000
FXUS63 KDVN 212104
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
300 PM CST SAT NOV 21 2009
.SYNOPSIS...
RIDGE OF HIGH PRESSURE IS SLIDING OFF TO THE EAST TODAY...ALLOWING
PRESSURE TO FALL ACROSS THE AREA...WINDS TO PICK UP OUT OF THE
SOUTHEAST...AND TEMPERATURES TO WARM INTO THE LOW TO MID 50S FOR
MANY LOCATIONS ACROSS THE CWA TODAY. STRATUS AND FOG FROM THIS
MORNING HAS MIXED OUT TO SOME EXTENT...THOUGH IT IS NEARLY INTACT
ACROSS PORTIONS OF NORTHERN IOWA AND SOUTHWEST WISCONSIN...AND WE
HAVE PATCHED OF IT EXTENDING DOWN INTO OUR NORTHEAST IOWA COUNTIES.
ALOFT THERE IS AN AMAZING POCKET OF WARM AIR AHEAD OF OUR NEXT UPPER
LEVEL TROUGH...WHICH IS MOVING OUT OF THE ROCKIES AT THIS TIME. AT
850MB WE HAVE AN AREA OF +12 TO +14 AIR OVER THE NORTHERN HIGH
PLAINS...AND THEY ARE INTO THE 50S AND EVEN LOW 60S AT THE SURFACE
TODAY AS A RESULT. THERE IS ALSO A FAIRLY DECENT TROUGH IN THE LEE
OF THE ROCKIES TODAY...AND WHILE THERE IS NO TEMPERATURE DIFFERENCE
ACROSS IT NOW...THAT IS PARTIALLY DUE TO DOWNSLOPING BEHIND IT. THE
GULF IS ALREADY OPEN...AS INDICATED BY A NARROW PLUME OF MOISTURE
WITH 850MB DEWPOINTS OF +5 OR HIGHER EXTENDING UP INTO OKLAHOMA.
THIS WAS GENERATED BY THE CUT OFF SOUTHERN STREAM UPPER LOW IN THAT
AREA. ..LE..
&&
.SHORT TERM...TONIGHT AND SUNDAY...
MAIN FORECAST IS FOR CLOUDS TONIGHT AND SUNDAY...WITH STRATUS AND
FOG OF PARTICULAR CONCERN. SURFACE DEWPOINTS ADVECTING INTO THE
AREA IN THE MID AND UPPER 40S INDICATES THAT OUR DEWPOINTS SHOULD
RISE FOR THE NEXT 6-12 HOURS...BUT THEN DROP OFF AGAIN TOWARDS
MORNING AND SUNDAY AS THE SLIGHTLY DRIER POCKET OVER SOUTHERN MO
MOVES IN. WE ARE ALSO SEEING CONVERGENCE AND POOLING TO OUR WEST
AHEAD OF THE TROUGH THAT IS SHOULD DEVELOP INTO A COLD FRONT
TONIGHT...AND THIS SHOULD ALSO ACT TO DRY OUR OUR DEWPOINTS LATE
TONIGHT AND SUNDAY. THESE DEWPOINT ISSUES WILL HAVE AN EFFECT ON
OUR AREA IN TEMPERATURE AND FOG DEVELOPMENT. EXPECT THAT A NEW AREA
OF STRATUS...ALREADY IN EVIDENCE OVER EASTERN KANSAS AND NEBRASKA
WILL ADVECT TOWARDS THE AREA TONIGHT...AND AHEAD OF IT WE SHOULD GET
SOME FOG DEVELOPMENT LATER TONIGHT AS TEMPERATURES DROP IN THE CLEAR
AIR WITH THE DEWPOINTS STILL RELATIVELY HIGH. TOUGH TO SAY...AS
MODELS ARE NOT HANDLING THIS WELL RIGHT NOW...BUT I CURRENTLY EXPECT
THE STRATUS BACK IN HERE SOMEWHERE AROUND MIDNIGHT OR SHORTLY
THEREAFTER. WE MAY GET SOME DRIZZLE WHERE THE STRATUS MOVES
IN...ESPECIALLY IF WE ALREADY HAD SOME FOG DEVELOPMENT BEFORE IT
MOVED IN. OUR NORTHEAST IS AT RISK OF DENSE FOG AGAIN TONIGHT AS
THEY SHOULD STAY CLEAR THE LONGEST AND GET THE COLDEST. SUNDAY WE
SHOULD GRADUALLY MIX OUT THE STRATUS LIKE WE HAVE TODAY...LEAVING US
WITH SOME SCT-BKN STRATOCU BY AFTERNOON. WARM AIR ADVECTION SHOULD
BRING US UP INTO THE MID-UPPER 50S IF NOT NEAR 60 AS IS CURRENTLY
HAPPENING OVER SOUTHERN MO. ..LE..
.LONG TERM...
SUNDAY NIGHT THROUGH MONDAY NIGHT...LIGHT SOUTHEASTERLY LLVL FLOW
BACK FROM RIDGE CENTER SHOULD KEEP LOW STRATUS AND MUCH OF ANY CHC
OF LIGHT PRECIP OFF TO THE WEST OF THE DVN CWA SUNDAY NIGHT...WITH
JUST VARYING LAYERS OF AC AND CI. ANY BREAKS IN THESE HIGHER DECKS
ALONG WITH A DECREASE IN THE SFC WINDS COULD MEAN AREAS OF FOG AGAIN
BUT WILL LEAVE OUT MENTION FOR NOW. EXPECT WIDESPREAD LOWS IN THE
UPPER 30S TO LOWER 40S AS LONG AS MOST OF THE HIGH CLOUDS MAINTAIN.
