPS OFF AFTER 00Z AS SRN 7 COUNTIES WILL RECOVER
WITH A DRY PERIOD UNDER OVERCAST SKIES. SAGINAW VALLEY REMAINS IN THE
FRONTAL ZONE AS THE UPPER LOW PIVOTS EASTWARD OVERNIGHT AND WILL
HOLD A CATEGORICAL POP THERE...FADED TO LIKELY SOUTH OF THERE.
LONG TERM...THURSDAY THROUGH TUESDAY
THE HIGH AMPLITUDE AND RELATIVELY STATIC LONGWAVE PATTERN OF RECENT
DAYS MARKED BY A CLOSED MID LEVEL CIRCULATION MEANDERING OVER THE
UPPER MS VALLEY WILL FINALLY SEE SOME FORWARD PROGRESS THROUGH THE
END OF THE WEEK. THE EXPECTED EASTWARD PROPAGATION OF THE ENTIRE
LONGWAVE TROUGH STRUCTURE THROUGH SOUTHEAST MICHIGAN ON THURSDAY
WILL UNFOLD AS EXTENSIVE UPPER RIDGING TAKES RESIDENCE THROUGH THE
PLAINS. THE ATTENDANT SURFACE COLD FRONTAL BOUNDARY WILL BE
MIGRATING SOUTHEASTWARD AND THROUGH LOWER MICHIGAN BY EARLY
THURSDAY. GREATEST FORCING WILL ALIGN ALONG THE 850-925 MB FRONTAL
SLOPE...WITH A PERIOD OF HEIGHTENED MID LEVEL FGEN FORCING AND
DEFORMATION EMERGING LOCALLY AS A TRAILING SHARP MID LEVEL SHEAR
AXIS NOW SEEN ON WATER VAPOR STREAMING THROUGH WESTERN ONTARIO
SWEEPS OVER THE FRONTAL ZONE. LOW LEVEL LAPSE RATES STEEPEN
MODESTLY BELOW THIS LAYER IN RESPONSE TO DEVELOPING WEAK COLD AIR
ADVECTION. GIVEN A SUFFICIENTLY DEEP MOISTURE PROFILE...THIS
ENVIRONMENT WILL SUPPORT THE MAINTENANCE/EXPANSION IN
SHOWER ACTIVITY AS THE FRONT WORKS THROUGH ON THURSDAY. THE
COMBINATION OF THE ADVECTIVE PROCESS AND THE LIMITED HEATING
POTENTIAL UNDER SUBSTANTIAL CLOUD COVER WILL CERTAINLY RESTRICT
THE TEMPERATURE RESPONSE...HIGH TEMPERATURES LIKELY CONFINED TO
WITHIN SEVERAL DEGREE OF MORNING LOWS. THIS TRANSLATES INTO A
SHARPER NORTH TO SOUTH TEMPERATURES GRADIENT...READINGS RANGING
FROM AROUND 50 IN THE THUMB TO MID 60S NEAR THE OHIO BORDER.
STEADY COLD/DRY AIR ADVECTION WILL PROVIDE A DEFINITIVE BACK EDGE TO
THIS MOISTURE AXIS WITH A PROGRESSIVE CLEARING TREND COMMENCING FROM
MID AFTERNOON INTO THE EVENING HOURS FROM NORTHWEST TO SOUTHEAST.
CRISP CP AIRMASS WILL FIRMLY SETTLE IN OVERNIGHT WITHIN DEEPENING
NORTHERLY FLOW ALONG THE EASTERN EDGE OF EXPANDING HIGH PRESSURE
OVER THE UPPER MIDWEST. 850 MB TEMPERATURES STILL LOOK TO BOTTOM
OUT AROUND THE FREEZING MARK BY 12Z FRIDAY MORNING. BOUNDARY
LAYER WILL LIKELY REMAIN MIXED ENOUGH TO PREVENT A MORE PRONOUNCED
RADIATIONAL COOLING ENVIRONMENT...BUT THE GENERAL STRENGTH OF THIS
AIRMASS WILL SUPPORT LOWS OF UPPER 30S FOR ALL LOCALES OUTSIDE OF
THE DETROIT HEAT ISLAND INFLUENCE. POCKETS OF PATCHY FROST NOT OUT
OF THE QUESTION...ALTHOUGH A DRYING LOW LEVEL COLUMN AND THE
QUESTION OF LINGERING MIXING REMAIN MITIGATING FACTORS TO POTENTIAL
FORMATION.
EXTENDED STRETCH OF RELATIVELY BENIGN WEATHER CONDITIONS WILL EXIST
FROM FRIDAY RIGHT THROUGH NEXT WEEKEND AS THE REGION SETTLES INTO
DRY CONFLUENT NORTHWEST FLOW ANCHORED OVER GENERAL SURFACE RIDGING.
SHORTWAVE ENERGY AND ANY ASSOCIATED WARM/MOIST AIR ADVECTION
COMPONENT ROUNDING THE APEX OF THE PREVAILING UPPER RIDGE DRAPED
OVER THE PLAINS WILL TEND TO ARC DOWN THE PRIMARY INSTABILITY
GRADIENT CONFINED WELL TO THE SOUTHWEST. SIMPLE AIRMASS
MODIFICATION DURING THIS TIME UNDER GENERAL MID LEVEL HEIGHT RISES
AND PLENTY OF INSOLATION IN THE WAKE OF THE DEPARTING LONGWAVE
TROUGH. HIGHS BACK INTO THE MIDDLE 60S FOR INLAND LOCATIONS BY
THE WEEKEND...STILL HOLDING A CATEGORY COOLER ALONG THE THUMB AND
OTHER IMMEDIATE NEARSHORE LOCALES.
MARINE...
AN UNSTABLE ENVIRONMENT THIS EVENING WILL BRING A CHANCE OF STRONG
TO SEVERE THUNDERSTORMS THROUGH 8PM. AFTER THAT TIME LINGERING
THUNDERSHOWERS ARE POSSIBLE. FOG WILL AGAIN BE POSSIBLE OUT AHEAD OF
THE FRONTAL ZONE...MAINLY SOUTHERN HALF OF LAKE HURON OVERNIGHT.
WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS BY THURSDAY
MORNING...AS THE MAIN SURFACE LOW AND TRAILING COLD FRONT PUSH OFF
TO THE EAST. WINDS AND WAVES WILL INCREASE GREATLY WITH THE
ADVECTION OF COLD AND DRY AIR...AND THIS LEAD TO ISSUANCE OF A SMALL
CRAFT ADVISORY FOR MUCH OF NEARSHORE LAKE HURON. HIGH PRESSURE WILL
BUILD IN ACROSS THE GREAT LAKES ON FRIDAY...BRINGING QUIET WEATHER
AND COOLER TEMPERATURES TO THE REGION.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON INCLUDING OUTER SAGINAW BAY...FROM 10 AM THURSDAY TO 10
PM THURSDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....JVC
SHORT TERM...MM
LONG TERM....MR
MARINE.......MM
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 221925
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
325 PM EDT WED MAY 22 2013
.SHORT TERM...THIS EVENING AND TONIGHT
BROAD UPPER LOW OVER MN/IA THIS AFTERNOON CONTINUES TO PIVOT
SHORTWAVE ENERGY CYCLONICALLY INTO LAKE MICHIGAN AND SW PORTIONS OF
THE STATE. A WEAKER EXTENSION OF THAT ENERGY IS SEEN ON THE IR
SATELLITE AS FAR SE AS DAY/CMH. THAT FORCING WILL MAKE ITS WAY INTO
OUR CWA THIS AFTERNOON. THERE ARE SOME BREAKS IN THE CLOUDS ACROSS
FAR SRN MI PRESENTLY AND THIS WILL HELP DESTABILIZE THE BOUNDARY
LAYER AS WE WAIT FOR MORE FORCING IN THE WAY OF COLD FRONT/TRIPLE
POINT SFC FEATURES TO ADVANCE. WARM FRONT IS NOW DRAPED ACROSS THE
THUMB AREA AS SEEN IN SFC OBS. ALSO OBSERVED ON DTX RADAR ARE
SEVERAL GRAVITY WAVES (SEEN AS FINE LINES A BIT THICKER THAN OUTFLOW
BOUNDARIES) LIKELY PERTURBATING FROM THE PARENT UPPER LOW AND JET
STREAM DYNAMICS.
WITH THE ABOVE-MENTIONED FORCING MECHANISMS WE ARE STILL ONLY
DEALING WITH THE PREVIOUSLY ADVERTISED 500 J/KG OF CAPE. ADDL SFC
HEATING WILL SQUEEZE 1 TO 1.5 J/G OUT OF A MODIFIED SOUNDING...BUT
TO THIS POINT THE CELLS THAT POPPED UP IN THIS AIRMASS HAVE NOT HAD
STRONG UPDRAFTS. WE DO HAVE A GOOD AMOUNT OF SHEER AS OBSERVED IN AN
18Z DTX SOUNDING...MOSTLY AS SPEED INCREASE WITH HEIGHT, BUT ONLY
SLIGHT VEERING.
ALSO AMONG MARGINAL INGREDIENTS IS MOISTURE CONTENT THAT HOVERS
AROUND MID 60S DEWPOINT TEMPERATURES AND 1.5 INCHES PW. SLIGHT RISK
FOR SEVERE IS STILL WARRANTED AS THE EVOLUTION OF OUR ENVIRONMENT
WILL CHANGE THESE INGREDIENTS WITH TIME. POP-UP CELLS ACROSS SRN MI
AND NRN IN WILL TELL THE STORY FOR FUTURE DEVELOPMENT. WITH THE HIGH
SHEER SETUP, WOULD NOT BE SURPRISED TO SEE WEAK TORNADIC ACTIVITY,
AND ALSO WIND DAMAGE IN ANY LONGER LIVED SINGLE CELLS OR BOWED LINE
SEGMENT STORMS. LIMITED UPDRAFT STRENGTH WILL PROBABLY KEEP HAIL
SIZE ON A SMALLER SCALE.
SEVERE POTENTIAL DROPS OFF AFTER 00Z AS SRN 7 COUNTIES WILL RECOVER
WITH A DRY PERIOD UNDER OVERCAST SKIES. SAGINAW VALLEY REMAINS IN THE
FRONTAL ZONE AS THE UPPER LOW PIVOTS EASTWARD OVERNIGHT AND WILL
HOLD A CATEGORICAL POP THERE...FADED TO LIKELY SOUTH OF THERE.
&&
.LONG TERM...THURSDAY THROUGH TUESDAY
THE HIGH AMPLITUDE AND RELATIVELY STATIC LONGWAVE PATTERN OF RECENT
DAYS MARKED BY A CLOSED MID LEVEL CIRCULATION MEANDERING OVER THE
UPPER MS VALLEY WILL FINALLY SEE SOME FORWARD PROGRESS THROUGH THE
END OF THE WEEK. THE EXPECTED EASTWARD PROPAGATION OF THE ENTIRE
LONGWAVE TROUGH STRUCTURE THROUGH SOUTHEAST MICHIGAN ON THURSDAY
WILL UNFOLD AS EXTENSIVE UPPER RIDGING TAKES RESIDENCE THROUGH THE
PLAINS. THE ATTENDANT SURFACE COLD FRONTAL BOUNDARY WILL BE
MIGRATING SOUTHEASTWARD AND THROUGH LOWER MICHIGAN BY EARLY
THURSDAY. GREATEST FORCING WILL ALIGN ALONG THE 850-925 MB FRONTAL
SLOPE...WITH A PERIOD OF HEIGHTENED MID LEVEL FGEN FORCING AND
DEFORMATION EMERGING LOCALLY AS A TRAILING SHARP MID LEVEL SHEAR
AXIS NOW SEEN ON WATER VAPOR STREAMING THROUGH WESTERN ONTARIO
SWEEPS OVER THE FRONTAL ZONE. LOW LEVEL LAPSE RATES STEEPEN
MODESTLY BELOW THIS LAYER IN RESPONSE TO DEVELOPING WEAK COLD AIR
ADVECTION. GIVEN A SUFFICIENTLY DEEP MOISTURE PROFILE...THIS
ENVIRONMENT WILL SUPPORT THE MAINTENANCE/EXPANSION IN
SHOWER ACTIVITY AS THE FRONT WORKS THROUGH ON THURSDAY. THE
COMBINATION OF THE ADVECTIVE PROCESS AND THE LIMITED HEATING
POTENTIAL UNDER SUBSTANTIAL CLOUD COVER WILL CERTAINLY RESTRICT
THE TEMPERATURE RESPONSE...HIGH TEMPERATURES LIKELY CONFINED TO
WITHIN SEVERAL DEGREE OF MORNING LOWS. THIS TRANSLATES INTO A
SHARPER NORTH TO SOUTH TEMPERATURES GRADIENT...READINGS RANGING
FROM AROUND 50 IN THE THUMB TO MID 60S NEAR THE OHIO BORDER.
STEADY COLD/DRY AIR ADVECTION WILL PROVIDE A DEFINITIVE BACK EDGE TO
THIS MOISTURE AXIS WITH A PROGRESSIVE CLEARING TREND COMMENCING FROM
MID AFTERNOON INTO THE EVENING HOURS FROM NORTHWEST TO SOUTHEAST.
CRISP CP AIRMASS WILL FIRMLY SETTLE IN OVERNIGHT WITHIN DEEPENING
NORTHERLY FLOW ALONG THE EASTERN EDGE OF EXPANDING HIGH PRESSURE
OVER THE UPPER MIDWEST. 850 MB TEMPERATURES STILL LOOK TO BOTTOM
OUT AROUND THE FREEZING MARK BY 12Z FRIDAY MORNING. BOUNDARY
LAYER WILL LIKELY REMAIN MIXED ENOUGH TO PREVENT A MORE PRONOUNCED
RADIATIONAL COOLING ENVIRONMENT...BUT THE GENERAL STRENGTH OF THIS
AIRMASS WILL SUPPORT LOWS OF UPPER 30S FOR ALL LOCALES OUTSIDE OF
THE DETROIT HEAT ISLAND INFLUENCE. POCKETS OF PATCHY FROST NOT OUT
OF THE QUESTION...ALTHOUGH A DRYING LOW LEVEL COLUMN AND THE
QUESTION OF LINGERING MIXING REMAIN MITIGATING FACTORS TO POTENTIAL
FORMATION.
EXTENDED STRETCH OF RELATIVELY BENIGN WEATHER CONDITIONS WILL EXIST
FROM FRIDAY RIGHT THROUGH NEXT WEEKEND AS THE REGION SETTLES INTO
DRY CONFLUENT NORTHWEST FLOW ANCHORED OVER GENERAL SURFACE RIDGING.
SHORTWAVE ENERGY AND ANY ASSOCIATED WARM/MOIST AIR ADVECTION
COMPONENT ROUNDING THE APEX OF THE PREVAILING UPPER RIDGE DRAPED
OVER THE PLAINS WILL TEND TO ARC DOWN THE PRIMARY INSTABILITY
GRADIENT CONFINED WELL TO THE SOUTHWEST. SIMPLE AIRMASS
MODIFICATION DURING THIS TIME UNDER GENERAL MID LEVEL HEIGHT RISES
AND PLENTY OF INSOLATION IN THE WAKE OF THE DEPARTING LONGWAVE
TROUGH. HIGHS BACK INTO THE MIDDLE 60S FOR INLAND LOCATIONS BY
THE WEEKEND...STILL HOLDING A CATEGORY COOLER ALONG THE THUMB AND
OTHER IMMEDIATE NEARSHORE LOCALES.
&&
.MARINE...
AN UNSTABLE ENVIRONMENT THIS EVENING WILL BRING A CHANCE OF STRONG
TO SEVERE THUNDERSTORMS THROUGH 8PM. AFTER THAT TIME LINGERING
THUNDERSHOWERS ARE POSSIBLE. FOG WILL AGAIN BE POSSIBLE OUT AHEAD OF
THE FRONTAL ZONE...MAINLY SOUTHERN HALF OF LAKE HURON OVERNIGHT.
WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS BY THURSDAY
MORNING...AS THE MAIN SURFACE LOW AND TRAILING COLD FRONT PUSH OFF
TO THE EAST. WINDS AND WAVES WILL INCREASE GREATLY WITH THE
ADVECTION OF COLD AND DRY AIR...AND THIS LEAD TO ISSUANCE OF A SMALL
CRAFT ADVISORY FOR MUCH OF NEARSHORE LAKE HURON. HIGH PRESSURE WILL
BUILD IN ACROSS THE GREAT LAKES ON FRIDAY...BRINGING QUIET WEATHER
AND COOLER TEMPERATURES TO THE REGION.
&&
.AVIATION...ISSUED 111 PM EDT WED MAY 22 2013
//DISCUSSION...
CENTRAL MI CONTINUES TO SEE LOW CIGS THIS AFTERNOON SO WILL KEEP A
WATCHFUL EYE ON MBS FOR LOWERING. THEY DO HOLD THE BEST CHANCE FOR
DAYTIME SHRA TO DROP VIS...SO DID TEMPO IN MVFR. TRIED TO TIME OUT
THE BEST CHANCE FOR SEVERE WEATHER IN TSTORMS THIS AFTERNOON IN THE
DETROIT SITES WHICH WILL BE 19-23Z TODAY. LOWER CIGS WILL BE LIKELY
OVERNIGHT AND AGAIN PUT MVFR CIGS IN THE FORECAST. GOOD OVERALL
CHANCE FOR -RA WILL BE TOMORROW WITH FROPA FROM NW TO SE ACROSS THE
STATE.
FOR DTW...LIGHT SCATTERED SHOWERS WILL HAVE LITTLE IMPACT UNTIL THE
MORE ORGANIZED STORMS MOVE INTO THE AREA AFTER 19Z. GIVEN CURRENT
RADAR TRENDS...HIGHER CONFIDENCE FOR TSRA IS THE LATTER HALF OF
TEMPO GROUP.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF THUNDERSTORMS 19-23Z.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT
HURON INCLUDING OUTER SAGINAW BAY...FROM 10 AM THURSDAY TO 10
PM THURSDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...MM
LONG TERM....MR
MARINE.......MM
AVIATION.....MM
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 221711
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
111 PM EDT WED MAY 22 2013
.AVIATION...
//DISCUSSION...
CENTRAL MI CONTINUES TO SEE LOW CIGS THIS AFTERNOON SO WILL KEEP A
WATCHFUL EYE ON MBS FOR LOWERING. THEY DO HOLD THE BEST CHANCE FOR
DAYTIME SHRA TO DROP VIS...SO DID TEMPO IN MVFR. TRIED TO TIME OUT
THE BEST CHANCE FOR SEVERE WEATHER IN TSTORMS THIS AFTERNOON IN THE
DETROIT SITES WHICH WILL BE 19-23Z TODAY. LOWER CIGS WILL BE LIKELY
OVERNIGHT AND AGAIN PUT MVFR CIGS IN THE FORECAST. GOOD OVERALL
CHANCE FOR -RA WILL BE TOMORROW WITH FROPA FROM NW TO SE ACROSS THE
STATE.
FOR DTW...LIGHT SCATTERED SHOWERS WILL HAVE LITTLE IMPACT UNTIL THE
MORE ORGANIZED STORMS MOVE INTO THE AREA AFTER 19Z. GIVEN CURRENT
RADAR TRENDS...HIGHER CONFIDENCE FOR TSRA IS THE LATTER HALF OF
TEMPO GROUP.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF THUNDERSTORMS 19-23Z.
&&
.PREV DISCUSSION...ISSUED 1036 AM EDT WED MAY 22 2013
UPDATE...
OVERCAST CONDITIONS ACROSS THE REGION HAVE LIMITED HEATING AND
DESTABILIZATION EARLY TODAY...BUT THERE ARE STILL SEVERAL OTHER
FACTORS TO KEEP SEVERE WEATHER MENTION IN THE FORECAST TODAY.
VISIBLE SATELLITE AND SFC OBS SHOW THE COLD FRONT AS A SHARP
CLEARING LINE AND DROP IN DEWPOINTS ROUGHLY ALONG THE MISSISSIPPI
RIVER FROM WI TO TN. EAST OF THE FRONT FROM ORD TO CVG THERE IS
ANOTHER CLEARING FEATURE THAT IS NEAR THE LOCATION OF A VORTICITY
MAXIMUM/SHORTWAVE ENERGY THAT IS BEING EJECTED NORTHEAST FROM THE
LOWER MS VALLEY. LOCAL HI-RES MODELS AND 12Z NAM SHOWING INITIATION
IN THE SE MI AREA AROUND 18-19Z AHEAD OF THE COLD FRONT/TRIPLE POINT
WITH SEVERE THREATS COMING TO AN END BY 00Z. ONE CAVEAT TO THAT IS
POSSIBLE ADDL CONVECTION IN THE SAGINAW VALLEY WHERE THE TRAILING
SFC LOW WILL BE CO-LOCATED WITH ANOTHER SHORTWAVE AND WOULD HAVE
BETTER UPPER LEVEL DIVERGENCE DUE TO JET ORIENTATION.
SMALL ADJUSTMENTS WERE MADE TO LOWER MAX TEMPS AND ALSO OVERNIGHT
POPS AS THE ENVIRONMENT WILL BE RECOVERING BEFORE NEXT FROPA
EARLY THURS.
PREV DISCUSSION...ISSUED 337 AM EDT WED MAY 22 2013
SHORT TERM...TODAY AND TONIGHT
THE LARGE MID LEVEL CLOSED OFF LOW THAT HAS BEEN PARKED OVER THE
NORTHERN PLAINS WILL MAKE ITS WAY EAST TODAY AND TONIGHT. THE LOW
WILL BEGIN TO MERGE WITH A LARGER AREA OF LOW PRESSURE OVER HUDSON
BAY AND TRANSITION FROM A CLOSED OFF LOW TO A POSITIVELY TILTED
TROUGH AS IT MAKES ITS WAY TOWARD THE WESTERN GREAT LAKES
TODAY...AND EVENTUALLY OVER THE CENTRAL GREAT LAKES TONIGHT. BEFORE
THE LOW TRACKS OVER THE CENTRAL GREAT LAKES...A PIECE OF SHORTWAVE
ENERGY CURRENTLY SPINNING OVER EASTERN OKLAHOMA WILL LIFT NORTHEAST
THROUGH THE CENTRAL GREAT LAKES THIS AFTERNOON. THIS SHORTWAVE WILL
TRACK THROUGH AS THE JET STREAM LIFTS NORTH...PUTTING SOUTHEAST
MICHIGAN IN THE RIGHT ENTRANCE REGION PRODUCING UPPER LEVEL
DIVERGENCE. SOUTHEAST MICHIGAN WILL REMAIN IN THE WARM SECTOR
TODAY...AS MUCAPE VALUES CLIMB TO 1000 TO 1500 J/KG. IN ADDITION TO
THE INSTABILITY...BULK SHEAR VALUES AROUND 40 KNOTS WILL LEAD TO AN
INCREASED THREAT FOR DAMAGING WINDS AND LARGE HAIL. ACROSS THE FAR
SOUTHEASTERN CWA...TURNING IN THE LOWEST LEVELS OF THE ATMOSPHERE
WILL LEAD TO AN ENHANCED THREAT FOR ISOLATED TORNADOES DEEPER IN THE
WARM SECTOR WITH 0-1 KM BULK SHEAR VALUES OF 25 KNOTS AND 200 J/KG
OF 0-3 KM CAPE. OVERALL THE SEVERE WEATHER THREAT TODAY LOOKS A BIT
BETTER THAN YESTERDAY GIVEN THE DYNAMICS INVOLVED WITH THE MAIN
CONVECTIVE MODE EXPECTED TO BE SEVERAL ROUNDS OF MESOSCALE
CONVECTIVE SYSTEMS TRACKING THROUGH THE CENTRAL GREAT LAKES THIS
AFTERNOON AND INTO THE EVENING HOURS. THE AREA REMAINS IN THE SLIGHT
RISK FOR SEVERE WEATHER PER THE SPC SWODY1 DISCUSSION WHICH LOOKS
SOLID GIVEN THE ABOVE FACTORS.
WITH THE AREA STILL IN THE WARM SECTOR...HIGH TEMPERATURES ARE
EXPECTED TO HIT 80 OR BETTER SOUTH OF M-59...WITH MID TO UPPER 70S
ACROSS THE NORTH WITH MORE CLOUD COVER AND CLOSER PROXIMITY TO THE
WARM FRONT.
THE THREAT FOR SHOWERS AND THUNDERSTORMS CONTINUES OVERNIGHT AS THE
AFOREMENTIONED TROUGH APPROACHES THE CENTRAL GREAT LAKES AND THE
SURFACE LOW TRACKS ALONG THE WARM FRONT...TURNING IT INTO A COLD
FRONT AS IT SLOWLY SINKS SOUTH. WITH THE LOSS OF INSTABILITY AND
SUPPORT FROM THE JET STREAM...SEVERE WEATHER THREAT WILL DIMINISH
MARKEDLY AFTER MIDNIGHT...WITH SHOWERS AND ISOLATED THUNDERSTORMS
EXPECTED LATE TONIGHT. WITH THE COLD FRONT DRAPED OVER THE CENTER OF
THE CWA...LOWS WILL RANGE FROM AROUND 50 ACROSS THE NORTH TO AROUND
60 ACROSS THE FAR SOUTH...SOUTH OF THE COLD FRONT. RAIN CHANCES WILL
MAINLY BE ALONG AND BEHIND THE FRONT...WITH THE BEST CHANCES ACROSS
THE NORTH AND A DIMINISHED CHANCE LATE TONIGHT ACROSS THE SOUTHERN
CWA AHEAD OF THE COLD FRONT.
LONG TERM...THURSDAY THROUGH TUESDAY
BY THURSDAY MORNING...THE CUTOFF LOW THAT SAT OVER THE NORTHERN
PLAINS FOR THE LAST SEVERAL DAYS WILL GET ABSORBED BY A NORTHERN
STREAM TROUGH DIGGING SOUTHWARD THROUGH MANITOBA/ONTARIO. A COLD
FRONT WILL PASS THROUGH LOWER MI THURSDAY AFTERNOON THEN THE UPPER
LEVEL TROUGH AXIS WILL PASS THROUGH MI THURSDAY EVENING RIGHT BEHIND
A STRONGER COLD FRONT. THIS FRONT WILL USHER IN A MUCH COLDER AND
DRIER AIRMASS AS A LARGE AND STRONG CANADIAN SFC HIGH PRESSURE
SYSTEM BUILDS SOUTHWARD THROUGH THE GREAT LAKES AND TOWARD THE EAST
COAST. THIS WILL PUT AN END TO THE PRECIP CHANCES FOR SE MI FOR A
WHILE...AT LEAST THROUGH THE HOLIDAY WEEKEND.
THURSDAY LOOKS TO START OFF WET WITH A DRYING/COOLING TREND THROUGH
THE DAY AS THE FIRST COLD FRONT DROPS THROUGH THE STATE. SHOWERS
WILL PERSIST THROUGH THE EVENING AS MODELS IN GOOD AGREEMENT WITH A
BAND OF HIGHER THETA E WRAPPING AROUND THE ELONGATED SFC LOW OVER
SOUTHERN ONTARIO/QUEBEC. THERE IS A SMALL RISK OF THUNDERSTORMS FOR
EXTREME SOUTHERN MI JUST SOUTH OF THE COLD FRONT AS MODELS CONTINUE
TO INDICATE SOME INSTABILITY ALONG THE FRONT. FOR THE MOST PART WE
WILL SHOWERS WITH A CHANCE OF THUNDER THROUGH THE MORNING...THEN
AFTER THE FROPA SHOWERS WILL TAPER OFF THROUGH THE LATE EVENING FROM
NW TO SE AS THE SECOND COLD FRONT DROPS THROUGH. PWATS WILL DROP
FROM ABOUT 1.1 INCHES THURSDAY MORNING TO 0.25 INCHES FRIDAY
MORNING. LIKEWISE...850MB TEMPS WILL DROP FROM AROUND +10C TO AROUND
0C FOR THE SAME PERIODS. THURSDAYS HIGH TEMPS WILL OCCUR EARLY IN
THE DAY AHEAD OF THE FIRST COLD FRONT. TEMPS WILL FALL THROUGH THE
REST OF THE DAY AND NIGHT. CLOUDS SHOULD CLEAR OUT FAIRLY QUICKLY
AFTER MIDNIGHT THURSDAY NIGHT ALLOWING TEMPS TO DROP OFF INTO THE
UPPER 30S.
