[top]
000
FXUS63 KDMX 212048
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
348 PM CDT TUE MAY 21 2013
.SHORT TERM.../TONIGHT/
ISSUED AT 346 PM CDT TUE MAY 21 2013
STEEPING LOW-LEVEL LAPSE RATES DUE TO BOTH CAA IN THE 700 TO 850 MB
LAYER AND DIURNAL LATE MAY HEATING LED TO THE QUICK DEVELOPMENT OF A
STRATOCU DECK OVER MUCH OF IOWA THIS MORNING. THE CLOUDS WERE THICKEST
IN THE NORTHWEST...WHICH LIMITED DAYTIME HIGHS TO THE LOW TO MID
60S. DRIER AIR FILTERING IN FROM THE WEST WILL ALLOW LOW TEMPERATURE
READINGS TO FALL OFF INTO THE LOW 50S...THOUGH THESE COULD BE
COMPLICATED BY THE INCREASING CLOUDS OVERNIGHT.
THINNER CUMULUS OVER SOUTHERN AND EASTERN IOWA SHOULD LESSEN IN
COVERAGE BY SUNSET...BUT CLOUDS WILL BUILD BACK IN AS THE LOW SHIFTS
TO THE EAST ACROSS SOUTHERN MINNESOTA. CHANCES FOR PRECIP WILL
INCREASE AFTER 06Z ACROSS NORTHERN IOWA AS THE SURFACE LOW TRACKS
ACROSS THE REGION. WEAK ISENTROPIC LIFT ALONG THE 300 TO 310 K
SURFACES ON THE BACKSIDE OF THE LOW WILL BE THE MAIN DRIVING FORCE
FOR PRECIP. THIS PROCESS WAS REFLECTED WELL IN THE HIGH RES EAST
WRF-ARW MODEL AND USED THIS AS A BASE FOR POP CHANCES FOR THE
PERIOD. MID TO UPPER LEVEL VORT MAX MAY ALSO SPARK A FEW STRAY
SHOWERS OVER FAR NORTHERN IOWA CLOSE TO THE LOW CENTER DURING THE
EARLIER OVERNIGHT HOURS...BUT WAS NOT CONFIDENT ENOUGH TO MENTION IN
THE FORECAST WORDING.
.LONG TERM.../WEDNESDAY THROUGH TUESDAY/
ISSUED AT 346 PM CDT TUE MAY 21 2013
PATTERN LOOKS ACTIVE RIGHT INTO EARLY NEXT WEEK OUTSIDE OF BREAK
THURSDAY INTO FRIDAY. PERIOD SHOULD BEGIN ESSENTIALLY WITH
EXTRAPOLATION OF WHAT IS CURRENTLY ONGOING OVER MN AS IT DRIFTS
SOUTHWARD INTO WED. DEEPER FORCING MAINLY REMAINS FROM ERN MN
INTO WI...BUT MOISTURE IS FAIRLY DEEP WITH SOUNDINGS SHOWING
COLUMN SATURATING. THIS SHOULD AMOUNT TO SCATTERED SHOWERS AND
POSSIBLY A RUMBLE OF THUNDER OR TWO DURING THE DAY AND LINGERING
INTO TOMORROW NIGHT BEFORE EXITING BY DAYBREAK FRI. TEMPS SHOULD
BE FAIRLY COOL...HELD DOWN BY PLENTY OF CLOUDS...PRECIP AND COOLER
TEMPS BEHIND DEPARTING CYCLONIC FLOW.
UPPER LEVEL RIDGE WILL THEN ENTER THE MO VALLEY WITH FAIR WEATHER
INTO AT LEAST EARLY FRI. THETA-E ADVECTION THEN QUICKLY RETURNS FRI
NIGHT WHICH WILL LIKELY RESULT IN WEST TO EAST MCS DEVELOPMENT.
RIDGE CONTINUES TO WEAKEN INTO EARLY NEXT WEEK WHICH WILL RESULT IN
PROLONGED SOUTHWEST UPPER FLOW. GFS IS A LITTLE MORE BULLISH THAN
THE ECMWF WITH ECMWF SHOWING A STRONGER GREAT LAKES HIGH PRESENCE
AND WARM ADVECTION SHIFTED A BIT FARTHER WEST. RESULTANT PRECIP
FROM THIS PATTERN WOULD BE A STRING OF ELEVATED CONVECTIVE
COMPLEXES. SURFACE BASED POTENTIAL DOES NOT LOOK TOO GREAT WITH
LEE SIDE TROUGH STAYING TO OUR WEST AND ONLY SUBTLE WARM FRONTAL
INFLUENCES IN PROLONGED GENERALLY SOUTHEAST SURFACE FLOW. HOWEVER
MCSS COULD BE STRONGER BY THE WEEKEND WHEN ELEVATED INSTABILITY
INCREASES AND EVEN THE ECMWF NUDGES THIS MUCAPE EASTWARD INTO WEST
AND SOUTH IA. CERTAINLY NO SPECIFICS AT THIS POINT BUT HYDRO
SITUATION WILL NEED TO BE WATCHED AS MANY RIVER SITES IN THE
NORTHEAST HALF OF THE STATE ARE ALREADY AT THE 90TH FLOW
PERCENTILE OR HIGHER AND ANY APPRECIABLE RECOVERY PERIOD IS NOT FORESEEN.
&&
.AVIATION...21/18Z
ISSUED AT 1243 PM CDT TUE MAY 21 2013
WIDESPREAD STRATOCUMULUS WILL CONTINUE TO CIRCULATE AROUND A SLOW
MOVING UPPER LOW OVER MINNESOTA THROUGH WEDNESDAY. THERE HAS BEEN
A DIURNAL INCREASE IN CIG HEIGHT TO VFR LEVELS THROUGH THIS
MORNING...AND VFR CIGS AROUND 3500 TO 5000 FT WILL CONTINUE
THROUGH EARLY EVENING...WHEN DIURNALLY THEY WILL DROP BACK TO MVFR
LEVELS. IN ADDITION...COLDER AIR ARRIVING ALOFT WILL HELP DROP
CIGS TO THE 1000 TO 1800 FT LEVELS. VISIBILITIES SHOULD REMAIN
GOOD...THROUGH A FEW SHOWERS MAY IMPACT LOCATIONS NORTH OF
INTERSTATE 80 DURING THE DAY WEDNESDAY. WINDS WILL BE MAINLY WEST
TO SOUTHWEST TODAY AT 12 TO 20 KTS...AND NORTHWEST OVERNIGHT AND
WEDNESDAY...AROUND 10 KTS.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...SKOW
LONG TERM...SMALL
AVIATION...ERVIN/DVN
[top]
000
FXUS63 KDVN 212031
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
331 PM CDT TUE MAY 21 2013
.SYNOPSIS...
ISSUED AT 240 PM CDT TUE MAY 21 2013
A CLOSED H5 LOW WAS LOCATED OVER SOUTHEASTERN SOUTH DAKOTA AND
SOUTHWESTERN MINNESOTA EARLY THIS AFTERNOON. AT THE SURFACE
ELONGATED LOW PRESSURE EXTENDED FROM SOUTHEAST SOUTH DAKOTA INTO
WISCONSIN WITH TWO CIRCULATION CENTERS LOCATED ON THE WESTERN AND
EASTERN PORTIONS OF THE TROF. A WEAK COLD FRONT OVER EASTERN
IOWA/NORTHWEST ILLINOIS THIS AFTERNOON ORIGINATED IN THE WISCONSIN
LOW WHILE A SECONDARY FRONT WAS JUST ENTERING NORTHWEST IOWA.
ANOTHER...STRONGER...CLOSED H5 LOW WAS JUST MOVING INTO THE
PACIFIC NORTHWEST AND SHOULD ACT AS A KICKER TO DISLODGE THE MID
WEST SYSTEM.
&&
.SHORT TERM...(THIS EVENING THROUGH WEDNESDAY)
ISSUED AT 240 PM CDT TUE MAY 21 2013
THE SYSTEM OVER THE CENTRAL U.S. WILL STAY OVER MINNESOTA AND
SOUTH DAKOTA TONIGHT AND THEN DROP SOUTHEAST WEDNESDAY KEEPING THE
REGION IN COOL CYCLONIC FLOW THROUGH THE PERIOD.
WEAK CONVERGENCE ALONG THE MID MISSISSIPPI VALLEY COLD FRONT AND
MODEST CAPES AROUND 1000 J/KG WILL PROVIDE A CHANCE OF SOME
EVENING THUNDERSTORMS EAST OF THE MISSISSIPPI RIVER THIS EVENING. A
S/W OVER THE SOUTHERN PLAINS THIS AFTERNOON WILL LIFT NORTHEAST
TONIGHT SPREADING MORE SHOWERS INTO AREAS ALONG AND EAST OF THE
MISSISSIPPI RIVER LATE TONIGHT AND WEDNESDAY MORNING. WEDNESDAY
AFTERNOON...AS A WEAKENING SURFACE LOW MOVES SOUTHEAST THROUGH THE
REGION...WRAP AROUND SHOWERS WILL SPREAD OVER THE AREA WITH THE
BETTER CHANCES ALONG AND NORTH OF INTERSTATE 80. COOL AIR
ADVECTING IN TO THE REGION TONIGHT AND WEDNESDAY WILL BRING
TEMPERATURES IN THE 50S AND LOW 60S TONIGHT. WEDNESDAY WITH COOLER
AIR AND PLACE AND WIDESPREAD CLOUDS HIGHS WILL ONLY BE IN THE 60S
AND LOW 70S.
.LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY)
ISSUED AT 240 PM CDT TUE MAY 21 2013
WEDNESDAY NIGHT AND THURSDAY...SHOWERS WILL LOOK TO PIVOT AROUND
WESTERN FLANK OF WESTERN GRT LKS TROF WED NIGHT AN MAY BE MORE
PREVALENT ALONG AND NORTH OF I80 FROM 00Z-06Z...AND THEN CONTINUE
TO ROTATE SOUTH AND EAST INTO THU MORNING. FCST SOUNDINGS SUGGEST
DEEPER SATURATED SOUNDINGS WED EVENING WITH PW/S PUSHING OVER AN
INCH...BUT FORCING AND INSTABILITY MARGINAL TO MAKE THE MOST OF THOSE
PROFILES. MOST AREAS TO GET 2 TENTHS OF AN INCH OR LESS BY THU
MORNING. WILL NOT MENTION ANY THUNDER THU EVENING WITH LIMITED
INSTABILITY PROFILES. TOP-DOWN SATURATION LATE WED NIGHT INTO THU
MORNING MAY TREND SHOWERS INTO MORE OF A DRIZZLE REGIME AFTER 3 AM
CDT. A COOL DAMP NIGHT WITH LOWS IN THE LOWER 50S WITH SOME UPPER
40S POSSIBLE. SECONDARY SATELLITE VORT SPOKE MAY KEEP SHOWERS
FESTERING ACRS THE SOUTHEASTERN HALF OF THE FCST AREA THU MORNING
BEFORE THAT ACTIVITY MOVES OUT OR DECAYS BY AFTERNOON. HIGHS HELD IN
THE 60S LATEST 12Z RUN MODELS IN GOOD AGREEMENT IN ADVERTISING
SEASONABLY STRONG BACKDOOR CANADIAN SFC HIGH DUMPING DOWN THE WESTERN
GRT LKS LATE THU AND THU NIGHT...WITH ASSOCIATED COOL PUSH AND CLOUD
CLEAR OFF SETTING THE STAGE FOR A CHILLY NIGHT THU NIGHT. CURRENTLY
PROGGED AIR MASS ADVECTING IN COULD SUPPORT WIDESPREAD LOWS BY FRI
MORNING IN THE LOWER 40S TO UPPER 30S...EXCEPT FOR MID 40S IN THE
SOUTHWESTERN CWA.
FRIDAY AND SATURDAY...AFTER COOL START TO THE DAY...FRI LOOKS TO BE
MAINLY SUNNY UNTIL SOME HIGH CLOUDS SPILL IN FROM THE WEST OFF
GATHERING CONVECTION IN RETURN FLOW ACRS THE PLAINS. WARM AIR
RETURN FLOW ALOFT ESPECIALLY AROUND THE H85 MB LAYER COULD LIMIT
MIXING DEPTH AND KEEP FRI HIGHS HELD IN THE MID 60S EVEN WITH A LOT
OF INSOLATION. FRI NIGHT SOLUTIONS START TO DIVERGE BETWEEN THE 12Z
GFS...THE ECMWF...UKMET AND GEM. THE ECMWF CONTINUES TO BE LESS
AMPLIFIED WITH MID CONUS UPPER RIDGING...ALLOWING MCS DEVELOPMENT
ACRS THE CENTRAL PLAINS TO LEE OF WESTERN CONUS TROFFINESS TO RIDGE-
RIDE AND PROPAGATE EASTWARD ALONG H85 MB BOUNDARY ACRS PORTIONS OR
ALL OF THE DVN CWA LATER FRI NIGHT AND INTO SAT MORNING. THE NEW 12Z
ECMWF FAVORS HEAVIER ELEVATED CONVECTION FED ON H85 THTA-E PLUME ACRS
THE SOUTHERN HALF TO THIRD OF THE DVN CWA FRI NIGHT..WHERE AREAS
COULD GET UP TO AN INCH OF RAINFALL BY SAT MORNING. THIS IN CONTRAST
TO THE MORE AMPLIFIED RIDGE AND FURTHER WE AXIS PLACEMENT OF THE
12Z GFS...WHICH KEEPS FRI NIGHT AND SAT MORNING BASICALLY DRY UNTIL
ELEVATED PRECIP SYSTEM MOVES IN FROM THE WEST BY LATE SAT AFTERNOON.
THE GFS THEN SUGGESTS LLJ AND WARM MOIST CONVEYOR INCREASING OFF THE
WESTERN GULF WILL FUEL A NOCTURNAL MCS TYPE FEATURE SAT NIGHT INTO
SUNDAY MORNING ACRS MOST OF THE LOCAL FCST AREA. THIS WHILE THE
CONSISTENT ECMWF IS FURTHER SOUTH WITH LLVL BAROCLINIC RIBBON LAY
OUT AS WELL AS SOUTHWESTERN GRT LKS LLVL RIDGE AND NORTHEAST BOUNDARY
LAYER PUSH KEEPING THE DVN CWA MAINLY DRY EXCEPT FOR SOME
OVERRUNNING SHOWERS ACRS THE FAR SOUTH SAT NIGHT. THE CANADIAN MORE
SIMILAR TO THE GFS FOR SAT NIGHT AND ADVERTISES UP TO 1.5 INCHES OF
RAIN ACRS THE HEART OF THE CWA BY 12Z SUNDAY. WITH UNCERTAINTIES...
WILL HAVE TO KEEP CHC POPS FOR ALMOST EVERY PERIOD WHICH WILL BE AN
UNFORTUNATE THEME THAT WILL LOOK TO REOCCUR THROUGH THE REST OF THE
LONG RANGE. BOUNDARY PLACEMENT...PRECIP EPISODES AND OUTFLOW/CLOUD
DEBRIS TO PLAY HAVOC WITH TEMP FCST/S THROUGH THE HOLIDAY WEEKEND.
SUNDAY THROUGH NEXT TUESDAY...AS STATED ABOVE...LARGE DIFFERENCES IN
MID CONUS RIDGE PLACEMENT OF THE MAIN AXIS AND AMPLIFICATION...AS
WELL AS NORTH-SOUTH LAY OUT DIFFERENCES OF WEST-TO-EAST ORIENTED LLVL
BOUNDARY OR H85 FRONT BETWEEN THE MEDIUM RANGE MODELS WILL AVERAGE
OUT TO DAILY CHC POPS THOUGH MOST OF THIS PERIOD. THE NEW EURO
CONTINUES TO BE FURTHER SOUTH WITH THE QUASI-STATIONARY LLVL
THERMAL RIBBON THAT PRECIP WILL FOCUS ON AND OVER AND KEEP MOST OF
THE CWA DRY UNTIL TUE...JUST BATHED IN SEASONABLY COOL NORTHEAST
OR EASTERLY FLOW WITH JUST THE FAR SOUTHERN CWA GETTING CLIPPED BY
OVERRUNNING SHOWERS. THIS WHILE THE GFS AND GEM ARE FURTHER NORTH
WITH THE LLVL CONVERGENT AXIS AN BREAK OUT PERIODIC EPISODES OF
ELEVATED SHOWERS OR EVEN POSSIBLE MCS TYPE PRECIP COMPLEXES THROUGH
THE HOLIDAY WEEKEND OVER THE REGION. CLIMATOLOGY SUGGESTS A
COMPROMISE BETWEEN THE TWO CAMPS OF MODELS THAT THE SOUTHERN THIRD TO
HALF OF THE DVN CWA WILL BE UNDER THE GUN FOR A SOGGY HOLIDAY
WEEKEND. BELOW NORMAL TEMPS NORTH OF ANY BOUNDARY THAT SETS UP
ALONG OR JUST SOUTH OF THE CWA...POSSIBLY IN THE LOW 60S OR EVEN 50S
IF OVERRUNNING RAINS WIN OUT WHILE LAKE ENHANCED NORTHEAST SFC FLOW
SPILLS ACRS THE AREA ESPECIALLY ON SUNDAY. DIFFERENCES CONTINUE INTO
TUE AS THE GFS TRENDS DRIER SHIFTING THE MCS TRACK TO THE NORTH ACRS
MN AND WI FOR THE MID WEEK PERIOD...WHILE THE ECMWF ALSO TRENDS
NORTH BUT THAT TARGETS IA AND NORTHERN IL FOR A FAVORED MCS TRACK
FOR THE MID WEEK PERIOD. ..12..
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1208 PM CDT TUE MAY 21 2013
STALLED LOW PRESSURE OVER MN WILL WILL DROP SOUTHEAST THROUGH
EASTERN IA AND WEAKEN LATE TONIGHT AND WEDNESDAY MORNING.
WIDESPREAD CU BASED AROUND 35HND FEET THIS AFTERNOON WILL
DISSIPATE WITH LOSS OF HEATING BY EARLY THIS EVENING. AN AREA OF
SHOWERS WILL LIFT NORTHEAST BRUSHING LOCATIONS NEAR AND EAST OF
THE MISSISSIPPI RIVER LATE TONIGHT AND WEDNESDAY. AT THIS TIME IT
APPEARS FLIGHT CONDITIONS WILL REMAIN VFR IN THE SHOWERS EXCEPT AT
KDBQ WHERE CIGS COULD DROP BELOW 3KFT. FURTHER WEST...AN AREA OF
MVFR CLOUDS AND SCATTERED SHRA WILL ACCOMPANY THE WEAKENING LOW
PRESSURE AS IT MOVES THROUGH THE REGION. MVFR CIGS SHOULD REACH KCID
AFTER 12Z WEDNESDAY.
DLF
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...DLF
SHORT TERM...DLF
LONG TERM...12
AVIATION...DLF
000
FXUS63 KDMX 211816
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
116 PM CDT TUE MAY 21 2013
.UPDATE...
ISSUED AT 115 PM CDT TUE MAY 21 2013
LOWERED HIGH TEMPERATURES AND INCREASED CLOUD COVER FOR THIS
AFTERNOON...ESPECIALLY ACROSS THE NORTH...WITH UPPER LEVEL LOW
PARKED OVER SOUTHEAST SOUTH DAKOTA AND STRATOCU FILLING IN ACROSS
THE CWA. TEMPERATURES ACROSS THE FAR NORTH HAVE ONLY RISEN A FEW
DEGREES THUS FAR TODAY AND SHOULD ONLY GO UP SLIGHTLY MORE THIS
AFTERNOON. HIGH TEMP FORECAST LOOKS ON TRACK IN THE SOUTHEAST
WHERE CLOUDS HAVE NOT FILLED IN.
&&
.SHORT TERM.../TODAY /...
ISSUED AT 257 AM CDT TUE MAY 21 2013
UPPER LOW NEAR ABERDEEN SOUTH DAKOTA WILL DRIFT VERY GRADUALLY TO
THE SOUTHEAST TODAY. SUBSIDENCE IS EXPECTED TO BE IN PLACE ACROSS
SOUTHERN IOWA FOR MUCH OF THE DAY WITH SOME LIFT FARTHER NORTH NEAR
MINNESOTA. HOWEVER...MOISTURE IS MORE LIMITED THAN PREVIOUS DAYS AND
THE THREAT OF PRECIPITATION LOOKS RATHER MINIMAL THROUGH THE
DAYTIME. CLOUDS ASSOCIATED WITH COMMA HEAD OF SYSTEM WILL LIKELY
BE IN PLACE ACROSS MUCH OF THE NORTHWEST THIRD TO HALF OF THE
FORECAST AREA DURING THE DAY. IN ADDITION...COLD ADVECTION WILL
PERSIST THROUGH THE DAY AS 850MB DROP TO AROUND +5C BY 00Z THIS
EVENING AND ANTICIPATE TEMPERATURES TO BE QUITE COOL IN THE
NORTHWEST TODAY AND HAVE GENERALLY UNDERCUT GUIDANCE. DEEPER
SATURATION ASSOCIATED WITH THE DEFORMATION ZONE WILL ARRIVE IN THE
NORTHWEST TOWARD THE END OF THE PERIOD BUT NOT IN TIME FOR PCPN
THREAT UNTIL TONIGHT.
.LONG TERM.../TONIGHT THROUGH SUNDAY/...
ISSUED AT 257 AM CDT TUE MAY 21 2013
THE LARGE UPPER LOW PRESSURE SYSTEM THAT HAS PLAGUED THE CENTRAL
U.S. FOR THE PAST DAY OR TWO WILL FINALLY BEGIN TO MOVE EASTWARD
TONIGHT...MOVING OVER IOWA ON WEDNESDAY AND THEN OFF TO THE EAST
THEREAFTER. AS A RESULT A LARGE AREA OF CLOUDS AND LIGHT RAIN
SHOWERS WILL MOVE INTO OUR CWA LATE TONIGHT AND PERSIST FOR MOST
OF WEDNESDAY BEFORE TAPERING OFF WEDNESDAY NIGHT. WHILE QPF IS
QUITE LIGHT...RAINFALL APPEARS FAIRLY PROBABLE AND HAVE INCREASED
POPS A BIT ON WEDNESDAY...BUT HELD OFF ON LIKELIES FOR NOW DUE TO
THE EXPECTED PATCHY NATURE OF THE PRECIPITATION. A LITTLE ELEVATED
INSTABILITY WILL SUPPORT THE POSSIBILITY OF A FEW THUNDERSTORMS
MAINLY ON WEDNESDAY AFTERNOON...BUT THE OVERALL SCENARIO IS NOT
CONDUCIVE FOR ANY SEVERE WEATHER THREAT.