12Z RUN SHORT RANGE MODELS GENERALLY AGREE THAT AS THE NEXT LARGE
PIECE OF PACIFIC WAVE ENERGY DIGS INLAND ACRS THE ROCKIES AND
NORTHERN PLAINS THIS PERIOD...SPRAWLING SOUTHWEST MEAN STEERING FLOW
WILL ENGULF MUCH OF THE MID AND UPPER LEVEL MS RVR VALLEYS INTO MON
EVENING. MONDAY MAY REMAIN MOSTLY CLOUDY WITH CONTINUING BOUTS OF AC
AND CI...BUT LLVL SOUTHEASTERLY RETURN FLOW WILL ENSURE ANOTHER ABOVE
NORMAL TEMP DAY WITH SOME AREAS LOCALLY POSSIBLY STRIVING UP INTO THE
UPPER 50S WITH AT LEAST SOME TEMPORARY INSOLATION. AS LOW TO MID
LEVEL CYCLOGENESIS REVS UP ACRS THE CENTRAL PLAINS MON NIGHT IN
RESPONSE TO THE APPROACHING STRONG WAVE...THE INITIAL ARRIVAL OF
THE FIRST WAVE OF LIFT AND ASSOCIATED PRECIP INTO THE WESTERN CWA
DEPENDENT OF COURSE ON ADEQUATE LLVL SATURATION. THE 12Z RUN GFS
CONTINUES TO BE THE MOST BULLISH ON LLVL MOISTURE RETURN AND COLUMN
SATURATION ENOUGH FOR A QUARTER INCH OF RAIN INTO THE WESTERN
THIRD OF THE CWA BY 12Z TUE...WHILE THE NAM AND UKMET ARE MAINLY
DRY THROUGH THE PERIOD. THE NEW 12Z RUN ECMWF HAS BECOME MORE
PROGRESSIVE WITH THE APPROACH OF THE DEVELOPING CUT-OFF LOW COMPLEX
WITH THE FEATURE INTO SOUTHWEST IA BY TUE MORNING WHICH IS CURIOUS AS
IT STILL ADVERTISES A NEAR VERTICALLY STACKED SYSTEM WHICH SHOULD BE
SLOWER LIKE ITS EARLIER 00Z RUN. WILL KEEP CHC POPS ACRS THE WESTERN
2/3S ESPECIALLY AFTER 06Z TUE BUT THINK WITH THE INCREASING EAST-
SOUTHEAST LLVL FLOW OF A DRIER AIRMASS SOURCE...THE UKMET AND NAM ARE
ON TO SOMETHING WITH THEIR DELAY OF THE ONSET OF PRECIP AT THE SFC
ESPECIALLY IN AREAS ALONG AND EAST OF THE MS RVR. IF SFC DPTS
INCREASE MON NIGHT LOW TEMPS WILL HAVE A TOUGH TIME DIPPING BELOW THE
LOWER 40S.
IN THE EXTENDED/TUE-SAT/...MAIN CHALLENGE IN THE LONG TERM CONTINUES
TO BE HOW THE CUT-OFF LOW PRESSURE COMPLEX IMPACTS THE MID WEEK AND
HOLIDAY PERIOD. INTERESTING HOW THAT IN GENERAL THE 12Z MEDIUM
RANGE MODEL RUNS HAVE TRENDED MORE PROGRESSIVE WITH A CLOSED AND
NEAR VERTICALLY STACKED LOW PRESSURE SYSTEM THROUGH THE REGION TUE
INTO WED. THIS WOULD SUGGEST THAT LIKELY POPS WARRANTED CWA-WIDE ON
TUE FOR THE MAIN SURGE OF PRE-SYSTEM LIFT UTILIZING MOIST CONVEYOR...
BUT A WANE IN THE ACTION FROM THE SOUTHWEST-TO-NORTHEAST TUE
AFTERNOON WITH THE ARRIVAL OF IN-WRAPPING LOW TO MID LEVEL DRY SLOT
AND COLD CONVEYOR. DEPENDING ON THE MODEL...THE COLD CONVEYOR EVEN
SWITCHES THE THERMAL PROFILE INTO A RAIN/SNOW MIX OR EVEN ALL SNOW
FROM THE SAME DIRECTION/SW TO NE/ DURING THE AFTERNOON AND TUE
EVENING. IT/S JUST HOW MUCH PRECIP IS LEFT IN THE CWA FOR THIS
COOLING TO INTERACT WITH ESPECIALLY SOUTH OF I80...IF INDEED
THIS NEW QUICKER TIMING IS EVEN CORRECT. FOR NOW WILL UP THE POPS TO
LIKELY CWA-WIDE TUE BUT KEEP PRECIP ALL LIQUID THROUGH 00Z WED.
WILL GO WITH A MIX ACRS THE WESTERN THIRD AFTER 00Z WED MORE FOR A
WRAP AROUND PRECIP SCENARIO INTO THE COLD CORE LIKE THE CANADIAN
GEM IS SUGGESTING...WHILE LINGERING LIGHT RAIN OR DRIZZLE EXITS OUT
OF THE FAR EAST. FURTHER SHIFTS MAY HAVE TO END PRECIP TEMPORARILY
LATER TUE AFTERNOON AND THEN WALK IN STRAIGHT SNOW SHOWERS OR
FLURRIES TUE NIGHT AND WED IN WRAP AROUND INTO COLDER AIR.
AS THE MAIN CYCLONE CONTINUES TO BOMB OVER THE GRT LKS WED INTO
THU...THE NEW 12Z ECMWF HAS SIDED WITH THE THE 12Z GFS IN SUGGESTING
A SECONDARY LOW TO DROP DOWN TO THE WEST OF THE MAIN SYSTEM AND
INTERACT WITH IT SOME ALMOST FUJIWARA-LIKE. THIS SYSTEM WOULD BRING
BANDED SWATHS OF MAINLY SNOW UNDER IT WED NIGHT ACRS AT LEAST THE
NORTHERN 2/3S OF THE DVN CWA WITH SOME LIGHT ACCUMULATIONS POSSIBLE.
THE UKMET AND CANADIAN GEM DO NOT HAVE THIS SECONDARY SYSTEM AND JUST
ADVERTISE TIGHT CYCLONIC FLOW WITH EMBEDDED FLURRIES OR LIGHT SNOW
SHOWERS OF NO CONSEQUENCE WED NIGHT INTO TURKEY DAY. RIGHT NOW DO NOT
TRUST THE GFS AND EURO WITH THIS SECONDARY SYSTEM AND WILL JUST
ADVERTISE LIGHT SNOW SHOWERS OR FLURRIES WED NIGHT INTO THURSDAY BUT
TREND DOWN TEMPS. THURSDAY COULD BE A COLD BLUSTERY RAW DAY WITH
HIGHS ONLY IN THE 30S...FLURRIES AND WINDS GUSTING OVER 30 MPH.
RIDGING AND THERMAL MODERATION LOOK TO FOLLOW IN BEHIND THE EXITING
GRT LKS COLD CORE CYCLONE FOR THE START OF NEXT WEEKEND. ..12..
&&
.AVIATION...
MAIN QUESTION IS FOR FOG AND STRATUS DEVELOPMENT TONIGHT. EXPECT
STRATUS TO MOVE IN AND LOWER TO AROUND 15-25 HFT LATE THIS EVENING
AND OVERNIGHT. CIGS SHOULD BE LOWEST WEST...AND HIGHEST EAST. KMLI
AND KBRL WILL BE NEAR THE EDGES OF THIS STRATUS...BUT SHOULD SEE AT
LEAST A SHORT PERIOD OF IT. FOG DEVELOPMENT NEAR THE EDGES OF THE
STRATUS AND TO THE EAST MAY AGAIN BE DENSE...BUT WE SHOULD SEE
VISIBILITIES 1-2SM UNDER THE STRATUS LIKE WE HAD THIS MORNING.