FOR FRIDAY AND BEYOND THE STORY BECOMES DRY AND COOL WITH A SLIGHT
WARMING TREND. FRIDAY NIGHT WILL AGAIN BE FAIRLY COOL...DIPPING DOWN
TO AROUND 40 WITH HIGHS ONLY AROUND 60. BUT AS TROUGHS SET UP OVER
BOTH COASTS...AMPLIFICATION OF A RIDGE ACROSS THE CENTRAL CONUS WILL
LEAD TO HEIGHTS BUILDING SLOWLY THROUGH THE WEEKEND. MODEL SOLUTIONS
START TO STRAY FROM EACH OTHER EARLY NEXT WEEK IN HOW THEY WANT TO
HANDLE THE NEXT SYSTEM BUT CONFIDENCE IS PRETTY GOOD THAT THE STRONG
SFC RIDGE WILL KEEP THE WARM FRONT TO OUR SOUTH AND KEEP US DRY
UNTIL TUESDAY.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND TONIGHT AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. LINGERING DENSE FOG IS EXPECTED ACROSS NORTHERN
LAKE HURON EARLY THIS MORNING...BEFORE MIXING OUT. EXPANDED THE
DENSE FOG ADVISORY A SEGMENT SOUTH GIVEN LAND AND SHIP OBSERVATIONS
ACROSS THE NORTHERN LAKE HURON REGION. WINDS WILL SHIFT TO THE NORTH
ACROSS ALL WATERS BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD
FRONT PUSH OFF TO THE EAST. THESE CONDITIONS WILL PUSH WINDS AND
WAVES CLOSE TO SMALL CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
DESPITE THE PROXIMITY TO HEADLINE CRITERIA...WILL HOLD OFF ON
HEADLINES FOR THURSDAY AT THIS TIME. HIGH PRESSURE WILL BUILD IN
ACROSS THE GREAT LAKES ON FRIDAY...BRINGING QUIET WEATHER AND
COOLER TEMPERATURES TO THE REGION.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....MM
UPDATE.......MM
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 221436
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1036 AM EDT WED MAY 22 2013
.UPDATE...
OVERCAST CONDITIONS ACROSS THE REGION HAVE LIMITED HEATING AND
DESTABILIZATION EARLY TODAY...BUT THERE ARE STILL SEVERAL OTHER
FACTORS TO KEEP SEVERE WEATHER MENTION IN THE FORECAST TODAY.
VISIBLE SATELLITE AND SFC OBS SHOW THE COLD FRONT AS A SHARP
CLEARING LINE AND DROP IN DEWPOINTS ROUGHLY ALONG THE MISSISSIPPI
RIVER FROM WI TO TN. EAST OF THE FRONT FROM ORD TO CVG THERE IS
ANOTHER CLEARING FEATURE THAT IS NEAR THE LOCATION OF A VORTICITY
MAXIMUM/SHORTWAVE ENERGY THAT IS BEING EJECTED NORTHEAST FROM THE
LOWER MS VALLEY. LOCAL HI-RES MODELS AND 12Z NAM SHOWING INITIATION
IN THE SE MI AREA AROUND 18-19Z AHEAD OF THE COLD FRONT/TRIPLE POINT
WITH SEVERE THREATS COMING TO AN END BY 00Z. ONE CAVEAT TO THAT IS
POSSIBLE ADDL CONVECTION IN THE SAGINAW VALLEY WHERE THE TRAILING
SFC LOW WILL BE CO-LOCATED WITH ANOTHER SHORTWAVE AND WOULD HAVE
BETTER UPPER LEVEL DIVERGENCE DUE TO JET ORIENTATION.
SMALL ADJUSTMENTS WERE MADE TO LOWER MAX TEMPS AND ALSO OVERNIGHT
POPS AS THE ENVIRONMENT WILL BE RECOVERING BEFORE NEXT FROPA
EARLY THURS.
&&
.AVIATION...ISSUED 727 AM EDT WED MAY 22 2013
//DISCUSSION...
SCATTERED SHOWERS WILL AFFECT THE TAF SITES EARLY THIS MORNING...AS
EVIDENCED BY RADAR REFLECTIVITY. ALTHOUGH A FEW RUMBLES OF THUNDER
ARE POSSIBLE...THEIR COVERAGE EARLY THIS MORNING IS TOO ISOLATED TO
PUT IN THE TAFS. MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO ARRIVE LATER THIS MORNING AND INTO THE AFTERNOON AS AN
UPPER LEVEL SHORT WAVE LIFTS INTO THE REGION FROM THE SOUTHWEST.
CONSIDERABLE UNCERTAINTY EXITS AT THIS TIME WITH RESPECT TO BOTH
TIMING AND COVERAGE OF THUNDERSTORMS THIS AFTERNOON. HOWEVER THERE
IS ENOUGH CONFIDENCE TO PLACE A TEMPO GROUP IN MOST OF THE TAF SITES
THIS AFTERNOON REPRESENTING THE BEST WINDOW FOR THUNDERSTORMS.
FURTHER NORTH AT MBS THUNDERSTORM PROBABILITIES ARE LOWER DUE TO
LOWER INSTABILITY VALUES...THEREFORE WILL CONTINUE TO LEAVE THUNDER
OUT. LATER TONIGHT THERE SHOULD BE A BREAK IN THE SHOWER ACTIVITY AS
THE SHORTWAVE TRACKS EAST...HOWEVER RAIN IS EXPECTED TO CONTINUE AT
MBS AS THE WARM FRONT STARTS TO SINK SOUTH AS A COLD FRONT OVER THE
SAGINAW VALLEY.
FOR DTW...SCATTERED SHOWERS ARE EXPECTED TO TRANSITION TO MORE
WIDESPREAD ACTIVITY LATER THIS MORNING WITH THUNDERSTORMS POSSIBLE
LATER THIS AFTERNOON AND INTO THE EVENING HOURS. BEST CHANCE FOR
THUNDER IS IN THE 17-21Z TIME FRAME...HOWEVER THUNDER IS POSSIBLE
PRETTY MUCH ALL DAY.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF THUNDERSTORMS THIS
AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 337 AM EDT WED MAY 22 2013
SHORT TERM...TODAY AND TONIGHT
THE LARGE MID LEVEL CLOSED OFF LOW THAT HAS BEEN PARKED OVER THE
NORTHERN PLAINS WILL MAKE ITS WAY EAST TODAY AND TONIGHT. THE LOW
WILL BEGIN TO MERGE WITH A LARGER AREA OF LOW PRESSURE OVER HUDSON
BAY AND TRANSITION FROM A CLOSED OFF LOW TO A POSITIVELY TILTED
TROUGH AS IT MAKES ITS WAY TOWARD THE WESTERN GREAT LAKES
TODAY...AND EVENTUALLY OVER THE CENTRAL GREAT LAKES TONIGHT. BEFORE
THE LOW TRACKS OVER THE CENTRAL GREAT LAKES...A PIECE OF SHORTWAVE
ENERGY CURRENTLY SPINNING OVER EASTERN OKLAHOMA WILL LIFT NORTHEAST
THROUGH THE CENTRAL GREAT LAKES THIS AFTERNOON. THIS SHORTWAVE WILL
TRACK THROUGH AS THE JET STREAM LIFTS NORTH...PUTTING SOUTHEAST
MICHIGAN IN THE RIGHT ENTRANCE REGION PRODUCING UPPER LEVEL
DIVERGENCE. SOUTHEAST MICHIGAN WILL REMAIN IN THE WARM SECTOR
TODAY...AS MUCAPE VALUES CLIMB TO 1000 TO 1500 J/KG. IN ADDITION TO
THE INSTABILITY...BULK SHEAR VALUES AROUND 40 KNOTS WILL LEAD TO AN
INCREASED THREAT FOR DAMAGING WINDS AND LARGE HAIL. ACROSS THE FAR
SOUTHEASTERN CWA...TURNING IN THE LOWEST LEVELS OF THE ATMOSPHERE
WILL LEAD TO AN ENHANCED THREAT FOR ISOLATED TORNADOES DEEPER IN THE
WARM SECTOR WITH 0-1 KM BULK SHEAR VALUES OF 25 KNOTS AND 200 J/KG
OF 0-3 KM CAPE. OVERALL THE SEVERE WEATHER THREAT TODAY LOOKS A BIT
BETTER THAN YESTERDAY GIVEN THE DYNAMICS INVOLVED WITH THE MAIN
CONVECTIVE MODE EXPECTED TO BE SEVERAL ROUNDS OF MESOSCALE
CONVECTIVE SYSTEMS TRACKING THROUGH THE CENTRAL GREAT LAKES THIS
AFTERNOON AND INTO THE EVENING HOURS. THE AREA REMAINS IN THE SLIGHT
RISK FOR SEVERE WEATHER PER THE SPC SWODY1 DISCUSSION WHICH LOOKS
SOLID GIVEN THE ABOVE FACTORS.
WITH THE AREA STILL IN THE WARM SECTOR...HIGH TEMPERATURES ARE
EXPECTED TO HIT 80 OR BETTER SOUTH OF M-59...WITH MID TO UPPER 70S
ACROSS THE NORTH WITH MORE CLOUD COVER AND CLOSER PROXIMITY TO THE
WARM FRONT.
THE THREAT FOR SHOWERS AND THUNDERSTORMS CONTINUES OVERNIGHT AS THE
AFOREMENTIONED TROUGH APPROACHES THE CENTRAL GREAT LAKES AND THE
SURFACE LOW TRACKS ALONG THE WARM FRONT...TURNING IT INTO A COLD
FRONT AS IT SLOWLY SINKS SOUTH. WITH THE LOSS OF INSTABILITY AND
SUPPORT FROM THE JET STREAM...SEVERE WEATHER THREAT WILL DIMINISH
MARKEDLY AFTER MIDNIGHT...WITH SHOWERS AND ISOLATED THUNDERSTORMS
EXPECTED LATE TONIGHT. WITH THE COLD FRONT DRAPED OVER THE CENTER OF
THE CWA...LOWS WILL RANGE FROM AROUND 50 ACROSS THE NORTH TO AROUND
60 ACROSS THE FAR SOUTH...SOUTH OF THE COLD FRONT. RAIN CHANCES WILL
MAINLY BE ALONG AND BEHIND THE FRONT...WITH THE BEST CHANCES ACROSS
THE NORTH AND A DIMINISHED CHANCE LATE TONIGHT ACROSS THE SOUTHERN
CWA AHEAD OF THE COLD FRONT.
LONG TERM...THURSDAY THROUGH TUESDAY
BY THURSDAY MORNING...THE CUTOFF LOW THAT SAT OVER THE NORTHERN
PLAINS FOR THE LAST SEVERAL DAYS WILL GET ABSORBED BY A NORTHERN
STREAM TROUGH DIGGING SOUTHWARD THROUGH MANITOBA/ONTARIO. A COLD
FRONT WILL PASS THROUGH LOWER MI THURSDAY AFTERNOON THEN THE UPPER
LEVEL TROUGH AXIS WILL PASS THROUGH MI THURSDAY EVENING RIGHT BEHIND
A STRONGER COLD FRONT. THIS FRONT WILL USHER IN A MUCH COLDER AND
DRIER AIRMASS AS A LARGE AND STRONG CANADIAN SFC HIGH PRESSURE
SYSTEM BUILDS SOUTHWARD THROUGH THE GREAT LAKES AND TOWARD THE EAST
COAST. THIS WILL PUT AN END TO THE PRECIP CHANCES FOR SE MI FOR A
WHILE...AT LEAST THROUGH THE HOLIDAY WEEKEND.
THURSDAY LOOKS TO START OFF WET WITH A DRYING/COOLING TREND THROUGH
THE DAY AS THE FIRST COLD FRONT DROPS THROUGH THE STATE. SHOWERS
WILL PERSIST THROUGH THE EVENING AS MODELS IN GOOD AGREEMENT WITH A
BAND OF HIGHER THETA E WRAPPING AROUND THE ELONGATED SFC LOW OVER
SOUTHERN ONTARIO/QUEBEC. THERE IS A SMALL RISK OF THUNDERSTORMS FOR
EXTREME SOUTHERN MI JUST SOUTH OF THE COLD FRONT AS MODELS CONTINUE
TO INDICATE SOME INSTABILITY ALONG THE FRONT. FOR THE MOST PART WE
WILL SHOWERS WITH A CHANCE OF THUNDER THROUGH THE MORNING...THEN
AFTER THE FROPA SHOWERS WILL TAPER OFF THROUGH THE LATE EVENING FROM
NW TO SE AS THE SECOND COLD FRONT DROPS THROUGH. PWATS WILL DROP
FROM ABOUT 1.1 INCHES THURSDAY MORNING TO 0.25 INCHES FRIDAY
MORNING. LIKEWISE...850MB TEMPS WILL DROP FROM AROUND +10C TO AROUND
0C FOR THE SAME PERIODS. THURSDAYS HIGH TEMPS WILL OCCUR EARLY IN
THE DAY AHEAD OF THE FIRST COLD FRONT. TEMPS WILL FALL THROUGH THE
REST OF THE DAY AND NIGHT. CLOUDS SHOULD CLEAR OUT FAIRLY QUICKLY
AFTER MIDNIGHT THURSDAY NIGHT ALLOWING TEMPS TO DROP OFF INTO THE
UPPER 30S.
FOR FRIDAY AND BEYOND THE STORY BECOMES DRY AND COOL WITH A SLIGHT
WARMING TREND. FRIDAY NIGHT WILL AGAIN BE FAIRLY COOL...DIPPING DOWN
TO AROUND 40 WITH HIGHS ONLY AROUND 60. BUT AS TROUGHS SET UP OVER
BOTH COASTS...AMPLIFICATION OF A RIDGE ACROSS THE CENTRAL CONUS WILL
LEAD TO HEIGHTS BUILDING SLOWLY THROUGH THE WEEKEND. MODEL SOLUTIONS
START TO STRAY FROM EACH OTHER EARLY NEXT WEEK IN HOW THEY WANT TO
HANDLE THE NEXT SYSTEM BUT CONFIDENCE IS PRETTY GOOD THAT THE STRONG
SFC RIDGE WILL KEEP THE WARM FRONT TO OUR SOUTH AND KEEP US DRY
UNTIL TUESDAY.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND TONIGHT AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. LINGERING DENSE FOG IS EXPECTED ACROSS NORTHERN
LAKE HURON EARLY THIS MORNING...BEFORE MIXING OUT. EXPANDED THE
DENSE FOG ADVISORY A SEGMENT SOUTH GIVEN LAND AND SHIP OBSERVATIONS
ACROSS THE NORTHERN LAKE HURON REGION. WINDS WILL SHIFT TO THE NORTH
ACROSS ALL WATERS BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD
FRONT PUSH OFF TO THE EAST. THESE CONDITIONS WILL PUSH WINDS AND
WAVES CLOSE TO SMALL CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
DESPITE THE PROXIMITY TO HEADLINE CRITERIA...WILL HOLD OFF ON
HEADLINES FOR THURSDAY AT THIS TIME. HIGH PRESSURE WILL BUILD IN
ACROSS THE GREAT LAKES ON FRIDAY...BRINGING QUIET WEATHER AND
COOLER TEMPERATURES TO THE REGION.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......MM
AVIATION.....KURIMSKI
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 221127
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
727 AM EDT WED MAY 22 2013
.AVIATION...
//DISCUSSION...
SCATTERED SHOWERS WILL AFFECT THE TAF SITES EARLY THIS MORNING...AS
EVIDENCED BY RADAR REFLECTIVITY. ALTHOUGH A FEW RUMBLES OF THUNDER
ARE POSSIBLE...THEIR COVERAGE EARLY THIS MORNING IS TOO ISOLATED TO
PUT IN THE TAFS. MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO ARRIVE LATER THIS MORNING AND INTO THE AFTERNOON AS AN
UPPER LEVEL SHORT WAVE LIFTS INTO THE REGION FROM THE SOUTHWEST.
CONSIDERABLE UNCERTAINTY EXITS AT THIS TIME WITH RESPECT TO BOTH
TIMING AND COVERAGE OF THUNDERSTORMS THIS AFTERNOON. HOWEVER THERE
IS ENOUGH CONFIDENCE TO PLACE A TEMPO GROUP IN MOST OF THE TAF SITES
THIS AFTERNOON REPRESENTING THE BEST WINDOW FOR THUNDERSTORMS.
FURTHER NORTH AT MBS THUNDERSTORM PROBABILITIES ARE LOWER DUE TO
LOWER INSTABILITY VALUES...THEREFORE WILL CONTINUE TO LEAVE THUNDER
OUT. LATER TONIGHT THERE SHOULD BE A BREAK IN THE SHOWER ACTIVITY AS
THE SHORTWAVE TRACKS EAST...HOWEVER RAIN IS EXPECTED TO CONTINUE AT
MBS AS THE WARM FRONT STARTS TO SINK SOUTH AS A COLD FRONT OVER THE
SAGINAW VALLEY.
FOR DTW...SCATTERED SHOWERS ARE EXPECTED TO TRANSITION TO MORE
WIDESPREAD ACTIVITY LATER THIS MORNING WITH THUNDERSTORMS POSSIBLE
LATER THIS AFTERNOON AND INTO THE EVENING HOURS. BEST CHANCE FOR
THUNDER IS IN THE 17-21Z TIME FRAME...HOWEVER THUNDER IS POSSIBLE
PRETTY MUCH ALL DAY.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN TIMING AND COVERAGE OF THUNDERSTORMS THIS
AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 337 AM EDT WED MAY 22 2013
SHORT TERM...TODAY AND TONIGHT
THE LARGE MID LEVEL CLOSED OFF LOW THAT HAS BEEN PARKED OVER THE
NORTHERN PLAINS WILL MAKE ITS WAY EAST TODAY AND TONIGHT. THE LOW
WILL BEGIN TO MERGE WITH A LARGER AREA OF LOW PRESSURE OVER HUDSON
BAY AND TRANSITION FROM A CLOSED OFF LOW TO A POSITIVELY TILTED
TROUGH AS IT MAKES ITS WAY TOWARD THE WESTERN GREAT LAKES
TODAY...AND EVENTUALLY OVER THE CENTRAL GREAT LAKES TONIGHT. BEFORE
THE LOW TRACKS OVER THE CENTRAL GREAT LAKES...A PIECE OF SHORTWAVE
ENERGY CURRENTLY SPINNING OVER EASTERN OKLAHOMA WILL LIFT NORTHEAST
THROUGH THE CENTRAL GREAT LAKES THIS AFTERNOON. THIS SHORTWAVE WILL
TRACK THROUGH AS THE JET STREAM LIFTS NORTH...PUTTING SOUTHEAST
MICHIGAN IN THE RIGHT ENTRANCE REGION PRODUCING UPPER LEVEL
DIVERGENCE. SOUTHEAST MICHIGAN WILL REMAIN IN THE WARM SECTOR
TODAY...AS MUCAPE VALUES CLIMB TO 1000 TO 1500 J/KG. IN ADDITION TO
THE INSTABILITY...BULK SHEAR VALUES AROUND 40 KNOTS WILL LEAD TO AN
INCREASED THREAT FOR DAMAGING WINDS AND LARGE HAIL. ACROSS THE FAR
SOUTHEASTERN CWA...TURNING IN THE LOWEST LEVELS OF THE ATMOSPHERE
WILL LEAD TO AN ENHANCED THREAT FOR ISOLATED TORNADOES DEEPER IN THE
WARM SECTOR WITH 0-1 KM BULK SHEAR VALUES OF 25 KNOTS AND 200 J/KG
OF 0-3 KM CAPE. OVERALL THE SEVERE WEATHER THREAT TODAY LOOKS A BIT
BETTER THAN YESTERDAY GIVEN THE DYNAMICS INVOLVED WITH THE MAIN
CONVECTIVE MODE EXPECTED TO BE SEVERAL ROUNDS OF MESOSCALE
CONVECTIVE SYSTEMS TRACKING THROUGH THE CENTRAL GREAT LAKES THIS
AFTERNOON AND INTO THE EVENING HOURS. THE AREA REMAINS IN THE SLIGHT
RISK FOR SEVERE WEATHER PER THE SPC SWODY1 DISCUSSION WHICH LOOKS
SOLID GIVEN THE ABOVE FACTORS.
WITH THE AREA STILL IN THE WARM SECTOR...HIGH TEMPERATURES ARE
EXPECTED TO HIT 80 OR BETTER SOUTH OF M-59...WITH MID TO UPPER 70S
ACROSS THE NORTH WITH MORE CLOUD COVER AND CLOSER PROXIMITY TO THE
WARM FRONT.
THE THREAT FOR SHOWERS AND THUNDERSTORMS CONTINUES OVERNIGHT AS THE
AFOREMENTIONED TROUGH APPROACHES THE CENTRAL GREAT LAKES AND THE
SURFACE LOW TRACKS ALONG THE WARM FRONT...TURNING IT INTO A COLD
FRONT AS IT SLOWLY SINKS SOUTH. WITH THE LOSS OF INSTABILITY AND
SUPPORT FROM THE JET STREAM...SEVERE WEATHER THREAT WILL DIMINISH
MARKEDLY AFTER MIDNIGHT...WITH SHOWERS AND ISOLATED THUNDERSTORMS
EXPECTED LATE TONIGHT. WITH THE COLD FRONT DRAPED OVER THE CENTER OF
THE CWA...LOWS WILL RANGE FROM AROUND 50 ACROSS THE NORTH TO AROUND
60 ACROSS THE FAR SOUTH...SOUTH OF THE COLD FRONT. RAIN CHANCES WILL
MAINLY BE ALONG AND BEHIND THE FRONT...WITH THE BEST CHANCES ACROSS
THE NORTH AND A DIMINISHED CHANCE LATE TONIGHT ACROSS THE SOUTHERN
CWA AHEAD OF THE COLD FRONT.
LONG TERM...THURSDAY THROUGH TUESDAY
BY THURSDAY MORNING...THE CUTOFF LOW THAT SAT OVER THE NORTHERN
PLAINS FOR THE LAST SEVERAL DAYS WILL GET ABSORBED BY A NORTHERN
STREAM TROUGH DIGGING SOUTHWARD THROUGH MANITOBA/ONTARIO. A COLD
FRONT WILL PASS THROUGH LOWER MI THURSDAY AFTERNOON THEN THE UPPER
LEVEL TROUGH AXIS WILL PASS THROUGH MI THURSDAY EVENING RIGHT BEHIND
A STRONGER COLD FRONT. THIS FRONT WILL USHER IN A MUCH COLDER AND
DRIER AIRMASS AS A LARGE AND STRONG CANADIAN SFC HIGH PRESSURE
SYSTEM BUILDS SOUTHWARD THROUGH THE GREAT LAKES AND TOWARD THE EAST
COAST. THIS WILL PUT AN END TO THE PRECIP CHANCES FOR SE MI FOR A
WHILE...AT LEAST THROUGH THE HOLIDAY WEEKEND.
THURSDAY LOOKS TO START OFF WET WITH A DRYING/COOLING TREND THROUGH
THE DAY AS THE FIRST COLD FRONT DROPS THROUGH THE STATE. SHOWERS
WILL PERSIST THROUGH THE EVENING AS MODELS IN GOOD AGREEMENT WITH A
BAND OF HIGHER THETA E WRAPPING AROUND THE ELONGATED SFC LOW OVER
SOUTHERN ONTARIO/QUEBEC. THERE IS A SMALL RISK OF THUNDERSTORMS FOR
EXTREME SOUTHERN MI JUST SOUTH OF THE COLD FRONT AS MODELS CONTINUE
TO INDICATE SOME INSTABILITY ALONG THE FRONT. FOR THE MOST PART WE
WILL SHOWERS WITH A CHANCE OF THUNDER THROUGH THE MORNING...THEN
AFTER THE FROPA SHOWERS WILL TAPER OFF THROUGH THE LATE EVENING FROM
NW TO SE AS THE SECOND COLD FRONT DROPS THROUGH. PWATS WILL DROP
FROM ABOUT 1.1 INCHES THURSDAY MORNING TO 0.25 INCHES FRIDAY
MORNING. LIKEWISE...850MB TEMPS WILL DROP FROM AROUND +10C TO AROUND
0C FOR THE SAME PERIODS. THURSDAYS HIGH TEMPS WILL OCCUR EARLY IN
THE DAY AHEAD OF THE FIRST COLD FRONT. TEMPS WILL FALL THROUGH THE
REST OF THE DAY AND NIGHT. CLOUDS SHOULD CLEAR OUT FAIRLY QUICKLY
AFTER MIDNIGHT THURSDAY NIGHT ALLOWING TEMPS TO DROP OFF INTO THE
UPPER 30S.
FOR FRIDAY AND BEYOND THE STORY BECOMES DRY AND COOL WITH A SLIGHT
WARMING TREND. FRIDAY NIGHT WILL AGAIN BE FAIRLY COOL...DIPPING DOWN
TO AROUND 40 WITH HIGHS ONLY AROUND 60. BUT AS TROUGHS SET UP OVER
BOTH COASTS...AMPLIFICATION OF A RIDGE ACROSS THE CENTRAL CONUS WILL
LEAD TO HEIGHTS BUILDING SLOWLY THROUGH THE WEEKEND. MODEL SOLUTIONS
START TO STRAY FROM EACH OTHER EARLY NEXT WEEK IN HOW THEY WANT TO
HANDLE THE NEXT SYSTEM BUT CONFIDENCE IS PRETTY GOOD THAT THE STRONG
SFC RIDGE WILL KEEP THE WARM FRONT TO OUR SOUTH AND KEEP US DRY
UNTIL TUESDAY.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND TONIGHT AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. LINGERING DENSE FOG IS EXPECTED ACROSS NORTHERN
LAKE HURON EARLY THIS MORNING...BEFORE MIXING OUT. EXPANDED THE
DENSE FOG ADVISORY A SEGMENT SOUTH GIVEN LAND AND SHIP OBSERVATIONS
ACROSS THE NORTHERN LAKE HURON REGION. WINDS WILL SHIFT TO THE NORTH
ACROSS ALL WATERS BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD
FRONT PUSH OFF TO THE EAST. THESE CONDITIONS WILL PUSH WINDS AND
WAVES CLOSE TO SMALL CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
DESPITE THE PROXIMITY TO HEADLINE CRITERIA...WILL HOLD OFF ON
HEADLINES FOR THURSDAY AT THIS TIME. HIGH PRESSURE WILL BUILD IN
ACROSS THE GREAT LAKES ON FRIDAY...BRINGING QUIET WEATHER AND
COOLER TEMPERATURES TO THE REGION.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
DENSE FOG ADVISORY...LHZ361-LHZ362...UNTIL 8 AM WEDNESDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....KURIMSKI
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 220737
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
337 AM EDT WED MAY 22 2013
.SHORT TERM...TODAY AND TONIGHT
THE LARGE MID LEVEL CLOSED OFF LOW THAT HAS BEEN PARKED OVER THE
NORTHERN PLAINS WILL MAKE ITS WAY EAST TODAY AND TONIGHT. THE LOW
WILL BEGIN TO MERGE WITH A LARGER AREA OF LOW PRESSURE OVER HUDSON
BAY AND TRANSITION FROM A CLOSED OFF LOW TO A POSITIVELY TILTED
TROUGH AS IT MAKES ITS WAY TOWARD THE WESTERN GREAT LAKES
TODAY...AND EVENTUALLY OVER THE CENTRAL GREAT LAKES TONIGHT. BEFORE
THE LOW TRACKS OVER THE CENTRAL GREAT LAKES...A PIECE OF SHORTWAVE
ENERGY CURRENTLY SPINNING OVER EASTERN OKLAHOMA WILL LIFT NORTHEAST
THROUGH THE CENTRAL GREAT LAKES THIS AFTERNOON. THIS SHORTWAVE WILL
TRACK THROUGH AS THE JET STREAM LIFTS NORTH...PUTTING SOUTHEAST
MICHIGAN IN THE RIGHT ENTRANCE REGION PRODUCING UPPER LEVEL
DIVERGENCE. SOUTHEAST MICHIGAN WILL REMAIN IN THE WARM SECTOR
TODAY...AS MUCAPE VALUES CLIMB TO 1000 TO 1500 J/KG. IN ADDITION TO
THE INSTABILITY...BULK SHEAR VALUES AROUND 40 KNOTS WILL LEAD TO AN
INCREASED THREAT FOR DAMAGING WINDS AND LARGE HAIL. ACROSS THE FAR
SOUTHEASTERN CWA...TURNING IN THE LOWEST LEVELS OF THE ATMOSPHERE
WILL LEAD TO AN ENHANCED THREAT FOR ISOLATED TORNADOES DEEPER IN THE
WARM SECTOR WITH 0-1 KM BULK SHEAR VALUES OF 25 KNOTS AND 200 J/KG
OF 0-3 KM CAPE. OVERALL THE SEVERE WEATHER THREAT TODAY LOOKS A BIT
BETTER THAN YESTERDAY GIVEN THE DYNAMICS INVOLVED WITH THE MAIN
CONVECTIVE MODE EXPECTED TO BE SEVERAL ROUNDS OF MESOSCALE
CONVECTIVE SYSTEMS TRACKING THROUGH THE CENTRAL GREAT LAKES THIS
AFTERNOON AND INTO THE EVENING HOURS. THE AREA REMAINS IN THE SLIGHT
RISK FOR SEVERE WEATHER PER THE SPC SWODY1 DISCUSSION WHICH LOOKS
SOLID GIVEN THE ABOVE FACTORS.