AS THE SYSTEM AND LIGHT RAIN DEPART TO THE EAST ON WEDNESDAY
NIGHT/THURSDAY MORNING A LARGE HIGH PRESSURE RIDGE WILL BUILD DOWN
INTO THE REGION BRINGING COOL AND DRY WEATHER FOR THE REMAINDER OF
THE WORK WEEK. BY FRIDAY NIGHT THE AXIS OF A WEAK 500 MB RIDGE
WILL MOVE OVERHEAD...AND AFTER THIS THE FORECAST BECOMES MORE
UNCERTAIN. BEHIND THIS RIDGE AXIS LURK SEVERAL WEAK MID-LEVEL
IMPULSES THAT WILL PROVIDE THE IMPETUS FOR SHOWER/THUNDERSTORM
DEVELOPMENT AT TIMES THIS WEEKEND AND INTO EARLY NEXT
WEEK...CONCURRENT WITH A RETURN OF ROUGHLY SOUTHERLY LOW-LEVEL
FLOW AS THE AFOREMENTIONED SURFACE HIGH MOVES AWAY. THIS WILL
SUPPORT INTERMITTENT RAINFALL CHANCES ACROSS THE AREA...HOWEVER
THE TIMING AND LOCATION OF THESE CHANCES IS VERY UNCERTAIN DUE TO
THE WEAK NATURE OF THE FORCING SYSTEMS. IN ADDITION...IT APPEARS
LIKELY THAT A SURFACE LOW PRESSURE AREA WILL DEVELOP IN THE LEE OF
THE ROCKIES AND EXTEND A WARM FRONT EASTWARD ACROSS THE
REGION...PROVIDING AN ENHANCED AND FAVORED LOCATION FOR SHOWERS
AND STORMS DURING THE ENSUING PERIOD. THE GFS AND GEM BOTH DEVELOP
THIS FEATURE ACROSS IOWA BUT THE ECMWF IS CONSISTENTLY FORCING IT
FURTHER SOUTH ACROSS MISSOURI...WHICH WOULD RESULT IN A LARGELY
DRY FORECAST FOR CENTRAL IOWA. GIVEN THESE COMPETING FACTORS HAVE
STUCK WITH SEVERAL PERIODS OF CHANCE POPS IN THE EXTENDED...BUT
THIS WILL NEED TO BE REFINED AS THE SCENARIO COMES INTO BETTER
FOCUS OVER THE NEXT COUPLE OF DAYS.
&&
.AVIATION...21/18Z
ISSUED AT 1243 PM CDT TUE MAY 21 2013
WIDESPREAD STRATOCUMULUS WILL CONTINUE TO CIRCULATE AROUND A SLOW
MOVING UPPER LOW OVER MINNESOTA THROUGH WEDNESDAY. THERE HAS BEEN
A DIURNAL INCREASE IN CIG HEIGHT TO VFR LEVELS THROUGH THIS
MORNING...AND VFR CIGS AROUND 3500 TO 5000 FT WILL CONTINUE
THROUGH EARLY EVENING...WHEN DIURNALLY THEY WILL DROP BACK TO MVFR
LEVELS. IN ADDITION...COLDER AIR ARRIVING ALOFT WILL HELP DROP
CIGS TO THE 1000 TO 1800 FT LEVELS. VISIBILITIES SHOULD REMAIN
GOOD...THROUGH A FEW SHOWERS MAY IMPACT LOCATIONS NORTH OF
INTERSTATE 80 DURING THE DAY WEDNESDAY. WINDS WILL BE MAINLY WEST
TO SOUTHWEST TODAY AT 12 TO 20 KTS...AND NORTHWEST OVERNIGHT AND
WEDNESDAY...AROUND 10 KTS.
ERVIN
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...SKOW
SHORT TERM...COGIL
LONG TERM...LEE
AVIATION...ERVIN/DVN
000
FXUS63 KDMX 211747
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1247 PM CDT TUE MAY 21 2013
.SHORT TERM.../TODAY /...
ISSUED AT 257 AM CDT TUE MAY 21 2013
UPPER LOW NEAR ABERDEEN SOUTH DAKOTA WILL DRIFT VERY GRADUALLY TO
THE SOUTHEAST TODAY. SUBSIDENCE IS EXPECTED TO BE IN PLACE ACROSS
SOUTHERN IOWA FOR MUCH OF THE DAY WITH SOME LIFT FARTHER NORTH NEAR
MINNESOTA. HOWEVER...MOISTURE IS MORE LIMITED THAN PREVIOUS DAYS AND
THE THREAT OF PRECIPITATION LOOKS RATHER MINIMAL THROUGH THE
DAYTIME. CLOUDS ASSOCIATED WITH COMMA HEAD OF SYSTEM WILL LIKELY
BE IN PLACE ACROSS MUCH OF THE NORTHWEST THIRD TO HALF OF THE
FORECAST AREA DURING THE DAY. IN ADDITION...COLD ADVECTION WILL
PERSIST THROUGH THE DAY AS 850MB DROP TO AROUND +5C BY 00Z THIS
EVENING AND ANTICIPATE TEMPERATURES TO BE QUITE COOL IN THE
NORTHWEST TODAY AND HAVE GENERALLY UNDERCUT GUIDANCE. DEEPER
SATURATION ASSOCIATED WITH THE DEFORMATION ZONE WILL ARRIVE IN THE
NORTHWEST TOWARD THE END OF THE PERIOD BUT NOT IN TIME FOR PCPN
THREAT UNTIL TONIGHT.
.LONG TERM.../TONIGHT THROUGH SUNDAY/...
ISSUED AT 257 AM CDT TUE MAY 21 2013
THE LARGE UPPER LOW PRESSURE SYSTEM THAT HAS PLAGUED THE CENTRAL
U.S. FOR THE PAST DAY OR TWO WILL FINALLY BEGIN TO MOVE EASTWARD
TONIGHT...MOVING OVER IOWA ON WEDNESDAY AND THEN OFF TO THE EAST
THEREAFTER. AS A RESULT A LARGE AREA OF CLOUDS AND LIGHT RAIN
SHOWERS WILL MOVE INTO OUR CWA LATE TONIGHT AND PERSIST FOR MOST
OF WEDNESDAY BEFORE TAPERING OFF WEDNESDAY NIGHT. WHILE QPF IS
QUITE LIGHT...RAINFALL APPEARS FAIRLY PROBABLE AND HAVE INCREASED
POPS A BIT ON WEDNESDAY...BUT HELD OFF ON LIKELIES FOR NOW DUE TO
THE EXPECTED PATCHY NATURE OF THE PRECIPITATION. A LITTLE ELEVATED
INSTABILITY WILL SUPPORT THE POSSIBILITY OF A FEW THUNDERSTORMS
MAINLY ON WEDNESDAY AFTERNOON...BUT THE OVERALL SCENARIO IS NOT
CONDUCIVE FOR ANY SEVERE WEATHER THREAT.
AS THE SYSTEM AND LIGHT RAIN DEPART TO THE EAST ON WEDNESDAY
NIGHT/THURSDAY MORNING A LARGE HIGH PRESSURE RIDGE WILL BUILD DOWN
INTO THE REGION BRINGING COOL AND DRY WEATHER FOR THE REMAINDER OF
THE WORK WEEK. BY FRIDAY NIGHT THE AXIS OF A WEAK 500 MB RIDGE
WILL MOVE OVERHEAD...AND AFTER THIS THE FORECAST BECOMES MORE
UNCERTAIN. BEHIND THIS RIDGE AXIS LURK SEVERAL WEAK MID-LEVEL
IMPULSES THAT WILL PROVIDE THE IMPETUS FOR SHOWER/THUNDERSTORM
DEVELOPMENT AT TIMES THIS WEEKEND AND INTO EARLY NEXT
WEEK...CONCURRENT WITH A RETURN OF ROUGHLY SOUTHERLY LOW-LEVEL
FLOW AS THE AFOREMENTIONED SURFACE HIGH MOVES AWAY. THIS WILL
SUPPORT INTERMITTENT RAINFALL CHANCES ACROSS THE AREA...HOWEVER
THE TIMING AND LOCATION OF THESE CHANCES IS VERY UNCERTAIN DUE TO
THE WEAK NATURE OF THE FORCING SYSTEMS. IN ADDITION...IT APPEARS
LIKELY THAT A SURFACE LOW PRESSURE AREA WILL DEVELOP IN THE LEE OF
THE ROCKIES AND EXTEND A WARM FRONT EASTWARD ACROSS THE
REGION...PROVIDING AN ENHANCED AND FAVORED LOCATION FOR SHOWERS
AND STORMS DURING THE ENSUING PERIOD. THE GFS AND GEM BOTH DEVELOP
THIS FEATURE ACROSS IOWA BUT THE ECMWF IS CONSISTENTLY FORCING IT
FURTHER SOUTH ACROSS MISSOURI...WHICH WOULD RESULT IN A LARGELY
DRY FORECAST FOR CENTRAL IOWA. GIVEN THESE COMPETING FACTORS HAVE
STUCK WITH SEVERAL PERIODS OF CHANCE POPS IN THE EXTENDED...BUT
THIS WILL NEED TO BE REFINED AS THE SCENARIO COMES INTO BETTER
FOCUS OVER THE NEXT COUPLE OF DAYS.
&&
.AVIATION...21/18Z
ISSUED AT 1243 PM CDT TUE MAY 21 2013
WIDESPREAD STRATOCUMULUS WILL CONTINUE TO CIRCULATE AROUND A SLOW
MOVING UPPER LOW OVER MINNESOTA THROUGH WEDNESDAY. THERE HAS BEEN
A DIURNAL INCREASE IN CIG HEIGHT TO VFR LEVELS THROUGH THIS
MORNING...AND VFR CIGS AROUND 3500 TO 5000 FT WILL CONTINUE
THROUGH EARLY EVENING...WHEN DIURNALLY THEY WILL DROP BACK TO MVFR
LEVELS. IN ADDITION...COLDER AIR ARRIVING ALOFT WILL HELP DROP
CIGS TO THE 1000 TO 1800 FT LEVELS. VISIBILITIES SHOULD REMAIN
GOOD...THROUGH A FEW SHOWERS MAY IMPACT LOCATIONS NORTH OF
INTERSTATE 80 DURING THE DAY WEDNESDAY. WINDS WILL BE MAINLY WEST
TO SOUTHWEST TODAY AT 12 TO 20 KTS...AND NORTHWEST OVERNIGHT AND
WEDNESDAY...AROUND 10 KTS.
ERVIN
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...COGIL
LONG TERM...LEE
AVIATION...ERVIN/DVN
000
FXUS63 KDVN 211717
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1217 PM CDT TUE MAY 21 2013
.SYNOPSIS...
ISSUED AT 255 AM CDT TUE MAY 21 2013
ANALYSIS SHOWS LARGE SURFACE AND UPPER LOW SYSTEM PIN WHEELING ACROSS
THE EASTERN DAKOTAS MOVING SLOWLY SOUTHEAST. THIS PUTS FORECAST AREA
IN DRY SLOT WHICH WILL CONTINUE FOR ROUGHLY THE NEXT 12-15 HOURS.
DIFFUSE COOL FRONT WILL MOVE ACROSS THE AREA THIS EVENING BRINGING
CLOUDS AND COOLER TEMPERATURES. VERIFICATION AT 2 AM SHOWS COOL
AIR ON BACK SIDE OF SYSTEM ON THE STRONGER SIDE OF ALL SOLUTIONS.
UPSTREAM ENERGY SUPPORTS BELOW NORMAL TEMPERATURES AND ACTIVE
WESTERLY FLOW THE NEXT 5 PLUS DAYS AND POSSIBLY LONGER.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 255 AM CDT TUE MAY 21 2013
TODAY...SOUTHWEST WINDS WILL INCREASE TO 15 TO 25 MPH BY MID DAY
WITH PARTLY TO MOSTLY SUNNY SKIES. THIS WILL RESULT IN A DAY SIMILAR
TO YESTERDAY WITH LOWERING DEWPOINTS AND HIGHS A DEGREE OR TWO
LOWER TODAY FOR A NICE AND COMFORTABLE LATE SPRING DAY. HAVE KEPT
ISOLATED SHOWER OR THUNDERSTORM LOCATIONS MAINLY EAST OF THE
MISSISSIPPI RIVER MID TO LATE PM BUT LATER SHIFTS MAY BE ABLE TO
REMOVE DUE TO MIXING OF LOWER DEWPOINTS AND LACK OF A FORCING
FOCUS. HIGHS SHOULD RANGE FROM AROUND 73-74 FAR NW TO 80-82 SE
SECTIONS.
TONIGHT...CLOUDS TO INCREASE WITH WAVE FROM SOUTHERN PLAINS TO IMPACT
LOCATIONS ALONG AND EAST OF THE MISSISSIPPI TOWARD DAYBREAK. UPPED
POPS TO LIKELY FAR EAST WITH SHOWERS AND MORE PROBABLY JUST LIGHT RAIN.
THE MOSTLY SLIGHT CHANCE EVENING POPS OF THUNDER MAY BE ABLE TO CHANGED
TO JUST SHOWERS WITH LACK OF FOCUS AND INSTABILITY BY LATER SHIFTS.
NICHOLS
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 255 AM CDT TUE MAY 21 2013
THE MODELS SHOW A RESPECTABLE SURFACE WAVE MOVING THROUGH THE AREA
ON WEDNESDAY BRINGING A THREAT OF RAIN TO THE AREA. THE POSSIBILITY
OF THUNDERSTORMS IS QUESTIONABLE GIVEN HOW COOL THE AIRMASS IS AND
WHAT IS SUGGESTED IN THE FCST SOUNDINGS. HOWEVER...HAVE ELECTED TO
KEEP A MENTION OF ISOLATED THUNDERSTORMS OVER ROUGHLY THE EASTERN
HALF OF THE CWFA WED AFTERNOON WHERE SLIGHTLY STRONGER LIFT IS
INDICATED BY THE MODELS.
WED NIGHT/THURSDAY MORNING SHOWERS WILL PERSIST ACROSS THE AREA AS
THE SFC LOW SLOWLY MOVES EAST INTO INDIANA. BY THURSDAY AFTERNOON
MOST OF THE AREA SHOULD BE DRY AS THE BETTER MOISTURE AND FORCING
MOVES EAST OF THE AREA. TEMPERATURES ON THURSDAY WILL BE BELOW
NORMAL.
THURSDAY NIGHT WILL BE CHILLY AND DRY AS A VERY COOL CANADIAN
AIRMASS BUILDS INTO THE AREA.
FRIDAY ON...
THE MODEL CONSENSUS HAS COOL AND DRY CONDITIONS ACROSS THE AREA ON
FRIDAY WITH CANADIAN HIGH PRESSURE OVER THE GREAT LAKES.
THE MODEL CONSENSUS HAS SCHC/CHC POPS FRIDAY NIGHT AND THEN CHC POPS
FROM SATURDAY THROUGH MONDAY. THE MODELS GENERALLY AGREE ON
DEVELOPING RETURN FLOW FRIDAY NIGHT BUT THE STRENGTH OF THE CANADIAN
HIGH COMBINED WITH FLOW OFF LAKE MICHIGAN WILL HELP KEEP AN
EFFECTIVE BOUNDARY ACROSS THE AREA. DISTURBANCES ARRIVING FROM THE
PLAINS WILL INTERACT WITH THIS BOUNDARY AND BRING A NEAR DAILY
THREAT OF RAIN TO THE AREA FROM SATURDAY THROUGH MONDAY.
THE FLOW OFF LAKE MICHIGAN WILL ALSO RESULT IN TEMPERATURES WELL
BELOW NORMAL FROM FRIDAY THROUGH SUNDAY.
08
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)
ISSUED AT 1208 PM CDT TUE MAY 21 2013
STALLED LOW PRESSURE OVER MN WILL WILL DROP SOUTHEAST THROUGH
EASTERN IA AND WEAKEN LATE TONIGHT AND WEDNESDAY MORNING.
WIDESPREAD CU BASED AROUND 35HND FEET THIS AFTERNOON WILL
DISSIPATE WITH LOSS OF HEATING BY EARLY THIS EVENING. AN AREA OF
SHOWERS WILL LIFT NORTHEAST BRUSHING LOCATIONS NEAR AND EAST OF
THE MISSISSIPPI RIVER LATE TONIGHT AND WEDNESDAY. AT THIS TIME IT
APPEARS FLIGHT CONDITIONS WILL REMAIN VFR IN THE SHOWERS EXCEPT AT
KDBQ WHERE CIGS COULD DROP BELOW 3KFT. FURTHER WEST...AN AREA OF
MVFR CLOUDS AND SCATTERED SHRA WILL ACCOMPANY THE WEAKENING LOW
PRESSURE AS IT MOVES THROUGH THE REGION. MVFR CIGS SHOULD REACH KCID
AFTER 12Z WEDNESDAY.
DLF
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...NICHOLS
SHORT TERM...NICHOLS
LONG TERM...08
AVIATION...DLF
000
FXUS63 KDVN 211142
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
642 AM CDT TUE MAY 21 2013
.SYNOPSIS...
ISSUED AT 255 AM CDT TUE MAY 21 2013
ANALYSIS SHOWS LARGE SURFACE AND UPPER LOW SYSTEM PIN WHEELING ACROSS
THE EASTERN DAKOTAS MOVING SLOWLY SOUTHEAST. THIS PUTS FORECAST AREA
IN DRY SLOT WHICH WILL CONTINUE FOR ROUGHLY THE NEXT 12-15 HOURS.
DIFFUSE COOL FRONT WILL MOVE ACROSS THE AREA THIS EVENING BRINGING
CLOUDS AND COOLER TEMPERATURES. VERIFICATION AT 2 AM SHOWS COOL
AIR ON BACK SIDE OF SYSTEM ON THE STRONGER SIDE OF ALL SOLUTIONS.
UPSTREAM ENERGY SUPPORTS BELOW NORMAL TEMPERATURES AND ACTIVE
WESTERLY FLOW THE NEXT 5 PLUS DAYS AND POSSIBLY LONGER.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 255 AM CDT TUE MAY 21 2013
TODAY...SOUTHWEST WINDS WILL INCREASE TO 15 TO 25 MPH BY MID DAY
WITH PARTLY TO MOSTLY SUNNY SKIES. THIS WILL RESULT IN A DAY SIMILAR
TO YESTERDAY WITH LOWERING DEWPOINTS AND HIGHS A DEGREE OR TWO
LOWER TODAY FOR A NICE AND COMFORTABLE LATE SPRING DAY. HAVE KEPT
ISOLATED SHOWER OR THUNDERSTORM LOCATIONS MAINLY EAST OF THE
MISSISSIPPI RIVER MID TO LATE PM BUT LATER SHIFTS MAY BE ABLE TO
REMOVE DUE TO MIXING OF LOWER DEWPOINTS AND LACK OF A FORCING
FOCUS. HIGHS SHOULD RANGE FROM AROUND 73-74 FAR NW TO 80-82 SE
SECTIONS.
TONIGHT...CLOUDS TO INCREASE WITH WAVE FROM SOUTHERN PLAINS TO IMPACT
LOCATIONS ALONG AND EAST OF THE MISSISSIPPI TOWARD DAYBREAK. UPPED
POPS TO LIKELY FAR EAST WITH SHOWERS AND MORE PROBABLY JUST LIGHT RAIN.
THE MOSTLY SLIGHT CHANCE EVENING POPS OF THUNDER MAY BE ABLE TO CHANGED
TO JUST SHOWERS WITH LACK OF FOCUS AND INSTABILITY BY LATER SHIFTS.
NICHOLS
.LONG TERM...(WEDNESDAY THROUGH MONDAY)
ISSUED AT 255 AM CDT TUE MAY 21 2013
THE MODELS SHOW A RESPECTABLE SURFACE WAVE MOVING THROUGH THE AREA
ON WEDNESDAY BRINGING A THREAT OF RAIN TO THE AREA. THE POSSIBILITY
OF THUNDERSTORMS IS QUESTIONABLE GIVEN HOW COOL THE AIRMASS IS AND
WHAT IS SUGGESTED IN THE FCST SOUNDINGS. HOWEVER...HAVE ELECTED TO
KEEP A MENTION OF ISOLATED THUNDERSTORMS OVER ROUGHLY THE EASTERN
HALF OF THE CWFA WED AFTERNOON WHERE SLIGHTLY STRONGER LIFT IS
INDICATED BY THE MODELS.
WED NIGHT/THURSDAY MORNING SHOWERS WILL PERSIST ACROSS THE AREA AS
THE SFC LOW SLOWLY MOVES EAST INTO INDIANA. BY THURSDAY AFTERNOON
MOST OF THE AREA SHOULD BE DRY AS THE BETTER MOISTURE AND FORCING
MOVES EAST OF THE AREA. TEMPERATURES ON THURSDAY WILL BE BELOW
NORMAL.
THURSDAY NIGHT WILL BE CHILLY AND DRY AS A VERY COOL CANADIAN
AIRMASS BUILDS INTO THE AREA.
FRIDAY ON...
THE MODEL CONSENSUS HAS COOL AND DRY CONDITIONS ACROSS THE AREA ON
FRIDAY WITH CANADIAN HIGH PRESSURE OVER THE GREAT LAKES.
THE MODEL CONSENSUS HAS SCHC/CHC POPS FRIDAY NIGHT AND THEN CHC POPS
FROM SATURDAY THROUGH MONDAY. THE MODELS GENERALLY AGREE ON
DEVELOPING RETURN FLOW FRIDAY NIGHT BUT THE STRENGTH OF THE CANADIAN
HIGH COMBINED WITH FLOW OFF LAKE MICHIGAN WILL HELP KEEP AN
EFFECTIVE BOUNDARY ACROSS THE AREA. DISTURBANCES ARRIVING FROM THE
PLAINS WILL INTERACT WITH THIS BOUNDARY AND BRING A NEAR DAILY
THREAT OF RAIN TO THE AREA FROM SATURDAY THROUGH MONDAY.