BURN-OFF IN THE MORNING SHOULD OCCUR SOMETIME BETWEEN 16-20Z...WITH
SOME LOW CIGS REMAINING AT KCID AND KDBQ A FEW MORE HOURS.
..LE..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
LE/12
000
FXUS63 KDVN 211635
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1035 AM CST SAT NOV 21 2009
.UPDATE...
FOG HAS FINALLY DISSIPATED...WITH VISIBILITIES ABOVE A QUARTER
MILE AT ALL BUT A FEW LOCATIONS. THUS...ALLOWED FOG ADVISORY TO
EXPIRE BACK AT 10 AM. THE STRATUS DECK WITH CIGS AROUND 25HFT OVER
MAINLY THE IOWA COUNTIES IS GOING TO BE TOUGHER. LOOKING AT THIS
MORNINGS SOUNDING...IT IS GOING TO TAKE GETTING ABOVE THE MID 40S
WITH SOME MIXING AND WINDS TO GET RID OF THAT STRATUS
DECK...THOUGH IT DOES HELP THAT THE 925MB FLOW SLOWLY STRENGTHENS
THROUGH THE DAY...AND THIS SHOULD HELP TO AT LEAST BODILY SHOVE
THE STRATUS DECK TO THE NORTH. THE NEXT CLOUD DECK OF CONCERN THIS
MORNING IS THE SLIGHTLY HIGHER STRATUS OOZING NORTH OUT OF
MISSOURI. FOR THIS DECK HAVE RELIED A LITTLE MORE ON THE
MODELS...WHICH SLOWLY BRING IT INTO OUR SOUTH THIS
AFTERNOON...WHICH IS SUPPORTED BY A DISTANCE TIME TRACKING ON THE
SATELLITE IMAGERY.
&&
.AVIATION...
025HFT STRATUS DECK EXPECTED TO BEGIN TO LIFT AND THIN THROUGH THE
EARLY AFTERNOON HOURS...AND MAY DISSIPATE COMPLETELY BY 20-21Z.
WILL WATCH TRENDS CAREFULLY TO SEE IF WE ARE GETTING MUCH MIXING
TO BE ABLE TO DISSIPATE THESE CLOUDS.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
LE
000
FXUS63 KDVN 210820
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
220 AM CST SAT NOV 21 2009
.SYNOPSIS...
HIGH PRESSURE RIDGE OVER THE REGION WITH CLEAR SKIES...CALM WINDS
AND TEMP/DEWPOINT SPREADS VERY CLOSE. RADIATIONAL FOG/STRATUS
INCREASING OVER THE CWA. WARM AIR ADVECTION RETURNING TO THE PLAINS
ON THE BACKSIDE OF THE HIGH PRODUCING VEIL OF HIGH LEVEL CLOUDS FROM
NEB TO ND. ..HAASE..
&&
.SHORT TERM...TODAY AND TONIGHT...
FORECAST FOCUS IS THE FOG THIS MORNING THEN WARM ADVECTION CLOUDS
TONIGHT...AND ITS IMPACT ON TEMPERATURES. WILL CONTINUE WITH DENSE
FOG ADVISORY UNTIL 16Z OR 10 AM THIS MORNING. FOG PRODUCT SHOWS
FOG/STRATUS INCREASING OVER THE CWA WITH SEVERAL LOCATIONS IN
EASTERN IA ALREADY DOWN TO 1/4 MILE OR LESS. WITH CLEAR SKIES...
CALM WINDS AND TEMP/DEWPOINTS SPREAD VERY CLOSE DENSE FOG SHOULD BE
WIDESPREAD ACROSS THE CWA BEFORE SUNRISE. AFTER THE FOG DISSIPATES
AROUND MID MORNING EXPECT PLENTY OF SUNSHINE TO BOOST TEMPS INTO THE
50S... SOMEWHAT SIMILAR TO YESTERDAY. BELIEVE MET/MAV GUIDANCE MAY
BE A TAD TOO HIGH CONSIDERING THE FOGGY START TO THE DAY.
CLOUDS SHOULD BE ON THE INCREASE TONIGHT AS WARM AIR ADVECTION
SPREADS INTO THE REGION FROM THE WEST. ECMWF/GFS/GEM BRING LIGHT QPF
INTO OUR NW CWA LATE TONIGHT. THE UKMET/NAM ARE DRY SO THE END
RESULT IS I WILL MAINTAIN THE PATCHY DRIZZLE. WITH THE CLOUD COVER
TEMPS WILL BE WARMER...WITH MUCH OF THE CWA HAVING MIN TEMPS NEAR
TO ABOVE 40.
..HAASE..
.LONG TERM...SUNDAY THROUGH FRIDAY...
THE LONG TERM ONCE AGAIN WILL FOCUS ITS ATTENTION ON THE STORM WHICH
CONTINUES TO BE FORECAST FOR THE PERIODS SURROUNDING TUESDAY.
TONIGHT...ALL MODELS HAVE SLOWED THE SYSTEM SLIGHTLY...AND
STRENGTHENED IT AS WELL. OTHER THAN THAT...THE TENDENCIES OF THE GFS
BEING FASTEST AND WEAKEST...WITH THE ECMWF SLOWER...AND THE UKMET
STRONGEST AND SLOWEST ARE HOLDING TRUE ONCE AGAIN. ALL HAVE SHIFTED
SLIGHTLY SOUTH...WITH THE UKMET ONCE AGAIN THE MOST SOUTHERN...AND
THE GFS THE FARTHEST NORTH. THIS MODEL SPREAD AT 00Z TUESDAY MSLP
FORECASTS HAS THE GFS IN SOUTHWEST MN...EC IN CENTRAL KS...AND THE
UKMET IN SOUTHWEST OK. THAT IS A PRETTY WIDE SPREAD IN A 72 HOUR
FORECAST PERIOD. OUR FORECAST WILL CONTINUE TO REFLECT A BLEND OF
THE EC AND UK RUNS...SLOWER AND STRONGER WHICH MATCHES THE TRENDS OF
OTHER MODELS.