WITH THE AREA STILL IN THE WARM SECTOR...HIGH TEMPERATURES ARE
EXPECTED TO HIT 80 OR BETTER SOUTH OF M-59...WITH MID TO UPPER 70S
ACROSS THE NORTH WITH MORE CLOUD COVER AND CLOSER PROXIMITY TO THE
WARM FRONT.
THE THREAT FOR SHOWERS AND THUNDERSTORMS CONTINUES OVERNIGHT AS THE
AFOREMENTIONED TROUGH APPROACHES THE CENTRAL GREAT LAKES AND THE
SURFACE LOW TRACKS ALONG THE WARM FRONT...TURNING IT INTO A COLD
FRONT AS IT SLOWLY SINKS SOUTH. WITH THE LOSS OF INSTABILITY AND
SUPPORT FROM THE JET STREAM...SEVERE WEATHER THREAT WILL DIMINISH
MARKEDLY AFTER MIDNIGHT...WITH SHOWERS AND ISOLATED THUNDERSTORMS
EXPECTED LATE TONIGHT. WITH THE COLD FRONT DRAPED OVER THE CENTER OF
THE CWA...LOWS WILL RANGE FROM AROUND 50 ACROSS THE NORTH TO AROUND
60 ACROSS THE FAR SOUTH...SOUTH OF THE COLD FRONT. RAIN CHANCES WILL
MAINLY BE ALONG AND BEHIND THE FRONT...WITH THE BEST CHANCES ACROSS
THE NORTH AND A DIMINISHED CHANCE LATE TONIGHT ACROSS THE SOUTHERN
CWA AHEAD OF THE COLD FRONT.
&&
.LONG TERM...THURSDAY THROUGH TUESDAY
BY THURSDAY MORNING...THE CUTOFF LOW THAT SAT OVER THE NORTHERN
PLAINS FOR THE LAST SEVERAL DAYS WILL GET ABSORBED BY A NORTHERN
STREAM TROUGH DIGGING SOUTHWARD THROUGH MANITOBA/ONTARIO. A COLD
FRONT WILL PASS THROUGH LOWER MI THURSDAY AFTERNOON THEN THE UPPER
LEVEL TROUGH AXIS WILL PASS THROUGH MI THURSDAY EVENING RIGHT BEHIND
A STRONGER COLD FRONT. THIS FRONT WILL USHER IN A MUCH COLDER AND
DRIER AIRMASS AS A LARGE AND STRONG CANADIAN SFC HIGH PRESSURE
SYSTEM BUILDS SOUTHWARD THROUGH THE GREAT LAKES AND TOWARD THE EAST
COAST. THIS WILL PUT AN END TO THE PRECIP CHANCES FOR SE MI FOR A
WHILE...AT LEAST THROUGH THE HOLIDAY WEEKEND.
THURSDAY LOOKS TO START OFF WET WITH A DRYING/COOLING TREND THROUGH
THE DAY AS THE FIRST COLD FRONT DROPS THROUGH THE STATE. SHOWERS
WILL PERSIST THROUGH THE EVENING AS MODELS IN GOOD AGREEMENT WITH A
BAND OF HIGHER THETA E WRAPPING AROUND THE ELONGATED SFC LOW OVER
SOUTHERN ONTARIO/QUEBEC. THERE IS A SMALL RISK OF THUNDERSTORMS FOR
EXTREME SOUTHERN MI JUST SOUTH OF THE COLD FRONT AS MODELS CONTINUE
TO INDICATE SOME INSTABILITY ALONG THE FRONT. FOR THE MOST PART WE
WILL SHOWERS WITH A CHANCE OF THUNDER THROUGH THE MORNING...THEN
AFTER THE FROPA SHOWERS WILL TAPER OFF THROUGH THE LATE EVENING FROM
NW TO SE AS THE SECOND COLD FRONT DROPS THROUGH. PWATS WILL DROP
FROM ABOUT 1.1 INCHES THURSDAY MORNING TO 0.25 INCHES FRIDAY
MORNING. LIKEWISE...850MB TEMPS WILL DROP FROM AROUND +10C TO AROUND
0C FOR THE SAME PERIODS. THURSDAYS HIGH TEMPS WILL OCCUR EARLY IN
THE DAY AHEAD OF THE FIRST COLD FRONT. TEMPS WILL FALL THROUGH THE
REST OF THE DAY AND NIGHT. CLOUDS SHOULD CLEAR OUT FAIRLY QUICKLY
AFTER MIDNIGHT THURSDAY NIGHT ALLOWING TEMPS TO DROP OFF INTO THE
UPPER 30S.
FOR FRIDAY AND BEYOND THE STORY BECOMES DRY AND COOL WITH A SLIGHT
WARMING TREND. FRIDAY NIGHT WILL AGAIN BE FAIRLY COOL...DIPPING DOWN
TO AROUND 40 WITH HIGHS ONLY AROUND 60. BUT AS TROUGHS SET UP OVER
BOTH COASTS...AMPLIFICATION OF A RIDGE ACROSS THE CENTRAL CONUS WILL
LEAD TO HEIGHTS BUILDING SLOWLY THROUGH THE WEEKEND. MODEL SOLUTIONS
START TO STRAY FROM EACH OTHER EARLY NEXT WEEK IN HOW THEY WANT TO
HANDLE THE NEXT SYSTEM BUT CONFIDENCE IS PRETTY GOOD THAT THE STRONG
SFC RIDGE WILL KEEP THE WARM FRONT TO OUR SOUTH AND KEEP US DRY
UNTIL TUESDAY.
&&
.MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND TONIGHT AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. LINGERING DENSE FOG IS EXPECTED ACROSS NORTHERN
LAKE HURON EARLY THIS MORNING...BEFORE MIXING OUT. EXPANDED THE
DENSE FOG ADVISORY A SEGMENT SOUTH GIVEN LAND AND SHIP OBSERVATIONS
ACROSS THE NORTHERN LAKE HURON REGION. WINDS WILL SHIFT TO THE NORTH
ACROSS ALL WATERS BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD
FRONT PUSH OFF TO THE EAST. THESE CONDITIONS WILL PUSH WINDS AND
WAVES CLOSE TO SMALL CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
DESPITE THE PROXIMITY TO HEADLINE CRITERIA...WILL HOLD OFF ON
HEADLINES FOR THURSDAY AT THIS TIME. HIGH PRESSURE WILL BUILD IN
ACROSS THE GREAT LAKES ON FRIDAY...BRINGING QUIET WEATHER AND
COOLER TEMPERATURES TO THE REGION.
&&
.AVIATION...ISSUED 1144 PM EDT TUE MAY 21 2013
//DISCUSSION...
RESIDUAL CONVECTION EARLY THIS MORNING WILL BE LOW TOPPED SHOWERS
COURTESY OF WARM AIR ALOFT. TEMPS ALOFT ARE EXPECTED TO COOL DURING
THE COURSE OF THE MORNING. THIS ALONG WITH MOISTURE ADVECTION FROM
THE SOUTHWEST WILL PROVIDE A CHANCE OF SCATTERED THUNDERSTORMS
TOWARD DAYBREAK WED. MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO ARRIVE AFTER 12Z AS AN UPPER LEVEL SHORT WAVE LIFTS INTO
THE REGION FROM THE SOUTHWEST. CONSIDERABLE UNCERTAINTY EXITS AT
THIS TIME WITH RESPECT TO BOTH TIMING AND COVERAGE OF THUNDERSTORMS
ON WEDNESDAY.
FOR DTW...LATE EVENING SHOWERS WILL PUSH OFF TO THE NORTHEAST EARLY
IN THE TAF PERIOD. ATTENTION NOW TURNS TO DEVELOPING THUNDERSTORMS
OVER NRN IL AND NRN IND...WHICH COULD POSSIBLY LIFT INTO METRO
DETROIT AROUND DAYBREAK.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE IN TIMING AND COVERAGE OF THUNDERSTORMS THIS
MORNING AND AFTERNOON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
DENSE FOG ADVISORY...LHZ361...UNTIL 6 AM WEDNESDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
AVIATION.....SC
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 220344
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1144 PM EDT TUE MAY 21 2013
.AVIATION...
//DISCUSSION...
RESIDUAL CONVECTION EARLY THIS MORNING WILL BE LOW TOPPED SHOWERS
COURTESY OF WARM AIR ALOFT. TEMPS ALOFT ARE EXPECTED TO COOL DURING
THE COURSE OF THE MORNING. THIS ALONG WITH MOISTURE ADVECTION FROM
THE SOUTHWEST WILL PROVIDE A CHANCE OF SCATTERED THUNDERSTORMS
TOWARD DAYBREAK WED. MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO ARRIVE AFTER 12Z AS AN UPPER LEVEL SHORT WAVE LIFTS INTO
THE REGION FROM THE SOUTHWEST. CONSIDERABLE UNCERTAINTY EXITS AT
THIS TIME WITH RESPECT TO BOTH TIMING AND COVERAGE OF THUNDERSTORMS
ON WEDNESDAY.
FOR DTW...LATE EVENING SHOWERS WILL PUSH OFF TO THE NORTHEAST EARLY
IN THE TAF PERIOD. ATTENTION NOW TURNS TO DEVELOPING THUNDERSTORMS
OVER NRN IL AND NRN IND...WHICH COULD POSSIBLY LIFT INTO METRO
DETROIT AROUND DAYBREAK.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE IN TIMING AND COVERAGE OF THUNDERSTORMS THIS
MORNING AND AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 906 PM EDT TUE MAY 21 2013
UPDATE...
ASSIDE FROM SOME SHALLOW CONVECTION ALONG A MID LEVEL THETA E
AXIS SOUTH OF THE I-94 CORRIDOR...SE MI IS PRECIP FREE. THE 00Z
DTX SOUNDING SHOWED STRONG CAPPING IN THE 500-550 MB LAYER...MUCH
STRONGER THAN THE CAPPING OBSERVED AT 18Z. THE SEVERE STORM WHICH
MOVED ACROSS NORTHERN TUSCOLA COUNTY EARLIER IN THE EVENING
LIKELY RODE THE EDGE OF THIS MID LEVEL WARM POOL. THIS CAPPING
INVERSION AND LACK OF UPPER SUPPORT WILL WARRANT FURTHER LOWERING
OF POPS TONIGHT. THE EXCEPTION OF COURSE WILL BE SOUTH OF THE I-94
CORRIDOR IN LIGHT OF CURRENT RADAR TRENDS.
PREV DISCUSSION...ISSUED 350 PM EDT TUE MAY 21 2013
SHORT TERM...THROUGH TONIGHT
SOUTHEAST MICHIGAN REMAINS FIRMLY POSITIONED WITHIN DEEP MID LEVEL
SOUTHWEST FLOW WORKING AROUND THE EASTERN EXTENSION OF THE PREVALENT
CLOSED LOW STILL HOVERING OVER EASTERN SD. FOCUS THROUGH THE
EVENING REMAINS ON CONVECTIVE POTENTIAL AND ANY CORRESPONDING SEVERE
RISK. DEFINED LOW LEVEL INSTABILITY GRADIENT AND BETTER LAPSE RATE
ENVIRONMENT THAT EMERGED EARLIER TODAY UNDER FULL SUN MODULATING NOW
WITH THE PROGRESSIVE PASSAGE OF A REMNANT MCV. RECENT AREA
OBSERVATIONS AND SPC MESOANALYSIS SHOW THE EFFECTIVE DOWNTURN IN THE
AMBIENT INSTABILITY (MLCAPE LESS 500 J/KG) PROMPTED BY SOME DEGREE
OF BOUNDARY LAYER DRYING AND SLIGHT WARMING THROUGH THE MID LEVELS.
18Z DTX UPPER AIR SOUNDING SAMPLING THE LEAD EDGE OF THIS
TRANSITIONING ENVIRONMENT SHOWS A FAIRLY SHALLOW UNSTABLE LAYER...
MARKED BY WEAK CAPPING. THE PRESENCE OF JUST SOME AGITATED HIGH
BASED CU AND SCATTERED SHOWERS THUS FAR SUGGESTS FORMIDABLE MID
LEVEL WARMTH DOES EXIST TO HINDER THE POTENTIAL FOR BETTER UPDRAFT
GROWTH. OTHER AREA OF FOCUS EXISTS WITHIN THE COMBINATION OF THE
ENHANCED LOW LEVEL CONVERGENCE ZONE SLIPPING OFF THE LEE OF LAKE
MICHIGAN AND THE EASTWARD PROPAGATING SOME DEGREE OF MOISTURE
POOLING ALONG THIS BOUNDARY IS SUPPORTING CONVECTIVE DEVELOPMENT.
THERE IS AT LEAST A LOW PROBABILITY FOR THIS ACTIVITY TO ATTAIN
ENOUGH FORWARD MOMENTUM TO WORK INTO NORTHERN SECTIONS OF THE AREA
YET TODAY. ALL THIS POINTS TOWARD RETAINING JUST A LOW POP THROUGH
THE EARLY EVENING PERIOD. SHOULD A MORE ROBUST UPDRAFT MANAGE TO
WORK THROUGH THE CAP...AN ISOLATED SEVERE WIND/HAIL RISK DOES EXIST
THROUGH THIS EVENING GIVEN SUFFICIENT DEEP LAYER SHEAR TO RETAIN A
MORE ORGANIZED STRUCTURE.
GENERAL SUBSIDENCE IN THE WAKE OF THE MCV WILL PROVIDE A PERIOD OF
DRY AND RELATIVELY STABLE CONDITIONS HEADING INTO TONIGHT. HOWEVER
A RENEWED CORRIDOR OF THETA-E ADVECTION WORKING ALONG THE EASTERN
EDGE OF THE UPPER JET AXIS OVER THE MIDWEST WILL WORK OVERNIGHT.
THIS PROCESS MAY PROVIDE ENOUGH MID LEVEL DESTABILIZATION TO SUPPORT
SCATTERED SHOWER/THUNDERSTORM DEVELOPMENT...ESPECIALLY IF ARRIVING
ATTENDANT TO A WEAK PV FILAMENT AND/OR REMNANT MCV STREAMING OUT OF
THE MID MS VALLEY.
FORECAST LOWS FOR TONIGHT THAT OF GENERAL AIRMASS PERSISTENCE...
READINGS AGAIN IN THE LOW TO MID 60S.
LONG TERM...
A STRONG NORTHERN STREAM TROUGH CURRENTLY DROPPING SOUTH THROUGH
HUDSON BAY WILL LEAD TO A PATTERN SHIFT OVER THE NEXT COUPLE OF
DAYS...AS THE LARGE UPPER LEVEL LOW CENTERED OVER EASTERN SOUTH
DAKOTA SHOULD BE ABLE TO BE PICKED UPPED AND ABSORBED WITH THE
PREVIOUSLY MENTIONED NORTHERN STREAM TROUGH. MEANWHILE...MORE OF A
SHORT TERM PRESSING MATTER IS THE POTENT SHORTWAVE COMING OUT OF THE
PANHANDLE OF TEXAS...WHICH WILL BE CATAPULTED TO THE NORTHEAST AND
ABSORBED WITHIN THE NORTHERN PLAINS CIRCULATION. GOOD HEIGHT FALLS
SPREADING INTO THE GREAT LAKES REGION TOMORROW...WITH THE MAX CENTER
TRACKING THROUGH SOUTHERN LAKE MICHIGAN NORTHEAST INTO SAGINAW
BAY...WHICH SHOULD MATCH UP FAIRLY WELL WITH THE MAIN SURFACE LOW
TRACK. THE 12Z UKMET IS THE STRONGEST/DEEPEST WITH THE SURFACE
WAVE...WITH THE REGIONAL GEM A BIT WEAKER...BUT STILL IN THE SAME
BALL PARK. THE WIND FIELDS TOMORROW WILL BE CONDUCIVE FOR SEVERE
WEATHER (BOWING LINE SEGMENTS)...AS 850 MB WINDS ADVERTISED AROUND
40 KNOTS...WITH EVEN MORE IMPRESSIVE 55-60 KNOT 700 MB JET SLICING
THROUGH SOUTHEAST MICHIGAN DURING PEAK HEATING. LOW LEVEL WIND SHEAR
(0-1 KM) ALSO LOOKS PRETTY GOOD WITH 25 KNOTS TO POSSIBLY AS HIGH AS
30 KNOTS...LEADING TO A TORNADIC THREAT...ALONG AND SOUTH OF M-59
WHICH LOOKS TO BE THE PRIME LOCATION OF THE TRIPLE POINT. AS
USUAL...INSTABILITY IS ALWAYS THE DECIDING FACTOR. GOOD ISENTROPIC
ASCENT IN THE MORNING COUPLED WITH SOLID INSTABILITY (SHOWALTER
INDEX OF -2 TO -4) WILL LIKELY LEAD TO SHOWERS AND THUNDERSTORMS IN
THE MORNING HOURS...WHICH WILL TEND TO LIMIT OUR DIURNAL
INSTABILITY. HOWEVER...ANY BREAKS/LULL IN ACTIVITY OR ADVECTIVE
PROCESS (SURFACE DEW PTS POTENTIALLY CLIMBING INTO UPPER 60S) AS WE
HEAD INTO THE AFTERNOON...COULD BE SUFFICIENT TO GENERATE CAPES ON
THE ORDER OF 1000 J/KG OR BETTER...WHICH WILL PROBABLY BE THE MARKER
TO PRODUCE SEVERE WEATHER WITH THE PREVIOUSLY DESCRIBED AMOUNT OF
WIND SHEAR. ALSO OF NOTE...IS THE MAJORITY OF CAPE IS IN THE LOW/MID
LEVELS (850-500 MB)...ALSO A POSITIVE FOR SEVERE WEATHER AND
ISOLATED TORNADO. STILL...WIDESPREAD CONVECTION THROUGH THE DAY
OVER SOUTHEAST MICHIGAN OR FARTHER SOUTH OVER THE NORTHERN OHIO
VALLEY COULD LIMIT THE INSTABILITY TO THE MORE MANAGEABLE 500 J/KG
OR LESS...PREVENTING ORGANIZED SEVERE STORMS/STRONGER WINDS FROM
DESCENDING TO GROUND.
UPPER LEVEL TROUGH AXIS TRACKING INTO THE CENTRAL GREAT LAKES ON
THURSDAY...WITH ANOTHER COLD FRONT SWINGING THROUGH EARLY IN THE DAY
SHOULD BE SHOULD BE SUFFICIENT TO TOUCH OF SHOWERS WITH DECENT
TRAILING 850-700 MB THETA-E RIDGE AXIS MOVING THROUGH AND EQUALLY
IMPORTANT STRONG AND SHARP DRY PUSH INTO NORTHERN LOWER MICHIGAN BY
DAYS END. MUCH COLDER AIR WILL BE FILTERING IN THROUGH THE DAY...AS
850 MB TEMPS FORECASTED TO FALL TO NEAR ZERO TOWARD 00Z
FRIDAY...THUS HIGHS SHOULD NOT BE MUCH HIGHER THAN THE MORNINGS LOW
(UPPER 50S).
NORTHWEST UPPER LEVEL CONFLUENT FLOW THEN LOOKS TO BE DOMINATING OUR
WEATHER FRIDAY AND INTO THE WEEKEND...ALLOWING A STRONG HIGH FOR
(LATE MAY STANDARDS) TO BUILD INTO THE GREAT LAKES REGION...INTO
MONDAY...PER 12Z EURO. BEST RADIATORS (THUMB REGION...ETC) STAND
GOOD CHANCE OF FALLING INTO THE 30S AT NIGHT WITH FROST POSSIBLE.
ASSUMING THERE IS NOT A HUGE CU UP DURING THE DAYTIME HOURS...WOULD
EXPECTED MAXES TO REACH AND EXCEED 60 DEGREES AS WE MIX ABOVE 850 MB
WITH LATE MAY ISOLATION.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE THROUGH WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
DENSE FOG ADVISORY...LHZ361...UNTIL 6 AM WEDNESDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....SC
UPDATE.......SC
SHORT TERM...MR
LONG TERM....SF
MARINE.......MR
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 220106
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
906 PM EDT TUE MAY 21 2013
.UPDATE...
ASSIDE FROM SOME SHALLOW CONVECTION ALONG A MID LEVEL THETA E
AXIS SOUTH OF THE I-94 CORRIDOR...SE MI IS PRECIP FREE. THE 00Z
DTX SOUNDING SHOWED STRONG CAPPING IN THE 500-550 MB LAYER...MUCH
STRONGER THAN THE CAPPING OBSERVED AT 18Z. THE SEVERE STORM WHICH
MOVED ACROSS NORTHERN TUSCOLA COUNTY EARLIER IN THE EVENING
LIKELY RODE THE EDGE OF THIS MID LEVEL WARM POOL. THIS CAPPING
INVERSION AND LACK OF UPPER SUPPORT WILL WARRANT FURTHER LOWERING
OF POPS TONIGHT. THE EXCEPTION OF COURSE WILL BE SOUTH OF THE I-94
CORRIDOR IN LIGHT OF CURRENT RADAR TRENDS.
&&
.AVIATION...ISSUED 734 PM EDT TUE MAY 21 2013
//DISCUSSION...
THERE HAS BEEN SOME ENHANCED CONVERGENCE FROM NRN INDIANA INTO THE
THUMB REGION. THIS MAY CONTINUE TO FIRE OFF ISOLATED THUNDERSTORMS.
TOO LOW OF CHANCES AT THIS TIME TO INCLUDE MENTION OF THUNDER IN
THIS EVENINGS TAFS. MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO ARRIVE AFTER 12Z WED AS AN UPPER LEVEL SHORT WAVE LIFTS
INTO THE REGION FROM THE SOUTHWEST. CONSIDERABLE UNCERTAINTY EXITS
AT THIS TIME WITH RESPECT TO BOTH TIMING AND COVERAGE OF
THUNDERSTORMS ON WEDNESDAY.
FOR DTW...THERE HAS BEEN SOME ENHANCED CONVECTIVE DEVELOPMENT IN THE
VICINITY OF METRO. CONDITIONS IN AND AROUND METRO ARE A LITTLE BIT
MORE STABLE...WHICH MAY KEEP ANY EVENING CONVECTION LIMITED TO JUST
SOME ISOLATED SHOWERS.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE IN THUNDERSTORM OCCURRENCE TONIGHT TONIGHT THROUGH
WEDNESDAY.
&&
.PREV DISCUSSION...ISSUED 350 PM EDT TUE MAY 21 2013
SHORT TERM...THROUGH TONIGHT
SOUTHEAST MICHIGAN REMAINS FIRMLY POSITIONED WITHIN DEEP MID LEVEL
SOUTHWEST FLOW WORKING AROUND THE EASTERN EXTENSION OF THE PREVALENT
CLOSED LOW STILL HOVERING OVER EASTERN SD. FOCUS THROUGH THE
EVENING REMAINS ON CONVECTIVE POTENTIAL AND ANY CORRESPONDING SEVERE
RISK. DEFINED LOW LEVEL INSTABILITY GRADIENT AND BETTER LAPSE RATE
ENVIRONMENT THAT EMERGED EARLIER TODAY UNDER FULL SUN MODULATING NOW
WITH THE PROGRESSIVE PASSAGE OF A REMNANT MCV. RECENT AREA
OBSERVATIONS AND SPC MESOANALYSIS SHOW THE EFFECTIVE DOWNTURN IN THE
AMBIENT INSTABILITY (MLCAPE LESS 500 J/KG) PROMPTED BY SOME DEGREE
OF BOUNDARY LAYER DRYING AND SLIGHT WARMING THROUGH THE MID LEVELS.
18Z DTX UPPER AIR SOUNDING SAMPLING THE LEAD EDGE OF THIS
TRANSITIONING ENVIRONMENT SHOWS A FAIRLY SHALLOW UNSTABLE LAYER...
MARKED BY WEAK CAPPING. THE PRESENCE OF JUST SOME AGITATED HIGH
BASED CU AND SCATTERED SHOWERS THUS FAR SUGGESTS FORMIDABLE MID
LEVEL WARMTH DOES EXIST TO HINDER THE POTENTIAL FOR BETTER UPDRAFT
GROWTH. OTHER AREA OF FOCUS EXISTS WITHIN THE COMBINATION OF THE
ENHANCED LOW LEVEL CONVERGENCE ZONE SLIPPING OFF THE LEE OF LAKE
MICHIGAN AND THE EASTWARD PROPAGATING SOME DEGREE OF MOISTURE
POOLING ALONG THIS BOUNDARY IS SUPPORTING CONVECTIVE DEVELOPMENT.
THERE IS AT LEAST A LOW PROBABILITY FOR THIS ACTIVITY TO ATTAIN
ENOUGH FORWARD MOMENTUM TO WORK INTO NORTHERN SECTIONS OF THE AREA
YET TODAY. ALL THIS POINTS TOWARD RETAINING JUST A LOW POP THROUGH
THE EARLY EVENING PERIOD. SHOULD A MORE ROBUST UPDRAFT MANAGE TO
WORK THROUGH THE CAP...AN ISOLATED SEVERE WIND/HAIL RISK DOES EXIST
THROUGH THIS EVENING GIVEN SUFFICIENT DEEP LAYER SHEAR TO RETAIN A
MORE ORGANIZED STRUCTURE.
GENERAL SUBSIDENCE IN THE WAKE OF THE MCV WILL PROVIDE A PERIOD OF
DRY AND RELATIVELY STABLE CONDITIONS HEADING INTO TONIGHT. HOWEVER
A RENEWED CORRIDOR OF THETA-E ADVECTION WORKING ALONG THE EASTERN
EDGE OF THE UPPER JET AXIS OVER THE MIDWEST WILL WORK OVERNIGHT.
THIS PROCESS MAY PROVIDE ENOUGH MID LEVEL DESTABILIZATION TO SUPPORT
SCATTERED SHOWER/THUNDERSTORM DEVELOPMENT...ESPECIALLY IF ARRIVING
ATTENDANT TO A WEAK PV FILAMENT AND/OR REMNANT MCV STREAMING OUT OF
THE MID MS VALLEY.
FORECAST LOWS FOR TONIGHT THAT OF GENERAL AIRMASS PERSISTENCE...
READINGS AGAIN IN THE LOW TO MID 60S.
LONG TERM...
A STRONG NORTHERN STREAM TROUGH CURRENTLY DROPPING SOUTH THROUGH
HUDSON BAY WILL LEAD TO A PATTERN SHIFT OVER THE NEXT COUPLE OF
DAYS...AS THE LARGE UPPER LEVEL LOW CENTERED OVER EASTERN SOUTH
DAKOTA SHOULD BE ABLE TO BE PICKED UPPED AND ABSORBED WITH THE
PREVIOUSLY MENTIONED NORTHERN STREAM TROUGH. MEANWHILE...MORE OF A
SHORT TERM PRESSING MATTER IS THE POTENT SHORTWAVE COMING OUT OF THE
PANHANDLE OF TEXAS...WHICH WILL BE CATAPULTED TO THE NORTHEAST AND
ABSORBED WITHIN THE NORTHERN PLAINS CIRCULATION. GOOD HEIGHT FALLS
SPREADING INTO THE GREAT LAKES REGION TOMORROW...WITH THE MAX CENTER
TRACKING THROUGH SOUTHERN LAKE MICHIGAN NORTHEAST INTO SAGINAW
BAY...WHICH SHOULD MATCH UP FAIRLY WELL WITH THE MAIN SURFACE LOW
TRACK. THE 12Z UKMET IS THE STRONGEST/DEEPEST WITH THE SURFACE
WAVE...WITH THE REGIONAL GEM A BIT WEAKER...BUT STILL IN THE SAME
BALL PARK. THE WIND FIELDS TOMORROW WILL BE CONDUCIVE FOR SEVERE
WEATHER (BOWING LINE SEGMENTS)...AS 850 MB WINDS ADVERTISED AROUND
40 KNOTS...WITH EVEN MORE IMPRESSIVE 55-60 KNOT 700 MB JET SLICING
THROUGH SOUTHEAST MICHIGAN DURING PEAK HEATING. LOW LEVEL WIND SHEAR
(0-1 KM) ALSO LOOKS PRETTY GOOD WITH 25 KNOTS TO POSSIBLY AS HIGH AS
30 KNOTS...LEADING TO A TORNADIC THREAT...ALONG AND SOUTH OF M-59
WHICH LOOKS TO BE THE PRIME LOCATION OF THE TRIPLE POINT. AS
USUAL...INSTABILITY IS ALWAYS THE DECIDING FACTOR. GOOD ISENTROPIC
ASCENT IN THE MORNING COUPLED WITH SOLID INSTABILITY (SHOWALTER
INDEX OF -2 TO -4) WILL LIKELY LEAD TO SHOWERS AND THUNDERSTORMS IN
THE MORNING HOURS...WHICH WILL TEND TO LIMIT OUR DIURNAL
INSTABILITY. HOWEVER...ANY BREAKS/LULL IN ACTIVITY OR ADVECTIVE
PROCESS (SURFACE DEW PTS POTENTIALLY CLIMBING INTO UPPER 60S) AS WE
HEAD INTO THE AFTERNOON...COULD BE SUFFICIENT TO GENERATE CAPES ON
THE ORDER OF 1000 J/KG OR BETTER...WHICH WILL PROBABLY BE THE MARKER
TO PRODUCE SEVERE WEATHER WITH THE PREVIOUSLY DESCRIBED AMOUNT OF
WIND SHEAR. ALSO OF NOTE...IS THE MAJORITY OF CAPE IS IN THE LOW/MID
LEVELS (850-500 MB)...ALSO A POSITIVE FOR SEVERE WEATHER AND
ISOLATED TORNADO. STILL...WIDESPREAD CONVECTION THROUGH THE DAY
OVER SOUTHEAST MICHIGAN OR FARTHER SOUTH OVER THE NORTHERN OHIO
VALLEY COULD LIMIT THE INSTABILITY TO THE MORE MANAGEABLE 500 J/KG
OR LESS...PREVENTING ORGANIZED SEVERE STORMS/STRONGER WINDS FROM
DESCENDING TO GROUND.