THE FLOW OFF LAKE MICHIGAN WILL ALSO RESULT IN TEMPERATURES WELL
BELOW NORMAL FROM FRIDAY THROUGH SUNDAY.
08
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING)
ISSUED AT 635 AM CDT TUE MAY 21 2013
SCT/BKN IFR CLOUD DECK TO DISSIPATE BY 15Z. THEN...VFR CONDITIONS
TO PREVAIL INTO WEDNESDAY MORNING. AREA TO EXPERIENCE SW WINDS OF
15 TO 25 MPH AND PARTLY SUNNY SKIES ALL TERMINALS WITH A DRY SLOT
AHEAD OF UPPER NORTHERN PLAINS LOW PRESSURE SYSTEM. DIFFUSE FRONT
TO PASS TONIGHT WITH A WAVE THAT MAY BRING A CHANCE OF LIGHT RAIN
AND CIGS TO BRL-MLI TERMINALS OF 3-5K AGL BY 22/12Z.
NICHOLS
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...NICHOLS
SHORT TERM...NICHOLS
LONG TERM...08
AVIATION...NICHOLS
000
FXUS63 KDMX 211138
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
638 AM CDT TUE MAY 21 2013
.SHORT TERM.../TODAY /...
ISSUED AT 257 AM CDT TUE MAY 21 2013
UPPER LOW NEAR ABERDEEN SOUTH DAKOTA WILL DRIFT VERY GRADUALLY TO
THE SOUTHEAST TODAY. SUBSIDENCE IS EXPECTED TO BE IN PLACE ACROSS
SOUTHERN IOWA FOR MUCH OF THE DAY WITH SOME LIFT FARTHER NORTH NEAR
MINNESOTA. HOWEVER...MOISTURE IS MORE LIMITED THAN PREVIOUS DAYS AND
THE THREAT OF PRECIPITATION LOOKS RATHER MINIMAL THROUGH THE
DAYTIME. CLOUDS ASSOCIATED WITH COMMA HEAD OF SYSTEM WILL LIKELY
BE IN PLACE ACROSS MUCH OF THE NORTHWEST THIRD TO HALF OF THE
FORECAST AREA DURING THE DAY. IN ADDITION...COLD ADVECTION WILL
PERSIST THROUGH THE DAY AS 850MB DROP TO AROUND +5C BY 00Z THIS
EVENING AND ANTICIPATE TEMPERATURES TO BE QUITE COOL IN THE
NORTHWEST TODAY AND HAVE GENERALLY UNDERCUT GUIDANCE. DEEPER
SATURATION ASSOCIATED WITH THE DEFORMATION ZONE WILL ARRIVE IN THE
NORTHWEST TOWARD THE END OF THE PERIOD BUT NOT IN TIME FOR PCPN
THREAT UNTIL TONIGHT.
.LONG TERM.../TONIGHT THROUGH SUNDAY/...
ISSUED AT 257 AM CDT TUE MAY 21 2013
THE LARGE UPPER LOW PRESSURE SYSTEM THAT HAS PLAGUED THE CENTRAL
U.S. FOR THE PAST DAY OR TWO WILL FINALLY BEGIN TO MOVE EASTWARD
TONIGHT...MOVING OVER IOWA ON WEDNESDAY AND THEN OFF TO THE EAST
THEREAFTER. AS A RESULT A LARGE AREA OF CLOUDS AND LIGHT RAIN
SHOWERS WILL MOVE INTO OUR CWA LATE TONIGHT AND PERSIST FOR MOST
OF WEDNESDAY BEFORE TAPERING OFF WEDNESDAY NIGHT. WHILE QPF IS
QUITE LIGHT...RAINFALL APPEARS FAIRLY PROBABLE AND HAVE INCREASED
POPS A BIT ON WEDNESDAY...BUT HELD OFF ON LIKELIES FOR NOW DUE TO
THE EXPECTED PATCHY NATURE OF THE PRECIPITATION. A LITTLE ELEVATED
INSTABILITY WILL SUPPORT THE POSSIBILITY OF A FEW THUNDERSTORMS
MAINLY ON WEDNESDAY AFTERNOON...BUT THE OVERALL SCENARIO IS NOT
CONDUCIVE FOR ANY SEVERE WEATHER THREAT.
AS THE SYSTEM AND LIGHT RAIN DEPART TO THE EAST ON WEDNESDAY
NIGHT/THURSDAY MORNING A LARGE HIGH PRESSURE RIDGE WILL BUILD DOWN
INTO THE REGION BRINGING COOL AND DRY WEATHER FOR THE REMAINDER OF
THE WORK WEEK. BY FRIDAY NIGHT THE AXIS OF A WEAK 500 MB RIDGE
WILL MOVE OVERHEAD...AND AFTER THIS THE FORECAST BECOMES MORE
UNCERTAIN. BEHIND THIS RIDGE AXIS LURK SEVERAL WEAK MID-LEVEL
IMPULSES THAT WILL PROVIDE THE IMPETUS FOR SHOWER/THUNDERSTORM
DEVELOPMENT AT TIMES THIS WEEKEND AND INTO EARLY NEXT
WEEK...CONCURRENT WITH A RETURN OF ROUGHLY SOUTHERLY LOW-LEVEL
FLOW AS THE AFOREMENTIONED SURFACE HIGH MOVES AWAY. THIS WILL
SUPPORT INTERMITTENT RAINFALL CHANCES ACROSS THE AREA...HOWEVER
THE TIMING AND LOCATION OF THESE CHANCES IS VERY UNCERTAIN DUE TO
THE WEAK NATURE OF THE FORCING SYSTEMS. IN ADDITION...IT APPEARS
LIKELY THAT A SURFACE LOW PRESSURE AREA WILL DEVELOP IN THE LEE OF
THE ROCKIES AND EXTEND A WARM FRONT EASTWARD ACROSS THE
REGION...PROVIDING AN ENHANCED AND FAVORED LOCATION FOR SHOWERS
AND STORMS DURING THE ENSUING PERIOD. THE GFS AND GEM BOTH DEVELOP
THIS FEATURE ACROSS IOWA BUT THE ECMWF IS CONSISTENTLY FORCING IT
FURTHER SOUTH ACROSS MISSOURI...WHICH WOULD RESULT IN A LARGELY
DRY FORECAST FOR CENTRAL IOWA. GIVEN THESE COMPETING FACTORS HAVE
STUCK WITH SEVERAL PERIODS OF CHANCE POPS IN THE EXTENDED...BUT
THIS WILL NEED TO BE REFINED AS THE SCENARIO COMES INTO BETTER
FOCUS OVER THE NEXT COUPLE OF DAYS.
&&
.AVIATION...21/12Z
ISSUED AT 635 AM CDT TUE MAY 21 2013
UPPER LOW OVER SOUTH DAKOTA WILL DRIFT SLOWLY SOUTHEAST DURING THE
FORECAST PERIOD WITH EXTENSIVE CLOUDINESS ACROSS IOWA. WILL SEE
MVFR CEILINGS ACROSS THE NORTH AND WEST THIS MORNING BUT THESE
SHOULD IMPROVE TO VFR WITH DAYTIME HEATING. SURFACE WINDS WILL BE
FROM THE WSW DURING THE DAY BEHIND A COLD FRONT CURRENTLY PASSING
THROUGH THE STATE. CEILINGS WILL FALL OVERNIGHT AS UPPER LOW
ENTERS THE STATE AND DEEPER SATURATION OCCURS AS DEFORMATION ZONE
SWEEPS INTO IOWA. WILL SEE MVFR CEILINGS BECOME WIDESPREAD ACROSS
THE NORTHWEST AFFECTING KFOD AND KMCW WITH THE THREAT OF SOME
SCATTERED SHOWERS TOWARD WEDNESDAY MORNING. VFR CONDITIONS WILL
LINGER ACROSS THE SOUTH AND EAST OVERNIGHT.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...COGIL
LONG TERM...LEE
AVIATION...COGIL
000
FXUS63 KDMX 210818
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
318 AM CDT TUE MAY 21 2013
.SHORT TERM.../TODAY /...
ISSUED AT 257 AM CDT TUE MAY 21 2013
UPPER LOW NEAR ABERDEEN SOUTH DAKOTA WILL DRIFT VERY GRADUALLY TO
THE SOUTHEAST TODAY. SUBSIDENCE IS EXPECTED TO BE IN PLACE ACROSS
SOUTHERN IOWA FOR MUCH OF THE DAY WITH SOME LIFT FARTHER NORTH NEAR
MINNESOTA. HOWEVER...MOISTURE IS MORE LIMITED THAN PREVIOUS DAYS AND
THE THREAT OF PRECIPITATION LOOKS RATHER MINIMAL THROUGH THE
DAYTIME. CLOUDS ASSOCIATED WITH COMMA HEAD OF SYSTEM WILL LIKELY
BE IN PLACE ACROSS MUCH OF THE NORTHWEST THIRD TO HALF OF THE
FORECAST AREA DURING THE DAY. IN ADDITION...COLD ADVECTION WILL
PERSIST THROUGH THE DAY AS 850MB DROP TO AROUND +5C BY 00Z THIS
EVENING AND ANTICIPATE TEMPERATURES TO BE QUITE COOL IN THE
NORTHWEST TODAY AND HAVE GENERALLY UNDERCUT GUIDANCE. DEEPER
SATURATION ASSOCIATED WITH THE DEFORMATION ZONE WILL ARRIVE IN THE
NORTHWEST TOWARD THE END OF THE PERIOD BUT NOT IN TIME FOR PCPN
THREAT UNTIL TONIGHT.
.LONG TERM.../TONIGHT THROUGH SUNDAY/...
ISSUED AT 257 AM CDT TUE MAY 21 2013
THE LARGE UPPER LOW PRESSURE SYSTEM THAT HAS PLAGUED THE CENTRAL
U.S. FOR THE PAST DAY OR TWO WILL FINALLY BEGIN TO MOVE EASTWARD
TONIGHT...MOVING OVER IOWA ON WEDNESDAY AND THEN OFF TO THE EAST
THEREAFTER. AS A RESULT A LARGE AREA OF CLOUDS AND LIGHT RAIN
SHOWERS WILL MOVE INTO OUR CWA LATE TONIGHT AND PERSIST FOR MOST
OF WEDNESDAY BEFORE TAPERING OFF WEDNESDAY NIGHT. WHILE QPF IS
QUITE LIGHT...RAINFALL APPEARS FAIRLY PROBABLE AND HAVE INCREASED
POPS A BIT ON WEDNESDAY...BUT HELD OFF ON LIKELIES FOR NOW DUE TO
THE EXPECTED PATCHY NATURE OF THE PRECIPITATION. A LITTLE ELEVATED
INSTABILITY WILL SUPPORT THE POSSIBILITY OF A FEW THUNDERSTORMS
MAINLY ON WEDNESDAY AFTERNOON...BUT THE OVERALL SCENARIO IS NOT
CONDUCIVE FOR ANY SEVERE WEATHER THREAT.
AS THE SYSTEM AND LIGHT RAIN DEPART TO THE EAST ON WEDNESDAY
NIGHT/THURSDAY MORNING A LARGE HIGH PRESSURE RIDGE WILL BUILD DOWN
INTO THE REGION BRINGING COOL AND DRY WEATHER FOR THE REMAINDER OF
THE WORK WEEK. BY FRIDAY NIGHT THE AXIS OF A WEAK 500 MB RIDGE
WILL MOVE OVERHEAD...AND AFTER THIS THE FORECAST BECOMES MORE
UNCERTAIN. BEHIND THIS RIDGE AXIS LURK SEVERAL WEAK MID-LEVEL
IMPULSES THAT WILL PROVIDE THE IMPETUS FOR SHOWER/THUNDERSTORM
DEVELOPMENT AT TIMES THIS WEEKEND AND INTO EARLY NEXT
WEEK...CONCURRENT WITH A RETURN OF ROUGHLY SOUTHERLY LOW-LEVEL
FLOW AS THE AFOREMENTIONED SURFACE HIGH MOVES AWAY. THIS WILL
SUPPORT INTERMITTENT RAINFALL CHANCES ACROSS THE AREA...HOWEVER
THE TIMING AND LOCATION OF THESE CHANCES IS VERY UNCERTAIN DUE TO
THE WEAK NATURE OF THE FORCING SYSTEMS. IN ADDITION...IT APPEARS
LIKELY THAT A SURFACE LOW PRESSURE AREA WILL DEVELOP IN THE LEE OF
THE ROCKIES AND EXTEND A WARM FRONT EASTWARD ACROSS THE
REGION...PROVIDING AN ENHANCED AND FAVORED LOCATION FOR SHOWERS
AND STORMS DURING THE ENSUING PERIOD. THE GFS AND GEM BOTH DEVELOP
THIS FEATURE ACROSS IOWA BUT THE ECMWF IS CONSISTENTLY FORCING IT
FURTHER SOUTH ACROSS MISSOURI...WHICH WOULD RESULT IN A LARGELY
DRY FORECAST FOR CENTRAL IOWA. GIVEN THESE COMPETING FACTORS HAVE
STUCK WITH SEVERAL PERIODS OF CHANCE POPS IN THE EXTENDED...BUT
THIS WILL NEED TO BE REFINED AS THE SCENARIO COMES INTO BETTER
FOCUS OVER THE NEXT COUPLE OF DAYS.
&&
.AVIATION...21/00Z
ISSUED AT 730 PM CDT MON MAY 20 2013
CYCLONIC CIRCULATION OVER THE STATE HAS HELPED SET OFF
THUNDERSTORMS THIS EVENING. TWO MAIN LINES OVER NORTHWEST
IOWA...AND ALSO FROM SOUTHWEST INTO CENTRAL IOWA. TSRA WILL
DISSIPATE BY AROUND 06Z WITH SCT-BKN MVFR CIGS AROUND THE STATE
LATE TONIGHT INTO TUE MORNING. VFR CONDITIONS EXPECTED TUE WITH
RE-DEVELOPMENT OF TSRA OVR THE ERN TAF SITES POSSIBLE.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...COGIL
LONG TERM...LEE
AVIATION...MS MAY 13
000
FXUS63 KDVN 210543
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1243 AM CDT TUE MAY 21 2013
.SYNOPSIS...
ISSUED AT 248 PM CDT MON MAY 20 2013
LATEST SFC ANALYSIS WAS INDICATING OCCLUDING CYCLONE COMPLEX ACRS
THE EASTERN SD/ND REGION...WITH LEAD FRONT PUSHING ACRS WESTERN IA
BUT BETTER COLD WRAP AROUND NOTED ACRS SD INTO CENTRAL NEB. THE
REGION HAS BEEN PRETTY MUCH BATHED IN PRESSURE RISES TODAY...BUT
FALLS INCREASING ACRS WESTERN AND NORTHWESTERN MO. MAIN WARM FRONT
ACRS CENTRAL MN...FAR NORTHERN WI INTO THE NORTHERN LOWER MI.
SECONDARY FRONT ACRS WESTERN OK...AND REMNANT OUTFLOW BOUNDARY
ACRS CENTRAL MO ACTING AS BETTER SFC DPT POOLING MECHANISMS.
LOCALLY IN SOUTHWEST SFC FLOW...SFC DPTS HAVING TROUBLE GETTING
OUT OF THE LOWER 60S WITH FETCH BACK INTO SIMILAR AIR MASS IN
NORTHEASTERN KS/FAR NW MO. CUT-OFF UPPER LOW ALMOST STACKED OVER
SFC FEATURE...WITH WATER VAPOR IMAGERY INDICATING NOSE OF MID/UPPER
LEVEL SPEED MAX PUSHING ACRS NORTHEASTERN KS.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY MORNING)
ISSUED AT 248 PM CDT MON MAY 20 2013
TONIGHT...ASSESSING LOCAL INSTABILITY PARAMETERS...CAPES HAVE GROWN
TO ONLY 500 TO MAYBE 1000 J/KG ACRS PORTIONS OF THE DVN CWA...WITH
18Z SOUNDING SHOWING ROBUST H85 CAP/CONVECTIVE TEMP IN THE UPPER
80S. LACK OF AMBIENT CU LOCALLY A CLUE. DEEP UNIFORM SOUTHWESTERLIES
MAKING FOR MODERATE SHEAR/SPEED/ AT BEST. WITH MAIN VORT AND
MID/UPPER LEVEL VORT MAX STILL ACRS KS...DEEPER FORCING TO NOT
ARRIVE UNTIL MAINLY AFTER 00Z. THUS REST OF THIS AFTERNOON MAY SEE
A LACK OF CONVECTIVE ACTIVITY. WITH DEEP CONVECTIVE INDICE MAX
REALIGNING ACRS EASTERN KS INTO WESTERN/NORTHWEST MO THE REST OF THIS
AFTERNOON AND EARLY EVENING...EXPECT STORM DEVELOPMENT IN THESE
AREAS TO MOVE NORTHEAST AND BE THE SCTRD STORMS TO AFFECT PORTIONS
OF THE CWA THIS EVENING. THIS AND POSSIBLY SOME DEVELOPMENT AHEAD
OF THE WESTERN IA FRONT IN CU FIELD ONGOING OUT THERE ATTM. BUT
WITH YET UNFAVORABLE AIRMASS IN PLACE TO SUPPORT STRONG
CONVECTION...THIS ACTIVITY MAY WEAKEN AS IT ARRIVES UNLESS SOME
THERMODYNAMIC SUPPORT IS ADVECTED INTO THE AREA FROM THE
SOUTHWEST. MUCH UNCERTAINTY REGARDING THIS ATTM. IF STORMS DO
MAINTAIN AND MAKE IT INTO THE AREA...STILL A CHANCE FOR SOME SVR
CELLS LOOKING AT CURRENT AND PROGGED SHEAR PROFILES BUT MAIN
THREATS WOULD BE LARGE HAIL AND DAMAGING WIND GUSTS WITH ANY LINER/BOWING
DEVELOPMENT IN UNIFORM VERTICAL WIND FIELDS. LLVL SHEAR DIRECTION
AND HIGHER LCL/S OF AT LEAST 3K FT AGL CURRENTLY NOT THAT CONDUCIVE
FOR TORNADIC DEVELOPMENT. WILL KNOCK DOWN 00Z-06Z COVERAGE TO HIGH
CHC AND LIKELY POPS ACRS MOST OF THE DVN CWA...THEN WALK OUT ANY
LINGERING ACTIVITY AFTER 08Z FROM THE EASTERN CWA. LOCALLY HEAVY
RAINFALL BURSTS POSSIBLE...BUT MOVEMENT OF STORMS HOPEFULLY WILL
PRECLUDE MUCH OF ANY FLASH FLOOD THREAT UNLESS THE SAME AREA GETS
HIT REPEATEDLY AND HAD SIGNIFICANT RAIN LAST NIGHT. LOWS MAY DIP
INTO THE UPPER 50S IN THE NORTHWESTERN FCST AREA...BUT HELD IN THE
60S ELSEWHERE. ..12..
.LONG TERM...(TUESDAY THROUGH NEXT MONDAY) ISSUED AT 248 PM CDT
MON MAY 20 2013
UPPER LOW OVER THE NORTHERN PLAINS TO GRADUALLY FILL AND SHIFT
EASTWARD THROUGH MIDWEEK...REPLACED BY HIGH PRESSURE AT THE SURFACE
AND MID LEVEL RIDGING. THIS WILL PROVIDE A CHANGE TO BELOW NORMAL
TEMPERATURES AND DRY WEATHER BY LATE WEEK. OVER THE WEEKEND...A
COOLER...UNSETTLED PATTERN DEVELOPS AS RETURNING MOISTURE INTERACTS
WITH A BOUNDARY OVER THE AREA.
TUESDAY...SURFACE LOW GRADUALLY EJECTS EASTWARD INTO THE UPPER MS
VALLEY. THIS WILL SEND THE OCCLUDED FRONT EASTWARD THROUGH THE
FORECAST AREA IN THE MORNING...THEN A SECONDARY TROUGH IS INDICATED
BY THE NAM DURING PEAK HEATING. EACH OF THESE FEATURES WILL POSSIBLY
TRIGGER SHOWERS AND THUNDERSTORMS...BUT WITH LOW CONFIDENCE IN
THE TIMING...STRENGTH...OR AVAILABLE INSTABILITY WITH THESE
FEATURES...HAVE ONLY CHANCE POPS THROUGH THE DAY. SUPPORT FOR SEVERE
STORMS IS LACKING DUE TO LESS FAVORABLE SHEAR PROFILES AND LIKELY
LESS AVAILABLE INSTABILITY THAN THE PAST COUPLE DAYS. COOLER
TEMPERATURES AT 850 MB AND LIKELIHOOD OF MORE CLOUDS SHOULD LIMIT
HIGHS TO THE MID 70S WEST TO POSSIBLY MID 80S EAST.
TUESDAY NIGHT INTO WED...SURFACE LOW TRANSITIONING EASTWARD INTO THE
GREAT LAKES AND FILLING UPPER LOW MIGRATING OVERHEAD TO KEEP
CHANCES FOR MAINLY DIURNAL SHOWERS GOING WITH HIGHEST POPS IN THE
EAST. ADVECTION OF COOLER... DRIER AIR TO ALLOW MINS TO COOL INTO
THE 50S WITH WED HIGHS LIMITED TO THE UPPER 60S TO LOWER 70S.
THURSDAY AND FRIDAY...UPPER TROUGH ADVANCES EASTWARD ALLOWING
CANADIAN HIGH PRESSURE TO BUILD SOUTHEAST INTO THE GREAT LAKES.
HAVE TWEAKED TEMPERATURES DOWNWARD SOME TO LIMIT HIGHS TO THE 60S
AND POSSIBLY LOWER 70S FOR FRI...WHILE LOWS THURSDAY NIGHT SHOULD BE
WIDESPREAD IN THE 40S AS THE CENTER OF THE INCOMING RIDGE PASSES
OVERHEAD.