PRIOR TO THE STORM...WARM ADVECTION CONTINUES SUNDAY AND
MONDAY...WITH FORCING REMAINING MAINLY WEST OF THE CWA. THE
QUESTIONS FOR OUR AREA WILL BE CLOUD COVER AND ANY BRUSHING GLANCE
OF PCPN CHANCES. OTHER THAN THE GFS...MODELS SHOW THE FORCING TO
REMAIN WELL WEST...AND WILL LIMIT SLIGHT CHANCE POPS AND DRIZZLE
THREATS TO THE NORTHWESTERN CWA SUNDAY AND MONDAY. TEMPERATURES
CONTINUE TO LOOK MILD SUNDAY THROUGH MONDAY...WITH SOUTHERLY WINDS
CONTINUING TO PUMP INCREASING MOISTURE INTO THE REGION...AND KEEPING
THE BOUNDARY LAYER MIXED AND MILD. THIS ONCE AGAIN SUPPORTS
WIDESPREAD LOWER TO MID 50S SUNDAY AND MONDAY...ESPECIALLY IN THE
SOUTHEAST 2/3RDS WHERE DRY CONDITIONS ARE A STRONG BET. SUNDAY NIGHT
AND MONDAY NIGHT...WE SHOULD REMAIN MIXED AS WINDS STAY UP ABOVE 8
KTS...POSSIBLY HIGHER...THIS SHOULD KEEP LOWS FROM DIPPING MUCH
LOWER THAN THE LOWER 40S. WITH THE SLOWER SOLUTIONS PREFERRED...I
RAISED TUESDAYS HIGHS UP AS FEW DEGREES AS WELL SINCE COLD ADVECTION
LOOKS TO BE DELAYED UNTIL TUESDAY NIGHT. POPS HAVE BEEN BROUGHT UP
TO HIGH CHANCE TUESDAY AND MODERATE CHANCE TUESDAY NIGHT.
A TRANSITION TO A MIXED RAIN AND SNOW OR ALL SNOW IS STILL
POSSIBLE...BUT THESE DETAILS ARE OF LITTLE CONFIDENCE AT THIS
TIME...THUS OUR LOW POPS FOR A MIX WILL BE MAINTAINED INTO WEDNESDAY
NIGHT. FURTHER OUT...THE TREND TOWARD RAPID MODIFICATION HAS BEEN
MAINTAINED ON THE ECMWF RUN...AND SIMILAR TRENDS ARE SHOWN FOR LATE
WEEK IN THE GFS. NO CHANGES MADE...BUT A WARMUP LOOKS POSSIBLE.
...ERVIN...
&&
.AVIATION...
WIDESPREAD DENSE FOG WITH IFR/LIFR CONDITIONS THROUGH 16Z THEN RAPID
IMPROVMENT TO VFR CONDITIONS THEREAFTER. MVFR CIGS DEVELOP THIS
EVENING AND CONTINUE OVERNIGHT...ESPECIALLY FOR KCID/KDBQ. BELIEVE
THAT KMLI/KBRL WILL HAVE CIGS ABOVE 3K FT BUT THIS WILL NEED TO BE
MONITORED FOR POTENTIAL FOR MVFR CIGS.
..HAASE..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR BENTON-
BUCHANAN-CEDAR-CLINTON-DELAWARE-DES MOINES-DUBUQUE-HENRY IA-
IOWA-JACKSON-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE-LINN-LOUISA-
MUSCATINE-SCOTT-VAN BUREN-WASHINGTON.
IL...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR BUREAU-
CARROLL-HANCOCK-HENDERSON-HENRY IL-JO DAVIESS-MCDONOUGH-
MERCER-PUTNAM-ROCK ISLAND-STEPHENSON-WARREN-WHITESIDE.
MO...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR CLARK-
SCOTLAND.
&&
$$
HAASE/ERVIN
000
FXUS63 KDVN 202051
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
250 PM CST FRI NOV 20 2009
.SYNOPSIS...
12Z UA ANALYSIS SHOWS THE VERTICALLY STACKED UPPER LOW HAS MOVED
INTO CANADA WHILE A WEAK UPPER LEVEL RIDGE IS OVER THE WESTERN GREAT
LAKES. A WEAK TROF IN THE PLAINS WAS ASSOCIATED WITH SOME CI/CS PER
SATELLITE. SATELLITE TRENDS THROUGH MID DAY SHOW LOW LEVEL SC HAS
DEVELOPED ACROSS SOUTHERN IOWA/NORTHERN MISSOURI WHERE THE THICKEST
FOG WAS AT SUNRISE. 18Z SFC ANALYSIS HAS WEAK HIGH PRESSURE FROM THE
OHIO INTO THE MID MISSISSIPPI VALLEY AND ACROSS THE PLAINS. DEW
POINTS WERE GENERALLY IN THE LOW TO MID 40S WITH 30S AND 20S ACROSS
THE CENTRAL AND NORTHERN PLAINS.
&&
.SHORT TERM...TONIGHT AND SATURDAY...
FOG DEVELOPMENT IS THE MAIN QUESTION OVER THE NEXT 36 HRS. SEVERAL
FACTORS POINT TO FOG LATE TONIGHT/SATURDAY MORNING. HOWEVER...THE
SAME FACTORS WERE THERE TWO DAYS AGO AND NO FOG OCCURRED. DENSE FOG
THAT DEVELOPED IN WESTERN IA DID NOT FULLY CLEAR UNTIL NEARLY 18Z
TODAY. SO...THIS EVENING WILL BE QUIET. AFTER MIDNIGHT...WILL GO
WITH AREAS OF FOG ACROSS THE ENTIRE AREA AND CONTINUE IT THROUGH
SATURDAY MORNING. WILL HOLD OFF ON ANY HEADLINES FOR LATE
TONIGHT/SATURDAY MORNING ATTM. HOWEVER...THE POTENTIAL IS THERE FOR
WIDESPREAD DENSE FOG TO DEVELOP AND THE NEED FOR HEADLINES.
TEMPERATURES TONIGHT/SATURDAY WILL BE DEPENDENT ON ANY FOG
DEVELOPMENT. IF FOG GET THICK ENOUGH...MAX TEMPS FOR SATURDAY MAY BE
A LITTLE TOO WARM. ..08..
.LONG TERM...SATURDAY NIGHT THROUGH NEXT FRIDAY...
...SEASONABLY MILD TEMPERATURES...CONTINUED DRY CONDITIONS INTO
MONDAY...THEN MODERATE TO HEAVY PRECIPITATION TUE/WED WITH NEXT STORM
SYSTEM...
FORECAST INITIALIZATION GOOD OVER NORTH AMERICA...AMERICAN MODELS
STILL BELOW AVERAGE INITIALIZING PACIFIC UPSTREAM ENERGY RESULTING IN
STILL TOO FAST AND NORTH PROGRESSION OF NEXT WEEK/S SYSTEM. PRIMARY
GUIDANCE USED A BLEND OF NAM-WRF...GFS.... UKMET THROUGH SUNDAY...