UPPER LEVEL TROUGH AXIS TRACKING INTO THE CENTRAL GREAT LAKES ON
THURSDAY...WITH ANOTHER COLD FRONT SWINGING THROUGH EARLY IN THE DAY
SHOULD BE SHOULD BE SUFFICIENT TO TOUCH OF SHOWERS WITH DECENT
TRAILING 850-700 MB THETA-E RIDGE AXIS MOVING THROUGH AND EQUALLY
IMPORTANT STRONG AND SHARP DRY PUSH INTO NORTHERN LOWER MICHIGAN BY
DAYS END. MUCH COLDER AIR WILL BE FILTERING IN THROUGH THE DAY...AS
850 MB TEMPS FORECASTED TO FALL TO NEAR ZERO TOWARD 00Z
FRIDAY...THUS HIGHS SHOULD NOT BE MUCH HIGHER THAN THE MORNINGS LOW
(UPPER 50S).
NORTHWEST UPPER LEVEL CONFLUENT FLOW THEN LOOKS TO BE DOMINATING OUR
WEATHER FRIDAY AND INTO THE WEEKEND...ALLOWING A STRONG HIGH FOR
(LATE MAY STANDARDS) TO BUILD INTO THE GREAT LAKES REGION...INTO
MONDAY...PER 12Z EURO. BEST RADIATORS (THUMB REGION...ETC) STAND
GOOD CHANCE OF FALLING INTO THE 30S AT NIGHT WITH FROST POSSIBLE.
ASSUMING THERE IS NOT A HUGE CU UP DURING THE DAYTIME HOURS...WOULD
EXPECTED MAXES TO REACH AND EXCEED 60 DEGREES AS WE MIX ABOVE 850 MB
WITH LATE MAY ISOLATION.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE THROUGH WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...
DENSE FOG ADVISORY...LHZ361...UNTIL 6 AM WEDNESDAY.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......SC
AVIATION.....SC
SHORT TERM...MR
LONG TERM....SF
MARINE.......MR
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 212334
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
734 PM EDT TUE MAY 21 2013
.AVIATION...
//DISCUSSION...
THERE HAS BEEN SOME ENHANCED CONVERGENCE FROM NRN INDIANA INTO THE
THUMB REGION. THIS MAY CONTINUE TO FIRE OFF ISOLATED THUNDERSTORMS.
TOO LOW OF CHANCES AT THIS TIME TO INCLUDE MENTION OF THUNDER IN
THIS EVENINGS TAFS. MORE WIDESPREAD SHOWERS AND THUNDERSTORMS ARE
EXPECTED TO ARRIVE AFTER 12Z WED AS AN UPPER LEVEL SHORT WAVE LIFTS
INTO THE REGION FROM THE SOUTHWEST. CONSIDERABLE UNCERTAINTY EXITS
AT THIS TIME WITH RESPECT TO BOTH TIMING AND COVERAGE OF
THUNDERSTORMS ON WEDNESDAY.
FOR DTW...THERE HAS BEEN SOME ENHANCED CONVECTIVE DEVELOPMENT IN THE
VICINITY OF METRO. CONDITIONS IN AND AROUND METRO ARE A LITTLE BIT
MORE STABLE...WHICH MAY KEEP ANY EVENING CONVECTION LIMITED TO JUST
SOME ISOLATED SHOWERS.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE IN THUNDERSTORM OCCURRENCE TONIGHT TONIGHT THROUGH
WEDNESDAY.
&&
.PREV DISCUSSION...ISSUED 350 PM EDT TUE MAY 21 2013
SHORT TERM...THROUGH TONIGHT
SOUTHEAST MICHIGAN REMAINS FIRMLY POSITIONED WITHIN DEEP MID LEVEL
SOUTHWEST FLOW WORKING AROUND THE EASTERN EXTENSION OF THE PREVALENT
CLOSED LOW STILL HOVERING OVER EASTERN SD. FOCUS THROUGH THE
EVENING REMAINS ON CONVECTIVE POTENTIAL AND ANY CORRESPONDING SEVERE
RISK. DEFINED LOW LEVEL INSTABILITY GRADIENT AND BETTER LAPSE RATE
ENVIRONMENT THAT EMERGED EARLIER TODAY UNDER FULL SUN MODULATING NOW
WITH THE PROGRESSIVE PASSAGE OF A REMNANT MCV. RECENT AREA
OBSERVATIONS AND SPC MESOANALYSIS SHOW THE EFFECTIVE DOWNTURN IN THE
AMBIENT INSTABILITY (MLCAPE LESS 500 J/KG) PROMPTED BY SOME DEGREE
OF BOUNDARY LAYER DRYING AND SLIGHT WARMING THROUGH THE MID LEVELS.
18Z DTX UPPER AIR SOUNDING SAMPLING THE LEAD EDGE OF THIS
TRANSITIONING ENVIRONMENT SHOWS A FAIRLY SHALLOW UNSTABLE LAYER...
MARKED BY WEAK CAPPING. THE PRESENCE OF JUST SOME AGITATED HIGH
BASED CU AND SCATTERED SHOWERS THUS FAR SUGGESTS FORMIDABLE MID
LEVEL WARMTH DOES EXIST TO HINDER THE POTENTIAL FOR BETTER UPDRAFT
GROWTH. OTHER AREA OF FOCUS EXISTS WITHIN THE COMBINATION OF THE
ENHANCED LOW LEVEL CONVERGENCE ZONE SLIPPING OFF THE LEE OF LAKE
MICHIGAN AND THE EASTWARD PROPAGATING SOME DEGREE OF MOISTURE
POOLING ALONG THIS BOUNDARY IS SUPPORTING CONVECTIVE DEVELOPMENT.
THERE IS AT LEAST A LOW PROBABILITY FOR THIS ACTIVITY TO ATTAIN
ENOUGH FORWARD MOMENTUM TO WORK INTO NORTHERN SECTIONS OF THE AREA
YET TODAY. ALL THIS POINTS TOWARD RETAINING JUST A LOW POP THROUGH
THE EARLY EVENING PERIOD. SHOULD A MORE ROBUST UPDRAFT MANAGE TO
WORK THROUGH THE CAP...AN ISOLATED SEVERE WIND/HAIL RISK DOES EXIST
THROUGH THIS EVENING GIVEN SUFFICIENT DEEP LAYER SHEAR TO RETAIN A
MORE ORGANIZED STRUCTURE.
GENERAL SUBSIDENCE IN THE WAKE OF THE MCV WILL PROVIDE A PERIOD OF
DRY AND RELATIVELY STABLE CONDITIONS HEADING INTO TONIGHT. HOWEVER
A RENEWED CORRIDOR OF THETA-E ADVECTION WORKING ALONG THE EASTERN
EDGE OF THE UPPER JET AXIS OVER THE MIDWEST WILL WORK OVERNIGHT.
THIS PROCESS MAY PROVIDE ENOUGH MID LEVEL DESTABILIZATION TO SUPPORT
SCATTERED SHOWER/THUNDERSTORM DEVELOPMENT...ESPECIALLY IF ARRIVING
ATTENDANT TO A WEAK PV FILAMENT AND/OR REMNANT MCV STREAMING OUT OF
THE MID MS VALLEY.
FORECAST LOWS FOR TONIGHT THAT OF GENERAL AIRMASS PERSISTENCE...
READINGS AGAIN IN THE LOW TO MID 60S.
LONG TERM...
A STRONG NORTHERN STREAM TROUGH CURRENTLY DROPPING SOUTH THROUGH
HUDSON BAY WILL LEAD TO A PATTERN SHIFT OVER THE NEXT COUPLE OF
DAYS...AS THE LARGE UPPER LEVEL LOW CENTERED OVER EASTERN SOUTH
DAKOTA SHOULD BE ABLE TO BE PICKED UPPED AND ABSORBED WITH THE
PREVIOUSLY MENTIONED NORTHERN STREAM TROUGH. MEANWHILE...MORE OF A
SHORT TERM PRESSING MATTER IS THE POTENT SHORTWAVE COMING OUT OF THE
PANHANDLE OF TEXAS...WHICH WILL BE CATAPULTED TO THE NORTHEAST AND
ABSORBED WITHIN THE NORTHERN PLAINS CIRCULATION. GOOD HEIGHT FALLS
SPREADING INTO THE GREAT LAKES REGION TOMORROW...WITH THE MAX CENTER
TRACKING THROUGH SOUTHERN LAKE MICHIGAN NORTHEAST INTO SAGINAW
BAY...WHICH SHOULD MATCH UP FAIRLY WELL WITH THE MAIN SURFACE LOW
TRACK. THE 12Z UKMET IS THE STRONGEST/DEEPEST WITH THE SURFACE
WAVE...WITH THE REGIONAL GEM A BIT WEAKER...BUT STILL IN THE SAME
BALL PARK. THE WIND FIELDS TOMORROW WILL BE CONDUCIVE FOR SEVERE
WEATHER (BOWING LINE SEGMENTS)...AS 850 MB WINDS ADVERTISED AROUND
40 KNOTS...WITH EVEN MORE IMPRESSIVE 55-60 KNOT 700 MB JET SLICING
THROUGH SOUTHEAST MICHIGAN DURING PEAK HEATING. LOW LEVEL WIND SHEAR
(0-1 KM) ALSO LOOKS PRETTY GOOD WITH 25 KNOTS TO POSSIBLY AS HIGH AS
30 KNOTS...LEADING TO A TORNADIC THREAT...ALONG AND SOUTH OF M-59
WHICH LOOKS TO BE THE PRIME LOCATION OF THE TRIPLE POINT. AS
USUAL...INSTABILITY IS ALWAYS THE DECIDING FACTOR. GOOD ISENTROPIC
ASCENT IN THE MORNING COUPLED WITH SOLID INSTABILITY (SHOWALTER
INDEX OF -2 TO -4) WILL LIKELY LEAD TO SHOWERS AND THUNDERSTORMS IN
THE MORNING HOURS...WHICH WILL TEND TO LIMIT OUR DIURNAL
INSTABILITY. HOWEVER...ANY BREAKS/LULL IN ACTIVITY OR ADVECTIVE
PROCESS (SURFACE DEW PTS POTENTIALLY CLIMBING INTO UPPER 60S) AS WE
HEAD INTO THE AFTERNOON...COULD BE SUFFICIENT TO GENERATE CAPES ON
THE ORDER OF 1000 J/KG OR BETTER...WHICH WILL PROBABLY BE THE MARKER
TO PRODUCE SEVERE WEATHER WITH THE PREVIOUSLY DESCRIBED AMOUNT OF
WIND SHEAR. ALSO OF NOTE...IS THE MAJORITY OF CAPE IS IN THE LOW/MID
LEVELS (850-500 MB)...ALSO A POSITIVE FOR SEVERE WEATHER AND
ISOLATED TORNADO. STILL...WIDESPREAD CONVECTION THROUGH THE DAY
OVER SOUTHEAST MICHIGAN OR FARTHER SOUTH OVER THE NORTHERN OHIO
VALLEY COULD LIMIT THE INSTABILITY TO THE MORE MANAGEABLE 500 J/KG
OR LESS...PREVENTING ORGANIZED SEVERE STORMS/STRONGER WINDS FROM
DESCENDING TO GROUND.
UPPER LEVEL TROUGH AXIS TRACKING INTO THE CENTRAL GREAT LAKES ON
THURSDAY...WITH ANOTHER COLD FRONT SWINGING THROUGH EARLY IN THE DAY
SHOULD BE SHOULD BE SUFFICIENT TO TOUCH OF SHOWERS WITH DECENT
TRAILING 850-700 MB THETA-E RIDGE AXIS MOVING THROUGH AND EQUALLY
IMPORTANT STRONG AND SHARP DRY PUSH INTO NORTHERN LOWER MICHIGAN BY
DAYS END. MUCH COLDER AIR WILL BE FILTERING IN THROUGH THE DAY...AS
850 MB TEMPS FORECASTED TO FALL TO NEAR ZERO TOWARD 00Z
FRIDAY...THUS HIGHS SHOULD NOT BE MUCH HIGHER THAN THE MORNINGS LOW
(UPPER 50S).
NORTHWEST UPPER LEVEL CONFLUENT FLOW THEN LOOKS TO BE DOMINATING OUR
WEATHER FRIDAY AND INTO THE WEEKEND...ALLOWING A STRONG HIGH FOR
(LATE MAY STANDARDS) TO BUILD INTO THE GREAT LAKES REGION...INTO
MONDAY...PER 12Z EURO. BEST RADIATORS (THUMB REGION...ETC) STAND
GOOD CHANCE OF FALLING INTO THE 30S AT NIGHT WITH FROST POSSIBLE.
ASSUMING THERE IS NOT A HUGE CU UP DURING THE DAYTIME HOURS...WOULD
EXPECTED MAXES TO REACH AND EXCEED 60 DEGREES AS WE MIX ABOVE 850 MB
WITH LATE MAY ISOLATION.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE THROUGH WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....SC
SHORT TERM...MR
LONG TERM....SF
MARINE.......MR
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 211950
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
350 PM EDT TUE MAY 21 2013
.SHORT TERM...THROUGH TONIGHT
SOUTHEAST MICHIGAN REMAINS FIRMLY POSITIONED WITHIN DEEP MID LEVEL
SOUTHWEST FLOW WORKING AROUND THE EASTERN EXTENSION OF THE PREVALENT
CLOSED LOW STILL HOVERING OVER EASTERN SD. FOCUS THROUGH THE
EVENING REMAINS ON CONVECTIVE POTENTIAL AND ANY CORRESPONDING SEVERE
RISK. DEFINED LOW LEVEL INSTABILITY GRADIENT AND BETTER LAPSE RATE
ENVIRONMENT THAT EMERGED EARLIER TODAY UNDER FULL SUN MODULATING NOW
WITH THE PROGRESSIVE PASSAGE OF A REMNANT MCV. RECENT AREA
OBSERVATIONS AND SPC MESOANALYSIS SHOW THE EFFECTIVE DOWNTURN IN THE
AMBIENT INSTABILITY (MLCAPE LESS 500 J/KG) PROMPTED BY SOME DEGREE
OF BOUNDARY LAYER DRYING AND SLIGHT WARMING THROUGH THE MID LEVELS.
18Z DTX UPPER AIR SOUNDING SAMPLING THE LEAD EDGE OF THIS
TRANSITIONING ENVIRONMENT SHOWS A FAIRLY SHALLOW UNSTABLE LAYER...
MARKED BY WEAK CAPPING. THE PRESENCE OF JUST SOME AGITATED HIGH
BASED CU AND SCATTERED SHOWERS THUS FAR SUGGESTS FORMIDABLE MID
LEVEL WARMTH DOES EXIST TO HINDER THE POTENTIAL FOR BETTER UPDRAFT
GROWTH. OTHER AREA OF FOCUS EXISTS WITHIN THE COMBINATION OF THE
ENHANCED LOW LEVEL CONVERGENCE ZONE SLIPPING OFF THE LEE OF LAKE
MICHIGAN AND THE EASTWARD PROPAGATING SOME DEGREE OF MOISTURE
POOLING ALONG THIS BOUNDARY IS SUPPORTING CONVECTIVE DEVELOPMENT.
THERE IS AT LEAST A LOW PROBABILITY FOR THIS ACTIVITY TO ATTAIN
ENOUGH FORWARD MOMENTUM TO WORK INTO NORTHERN SECTIONS OF THE AREA
YET TODAY. ALL THIS POINTS TOWARD RETAINING JUST A LOW POP THROUGH
THE EARLY EVENING PERIOD. SHOULD A MORE ROBUST UPDRAFT MANAGE TO
WORK THROUGH THE CAP...AN ISOLATED SEVERE WIND/HAIL RISK DOES EXIST
THROUGH THIS EVENING GIVEN SUFFICIENT DEEP LAYER SHEAR TO RETAIN A
MORE ORGANIZED STRUCTURE.
GENERAL SUBSIDENCE IN THE WAKE OF THE MCV WILL PROVIDE A PERIOD OF
DRY AND RELATIVELY STABLE CONDITIONS HEADING INTO TONIGHT. HOWEVER
A RENEWED CORRIDOR OF THETA-E ADVECTION WORKING ALONG THE EASTERN
EDGE OF THE UPPER JET AXIS OVER THE MIDWEST WILL WORK OVERNIGHT.
THIS PROCESS MAY PROVIDE ENOUGH MID LEVEL DESTABILIZATION TO SUPPORT
SCATTERED SHOWER/THUNDERSTORM DEVELOPMENT...ESPECIALLY IF ARRIVING
ATTENDANT TO A WEAK PV FILAMENT AND/OR REMNANT MCV STREAMING OUT OF
THE MID MS VALLEY.
FORECAST LOWS FOR TONIGHT THAT OF GENERAL AIRMASS PERSISTENCE...
READINGS AGAIN IN THE LOW TO MID 60S.
&&
.LONG TERM...
A STRONG NORTHERN STREAM TROUGH CURRENTLY DROPPING SOUTH THROUGH
HUDSON BAY WILL LEAD TO A PATTERN SHIFT OVER THE NEXT COUPLE OF
DAYS...AS THE LARGE UPPER LEVEL LOW CENTERED OVER EASTERN SOUTH
DAKOTA SHOULD BE ABLE TO BE PICKED UPPED AND ABSORBED WITH THE
PREVIOUSLY MENTIONED NORTHERN STREAM TROUGH. MEANWHILE...MORE OF A
SHORT TERM PRESSING MATTER IS THE POTENT SHORTWAVE COMING OUT OF THE
PANHANDLE OF TEXAS...WHICH WILL BE CATAPULTED TO THE NORTHEAST AND
ABSORBED WITHIN THE NORTHERN PLAINS CIRCULATION. GOOD HEIGHT FALLS
SPREADING INTO THE GREAT LAKES REGION TOMORROW...WITH THE MAX CENTER
TRACKING THROUGH SOUTHERN LAKE MICHIGAN NORTHEAST INTO SAGINAW
BAY...WHICH SHOULD MATCH UP FAIRLY WELL WITH THE MAIN SURFACE LOW
TRACK. THE 12Z UKMET IS THE STRONGEST/DEEPEST WITH THE SURFACE
WAVE...WITH THE REGIONAL GEM A BIT WEAKER...BUT STILL IN THE SAME
BALL PARK. THE WIND FIELDS TOMORROW WILL BE CONDUCIVE FOR SEVERE
WEATHER (BOWING LINE SEGMENTS)...AS 850 MB WINDS ADVERTISED AROUND
40 KNOTS...WITH EVEN MORE IMPRESSIVE 55-60 KNOT 700 MB JET SLICING
THROUGH SOUTHEAST MICHIGAN DURING PEAK HEATING. LOW LEVEL WIND SHEAR
(0-1 KM) ALSO LOOKS PRETTY GOOD WITH 25 KNOTS TO POSSIBLY AS HIGH AS
30 KNOTS...LEADING TO A TORNADIC THREAT...ALONG AND SOUTH OF M-59
WHICH LOOKS TO BE THE PRIME LOCATION OF THE TRIPLE POINT. AS
USUAL...INSTABILITY IS ALWAYS THE DECIDING FACTOR. GOOD ISENTROPIC
ASCENT IN THE MORNING COUPLED WITH SOLID INSTABILITY (SHOWALTER
INDEX OF -2 TO -4) WILL LIKELY LEAD TO SHOWERS AND THUNDERSTORMS IN
THE MORNING HOURS...WHICH WILL TEND TO LIMIT OUR DIURNAL
INSTABILITY. HOWEVER...ANY BREAKS/LULL IN ACTIVITY OR ADVECTIVE
PROCESS (SURFACE DEW PTS POTENTIALLY CLIMBING INTO UPPER 60S) AS WE
HEAD INTO THE AFTERNOON...COULD BE SUFFICIENT TO GENERATE CAPES ON
THE ORDER OF 1000 J/KG OR BETTER...WHICH WILL PROBABLY BE THE MARKER
TO PRODUCE SEVERE WEATHER WITH THE PREVIOUSLY DESCRIBED AMOUNT OF
WIND SHEAR. ALSO OF NOTE...IS THE MAJORITY OF CAPE IS IN THE LOW/MID
LEVELS (850-500 MB)...ALSO A POSITIVE FOR SEVERE WEATHER AND
ISOLATED TORNADO. STILL...WIDESPREAD CONVECTION THROUGH THE DAY
OVER SOUTHEAST MICHIGAN OR FARTHER SOUTH OVER THE NORTHERN OHIO
VALLEY COULD LIMIT THE INSTABILITY TO THE MORE MANAGEABLE 500 J/KG
OR LESS...PREVENTING ORGANIZED SEVERE STORMS/STRONGER WINDS FROM
DESCENDING TO GROUND.
UPPER LEVEL TROUGH AXIS TRACKING INTO THE CENTRAL GREAT LAKES ON
THURSDAY...WITH ANOTHER COLD FRONT SWINGING THROUGH EARLY IN THE DAY
SHOULD BE SHOULD BE SUFFICIENT TO TOUCH OF SHOWERS WITH DECENT
TRAILING 850-700 MB THETA-E RIDGE AXIS MOVING THROUGH AND EQUALLY
IMPORTANT STRONG AND SHARP DRY PUSH INTO NORTHERN LOWER MICHIGAN BY
DAYS END. MUCH COLDER AIR WILL BE FILTERING IN THROUGH THE DAY...AS
850 MB TEMPS FORECASTED TO FALL TO NEAR ZERO TOWARD 00Z
FRIDAY...THUS HIGHS SHOULD NOT BE MUCH HIGHER THAN THE MORNINGS LOW
(UPPER 50S).
NORTHWEST UPPER LEVEL CONFLUENT FLOW THEN LOOKS TO BE DOMINATING OUR
WEATHER FRIDAY AND INTO THE WEEKEND...ALLOWING A STRONG HIGH FOR
(LATE MAY STANDARDS) TO BUILD INTO THE GREAT LAKES REGION...INTO
MONDAY...PER 12Z EURO. BEST RADIATORS (THUMB REGION...ETC) STAND
GOOD CHANCE OF FALLING INTO THE 30S AT NIGHT WITH FROST POSSIBLE.
ASSUMING THERE IS NOT A HUGE CU UP DURING THE DAYTIME HOURS...WOULD
EXPECTED MAXES TO REACH AND EXCEED 60 DEGREES AS WE MIX ABOVE 850 MB
WITH LATE MAY ISOLATION.
&&
.MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE THROUGH WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.AVIATION...ISSUED 117 PM EDT TUE MAY 21 2013
//DISCUSSION...
A DEEP SOUTHWEST FLOW WILL REMAIN IN PLACE ACROSS THE REGION
THROUGH THE TAF PERIOD. WHILE THIS WILL LEAVE THE LOCAL ENVIRONMENT
RELATIVELY MOIST AND UNSTABLE...PROSPECTS OF THUNDERSTORM
DEVELOPMENT REMAIN QUITE ILL-DEFINED. RECENT OBSERVATIONAL/
SATELLITE TRENDS AND MODEL GUIDANCE WOULD SUGGEST ANY POTENTIAL
DEVELOPMENT LATE THIS AFTERNOON WILL TEND TO REMAIN WIDELY
SCATTERED IN COVERAGE. A DEEPENING MIXED LAYER WILL LEAD TO SOME
SOUTHWESTERLY WIND GUSTS IN THE 20 KNOTS RANGE THROUGH PEAK HEATING.
FOR DTW...A LOW PROBABILITY DOES EXIST FOR THUNDERSTORMS TO IMPACT
THE TERMINAL LATE THIS AFTERNOON AND EVENING. HOWEVER THE POTENTIAL
NOW APPEARS TOO LIMITED GIVEN THE QUESTION OF COVERAGE TO INCLUDE
A SPECIFIC MENTION.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE IN THUNDERSTORM OCCURRANCE FROM MID AFTERNOON INTO
THE EVENING.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...MR
LONG TERM....SF
MARINE.......MR
AVIATION.....MR
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 211717
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
117 PM EDT TUE MAY 21 2013
.AVIATION...
//DISCUSSION...
A DEEP SOUTHWEST FLOW WILL REMAIN IN PLACE ACROSS THE REGION
THROUGH THE TAF PERIOD. WHILE THIS WILL LEAVE THE LOCAL ENVIRONMENT
RELATIVELY MOIST AND UNSTABLE...PROSPECTS OF THUNDERSTORM
DEVELOPMENT REMAIN QUITE ILL-DEFINED. RECENT OBSERVATIONAL/
SATELLITE TRENDS AND MODEL GUIDANCE WOULD SUGGEST ANY POTENTIAL
DEVELOPMENT LATE THIS AFTERNOON WILL TEND TO REMAIN WIDELY
SCATTERED IN COVERAGE. A DEEPENING MIXED LAYER WILL LEAD TO SOME
SOUTHWESTERLY WIND GUSTS IN THE 20 KNOTS RANGE THROUGH PEAK HEATING.
FOR DTW...A LOW PROBABILITY DOES EXIST FOR THUNDERSTORMS TO IMPACT
THE TERMINAL LATE THIS AFTERNOON AND EVENING. HOWEVER THE POTENTIAL
NOW APPEARS TOO LIMITED GIVEN THE QUESTION OF COVERAGE TO INCLUDE
A SPECIFIC MENTION.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE IN THUNDERSTORM OCCURRANCE FROM MID AFTERNOON INTO
THE EVENING.
&&
.PREV DISCUSSION...ISSUED 1013 AM EDT TUE MAY 21 2013
UPDATE...
SE MICHIGAN REMAINS LODGED WITHIN A DEEP/MOIST AND PROGRESSIVELY
DESTABILIZING SOUTHWEST FLOW LATE THIS MORNING. SEVERAL HOUR WINDOW
OF NEARLY FULL INSOLATION CERTAINLY HELPING THIS PROCESS...ALTHOUGH
THE NORTHERN EXTENSION OF THE REMNANT CLOUD DEBRIS ATTACHED TO THE
LEFTOVER WEAK PV FILAMENT STREAMING INTO WEST-CENTRAL OHIO WILL
BEGIN TO FILTERING THE HEATING COMPONENT SLIGHTLY HEADING INTO
MIDDAY. HOWEVER GIVEN CURRENT TRENDS...HIGH TEMPERATURES OF LOWER
TO MIDDLE 80S CERTAINLY ARE ATTAINABLE. THIS PROJECTS TO ROUGHLY
1500 J/KG OF MLCAPE FOR THIS AFTERNOON.
DESPITE THIS EMERGING LOW LEVEL INSTABILITY GRADIENT...DELINEATING
BOTH THE LOCATION AND SCALE OF CONVECTIVE DEVELOPMENT...BOTH
UPSTREAM AND LOCALLY...REMAINS A CHALLENGE FOR THE AFTERNOON AND
EVENING PERIOD. 12Z DTX SOUNDING AND RECENT MODEL GUIDANCE SUGGEST
SOME DEGREE OF CAPPING REMAINS IN PLACE...ALBEIT NOT NEARLY AS
STRONG AS NOTED YESTERDAY. CONVECTIVE INITIATION MAY BECOME TIED TO
ADDITIONAL WEAK SHORTWAVE ENERGY AND ON THE LEAD EDGE OF AN
EXPANDING DIFFERENTIAL HEATING ZONE WORKING ACROSS MISSOURI AND INTO
SOUTHERN ILLINOIS. RECENT HI RES MODEL GUIDANCE PROVIDE FEW
CLUES...SUGGESTING A WINDOW FOR ISOLATED/SCATTERED DISCRETE CELL
DEVELOPMENT IN THAT FAVORED 19-22Z PERIOD. GIVEN A SOLID BACKGROUND
THERMODYNAMIC ENVIRONMENT TO MAINTAIN UPDRAFT STRENGTH...THE
PRESENCE OF A SUPPORTIVELY DEEP LAYER WIND FIELD WILL MAINTAIN A
RISK OF DAMAGING WINDS AND HAIL WITH ANY CELLS THAT CAN ORGANIZE
THROUGH THE PEAK HEATING CYCLE.