SATURDAY THROUGH MONDAY REMAINS A BELOW AVERAGE CONFIDENCE FORECAST
PERIOD AS THERE IS LITTLE AGREEMENT IN THE DETAILS OF RETURN
WARM...MOIST ADVECTION FLOW...THE ASSOCIATED BOUNDARY...AND WHERE
PRECIPITATION WILL SET UP. FOR NOW...A BLENDED APPROACH TO DIVERSE
SOLUTIONS WILL KEEP AN EXTENDED PERIOD OF CHANCE POPS WITH
TEMPERATURES GRADUALLY WARMING TO NEAR OR ABOVE NORMAL BY MONDAY
WHEN THE ODDS ARE GREATER THAT THE FRONT WILL HAVE LIFTED NORTH OF
THE AREA. SHEETS
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 1232 AM CDT TUE MAY 21 2013
FEW SHOWERS AND ISOLD STORM CURRENTLY OVER EASTERN IOWA AND WILL
REMAIN POSSIBLE REST OF OVERNIGHT UNTIL MID AM TUE...BUT
CONFIDENCE TOO LOW FOR INCLUSION AT TERMINALS ASIDE FROM KDBQ
WHERE VCSH NEXT COUPLE OF HOURS. SOME PATCHY FOG POSSIBLE
ESPECIALLY IN AREAS THAT RECEIVED RAINFALL PAST 12 HRS...WHICH
INCLUDES KBRL. HAVE OPTED FOR TEMPO OF MVFR VSBYS AT KBRL AROUND
SUNRISE. OTHERWISE... KEPT REST OF THE TAF CYCLE DRY ALTHOUGH
CANT RULE OUT SOME PCPN ESPECIALLY EAST OF THE TERMINALS BY MID TO
LATE AFTERNOON DEVELOPING AHEAD OF PLAINS UPPER LOW AS IT DRIFTS
SLOWLY INTO THE UPPER MIDWEST. WINDS TO BECOME GUSTY FROM
SOUTHWEST TODAY AT 15 TO 25 KTS...THEN DIMINISH BELOW 10 KTS
TOWARD SUNSET AND MAY BECOME LIGHT AND VARIABLE.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...12
SHORT TERM...12
LONG TERM...SHEETS
AVIATION...05
000
FXUS63 KDMX 210030
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
730 PM CDT MON MAY 20 2013
.SHORT TERM.../TONIGHT /...
ISSUED AT 314 PM CDT MON MAY 20 2013
MAIN CONCERNS WILL BE THE CHANCES FOR SEVERE WEATHER. THOUGH WE
HAVE SUFFICIENT CAPE AND BULK SHEAR PRESENTLY...THERE IS LITTLE
SFC CONVERGENCE IN THE AREAS OF HIGHEST INSTABILITY. THE CHANCE
YET THIS EVENING IS CONDITIONAL AND WITH THE BETTER CHANCES STILL
OVER THE SOUTHEAST. WITH THE LESSENING OF DAYTIME HEATING AND
SUNSET... THE THREAT WILL DIMINISH THIS EVENING. OVERNIGHT LOWS
WILL DROP INTO INTO THE 50S NORTHWEST AND THE LOWER 60S IN THE
SOUTHEAST. WINDS WILL DIMINISH THIS EVENING AS WELL.
.LONG TERM.../TUESDAY THROUGH MONDAY/...
ISSUED AT 314 PM CDT MON MAY 20 2013
MAIN FORECAST CONCERN WAS FOCUSED ON STUBBORN UPPER LOW TO SLOWLY
MIGRATE EAST TUESDAY AND WEDNESDAY. MODELS ARE IN GREAT AGREEMENT
WITH PLACING THE FORECAST AREA IN MUCH OF THE DRY SLOT TUESDAY
INTO WEDNESDAY...THEN WITH THE COOL DOWN LATE IN THE WEEK. LEANED
TOWARD A NAM/GFS/SREF BLEND THROUGH WEDNESDAY...AND MORE TOWARDS
THE ECMWF BY THE WEEKEND. GFS SEEMED TOO COLD FOR THURSDAY AND
FRIDAY.
.TUESDAY AND WEDNESDAY...
UPPER LOW CONTINUES OVER SOUTHERN MINNESOTA BEFORE BEGINNING TO
SHIFT EAST INTO NORTHERN IOWA BY 12Z WEDNESDAY. THE BULK OF THE
MOISTURE AND BEST DYNAMICS FOR STORM DEVELOPMENT REMAINS EAST OF
THE FORECAST AREA ALONG THE COLD FRONT IN ILLINOIS AND MISSOURI.
LOW CONFIDENCE WITH MUCH CONVECTION OVER CENTRAL TO WESTERN
PORTIONS OF THE FORECAST AREA...AND KEPT SMALL POPS GOING IN THE
EAST MAINLY DUE TO SOME WEAK INSTABILITY BY THE AFTERNOON. WRAP-
AROUND MOISTURE WITHIN THE CAA REGIME BEHIND THE SURFACE LOW
TRACKING ACROSS NORTHERN IOWA WILL PROVIDE SOME SHOWER ACTIVITY
WEDNESDAY OVER THE FORECAST AREA.
.THURSADY THROUGH MONDAY...
SURFACE HIGH BUILDS INTO THE REGION THURSDAY AND CONTINUES THROUGH
AT LEAST FRIDAY. TEMPS AND DEW POINTS LOOK TO REMAIN FAIRLY
PLEASANT THURSDAY AND FRIDAY. DECENT THETA-E ADVECTION DEVELOPS BY
FRIDAY AFTERNOON ACROSS WESTERN IOWA AS A SHORTWAVE RIDES ALONG
THE 500MB RIDGE. ECMWF IS SLIGHTLY FASTER THAN THE GFS...BUT BEST
FORCING AND THETA-E ADVECTION MOVES INTO THE FORECAST AREA BY 00Z
SATURDAY. KEPT MUCH OF THE FORECAST AREA DRY ON FRIDAY. SERIES OF
SHORTWAVES CONTINUE TO RIDGE THE UPPER LEVEL RIDGE DURING THE
WEEKEND AND LOOK TO PROVIDE AN ACTIVE MEMORIAL WEEKEND.
&&
.AVIATION...21/00Z
ISSUED AT 730 PM CDT MON MAY 20 2013
CYCLONIC CIRCULATION OVER THE STATE HAS HELPED SET OFF
THUNDERSTORMS THIS EVENING. TWO MAIN LINES OVER NORTHWEST
IOWA...AND ALSO FROM SOUTHWEST IN TO CENTRAL IOWA. TSRA WILL
DISSIPATE BY AROUND 06Z WITH SCT-BKN MVFR CIGS AROUND THE STATE
LATE TONIGHT INTO TUE MORNING. VFR CONDITIONS EXPECTED TUE WITH
RE-DEVELOPMENT OF TSRA OVR THE ERN TAF SITES POSSIBLE.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...REV
LONG TERM...PODRAZIK
AVIATION...MS MAY 13
000
FXUS63 KDVN 202350
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
650 PM CDT MON MAY 20 2013
.SYNOPSIS...
ISSUED AT 248 PM CDT MON MAY 20 2013
LATEST SFC ANALYSIS WAS INDICATING OCCLUDING CYCLONE COMPLEX ACRS
THE EASTERN SD/ND REGION...WITH LEAD FRONT PUSHING ACRS WESTERN IA
BUT BETTER COLD WRAP AROUND NOTED ACRS SD INTO CENTRAL NEB. THE
REGION HAS BEEN PRETTY MUCH BATHED IN PRESSURE RISES TODAY...BUT
FALLS INCREASING ACRS WESTERN AND NORTHWESTERN MO. MAIN WARM FRONT
ACRS CENTRAL MN...FAR NORTHERN WI INTO THE NORTHERN LOWER MI.
SECONDARY FRONT ACRS WESTERN OK...AND REMNANT OUTFLOW BOUNDARY
ACRS CENTRAL MO ACTING AS BETTER SFC DPT POOLING MECHANISMS.
LOCALLY IN SOUTHWEST SFC FLOW...SFC DPTS HAVING TROUBLE GETTING
OUT OF THE LOWER 60S WITH FETCH BACK INTO SIMILAR AIR MASS IN
NORTHEASTERN KS/FAR NW MO. CUT-OFF UPPER LOW ALMOST STACKED OVER
SFC FEATURE...WITH WATER VAPOR IMAGERY INDICATING NOSE OF MID/UPPER
LEVEL SPEED MAX PUSHING ACRS NORTHEASTERN KS.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY MORNING)
ISSUED AT 248 PM CDT MON MAY 20 2013
TONIGHT...ASSESSING LOCAL INSTABILITY PARAMETERS...CAPES HAVE GROWN
TO ONLY 500 TO MAYBE 1000 J/KG ACRS PORTIONS OF THE DVN CWA...WITH
18Z SOUNDING SHOWING ROBUST H85 CAP/CONVECTIVE TEMP IN THE UPPER
80S. LACK OF AMBIENT CU LOCALLY A CLUE. DEEP UNIFORM SOUTHWESTERLIES
MAKING FOR MODERATE SHEAR/SPEED/ AT BEST. WITH MAIN VORT AND
MID/UPPER LEVEL VORT MAX STILL ACRS KS...DEEPER FORCING TO NOT
ARRIVE UNTIL MAINLY AFTER 00Z. THUS REST OF THIS AFTERNOON MAY SEE
A LACK OF CONVECTIVE ACTIVITY. WITH DEEP CONVECTIVE INDICE MAX
REALIGNING ACRS EASTERN KS INTO WESTERN/NORTHWEST MO THE REST OF THIS
AFTERNOON AND EARLY EVENING...EXPECT STORM DEVELOPMENT IN THESE
AREAS TO MOVE NORTHEAST AND BE THE SCTRD STORMS TO AFFECT PORTIONS
OF THE CWA THIS EVENING. THIS AND POSSIBLY SOME DEVELOPMENT AHEAD
OF THE WESTERN IA FRONT IN CU FIELD ONGOING OUT THERE ATTM. BUT
WITH YET UNFAVORABLE AIRMASS IN PLACE TO SUPPORT STRONG
CONVECTION...THIS ACTIVITY MAY WEAKEN AS IT ARRIVES UNLESS SOME
THERMODYNAMIC SUPPORT IS ADVECTED INTO THE AREA FROM THE
SOUTHWEST. MUCH UNCERTAINTY REGARDING THIS ATTM. IF STORMS DO
MAINTAIN AND MAKE IT INTO THE AREA...STILL A CHANCE FOR SOME SVR
CELLS LOOKING AT CURRENT AND PROGGED SHEAR PROFILES BUT MAIN
THREATS WOULD BE LARGE HAIL AND DAMAGING WIND GUSTS WITH ANY LINER/BOWING
DEVELOPMENT IN UNIFORM VERTICAL WIND FIELDS. LLVL SHEAR DIRECTION
AND HIGHER LCL/S OF AT LEAST 3K FT AGL CURRENTLY NOT THAT CONDUCIVE
FOR TORNADIC DEVELOPMENT. WILL KNOCK DOWN 00Z-06Z COVERAGE TO HIGH
CHC AND LIKELY POPS ACRS MOST OF THE DVN CWA...THEN WALK OUT ANY
LINGERING ACTIVITY AFTER 08Z FROM THE EASTERN CWA. LOCALLY HEAVY
RAINFALL BURSTS POSSIBLE...BUT MOVEMENT OF STORMS HOPEFULLY WILL
PRECLUDE MUCH OF ANY FLASH FLOOD THREAT UNLESS THE SAME AREA GETS
HIT REPEATEDLY AND HAD SIGNIFICANT RAIN LAST NIGHT. LOWS MAY DIP
INTO THE UPPER 50S IN THE NORTHWESTERN FCST AREA...BUT HELD IN THE
60S ELSEWHERE. ..12..
.LONG TERM...(TUESDAY THROUGH NEXT MONDAY) ISSUED AT 248 PM CDT
MON MAY 20 2013
UPPER LOW OVER THE NORTHERN PLAINS TO GRADUALLY FILL AND SHIFT
EASTWARD THROUGH MIDWEEK...REPLACED BY HIGH PRESSURE AT THE SURFACE
AND MID LEVEL RIDGING. THIS WILL PROVIDE A CHANGE TO BELOW NORMAL
TEMPERATURES AND DRY WEATHER BY LATE WEEK. OVER THE WEEKEND...A
COOLER...UNSETTLED PATTERN DEVELOPS AS RETURNING MOISTURE INTERACTS
WITH A BOUNDARY OVER THE AREA.
TUESDAY...SURFACE LOW GRADUALLY EJECTS EASTWARD INTO THE UPPER MS
VALLEY. THIS WILL SEND THE OCCLUDED FRONT EASTWARD THROUGH THE
FORECAST AREA IN THE MORNING...THEN A SECONDARY TROUGH IS INDICATED
BY THE NAM DURING PEAK HEATING. EACH OF THESE FEATURES WILL POSSIBLY
TRIGGER SHOWERS AND THUNDERSTORMS...BUT WITH LOW CONFIDENCE IN
THE TIMING...STRENGTH...OR AVAILABLE INSTABILITY WITH THESE
FEATURES...HAVE ONLY CHANCE POPS THROUGH THE DAY. SUPPORT FOR SEVERE
STORMS IS LACKING DUE TO LESS FAVORABLE SHEAR PROFILES AND LIKELY
LESS AVAILABLE INSTABILITY THAN THE PAST COUPLE DAYS. COOLER
TEMPERATURES AT 850 MB AND LIKELIHOOD OF MORE CLOUDS SHOULD LIMIT
HIGHS TO THE MID 70S WEST TO POSSIBLY MID 80S EAST.
TUESDAY NIGHT INTO WED...SURFACE LOW TRANSITIONING EASTWARD INTO THE
GREAT LAKES AND FILLING UPPER LOW MIGRATING OVERHEAD TO KEEP
CHANCES FOR MAINLY DIURNAL SHOWERS GOING WITH HIGHEST POPS IN THE
EAST. ADVECTION OF COOLER... DRIER AIR TO ALLOW MINS TO COOL INTO
THE 50S WITH WED HIGHS LIMITED TO THE UPPER 60S TO LOWER 70S.
THURSDAY AND FRIDAY...UPPER TROUGH ADVANCES EASTWARD ALLOWING
CANADIAN HIGH PRESSURE TO BUILD SOUTHEAST INTO THE GREAT LAKES.
HAVE TWEAKED TEMPERATURES DOWNWARD SOME TO LIMIT HIGHS TO THE 60S
AND POSSIBLY LOWER 70S FOR FRI...WHILE LOWS THURSDAY NIGHT SHOULD BE
WIDESPREAD IN THE 40S AS THE CENTER OF THE INCOMING RIDGE PASSES
OVERHEAD.
SATURDAY THROUGH MONDAY REMAINS A BELOW AVERAGE CONFIDENCE FORECAST
PERIOD AS THERE IS LITTLE AGREEMENT IN THE DETAILS OF RETURN
WARM...MOIST ADVECTION FLOW...THE ASSOCIATED BOUNDARY...AND WHERE
PRECIPITATION WILL SET UP. FOR NOW...A BLENDED APPROACH TO DIVERSE
SOLUTIONS WILL KEEP AN EXTENDED PERIOD OF CHANCE POPS WITH
TEMPERATURES GRADUALLY WARMING TO NEAR OR ABOVE NORMAL BY MONDAY
WHEN THE ODDS ARE GREATER THAT THE FRONT WILL HAVE LIFTED NORTH OF
THE AREA. SHEETS
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING)
ISSUED AT 644 PM CDT MON MAY 20 2013
MAIN CONCERN FOR TAFS IN THE NEXT 24 HOURS IS THUNDERSTORM CHANCES
TONIGHT. LOOK LIKE TWO CENTERS OF ACTION...CLUSTERS IN NORTHWEST
MISSOURI WHICH LOOK IN LINE TO IMPACT BRL AND MLI...AND ANOTHER IN
CENTRAL IOWA WHICH WOULD APPEAR HEADED NORTH AND WEST OF CID AND
DBQ AT THIS TIME. COLD FRONTAL PASSAGE PROGGED TOMORROW WILL
RESULT IN GRADUAL SHIFTING OF WIND FROM SOUTH TO WEST. WOLF
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...12
SHORT TERM...12
LONG TERM...SHEETS
AVIATION...WOLF
000
FXUS63 KDMX 202046
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
346 PM CDT MON MAY 20 2013
.SHORT TERM.../TONIGHT /...
ISSUED AT 314 PM CDT MON MAY 20 2013
MAIN CONCERNS WILL BE THE CHANCES FOR SEVERE WEATHER. THOUGH WE
HAVE SUFFICIENT CAPE AND BULK SHEAR PRESENTLY...THERE IS LITTLE
SFC CONVERGENCE IN THE AREAS OF HIGHEST INSTABILITY. THE CHANCE
YET THIS EVENING IS CONDITIONAL AND WITH THE BETTER CHANCES STILL
OVER THE SOUTHEAST. WITH THE LESSENING OF DAYTIME HEATING AND
SUNSET... THE THREAT WILL DIMINISH THIS EVENING. OVERNIGHT LOWS
WILL DROP INTO INTO THE 50S NORTHWEST AND THE LOWER 60S IN THE
SOUTHEAST. WINDS WILL DIMINISH THIS EVENING AS WELL.
.LONG TERM.../TUESDAY THROUGH MONDAY/...
ISSUED AT 314 PM CDT MON MAY 20 2013
MAIN FORECAST CONCERN WAS FOCUSED ON STUBBORN UPPER LOW TO SLOWLY
MIGRATE EAST TUESDAY AND WEDNESDAY. MODELS ARE IN GREAT AGREEMENT
WITH PLACING THE FORECAST AREA IN MUCH OF THE DRY SLOT TUESDAY
INTO WEDNESDAY...THEN WITH THE COOL DOWN LATE IN THE WEEK. LEANED
TOWARD A NAM/GFS/SREF BLEND THROUGH WEDNESDAY...AND MORE TOWARDS
THE ECMWF BY THE WEEKEND. GFS SEEMED TOO COLD FOR THURSDAY AND
FRIDAY.
.TUESDAY AND WEDNESDAY...
UPPER LOW CONTINUES OVER SOUTHERN MINNESOTA BEFORE BEGINNING TO
SHIFT EAST INTO NORTHERN IOWA BY 12Z WEDNESDAY. THE BULK OF THE
MOISTURE AND BEST DYNAMICS FOR STORM DEVELOPMENT REMAINS EAST OF
THE FORECAST AREA ALONG THE COLD FRONT IN ILLINOIS AND MISSOURI.
LOW CONFIDENCE WITH MUCH CONVECTION OVER CENTRAL TO WESTERN
PORTIONS OF THE FORECAST AREA...AND KEPT SMALL POPS GOING IN THE
EAST MAINLY DUE TO SOME WEAK INSTABILITY BY THE AFTERNOON. WRAP-
AROUND MOISTURE WITHIN THE CAA REGIME BEHIND THE SURFACE LOW
TRACKING ACROSS NORTHERN IOWA WILL PROVIDE SOME SHOWER ACTIVITY
WEDNESDAY OVER THE FORECAST AREA.
.THURSADY THROUGH MONDAY...
SURFACE HIGH BUILDS INTO THE REGION THURSDAY AND CONTINUES THROUGH
AT LEAST FRIDAY. TEMPS AND DEW POINTS LOOK TO REMAIN FAIRLY
PLEASANT THURSDAY AND FRIDAY. DECENT THETA-E ADVECTION DEVELOPS BY
FRIDAY AFTERNOON ACROSS WESTERN IOWA AS A SHORTWAVE RIDES ALONG
THE 500MB RIDGE. ECMWF IS SLIGHTLY FASTER THAN THE GFS...BUT BEST
FORCING AND THETA-E ADVECTION MOVES INTO THE FORECAST AREA BY 00Z
SATURDAY. KEPT MUCH OF THE FORECAST AREA DRY ON FRIDAY. SERIES OF
SHORTWAVES CONTINUE TO RIDGE THE UPPER LEVEL RIDGE DURING THE
WEEKEND AND LOOK TO PROVIDE AN ACTIVE MEMORIAL WEEKEND.
&&
.AVIATION...20/18Z
ISSUED AT 1222 PM CDT MON MAY 20 2013
PRIMARY CONCERNS ARE WINDS AND TIMING OF CONVECTION THIS AFTERNOON
AND EVENING. PREVIOUS TIMING LOOKS GOOD WITH SOME SCT ACTIVITY
DEVELOPING IN THE AFTERNOON/EVENING HOURS UNTIL INSTABILITY
LESSENS. AREA OF CLOUDS OVER NORTHERN IOWA MVFR AND WILL CONTINUE
TO HOLD ON AS AREA MOVES EAST NORTHEAST. SHOWERS SHOULD DEVELOP
NORTHWEST AS WELL. WINDS PICK UP AGAIN TUESDAY AFTER MIXING BEGINS
AROUND 14 TO 15Z.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...REV
LONG TERM...PODRAZIK
AVIATION...REV
000
FXUS63 KDVN 202026
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
326 PM CDT MON MAY 20 2013
.SYNOPSIS...
ISSUED AT 248 PM CDT MON MAY 20 2013
LATEST SFC ANALYSIS WAS INDICATING OCCLUDING CYCLONE COMPLEX ACRS
THE EASTERN SD/ND REGION...WITH LEAD FRONT PUSHING ACRS WESTERN IA
BUT BETTER COLD WRAP AROUND NOTED ACRS SD INTO CENTRAL NEB. THE
REGION HAS BEEN PRETTY MUCH BATHED IN PRESSURE RISES TODAY...BUT
FALLS INCREASING ACRS WESTERN AND NORTHWESTERN MO. MAIN WARM FRONT
ACRS CENTRAL MN...FAR NORTHERN WI INTO THE NORTHERN LOWER MI.
SECONDARY FRONT ACRS WESTERN OK...AND REMNANT OUTFLOW BOUNDARY
ACRS CENTRAL MO ACTING AS BETTER SFC DPT POOLING MECHANISMS.
LOCALLY IN SOUTHWEST SFC FLOW...SFC DPTS HAVING TROUBLE GETTING
OUT OF THE LOWER 60S WITH FETCH BACK INTO SIMILAR AIR MASS IN
NORTHEASTERN KS/FAR NW MO. CUT-OFF UPPER LOW ALMOST STACKED OVER
SFC FEATURE...WITH WATER VAPOR IMAGERY INDICATING NOSE OF MID/UPPER
LEVEL SPEED MAX PUSHING ACRS NORTHEASTERN KS.