THEN UKMET...GEM-NH...HI RES ECMWF MONDAY INTO FRIDAY.
FRIDAY NIGHT THROUGH SUNDAY NIGHT...ONLY MINOR CHANGES TO TEMPS.
PARTLY CLOUDY TO MOSTLY CLEAR SKIES AND GENERALLY LIGHT SE WINDS. IF
SKIES CLEAR ENOUGH...AGAIN AVAILABLE LOW LEVEL MOISTURE SUPPORTS
PATCHY TO AREAS OF MORNING FOG SUNDAY AND MONDAY AM FOR LATER SHIFTS
TO CONSIDER. TEMPERATURES UP TO ~5 DEGREES ABOVE NORMAL. RISK OF
SPRINKLES OR VERY LIGHT RAIN OR DRIZZLE...MAINLY SUNDAY AM FAR WEST
SECTIONS AS LOW LEVELS MOISTEN WITH MODERATE BL CONVERGENT FLOW BUT
FORCING IS LIMITED. HENCE KEPT...LOW CHANCE POPS TO COVER THIS.
MONDAY THROUGH THURSDAY...INDICATIONS OF CONSIDERABLE LOW CLOUDS...
FOG AND DRIZZLE AND LIGHT RAIN TO DEVELOP LATE MONDAY INTO TUESDAY
AHEAD OF NEXT STORM SYSTEM. LATER SHIFTS SHOULD REASSESS THIS TREND
AS LOCAL TOOLS SUGGEST THIS COULD BE SIGNIFICANT EVENT WITH MOIST LOW
LEVELS AND CONVERGENT BL FLOW. RAISED POPS LATE TUESDAY INTO
WEDNESDAY WITH STILL SOME QUESTION WHEN MAIN ENERGY PASSES. LATER
SHIFTS SHOULD BE ABLE TO RAISE TO LIKELY POPS NEXT 12 TO 24 HOURS.
RAIN TOTALS STILL SUGGEST WIDESPREAD .25 TO .5+ INCH AMOUNTS.
LINGERING QUESTION OF HOW QUICKLY COLD AIR WRAPS IN WEDNESDAY INTO
THURSDAY WITH A MIX OF SNOW AND RAIN. CLOSE EXAMINATION SUPPORTS
AREA TO SEE SOME SNOW WITH POSSIBLY MINOR ACCUMULATIONS IF BACKSIDE
SHORT WAVE DIVES ACROSS AREA. KEPT SLIGHT CHANCE POPS ATTM WITH A
MIX VERBIAGE UNTIL TIMING OF CAA AND ENERGY CONFIRMED. SOME ENERGY
PHASING ISSUES DO REMAIN BUT TRACK ASSURED FOR AREA TO SEE SEASONABLY
MODERATE TO LOCALLY HEAVY PRECIPITATION.
FRIDAY...BELOW NORMAL TEMPERATURES AND DRY AS CANADIAN HIGH PRESSURE
MOVES IN. LOW LEVEL THERMAL FIELDS SUPPORT COLDEST AIR OF THIS FALL
SEASON...MINS MAY NEED TRIMMING BY UP TO 5 DEGREES. ..NICHOLS..
&&
.AVIATION...
FOG/NO FOG ALONG WITH LIFR VSBYS/CIGS IS THE FCST QUESTION. LGT
WNDS...LIMITED MIXING AND CLRING SKIES ARE FAVORABLE FOR FG DVLPMNT.
MOST OF THESE FEATURES WERE PRESENT 2 DAYS AGO AND NO FG OCCURRED.
VFR CONDITIONS SHOULD BE SEEN THROUGH 03Z/21. AT SOME POINT BTWN
03Z-06Z PATCHY 3-5SM VSBYS WL DEVELOP. AFT 06Z/21 IF FG DEVELOPS
...VSBYS OF 3-5SM WL DEVELOP AND DROP QUICKLY. POTENTIAL THERE FOR
VLIFR VSBYS AND CIGS. HAVE OPTED TO GO WITH LIFR VSBYS/CIGS AT ALL
SITES IN THE 09Z-16Z TIME FRAME. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
08/NICHOLS
000
FXUS63 KDVN 200824
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
224 AM CST FRI NOV 20 2009
.SYNOPSIS...
LOW PRESSURE IN THE GREAT LAKES AREA MOVING NORTHEAST WITH HIGH
PRESSURE BUILDING INTO THE DVN CWA. SKIES HAVE CLEARED ACROSS MOST
OF THE NORTHERN CWA WHERE LOCALLY DENSE FOG HAS FORMED THE PAST
COUPLE OF HOURS. LOW CLOUDS STILL PREVAIL ACROSS THE SOUTHERN CWA.
UPPER LEVEL TROUGH EXTENDS FROM WESTERN MN TO WEST TX WITH HIGH
LEVEL CLOUDS AHEAD OF IT...AND CLEARING NOTED BEHIND THE TROUGH.
CURRENT TEMPS VARY FROM THE LOWER TO MID 30S IN CLEAR AREAS TO THE
MID 40S WHERE THE CLOUDS HANG ON. ..HAASE..
&&
.SHORT TERM...TODAY AND TONIGHT...
THE MAIN ISSUE WILL BE THE CURRENT FOG SITUATION WHERE SOME
LOCATIONS ACROSS OUR NORTH HAVE SEEN VISIBILITIES DROP TO NEAR
ZERO...AS SKIES CLEARED THERE EARLIER. WITH LIGHT SOUTHWEST WINDS
AND HIGH LEVEL CLOUDS STREAMING IN FROM THE WEST BELIEVE THIS WILL
PREVENT DENSE FOG FROM BECOMING WIDESPREAD. LOW CLOUDS OVER THE
SOUTHERN CWA SHOULD REMAIN INTO THE MORNING HOURS SO NOT REALLY
CONCERNED ABOUT FOG IN THAT AREA. WILL MENTION AREAS OF DENSE FOG
ACROSS THE NORTH AND PATCHY FOG SOUTH IN THE GRIDS FOR THIS MORNING.
WILL CONTINUE TO MONITOR SURFACE OBS AND WEB CAMS CONCERNING THE FOG
AND ISSUE AN ADVISORY IF NEEDED...BUT IN THE MEANTIME HAVE ISSUED A
SPECIAL WEATHER STATEMENT COVERING THIS SITUATION.
ONCE LOW CLOUDS AND FOG DISSIPATE THIS MORNING THE AFTERNOON SHOULD
SEE MOSTLY SUNNY SKIES. SOUTHWEST WINDS SHOULD PUSH TEMPS INTO THE
LOWER TO MID 50S...THE WARMEST WE HAVE SEEN IN ALMOST A WEEK.