MINOR UPDATE ISSUED ALREADY TO READJUST POPS THROUGH THE EVENING AND
TWEAK TEMPERATURES BASED ON RECENT TRENDS.
PREV DISCUSSION...ISSUED 738 AM EDT TUE MAY 21 2013
UPDATE...
DESPITE A MID LEVEL SHORTWAVE AND SUPPORT FROM THE LOW LEVEL
JET...MORNING CONVECTION HAS NOT HELD TOGETHER WELL AS IT HAS
TRAVELLED THROUGH SOUTHEAST MICHIGAN THIS MORNING. AS THE 06Z RUNS
COME IN THEY ARE KEEPING ADDITIONAL CONVECTION TO THE NORTH AND
SOUTH OF THE AREA WHERE THE BETTER DYNAMICS ARE...IN STARK
CONTRAST TO THE 00Z RUNS WHICH BLANKETED THE AREA WITH RAIN ALL
DAY. WATER VAPOR IMAGERY SHOWS SOME VALIDITY TO THIS THINKING AS
THE JET STREAM TO THE NORTH PULLS STORMS OVER THE NORTHERN GREAT
LAKES AND ACTIVITY TO THE SOUTH SHOWS SIGNS OF STAYING OVER THE
SOUTH. IT APPEARS SOUTHEAST MICHIGAN COULD BE IN BETWEEN ACTIVITY
TO THE NORTH AND SOUTH TODAY THE WAY WATER VAPOR IMAGERY IS
SHAPING UP. GIVEN THESE FACTORS WILL TONE DOWN POPS FROM
CATEGORICAL TO LIKELY...HOWEVER GOING BELOW THIS THRESHOLD WOULD
BE A MISTAKE WITH THE AMOUNT OF INSTABILITY THAT IS FORECAST TO
DEVELOP DURING THE AFTERNOON HOURS. FURTHER ADJUSTMENTS TO THE
FORECAST WILL BE MADE AS NECESSARY.
PREV DISCUSSION...ISSUED 342 AM EDT TUE MAY 21 2013
SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....MR
UPDATE.......MR
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 211413
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1013 AM EDT TUE MAY 21 2013
.UPDATE...
SE MICHIGAN REMAINS LODGED WITHIN A DEEP/MOIST AND PROGRESSIVELY
DESTABILIZING SOUTHWEST FLOW LATE THIS MORNING. SEVERAL HOUR WINDOW
OF NEARLY FULL INSOLATION CERTAINLY HELPING THIS PROCESS...ALTHOUGH
THE NORTHERN EXTENSION OF THE REMNANT CLOUD DEBRIS ATTACHED TO THE
LEFTOVER WEAK PV FILAMENT STREAMING INTO WEST-CENTRAL OHIO WILL
BEGIN TO FILTERING THE HEATING COMPONENT SLIGHTLY HEADING INTO
MIDDAY. HOWEVER GIVEN CURRENT TRENDS...HIGH TEMPERATURES OF LOWER
TO MIDDLE 80S CERTAINLY ARE ATTAINABLE. THIS PROJECTS TO ROUGHLY
1500 J/KG OF MLCAPE FOR THIS AFTERNOON.
DESPITE THIS EMERGING LOW LEVEL INSTABILITY GRADIENT...DELINEATING
BOTH THE LOCATION AND SCALE OF CONVECTIVE DEVELOPMENT...BOTH
UPSTREAM AND LOCALLY...REMAINS A CHALLENGE FOR THE AFTERNOON AND
EVENING PERIOD. 12Z DTX SOUNDING AND RECENT MODEL GUIDANCE SUGGEST
SOME DEGREE OF CAPPING REMAINS IN PLACE...ALBEIT NOT NEARLY AS
STRONG AS NOTED YESTERDAY. CONVECTIVE INITIATION MAY BECOME TIED TO
ADDITIONAL WEAK SHORTWAVE ENERGY AND ON THE LEAD EDGE OF AN
EXPANDING DIFFERENTIAL HEATING ZONE WORKING ACROSS MISSOURI AND INTO
SOUTHERN ILLINOIS. RECENT HI RES MODEL GUIDANCE PROVIDE FEW
CLUES...SUGGESTING A WINDOW FOR ISOLATED/SCATTERED DISCRETE CELL
DEVELOPMENT IN THAT FAVORED 19-22Z PERIOD. GIVEN A SOLID BACKGROUND
THERMODYNAMIC ENVIRONMENT TO MAINTAIN UPDRAFT STRENGTH...THE
PRESENCE OF A SUPPORTIVELY DEEP LAYER WIND FIELD WILL MAINTAIN A
RISK OF DAMAGING WINDS AND HAIL WITH ANY CELLS THAT CAN ORGANIZE
THROUGH THE PEAK HEATING CYCLE.
MINOR UPDATE ISSUED ALREADY TO READJUST POPS THROUGH THE EVENING AND
TWEAK TEMPERATURES BASED ON RECENT TRENDS.
&&
.AVIATION...ISSUED 727 AM EDT TUE MAY 21 2013
//DISCUSSION...
THE REGION OF THUNDERSTORMS THAT MOVED IN FROM ILLINOIS HAS HAD
LITTLE EFFECT OVER THE TAF SITES...AND WILL ONLY BRING SOME SHOWERS
TO KMBS EARLY THIS MORNING. THE EXTENT OF CLOUD COVER FROM THIS
COMPLEX WHICH MAY LINGER INTO THE AFTERNOON RAISES CONSIDERABLE
UNCERTAINTY WITH RESPECT TO THE CHANCES AND TIMING OF THUNDERSTORMS
LATER IN THE THIS AFTERNOON. BEST CHANCES FOR THUNDERSTORMS WILL BE
THIS AFTERNOON...THEREFORE WILL PUT A TEMPE GROUP IN THE 19-23Z TIME
FRAME WHEN THUNDERSTORMS ARE MOSTLY LIKELY TO OCCUR. A BREAK IN THE
ACTIVITY IS EXPECTED OVERNIGHT AS ONE OF THE SURFACE LOWS TRACKS
THROUGH THE NORTHERN GREAT LAKES.
FOR DTW...TIMING OF THUNDERSTORMS LATER IN THE DAY REMAINS HIGHLY
UNCERTAIN...THE BEST POTENTIAL WILL BE IN THE 19-23Z TIME FRAME WITH
MAX HEATING.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN THUNDERSTORMS THIS AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 738 AM EDT TUE MAY 21 2013
UPDATE...
DESPITE A MID LEVEL SHORTWAVE AND SUPPORT FROM THE LOW LEVEL
JET...MORNING CONVECTION HAS NOT HELD TOGETHER WELL AS IT HAS
TRAVELLED THROUGH SOUTHEAST MICHIGAN THIS MORNING. AS THE 06Z RUNS
COME IN THEY ARE KEEPING ADDITIONAL CONVECTION TO THE NORTH AND
SOUTH OF THE AREA WHERE THE BETTER DYNAMICS ARE...IN STARK
CONTRAST TO THE 00Z RUNS WHICH BLANKETED THE AREA WITH RAIN ALL
DAY. WATER VAPOR IMAGERY SHOWS SOME VALIDITY TO THIS THINKING AS
THE JET STREAM TO THE NORTH PULLS STORMS OVER THE NORTHERN GREAT
LAKES AND ACTIVITY TO THE SOUTH SHOWS SIGNS OF STAYING OVER THE
SOUTH. IT APPEARS SOUTHEAST MICHIGAN COULD BE IN BETWEEN ACTIVITY
TO THE NORTH AND SOUTH TODAY THE WAY WATER VAPOR IMAGERY IS
SHAPING UP. GIVEN THESE FACTORS WILL TONE DOWN POPS FROM
CATEGORICAL TO LIKELY...HOWEVER GOING BELOW THIS THRESHOLD WOULD
BE A MISTAKE WITH THE AMOUNT OF INSTABILITY THAT IS FORECAST TO
DEVELOP DURING THE AFTERNOON HOURS. FURTHER ADJUSTMENTS TO THE
FORECAST WILL BE MADE AS NECESSARY.
PREV DISCUSSION...ISSUED 342 AM EDT TUE MAY 21 2013
SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......MR
AVIATION.....KURIMSKI
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 211138
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
738 AM EDT TUE MAY 21 2013
.UPDATE...
DESPITE A MID LEVEL SHORTWAVE AND SUPPORT FROM THE LOW LEVEL
JET...MORNING CONVECTION HAS NOT HELD TOGETHER WELL AS IT HAS
TRAVELLED THROUGH SOUTHEAST MICHIGAN THIS MORNING. AS THE 06Z RUNS
COME IN THEY ARE KEEPING ADDITIONAL CONVECTION TO THE NORTH AND
SOUTH OF THE AREA WHERE THE BETTER DYNAMICS ARE...IN STARK
CONTRAST TO THE 00Z RUNS WHICH BLANKETED THE AREA WITH RAIN ALL
DAY. WATER VAPOR IMAGERY SHOWS SOME VALIDITY TO THIS THINKING AS
THE JET STREAM TO THE NORTH PULLS STORMS OVER THE NORTHERN GREAT
LAKES AND ACTIVITY TO THE SOUTH SHOWS SIGNS OF STAYING OVER THE
SOUTH. IT APPEARS SOUTHEAST MICHIGAN COULD BE IN BETWEEN ACTIVITY
TO THE NORTH AND SOUTH TODAY THE WAY WATER VAPOR IMAGERY IS
SHAPING UP. GIVEN THESE FACTORS WILL TONE DOWN POPS FROM
CATEGORICAL TO LIKELY...HOWEVER GOING BELOW THIS THRESHOLD WOULD
BE A MISTAKE WITH THE AMOUNT OF INSTABILITY THAT IS FORECAST TO
DEVELOP DURING THE AFTERNOON HOURS. FURTHER ADJUSTMENTS TO THE
FORECAST WILL BE MADE AS NECESSARY.
&&
.AVIATION...ISSUED 727 AM EDT TUE MAY 21 2013
//DISCUSSION...
THE REGION OF THUNDERSTORMS THAT MOVED IN FROM ILLINOIS HAS HAD
LITTLE EFFECT OVER THE TAF SITES...AND WILL ONLY BRING SOME SHOWERS
TO KMBS EARLY THIS MORNING. THE EXTENT OF CLOUD COVER FROM THIS
COMPLEX WHICH MAY LINGER INTO THE AFTERNOON RAISES CONSIDERABLE
UNCERTAINTY WITH RESPECT TO THE CHANCES AND TIMING OF THUNDERSTORMS
LATER IN THE THIS AFTERNOON. BEST CHANCES FOR THUNDERSTORMS WILL BE
THIS AFTERNOON...THEREFORE WILL PUT A TEMPE GROUP IN THE 19-23Z TIME
FRAME WHEN THUNDERSTORMS ARE MOSTLY LIKELY TO OCCUR. A BREAK IN THE
ACTIVITY IS EXPECTED OVERNIGHT AS ONE OF THE SURFACE LOWS TRACKS
THROUGH THE NORTHERN GREAT LAKES.
FOR DTW...TIMING OF THUNDERSTORMS LATER IN THE DAY REMAINS HIGHLY
UNCERTAIN...THE BEST POTENTIAL WILL BE IN THE 19-23Z TIME FRAME WITH
MAX HEATING.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN THUNDERSTORMS THIS AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 342 AM EDT TUE MAY 21 2013
SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......KURIMSKI
AVIATION.....KURIMSKI
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 211127
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
727 AM EDT TUE MAY 21 2013
.AVIATION...
//DISCUSSION...
THE REGION OF THUNDERSTORMS THAT MOVED IN FROM ILLINOIS HAS HAD
LITTLE EFFECT OVER THE TAF SITES...AND WILL ONLY BRING SOME SHOWERS
TO KMBS EARLY THIS MORNING. THE EXTENT OF CLOUD COVER FROM THIS
COMPLEX WHICH MAY LINGER INTO THE AFTERNOON RAISES CONSIDERABLE
UNCERTAINTY WITH RESPECT TO THE CHANCES AND TIMING OF THUNDERSTORMS
LATER IN THE THIS AFTERNOON. BEST CHANCES FOR THUNDERSTORMS WILL BE
THIS AFTERNOON...THEREFORE WILL PUT A TEMPE GROUP IN THE 19-23Z TIME
FRAME WHEN THUNDERSTORMS ARE MOSTLY LIKELY TO OCCUR. A BREAK IN THE
ACTIVITY IS EXPECTED OVERNIGHT AS ONE OF THE SURFACE LOWS TRACKS
THROUGH THE NORTHERN GREAT LAKES.
FOR DTW...TIMING OF THUNDERSTORMS LATER IN THE DAY REMAINS HIGHLY
UNCERTAIN...THE BEST POTENTIAL WILL BE IN THE 19-23Z TIME FRAME WITH
MAX HEATING.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN THUNDERSTORMS THIS AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 342 AM EDT TUE MAY 21 2013
SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....KURIMSKI
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 210742
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
342 AM EDT TUE MAY 21 2013
.SHORT TERM...TODAY AND TONIGHT
LINE OF THUNDERSTORMS CURRENTLY OVER NORTHERN ILLINOIS IS SLOWLY BUT
SURELY MARCHING NORTHEAST DURING THE EARLY MORNING HOURS. THE MAIN
QUESTION THIS MORNING IS HOW WELL THIS ACTIVITY WILL HOLD TOGETHER
AS IT TRACKS THROUGH SOUTHEAST MICHIGAN. HI-RES MODEL RUNS ARE IN
GENERAL AGREEMENT IN BRINGING THE SYSTEM THROUGH BETWEEN 09-13Z.
THAT IS WHERE THE AGREEMENT ENDS AS THE HRRR LIFTS THE BEST
THUNDERSTORM ACTIVITY NORTH THROUGH NORTHERN LOWER MICHIGAN WHILE
THE WRF MAINTAINS THE LINE OF STRONG THUNDERSTORMS AS IT TRACKS
THROUGH SOUTHEAST MICHIGAN...MAINLY NORTH OF THE M-59 CORRIDOR. THE
EVOLUTION OF THE JET STREAM WOULD VALIDATE THE HRRR SOLUTION AS IT
LIFTS THE 100+ KNOT JET NORTH OVER THE NORTHERN GREAT LAKES...TAKING
THE UPPER LEVEL DIVERGENCE AFFORDED BY THE RIGHT ENTRANCE REGION OF
THE JET WITH IT. HOWEVER LOWER LEVELS LEND CREDENCE TO THE WRF
SOLUTION AS THE MAIN SHORTWAVE DRIVING THE NORTHERN EDGE OF THE
CONVECTION IS PROGGED TO GO DIRECTLY THROUGH SOUTHEAST MICHIGAN WITH
THE NOSE OF THE 35 KNOT 850 MB LOW LEVEL JET POINTED OVER SOUTHEAST
MICHIGAN. DESPITE THE LOSS OF UPPER LEVEL JET SUPPORT...THE LOWER
LEVEL DYNAMICS POINT TO AN ACTIVE MORNING ACROSS SOUTHEAST MICHIGAN
WITH THE LINE OF CONVECTION EXPECTED TO SURVIVE THE TRIP AND TRACK
THROUGH THE AREA. THIS ACTIVITY WILL STILL HAVE QUITE A BIT OF
INSTABILITY TO WORK WITH AS MUCAPE VALUES REMAIN AT 1000 TO 1500
J/KG DURING THE EARLY MORNING HOURS. SEVERE WEATHER THREAT FROM THIS
MORNINGS CONVECTION WILL MAINLY BE A WIND THREAT...AS UPSTREAM
OBSERVATIONS SHOW LITTLE THREAT FROM LARGE HAIL...ALTHOUGH SMALL TO
NEAR SEVERE HAIL IS A POSSIBILITY.
AFTER THIS INITIAL ACTIVITY THE PICTURE BECOMES VERY MUDDLED AS THE
NWP MODELS KEEP SHOWERS AND THUNDERSTORMS GOING FOR MUCH OF THE DAY.
THIS SCENARIO IS CERTAINLY PLAUSIBLE AS ANOTHER JET STREAK LIFTS
FROM THE SOUTHWEST AND MAKES ITS WAY OVER THE GREAT LAKES REGION. AS
A RESULT THE AREA WILL BE IN THE PATH OF SEVERAL SHORTWAVES ROTATING
AROUND THE MAIN MID LEVEL LOW PRESSURE SYSTEM TAKING UP RESIDENCE
OVER THE MISSOURI VALLEY. WITHOUT A KEY FEATURE INDICATING THERE
WILL BE A SUBSTANTIAL BREAK FROM THE ACTION...DO NOT PLAN ON
DEVIATING MUCH FROM THE PREVIOUS FORECAST HIGH POPS THROUGH THE
DAYTIME HOURS.
SEVERE WEATHER POTENTIAL THIS AFTERNOON WILL HINGE ON THE ABILITY TO
GET A BREAK IN THE CONVECTION. THIS WINDOW WILL NOT HAVE TO BE
LARGE...AS EVIDENCED YESTERDAY...WITH A BRIEF BREAK ALLOWING
TEMPERATURES AND CAPES TO RISE SIGNIFICANTLY IN A SHORT PERIOD OF
TIME. MODELS SHOW MUCAPE VALUES RANGING FROM 500 TO 1000 J/KG WITH A
FAIRLY STEADY STREAM OF CONVECTION DURING THE DAY. AFTERNOON
SUNSHINE COULD EASILY BOOST THESE VALUES TO AROUND 1500 J/KG GIVEN
THE LATE MAY SUN ANGLE AND THE VERY WARM AIR IN THE LOW LEVELS. IN
ADDITION TO THE INSTABILITY...0-6 KM BULK SHEAR VALUES ARE A GOOD 30
TO 40 KNOTS TODAY...MEANING THE POTENTIAL FOR STRONG TO SEVERE
THUNDERSTORMS PRODUCING DAMAGING WINDS AND LARGE HAIL ARE A
POSSIBILITY. CLOSER INSPECTION OF THE HODOGRAPH AND LOW LEVEL CAPE
SHOW ISOLATED TORNADOES WILL ALSO BE A THREAT...ESPECIALLY IF WE CAN
GET SOME SUNSHINE...AS 0-3KM CAPE VALUES REACH 150 TO 200 J/KG AND
STORM RELATIVE HELICITY VALUES GET TO 150 TO 200 M2/S2. ALL OF THIS
ACTIVITY MAKES FORECASTING HIGH TEMPERATURES TODAY QUITE
CHALLENGING. EVEN WITH ALL OF THE ACTIVITY WE SHOULD BE ABLE TO GET
INTO THE LOW 80S AWAY FROM THE GREAT LAKES...HOWEVER A FEW MID 80S
ARE A DISTINCT POSSIBILITY IF THE AFOREMENTIONED BREAK IN THE
ACTIVITY OCCURS.
OVERNIGHT MODELS ARE HINTING AT A BREAK IN THE CONVECTION AS THE
SECONDARY JET STREAM MOVES OFF TO THE NORTH WITH NVA PROGGED AT THE
500 MB LEVEL AS THE SURFACE LOW LIFTS OVER THE SOO. EVEN WITH THESE
FACTORS THERE IS ABUNDANT LOW LEVEL MOISTURE ACROSS SOUTHEAST
MICHIGAN...SO A COMPLETELY DRY FORECAST IS NOT IN THE CARDS AND
NEITHER IS A CONTINUATION OF THE HIGH POPS FROM TODAY. WITH ALL
THESE FACTORS IN MIND WILL MAINTAIN CHANCY POPS DURING THE OVERNIGHT
HOURS. ABUNDANT CLOUD COVER AND THE REGION STILL IN THE WARM SECTOR
WILL ONCE AGAIN LEAD TO A MILD NIGHT WITH OVERNIGHT LOWS EXPECTED IN
THE 60S.
&&
.LONG TERM...WEDNESDAY THROUGH MONDAY
UPPER LEVEL TROUGHING WILL KEEP MENTION OF SHOWERS AND THUNDERSTORMS
AROUND INTO THURSDAY WHICH IS WHEN THE MAIN TROUGH AXIS PASSES EAST
OF THE AREA ALLOWING HEIGHTS TO BUILD. MEANWHILE...COMPLEX SFC LOW
PRESSURE SYSTEM WILL WORK THROUGH LOWER MI ON WEDNESDAY AND THURSDAY
BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM DROPS INTO THE GREAT
LAKES AND EXPANDS ACROSS MUCH OF THE EASTERN CONUS FOR THE HOLIDAY
WEEKEND. THIS WILL LEAD TO A DRY BUT COOL WEEKEND.
FIRST OFF WE WILL ADDRESS CONVECTIVE POTENTIAL FOR WEDNESDAY. THE
GFS POORLY INITIALIZES THE SFC LOW OVER THE NORTHERN PLAINS SO WILL
LEAN MORE TOWARD THE ECMWF/NAM/GEM REGIONAL. THE UPPER LEVEL LOW
THAT HAS BEEN SITTING OVER THE NORTHERN PLAINS FOR A FEW DAYS NOW
WILL PHASE WITH A NORTHERN STREAM TROUGH DIGGING SOUTH THROUGH
MANITOBA/ONTARIO ON WEDNESDAY. THIS WILL LEAD TO A MORE PROGRESSIVE
SYSTEM FINALLY. WITH THE CLOSED NATURE OF THE UPPER LOW...A FEW SFC
LOWS HAVE BEEN ROTATING AROUND EACH OTHER THE LAST TWO DAYS. AS THE
WAVE OPENS FURTHER AND THE UPPER JET TURNS WEST/EAST ACROSS NORTHERN
MI...THE MAIN SFC LOW WILL RELEASE AND TRACK ACROSS NORTHERN LOWER
MI THROUGH THE DAY WEDNESDAY. THIS WILL BE A BROAD WEAKENING LOW BUT
WILL PRESENT ISENTROPIC ASCENT AND WILL KEEP THE THETA E RIDGE UP
INTO SE MI. FOCUS WILL BE PLACED ON A SOUTHERN STREAM SHORTWAVE THAT
WILL ROUND THE BASE OF THE TROUGH AND TARGET LOWER MI WEDNESDAY
AFTERNOON. MODEL CONSENSUS SHOWS A SFC LOW CLIPPING EXTREME SE MI.
THIS WILL OPEN THE DOOR FOR ADDITIONAL HEATING AND MOISTURE INTO
THAT AREA DURING PEAK AFTERNOON HEATING WITH THE EASTWARD TRACKING
UPPER LEVEL JET MORE SQUARELY OVERHEAD. CONVECTIVE PARAMETERS ARE ON
THE DECLINE FROM MONDAY AND TUESDAY BUT THERE WILL STILL BE 500 TO
1000 J/KG OF TALL SKINNY MUCAPE WITH A COLD/COOL FRONT PASSING
THROUGH THE AREA IN THE EVENING. OVERALL WEDNESDAY LOOKS LIKE IT
WILL BE COMPOSED OF WIDESPREAD SHOWERS AND THUNDERSTORMS WITH A
CHANCE OF ORGANIZED CONVECTION ACROSS THE EXTREME SE PORTION OF THE
CWA.
UPPER LEVEL TROUGH AXIS WILL BE OVER WESTERN LOWER MI WEDNESDAY
NIGHT PROVIDING BROAD AREA OF LIFT ALOFT WITH THE BACK END OF THE
SFC LOW STILL LINGERING. THIS WILL KEEP SHOWERS AND THUNDERSTORMS
OVER MUCH OF LOWER MI THROUGH THE OVERNIGHT. THE AXIS WILL SWEEP
THROUGH SE MI EARLY ON THURSDAY LEADING TO A CLEARING TREND IN THE
SHOWERS THROUGH THE DAY FROM NW TO SE. MAIN BAROCLINIC ZONE THATS
BEEN LINGERING ACROSS THE NORTHERN GREAT LAKES WILL SURGE SOUTH ON
THURSDAY WITH STRONG CANADIAN HIGH PRESSURE RIGHT BEHIND IT. WITH
BUILDING HEIGHTS ALOFT...CLOUDS WILL CLEAR OUT BUT THAT WILL NOT BE
REALIZED IN TEMPERATURES. 850 MB TEMPS IN THE LOW SINGLE DIGITS WILL
ONLY ALLOW HIGH TEMPS TO REACH AROUND 60F BOTH THURSDAY AND FRIDAY
WITH LOWS AROUND 40. A SLOW WARMING TREND THROUGH THE WEEKEND WILL
ONLY ALLOW TEMPS TO REBOUND TO NEAR 70 FOR MONDAY AND TUESDAY.
THOUGH IT WILL BE COOL...AT LEAST IT LOOKS TO STAY DRY THOUGHT THE
HOLIDAY WEEKEND.
&&
.MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE TODAY AND WEDNESDAY AS A
LOW PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A
WARM AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
DURING THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST. THESE CONDITIONS WILL PUSH WINDS AND WAVES CLOSE TO SMALL
CRAFT CRITERIA ON THURSDAY OVER LAKE HURON.
&&
.AVIATION...ISSUED 1151 PM EDT MON MAY 20 2013
//DISCUSSION...
THE REGION OF THUNDERSTORMS ACROSS ILLINOIS WILL LIFT N-NE DURING
THE EARLY MORNING HOURS. ADDITIONAL CONVECTIVE DEVELOPMENT IS
POSSIBLE OUT AHEAD OF THIS CLUSTER WITHIN A SECONDARY SURGE IN
MOISTURE...TRAVERSING SE MI IN THE 09Z TO 15Z TIME FRAME. THIS WILL
SUPPORT THE INCLUSION OF SOME THUNDERSTORMS IN THE TAFS AROUND
DAYBREAK. THE COVERAGE OF MORNING CONVECTIVE ACTIVITY AND EXTENT OF
CLOUD COVER WHICH MAY LINGER INTO THE AFTERNOON RAISES CONSIDERABLE
UNCERTAINTY WITH RESPECT TO THE CHANCES AND TIMING OF THUNDERSTORMS
LATER IN THE DAY TUESDAY.
FOR DTW...GIVEN THE EASTWARD EXTENT OF CONVECTION ONGOING ACROSS
ILLINOIS...CHANCES OF SOME THUNDERSTORM ACTIVITY IN AND AROUND METRO
APPEAR HIGH ENOUGH TO ADD THEIR INCLUSION IN THE TAFS DURING THE 11
TO 14Z TIME FRAME. ALTHOUGH TIMING OF ADDITIONAL THUNDERSTORMS LATER
IN THE DAY TUESDAY REMAINS HIGHLY UNCERTAIN...THERE IS THE POTENTIAL
FOR SEVERAL ROUNDS OF THUNDERSTORMS TO IMPACT METRO ON TUESDAY.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN THUNDERSTORMS TUESDAY MORNING AND AFTERNOON.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
AVIATION.....SC
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 210351
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1151 PM EDT MON MAY 20 2013
.AVIATION...
//DISCUSSION...
THE REGION OF THUNDERSTORMS ACROSS ILLINOIS WILL LIFT N-NE DURING
THE EARLY MORNING HOURS. ADDITIONAL CONVECTIVE DEVELOPMENT IS
POSSIBLE OUT AHEAD OF THIS CLUSTER WITHIN A SECONDARY SURGE IN
MOISTURE...TRAVERSING SE MI IN THE 09Z TO 15Z TIME FRAME. THIS WILL
SUPPORT THE INCLUSION OF SOME THUNDERSTORMS IN THE TAFS AROUND
DAYBREAK. THE COVERAGE OF MORNING CONVECTIVE ACTIVITY AND EXTENT OF
CLOUD COVER WHICH MAY LINGER INTO THE AFTERNOON RAISES CONSIDERABLE
UNCERTAINTY WITH RESPECT TO THE CHANCES AND TIMING OF THUNDERSTORMS
LATER IN THE DAY TUESDAY.
FOR DTW...GIVEN THE EASTWARD EXTENT OF CONVECTION ONGOING ACROSS
ILLINOIS...CHANCES OF SOME THUNDERSTORM ACTIVITY IN AND AROUND METRO
APPEAR HIGH ENOUGH TO ADD THEIR INCLUSION IN THE TAFS DURING THE 11
TO 14Z TIME FRAME. ALTHOUGH TIMING OF ADDITIONAL THUNDERSTORMS LATER
IN THE DAY TUESDAY REMAINS HIGHLY UNCERTAIN...THERE IS THE POTENTIAL
FOR SEVERAL ROUNDS OF THUNDERSTORMS TO IMPACT METRO ON TUESDAY.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN THUNDERSTORMS TUESDAY MORNING AND AFTERNOON.