&&
.SHORT TERM...(THIS EVENING THROUGH TUESDAY MORNING)
ISSUED AT 248 PM CDT MON MAY 20 2013
TONIGHT...ASSESSING LOCAL INSTABILITY PARAMETERS...CAPES HAVE GROWN
TO ONLY 500 TO MAYBE 1000 J/KG ACRS PORTIONS OF THE DVN CWA...WITH
18Z SOUNDING SHOWING ROBUST H85 CAP/CONVECTIVE TEMP IN THE UPPER
80S. LACK OF AMBIENT CU LOCALLY A CLUE. DEEP UNIFORM SOUTHWESTERLIES
MAKING FOR MODERATE SHEAR/SPEED/ AT BEST. WITH MAIN VORT AND
MID/UPPER LEVEL VORT MAX STILL ACRS KS...DEEPER FORCING TO NOT
ARRIVE UNTIL MAINLY AFTER 00Z. THUS REST OF THIS AFTERNOON MAY SEE
A LACK OF CONVECTIVE ACTIVITY. WITH DEEP CONVECTIVE INDICE MAX
REALIGNING ACRS EASTERN KS INTO WESTERN/NORTHWEST MO THE REST OF THIS
AFTERNOON AND EARLY EVENING...EXPECT STORM DEVELOPMENT IN THESE
AREAS TO MOVE NORTHEAST AND BE THE SCTRD STORMS TO AFFECT PORTIONS
OF THE CWA THIS EVENING. THIS AND POSSIBLY SOME DEVELOPMENT AHEAD
OF THE WESTERN IA FRONT IN CU FIELD ONGOING OUT THERE ATTM. BUT
WITH YET UNFAVORABLE AIRMASS IN PLACE TO SUPPORT STRONG
CONVECTION...THIS ACTIVITY MAY WEAKEN AS IT ARRIVES UNLESS SOME
THERMODYNAMIC SUPPORT IS ADVECTED INTO THE AREA FROM THE
SOUTHWEST. MUCH UNCERTAINTY REGARDING THIS ATTM. IF STORMS DO
MAINTAIN AND MAKE IT INTO THE AREA...STILL A CHANCE FOR SOME SVR
CELLS LOOKING AT CURRENT AND PROGGED SHEAR PROFILES BUT MAIN
THREATS WOULD BE LARGE HAIL AND DAMAGING WIND GUSTS WITH ANY LINER/BOWING
DEVELOPMENT IN UNIFORM VERTICAL WIND FIELDS. LLVL SHEAR DIRECTION
AND HIGHER LCL/S OF AT LEAST 3K FT AGL CURRENTLY NOT THAT CONDUCIVE
FOR TORNADIC DEVELOPMENT. WILL KNOCK DOWN 00Z-06Z COVERAGE TO HIGH
CHC AND LIKELY POPS ACRS MOST OF THE DVN CWA...THEN WALK OUT ANY
LINGERING ACTIVITY AFTER 08Z FROM THE EASTERN CWA. LOCALLY HEAVY
RAINFALL BURSTS POSSIBLE...BUT MOVEMENT OF STORMS HOPEFULLY WILL
PRECLUDE MUCH OF ANY FLASH FLOOD THREAT UNLESS THE SAME AREA GETS
HIT REPEATEDLY AND HAD SIGNIFICANT RAIN LAST NIGHT. LOWS MAY DIP
INTO THE UPPER 50S IN THE NORTHWESTERN FCST AREA...BUT HELD IN THE
60S ELSEWHERE. ..12..
.LONG TERM...(TUESDAY THROUGH NEXT MONDAY) ISSUED AT 248 PM CDT
MON MAY 20 2013
UPPER LOW OVER THE NORTHERN PLAINS TO GRADUALLY FILL AND SHIFT
EASTWARD THROUGH MIDWEEK...REPLACED BY HIGH PRESSURE AT THE SURFACE
AND MID LEVEL RIDGING. THIS WILL PROVIDE A CHANGE TO BELOW NORMAL
TEMPERATURES AND DRY WEATHER BY LATE WEEK. OVER THE WEEKEND...A
COOLER...UNSETTLED PATTERN DEVELOPS AS RETURNING MOISTURE INTERACTS
WITH A BOUNDARY OVER THE AREA.
TUESDAY...SURFACE LOW GRADUALLY EJECTS EASTWARD INTO THE UPPER MS
VALLEY. THIS WILL SEND THE OCCLUDED FRONT EASTWARD THROUGH THE
FORECAST AREA IN THE MORNING...THEN A SECONDARY TROUGH IS INDICATED
BY THE NAM DURING PEAK HEATING. EACH OF THESE FEATURES WILL POSSIBLY
TRIGGER SHOWERS AND THUNDERSTORMS...BUT WITH LOW CONFIDENCE IN
THE TIMING...STRENGTH...OR AVAILABLE INSTABILITY WITH THESE
FEATURES...HAVE ONLY CHANCE POPS THROUGH THE DAY. SUPPORT FOR SEVERE
STORMS IS LACKING DUE TO LESS FAVORABLE SHEAR PROFILES AND LIKELY
LESS AVAILABLE INSTABILITY THAN THE PAST COUPLE DAYS. COOLER
TEMPERATURES AT 850 MB AND LIKELIHOOD OF MORE CLOUDS SHOULD LIMIT
HIGHS TO THE MID 70S WEST TO POSSIBLY MID 80S EAST.
TUESDAY NIGHT INTO WED...SURFACE LOW TRANSITIONING EASTWARD INTO THE
GREAT LAKES AND FILLING UPPER LOW MIGRATING OVERHEAD TO KEEP
CHANCES FOR MAINLY DIURNAL SHOWERS GOING WITH HIGHEST POPS IN THE
EAST. ADVECTION OF COOLER... DRIER AIR TO ALLOW MINS TO COOL INTO
THE 50S WITH WED HIGHS LIMITED TO THE UPPER 60S TO LOWER 70S.
THURSDAY AND FRIDAY...UPPER TROUGH ADVANCES EASTWARD ALLOWING
CANADIAN HIGH PRESSURE TO BUILD SOUTHEAST INTO THE GREAT LAKES.
HAVE TWEAKED TEMPERATURES DOWNWARD SOME TO LIMIT HIGHS TO THE 60S
AND POSSIBLY LOWER 70S FOR FRI...WHILE LOWS THURSDAY NIGHT SHOULD BE
WIDESPREAD IN THE 40S AS THE CENTER OF THE INCOMING RIDGE PASSES
OVERHEAD.
SATURDAY THROUGH MONDAY REMAINS A BELOW AVERAGE CONFIDENCE FORECAST
PERIOD AS THERE IS LITTLE AGREEMENT IN THE DETAILS OF RETURN
WARM...MOIST ADVECTION FLOW...THE ASSOCIATED BOUNDARY...AND WHERE
PRECIPITATION WILL SET UP. FOR NOW...A BLENDED APPROACH TO DIVERSE
SOLUTIONS WILL KEEP AN EXTENDED PERIOD OF CHANCE POPS WITH
TEMPERATURES GRADUALLY WARMING TO NEAR OR ABOVE NORMAL BY MONDAY
WHEN THE ODDS ARE GREATER THAT THE FRONT WILL HAVE LIFTED NORTH OF
THE AREA. SHEETS
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1243 PM CDT MON MAY 20 2013
HAVE PUSHED BACK STORM DEVELOPMENT TIME AT CID AND DBQ TIL LATE
AFTERNOON...BRL AND MLI TO 20Z TO 21Z. BUT SOME SIGNS MOST OF THE
TERMINALS WILL BE VFR THROUGH 00Z IF STORM CLUSTERS DON/T DEVELOP
OUT OF NORTHEAST MO OR SOUTHEASTERN IA THIS AFTERNOON AND THEN
MOVE TOWARD BRL AND MLI. IF AFTERNOON STORMS DON/T DEVELOP OR STAY
SOUTH/EAST OF THE TERMINALS...BEST CHANCE WILL COME LATER THIS
EVENING AFTER 01Z AS MAIN FRONT APPROACHES FROM THE WEST. THESE
STORMS COULD BE STRONG TO SVR TOO WITH DAMAGING WIND AND HAIL...BUT
ADEQUATE INSTABILITY QUESTIONS FOR BOTH THIS AFTERNOON AND EVENING
CONTINUE WITH SFC DPTS STRUGGLING TO GET OUT OF THE LOWER 60S.
OTHERWISE GOOD VISIBILITY THIS AFTERNOON WITH MAINLY CLR SKIES OR
HIGH CLOUD BLOW OFF FROM STORMS IN MO. SOUTHWEST WINDS AT 10 TO 20
KTS WITH SOME HIGHER GUSTS...TO BECOME SOUTH SOUTHWEST OVERNIGHT
WITHOUT THE GUSTS. BUT STILL A CHANCE FOR VARIABLE GUSTS OVER
35-40 KTS WITH THE EVENING LINE OF STORMS. SOME MVFR FOG POSSIBLE
TOWARD SUNRISE BEFORE SOUTHWEST WINDS INCREASE AGAIN BY MID TUE MORNING.
12
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...12
SHORT TERM...12
LONG TERM...SHEETS
AVIATION...12
000
FXUS63 KDVN 201754
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1254 PM CDT MON MAY 20 2013
.UPDATE...
ISSUED AT 1104 AM CDT MON MAY 20 2013
QUICK ASSESSMENT ON THIS MORNINGS UPPER AIR ANALYSIS AND WHAT IS
TAKING PACE CURRENTLY...SEEMS THERE MAY BE A DELAY TO LATER THIS
AFTERNOON AND EARLY EVENING. CURRENT TEMPS IN THE LOW TO MID 70S
WITH SFC DPTS MAINLY IN THE LOW 60S WILL STILL TAKE TIME TO
IMPROVE UPON...ESPECIALLY WITH BETTER SFC MOISTURE POOLED ALONG
OUTFLOW BOUNDARY ACRS CENTRAL MO ATTM. THE LOCAL AREA UNDER A H85
MB AND H7 MB LULL IN MOISTURE AS WELL. MID AND UPPER JET MAX/S
ACRS THE GRT BSN AND SHIFTING INTO THE SOUTHWESTERN PLAINS THIS
MORNING WILL NOT NOSE UP ACRS THE CWA UNTIL AFTER 20Z-21Z THIS
AFTERNOON. IF SFC DPTS ONLY RECOVER INTO THE MID 60S...THE 12Z NAM
AND GFS PROGGED CAPES OF 1500-2000 J/KG MAY BE TOO HIGH. ALSO HIGH
TEMPS MAY BE MORE IN THE WAY OF LOW TO MID 80S AS OPPOSED TO MID
TO UPPER 80S THIS AFTERNOON. SFC WINDS CURRENTLY SOUTH AND MAINLY
SOUTHWESTERLY...THUS WITHOUT AND LLVL BACKING TO THE SOUTHEAST THE
LOWER LEVEL HELICITIES AND SHEAR DON/T APPEAR AS IMPRESSIVE AS
WHAT MAY BE EARLIER THOUGHT. BUT THERE APPEARS TO BE DECENT DEEPER
LAYER SPEED SHEAR WITH UNIFORM VERTICAL PROFILES. LCL LEVELS MAY
NOT BE AS LOW AS WHAT THE SHORT RANGE MODELS DEPICT IN THE
SOUTHEAST THIRD/1500-2000 FT AGL/ THIS AFTERNOON AS WELL LIMITING
A POSSIBLE TORNADIC THREAT. THUS ALL IN ALL...LESS INSTABILITY
BUT STILL STRONG KINEMATICS/SHEAR SUGGEST A THREAT FOR LARGE HAIL
AND DAMAGING DOWNBURST WINDS WITH STILL THE POSSIBILITY OF
SUPERCELL TYPE DISCRETE STORMS THIS AFTERNOON...BUT MAY BE LESS
WIDESPREAD THEN YESTERDAY. THE SOUTHEAST THIRD OF THE CWA MOST AT
RISK OF SVR STORMS THIS AFTERNOON. STILL CAN/T RULE OUT ISOLATED
TORNADOES AND ANY WATCH THAT DOES COME OUT WILL PROBABLY STILL BE
A TOR WATCH FOR THE LOCAL AREA. SECOND ROUND OF STORMS ALONG THE
MAIN FRONT ITSELF...CURRENTLY ACRS FAR WESTERN IA...MAY SWEEP ACRS
THE AREA FROM THE WEST NOT UNTIL MID EVENING. WILL STILL HAVE TO
BE VERY MUCH ON GUARD AND WATCH TRENDS THROUGH THE AFTERNOON.
12
&&
.SYNOPSIS...
ISSUED AT 304 AM CDT MON MAY 20 2013
06Z SFC ANALYSIS HAS A SYNOPTIC LOW NEAR KMBG WITH THE STATIONARY
FRONT RUNNING EAST THROUGH WISCONSIN AND LOWER MICHIGAN. MESOSCALE
LOWS WERE NEAR KFSD...KBVN...AND KCSM. NUMEROUS OUTFLOW BOUNDARIES
RAN FROM ILLINOIS BACK THROUGH MISSOURI. DEW POINTS WERE IN THE 50S
AND 60S ACROSS THE MIDWEST.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 304 AM CDT MON MAY 20 2013
TODAY WILL BE QUITE INTERESTING. MESOSCALE PROCESSES WILL DRIVE THE
SENSIBLE WX AND CONCEPTUALLY...THERE IS A GOOD PROBABILITY OF SEEING
SEVERE STORMS THIS AFTERNOON AND EVENING.
MCS AND LIFT TOOLS SUGGEST THE BULK OF THE MCS MOVING ACROSS MISSOURI
WILL REMAIN SOUTH OF THE AREA. HOWEVER...VORT MAXES HELPING TO DRIVE
THIS MCS WILL PUSH DECAYING SHRA AND SOME TSRA INTO THE CWFA THROUGH
SUNRISE WITH ACTIVITY DISSIPATING DURING THE MORNING.
THERE SHOULD BE A FEW HOURS OF QUIET WX FROM MID TO LATE MORNING
UNTIL CONVECTIVE TEMPERATURE IS ACHIEVED. ONCE THIS OCCURS...NEW
CONVECTION WILL DEVELOP DURING THE AFTERNOON AND BUILD INTO ONE OR
MORE SEVERE MESOSCALE CONVECTIVE COMPLEXES BY EARLY EVENING.
THE OVERALL PLACEMENT OF THE JET STRUCTURE AND INSTABILITY AXIS
POINT TO SEVERE STORMS DEVELOPING DURING THE AFTERNOON. LARGE HAIL
AND DAMAGING WINDS ARE A GIVEN. THE SHEAR PROFILES AND BUOYANCY IS
ALSO FAVORABLE FOR TORNADOES...POSSIBLY SIGNIFICANT.
BY LATE EVENING AND OVERNIGHT...STORM ACTIVITY WILL BE ON THE
DECREASE AS THE ATMOSPHERE COOLS.
08
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 304 AM CDT MON MAY 20 2013
TURNING COOLER AND UNSETTLED WITH PROBABLY COOL RAINS AGAIN THIS NEXT
WEEKEND.
OVERVIEW...INITIALIZATION AND VERIFICATION ON LARGER SCALES...OR
SYNOPTIC SCALE ARE GOOD BUT ALL SOLUTIONS POOR TO VERY POOR ON
PRECIPITATION/MOISTURE/CLOUDS. AGAIN HEAVY USE OF CONCEPTUAL FORCING
TOOLS WHICH HAS AIDED PAST SEVERAL DAYS. THIS SUPPORTS MORE SHOWERS
AND STORMS TUESDAY TURNING COOLER WITH CLOUDS AND SHOWERS WEDNESDAY.
RISK OF SEVERE TUESDAY IS QUESTIONABLE BASED ON CONVECTION AND NEXT
WAVE INTERACTIONS LATER ON TUESDAY. PREFER A 60/40 MIX OF FORCING
OF HI-RES ECMWF AND NAM-WRF INTO DAY 4...THEN A 50/50 OF HI-RES
ECMWF AND GFS DAY 4 AND BEYOND.
TUESDAY...POOR CONFIDENCE IN FORECAST POPS AS NEXT 24 HOURS WILL
IMPACT EVOLUTION OF UPPER LOW AND PROGRESS OF COOL FRONT AND
ASSOCIATED AMOUNT OF CLEARING/CLOUDS. UPPER JET SUPPORTS LIGHTER AND
LOWER POPS WEST WITH RISK OF LINGERING WAVE OF SHOWERS AND STORMS
THAT SHOULD TEND TO STAY BELOW SEVERE LEVELS. HIGHS 75 TO 80 FROM
NW TO SE. MINS MID 50S NW TO THE LOWER 60S SE SECTIONS.
WEDNESDAY...CLOUDY AND COOLER WITH RAIN OR RAIN SHOWERS. HIGHS IN
THE NORTH MAY NEED LOWERING WITH LOW CLOUDS AND POSSIBLY EVEN
DRIZZLE WITH COOL NORTH WINDS ARRIVING FROM NORTH TO SOUTH DURING
THE DAY A BIT EARLIER IN THE FORECAST FOR LATER SHIFTS. WEDNESDAY
NIGHT...LOW CLOUDS AND POSSIBLY LIGHT RAIN AND PROBABLY AREAS OF
DRIZZLE WITH MINS IN THE 50S.
THURSDAY AND FRIDAY...BELOW NORMAL TEMPERATURES MOSTLY IN 65 TO
72 DEGREE RANGE. CLOUDS WILL CLEAR IN THE AFTERNOON FROM NORTH TO
SOUTH AS CANADIAN HIGH PRESSURE MOVES IN. THURSDAY NIGHT...CLEAR
AND COOL WITH MINS PROBABLY MANY LOCATIONS 3+ DEGREES TOO MILD WITH
LOWER TO MIDDLE 40S SUGGESTED OVER NORTH SECTIONS. FRIDAY...SUNNY
AND COOL WITH LIGHT NE WINDS.
SATURDAY AND SUNDAY...WESTERLY WINDS TO UPGLIDE OVER COOL AIRMASS
THAT PRIMES THE REGION FOR COOL HIGHS DUE TO GOOD EVAPORATIVE
COOLING AND LIKELY RAIN AND ISOLATED STORMS POSSIBLE IN SOUTH AND
WEST SECTIONS. CHANCE POPS FOR NOW WILL LIKELY BE RAISED WITH
TIMING ISSUES BETTER CLARIFIED. ANOTHER MODERATE TO LOCALLY LOWER
END HEAVY RAIN EVENT WITH MOST AREAS PICKING UP .5 TO 1+ INCHES.
NICHOLS
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1243 PM CDT MON MAY 20 2013
HAVE PUSHED BACK STORM DEVELOPMENT TIME AT CID AND DBQ TIL LATE
AFTERNOON...BRL AND MLI TO 20Z TO 21Z. BUT SOME SIGNS MOST OF THE
TERMINALS WILL BE VFR THROUGH 00Z IF STORM CLUSTERS DON/T DEVELOP
OUT OF NORTHEAST MO OR SOUTHEASTERN IA THIS AFTERNOON AND THEN
MOVE TOWARD BRL AND MLI. IF AFTERNOON STORMS DON/T DEVELOP OR STAY
SOUTH/EAST OF THE TERMINALS...BEST CHANCE WILL COME LATER THIS
EVENING AFTER 01Z AS MAIN FRONT APPROACHES FROM THE WEST. THESE
STORMS COULD BE STRONG TO SVR TOO WITH DAMAGING WIND AND HAIL...BUT
ADEQUATE INSTABILITY QUESTIONS FOR BOTH THIS AFTERNOON AND EVENING
CONTINUE WITH SFC DPTS STRUGGLING TO GET OUT OF THE LOWER 60S.
OTHERWISE GOOD VISIBILITY THIS AFTERNOON WITH MAINLY CLR SKIES OR
HIGH CLOUD BLOW OFF FROM STORMS IN MO. SOUTHWEST WINDS AT 10 TO 20
KTS WITH SOME HIGHER GUSTS...TO BECOME SOUTH SOUTHWEST OVERNIGHT
WITHOUT THE GUSTS. BUT STILL A CHANCE FOR VARIABLE GUSTS OVER
35-40 KTS WITH THE EVENING LINE OF STORMS. SOME MVFR FOG POSSIBLE
TOWARD SUNRISE BEFORE SOUTHWEST WINDS INCREASE AGAIN BY MID TUE MORNING.
12
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...12
SYNOPSIS...08
SHORT TERM...08
LONG TERM...NICHOLS
AVIATION...12
000
FXUS63 KDMX 201728
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1228 PM CDT MON MAY 20 2013
.UPDATE...
ISSUED AT 1222 PM CDT MON MAY 20 2013
LOWERED TMAX ACROSS THE NORTH FOR THE AFTERNOON AS CLOUDS HAVE
INCREASED MORE RAPIDLY THERE AND SHOWERS SHOULD DEVELOP LATER IN
THE AFTERNOON. DEW POINTS SLIGHTLY LOWER ACROSS EAST AND SOUTHEAST
AS WELL. TIMING OF POSSIBLE STORMS STILL LOOKS LIKE LATE AFTERNOON
OR EVENING SOUTHEAST INTO THE EVENING HOURS.
&&
.SHORT TERM.../TODAY /...
ISSUED AT 350 AM CDT MON MAY 20 2013
AREA OF SURFACE LOW PRESSURE OFF TO THE NORTHWEST ACROSS EASTERN
SD...WITH ASSOCIATED COLD FRONT STRETCHING SOUTHWARD ACROSS CENTRAL
NE INTO EXTREME NW KS. DRY SLOT CURRENTLY PUSHING THROUGH KS INTO
ERN NE...WILL CONTINUE TO PUSH ENE INTO IOWA THROUGH THE NEXT FEW
HOURS...WHICH SHOULD KEEP ANY PRECIP OFF TO THE SOUTHEAST THROUGH
SUNRISE POSSIBLY CLIPPING THE FAR SOUTHEASTERN CWA. OTHERWISE
ANOTHER VORT LOBE ROTATING AROUND THE UPPER LOW SITUATED OVER THE
WESTERN DAKOTAS WILL ROTATE THROUGH NORTHWEST IOWA THIS
MORNING...BRINGING THE POSSIBILITY OF SOME SHOWER/THUNDERSTORMS
TOWARD MID/LATE MORNING ACROSS THE FAR NORTHWESTERN CWA. REMAINDER
OF THE CWA SHOULD SEE MAINLY DRY CONDITIONS THROUGH MUCH OF THE
DAY...WITH SOUTHERLY FLOW AND MOISTURE CONTINUING TO PUSH BACK INTO
THE EASTERN CWA. SOUNDINGS INDICATING EASTERN CWA TO BECOME
DESTABILIZE AROUND 21-00Z WITH CAPE VALUES IN THE 1500 TO 2500 J/KG
AND SUFFICIENT DEEP LAYER SHEAR. THEREFORE HAVE POPS RETURNING THIS
AFTERNOON ACROSS THE REMAINDER OF THE CWA...WITH GREATEST CHANCE FOR
SEVERE WEATHER ALSO WITH THIS MID/LATE AFTERNOON ACTIVITY ACROSS THE
EAST/SOUTHEASTERN CWA.