MOSTLY CLEAR SKIES EXPECTED TONIGHT AS UPPER LEVEL TROUGH PUSHES OFF
TO THE EAST...WITH MIN TEMPS IN THE 30S.
..HAASE..
.LONG TERM...SATURDAY THROUGH THURSDAY...
THE LONG TERM BEGINS RELATIVELY QUIET UNDER A PERSISTENT WARM
ADVECTIVE REGIME...THEN ATTENTION TURNS EARLY IN THE WEEK TO A
TRANSITION TOWARD A ENERGETIC TROF IN THE MIDWEST. THIS TROF WILL
PROVIDE A THREAT FOR RAIN INITIALLY...BUT MAY ALSO BRING SNOW TO
PORTIONS OF THE AREA. MODELS CONTINUE TO OFFER VARYING SOLUTIONS OF
THE TRACK OF THE INITIAL SURFACE CYCLONE...WITH THE UKMET AND ECMWF
OFFERING MORE OF A SOUTHERLY TRACK...WHICH IS PERFERRED AT THIS
TIME. THE GFS AND NAM ARE MUCH FARTHER NORTH...BUT AT THIS POINT
OFFER SIMILAR SENSIBLE WEATHER FORECASTS...WITH MILD WITH RAIN
TURNING TOWARD COLDER THAN NORMAL WITH LOW CHANCES FOR RAIN OR SNOW.
DURING THE INITIAL WARM ADVECTIVE PATTERN...SATURDAY INTO SUNDAY
WEAK MID LEVEL LIFT COMBINED WITH A SHOT OF MOISTURE RETURN MAY
ALLOW FOR SOME LIGHT RAIN OR DRIZZLE NORTHWEST...BUT OTHERWISE
SHOULD BE MAINLY A PERIOD OF CLOUDS ROLLING THROUGH. THE MOISTURE
CAN BE FOUND ACROSS THE SOUTHERN STATES AT THIS TIME. SO DESPITE THE
CUT OFF GULF...THIS MOISTURE SHOULD RIDE UP...AND ONCE ITS
NORTH...SUNDAY MAY SEE CLEARING ONCE AGAIN IN THE AFTERNOON.
TEMPERATURES WILL BE FORECAST IN THE LOWER TO MID 50S...WHICH SHOWS
MIXING LEVELS TO AROUND 925MB OR SO SATURDAY AND SUNDAY. OVERNIGHT
LOWS WITH CLOUD COVER SHOULD HOLD IN THE UPPER 30S TO LOWER 40S SAT
AND SUNDAY NIGHT. MONDAY APPEARS TO BE A DRY DAY BASED ON SLOWER
SOLUTIONS OF MODELS OTHER THAN THE 00Z GFS. WILL KEEP A SLIGHT
CHANCE GOING FOR NOW...BUT THIS DAY APPEARS TO BE ANOTHER RATHER
PLEASANT DAY AHEAD OF THE POTENTIAL LOW PRESSURE SYSTEM TUESDAY.
TUESDAY INTO WEDNESDAY...THE POTENTIAL STORM TRACK NEAR THE
AREA...OR NORTHWEST ON THE CANADIAN AND GFS WOULD BRING RAINS...THEN
LIGHTER RAIN OR SNOW MIXED ON THE BACKSIDE AND DURING A PERIOD OF
COLD WEATHER INTO THURDAY. WITH NO ACCUMULATIONS EXPECTED AT THIS
TIME...WILL NOT MENTION THIS IN THE HWO YET.
...ERVIN...
&&
.AVIATION...
AREAS OF DENSE FOG WITH IFR/LIFR CONDS THIS MORNING ESPECIALLY NORTH
OF I-80. SOUTH OF I-80 CIGS 030-040 EXPECTED THIS MORNING. THIS
AFTERNOON VFR CONDITIONS WITH ONLY HIGH LEVEL CIRRUS CLOUDS AROUND.
VFR CONDITIONS TONIGHT WITH SKC. SOUTHWEST WINDS LESS THAN 10 KNOTS
TODAY BECOMING LIGHT SOUTHEAST TONIGHT.
..HAASE..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
HAASE/ERVIN
000
FXUS63 KDVN 192040
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
240 PM CST THU NOV 19 2009
.SYNOPSIS...
12Z UA ANALYSIS HAS THE VERTICALLY STACKED UPPER LOW ROUGHLY NEAR
KDBQ. UA ANALYSIS AND WATER VAPOR IMAGERY CONTINUE TO SHOW DISTINCT
VORT MAXES ROTATING AROUND THE UPPER LOW. IR AND FOG PRODUCT IMAGERY
ALONG WITH SFC OBSERVATIONS CONTINUE TO SHOW PLENTY OF LOW LEVEL
CLOUDS ACROSS THE MID MISSISSIPPI AND OHIO VALLEYS. 18Z SFC ANALYSIS
HAS THE LOW SOUTH OF KIMT WITH A TROF RUNNING FROM THE LOW INTO
NORTHERN MISSOURI. DEW POINTS WERE IN THE 40S ACROSS THE MID
MISSISSIPPI AND OHIO VALLEYS.
&&
.SHORT TERM...TONIGHT AND FRIDAY...
VERTICALLY STACKED SYSTEM WILL SLOWLY DRIFT NORTHEAST TONIGHT/FRIDAY
ENDING THE PRECIP THREAT FOR THE AREA. CURRENT RADAR TRENDS AND
CONDENSATION PRESSURE DEFICITS SUGGEST POSSIBLY SOME SPRINKLES EARLY
THIS EVENING OVER THE NORTHEAST/EAST PARTS OF THE CWFA. THE NEXT
QUESTION REVOLVES AROUND FOG POTENTIAL.
SATELLITE TRENDS SHOW BREAKS DEVELOPING IN THE CYCLONIC FLOW OF THE
UPPER SYSTEM. ANY BREAKS THAT DEVELOP...WHEN COMBINED WITH LIGHT
WINDS AND WET GROUND...SHOULD PROMOTE FOG DEVELOPMENT. A NEGATIVE IS
THAT THE RIDGE AXIS REMAINS WEST OF THE AREA. INTERESTINGLY...
GUIDANCE IS NOT OVERLY BULLISH ON FOG DEVELOPMENT. SO...WILL USE A
MIDDLE OF THE ROAD APPROACH REGARDING FOG. PREVIOUS FCST ALREADY HAD
FOG IN THE SOUTHERN THIRD TO 40 PERCENT OF THE CWFA. THEREFORE...
WILL KEEP THAT FOG AND EXTEND THE FOG UNTIL LATE FRIDAY MORNING
BASED ON WHAT HAPPENED IN CENTRAL IOWA THIS MORNING.