&&
.PREV DISCUSSION...ISSUED 1030 PM EDT MON MAY 20 2013
UPDATE...
SE MI WILL BE IN A LULL IN CONVECTIVE ACTIVITY FOR THE NEXT
SEVERAL HOURS AS SUBSIDENCE HAS OVERSPREAD THE AREA IN THE WAKE OF
THE EARLIER CONVECTION WHICH IMPACTED THE NORTHERN HALF OF THE
FORECAST AREA. ATTENTION NOW TURNS TO THE CONVECTIVE COMPLEX OVER
NORTH CENTRAL ILLINOIS. THESE STORMS WILL CONTINUE TO MOVE
N-NE IN ADVANCE OF MID LEVEL IMPULSE. THIS MID LEVEL SHORT WAVE
WILL LIFT INTO WISCONSIN/LAKE MI OVERNIGHT. INCREASED LOW LEVEL
MOISTURE ADVECTION UNDER STRENGTHENING LOW LEVEL INFLOW AND
FAVORABLE UPPER JET DYNAMICS WILL SUPPORT ADDITIONAL CONVECTIVE
DEVELOPMENT INTO SW LOWER MI OVERNIGHT...EVENTUALLY INTO SE MI
TOWARD DAYBREAK TUES. THE ZONES/GRIDS HAVE ALREADY BEEN UPDATED TO
REFLECT THIS. STEEP MID LEVEL LAPSE RATES AND SLIGHTLY STRONGER
DEEP LAYER SHEAR /IN COMPARISON TO TODAY/ WILL SUPPORT A SLIGHT
RISK OF SEVERE STORMS LATE TONIGHT INTO THE DAY TUESDAY.
PREV DISCUSSION...ISSUED 401 PM EDT MON MAY 20 2013
SHORT TERM...TODAY AND TONIGHT
WARM SECTOR AIRMASS FIRMLY ENTRENCHED ACROSS SE MICHIGAN THIS
AFTERNOON. LATEST OBSERVATIONS SHOWING TEMPERATURES MAKING A RUN TO
NEAR 90 DEGREES IN SOME LOCATIONS. DEEPER PLUME OF LOW LEVEL
MOISTURE BANKED ALONG THE INTERFACE OF THE UPPER RIDGE AXIS HOLDING
JUST TO THE EAST AND THE EXTENSIVE CLOSED LOW CIRCULATING OVER THE
DAKOTAS NOW EXTENDING THROUGHOUT LOWER MICHIGAN. THIS COMBINATION
TRANSLATING INTO A SOLID INSTABILITY AXIS...RECENT SPC MESOANALYSIS
INDICATING MLCAPE VALUES IN EXCESS 2000 J/KG. DESPITE THIS...
SOUTHEAST MICHIGAN STILL FEELING THE IMPACT OF THE NEARBY HIGHER
HEIGHT FIELD...AS NOTED BY THE 18Z DTX SOUNDING WHICH SHOWS A FAIRLY
STOUT 900-800 MB CAPPING INVERSION. THIS EFFECTIVELY CONTAINS THE
CONVECTIVE TEMPERATURE AT 90 DEGREE OR WARMER...LEAVING THE
PROSPECTS FOR SEEING CONVECTION CONDITIONALLY DEPENDENT ON REALIZING
SOME DEGREE OF FORCED ASCENT AND/OR CONSOLIDATING CONVECTIVELY
GENERATED COLD POOL DYNAMICS.
LINEAR EXPANSION OF CONVECTION UNDERWAY TO THE WEST/NORTHWEST
SUSTAINED BY A COMBINATION OF A PASSING MID LEVEL IMPULSE AND SOME
TYPE OF LAKE MICHIGAN MARINE INFLUENCE/BOUNDARY. THE POTENTIAL
REMAINS FOR SOME FORM OF EAST/NORTHEASTWARD EXPANSION OF THIS
ACTIVITY ALONG A FAVORABLY ALIGNED CORFIDI VECTOR AND INTO THE
INSTABILITY BUBBLE RESIDING OVER SE MICHIGAN. 12Z HI RES MODEL
SOLUTIONS CONTINUE TO POINT IN THIS DIRECTION. HOWEVER RELATIVELY
MODEST DEEP LAYER SHEAR EAST OF THIS LINE DOES LEAVE SOME QUESTION
AS TO THE ORGANIZATIONAL CAPACITY AND POTENTIAL COVERAGE OF ANY
INBOUND CONVECTION. NONETHELESS...GIVEN THE DEGREE OF INSTABILITY
IN PLACE...CONDITIONAL SEVERE THUNDERSTORM RISK CERTAINLY
EXISTS...ESPECIALLY ACROSS NORTHERN SECTIONS OF THE FORECAST AREA.
SEVERE THUNDERSTORM WATCH IS IN PLACE THROUGH 8 PM FROM WASHTENAW/
WAYNE COUNTIES NORTHWARD.
DECAYING CONVECTIVE COMPLEX LOCKED ONTO THE NEXT IN A SERIES OF WEAK
IMPULSES EJECTING AROUND THE UPPER MIDWEST LOW CONTINUES TO SHIFT
THROUGH NORTHERN ILLINOIS. A CONSIDERABLY LESS SUPPORTIVE
THERMODYNAMIC ENVIRONMENT ACROSS THAT CORRIDOR /DEWPOINTS IN THE
50S/ LEADING TO THIS WEAKENING TREND...BUT SOME POTENTIAL DOES EXIST
FOR RENEWED DEVELOPMENT AND UPSCALE GROWTH THROUGH THE LATTER HALF
OF THE EVENING AS THIS WAVE ENCOUNTERS THE BETTER INSTABILITY/
MOISTURE AXIS. THIS WILL CONTINUE TO SUPPORT A CHANCE POP MENTION.
THE OVERNIGHT/EARLY MORNING PERIOD BECOMES MORE MUDDLED...DEPENDENCE
ON PROPERLY DEFINING THE TRAJECTORY OF ADDITIONAL ILL-DEFINED
SHORTWAVE ENERGY AND/OR CONVECTIVE DEBRIS. EMERGING NOCTURNAL LOW
LEVEL JET FORCING AND SUSTAINABLE HIGHER LAPSE RATES LEND MORE
CONFIDENCE THAT SOME FORM OF ADDITIONAL CONVECTION WILL TAKE AIM ON
THE REGION LATE TONIGHT...BUT DEFINING THE DETAILS OF
LOCATION/TIMING AND COVERAGE REMAINS A CHALLENGE. A MILD NIGHT
AHEAD GIVEN THE ELEVATED DEWPOINTS...LOWS MID TO UPPER 60S.
LONG TERM...TUESDAY THROUGH SUNDAY
THE MAIN DRIVER OF THE WEATHER TUESDAY WILL BE THE MOMENTUM TRANSFER
THAT WILL OCCUR OF UPPER LEVEL JET ENERGY OVER THE RIDGE AXIS.
ORIENTATION OF UPPER LEVEL RIDGING OVER NORTHERN GREAT LAKES AND
ONTARIO WILL THEN CHANGE FROM CYCLONIC TO ANTICYCLONIC CURVATURE.
FUNDAMENTALLY...THIS WILL PUT SOUTHEASTERN MICHIGAN IN A DIFFERENT
REGIME AS THE AREA WILL BECOME IN CLOSER PROXIMITY TO THE UPPER
LEVEL JET AXIS. PROXIMITY TO THE UPPER LEVEL JET AXIS IS NEVER A
TRIVIAL QUESTION...BECAUSE A CLOSER PROXIMITY MEANS ONE IS CLOSER TO
THE FIREHOSE OR PATH OF EMBEDDED SHORTWAVE ENERGY. HOWEVER...WHAT IS
A MORE DIFFICULT DETERMINATION IS THE OVERALL CRISPNESS OR EDGE
QUALITY TO THE UPPER LEVEL RIDGE. IN OTHER WORDS...A GREATER
POTENTIAL WILL EXIST FOR PERIODIC SHOWERS AND THUNDERSTORMS
THROUGHOUT TUESDAY AND TUESDAY NIGHT.
THE SEVERE WEATHER THREAT FOR TUESDAY WILL BE PARTIALLY INFLUENCED
BY AREAL COVERAGE AND DURATION OF ONGOING THUNDERSTORMS DURING THE
PRE-NOON TIMEFRAME. HOWEVER...GIVEN LATE MAY NUMBER OF DAYLIGHT
HOURS AND SOLAR INTENSITY...ANY BREAK IN CLOUD COVER WILL ALLOW
SURFACE TEMPERATURES TO CLIMB AND CAPES TO BUILD. THERE IS SURELY
CONTAMINATION OF THE THERMODYNAMIC ENVIRONMENT IN THE MODELS BUT
CONFIDENCE IS HIGH THAT 700-500 MB LAPSE RATES WILL NOT BE ANYWHERE
NEAR AS PRISTINE. LIKELY NOT MOIST ADIABATIC BUT CERTAINLY NOT 7.5-8
DEG C/KM EITHER. SBCAPES ARE EXPECTED TO REACH 1000 J/KG WITH
MLCAPES LIKELY STRUGGLING TO REACH THAT SAME THRESHOLD. CLOSER
PROXIMITY TO JET WILL BRING SOLID 30-40 KNOTS OF 0-6KM BULK
SHEAR....GOOD FOR A POTENTIAL OF STRONG TO POSSIBLY SEVERE
THUNDERSTORMS FOR DAMAGING WIND GUSTS AND LARGE HAIL.
A CONVECTIVELY MODULATED BOUNDARY LAYER AND HIGHER SPEED FLOW
OVERHEAD MAKES THE TIMING OF INDIVIDUAL FORCING ELEMENTS DIFFICULT.
WILL OFFER A THOUGHT OR TWO TO THINK ABOUT DESPITE THE NOISE. SOME
MODEL DATA SUGGESTS THAT DIFFERENTIAL AIRMASS RECOVERY MAY OCCUR
PRIMARILY FROM THE IRISH HILLS TO THE SOUTHEAST. A PERTURBATION TO
THE FLOW OR RIBBON OF ENHANCED CONVERGENCE IS HIGHLIGHTED ON SOME
REMNANT CONVECTIVE SHORTWAVE ENERGY IS HIGHLIGHTED TO TRACK THROUGH
TOMORROW IN SOUTHWEST FLOW. BEST IDEA ON TIMING FOR STRONG TO
SEVERE STORMS IS 19-23Z. ALL OF SOUTHEASTERN MICHIGAN IS IN THE
SLIGHT RISK ON SWODY2.
CONVECTION THAT DEVELOPS DURING THE DAY ON TUESDAY WILL BEGIN TO
DIMINISH BY EVENING. A LULL IN THE THUNDERSTORMS DEVELOP FOR THE
OVERNIGHT PERIOD AS ONE LOW PRESSURE SYSTEM MOVES OFF INTO CANADA
AND ANOTHER SECONDARY LOW DEEPENS OVER IOWA AND NORTHERN ILLINOIS.
HOWEVER...CURRENT MODEL SOUNDINGS ARE INDICATING MORE LOW LEVEL
MOISTURE IN BETWEEN THESE TWO LOW PRESSURE SYSTEMS THAN PREVIOUS
RUNS SO HAVE INCREASED THE FORECAST TO HIGH CHANCE POPS TO ACCOUNT
FOR ANY SHOWERS THAT WILL CONTINUE THROUGH THE OVERNIGHT PERIOD.
CURRENT MODEL RUNS ARE FAIRLY WELL IN AGREEMENT WITH ONE ANOTHER
BRINGING THE CENTER OF THE SURFACE LOW WILL ACROSS CENTRAL MICHIGAN
ON WEDNESDAY AS THE UPPER LOW MERGES INTO THE FLOW OVER CANADA. THIS
WILL BRING A CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH
THE DAY. AS THE COLD FRONT FINALLY MOVES OVER SOUTHERN MICHIGAN ON
WEDNESDAY NIGHT...RAIN WILL CONTINUE THROUGH WEDNESDAY NIGHT. THE
BACK END OF THIS LOW WILL LACK ANY SUPPORT FOR ORGANIZED CONVECTION
ON THURSDAY WITH ONLY RAIN CONTINUING FOR MOST OF THE DAY ON
THURSDAY. COLDER AIR BEGINS TO FILTER IN BEHIND THE PASSING LOW ON
THURSDAY RESULTING IN HIGH TEMPERATURES TO ONLY BE IN THE UPPER 50S TO
LOW 60S ACROSS THE CWA.
A FEW LINGERING RAIN SHOWERS WILL PERSIST INTO THE THURSDAY NIGHT
TIME FRAME BEFORE AN UPPER LEVEL RIDGE BUILDS INTO THE CENTRAL
PLAINS. THIS WILL KEEP SURFACE HIGH PRESSURE OVER THE REGION THROUGH
THE WEEKEND RESULTING IN DRY CONDITIONS. THIS HIGH WILL ALSO
CONTINUE TO USHER IN MUCH COOLER TEMPERATURES WITH HIGHS ON FRIDAY
ONLY IN THE LOW TO MID 60S AND SLOWLY INCREASING TO THE UPPER 60S BY
SUNDAY. LOW TEMPERATURES WILL DIP DOWN INTO THE UPPER 30S AND LOW
40S OVER THE WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE THROUGH MIDWEEK AS A LOW
PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A WARM
AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
THROUGH THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....SC
UPDATE.......SC
SHORT TERM...MR
LONG TERM....RK/CB
MARINE.......MR
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 210230
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1030 PM EDT MON MAY 20 2013
.UPDATE...
SE MI WILL BE IN A LULL IN CONVECTIVE ACTIVITY FOR THE NEXT
SEVERAL HOURS AS SUBSIDENCE HAS OVERSPREAD THE AREA IN THE WAKE OF
THE EARLIER CONVECTION WHICH IMPACTED THE NORTHERN HALF OF THE
FORECAST AREA. ATTENTION NOW TURNS TO THE CONVECTIVE COMPLEX OVER
NORTH CENTRAL ILLINOIS. THESE STORMS WILL CONTINUE TO MOVE
N-NE IN ADVANCE OF MID LEVEL IMPULSE. THIS MID LEVEL SHORT WAVE
WILL LIFT INTO WISCONSIN/LAKE MI OVERNIGHT. INCREASED LOW LEVEL
MOISTURE ADVECTION UNDER STRENGTHENING LOW LEVEL INFLOW AND
FAVORABLE UPPER JET DYNAMICS WILL SUPPORT ADDITIONAL CONVECTIVE
DEVELOPMENT INTO SW LOWER MI OVERNIGHT...EVENTUALLY INTO SE MI
TOWARD DAYBREAK TUES. THE ZONES/GRIDS HAVE ALREADY BEEN UPDATED TO
REFLECT THIS. STEEP MID LEVEL LAPSE RATES AND SLIGHTLY STRONGER
DEEP LAYER SHEAR /IN COMPARISON TO TODAY/ WILL SUPPORT A SLIGHT
RISK OF SEVERE STORMS LATE TONIGHT INTO THE DAY TUESDAY.
&&
.AVIATION...ISSUED 643 PM EDT MON MAY 20 2013
//DISCUSSION...
ONGOING LINE OF THUNDERSTORMS AT THE START OF THE TAF PERIOD WILL
CONTINUE TO LIFT OFF TO THE NORTHEAST THIS EVENING. SUBSIDENCE IN
THE WAKE OF THIS INITIAL CONVECTIVE LINE SHOULD INHIBIT ADDITIONAL
CONVECTION THROUGH AT LEAST 06 TO 08Z. LOW LEVEL MOISTURE RETURN
LATE TONIGHT AND BUILDING INSTABILITY THROUGH THE DAY ON TUESDAY
WILL LEAD TO ADDITIONAL THUNDERSTORM DEVELOPMENT. TIMING AT THIS
STAGE IS VERY UNCERTAIN. WHILE THERE MAY BE SOME EARLY MORNING
THUNDERSTORM ACTIVITY...THUNDERSTORMS WILL BE CONFINED TO THE PEAK
IN THE DIURNAL HEATING CYCLE IN THE TAFS AT THIS TIME.
FOR DTW...THE POTENTIAL FOR THUNDERSTORMS IMPACTING METRO THIS
EVENING IS GROWING MORE UNCERTAIN AS THE MAIN LINE OF STORMS HAS
BEEN LIFTING OFF TO THE NE. GIVEN THE POOL OF INSTABILITY OVER METRO
DETROIT...SOME ADDITIONAL DEVELOPMENT OFF THE SOUTHERN END OF THE
CONVECTIVE LINE MAY YET OCCUR. ANY DEVELOPMENT WOULD MOST LIKELY
IMPACT METRO BETWEEN 00Z AND 03Z.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE IN THUNDERSTORM DEVELOPMENT THIS EVENING AND
MEDIUM CONFIDENCE ON TUESDAY.
&&
.PREV DISCUSSION...ISSUED 401 PM EDT MON MAY 20 2013
SHORT TERM...TODAY AND TONIGHT
WARM SECTOR AIRMASS FIRMLY ENTRENCHED ACROSS SE MICHIGAN THIS
AFTERNOON. LATEST OBSERVATIONS SHOWING TEMPERATURES MAKING A RUN TO
NEAR 90 DEGREES IN SOME LOCATIONS. DEEPER PLUME OF LOW LEVEL
MOISTURE BANKED ALONG THE INTERFACE OF THE UPPER RIDGE AXIS HOLDING
JUST TO THE EAST AND THE EXTENSIVE CLOSED LOW CIRCULATING OVER THE
DAKOTAS NOW EXTENDING THROUGHOUT LOWER MICHIGAN. THIS COMBINATION
TRANSLATING INTO A SOLID INSTABILITY AXIS...RECENT SPC MESOANALYSIS
INDICATING MLCAPE VALUES IN EXCESS 2000 J/KG. DESPITE THIS...
SOUTHEAST MICHIGAN STILL FEELING THE IMPACT OF THE NEARBY HIGHER
HEIGHT FIELD...AS NOTED BY THE 18Z DTX SOUNDING WHICH SHOWS A FAIRLY
STOUT 900-800 MB CAPPING INVERSION. THIS EFFECTIVELY CONTAINS THE
CONVECTIVE TEMPERATURE AT 90 DEGREE OR WARMER...LEAVING THE
PROSPECTS FOR SEEING CONVECTION CONDITIONALLY DEPENDENT ON REALIZING
SOME DEGREE OF FORCED ASCENT AND/OR CONSOLIDATING CONVECTIVELY
GENERATED COLD POOL DYNAMICS.
LINEAR EXPANSION OF CONVECTION UNDERWAY TO THE WEST/NORTHWEST
SUSTAINED BY A COMBINATION OF A PASSING MID LEVEL IMPULSE AND SOME
TYPE OF LAKE MICHIGAN MARINE INFLUENCE/BOUNDARY. THE POTENTIAL
REMAINS FOR SOME FORM OF EAST/NORTHEASTWARD EXPANSION OF THIS
ACTIVITY ALONG A FAVORABLY ALIGNED CORFIDI VECTOR AND INTO THE
INSTABILITY BUBBLE RESIDING OVER SE MICHIGAN. 12Z HI RES MODEL
SOLUTIONS CONTINUE TO POINT IN THIS DIRECTION. HOWEVER RELATIVELY
MODEST DEEP LAYER SHEAR EAST OF THIS LINE DOES LEAVE SOME QUESTION
AS TO THE ORGANIZATIONAL CAPACITY AND POTENTIAL COVERAGE OF ANY
INBOUND CONVECTION. NONETHELESS...GIVEN THE DEGREE OF INSTABILITY
IN PLACE...CONDITIONAL SEVERE THUNDERSTORM RISK CERTAINLY
EXISTS...ESPECIALLY ACROSS NORTHERN SECTIONS OF THE FORECAST AREA.
SEVERE THUNDERSTORM WATCH IS IN PLACE THROUGH 8 PM FROM WASHTENAW/
WAYNE COUNTIES NORTHWARD.
DECAYING CONVECTIVE COMPLEX LOCKED ONTO THE NEXT IN A SERIES OF WEAK
IMPULSES EJECTING AROUND THE UPPER MIDWEST LOW CONTINUES TO SHIFT
THROUGH NORTHERN ILLINOIS. A CONSIDERABLY LESS SUPPORTIVE
THERMODYNAMIC ENVIRONMENT ACROSS THAT CORRIDOR /DEWPOINTS IN THE
50S/ LEADING TO THIS WEAKENING TREND...BUT SOME POTENTIAL DOES EXIST
FOR RENEWED DEVELOPMENT AND UPSCALE GROWTH THROUGH THE LATTER HALF
OF THE EVENING AS THIS WAVE ENCOUNTERS THE BETTER INSTABILITY/
MOISTURE AXIS. THIS WILL CONTINUE TO SUPPORT A CHANCE POP MENTION.
THE OVERNIGHT/EARLY MORNING PERIOD BECOMES MORE MUDDLED...DEPENDENCE
ON PROPERLY DEFINING THE TRAJECTORY OF ADDITIONAL ILL-DEFINED
SHORTWAVE ENERGY AND/OR CONVECTIVE DEBRIS. EMERGING NOCTURNAL LOW
LEVEL JET FORCING AND SUSTAINABLE HIGHER LAPSE RATES LEND MORE
CONFIDENCE THAT SOME FORM OF ADDITIONAL CONVECTION WILL TAKE AIM ON
THE REGION LATE TONIGHT...BUT DEFINING THE DETAILS OF
LOCATION/TIMING AND COVERAGE REMAINS A CHALLENGE. A MILD NIGHT
AHEAD GIVEN THE ELEVATED DEWPOINTS...LOWS MID TO UPPER 60S.
LONG TERM...TUESDAY THROUGH SUNDAY
THE MAIN DRIVER OF THE WEATHER TUESDAY WILL BE THE MOMENTUM TRANSFER
THAT WILL OCCUR OF UPPER LEVEL JET ENERGY OVER THE RIDGE AXIS.
ORIENTATION OF UPPER LEVEL RIDGING OVER NORTHERN GREAT LAKES AND
ONTARIO WILL THEN CHANGE FROM CYCLONIC TO ANTICYCLONIC CURVATURE.
FUNDAMENTALLY...THIS WILL PUT SOUTHEASTERN MICHIGAN IN A DIFFERENT
REGIME AS THE AREA WILL BECOME IN CLOSER PROXIMITY TO THE UPPER
LEVEL JET AXIS. PROXIMITY TO THE UPPER LEVEL JET AXIS IS NEVER A
TRIVIAL QUESTION...BECAUSE A CLOSER PROXIMITY MEANS ONE IS CLOSER TO
THE FIREHOSE OR PATH OF EMBEDDED SHORTWAVE ENERGY. HOWEVER...WHAT IS
A MORE DIFFICULT DETERMINATION IS THE OVERALL CRISPNESS OR EDGE
QUALITY TO THE UPPER LEVEL RIDGE. IN OTHER WORDS...A GREATER
POTENTIAL WILL EXIST FOR PERIODIC SHOWERS AND THUNDERSTORMS
THROUGHOUT TUESDAY AND TUESDAY NIGHT.
THE SEVERE WEATHER THREAT FOR TUESDAY WILL BE PARTIALLY INFLUENCED
BY AREAL COVERAGE AND DURATION OF ONGOING THUNDERSTORMS DURING THE
PRE-NOON TIMEFRAME. HOWEVER...GIVEN LATE MAY NUMBER OF DAYLIGHT
HOURS AND SOLAR INTENSITY...ANY BREAK IN CLOUD COVER WILL ALLOW
SURFACE TEMPERATURES TO CLIMB AND CAPES TO BUILD. THERE IS SURELY
CONTAMINATION OF THE THERMODYNAMIC ENVIRONMENT IN THE MODELS BUT
CONFIDENCE IS HIGH THAT 700-500 MB LAPSE RATES WILL NOT BE ANYWHERE
NEAR AS PRISTINE. LIKELY NOT MOIST ADIABATIC BUT CERTAINLY NOT 7.5-8
DEG C/KM EITHER. SBCAPES ARE EXPECTED TO REACH 1000 J/KG WITH
MLCAPES LIKELY STRUGGLING TO REACH THAT SAME THRESHOLD. CLOSER
PROXIMITY TO JET WILL BRING SOLID 30-40 KNOTS OF 0-6KM BULK
SHEAR....GOOD FOR A POTENTIAL OF STRONG TO POSSIBLY SEVERE
THUNDERSTORMS FOR DAMAGING WIND GUSTS AND LARGE HAIL.
A CONVECTIVELY MODULATED BOUNDARY LAYER AND HIGHER SPEED FLOW
OVERHEAD MAKES THE TIMING OF INDIVIDUAL FORCING ELEMENTS DIFFICULT.
WILL OFFER A THOUGHT OR TWO TO THINK ABOUT DESPITE THE NOISE. SOME
MODEL DATA SUGGESTS THAT DIFFERENTIAL AIRMASS RECOVERY MAY OCCUR
PRIMARILY FROM THE IRISH HILLS TO THE SOUTHEAST. A PERTURBATION TO
THE FLOW OR RIBBON OF ENHANCED CONVERGENCE IS HIGHLIGHTED ON SOME
REMNANT CONVECTIVE SHORTWAVE ENERGY IS HIGHLIGHTED TO TRACK THROUGH
TOMORROW IN SOUTHWEST FLOW. BEST IDEA ON TIMING FOR STRONG TO
SEVERE STORMS IS 19-23Z. ALL OF SOUTHEASTERN MICHIGAN IS IN THE
SLIGHT RISK ON SWODY2.
CONVECTION THAT DEVELOPS DURING THE DAY ON TUESDAY WILL BEGIN TO
DIMINISH BY EVENING. A LULL IN THE THUNDERSTORMS DEVELOP FOR THE
OVERNIGHT PERIOD AS ONE LOW PRESSURE SYSTEM MOVES OFF INTO CANADA
AND ANOTHER SECONDARY LOW DEEPENS OVER IOWA AND NORTHERN ILLINOIS.
HOWEVER...CURRENT MODEL SOUNDINGS ARE INDICATING MORE LOW LEVEL
MOISTURE IN BETWEEN THESE TWO LOW PRESSURE SYSTEMS THAN PREVIOUS
RUNS SO HAVE INCREASED THE FORECAST TO HIGH CHANCE POPS TO ACCOUNT
FOR ANY SHOWERS THAT WILL CONTINUE THROUGH THE OVERNIGHT PERIOD.
CURRENT MODEL RUNS ARE FAIRLY WELL IN AGREEMENT WITH ONE ANOTHER
BRINGING THE CENTER OF THE SURFACE LOW WILL ACROSS CENTRAL MICHIGAN
ON WEDNESDAY AS THE UPPER LOW MERGES INTO THE FLOW OVER CANADA. THIS
WILL BRING A CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH
THE DAY. AS THE COLD FRONT FINALLY MOVES OVER SOUTHERN MICHIGAN ON
WEDNESDAY NIGHT...RAIN WILL CONTINUE THROUGH WEDNESDAY NIGHT. THE
BACK END OF THIS LOW WILL LACK ANY SUPPORT FOR ORGANIZED CONVECTION
ON THURSDAY WITH ONLY RAIN CONTINUING FOR MOST OF THE DAY ON
THURSDAY. COLDER AIR BEGINS TO FILTER IN BEHIND THE PASSING LOW ON
THURSDAY RESULTING IN HIGH TEMPERATURES TO ONLY BE IN THE UPPER 50S TO
LOW 60S ACROSS THE CWA.
A FEW LINGERING RAIN SHOWERS WILL PERSIST INTO THE THURSDAY NIGHT
TIME FRAME BEFORE AN UPPER LEVEL RIDGE BUILDS INTO THE CENTRAL
PLAINS. THIS WILL KEEP SURFACE HIGH PRESSURE OVER THE REGION THROUGH
THE WEEKEND RESULTING IN DRY CONDITIONS. THIS HIGH WILL ALSO
CONTINUE TO USHER IN MUCH COOLER TEMPERATURES WITH HIGHS ON FRIDAY
ONLY IN THE LOW TO MID 60S AND SLOWLY INCREASING TO THE UPPER 60S BY
SUNDAY. LOW TEMPERATURES WILL DIP DOWN INTO THE UPPER 30S AND LOW
40S OVER THE WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE THROUGH MIDWEEK AS A LOW
PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A WARM
AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
THROUGH THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......SC
AVIATION.....SC
SHORT TERM...MR
LONG TERM....RK/CB
MARINE.......MR
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 202243
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
643 PM EDT MON MAY 20 2013
.AVIATION...
//DISCUSSION...