TEMPERATURES EXPECTED TO BE A BIT COOLER TODAY WITH SLIGHTLY COOLER
AIRMASS ALOFT...WITH COOLEST TEMPS ACROSS THE NORTHWEST WHERE
CLOUDS/PRECIP CHANCES EXPECTED THROUGHOUT THE DAY. OVERALL HIGHS IN
THE 70S NORTH TO LOW/MID 80S SOUTH. SOUTHERLY WINDS TO BE BREEZY
AGAIN TODAY AS STRONGER WINDS ALOFT MIX TO THE SURFACE.
.LONG TERM.../TONIGHT THROUGH SATURDAY/...
ISSUED AT 350 AM CDT MON MAY 20 2013
CONVECTION WILL BE ONGOING THIS EVENING BUT WILL BE DEPARTING
QUICKLY TO THE NORTHEAST AS THE SHORTWAVE PASSES THROUGH THE
STATE. ANY SEVERE CONVECTION WILL LIKELY BE EARLY THIS EVENING IN
THE SOUTHEAST PRIOR TO MORE STABLE AIRMASS AND PRECIPITATION
DEPARTURE BY LATE EVENING. AFTER MIDNIGHT TONIGHT...MUCH OF THE
AREA SHOULD SEE LITTLE IF ANY RAINFALL AS DRIER AIR ENTERS THE
STATE AND SUBSIDENCE INCREASES...ESPECIALLY IN THE SOUTH. MUCH OF
TUESDAY ALSO APPEARS DRY ALTHOUGH SOME AFTERNOON REDEVELOPMENT
REMAIN POSSIBLE AS UPPER LOW SLIPS TOWARD THE STATE. THIS LOW WILL
SLIDE ACROSS NORTHERN IOWA ON WEDNESDAY WITH THE THREAT OF
SCATTERED SHOWERS PERSISTING THROUGH THE DAY. IN ADDITION...A
THERMAL TROF WILL CROSS INTO IOWA DURING THE DAY AND HAVE BEGUN
TRENDING TEMPERATURES DOWNWARD ON TUESDAY AND ESPECIALLY INTO
WEDNESDAY AS THE COLDER AIR ENTERS THE STATE.
A BRIEF RESPITE FROM PRECIPITATION CHANCES IS EXPECTED WEDNESDAY
NIGHT INTO FRIDAY AS WEAK SURFACE RIDGING SLIDES ACROSS THE STATE.
HOWEVER...BY LATE IN THE WORK WEEK...A LARGE WESTERN TROF IS
FORECAST TO DEVELOP BY BOTH THE GFS AND EURO. IOWA WILL BE LOCATED
UNDERNEATH THE UPPER RIDGE IN AN AREA OF LOW LEVEL MOISTURE
TRANSPORT AND WARM ADVECTION. SEVERAL SHORTWAVES ARE EXPECTED TO
EJECT OUT OF THE LARGE WESTERN TROF AND TOWARD THE MIDWEST
STARTING FRIDAY NIGHT AND CONTINUING INTO THE WEEKEND. IT APPEARS
THAT SEVERAL ROUNDS OF CONVECTION WILL OCCUR IN IOWA DURING THIS
TIME WITH THE POSSIBILITY OF LOCALIZED HEAVY RAINS AND SOME SEVERE
WEATHER. HOWEVER...DETAILS OF THE THREATS WILL HAVE TO BE HAMMERED
OUT AS THE TIMEFRAME APPROACHES.
&&
.AVIATION...20/18Z
ISSUED AT 1222 PM CDT MON MAY 20 2013
PRIMARY CONCERNS ARE WINDS AND TIMING OF CONVECTION THIS AFTERNOON
AND EVENING. PREVIOUS TIMING LOOKS GOOD WTIH SOME SCT ACTIVITY
DEVELOPING IN THE AFTERNOON/EVENING HOURS UNTIL INSTABILITY
LESSENS. AREA OF CLOUDS OVER NORTHERN IOWA MVFR AND WILL CONTINUE
TO HOLD ON AS AREA MOVES EAST NORTHEAST. SHOWERS SHOULD DEVELOP
NORTHWEST AS WELL. WINDS PICK UP AGAIN TUESDAY AFTER MIXING BEGINS
AROUND 14 TO 15Z.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...REV
SHORT TERM...BEERENDS
LONG TERM...COGIL
AVIATION...REV
000
FXUS63 KDVN 201630
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1130 AM CDT MON MAY 20 2013
.UPDATE...
ISSUED AT 1104 AM CDT MON MAY 20 2013
QUICK ASSESSMENT ON THIS MORNINGS UPPER AIR ANALYSIS AND WHAT IS
TAKING PACE CURRENTLY...SEEMS THERE MAY BE A DELAY TO LATER THIS
AFTERNOON AND EARLY EVENING. CURRENT TEMPS IN THE LOW TO MID 70S
WITH SFC DPTS MAINLY IN THE LOW 60S WILL STILL TAKE TIME TO
IMPROVE UPON...ESPECIALLY WITH BETTER SFC MOISTURE POOLED ALONG
OUTFLOW BOUNDARY ACRS CENTRAL MO ATTM. THE LOCAL AREA UNDER A H85
MB AND H7 MB LULL IN MOISTURE AS WELL. MID AND UPPER JET MAX/S
ACRS THE GRT BSN AND SHIFTING INTO THE SOUTHWESTERN PLAINS THIS
MORNING WILL NOT NOSE UP ACRS THE CWA UNTIL AFTER 20Z-21Z THIS
AFTERNOON. IF SFC DPTS ONLY RECOVER INTO THE MID 60S...THE 12Z NAM
AND GFS PROGGED CAPES OF 1500-2000 J/KG MAY BE TOO HIGH. ALSO HIGH
TEMPS MAY BE MORE IN THE WAY OF LOW TO MID 80S AS OPPOSED TO MID
TO UPPER 80S THIS AFTERNOON. SFC WINDS CURRENTLY SOUTH AND MAINLY
SOUTHWESTERLY...THUS WITHOUT AND LLVL BACKING TO THE SOUTHEAST THE
LOWER LEVEL HELICITIES AND SHEAR DON/T APPEAR AS IMPRESSIVE AS
WHAT MAY BE EARLIER THOUGHT. BUT THERE APPEARS TO BE DECENT DEEPER
LAYER SPEED SHEAR WITH UNIFORM VERTICAL PROFILES. LCL LEVELS MAY
NOT BE AS LOW AS WHAT THE SHORT RANGE MODELS DEPICT IN THE
SOUTHEAST THIRD/1500-2000 FT AGL/ THIS AFTERNOON AS WELL LIMITING
A POSSIBLE TORNADIC THREAT. THUS ALL IN ALL...LESS INSTABILITY
BUT STILL STRONG KINEMATICS/SHEAR SUGGEST A THREAT FOR LARGE HAIL
AND DAMAGING DOWNBURST WINDS WITH STILL THE POSSIBILITY OF
SUPERCELL TYPE DISCRETE STORMS THIS AFTERNOON...BUT MAY BE LESS
WIDESPREAD THEN YESTERDAY. THE SOUTHEAST THIRD OF THE CWA MOST AT
RISK OF SVR STORMS THIS AFTERNOON. STILL CAN/T RULE OUT ISOLATED
TORNADOES AND ANY WATCH THAT DOES COME OUT WILL PROBABLY STILL BE
A TOR WATCH FOR THE LOCAL AREA. SECOND ROUND OF STORMS ALONG THE
MAIN FRONT ITSELF...CURRENTLY ACRS FAR WESTERN IA...MAY SWEEP ACRS
THE AREA FROM THE WEST NOT UNTIL MID EVENING. WILL STILL HAVE TO
BE VERY MUCH ON GUARD AND WATCH TRENDS THROUGH THE AFTERNOON.
12
UPDATE ISSUED AT 624 AM CDT MON MAY 20 2013
THE NOCTURNAL MCS WILL CONTINUE TO SLOWLY DISSIPATE THROUGH MID
MORNING AND MOST OF THE AREA SHOULD SEE DRY CONDITIONS THROUGH MID
DAY. AFTER MID DAY NEW CONVECTION WILL RAPIDLY DEVELOP ONCE
CONVECTIVE TEMPERATURE IS ACHIEVED.
DATA INDICATES DISCRETE CELLS WILL INITIALLY DEVELOP THAT EVOLVE
INTO ONE OR MORE LINEAR MCS EVENTS BY EARLY EVENING AND WILL
CONTINUE INTO THE LATE EVENING.
THERE IS STILL A GOOD POTENTIAL FOR SEVERE STORMS THIS AFTERNOON
AND EVENING. THE MORNING UA FLIGHT THAT IS UNDERWAY SHOWS
CONSIDERABLE SPEED SHEAR UP THROUGH 2KFT AGL. THE KEY TO
EVERYTHING WILL BE HOW THE UPPER JET ROTATING UP FROM THE SOUTHERN
PLAINS WILL INTERACT WITH LOWER LEVEL FEATURES.
BASED ON THE PROGGED PLACEMENT OF THE JET STRUCTURE AND
INSTABILITY AXIS...SEVERE STORMS APPEAR TO BE PROBABLE DURING THE
AFTERNOON AND EVENING HOURS. IF SEVERE STORMS OCCUR...DAMAGING
WINDS AND LARGE HAIL ARE A GIVEN. BASED ON PROGGED SHEAR PROFILES
AND BUOYANCY WITH INPUT FROM THE IN PROGRESS 12Z UA FLIGHT...
TORNADOES ARE ALSO POSSIBLE. IF TORNADOES DEVELOP WITH THE
DISCRETE CELLS...SIGNIFICANT TORNADOES MAY BE POSSIBLE. ..08..
&&
.SYNOPSIS...
ISSUED AT 304 AM CDT MON MAY 20 2013
06Z SFC ANALYSIS HAS A SYNOPTIC LOW NEAR KMBG WITH THE STATIONARY
FRONT RUNNING EAST THROUGH WISCONSIN AND LOWER MICHIGAN. MESOSCALE
LOWS WERE NEAR KFSD...KBVN...AND KCSM. NUMEROUS OUTFLOW BOUNDARIES
RAN FROM ILLINOIS BACK THROUGH MISSOURI. DEW POINTS WERE IN THE 50S
AND 60S ACROSS THE MIDWEST.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 304 AM CDT MON MAY 20 2013
TODAY WILL BE QUITE INTERESTING. MESOSCALE PROCESSES WILL DRIVE THE
SENSIBLE WX AND CONCEPTUALLY...THERE IS A GOOD PROBABILITY OF SEEING
SEVERE STORMS THIS AFTERNOON AND EVENING.
MCS AND LIFT TOOLS SUGGEST THE BULK OF THE MCS MOVING ACROSS MISSOURI
WILL REMAIN SOUTH OF THE AREA. HOWEVER...VORT MAXES HELPING TO DRIVE
THIS MCS WILL PUSH DECAYING SHRA AND SOME TSRA INTO THE CWFA THROUGH
SUNRISE WITH ACTIVITY DISSIPATING DURING THE MORNING.
THERE SHOULD BE A FEW HOURS OF QUIET WX FROM MID TO LATE MORNING
UNTIL CONVECTIVE TEMPERATURE IS ACHIEVED. ONCE THIS OCCURS...NEW
CONVECTION WILL DEVELOP DURING THE AFTERNOON AND BUILD INTO ONE OR
MORE SEVERE MESOSCALE CONVECTIVE COMPLEXES BY EARLY EVENING.
THE OVERALL PLACEMENT OF THE JET STRUCTURE AND INSTABILITY AXIS
POINT TO SEVERE STORMS DEVELOPING DURING THE AFTERNOON. LARGE HAIL
AND DAMAGING WINDS ARE A GIVEN. THE SHEAR PROFILES AND BUOYANCY IS
ALSO FAVORABLE FOR TORNADOES...POSSIBLY SIGNIFICANT.
BY LATE EVENING AND OVERNIGHT...STORM ACTIVITY WILL BE ON THE
DECREASE AS THE ATMOSPHERE COOLS.
08
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 304 AM CDT MON MAY 20 2013
TURNING COOLER AND UNSETTLED WITH PROBABLY COOL RAINS AGAIN THIS NEXT
WEEKEND.
OVERVIEW...INITIALIZATION AND VERIFICATION ON LARGER SCALES...OR
SYNOPTIC SCALE ARE GOOD BUT ALL SOLUTIONS POOR TO VERY POOR ON
PRECIPITATION/MOISTURE/CLOUDS. AGAIN HEAVY USE OF CONCEPTUAL FORCING
TOOLS WHICH HAS AIDED PAST SEVERAL DAYS. THIS SUPPORTS MORE SHOWERS
AND STORMS TUESDAY TURNING COOLER WITH CLOUDS AND SHOWERS WEDNESDAY.
RISK OF SEVERE TUESDAY IS QUESTIONABLE BASED ON CONVECTION AND NEXT
WAVE INTERACTIONS LATER ON TUESDAY. PREFER A 60/40 MIX OF FORCING
OF HI-RES ECMWF AND NAM-WRF INTO DAY 4...THEN A 50/50 OF HI-RES
ECMWF AND GFS DAY 4 AND BEYOND.
TUESDAY...POOR CONFIDENCE IN FORECAST POPS AS NEXT 24 HOURS WILL
IMPACT EVOLUTION OF UPPER LOW AND PROGRESS OF COOL FRONT AND
ASSOCIATED AMOUNT OF CLEARING/CLOUDS. UPPER JET SUPPORTS LIGHTER AND
LOWER POPS WEST WITH RISK OF LINGERING WAVE OF SHOWERS AND STORMS
THAT SHOULD TEND TO STAY BELOW SEVERE LEVELS. HIGHS 75 TO 80 FROM
NW TO SE. MINS MID 50S NW TO THE LOWER 60S SE SECTIONS.
WEDNESDAY...CLOUDY AND COOLER WITH RAIN OR RAIN SHOWERS. HIGHS IN
THE NORTH MAY NEED LOWERING WITH LOW CLOUDS AND POSSIBLY EVEN
DRIZZLE WITH COOL NORTH WINDS ARRIVING FROM NORTH TO SOUTH DURING
THE DAY A BIT EARLIER IN THE FORECAST FOR LATER SHIFTS. WEDNESDAY
NIGHT...LOW CLOUDS AND POSSIBLY LIGHT RAIN AND PROBABLY AREAS OF
DRIZZLE WITH MINS IN THE 50S.
THURSDAY AND FRIDAY...BELOW NORMAL TEMPERATURES MOSTLY IN 65 TO
72 DEGREE RANGE. CLOUDS WILL CLEAR IN THE AFTERNOON FROM NORTH TO
SOUTH AS CANADIAN HIGH PRESSURE MOVES IN. THURSDAY NIGHT...CLEAR
AND COOL WITH MINS PROBABLY MANY LOCATIONS 3+ DEGREES TOO MILD WITH
LOWER TO MIDDLE 40S SUGGESTED OVER NORTH SECTIONS. FRIDAY...SUNNY
AND COOL WITH LIGHT NE WINDS.
SATURDAY AND SUNDAY...WESTERLY WINDS TO UPGLIDE OVER COOL AIRMASS
THAT PRIMES THE REGION FOR COOL HIGHS DUE TO GOOD EVAPORATIVE
COOLING AND LIKELY RAIN AND ISOLATED STORMS POSSIBLE IN SOUTH AND
WEST SECTIONS. CHANCE POPS FOR NOW WILL LIKELY BE RAISED WITH
TIMING ISSUES BETTER CLARIFIED. ANOTHER MODERATE TO LOCALLY LOWER
END HEAVY RAIN EVENT WITH MOST AREAS PICKING UP .5 TO 1+ INCHES.
NICHOLS
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 624 AM CDT MON MAY 20 2013
NOCTURNAL CONVECTION IS DISSIPATING ACRS IOWA/ILLINOIS AND SHOULD
BE GONE BY 15Z/20. MORNING UPPER AIR FLIGHT HAS 40 KTS JUST OFF
THE SURFACE SO LLWS WAS INCLUDED IN ALL TAFS UNTIL THE INVERSION
BREAKS AROUND 15Z/20. OTHERWISE VFR CONDITIONS WILL BE SEEN
THROUGH 18Z/20. AFT 18Z/20 NEW CONVECTION WILL DVLP RAPIDLY WITH
SEVERE STORMS POSSIBLE. PROBABILITY IS HIGH THAT MVFR/IFR
CONDITIONS WITH G40 KTS WILL BE SEEN IF A TSRA AFFECTS A TAF SITE.
CONVECTION WILL CONTINUE PAST 00Z/21 WITH INCREASING PROBABILITY
OF MVFR CONDITIONS. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...12
SYNOPSIS...08
SHORT TERM...08
LONG TERM...NICHOLS
AVIATION...08
000
FXUS63 KDVN 201148
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
648 AM CDT MON MAY 20 2013
.UPDATE...
ISSUED AT 624 AM CDT MON MAY 20 2013
THE NOCTURNAL MCS WILL CONTINUE TO SLOWLY DISSIPATE THROUGH MID
MORNING AND MOST OF THE AREA SHOULD SEE DRY CONDITIONS THROUGH MID
DAY. AFTER MID DAY NEW CONVECTION WILL RAPIDLY DEVELOP ONCE
CONVECTIVE TEMPERATURE IS ACHIEVED.
DATA INDICATES DISCRETE CELLS WILL INITIALLY DEVELOP THAT EVOLVE
INTO ONE OR MORE LINEAR MCS EVENTS BY EARLY EVENING AND WILL
CONTINUE INTO THE LATE EVENING.
THERE IS STILL A GOOD POTENTIAL FOR SEVERE STORMS THIS AFTERNOON
AND EVENING. THE MORNING UA FLIGHT THAT IS UNDERWAY SHOWS
CONSIDERABLE SPEED SHEAR UP THROUGH 2KFT AGL. THE KEY TO
EVERYTHING WILL BE HOW THE UPPER JET ROTATING UP FROM THE SOUTHERN
PLAINS WILL INTERACT WITH LOWER LEVEL FEATURES.
BASED ON THE PROGGED PLACEMENT OF THE JET STRUCTURE AND
INSTABILITY AXIS...SEVERE STORMS APPEAR TO BE PROBABLE DURING THE
AFTERNOON AND EVENING HOURS. IF SEVERE STORMS OCCUR...DAMAGING
WINDS AND LARGE HAIL ARE A GIVEN. BASED ON PROGGED SHEAR PROFILES
AND BUOYANCY WITH INPUT FROM THE IN PROGRESS 12Z UA FLIGHT...
TORNADOES ARE ALSO POSSIBLE. IF TORNADOES DEVELOP WITH THE
DISCRETE CELLS...SIGNIFICANT TORNADOES MAY BE POSSIBLE. ..08..
&&
.SYNOPSIS...
ISSUED AT 304 AM CDT MON MAY 20 2013
06Z SFC ANALYSIS HAS A SYNOPTIC LOW NEAR KMBG WITH THE STATIONARY
FRONT RUNNING EAST THROUGH WISCONSIN AND LOWER MICHIGAN. MESOSCALE
LOWS WERE NEAR KFSD...KBVN...AND KCSM. NUMEROUS OUTFLOW BOUNDARIES
RAN FROM ILLINOIS BACK THROUGH MISSOURI. DEW POINTS WERE IN THE 50S
AND 60S ACROSS THE MIDWEST.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 304 AM CDT MON MAY 20 2013
TODAY WILL BE QUITE INTERESTING. MESOSCALE PROCESSES WILL DRIVE THE
SENSIBLE WX AND CONCEPTUALLY...THERE IS A GOOD PROBABILITY OF SEEING
SEVERE STORMS THIS AFTERNOON AND EVENING.
MCS AND LIFT TOOLS SUGGEST THE BULK OF THE MCS MOVING ACROSS MISSOURI
WILL REMAIN SOUTH OF THE AREA. HOWEVER...VORT MAXES HELPING TO DRIVE
THIS MCS WILL PUSH DECAYING SHRA AND SOME TSRA INTO THE CWFA THROUGH
SUNRISE WITH ACTIVITY DISSIPATING DURING THE MORNING.
THERE SHOULD BE A FEW HOURS OF QUIET WX FROM MID TO LATE MORNING
UNTIL CONVECTIVE TEMPERATURE IS ACHIEVED. ONCE THIS OCCURS...NEW
CONVECTION WILL DEVELOP DURING THE AFTERNOON AND BUILD INTO ONE OR
MORE SEVERE MESOSCALE CONVECTIVE COMPLEXES BY EARLY EVENING.
THE OVERALL PLACEMENT OF THE JET STRUCTURE AND INSTABILITY AXIS
POINT TO SEVERE STORMS DEVELOPING DURING THE AFTERNOON. LARGE HAIL
AND DAMAGING WINDS ARE A GIVEN. THE SHEAR PROFILES AND BUOYANCY IS
ALSO FAVORABLE FOR TORNADOES...POSSIBLY SIGNIFICANT.
BY LATE EVENING AND OVERNIGHT...STORM ACTIVITY WILL BE ON THE
DECREASE AS THE ATMOSPHERE COOLS.
08
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 304 AM CDT MON MAY 20 2013
TURNING COOLER AND UNSETTLED WITH PROBABLY COOL RAINS AGAIN THIS NEXT
WEEKEND.
OVERVIEW...INITIALIZATION AND VERIFICATION ON LARGER SCALES...OR
SYNOPTIC SCALE ARE GOOD BUT ALL SOLUTIONS POOR TO VERY POOR ON
PRECIPITATION/MOISTURE/CLOUDS. AGAIN HEAVY USE OF CONCEPTUAL FORCING
TOOLS WHICH HAS AIDED PAST SEVERAL DAYS. THIS SUPPORTS MORE SHOWERS
AND STORMS TUESDAY TURNING COOLER WITH CLOUDS AND SHOWERS WEDNESDAY.