TEMPERATURES TONIGHT/FRIDAY WILL BE HIGHLY DEPENDENT ON CLOUD COVER
AND FOG DEVELOPMENT. TWEAKED MINS TONIGHT SLIGHTLY BUT CURRENT MAX
TEMPS FOR FRIDAY LOOKED OK.
..08..
.LONG TERM...FRIDAY NIGHT THROUGH NEXT THURSDAY...
...SLIGHTLY ABOVE NORMAL TEMPERATURES...QUIET...DRY CONDITIONS INTO
SUNDAY...THEN UNSETTLED WITH MODERATE TO STRONG STORM SYSTEM
EARLY TO MIDDLE NEXT WEEK...
FORECAST INITIALIZATION GOOD TO VERY GOOD OVER NORTH AMERICA...
POOR FOR GFS AND NAM-WRF IN PACIFIC. THIS RENDERS THEM USELESS
BEYOND DAY3. PRIMARY GUIDANCE USED IS UKMET...GEM-NH...HI RES
ECMWF.
FRIDAY NIGHT THROUGH SUNDAY NIGHT...LITTLE CHANGE MADE...DRY
WITH PARTLY CLOUDY TO MOSTLY CLEAR SKIES AND GENERALLY LIGHT WINDS.
SOME LOW LEVEL MOISTURE SUPPORTS RISK OF SOME PATCHY MORNING FOG
SATURDAY AND SUNDAY AM FOR LATER SHIFTS TO CONSIDER. TEMPERATURES TO
AVERAGE 2 TO 5 DEGREES ABOVE NORMAL. SE WINDS MAY ALLOW FOR NEED TO
RAISE MAX TEMPS ON SUNDAY IF GET ENOUGH SUNSHINE. LOW CHANCE POPS
LATE SUNDAY IN MAINLY NW AS WEAK FRONT APPROACHES.
MONDAY THROUGH THURSDAY...KEPT CHANCE POPS AS LARGE UNCERTAINTY
REMAINS WITH MODERATE STRENGTH...CLOSED UPPER LOW PHASING OVER
SOUTHERN PLAINS. INCORPORATING MODERATE STRENGTH PACIFIC DECADAL
OSCILLATION OR PDO AND MODERATE EL NINO...SUPPORTS A SOUTHERN US
CLOSED SYSTEM. THIS IS ONE REASON WHY GFS AND NAM-WRF ARE NOT
REASONABLE AS TOO FAR NORTH AND PROGRESSIVE. THESE TYPES OF SYSTEMS
ARE SEASONABLY WET WITH TRACK ONLY QUESTION OF HOW MUCH RISK OF SNOW
AS SYSTEM LIFTS NORTHEAST. VARIANCE OF NON-US MODEL RUNS SUPPORT THE
TIMING AND TRACK OF THIS SYSTEM SHOULD BE CLARIFIED FRIDAY. KEPT
TEMPS SLIGHTLY ABOVE NORMAL BUT LOCAL HEAVY RAIN TECHNIQUES STILL
SUGGEST WIDESPREAD .25 TO .5+ INCH TOTALS OF RAIN...POSSIBLY CHANGING
TO SNOW. LARGE SCALE FEATURES WITH ENERGY ON BACKSIDE DO SUPPORT
SOME SNOW IN COLD SECTOR AS SFC LOW MOVES NORTHEAST AND COLD AIR
DIVES IN. AGAIN...THE RISK OF ACCUMULATIONS SHOULD BE IDENTIFIED IN
NEXT 24 HOURS. LARGE SCALE DYNAMICS STILL SUGGEST MAIN ENERGY TO PASS
LATE TUESDAY INTO WEDNESDAY. ..NICHOLS..
&&
.AVIATION...
VERTICALLY STACKED SYSTEM TO SLOWLY DEPART TNGT/FRIDAY. WET GROUND
AND LIGHT WINDS ARE FAVORABLE FOR FG DEVELOPMENT IF BREAKS CONTINUE
TO DEVELOP IN THE CLDS. HOWEVER...GUIDANCE IS NOT OVERLY BULLISH ON
FG DEVELOPMENT. CIGS TO IMPROVE TO VFR BY 00Z/20 AND VFR CIGS/VSBYS
SHOULD BE SEEN THROUGH 06Z/20. AFT 06Z/20...3-5SM VSBYS TO DEVELOP
THAT MAY DROP TO 1-2SM JUST BEFORE/AFTER SUNRISE. CIGS TO DROP TO
AROUND 2KFT AFT 06Z/20 AND MAY DROP TO 1KFT JUST BEFORE/AFTER
SUNRISE IN ANY THICKER FG THAT DEVELOPS. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
08/NICHOLS
000
FXUS63 KDVN 190922 RRA
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
321 AM CST THU NOV 19 2009
.SYNOPSIS...
VERTICALLY STACKED UPPER LOW WAS CENTERED NEAR KMUT AT 08Z PER KDVN
WSR-88D AND WATER VAPOR IMAGERY. WAVES OF DZ/--RA CONTINUE ACROSS
REGION EARLY THIS AM AS SEVERAL VORT LOBES CONTINUE PINWHEELING
AROUND THE MAIN CIRCULATION. KDVN WSR-88D DOES SHOW NARROW BAND OF
HIGHER REFLECTIVITIES /BRIEF PD OF MOD RAIN/ LIFTING NNW ACROSS
PORTIONS OF NORTHERN HENRY CTY AND SOUTHERN WHITESIDE CTY ATTIM ON
EAST SIDE OF MAIN CIRCULATION AND AHEAD OF VORT LOBE MOVING E/NE
THROUGH SOUTHEAST IA...NORTHEAST MO AND WEST CENTRAL IL. ANOTHER VORT
LOBE WAS SEEN RETROGRADING THROUGH NORTHEAST IA. WATER VAPOR AND 00Z
SUBJECTIVE UPPER AIR ANALYSIS SHOW SPLIT FLOW ACROSS THE WESTERN CONUS
WITH VIGOROUS JET AND NORTHERN STREAM ENERGY PLOWING THROUGH THE
PAC NW INTO THE NORTHERN ROCKIES... WHILE SOUTHERN STREAM SHORTWAVE
TROUGH WAS DIVING THROUGH FAR SOUTHWEST U.S. ..MCCLURE..
&&
.SHORT TERM...TODAY AND TONIGHT...
VERTICALLY STACKED LOW... WHICH HAS MORE THAN WORN OUT ITS WELCOME..