ONGOING LINE OF THUNDERSTORMS AT THE START OF THE TAF PERIOD WILL
CONTINUE TO LIFT OFF TO THE NORTHEAST THIS EVENING. SUBSIDENCE IN
THE WAKE OF THIS INITIAL CONVECTIVE LINE SHOULD INHIBIT ADDITIONAL
CONVECTION THROUGH AT LEAST 06 TO 08Z. LOW LEVEL MOISTURE RETURN
LATE TONIGHT AND BUILDING INSTABILITY THROUGH THE DAY ON TUESDAY
WILL LEAD TO ADDITIONAL THUNDERSTORM DEVELOPMENT. TIMING AT THIS
STAGE IS VERY UNCERTAIN. WHILE THERE MAY BE SOME EARLY MORNING
THUNDERSTORM ACTIVITY...THUNDERSTORMS WILL BE CONFINED TO THE PEAK
IN THE DIURNAL HEATING CYCLE IN THE TAFS AT THIS TIME.
FOR DTW...THE POTENTIAL FOR THUNDERSTORMS IMPACTING METRO THIS
EVENING IS GROWING MORE UNCERTAIN AS THE MAIN LINE OF STORMS HAS
BEEN LIFTING OFF TO THE NE. GIVEN THE POOL OF INSTABILITY OVER METRO
DETROIT...SOME ADDITIONAL DEVELOPMENT OFF THE SOUTHERN END OF THE
CONVECTIVE LINE MAY YET OCCUR. ANY DEVELOPMENT WOULD MOST LIKELY
IMPACT METRO BETWEEN 00Z AND 03Z.
//DTW THRESHOLD THREATS...
* LOW CONFIDENCE IN THUNDERSTORM DEVELOPMENT THIS EVENING AND
MEDIUM CONFIDENCE ON TUESDAY.
&&
.PREV DISCUSSION...ISSUED 401 PM EDT MON MAY 20 2013
SHORT TERM...TODAY AND TONIGHT
WARM SECTOR AIRMASS FIRMLY ENTRENCHED ACROSS SE MICHIGAN THIS
AFTERNOON. LATEST OBSERVATIONS SHOWING TEMPERATURES MAKING A RUN TO
NEAR 90 DEGREES IN SOME LOCATIONS. DEEPER PLUME OF LOW LEVEL
MOISTURE BANKED ALONG THE INTERFACE OF THE UPPER RIDGE AXIS HOLDING
JUST TO THE EAST AND THE EXTENSIVE CLOSED LOW CIRCULATING OVER THE
DAKOTAS NOW EXTENDING THROUGHOUT LOWER MICHIGAN. THIS COMBINATION
TRANSLATING INTO A SOLID INSTABILITY AXIS...RECENT SPC MESOANALYSIS
INDICATING MLCAPE VALUES IN EXCESS 2000 J/KG. DESPITE THIS...
SOUTHEAST MICHIGAN STILL FEELING THE IMPACT OF THE NEARBY HIGHER
HEIGHT FIELD...AS NOTED BY THE 18Z DTX SOUNDING WHICH SHOWS A FAIRLY
STOUT 900-800 MB CAPPING INVERSION. THIS EFFECTIVELY CONTAINS THE
CONVECTIVE TEMPERATURE AT 90 DEGREE OR WARMER...LEAVING THE
PROSPECTS FOR SEEING CONVECTION CONDITIONALLY DEPENDENT ON REALIZING
SOME DEGREE OF FORCED ASCENT AND/OR CONSOLIDATING CONVECTIVELY
GENERATED COLD POOL DYNAMICS.
LINEAR EXPANSION OF CONVECTION UNDERWAY TO THE WEST/NORTHWEST
SUSTAINED BY A COMBINATION OF A PASSING MID LEVEL IMPULSE AND SOME
TYPE OF LAKE MICHIGAN MARINE INFLUENCE/BOUNDARY. THE POTENTIAL
REMAINS FOR SOME FORM OF EAST/NORTHEASTWARD EXPANSION OF THIS
ACTIVITY ALONG A FAVORABLY ALIGNED CORFIDI VECTOR AND INTO THE
INSTABILITY BUBBLE RESIDING OVER SE MICHIGAN. 12Z HI RES MODEL
SOLUTIONS CONTINUE TO POINT IN THIS DIRECTION. HOWEVER RELATIVELY
MODEST DEEP LAYER SHEAR EAST OF THIS LINE DOES LEAVE SOME QUESTION
AS TO THE ORGANIZATIONAL CAPACITY AND POTENTIAL COVERAGE OF ANY
INBOUND CONVECTION. NONETHELESS...GIVEN THE DEGREE OF INSTABILITY
IN PLACE...CONDITIONAL SEVERE THUNDERSTORM RISK CERTAINLY
EXISTS...ESPECIALLY ACROSS NORTHERN SECTIONS OF THE FORECAST AREA.
SEVERE THUNDERSTORM WATCH IS IN PLACE THROUGH 8 PM FROM WASHTENAW/
WAYNE COUNTIES NORTHWARD.
DECAYING CONVECTIVE COMPLEX LOCKED ONTO THE NEXT IN A SERIES OF WEAK
IMPULSES EJECTING AROUND THE UPPER MIDWEST LOW CONTINUES TO SHIFT
THROUGH NORTHERN ILLINOIS. A CONSIDERABLY LESS SUPPORTIVE
THERMODYNAMIC ENVIRONMENT ACROSS THAT CORRIDOR /DEWPOINTS IN THE
50S/ LEADING TO THIS WEAKENING TREND...BUT SOME POTENTIAL DOES EXIST
FOR RENEWED DEVELOPMENT AND UPSCALE GROWTH THROUGH THE LATTER HALF
OF THE EVENING AS THIS WAVE ENCOUNTERS THE BETTER INSTABILITY/
MOISTURE AXIS. THIS WILL CONTINUE TO SUPPORT A CHANCE POP MENTION.
THE OVERNIGHT/EARLY MORNING PERIOD BECOMES MORE MUDDLED...DEPENDENCE
ON PROPERLY DEFINING THE TRAJECTORY OF ADDITIONAL ILL-DEFINED
SHORTWAVE ENERGY AND/OR CONVECTIVE DEBRIS. EMERGING NOCTURNAL LOW
LEVEL JET FORCING AND SUSTAINABLE HIGHER LAPSE RATES LEND MORE
CONFIDENCE THAT SOME FORM OF ADDITIONAL CONVECTION WILL TAKE AIM ON
THE REGION LATE TONIGHT...BUT DEFINING THE DETAILS OF
LOCATION/TIMING AND COVERAGE REMAINS A CHALLENGE. A MILD NIGHT
AHEAD GIVEN THE ELEVATED DEWPOINTS...LOWS MID TO UPPER 60S.
LONG TERM...TUESDAY THROUGH SUNDAY
THE MAIN DRIVER OF THE WEATHER TUESDAY WILL BE THE MOMENTUM TRANSFER
THAT WILL OCCUR OF UPPER LEVEL JET ENERGY OVER THE RIDGE AXIS.
ORIENTATION OF UPPER LEVEL RIDGING OVER NORTHERN GREAT LAKES AND
ONTARIO WILL THEN CHANGE FROM CYCLONIC TO ANTICYCLONIC CURVATURE.
FUNDAMENTALLY...THIS WILL PUT SOUTHEASTERN MICHIGAN IN A DIFFERENT
REGIME AS THE AREA WILL BECOME IN CLOSER PROXIMITY TO THE UPPER
LEVEL JET AXIS. PROXIMITY TO THE UPPER LEVEL JET AXIS IS NEVER A
TRIVIAL QUESTION...BECAUSE A CLOSER PROXIMITY MEANS ONE IS CLOSER TO
THE FIREHOSE OR PATH OF EMBEDDED SHORTWAVE ENERGY. HOWEVER...WHAT IS
A MORE DIFFICULT DETERMINATION IS THE OVERALL CRISPNESS OR EDGE
QUALITY TO THE UPPER LEVEL RIDGE. IN OTHER WORDS...A GREATER
POTENTIAL WILL EXIST FOR PERIODIC SHOWERS AND THUNDERSTORMS
THROUGHOUT TUESDAY AND TUESDAY NIGHT.
THE SEVERE WEATHER THREAT FOR TUESDAY WILL BE PARTIALLY INFLUENCED
BY AREAL COVERAGE AND DURATION OF ONGOING THUNDERSTORMS DURING THE
PRE-NOON TIMEFRAME. HOWEVER...GIVEN LATE MAY NUMBER OF DAYLIGHT
HOURS AND SOLAR INTENSITY...ANY BREAK IN CLOUD COVER WILL ALLOW
SURFACE TEMPERATURES TO CLIMB AND CAPES TO BUILD. THERE IS SURELY
CONTAMINATION OF THE THERMODYNAMIC ENVIRONMENT IN THE MODELS BUT
CONFIDENCE IS HIGH THAT 700-500 MB LAPSE RATES WILL NOT BE ANYWHERE
NEAR AS PRISTINE. LIKELY NOT MOIST ADIABATIC BUT CERTAINLY NOT 7.5-8
DEG C/KM EITHER. SBCAPES ARE EXPECTED TO REACH 1000 J/KG WITH
MLCAPES LIKELY STRUGGLING TO REACH THAT SAME THRESHOLD. CLOSER
PROXIMITY TO JET WILL BRING SOLID 30-40 KNOTS OF 0-6KM BULK
SHEAR....GOOD FOR A POTENTIAL OF STRONG TO POSSIBLY SEVERE
THUNDERSTORMS FOR DAMAGING WIND GUSTS AND LARGE HAIL.
A CONVECTIVELY MODULATED BOUNDARY LAYER AND HIGHER SPEED FLOW
OVERHEAD MAKES THE TIMING OF INDIVIDUAL FORCING ELEMENTS DIFFICULT.
WILL OFFER A THOUGHT OR TWO TO THINK ABOUT DESPITE THE NOISE. SOME
MODEL DATA SUGGESTS THAT DIFFERENTIAL AIRMASS RECOVERY MAY OCCUR
PRIMARILY FROM THE IRISH HILLS TO THE SOUTHEAST. A PERTURBATION TO
THE FLOW OR RIBBON OF ENHANCED CONVERGENCE IS HIGHLIGHTED ON SOME
REMNANT CONVECTIVE SHORTWAVE ENERGY IS HIGHLIGHTED TO TRACK THROUGH
TOMORROW IN SOUTHWEST FLOW. BEST IDEA ON TIMING FOR STRONG TO
SEVERE STORMS IS 19-23Z. ALL OF SOUTHEASTERN MICHIGAN IS IN THE
SLIGHT RISK ON SWODY2.
CONVECTION THAT DEVELOPS DURING THE DAY ON TUESDAY WILL BEGIN TO
DIMINISH BY EVENING. A LULL IN THE THUNDERSTORMS DEVELOP FOR THE
OVERNIGHT PERIOD AS ONE LOW PRESSURE SYSTEM MOVES OFF INTO CANADA
AND ANOTHER SECONDARY LOW DEEPENS OVER IOWA AND NORTHERN ILLINOIS.
HOWEVER...CURRENT MODEL SOUNDINGS ARE INDICATING MORE LOW LEVEL
MOISTURE IN BETWEEN THESE TWO LOW PRESSURE SYSTEMS THAN PREVIOUS
RUNS SO HAVE INCREASED THE FORECAST TO HIGH CHANCE POPS TO ACCOUNT
FOR ANY SHOWERS THAT WILL CONTINUE THROUGH THE OVERNIGHT PERIOD.
CURRENT MODEL RUNS ARE FAIRLY WELL IN AGREEMENT WITH ONE ANOTHER
BRINGING THE CENTER OF THE SURFACE LOW WILL ACROSS CENTRAL MICHIGAN
ON WEDNESDAY AS THE UPPER LOW MERGES INTO THE FLOW OVER CANADA. THIS
WILL BRING A CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH
THE DAY. AS THE COLD FRONT FINALLY MOVES OVER SOUTHERN MICHIGAN ON
WEDNESDAY NIGHT...RAIN WILL CONTINUE THROUGH WEDNESDAY NIGHT. THE
BACK END OF THIS LOW WILL LACK ANY SUPPORT FOR ORGANIZED CONVECTION
ON THURSDAY WITH ONLY RAIN CONTINUING FOR MOST OF THE DAY ON
THURSDAY. COLDER AIR BEGINS TO FILTER IN BEHIND THE PASSING LOW ON
THURSDAY RESULTING IN HIGH TEMPERATURES TO ONLY BE IN THE UPPER 50S TO
LOW 60S ACROSS THE CWA.
A FEW LINGERING RAIN SHOWERS WILL PERSIST INTO THE THURSDAY NIGHT
TIME FRAME BEFORE AN UPPER LEVEL RIDGE BUILDS INTO THE CENTRAL
PLAINS. THIS WILL KEEP SURFACE HIGH PRESSURE OVER THE REGION THROUGH
THE WEEKEND RESULTING IN DRY CONDITIONS. THIS HIGH WILL ALSO
CONTINUE TO USHER IN MUCH COOLER TEMPERATURES WITH HIGHS ON FRIDAY
ONLY IN THE LOW TO MID 60S AND SLOWLY INCREASING TO THE UPPER 60S BY
SUNDAY. LOW TEMPERATURES WILL DIP DOWN INTO THE UPPER 30S AND LOW
40S OVER THE WEEKEND.
MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE THROUGH MIDWEEK AS A LOW
PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A WARM
AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
THROUGH THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....SC
SHORT TERM...MR
LONG TERM....RK/CB
MARINE.......MR
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 202001
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
401 PM EDT MON MAY 20 2013
.SHORT TERM...TODAY AND TONIGHT
WARM SECTOR AIRMASS FIRMLY ENTRENCHED ACROSS SE MICHIGAN THIS
AFTERNOON. LATEST OBSERVATIONS SHOWING TEMPERATURES MAKING A RUN TO
NEAR 90 DEGREES IN SOME LOCATIONS. DEEPER PLUME OF LOW LEVEL
MOISTURE BANKED ALONG THE INTERFACE OF THE UPPER RIDGE AXIS HOLDING
JUST TO THE EAST AND THE EXTENSIVE CLOSED LOW CIRCULATING OVER THE
DAKOTAS NOW EXTENDING THROUGHOUT LOWER MICHIGAN. THIS COMBINATION
TRANSLATING INTO A SOLID INSTABILITY AXIS...RECENT SPC MESOANALYSIS
INDICATING MLCAPE VALUES IN EXCESS 2000 J/KG. DESPITE THIS...
SOUTHEAST MICHIGAN STILL FEELING THE IMPACT OF THE NEARBY HIGHER
HEIGHT FIELD...AS NOTED BY THE 18Z DTX SOUNDING WHICH SHOWS A FAIRLY
STOUT 900-800 MB CAPPING INVERSION. THIS EFFECTIVELY CONTAINS THE
CONVECTIVE TEMPERATURE AT 90 DEGREE OR WARMER...LEAVING THE
PROSPECTS FOR SEEING CONVECTION CONDITIONALLY DEPENDENT ON REALIZING
SOME DEGREE OF FORCED ASCENT AND/OR CONSOLIDATING CONVECTIVELY
GENERATED COLD POOL DYNAMICS.
LINEAR EXPANSION OF CONVECTION UNDERWAY TO THE WEST/NORTHWEST
SUSTAINED BY A COMBINATION OF A PASSING MID LEVEL IMPULSE AND SOME
TYPE OF LAKE MICHIGAN MARINE INFLUENCE/BOUNDARY. THE POTENTIAL
REMAINS FOR SOME FORM OF EAST/NORTHEASTWARD EXPANSION OF THIS
ACTIVITY ALONG A FAVORABLY ALIGNED CORFIDI VECTOR AND INTO THE
INSTABILITY BUBBLE RESIDING OVER SE MICHIGAN. 12Z HI RES MODEL
SOLUTIONS CONTINUE TO POINT IN THIS DIRECTION. HOWEVER RELATIVELY
MODEST DEEP LAYER SHEAR EAST OF THIS LINE DOES LEAVE SOME QUESTION
AS TO THE ORGANIZATIONAL CAPACITY AND POTENTIAL COVERAGE OF ANY
INBOUND CONVECTION. NONETHELESS...GIVEN THE DEGREE OF INSTABILITY
IN PLACE...CONDITIONAL SEVERE THUNDERSTORM RISK CERTAINLY
EXISTS...ESPECIALLY ACROSS NORTHERN SECTIONS OF THE FORECAST AREA.
SEVERE THUNDERSTORM WATCH IS IN PLACE THROUGH 8 PM FROM WASHTENAW/
WAYNE COUNTIES NORTHWARD.
DECAYING CONVECTIVE COMPLEX LOCKED ONTO THE NEXT IN A SERIES OF WEAK
IMPULSES EJECTING AROUND THE UPPER MIDWEST LOW CONTINUES TO SHIFT
THROUGH NORTHERN ILLINOIS. A CONSIDERABLY LESS SUPPORTIVE
THERMODYNAMIC ENVIRONMENT ACROSS THAT CORRIDOR /DEWPOINTS IN THE
50S/ LEADING TO THIS WEAKENING TREND...BUT SOME POTENTIAL DOES EXIST
FOR RENEWED DEVELOPMENT AND UPSCALE GROWTH THROUGH THE LATTER HALF
OF THE EVENING AS THIS WAVE ENCOUNTERS THE BETTER INSTABILITY/
MOISTURE AXIS. THIS WILL CONTINUE TO SUPPORT A CHANCE POP MENTION.
THE OVERNIGHT/EARLY MORNING PERIOD BECOMES MORE MUDDLED...DEPENDENCE
ON PROPERLY DEFINING THE TRAJECTORY OF ADDITIONAL ILL-DEFINED
SHORTWAVE ENERGY AND/OR CONVECTIVE DEBRIS. EMERGING NOCTURNAL LOW
LEVEL JET FORCING AND SUSTAINABLE HIGHER LAPSE RATES LEND MORE
CONFIDENCE THAT SOME FORM OF ADDITIONAL CONVECTION WILL TAKE AIM ON
THE REGION LATE TONIGHT...BUT DEFINING THE DETAILS OF
LOCATION/TIMING AND COVERAGE REMAINS A CHALLENGE. A MILD NIGHT
AHEAD GIVEN THE ELEVATED DEWPOINTS...LOWS MID TO UPPER 60S.
&&
.LONG TERM...TUESDAY THROUGH SUNDAY
THE MAIN DRIVER OF THE WEATHER TUESDAY WILL BE THE MOMENTUM TRANSFER
THAT WILL OCCUR OF UPPER LEVEL JET ENERGY OVER THE RIDGE AXIS.
ORIENTATION OF UPPER LEVEL RIDGING OVER NORTHERN GREAT LAKES AND
ONTARIO WILL THEN CHANGE FROM CYCLONIC TO ANTICYCLONIC CURVATURE.
FUNDAMENTALLY...THIS WILL PUT SOUTHEASTERN MICHIGAN IN A DIFFERENT
REGIME AS THE AREA WILL BECOME IN CLOSER PROXIMITY TO THE UPPER
LEVEL JET AXIS. PROXIMITY TO THE UPPER LEVEL JET AXIS IS NEVER A
TRIVIAL QUESTION...BECAUSE A CLOSER PROXIMITY MEANS ONE IS CLOSER TO
THE FIREHOSE OR PATH OF EMBEDDED SHORTWAVE ENERGY. HOWEVER...WHAT IS
A MORE DIFFICULT DETERMINATION IS THE OVERALL CRISPNESS OR EDGE
QUALITY TO THE UPPER LEVEL RIDGE. IN OTHER WORDS...A GREATER
POTENTIAL WILL EXIST FOR PERIODIC SHOWERS AND THUNDERSTORMS
THROUGHOUT TUESDAY AND TUESDAY NIGHT.
THE SEVERE WEATHER THREAT FOR TUESDAY WILL BE PARTIALLY INFLUENCED
BY AREAL COVERAGE AND DURATION OF ONGOING THUNDERSTORMS DURING THE
PRE-NOON TIMEFRAME. HOWEVER...GIVEN LATE MAY NUMBER OF DAYLIGHT
HOURS AND SOLAR INTENSITY...ANY BREAK IN CLOUD COVER WILL ALLOW
SURFACE TEMPERATURES TO CLIMB AND CAPES TO BUILD. THERE IS SURELY
CONTAMINATION OF THE THERMODYNAMIC ENVIRONMENT IN THE MODELS BUT
CONFIDENCE IS HIGH THAT 700-500 MB LAPSE RATES WILL NOT BE ANYWHERE
NEAR AS PRISTINE. LIKELY NOT MOIST ADIABATIC BUT CERTAINLY NOT 7.5-8
DEG C/KM EITHER. SBCAPES ARE EXPECTED TO REACH 1000 J/KG WITH
MLCAPES LIKELY STRUGGLING TO REACH THAT SAME THRESHOLD. CLOSER
PROXIMITY TO JET WILL BRING SOLID 30-40 KNOTS OF 0-6KM BULK
SHEAR....GOOD FOR A POTENTIAL OF STRONG TO POSSIBLY SEVERE
THUNDERSTORMS FOR DAMAGING WIND GUSTS AND LARGE HAIL.
A CONVECTIVELY MODULATED BOUNDARY LAYER AND HIGHER SPEED FLOW
OVERHEAD MAKES THE TIMING OF INDIVIDUAL FORCING ELEMENTS DIFFICULT.
WILL OFFER A THOUGHT OR TWO TO THINK ABOUT DESPITE THE NOISE. SOME
MODEL DATA SUGGESTS THAT DIFFERENTIAL AIRMASS RECOVERY MAY OCCUR
PRIMARILY FROM THE IRISH HILLS TO THE SOUTHEAST. A PERTURBATION TO
THE FLOW OR RIBBON OF ENHANCED CONVERGENCE IS HIGHLIGHTED ON SOME
REMNANT CONVECTIVE SHORTWAVE ENERGY IS HIGHLIGHTED TO TRACK THROUGH
TOMORROW IN SOUTHWEST FLOW. BEST IDEA ON TIMING FOR STRONG TO
SEVERE STORMS IS 19-23Z. ALL OF SOUTHEASTERN MICHIGAN IS IN THE
SLIGHT RISK ON SWODY2.
CONVECTION THAT DEVELOPS DURING THE DAY ON TUESDAY WILL BEGIN TO
DIMINISH BY EVENING. A LULL IN THE THUNDERSTORMS DEVELOP FOR THE
OVERNIGHT PERIOD AS ONE LOW PRESSURE SYSTEM MOVES OFF INTO CANADA
AND ANOTHER SECONDARY LOW DEEPENS OVER IOWA AND NORTHERN ILLINOIS.
HOWEVER...CURRENT MODEL SOUNDINGS ARE INDICATING MORE LOW LEVEL
MOISTURE IN BETWEEN THESE TWO LOW PRESSURE SYSTEMS THAN PREVIOUS
RUNS SO HAVE INCREASED THE FORECAST TO HIGH CHANCE POPS TO ACCOUNT
FOR ANY SHOWERS THAT WILL CONTINUE THROUGH THE OVERNIGHT PERIOD.
CURRENT MODEL RUNS ARE FAIRLY WELL IN AGREEMENT WITH ONE ANOTHER
BRINGING THE CENTER OF THE SURFACE LOW WILL ACROSS CENTRAL MICHIGAN
ON WEDNESDAY AS THE UPPER LOW MERGES INTO THE FLOW OVER CANADA. THIS
WILL BRING A CONTINUED CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH
THE DAY. AS THE COLD FRONT FINALLY MOVES OVER SOUTHERN MICHIGAN ON
WEDNESDAY NIGHT...RAIN WILL CONTINUE THROUGH WEDNESDAY NIGHT. THE
BACK END OF THIS LOW WILL LACK ANY SUPPORT FOR ORGANIZED CONVECTION
ON THURSDAY WITH ONLY RAIN CONTINUING FOR MOST OF THE DAY ON
THURSDAY. COLDER AIR BEGINS TO FILTER IN BEHIND THE PASSING LOW ON
THURSDAY RESULTING IN HIGH TEMPERATURES TO ONLY BE IN THE UPPER 50S TO
LOW 60S ACROSS THE CWA.
A FEW LINGERING RAIN SHOWERS WILL PERSIST INTO THE THURSDAY NIGHT
TIME FRAME BEFORE AN UPPER LEVEL RIDGE BUILDS INTO THE CENTRAL
PLAINS. THIS WILL KEEP SURFACE HIGH PRESSURE OVER THE REGION THROUGH
THE WEEKEND RESULTING IN DRY CONDITIONS. THIS HIGH WILL ALSO
CONTINUE TO USHER IN MUCH COOLER TEMPERATURES WITH HIGHS ON FRIDAY
ONLY IN THE LOW TO MID 60S AND SLOWLY INCREASING TO THE UPPER 60S BY
SUNDAY. LOW TEMPERATURES WILL DIP DOWN INTO THE UPPER 30S AND LOW
40S OVER THE WEEKEND.
&&
.MARINE...
MODEST SOUTHERLY WINDS WILL REMAIN IN PLACE THROUGH MIDWEEK AS A LOW
PRESSURE SYSTEM SLOWLY LIFTS EAST OUT OF THE UPPER MIDWEST. A WARM
AND UNSTABLE ENVIRONMENT WILL BRING A CHANCE OF THUNDERSTORMS
THROUGH THIS TIME. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS
BY THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST.
&&
.AVIATION...ISSUED 110 PM EDT MON MAY 20 2013
//DISCUSSION...
SOUTHEAST MICHIGAN WELL WITHIN A DESTABILIZING WARM SECTOR
ENVIRONMENT THIS AFTERNOON. DIURNAL CU GROWTH/EXPANSION WILL
CONTINUE THROUGH THE AFTERNOON...CIGS SETTLING INTO THE 4-5K FT
RANGE. A DEEPENING MIXED LAYER WILL LEAD TO SOME SOUTHERLY WIND
GUSTS IN THE 20 KNOTS RANGE THROUGH PEAK HEATING. MAIN QUESTION
WITHIN THIS ENVIRONMENT REMAINS DEFINING THE PROSPECTS FOR
THUNDERSTORM DEVELOPMENT...BOTH LATE AFTERNOON INTO THE EVENING AND
AGAIN LATE TONIGHT INTO TUESDAY. GREATEST POTENTIAL IN THE NEARER
TERM WILL EXIST ROUGHLY 20Z-23Z NORTH AND 23Z-02Z ACROSS METRO
DETROIT...SUPPORTED BY A MID LEVEL WAVE WORKING INTO THE UNSTABLE
CONDITIONS. WHILE OVERALL CONFIDENCE REMAINS MODEST AS TO THE
EXPECTED COVERAGE...WILL GO AHEAD AND OUTLOOK THE MOST LIKELY
WINDOW WITH A TEMPO MENTION.
FOR DTW...EXPANDING DIURNAL CU FIELD WILL WORK INTO THE TERMINAL
OVER THE NEXT 1-2 HOURS...LEAVING A PREVAILING SUB-5000 FT CEILING
FOR SEVERAL HOURS. SOME CONCERN THAT DEVELOPING THUNDERSTORM
ACTIVITY LATE THIS AFTERNOON/EVENING WILL TEND TO TRACK NORTH/WEST
OF THE TERMINAL. HOWEVER THE POTENTIAL FOR A THUNDERSTORM TO IMPACT
THE TERMINAL IS HIGH ENOUGH TO HIGHLIGHT A PERIOD...GREATEST WINDOW
23Z-02Z.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILINGS BELOW 5KFT THIS AFTERNOON AND EVENING.
* MEDIUM CONFIDENCE IN THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON
AND EVENING.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
SHORT TERM...MR
LONG TERM....RK/CB
MARINE.......MR
AVIATION.....MR
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 201710
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
110 PM EDT MON MAY 20 2013
.AVIATION...
//DISCUSSION...
SOUTHEAST MICHIGAN WELL WITHIN A DESTABLIZING WARM SECTOR
ENVIRONMENT THIS AFTERNOON. DIURNAL CU GROWTH/EXPANSION WILL
CONTINUE THROUGH THE AFTERNOON...CIGS SETTLING INTO THE 4-5K FT
RANGE. A DEEPENING MIXED LAYER WILL LEAD TO SOME SOUTHERLY WIND
GUSTS IN THE 20 KNOTS RANGE THROUGH PEAK HEATING. MAIN QUESTION
WITHIN THIS ENVIRONMENT REMAINS DEFINING THE PROSPECTS FOR
THUNDERSTORM DEVELOPMENT...BOTH LATE AFTERNOON INTO THE EVENING AND
AGAIN LATE TONIGHT INTO TUESDAY. GREATEST POTENTIAL IN THE NEARER
TERM WILL EXIST ROUGHLY 20Z-23Z NORTH AND 23Z-02Z ACROSS METRO
DETROIT...SUPPORTED BY A MID LEVEL WAVE WORKING INTO THE UNSTABLE
CONDITIONS. WHILE OVERALL CONFIDENCE REMAINS MODEST AS TO THE
EXPECTED COVERAGE...WILL GO AHEAD AND OUTLOOK THE MOST LIKELY
WINDOW WITH A TEMPO MENTION.