RISK OF SEVERE TUESDAY IS QUESTIONABLE BASED ON CONVECTION AND NEXT
WAVE INTERACTIONS LATER ON TUESDAY. PREFER A 60/40 MIX OF FORCING
OF HI-RES ECMWF AND NAM-WRF INTO DAY 4...THEN A 50/50 OF HI-RES
ECMWF AND GFS DAY 4 AND BEYOND.
TUESDAY...POOR CONFIDENCE IN FORECAST POPS AS NEXT 24 HOURS WILL
IMPACT EVOLUTION OF UPPER LOW AND PROGRESS OF COOL FRONT AND
ASSOCIATED AMOUNT OF CLEARING/CLOUDS. UPPER JET SUPPORTS LIGHTER AND
LOWER POPS WEST WITH RISK OF LINGERING WAVE OF SHOWERS AND STORMS
THAT SHOULD TEND TO STAY BELOW SEVERE LEVELS. HIGHS 75 TO 80 FROM
NW TO SE. MINS MID 50S NW TO THE LOWER 60S SE SECTIONS.
WEDNESDAY...CLOUDY AND COOLER WITH RAIN OR RAIN SHOWERS. HIGHS IN
THE NORTH MAY NEED LOWERING WITH LOW CLOUDS AND POSSIBLY EVEN
DRIZZLE WITH COOL NORTH WINDS ARRIVING FROM NORTH TO SOUTH DURING
THE DAY A BIT EARLIER IN THE FORECAST FOR LATER SHIFTS. WEDNESDAY
NIGHT...LOW CLOUDS AND POSSIBLY LIGHT RAIN AND PROBABLY AREAS OF
DRIZZLE WITH MINS IN THE 50S.
THURSDAY AND FRIDAY...BELOW NORMAL TEMPERATURES MOSTLY IN 65 TO
72 DEGREE RANGE. CLOUDS WILL CLEAR IN THE AFTERNOON FROM NORTH TO
SOUTH AS CANADIAN HIGH PRESSURE MOVES IN. THURSDAY NIGHT...CLEAR
AND COOL WITH MINS PROBABLY MANY LOCATIONS 3+ DEGREES TOO MILD WITH
LOWER TO MIDDLE 40S SUGGESTED OVER NORTH SECTIONS. FRIDAY...SUNNY
AND COOL WITH LIGHT NE WINDS.
SATURDAY AND SUNDAY...WESTERLY WINDS TO UPGLIDE OVER COOL AIRMASS
THAT PRIMES THE REGION FOR COOL HIGHS DUE TO GOOD EVAPORATIVE
COOLING AND LIKELY RAIN AND ISOLATED STORMS POSSIBLE IN SOUTH AND
WEST SECTIONS. CHANCE POPS FOR NOW WILL LIKELY BE RAISED WITH
TIMING ISSUES BETTER CLARIFIED. ANOTHER MODERATE TO LOCALLY LOWER
END HEAVY RAIN EVENT WITH MOST AREAS PICKING UP .5 TO 1+ INCHES.
NICHOLS
&&
.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 624 AM CDT MON MAY 20 2013
NOCTURNAL CONVECTION IS DISSIPATING ACRS IOWA/ILLINOIS AND SHOULD
BE GONE BY 15Z/20. MORNING UPPER AIR FLIGHT HAS 40 KTS JUST OFF
THE SURFACE SO LLWS WAS INCLUDED IN ALL TAFS UNTIL THE INVERSION
BREAKS AROUND 15Z/20. OTHERWISE VFR CONDITIONS WILL BE SEEN
THROUGH 18Z/20. AFT 18Z/20 NEW CONVECTION WILL DVLP RAPIDLY WITH
SEVERE STORMS POSSIBLE. PROBABILITY IS HIGH THAT MVFR/IFR
CONDITIONS WITH G40 KTS WILL BE SEEN IF A TSRA AFFECTS A TAF SITE.
CONVECTION WILL CONTINUE PAST 00Z/21 WITH INCREASING PROBABILITY
OF MVFR CONDITIONS. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
UPDATE...08
SYNOPSIS...08
SHORT TERM...08
LONG TERM...NICHOLS
AVIATION...08
000
FXUS63 KDMX 201135
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
635 AM CDT MON MAY 20 2013
.SHORT TERM.../TODAY /...
ISSUED AT 350 AM CDT MON MAY 20 2013
AREA OF SURFACE LOW PRESSURE OFF TO THE NORTHWEST ACROSS EASTERN
SD...WITH ASSOCIATED COLD FRONT STRETCHING SOUTHWARD ACROSS CENTRAL
NE INTO EXTREME NW KS. DRY SLOT CURRENTLY PUSHING THROUGH KS INTO
ERN NE...WILL CONTINUE TO PUSH ENE INTO IOWA THROUGH THE NEXT FEW
HOURS...WHICH SHOULD KEEP ANY PRECIP OFF TO THE SOUTHEAST THROUGH
SUNRISE POSSIBLY CLIPPING THE FAR SOUTHEASTERN CWA. OTHERWISE
ANOTHER VORT LOBE ROTATING AROUND THE UPPER LOW SITUATED OVER THE
WESTERN DAKOTAS WILL ROTATE THROUGH NORTHWEST IOWA THIS
MORNING...BRINGING THE POSSIBILITY OF SOME SHOWER/THUNDERSTORMS
TOWARD MID/LATE MORNING ACROSS THE FAR NORTHWESTERN CWA. REMAINDER
OF THE CWA SHOULD SEE MAINLY DRY CONDITIONS THROUGH MUCH OF THE
DAY...WITH SOUTHERLY FLOW AND MOISTURE CONTINUING TO PUSH BACK INTO
THE EASTERN CWA. SOUNDINGS INDICATING EASTERN CWA TO BECOME
DESTABILIZE AROUND 21-00Z WITH CAPE VALUES IN THE 1500 TO 2500 J/KG
AND SUFFICIENT DEEP LAYER SHEAR. THEREFORE HAVE POPS RETURNING THIS
AFTERNOON ACROSS THE REMAINDER OF THE CWA...WITH GREATEST CHANCE FOR
SEVERE WEATHER ALSO WITH THIS MID/LATE AFTERNOON ACTIVITY ACROSS THE
EAST/SOUTHEASTERN CWA.
TEMPERATURES EXPECTED TO BE A BIT COOLER TODAY WITH SLIGHTLY COOLER
AIRMASS ALOFT...WITH COOLEST TEMPS ACROSS THE NORTHWEST WHERE
CLOUDS/PRECIP CHANCES EXPECTED THROUGHOUT THE DAY. OVERALL HIGHS IN
THE 70S NORTH TO LOW/MID 80S SOUTH. SOUTHERLY WINDS TO BE BREEZY
AGAIN TODAY AS STRONGER WINDS ALOFT MIX TO THE SURFACE.
.LONG TERM.../TONIGHT THROUGH SATURDAY/...
ISSUED AT 350 AM CDT MON MAY 20 2013
CONVECTION WILL BE ONGOING THIS EVENING BUT WILL BE DEPARTING
QUICKLY TO THE NORTHEAST AS THE SHORTWAVE PASSES THROUGH THE
STATE. ANY SEVERE CONVECTION WILL LIKELY BE EARLY THIS EVENING IN
THE SOUTHEAST PRIOR TO MORE STABLE AIRMASS AND PRECIPITATION
DEPARTURE BY LATE EVENING. AFTER MIDNIGHT TONIGHT...MUCH OF THE
AREA SHOULD SEE LITTLE IF ANY RAINFALL AS DRIER AIR ENTERS THE
STATE AND SUBSIDENCE INCREASES...ESPECIALLY IN THE SOUTH. MUCH OF
TUESDAY ALSO APPEARS DRY ALTHOUGH SOME AFTERNOON REDEVELOPMENT
REMAIN POSSIBLE AS UPPER LOW SLIPS TOWARD THE STATE. THIS LOW WILL
SLIDE ACROSS NORTHERN IOWA ON WEDNESDAY WITH THE THREAT OF
SCATTERED SHOWERS PERSISTING THROUGH THE DAY. IN ADDITION...A
THERMAL TROF WILL CROSS INTO IOWA DURING THE DAY AND HAVE BEGUN
TRENDING TEMPERATURES DOWNWARD ON TUESDAY AND ESPECIALLY INTO
WEDNESDAY AS THE COLDER AIR ENTERS THE STATE.
A BRIEF RESPITE FROM PRECIPITATION CHANCES IS EXPECTED WEDNESDAY
NIGHT INTO FRIDAY AS WEAK SURFACE RIDGING SLIDES ACROSS THE STATE.
HOWEVER...BY LATE IN THE WORK WEEK...A LARGE WESTERN TROF IS
FORECAST TO DEVELOP BY BOTH THE GFS AND EURO. IOWA WILL BE LOCATED
UNDERNEATH THE UPPER RIDGE IN AN AREA OF LOW LEVEL MOISTURE
TRANSPORT AND WARM ADVECTION. SEVERAL SHORTWAVES ARE EXPECTED TO
EJECT OUT OF THE LARGE WESTERN TROF AND TOWARD THE MIDWEST
STARTING FRIDAY NIGHT AND CONTINUING INTO THE WEEKEND. IT APPEARS
THAT SEVERAL ROUNDS OF CONVECTION WILL OCCUR IN IOWA DURING THIS
TIME WITH THE POSSIBILITY OF LOCALIZED HEAVY RAINS AND SOME SEVERE
WEATHER. HOWEVER...DETAILS OF THE THREATS WILL HAVE TO BE HAMMERED
OUT AS THE TIMEFRAME APPROACHES.
&&
.AVIATION...20/12Z
ISSUED AT 630 AM CDT MON MAY 20 2013
IFR/MVFR CIGS EXPECTED TO LIFT TO VFR THROUGH THE MORNING ACROSS
THE NORTHERN TAF SITES...WITH VFR CONDITIONS EXPECTED ACROSS THE
SOUTH. SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED TO
DEVELOP/SPREAD ACROSS NORTHWESTERN INTO NORTH CENTRAL PORTIONS OF
THE STATE THIS MORNING. FOR NOW EXPECT ACTIVITY TO STAY NORTHWEST
OF KFOD...WITH THE AFTERNOON ACTIVITY EAST/SOUTHEAST OF KFOD.
THEREFORE KEPT KFOD DRY FOR THE ENTIRE FORECAST PERIOD. COULD
OTHERWISE BETTER CHANCES FOR THUNDERSTORMS AT THE OTHER 4 TAF
SITES THIS AFTERNOON INTO THIS EVENING. TRIED TO HIGHLIGHT THE
BEST TIMES FOR THUNDER AT EACH SITE. BREEZY SOUTH TO SOUTHWESTERLY
WINDS EXPECTED THROUGH THE PERIOD.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...BEERENDS
LONG TERM...COGIL
AVIATION...BEERENDS
000
FXUS63 KDMX 200851
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
351 AM CDT MON MAY 20 2013
.SHORT TERM.../TODAY /...
ISSUED AT 350 AM CDT MON MAY 20 2013
AREA OF SURFACE LOW PRESSURE OFF TO THE NORTHWEST ACROSS EASTERN
SD...WITH ASSOCIATED COLD FRONT STRETCHING SOUTHWARD ACROSS CENTRAL
NE INTO EXTREME NW KS. DRY SLOT CURRENTLY PUSHING THROUGH KS INTO
ERN NE...WILL CONTINUE TO PUSH ENE INTO IOWA THROUGH THE NEXT FEW
HOURS...WHICH SHOULD KEEP ANY PRECIP OFF TO THE SOUTHEAST THROUGH
SUNRISE POSSIBLY CLIPPING THE FAR SOUTHEASTERN CWA. OTHERWISE
ANOTHER VORT LOBE ROTATING AROUND THE UPPER LOW SITUATED OVER THE
WESTERN DAKOTAS WILL ROTATE THROUGH NORTHWEST IOWA THIS
MORNING...BRINGING THE POSSIBILITY OF SOME SHOWER/THUNDERSTORMS
TOWARD MID/LATE MORNING ACROSS THE FAR NORTHWESTERN CWA. REMAINDER
OF THE CWA SHOULD SEE MAINLY DRY CONDITIONS THROUGH MUCH OF THE
DAY...WITH SOUTHERLY FLOW AND MOISTURE CONTINUING TO PUSH BACK INTO
THE EASTERN CWA. SOUNDINGS INDICATING EASTERN CWA TO BECOME
DESTABILIZE AROUND 21-00Z WITH CAPE VALUES IN THE 1500 TO 2500 J/KG
AND SUFFICIENT DEEP LAYER SHEAR. THEREFORE HAVE POPS RETURNING THIS
AFTERNOON ACROSS THE REMAINDER OF THE CWA...WITH GREATEST CHANCE FOR
SEVERE WEATHER ALSO WITH THIS MID/LATE AFTERNOON ACTIVITY ACROSS THE
EAST/SOUTHEASTERN CWA.
TEMPERATURES EXPECTED TO BE A BIT COOLER TODAY WITH SLIGHTLY COOLER
AIRMASS ALOFT...WITH COOLEST TEMPS ACROSS THE NORTHWEST WHERE
CLOUDS/PRECIP CHANCES EXPECTED THROUGHOUT THE DAY. OVERALL HIGHS IN
THE 70S NORTH TO LOW/MID 80S SOUTH. SOUTHERLY WINDS TO BE BREEZY
AGAIN TODAY AS STRONGER WINDS ALOFT MIX TO THE SURFACE.
.LONG TERM.../TONIGHT THROUGH SATURDAY/...
ISSUED AT 350 AM CDT MON MAY 20 2013
CONVECTION WILL BE ONGOING THIS EVENING BUT WILL BE DEPARTING
QUICKLY TO THE NORTHEAST AS THE SHORTWAVE PASSES THROUGH THE
STATE. ANY SEVERE CONVECTION WILL LIKELY BE EARLY THIS EVENING IN
THE SOUTHEAST PRIOR TO MORE STABLE AIRMASS AND PRECIPITATION
DEPARTURE BY LATE EVENING. AFTER MIDNIGHT TONIGHT...MUCH OF THE
AREA SHOULD SEE LITTLE IF ANY RAINFALL AS DRIER AIR ENTERS THE
STATE AND SUBSIDENCE INCREASES...ESPECIALLY IN THE SOUTH. MUCH OF
TUESDAY ALSO APPEARS DRY ALTHOUGH SOME AFTERNOON REDEVELOPMENT
REMAIN POSSIBLE AS UPPER LOW SLIPS TOWARD THE STATE. THIS LOW WILL
SLIDE ACROSS NORTHERN IOWA ON WEDNESDAY WITH THE THREAT OF
SCATTERED SHOWERS PERSISTING THROUGH THE DAY. IN ADDITION...A
THERMAL TROF WILL CROSS INTO IOWA DURING THE DAY AND HAVE BEGUN
TRENDING TEMPERATURES DOWNWARD ON TUESDAY AND ESPECIALLY INTO
WEDNESDAY AS THE COLDER AIR ENTERS THE STATE.
A BRIEF RESPITE FROM PRECIPITATION CHANCES IS EXPECTED WEDNESDAY
NIGHT INTO FRIDAY AS WEAK SURFACE RIDGING SLIDES ACROSS THE STATE.
HOWEVER...BY LATE IN THE WORK WEEK...A LARGE WESTERN TROF IS
FORECAST TO DEVELOP BY BOTH THE GFS AND EURO. IOWA WILL BE LOCATED
UNDERNEATH THE UPPER RIDGE IN AN AREA OF LOW LEVEL MOISTURE
TRANSPORT AND WARM ADVECTION. SEVERAL SHORTWAVES ARE EXPECTED TO
EJECT OUT OF THE LARGE WESTERN TROF AND TOWARD THE MIDWEST
STARTING FRIDAY NIGHT AND CONTINUING INTO THE WEEKEND. IT APPEARS
THAT SEVERAL ROUNDS OF CONVECTION WILL OCCUR IN IOWA DURING THIS
TIME WITH THE POSSIBILITY OF LOCALIZED HEAVY RAINS AND SOME SEVERE
WEATHER. HOWEVER...DETAILS OF THE THREATS WILL HAVE TO BE HAMMERED
OUT AS THE TIMEFRAME APPROACHES.
&&
.AVIATION...20/06Z
ISSUED AT 1146 PM CDT SUN MAY 19 2013
ONLY ISOLD SHRA OR TSRA OVERNIGHT. DURING THE DAY MONDAY SFC WIND
WILL INCREASE TO 20G30KT AS ANOTHER UPPER LEVEL FEATURE APPROACHES
IOWA. ADDITIONAL STORMS TO FIRE AFT 21Z MAINLY EAST OF I-35 BUT IF
THEY GET GOING BEFORE 21Z COULD BE A LITTLE FURTHER WEST. LARGE
HAIL AND DAMAGING WIND AGAIN POSSIBLE AFT 21/00Z THROUGH ROUGHLY
04-06Z.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...BEERENDS
LONG TERM...COGIL
AVIATION...FAB
000
FXUS63 KDVN 200837
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
337 AM CDT MON MAY 20 2013
.SYNOPSIS...
ISSUED AT 304 AM CDT MON MAY 20 2013
06Z SFC ANALYSIS HAS A SYNOPTIC LOW NEAR KMBG WITH THE STATIONARY
FRONT RUNNING EAST THROUGH WISCONSIN AND LOWER MICHIGAN. MESOSCALE
LOWS WERE NEAR KFSD...KBVN...AND KCSM. NUMEROUS OUTFLOW BOUNDARIES
RAN FROM ILLINOIS BACK THROUGH MISSOURI. DEW POINTS WERE IN THE 50S
AND 60S ACROSS THE MIDWEST.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 304 AM CDT MON MAY 20 2013
TODAY WILL BE QUITE INTERESTING. MESOSCALE PROCESSES WILL DRIVE THE
SENSIBLE WX AND CONCEPTUALLY...THERE IS A GOOD PROBABILITY OF SEEING
SEVERE STORMS THIS AFTERNOON AND EVENING.
MCS AND LIFT TOOLS SUGGEST THE BULK OF THE MCS MOVING ACROSS MISSOURI
WILL REMAIN SOUTH OF THE AREA. HOWEVER...VORT MAXES HELPING TO DRIVE
THIS MCS WILL PUSH DECAYING SHRA AND SOME TSRA INTO THE CWFA THROUGH
SUNRISE WITH ACTIVITY DISSIPATING DURING THE MORNING.
THERE SHOULD BE A FEW HOURS OF QUIET WX FROM MID TO LATE MORNING
UNTIL CONVECTIVE TEMPERATURE IS ACHIEVED. ONCE THIS OCCURS...NEW
CONVECTION WILL DEVELOP DURING THE AFTERNOON AND BUILD INTO ONE OR
MORE SEVERE MESOSCALE CONVECTIVE COMPLEXES BY EARLY EVENING.
THE OVERALL PLACEMENT OF THE JET STRUCTURE AND INSTABILITY AXIS
POINT TO SEVERE STORMS DEVELOPING DURING THE AFTERNOON. LARGE HAIL
AND DAMAGING WINDS ARE A GIVEN. THE SHEAR PROFILES AND BUOYANCY IS
ALSO FAVORABLE FOR TORNADOES...POSSIBLY SIGNIFICANT.
BY LATE EVENING AND OVERNIGHT...STORM ACTIVITY WILL BE ON THE
DECREASE AS THE ATMOSPHERE COOLS.
08
.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 304 AM CDT MON MAY 20 2013
TURNING COOLER AND UNSETTLED WITH PROBABLY COOL RAINS AGAIN THIS NEXT
WEEKEND.
OVERVIEW...INITIALIZATION AND VERIFICATION ON LARGER SCALES...OR
SYNOPTIC SCALE ARE GOOD BUT ALL SOLUTIONS POOR TO VERY POOR ON
PRECIPITATION/MOISTURE/CLOUDS. AGAIN HEAVY USE OF CONCEPTUAL FORCING
TOOLS WHICH HAS AIDED PAST SEVERAL DAYS. THIS SUPPORTS MORE SHOWERS
AND STORMS TUESDAY TURNING COOLER WITH CLOUDS AND SHOWERS WEDNESDAY.
RISK OF SEVERE TUESDAY IS QUESTIONABLE BASED ON CONVECTION AND NEXT
WAVE INTERACTIONS LATER ON TUESDAY. PREFER A 60/40 MIX OF FORCING
OF HI-RES ECMWF AND NAM-WRF INTO DAY 4...THEN A 50/50 OF HI-RES
ECMWF AND GFS DAY 4 AND BEYOND.
TUESDAY...POOR CONFIDENCE IN FORECAST POPS AS NEXT 24 HOURS WILL
IMPACT EVOLUTION OF UPPER LOW AND PROGRESS OF COOL FRONT AND
ASSOCIATED AMOUNT OF CLEARING/CLOUDS. UPPER JET SUPPORTS LIGHTER AND
LOWER POPS WEST WITH RISK OF LINGERING WAVE OF SHOWERS AND STORMS
THAT SHOULD TEND TO STAY BELOW SEVERE LEVELS. HIGHS 75 TO 80 FROM
NW TO SE. MINS MID 50S NW TO THE LOWER 60S SE SECTIONS.
WEDNESDAY...CLOUDY AND COOLER WITH RAIN OR RAIN SHOWERS. HIGHS IN
THE NORTH MAY NEED LOWERING WITH LOW CLOUDS AND POSSIBLY EVEN
DRIZZLE WITH COOL NORTH WINDS ARRIVING FROM NORTH TO SOUTH DURING
THE DAY A BIT EARLIER IN THE FORECAST FOR LATER SHIFTS. WEDNESDAY
NIGHT...LOW CLOUDS AND POSSIBLY LIGHT RAIN AND PROBABLY AREAS OF
DRIZZLE WITH MINS IN THE 50S.