TO FINALLY GET KICKED TO THE CURB... AS SYSTEM GETS SHUNTED EWD
INTO GREAT LAKES BY THIS EVE AHEAD OF SHORTWAVE ENERGY PROGRESSING
EWD THROUGH THE ROCKIES AND PLAINS. THEREFORE EXPECT BANDS OF
DZ/-RA TO SLOWLY DIMINISH FROM SOUTHWEST TO NORTHEAST TODAY. WHILE
PCPN TRENDS ARE OPTIMISTIC... CLEARING TRENDS AND POTENTIAL TO
SEE SUN TODAY NOT NEARLY SO. THE CLEARING LOOKS TO COME FROM THE
SOUTHWEST WITH DRY AIR ENTRAINMENT AND SUBSIDENCE IN WAKE OF LOW.
AWIPS DISTANCE/SPEED TOOL HOWEVER ONLY SHOWING BACK EDGE OF CLOUDS
OVER NORTHEAST KS INTO WESTERN MO MOVING AT 10 KTS OR SO... WHICH
PLACES CLEARING ON DOORSTEP OF FAR SOUTHWEST CWA TOWARD EVE.
WITH THIS IN MIND... WILL CONTINUE TO ADVERTISE LIMITED DIURNAL
SWING TODAY STAYING AT OR JUST BELOW COOL SIDE OF GUIDANCE ON MAXES.
TNGT... CLEARING LOOKS TO CONTINUE GRADUALLY ADVANCING NEWD... WITH
THE NORTHEAST COUNTIES LIKELY TO STAY CLOUDY MOST IF NOT ALL NIGHT.
HAVE NUDGED UP MINS 1-2 DEGS FAR NORTH STAYING AT OR ABOVE WARMEST
GUIDANCE... WHILE SIDED NEAR TO JUST BELOW COOLEST GUIDANCE SOUTH
WHERE LIGHT WINDS AND SKIES TO CLEAR EARLIEST. THIS WILL SET UP FOG
POTENTIAL OVRNGT SOUTH OF I-80 WITH BL COOLING AND RESIDUAL LOW LEVEL
MOISTURE FROM RECENT RAIN... AND HAVE ADDED MENTION TO FCST. IF
WINDS GO CALM FOR ANY LENGTH THEN COULD SEE SOME DENSE FOG FOR LATER
SHIFTS TO REVISIT.
.LONG TERM...FRIDAY THROUGH WEDNESDAY...
INITIAL FOCUS IS ON LINGERING LOW LEVEL MOISTURE AND ITS IMPACT ON
CLOUDS AND TEMPERATURES...THEN CHANCES FOR PRECIPITATION LATE
WEEKEND INTO NEXT WEEK AS UPPER PATTERN BECOMES MORE AMPLIFIED.
MID LEVEL SHORTWAVE CURRENTLY MOVING THROUGH THE NORTHERN ROCKIES
GLIDES OVER THE REGION LATE FRI WITH LITTLE MID LEVEL MOISTURE TO
WORK WITH AND WILL MAINTAIN DRY FORECAST. AT LOW LEVELS...WEAK RIDGE
EXTENDING NW OUT OF THE OHIO RIVER VALLEY HANGS ON THROUGH THE DAY.
LIGHT LOW LEVEL WINDS AND TRAPPED MOISTURE BELOW H9 UNDER WEAK
WARM ADVECTION DEVELOPING AROUND H8 WILL LIMIT MIXING AND POSSIBLY
KEEP LOW CLOUDS IN PLACE THROUGH MUCH OF THE DAY. HAVE THUS KEPT
HIGHS AT LOW END OF GUIDANCE RANGING FROM AROUND 50 NORTH TO LOWER
50S SOUTH.
ADVANCING LEE TROUGH AND RETREATING SURFACE RIDGE ALLOWS DEEPER
SOUTHERLY FLOW AND MOISTURE RETURN TO OVERSPREAD THE REGION FRI
NIGHT INTO SAT...INCREASING THE POTENTIAL FOR LOW CLOUDS OVER THE
AREA. THIS SHOULD SUPPRESS DIURNAL TEMPERATURE SWINGS AND HAVE
MINS IN UPPER 30S TO LOWER 40S WITH MAXES IN 50S...WHICH IS STILL
ABOVE CLIMO.
MODELS IN DECENT AGREEMENT WITH NEXT SHORTWAVE LATE SAT NIGHT INTO
SUNDAY AND HAVE LOW CHANCE POPS FOR RAIN IN MAINLY THE CENTRAL AND
WEST. BEYOND...STILL SIGNIFICANT DIFFERENCES IN EVOLUTION AND TIMING
OF NEXT STORM SYSTEM EARLY NEXT WEEK. AFTER STRAYING SIGNIFICANTLY
IN THE LAST 12Z RUN WITH A CUTOFF LOW HANGING BACK OVER THE
SW...SIMILAR TO THE LATEST GEM...THE 00Z ECMWF TRENDED BACK CLOSER
TO THE MORE CONSISTENT GFS DEPICTING THE NEXT WAVE DEEPENING INTO
CLOSED LOW IN THE N CENTRAL CONUS BY TUE...THEN SWEEPING EAST. THIS
WOULD ALLOW MUCH COLDER AIR TO SPILL BRIEFLY INTO THE AREA. THE GFS
IS THEN MORE PROGRESSIVE OUTLIER...SHUNTING THE INITIAL LOW EAST
WITH ANOTHER ON ITS HEALS WED. WITH STILL MUCH UNCERTAINTY...CHANCE
POPS FOR RAIN MON AND POSSIBLE RAIN/SNOW MIX BY TUE AFTERNOON AND
EVENING MAINTAINED FOR NOW. TEMPERATURES COOLING TO NEAR CLIMO EARLY
NEXT WEEK...MAY NEED TO BE FURTHER LOWERED...ESPECIALLY TOWARD MID
WEEK AS CONFIDENCE IN TIMING OF SYNOPTIC FEATURES INCREASES.
..SHEETS..
&&
.AVIATION...
VERTICALLY STACKED LOW OVER EASTERN IA WILL MOVE EWD INTO THE GREAT
LAKES BY THIS EVE. CONDITIONS EXPECTED TO GRADUALLY IMPROVE FROM
GENERALLY MVFR TO IFR CIGS/VSBYS WITH -RA/DZ... TO VFR BY THIS EVE.
LIGHT AND VARIABLE SFC WINDS TO BECOME SOUTHWESTERLY AT 4-8 KTS. SFC
RIDGE OF HIGH PRESSURE WILL SETTLE OVER SOUTHEAST IA LATE TNGT.
RESIDUAL LOW LEVEL MOISTURE...LIGHT WINDS AND CLEARING SKIES WILL
BRING THREAT OF FOG WITH IFR TO POSSIBLY LIFR VSBYS TO KBRL.
..MCCLURE..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
MCCLURE/SHEETS
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