FOR DTW...EXPANDING DIURNAL CU FIELD WILL WORK INTO THE TERMINAL
OVER THE NEXT 1-2 HOURS...LEAVING A PREVAILING SUB-5000 FT CEILING
FOR SEVERAL HOURS. SOME CONCERN THAT DEVELOPING THUNDERSTORM
ACTIVITY LATE THIS AFTERNOON/EVENING WILL TEND TO TRACK NORTH/WEST
OF THE TERMINAL. HOWEVER THE POTENTIAL FOR A THUNDERSTORM TO IMPACT
THE TERMINAL IS HIGH ENOUGH TO HIGHTLIGHT A PERIOD...GREATEST WINDOW
23Z-02Z.
//DTW THRESHOLD THREATS...
* HIGH CONFIDENCE IN CEILINGS BELOW 5KFT THIS AFTERNOON AND EVENING.
* MEDIUM CONFIDENCE IN THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON
AND EVENING.
&&
.PREV DISCUSSION...ISSUED 1039 AM EDT MON MAY 20 2013
UPDATE...
WARM FRONTAL BOUNDARY AND ATTENDANT 925 MB MOISTURE GRADIENT
SLIPPING THROUGH SE MICHIGAN LATE THIS MORNING. LOW LEVEL ASCENT
INTO THE EXISTING STEEPER LAPSE RATE ENVIRONMENT RESIDING WITHIN THE
925-800 MB LAYER /PER 12Z DTX SOUNDING/ PROVING SUFFICIENT TOWARD
GENERATING A NARROW BAND OF ISOLATED/SCATTERED CONVECTIVE
SHOWERS/EMBEDDED THUNDER. THIS AXIS WILL PERSIST OVER THE NEXT 2-3
HOURS AS IT PROPAGATES ACROSS AREAS EAST OF I-75...HEAVIEST CELLS
GENERATING SOME BRIEF HEAVY DOWNPOURS.
FOCUS INTO THIS AFTERNOON/EVENING REMAINS ON CONVECTIVE POTENTIAL
AND CORRESPONDING SEVERE RISK. ONGOING MODULATION OF BOTH UPSTREAM
AND AMBIENT THERMODYNAMIC CONDITIONS VIA STEADY THETA-E TRANSPORT
INTO THE DIURNAL HEATING CYCLE STILL EXPECTED TO LEAVE A MODERATELY
UNSTABLE ENVIRONMENT CARRYING MLCAPE UPWARD OF 1500-2000 J/KG BY
MID-LATE AFTERNOON FROM EASTERN IL/WESTERN IN INTO LOWER MICHIGAN.
PERIOD OF FULL INSOLATION IN THE WAKE OF THE AFOREMENTIONED WARM
FRONTAL PASSAGE WILL ALLOW TEMPERATURES TO PUSH THE MIDDLE AND
UPPER 80S IN MANY LOCALES BY LATE AFTERNOON...WHILE DEWPOINTS INCH
UP INTO THE UPPER 60S. DEFINED ASCENT AND MOISTURE TRANSPORT
EVIDENT IN WATER VAPOR ALONG THE NOSE OF A STRONG MID LEVEL WAVE
AND ASSOCIATED 700 MB SPEED MAX NOW WORKING INTO ILLINOIS. THIS
WOULD SEEMINGLY PROVIDE THE GREATEST OPPORTUNITY FOR AN EXPANDING
REGION OF CONVECTION TO FOCUS AS IT ENTERS A MORE PRISTINE
THERMODYNAMIC ENVIRONMENT EXISTING DOWNSTREAM THROUGHOUT LOWER
MICHIGAN. WORTH NOTING THAT AN ANALYSIS OF MOST RECENT HIRES MODEL
GUIDANCE SUGGEST A LAKE MICHIGAN DRIVEN LEE TROUGH/CONVERGENCE
AXIS COULD ALSO BE A CATALYST FOR CONVECTIVE GROWTH...WITH THIS
ACTIVITY THEN TENDING TO PROPAGATE EAST INTO THE GROWING
INSTABILITY BUBBLE. WHILE DEEP LAYER SHEAR REMAINS BELOW 30
KNOTS...THE BACKGROUND WIND PROFILE REMAINS SUFFICIENT TO SUSTAIN
ORGANIZED CONVECTION AND PROVIDE A RISK OF DAMAGING WINDS AND
LARGE HAIL AFTER 19Z.
PREV DISCUSSION...ISSUED 351 AM EDT MON MAY 20 2013
SHORT TERM...TODAY AND TONIGHT
UPPER LEVEL RIDGE AXIS WILL BE IN PLACE ACROSS THE CENTRAL GREAT
LAKES THIS MORNING. HOWEVER A HEALTHY SURGE OF HIGHER THETA-E AIR IN
THE 925 TO 850 MB LEVEL AND SYSTEM RELATIVE ISENTROPIC LIFT AT 310K
WILL TRACK THROUGH MICHIGAN DURING THE EARLY MORNING HOURS WITH
SEVERAL LOCAL AND NWP MODELS GENERATING SHOWERS BETWEEN 09-15Z.
DESPITE THE LOW LEVEL LIFT...THE UPPER LEVEL RIDGING AND DRY AIR IN
PLACE ARE A CONCERN AS WELL AS THE THETA-E SURGE WEAKENING AS IT
MOVES THROUGH THE AREA. WITH THESE FACTORS IN MIND POPS IN THE LOW
CHANCY RANGE SEEM APPROPRIATE AS THE LOW LEVEL LIFT CANNOT BE
COMPLETELY DISCARDED. MUCAPE VALUES EARLY THIS MORNING WILL BE
AROUND 1000 J/KG...WARRANTING THE INCLUSION OF THUNDER WITH THE RAIN
SHOWERS. GIVEN THE ELEVATED NATURE OF THIS MORNINGS CONVECTION AND
WEAK WIND FIELD THROUGH THE SOUNDING...SEVERE WEATHER IS NOT
EXPECTED TO BE AN ISSUE WITH THE EARLY DEVELOPMENT IF IT
MATERIALIZES.
AFTER THIS INITIAL SURGE THERE WILL BE A QUIET PERIOD LATER THIS
MORNING AND INTO THE EARLY AFTERNOON HOURS WITH THE RIDGE AXIS STILL
OVER THE CENTRAL GREAT LAKES...ALLOWING HIGH TEMPERATURES TO GET
INTO THE MIDDLE TO UPPER 80S AWAY FROM THE GREAT LAKES AS 850 MB
TEMPERATURES RISE INTO THE MIDDLE TO UPPER TEENS.
LATER THIS AFTERNOON AND INTO THIS EVENING A PIECE OF SHORTWAVE
ENERGY TRACKS THROUGH THE CENTRAL GREAT LAKES WHILE THE
AFOREMENTIONED RIDGE SLIDES EAST TOWARDS THE EASTERN GREAT LAKES AND
THE 850 MB LOW LEVEL JET CRANKS TO AROUND 30 KNOTS WITH THE NOSE
POINTED TOWARDS SOUTHEAST MICHIGAN. MUCAPE VALUES DURING THIS PERIOD
HOVER AROUND 2000 J/KG WITH 0-6KM BULK SHEAR VALUES OF 20 TO 30
KNOTS. SLIGHT RISK FOR SEVERE WEATHER CONTINUES WITH THE SPC DAY ONE
OUTLOOK WITH THE MAIN CONVECTIVE MODE EXPECTED TO BE LINEAR
STRUCTURES WITH SUPERCELLS POSSIBLE GIVEN THE DIRECTIONAL TURNING IN
THE LOW LEVELS. DAMAGING WINDS AND LARGE HAIL ARE EXPECTED TO BE THE
MAIN THREAT...WITH SOME ISOLATED TORNADOES POSSIBLE IF CONVECTION
CAN FIRE EARLY ENOUGH AND TAKE ADVANTAGE OF THE BETTER INSTABILITY
AND LOW LEVEL SHEAR.
WITH ONGOING CONVECTION OVERNIGHT AND ABUNDANT CLOUD COVER IN THE
WARM SECTOR...OVERNIGHT LOWS ARE EXPECTED TO STAY IN THE 60S TONIGHT.
LONG TERM...TUESDAY THROUGH SUNDAY
ACTIVE WEATHER PATTERN OVER SE MI TUESDAY THROUGH WEDNESDAY NIGHT
WITH STRONG TO SEVERE STORMS POSSIBLE ON TUESDAY. SHOWERS WILL TAPER
OFF THURSDAY BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM BUILDS
INTO THE REGION THROUGH THE HOLIDAY WEEKEND LEAVING US COOL AND DRY.
MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT OVERALL WITH THE LARGE
SCALE PATTERN AND THE STACKED LOW PRESSURE SYSTEMS OVER THE NORTHERN
PLAINS. THIS DOES NOT LEAD TO A HIGH CONFIDENCE FORECAST THOUGH AS
PERIODS OF SHOWERS AND THUNDERSTORMS WILL BE FORCED BY SMALL SCALE
SHORTWAVES ROTATING AROUND THE PARENT UPPER LOW WHICH ARE DIFFICULT
TO TIME THIS FAR OUT.
TUESDAY...LOOKS LIKE MULTIPLE ROUNDS OF STORMS WILL PASS THROUGH SE
MI THIS DAY. FIRST WE MAY HAVE TO DEAL WITH A CONVECTIVE COMPLEX
LINGERING INTO THE MORNING HOURS FROM THE OVERNIGHT. MAY TRY TO
CLEAR OUT DURING THE EARLY AFTERNOON BEFORE A SHORTWAVE ROUNDING THE
BASE OF THE UPPER LEVEL TROUGH REACHES THE AREA. MEANWHILE A SFC LOW
PRESSURE CENTER LOOKS TO TRACK THROUGH NORTHERN MI. THE
AFTERNOON TIMING WILL BE FAVORABLE FOR STORMS TO DEVELOP WITH A
STRONG DIURNAL COMPONENT INCREASING LOW LEVEL LAPSE RATES. OTHER
FAVORABLE PARAMETERS ARE MUCAPE VALUES PEAKING AROUND 1500 J/KG...30
TO 40 KNOTS OF EFFECTIVE SHEAR...STRONG LOW/HIGH LEVEL LAPSE
RATES...SHOWALTER INDEX AROUND -1...AND UPPER LEVEL SUPPORT AS WELL
WITH THE JET INCHING CLOSER TO MID MI AND WEAKENING UPPER LEVEL
DIFFLUENCE. HIGH PWATS REACHING 1.6 INCHES WILL SUPPORT HEAVY
RAINFALL AS WELL. SPC HAS INCLUDED SE MI IN THE SLIGHT RISK AREA
WHICH SEEMS MORE THAN WARRANTED AT THIS TIME.
MODELS HAVE BEEN ADVERTISING ANOTHER LULL TUESDAY NIGHT FOR A COUPLE
RUNS NOW...INCLUDING THE MOST RECENT 00Z ECMWF...SO FEEL COMFORTABLE
WITH THE INHERITED CHANCE POPS.
BY WEDNESDAY...THE ENTIRE PATTERN BECOMES MUCH MORE PROGRESSIVE AS
OUR ONCE CUT OFF UPPER LOW BEGINS PHASING WITH NORTHERN STREAM
TROUGHING OVER ONTARIO. BY NOW THE SFC LOW HAS BEEN VERY SHEARED OUT
WITH SEVERAL NEW CENTERS TRYING TO FOR ALONG THE MAIN BAROCLINIC
ZONE. THE STRONGEST OF WHICH LOOKS TO FORM OVER THE CENTRAL
MISSISSIPPI VALLEY. SHOWERS AND THUNDERSTORMS WILL BE LIKELY ONCE
AGAIN AS THIS LOW LIFTS NE INTO THE REGION. ISENTROPIC ASCENT WILL
INCREASE OVER THE STATE DUE TO THE LOW RUNNING INTO WARM FRONT THAT
HAS BEEN DRAPED OVER NORTHERN MI THROUGH THE WEEK. THE TRIPLE POINT
WILL PASS NORTHEASTWARD SOMEWHERE CLOSE TO THE MI/OH BORDER IN THE
EVENING.
AFTER DEALING WITH SOME LINGERING SHOWERS ON THE BACKSIDE OF THE
SYSTEM...HIGH PRESSURE WILL DROP IN FROM CANADA PUTTING AN END TO
THE WET STRETCH OF WEATHER. IT WILL ALSO USHER COOLER TEMPS...IN THE
60S...BACK INTO THE GREAT LAKES. TROUGHING OVER BOTH COASTS WILL
HELP AMPLIFY THE RIDGE OVER THE CENTRAL CONUS THROUGH THE WEEKEND.
MARINE...
A LOW PRESSURE SYSTEM OVER THE NORTHERN PLAINS WILL DRIFT TOWARD THE
GREAT LAKES LAYING OUT A WARM FRONT ACROSS CENTRAL MI. THIS FRONT
WILL STALL OVER THE AREA THROUGH MIDWEEK AS THE LOW TRACKS ALONG IT.
WINDS SOUTH OF THE FRONT WILL REMAIN SOUTHERLY WHILE WINDS TO THE
NORTH WILL BACK TO THE EAST AND INCREASE SLIGHTLY. THIS WILL LEAD TO
HIGHER WAVES OVER NORTHERN LAKE HURON WHILE THE SOUTHERN
BASIN...LAKE ST CLAIR AND LAKE ERIE KEEP WAVES GENERALLY UNDER 2
FEET. THIS LOW WILL BRING SCATTERED THUNDERSTORMS TODAY THROUGH
THURSDAY. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS BY
THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
AVIATION.....MR
UPDATE.......MR
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
000
FXUS63 KDTX 201439
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1039 AM EDT MON MAY 20 2013
.UPDATE...
WARM FRONTAL BOUNDARY AND ATTENDANT 925 MB MOISTURE GRADIENT
SLIPPING THROUGH SE MICHIGAN LATE THIS MORNING. LOW LEVEL ASCENT
INTO THE EXISTING STEEPER LAPSE RATE ENVIRONMENT RESIDING WITHIN THE
925-800 MB LAYER /PER 12Z DTX SOUNDING/ PROVING SUFFICIENT TOWARD
GENERATING A NARROW BAND OF ISOLATED/SCATTERED CONVECTIVE
SHOWERS/EMBEDDED THUNDER. THIS AXIS WILL PERSIST OVER THE NEXT 2-3
HOURS AS IT PROPAGATES ACROSS AREAS EAST OF I-75...HEAVIEST CELLS
GENERATING SOME BRIEF HEAVY DOWNPOURS.
FOCUS INTO THIS AFTERNOON/EVENING REMAINS ON CONVECTIVE POTENTIAL
AND CORRESPONDING SEVERE RISK. ONGOING MODULATION OF BOTH UPSTREAM
AND AMBIENT THERMODYNAMIC CONDITIONS VIA STEADY THETA-E TRANSPORT
INTO THE DIURNAL HEATING CYCLE STILL EXPECTED TO LEAVE A MODERATELY
UNSTABLE ENVIRONMENT CARRYING MLCAPE UPWARD OF 1500-2000 J/KG BY
MID-LATE AFTERNOON FROM EASTERN IL/WESTERN IN INTO LOWER MICHIGAN.
PERIOD OF FULL INSOLATION IN THE WAKE OF THE AFOREMENTIONED WARM
FRONTAL PASSAGE WILL ALLOW TEMPERATURES TO PUSH THE MIDDLE AND
UPPER 80S IN MANY LOCALES BY LATE AFTERNOON...WHILE DEWPOINTS INCH
UP INTO THE UPPER 60S. DEFINED ASCENT AND MOISTURE TRANSPORT
EVIDENT IN WATER VAPOR ALONG THE NOSE OF A STRONG MID LEVEL WAVE
AND ASSOCIATED 700 MB SPEED MAX NOW WORKING INTO ILLINOIS. THIS
WOULD SEEMINGLY PROVIDE THE GREATEST OPPORTUNITY FOR AN EXPANDING
REGION OF CONVECTION TO FOCUS AS IT ENTERS A MORE PRISTINE
THERMODYNAMIC ENVIRONMENT EXISTING DOWNSTREAM THROUGHOUT LOWER
MICHIGAN. WORTH NOTING THAT AN ANALYSIS OF MOST RECENT HIRES MODEL
GUIDANCE SUGGEST A LAKE MICHIGAN DRIVEN LEE TROUGH/CONVERGENCE
AXIS COULD ALSO BE A CATALYST FOR CONVECTIVE GROWTH...WITH THIS
ACTIVITY THEN TENDING TO PROPAGATE EAST INTO THE GROWING
INSTABILITY BUBBLE. WHILE DEEP LAYER SHEAR REMAINS BELOW 30
KNOTS...THE BACKGROUND WIND PROFILE REMAINS SUFFICIENT TO SUSTAIN
ORGANIZED CONVECTION AND PROVIDE A RISK OF DAMAGING WINDS AND
LARGE HAIL AFTER 19Z.
&&
.AVIATION...ISSUED 718 AM EDT MON MAY 20 2013
//DISCUSSION...
DEEP RIDGING WILL MAINTAIN PREDOMINANTLY VFR CONDITIONS AND LIGHT
WINDS INTO AT LEAST EARLY THIS AFTERNOON. INCREASING LOW-LEVEL
MOISTURE WILL POSE A SLIGHT RISK OF MVFR FOG BETWEEN THROUGH
15Z...MAINLY AT THE METRO AIRPORTS. BY LATE THIS MORNING...DIURNAL
MIXING WILL CONTRIBUTE TO SE WINDS GUSTING TO 20 KTS ALONG WITH A
SCT CU FIELD DEVELOPING AROUND 4KFT AGL. CIGS WILL GRADUALLY EVOLVE
TOWARD A BROKEN COVERAGE IN THE 4-5KFT RANGE BY MID/LATE AFTERNOON
AS SHOWERS & TSTORMS APPROACH THE AREA. CONFIDENCE IN TSTORM IS IN
THE MEDIUM RANGE...AND HIGHLY DEPENDENT ON INSTABILITY AND A TRIGGER
MECHANISM DURING THE LATE AFTERNOON AND EARLY EVENING HOURS. EVEN IF
THUNDERSTORMS DEVELOP...CONFIDENCE IS STILL LOW WITH REGARD TO THE
POTENTIAL FOR TSRA TO IMPACT ANY ONE LOCATION. WITH THIS IN
MIND...FEEL THAT THE CONTINUATION OF A PROB30 FOR TSRA AT ALL
LOCATIONS BEST REPRESENTS CONFIDENCE LEVEL. SHOWERS AND EMBEDDED
THUNDERSTORMS ARE EXPECTED TO CONTINUE INTO THE OVERNIGHT
HOURS...HOWEVER THUNDER COVERAGE WILL BE EVEN LOWER THAN LATE THIS
AFTERNOON AND THIS EVENING.
//DTW THRESHOLD THREATS...
* MEDIUM CONFIDENCE IN CEILINGS BELOW 5KFT AFTER 21Z.
* LOW CONFIDENCE THAT A THUNDERSTORM WILL IMPACT KDTW AIRSPACE AFTER
21Z.
&&
.PREV DISCUSSION...ISSUED 351 AM EDT MON MAY 20 2013
SHORT TERM...TODAY AND TONIGHT
UPPER LEVEL RIDGE AXIS WILL BE IN PLACE ACROSS THE CENTRAL GREAT
LAKES THIS MORNING. HOWEVER A HEALTHY SURGE OF HIGHER THETA-E AIR IN
THE 925 TO 850 MB LEVEL AND SYSTEM RELATIVE ISENTROPIC LIFT AT 310K
WILL TRACK THROUGH MICHIGAN DURING THE EARLY MORNING HOURS WITH
SEVERAL LOCAL AND NWP MODELS GENERATING SHOWERS BETWEEN 09-15Z.
DESPITE THE LOW LEVEL LIFT...THE UPPER LEVEL RIDGING AND DRY AIR IN
PLACE ARE A CONCERN AS WELL AS THE THETA-E SURGE WEAKENING AS IT
MOVES THROUGH THE AREA. WITH THESE FACTORS IN MIND POPS IN THE LOW
CHANCY RANGE SEEM APPROPRIATE AS THE LOW LEVEL LIFT CANNOT BE
COMPLETELY DISCARDED. MUCAPE VALUES EARLY THIS MORNING WILL BE
AROUND 1000 J/KG...WARRANTING THE INCLUSION OF THUNDER WITH THE RAIN
SHOWERS. GIVEN THE ELEVATED NATURE OF THIS MORNINGS CONVECTION AND
WEAK WIND FIELD THROUGH THE SOUNDING...SEVERE WEATHER IS NOT
EXPECTED TO BE AN ISSUE WITH THE EARLY DEVELOPMENT IF IT
MATERIALIZES.
AFTER THIS INITIAL SURGE THERE WILL BE A QUIET PERIOD LATER THIS
MORNING AND INTO THE EARLY AFTERNOON HOURS WITH THE RIDGE AXIS STILL
OVER THE CENTRAL GREAT LAKES...ALLOWING HIGH TEMPERATURES TO GET
INTO THE MIDDLE TO UPPER 80S AWAY FROM THE GREAT LAKES AS 850 MB
TEMPERATURES RISE INTO THE MIDDLE TO UPPER TEENS.
LATER THIS AFTERNOON AND INTO THIS EVENING A PIECE OF SHORTWAVE
ENERGY TRACKS THROUGH THE CENTRAL GREAT LAKES WHILE THE
AFOREMENTIONED RIDGE SLIDES EAST TOWARDS THE EASTERN GREAT LAKES AND
THE 850 MB LOW LEVEL JET CRANKS TO AROUND 30 KNOTS WITH THE NOSE
POINTED TOWARDS SOUTHEAST MICHIGAN. MUCAPE VALUES DURING THIS PERIOD
HOVER AROUND 2000 J/KG WITH 0-6KM BULK SHEAR VALUES OF 20 TO 30
KNOTS. SLIGHT RISK FOR SEVERE WEATHER CONTINUES WITH THE SPC DAY ONE
OUTLOOK WITH THE MAIN CONVECTIVE MODE EXPECTED TO BE LINEAR
STRUCTURES WITH SUPERCELLS POSSIBLE GIVEN THE DIRECTIONAL TURNING IN
THE LOW LEVELS. DAMAGING WINDS AND LARGE HAIL ARE EXPECTED TO BE THE
MAIN THREAT...WITH SOME ISOLATED TORNADOES POSSIBLE IF CONVECTION
CAN FIRE EARLY ENOUGH AND TAKE ADVANTAGE OF THE BETTER INSTABILITY
AND LOW LEVEL SHEAR.
WITH ONGOING CONVECTION OVERNIGHT AND ABUNDANT CLOUD COVER IN THE
WARM SECTOR...OVERNIGHT LOWS ARE EXPECTED TO STAY IN THE 60S TONIGHT.
LONG TERM...TUESDAY THROUGH SUNDAY
ACTIVE WEATHER PATTERN OVER SE MI TUESDAY THROUGH WEDNESDAY NIGHT
WITH STRONG TO SEVERE STORMS POSSIBLE ON TUESDAY. SHOWERS WILL TAPER
OFF THURSDAY BEFORE A STRONG CANADIAN HIGH PRESSURE SYSTEM BUILDS
INTO THE REGION THROUGH THE HOLIDAY WEEKEND LEAVING US COOL AND DRY.
MODEL GUIDANCE IS IN FAIRLY GOOD AGREEMENT OVERALL WITH THE LARGE
SCALE PATTERN AND THE STACKED LOW PRESSURE SYSTEMS OVER THE NORTHERN
PLAINS. THIS DOES NOT LEAD TO A HIGH CONFIDENCE FORECAST THOUGH AS
PERIODS OF SHOWERS AND THUNDERSTORMS WILL BE FORCED BY SMALL SCALE
SHORTWAVES ROTATING AROUND THE PARENT UPPER LOW WHICH ARE DIFFICULT
TO TIME THIS FAR OUT.
TUESDAY...LOOKS LIKE MULTIPLE ROUNDS OF STORMS WILL PASS THROUGH SE
MI THIS DAY. FIRST WE MAY HAVE TO DEAL WITH A CONVECTIVE COMPLEX
LINGERING INTO THE MORNING HOURS FROM THE OVERNIGHT. MAY TRY TO
CLEAR OUT DURING THE EARLY AFTERNOON BEFORE A SHORTWAVE ROUNDING THE
BASE OF THE UPPER LEVEL TROUGH REACHES THE AREA. MEANWHILE A SFC LOW
PRESSURE CENTER LOOKS TO TRACK THROUGH NORTHERN MI. THE
AFTERNOON TIMING WILL BE FAVORABLE FOR STORMS TO DEVELOP WITH A
STRONG DIURNAL COMPONENT INCREASING LOW LEVEL LAPSE RATES. OTHER
FAVORABLE PARAMETERS ARE MUCAPE VALUES PEAKING AROUND 1500 J/KG...30
TO 40 KNOTS OF EFFECTIVE SHEAR...STRONG LOW/HIGH LEVEL LAPSE
RATES...SHOWALTER INDEX AROUND -1...AND UPPER LEVEL SUPPORT AS WELL
WITH THE JET INCHING CLOSER TO MID MI AND WEAKENING UPPER LEVEL
DIFFLUENCE. HIGH PWATS REACHING 1.6 INCHES WILL SUPPORT HEAVY
RAINFALL AS WELL. SPC HAS INCLUDED SE MI IN THE SLIGHT RISK AREA
WHICH SEEMS MORE THAN WARRANTED AT THIS TIME.
MODELS HAVE BEEN ADVERTISING ANOTHER LULL TUESDAY NIGHT FOR A COUPLE
RUNS NOW...INCLUDING THE MOST RECENT 00Z ECMWF...SO FEEL COMFORTABLE
WITH THE INHERITED CHANCE POPS.
BY WEDNESDAY...THE ENTIRE PATTERN BECOMES MUCH MORE PROGRESSIVE AS
OUR ONCE CUT OFF UPPER LOW BEGINS PHASING WITH NORTHERN STREAM
TROUGHING OVER ONTARIO. BY NOW THE SFC LOW HAS BEEN VERY SHEARED OUT
WITH SEVERAL NEW CENTERS TRYING TO FOR ALONG THE MAIN BAROCLINIC
ZONE. THE STRONGEST OF WHICH LOOKS TO FORM OVER THE CENTRAL
MISSISSIPPI VALLEY. SHOWERS AND THUNDERSTORMS WILL BE LIKELY ONCE
AGAIN AS THIS LOW LIFTS NE INTO THE REGION. ISENTROPIC ASCENT WILL
INCREASE OVER THE STATE DUE TO THE LOW RUNNING INTO WARM FRONT THAT
HAS BEEN DRAPED OVER NORTHERN MI THROUGH THE WEEK. THE TRIPLE POINT
WILL PASS NORTHEASTWARD SOMEWHERE CLOSE TO THE MI/OH BORDER IN THE
EVENING.
AFTER DEALING WITH SOME LINGERING SHOWERS ON THE BACKSIDE OF THE
SYSTEM...HIGH PRESSURE WILL DROP IN FROM CANADA PUTTING AN END TO
THE WET STRETCH OF WEATHER. IT WILL ALSO USHER COOLER TEMPS...IN THE
60S...BACK INTO THE GREAT LAKES. TROUGHING OVER BOTH COASTS WILL
HELP AMPLIFY THE RIDGE OVER THE CENTRAL CONUS THROUGH THE WEEKEND.
MARINE...
A LOW PRESSURE SYSTEM OVER THE NORTHERN PLAINS WILL DRIFT TOWARD THE
GREAT LAKES LAYING OUT A WARM FRONT ACROSS CENTRAL MI. THIS FRONT
WILL STALL OVER THE AREA THROUGH MIDWEEK AS THE LOW TRACKS ALONG IT.
WINDS SOUTH OF THE FRONT WILL REMAIN SOUTHERLY WHILE WINDS TO THE
NORTH WILL BACK TO THE EAST AND INCREASE SLIGHTLY. THIS WILL LEAD TO
HIGHER WAVES OVER NORTHERN LAKE HURON WHILE THE SOUTHERN
BASIN...LAKE ST CLAIR AND LAKE ERIE KEEP WAVES GENERALLY UNDER 2
FEET. THIS LOW WILL BRING SCATTERED THUNDERSTORMS TODAY THROUGH
THURSDAY. WINDS WILL SHIFT TO THE NORTH ACROSS ALL WATERS BY
THURSDAY MORNING...AS THE LOW AND TRAILING COLD FRONT PUSH OFF TO
THE EAST.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.
&&
$$
UPDATE.......MR
AVIATION.....KURIMSKI
SHORT TERM...KURIMSKI
LONG TERM....DRK
MARINE.......KURIMSKI
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
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