THURSDAY AND FRIDAY...BELOW NORMAL TEMPERATURES MOSTLY IN 65 TO
72 DEGREE RANGE. CLOUDS WILL CLEAR IN THE AFTERNOON FROM NORTH TO
SOUTH AS CANADIAN HIGH PRESSURE MOVES IN. THURSDAY NIGHT...CLEAR
AND COOL WITH MINS PROBABLY MANY LOCATIONS 3+ DEGREES TOO MILD WITH
LOWER TO MIDDLE 40S SUGGESTED OVER NORTH SECTIONS. FRIDAY...SUNNY
AND COOL WITH LIGHT NE WINDS.
SATURDAY AND SUNDAY...WESTERLY WINDS TO UPGLIDE OVER COOL AIRMASS
THAT PRIMES THE REGION FOR COOL HIGHS DUE TO GOOD EVAPORATIVE
COOLING AND LIKELY RAIN AND ISOLATED STORMS POSSIBLE IN SOUTH AND
WEST SECTIONS. CHANCE POPS FOR NOW WILL LIKELY BE RAISED WITH
TIMING ISSUES BETTER CLARIFIED. ANOTHER MODERATE TO LOCALLY LOWER
END HEAVY RAIN EVENT WITH MOST AREAS PICKING UP .5 TO 1+ INCHES.
NICHOLS
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 304 AM CDT MON MAY 20 2013
THE STORM COMPLEX ACROSS MISSOURI WILL MOVE INTO SOUTHERN ILLINOIS
THROUGH SUNRISE. A DISTURBANCE ALOFT WILL PUSH SHOWERS AND A FEW
TSRA INTO EASTERN IOWA AND NORTHERN ILLINOIS THAT WILL SLOWLY
DISSIPATE THROUGH 12Z/20. MAINLY VFR CONDITIONS ARE EXPECTED BUT
BRIEF MVFR CONDITIONS ARE POSSIBLE WITH ANY SHRA/TSRA. AFT 12Z/20
VFR CONDITIONS ARE EXPECTED WITH NEW STORMS DVLPG AFT 18Z/20. STORMS
THAT DVLP AFT 18Z/20 WILL BE STRONG TO SEVERE WITH THE POTENTIAL FOR
IFR CONDITIONS.
08
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...08
SHORT TERM...08
LONG TERM...NICHOLS
AVIATION...08
000
FXUS63 KDVN 200531
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1231 AM CDT MON MAY 20 2013
.SYNOPSIS...
ISSUED AT 322 PM CDT SUN MAY 19 2013
CONDITIONS COMING TOGETHER THIS AFTERNOON AND EVENING FOR A
SEVERE WEATHER OUTBREAK AND TORNADO WATCHES ARE IN PLACE FOR LATE
THIS AFTERNOON AND EVENING FOR ALL BUT THE EASTERN THIRD OF THE
FORECAST AREA. THESE INGREDIENTS INCLUDE TEMPERATURES IN THE
80S...DEWPOINTS IN THE UPPER 60S TO LOWER 70S. MID LEVEL SPEED MAX
ROTATING AROUND THE BASE OF A DEVELOPING UPPER LOW OVER THE PLAINS
WILL INCREASE DEEP SHEAR AS IT APPROACHES THIS EVENING. NUMEROUS
MESOSCALE OUTFLOW BOUNDARIES AND AN AXIS OF PRESSURE FALLS ALSO
SIGNAL IMPENDING DEVELOPMENT OF STORMS.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 322 PM CDT SUN MAY 19 2013
A SOMEWHAT SHORTENED DISCUSSION THIS AFTERNOON DUE TO DEVELOPING
SIGNIFICANT WEATHER. FOCUS FOR BOTH SHORT TERM INTO THE EARLY
PERIODS OF THE LONG TERM REMAINS ON THUNDERSTORMS AND POTENTIAL FOR
SEVERE WEATHER.
THIS AFTERNOON INTO THIS EVENING...THE INITIAL DEVELOPMENT WILL
LIKELY BE ALONG A NORTH-SOUTH BOUNDARY BISECTING IA JUST WEST OF
THE FORECAST AREA. AXIS OF PRESSURE FALLS FROM NE MO...ADJACENT W
CENTRAL IL NORTHWARD INTO EASTERN IA SIGNALS AN AREA OF
DESTABILIZATION IN THE CLEARING AND WAKE OF STORMS MOVING INTO SW
WI. SEVERE STORMS INITIALLY OVER THIS AREA THIS EVENING WILL
LIKELY TRANSITION INTO A LARGER MCS...EXITING TO THE EAST-
NORTHEAST...FOLLOWING SYNOPTIC FORCING OF A SHORTWAVE LIFTING OUT
OF THE CENTRAL PLAINS.
AS MENTIONED IN PREVIOUS DISCUSSIONS...INGREDIENTS REMAIN IN PLACE
FOR SEVERE WEATHER FOR MONDAY WITH THE ADDITION OF STRONGER DEEP
LAYER SHEAR TO SUPPORT SUPERCELLS AND TORNADOES. THE FOCUS AND
TRIGGER FOR STORMS WILL AGAIN BE CENTERED ON A MID LEVEL WAVE
LIFTING OUT OF THE SOUTHWEST AND ITS INTERACTION WITH MESOSCALE
BOUNDARIES. TEMPERATURES SHOULD AGAIN REACH INTO THE 80S WITH
DEWPOINTS IN THE UPPER 60S TO LOWER 70S. SPC CURRENTLY HAS A SLIGHT
RISK IN PLACE FOR DAY 2.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 322 PM CDT SUN MAY 19 2013
ALTHOUGH NOT AS IDEAL AS TODAY OR MONDAY...SEVERE WEATHER WILL AGAIN
BE POSSIBLE TUESDAY AND SPC HAS A SLIGHT RISK OVER THE AREA FOR DAY
3. OTHERWISE...THE OVERALL TREND IN THE EXTENDED FORECAST IS TOWARD
MORE STABLE...NOT AS WARM...AND DRIER WEATHER LATE WEEK AS THE
PLAINS LOW WEAKENS AND MOVES OUT...REPLACED BY HIGH PRESSURE. MODELS
CONTINUE TO DIVERGE SOME WITH HOW QUICKLY THE RIDGE MOVES OUT BY
NEXT WEEKEND AND THE TIMING OF A WARM FRONT THAT MAY BRING RAIN
CHANCES BY LATE SATURDAY AND ESPECIALLY SATURDAY NIGHT AND MONDAY.
&&
.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 1226 AM CDT MON MAY 20 2013
FIRST LINE OF TSRA IS MOVING EAST OF THE MISSISSIPPI AND INTO
WISCONSIN. THE NEXT LINE IS MOVING NORTHEAST FROM MISSOURI AND
SHOULD AFFECT PARTS OF IOWA/ILLINOIS THROUGH 12Z/20. MVFR/IFR
CONDITIONS WILL BE SEEN WITH TSRA WITH VFR CONDITIONS OUTSIDE OF
TSRA. VFR CONDITIONS ARE EXPECTED AFT 12Z/20 WITH NEW CONVECTION
DVLPG AFT 18Z/20. THE POTENTIAL EXISTS FOR MVFR/IFR CONDITIONS
WITH TSRA AFT 18Z/20. ..08..
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AVIATION...08
000
FXUS63 KDMX 200445
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1146 PM CDT SUN MAY 19 2013
.SHORT TERM.../TONIGHT /...
ISSUED AT 330 PM CDT SUN MAY 19 2013
MAIN CONCERNS ARE SEVERE WEATHER THIS PERIOD. CURRENT WATCHES
ACROSS THE AREA FOR THE POTENTIAL OF TORNADOES THIS EVENING.
THOUGH INSTABILITY HAS WANED ACROSS CENTRAL AND WESTERN SECTIONS
OF IOWA WITH SHORT WAVE APPROACHING FROM THE SOUTH INSTABILITY
WILL ONCE AGAIN INCREASE OVER THE REGION. MODELS HAVE CONTINUED TO
ADVERTISE INCREASING WIND FIELDS ALOFT WITH APPROACHING WAVE WHICH
SHOULD SUPPORT SUPERCELLS WITH TORNADO POTENTIAL AS WELL. LOWS
OVERNIGHT WILL DROP INTO THE 60S WITH WINDS BECOMING MORE SW AS
DRY SLOT WORKS ITS WAY INTO THE AREA AFT 06Z. EXPECTING MOST OF
THE ACTIVITY TO REACH WEST CENTRAL IOWA BY 22Z AND NEARING CENTRAL
SECTIONS BY 00-01Z WITH EASTERN COUNTIES SEEING STORMS THROUGH
03Z.
.LONG TERM.../MONDAY THROUGH SUNDAY/...
ISSUED AT 330 PM CDT SUN MAY 19 2013
FORECAST CONCERN DEALS WITH CUTOFF LOW LINGERING OVER THE MIDWEST
THROUGH THE MIDDLE OF THE WEEK AND TIMING OF PRECIP CHANCES
ASSOCIATED WITH THIS SYSTEM. MODELS ARE IN GOOD AGREEMENT THROUGH
MID WEEK AND LEANED TOWARD A NAM/ECMWF BLEND.
.MONDAY THROUGH WEDNESDAY...UPPER LOW STALLS OR SLIGHTLY
RETROGRADES INTO EASTERN SOUTH DAKOTA TOMORROW AND LOOKS TO PLACE
MUCH OF THE FORECAST AREA IN THE DRY SLOT. CUT BACK ON POPS DURING
THE DAY OVER CENTRAL AND SOUTHERN PORTIONS OF THE FORECAST AREA
WHERE BEST FORCING PUSHES INTO NORTHERN IOWA AND INTO MINNESOTA.
LATEST 4.0KM WRF PUSHES CONVECTION INTO FAR NORTHERN IOWA AND
INTO MINNESOTA BY 12Z MONDAY AND KEEPS THE REST OF THE FORECAST
AREA MAINLY DRY UNTIL LATE IN THE DAY. SEVERE POTENTIAL EXIST
ACROSS EASTERN SECTIONS OF THE FORECAST AREA BY THE LATE
AFTERNOON AS THE PEAK HEATING AIDS IN DESTABILIZATION. MAIN THREAT
LOOKS TO BE HAIL AND WINDS WITH THE DECENT CAPE PRESENT AND DEEP
LAYER SHEAR. ANOTHER SHORTWAVE ROUNDS THE UPPER LOW MONDAY NIGHT
AND LIKELY WILL BE THE TRIGGER FOR STORMS ACROSS EASTERN AND
NORTHERN IOWA. HAVE HIGHEST POPS OVER EASTERN PORTIONS OF THE
FORECAST AREA THROUGH 06Z TUESDAY. DRY SLOT MOVES BACK INTO IOWA
PAST 12Z TUESDAY AND HAD TO CUT BACK ON POPS OVER CENTRAL TO
SOUTHERN IOWA DURING THE DAY TUESDAY. THE UPPER LOW FINALLY PUSHES
EASTWARD INTO NORTHERN IOWA BY WEDNESDAY MORNING AND BRINGS SOME
LIGHT STRATI-FORM RAIN DURING THE DAY WEDNESDAY.
.THURSDAY THROUGH SATURDAY...COLDER TEMPERATURES FILTER INTO THE
REGION DURING THIS TIME FRAME AS SURFACE HIGH BUILDS ACROSS THE
STATE. GENERALLY DRY CONDITIONS ANTICIPATED UNTIL SOME WEAK
THETA-E ADVECTION DEVELOPS LATE FRIDAY NIGHT INTO SATURDAY ON
THE BACKSIDE OF THE SURFACE HIGH.
&&
.AVIATION...20/06Z
ISSUED AT 1146 PM CDT SUN MAY 19 2013
ONLY ISOLD SHRA OR TSRA OVERNIGHT. DURING THE DAY MONDAY SFC WIND
WILL INCREASE TO 20G30KT AS ANOTHER UPPER LEVEL FEATURE APPROACHES
IOWA. ADDITIONAL STORMS TO FIRE AFT 21Z MAINLY EAST OF I-35 BUT IF
THEY GET GOING BEFORE 21Z COULD BE A LITTLE FURTHER WEST. LARGE
HAIL AND DAMAGING WIND AGAIN POSSIBLE AFT 21/00Z THROUGH ROUGHLY
04-06Z.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...REV
LONG TERM...PODRAZIK
AVIATION...FAB
000
FXUS63 KDMX 200027 RRA
AFDDMX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
712 PM CDT SUN MAY 19 2013
.SHORT TERM.../TONIGHT /...
ISSUED AT 330 PM CDT SUN MAY 19 2013
MAIN CONCERNS ARE SEVERE WEATHER THIS PERIOD. CURRENT WATCHES
ACROSS THE AREA FOR THE POTENTIAL OF TORNADOES THIS EVENING.
THOUGH INSTABILITY HAS WANED ACROSS CENTRAL AND WESTERN SECTIONS
OF IOWA WITH SHORT WAVE APPROACHING FROM THE SOUTH INSTABILITY
WILL ONCE AGAIN INCREASE OVER THE REGION. MODELS HAVE CONTINUED TO
ADVERTISE INCREASING WIND FIELDS ALOFT WITH APPROACHING WAVE WHICH
SHOULD SUPPORT SUPERCELLS WITH TORNADO POTENTIAL AS WELL. LOWS
OVERNIGHT WILL DROP INTO THE 60S WITH WINDS BECOMING MORE SW AS
DRY SLOT WORKS ITS WAY INTO THE AREA AFT 06Z. EXPECTING MOST OF
THE ACTIVITY TO REACH WEST CENTRAL IOWA BY 22Z AND NEARING CENTRAL
SECTIONS BY 00-01Z WITH EASTERN COUNTIES SEEING STORMS THROUGH
03Z.
.LONG TERM.../MONDAY THROUGH SUNDAY/...
ISSUED AT 330 PM CDT SUN MAY 19 2013
FORECAST CONCERN DEALS WITH CUTOFF LOW LINGERING OVER THE MIDWEST
THROUGH THE MIDDLE OF THE WEEK AND TIMING OF PRECIP CHANCES
ASSOCIATED WITH THIS SYSTEM. MODELS ARE IN GOOD AGREEMENT THROUGH
MID WEEK AND LEANED TOWARD A NAM/ECMWF BLEND.
.MONDAY THROUGH WEDNESDAY...UPPER LOW STALLS OR SLIGHTLY
RETROGRADES INTO EASTERN SOUTH DAKOTA TOMORROW AND LOOKS TO PLACE
MUCH OF THE FORECAST AREA IN THE DRY SLOT. CUT BACK ON POPS DURING
THE DAY OVER CENTRAL AND SOUTHERN PORTIONS OF THE FORECAST AREA
WHERE BEST FORCING PUSHES INTO NORTHERN IOWA AND INTO MINNESOTA.
LATEST 4.0KM WRF PUSHES CONVECTION INTO FAR NORTHERN IOWA AND
INTO MINNESOTA BY 12Z MONDAY AND KEEPS THE REST OF THE FORECAST
AREA MAINLY DRY UNTIL LATE IN THE DAY. SEVERE POTENTIAL EXIST
ACROSS EASTERN SECTIONS OF THE FORECAST AREA BY THE LATE
AFTERNOON AS THE PEAK HEATING AIDS IN DESTABILIZATION. MAIN THREAT
LOOKS TO BE HAIL AND WINDS WITH THE DECENT CAPE PRESENT AND DEEP
LAYER SHEAR. ANOTHER SHORTWAVE ROUNDS THE UPPER LOW MONDAY NIGHT
AND LIKELY WILL BE THE TRIGGER FOR STORMS ACROSS EASTERN AND
NORTHERN IOWA. HAVE HIGHEST POPS OVER EASTERN PORTIONS OF THE
FORECAST AREA THROUGH 06Z TUESDAY. DRY SLOT MOVES BACK INTO IOWA
PAST 12Z TUESDAY AND HAD TO CUT BACK ON POPS OVER CENTRAL TO
SOUTHERN IOWA DURING THE DAY TUESDAY. THE UPPER LOW FINALLY PUSHES
EASTWARD INTO NORTHERN IOWA BY WEDNESDAY MORNING AND BRINGS SOME
LIGHT STRATI-FORM RAIN DURING THE DAY WEDNESDAY.
.THURSDAY THROUGH SATURDAY...COLDER TEMPERATURES FILTER INTO THE
REGION DURING THIS TIME FRAME AS SURFACE HIGH BUILDS ACROSS THE
STATE. GENERALLY DRY CONDITIONS ANTICIPATED UNTIL SOME WEAK
THETA-E ADVECTION DEVELOPS LATE FRIDAY NIGHT INTO SATURDAY ON
THE BACKSIDE OF THE SURFACE HIGH.
&&
.AVIATION...20/00Z
ISSUED AT 712 PM CDT SUN MAY 19 2013
LINE OF SEVERE STORMS FROM MCW TO KAMW TO N OF NWS OFFICE WILL MOVE
ACROSS THE TAF LOCATIONS THROUGH 10 PM. WND G55KTS POSSIBLE ALONG
WITH LARGE HAIL. ADDITIONAL STORMS OVER NEB WILL MOVE INTO WESTERN
IOWA OVERNIGHT BUT AIRMASS WILL NOT BE AS CONDUCIVE TO SEVERE
STORMS. SHOULD BE A BREAK AFT 12Z THROUGH 21Z BEFORE NEXT ROUND OF
STORMS MONDAY...MAINLY ALONG AND EAST OF A KMCW TO KDSM LINE.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...REV
LONG TERM...PODRAZIK
AVIATION...FAB
000
FXUS63 KDVN 200014
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
714 PM CDT SUN MAY 19 2013
.SYNOPSIS...
ISSUED AT 322 PM CDT SUN MAY 19 2013
CONDITIONS COMING TOGETHER THIS AFTERNOON AND EVENING FOR A
SEVERE WEATHER OUTBREAK AND TORNADO WATCHES ARE IN PLACE FOR LATE
THIS AFTERNOON AND EVENING FOR ALL BUT THE EASTERN THIRD OF THE
FORECAST AREA. THESE INGREDIENTS INCLUDE TEMPERATURES IN THE
80S...DEWPOINTS IN THE UPPER 60S TO LOWER 70S. MID LEVEL SPEED MAX
ROTATING AROUND THE BASE OF A DEVELOPING UPPER LOW OVER THE PLAINS
WILL INCREASE DEEP SHEAR AS IT APPROACHES THIS EVENING. NUMEROUS
MESOSCALE OUTFLOW BOUNDARIES AND AN AXIS OF PRESSURE FALLS ALSO
SIGNAL IMPENDING DEVELOPMENT OF STORMS.
&&
.SHORT TERM...(THIS EVENING THROUGH MONDAY)
ISSUED AT 322 PM CDT SUN MAY 19 2013
A SOMEWHAT SHORTENED DISCUSSION THIS AFTERNOON DUE TO DEVELOPING
SIGNIFICANT WEATHER. FOCUS FOR BOTH SHORT TERM INTO THE EARLY
PERIODS OF THE LONG TERM REMAINS ON THUNDERSTORMS AND POTENTIAL FOR
SEVERE WEATHER.
THIS AFTERNOON INTO THIS EVENING...THE INITIAL DEVELOPMENT WILL
LIKELY BE ALONG A NORTH-SOUTH BOUNDARY BISECTING IA JUST WEST OF
THE FORECAST AREA. AXIS OF PRESSURE FALLS FROM NE MO...ADJACENT W
CENTRAL IL NORTHWARD INTO EASTERN IA SIGNALS AN AREA OF
DESTABILIZATION IN THE CLEARING AND WAKE OF STORMS MOVING INTO SW
WI. SEVERE STORMS INITIALLY OVER THIS AREA THIS EVENING WILL
LIKELY TRANSITION INTO A LARGER MCS...EXITING TO THE EAST-
NORTHEAST...FOLLOWING SYNOPTIC FORCING OF A SHORTWAVE LIFTING OUT
OF THE CENTRAL PLAINS.
AS MENTIONED IN PREVIOUS DISCUSSIONS...INGREDIENTS REMAIN IN PLACE
FOR SEVERE WEATHER FOR MONDAY WITH THE ADDITION OF STRONGER DEEP
LAYER SHEAR TO SUPPORT SUPERCELLS AND TORNADOES. THE FOCUS AND
TRIGGER FOR STORMS WILL AGAIN BE CENTERED ON A MID LEVEL WAVE
LIFTING OUT OF THE SOUTHWEST AND ITS INTERACTION WITH MESOSCALE
BOUNDARIES. TEMPERATURES SHOULD AGAIN REACH INTO THE 80S WITH
DEWPOINTS IN THE UPPER 60S TO LOWER 70S. SPC CURRENTLY HAS A SLIGHT
RISK IN PLACE FOR DAY 2.
.LONG TERM...(MONDAY NIGHT THROUGH SUNDAY)
ISSUED AT 322 PM CDT SUN MAY 19 2013
ALTHOUGH NOT AS IDEAL AS TODAY OR MONDAY...SEVERE WEATHER WILL AGAIN
BE POSSIBLE TUESDAY AND SPC HAS A SLIGHT RISK OVER THE AREA FOR DAY
3. OTHERWISE...THE OVERALL TREND IN THE EXTENDED FORECAST IS TOWARD
MORE STABLE...NOT AS WARM...AND DRIER WEATHER LATE WEEK AS THE
PLAINS LOW WEAKENS AND MOVES OUT...REPLACED BY HIGH PRESSURE. MODELS
CONTINUE TO DIVERGE SOME WITH HOW QUICKLY THE RIDGE MOVES OUT BY
NEXT WEEKEND AND THE TIMING OF A WARM FRONT THAT MAY BRING RAIN
CHANCES BY LATE SATURDAY AND ESPECIALLY SATURDAY NIGHT AND MONDAY.
&&
.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 642 PM CDT SUN MAY 19 2013
LOW PRESSURE STALLING OVER MN FOR THE NEXT FEW DAYS WILL KEEP
ACTIVE WEATHER OVER THE AREA THROUGH MONDAY AFTERNOON. WE SHOULD
SEE ANOTHER ROUND OR TWO OF THUNDERSTORMS THE REST OF THE TONIGHT
OVER THE FORECAST AREA. THE BEST COVERAGE LATE THIS EVENING AND
OVERNIGHT SHOULD BE WEST OF THE MISSISSIPPI RIVER. WE SHOULD SEE A
BREAK IN THE STORMS LATE TONIGHT AND MONDAY MORNING. THEN STORMS
SHOULD REDEVELOP DURING THE AFTERNOON WITH A THREAT OF SEVERE
STORMS OVER THE ENTIRE AREA.
DLF
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
AVIATION...DLF
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