Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 032336
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
636 PM CDT TUE MAY 3 2016

.SHORT TERM.../TONIGHT/
ISSUED AT 303 PM CDT TUE MAY 3 2016

PRIMARY CONCERN TONIGHT WILL BE PRECIPITATION ASSOCIATED WITH
APPROACHING FRONTAL BOUNDARY. PARENT SHORT WAVE WAS JUST DROPPING
THROUGH THE NRN GREAT LAKES WITH DEEP FORCING AND COLD FRONT ALOFT
AIDING LIFT...ALONG WITH LOW LEVEL CONVERGENCE NOTED ALONG COLD
FRONT MOVING THROUGH CENTRAL MN AT 19Z. LOW LEVEL MOISTURE IS QUITE
LIMITED...KEEPING INSTABILITY VERY LOW AND THUNDER POTENTIAL
DOWN...HOWEVER EXPECT THIS CONVECTION TO INTENSIFY A BIT AS IT
BECOMES HIGH BASED BUT SURFACE ROOTED INTO THE EVENING. SOUNDINGS
DEPICT BASES AROUND 6KFT WITH FULL MIXING UNDERNEATH SO THERE MAY BE
SOME SUB SEVERE WIND GUSTS ABOVE AMBIENT LEVELS FROM TIME TO TIME.
THE LATEST RAP AND HRRR BOTH SHOW IT INTENSIFYING SLIGHTLY AS IT
REACHES ERN IA...INCLUDING OUR ERN FORECAST AREA. ANY PRECIPITATION
SHOULD EXIT OVERNIGHT LEADING TO CLEARING SKIES AND SOMEWHAT COOLER
TEMPS AS WINDS SWITCH TO THE NW.

.LONG TERM.../WEDNESDAY THROUGH TUESDAY/
ISSUED AT 303 PM CDT TUE MAY 3 2016

MAIN CHALLENGES OVER THE NEXT 5 DAYS WILL BE TEMPERATURES AND A FEW
MINOR IMPULSES GRAZING THE AREA THROUGH SUNDAY.  BEYOND THAT THE
FOCUS SHIFTS TO LONG WAVE TROUGH NOW OFF THE COAST OF CALIFORNIA
WHICH WILL EVENTUALLY OPEN UP AND BECOME THE PREDOMINANT WEATHER
FEATURE ACROSS THE CENTRAL PLAINS NEXT SUNDAY THROUGH TUESDAY.

SHORT WAVE NOW OVER LAKE SUPERIOR WILL DROP SOUTHEAST OVERNIGHT WITH
TRAILING COOL FRONT OUT OF THE REGION BY 12Z TOMORROW. IN ITS WAKE
H850 TEMPERATURES COOL TO 0C TO 4C NORTHEAST TO SOUTHWEST BY 12Z.
BREEZY WIND WITH 15 TO 25 MPH NORTHWEST FLOW EXPECTED. DESPITE
SOME RECOVERY IN TEMPERATURES ALOFT...OVERALL HIGHS WILL BE SOME 5
TO 7 DEGREES COOLER OVER MOST OF THE AREA EAST OF I35 WHILE WEST
OF I35...TEMPERATURES WILL RECOVER CLOSER TO TODAYS LEVELS INTO
THE AFTERNOON HOURS. RIDGE OF HIGH PRESSURE WILL DRIFT SOUTH JUST
WEST OF THE FORECAST AREA WEDNESDAY NIGHT AND ALLOW LIGHT WINDS
TO SETTLE INTO THE REGION BY 12Z THURSDAY. THIS WILL RESULT IN
STRONG RADIATIONAL COOLING OVER A GOOD SHARE OF THE REGION...
EVEN THOUGH GFS HINTS AT SOME RETURN MID TO HIGH LEVEL CLOUD
COVER OVER THE FAR NORTH SOME 30S WILL BE LIKELY. BY THURSDAY
SHORTWAVE OVER LAKE WINNIPEG MOVES EAST ALLOWING FOR STRONGER
WARM AIR ADVECTION TO BE DRAWN INTO THE PLAINS. WITH LITTLE RETURN
OF MOISTURE...MAIN FOCUS WILL BE ON WARMER TEMPERATURES WITH HIGHS
THURSDAY ALREADY IN THE 60S/70S AND IN THE 70S/80S ON FRIDAY.
MIXING IS MUCH BETTER ON FRIDAY WITH THE APPROACH OF A COOL FRONT
LATE FRIDAY NIGHT. MODELS HAVE BEEN CONSISTENT ON INSTABILITY
INCREASING OVER NORTHERN IOWA AND SOUTHERN MN LATE FRIDAY NIGHT
INTO SATURDAY. AS THE BOUNDARY SHIFTS SOUTH SATURDAY AFTERNOON...
SHOWERS WILL DEPART NORTHERN IA BUT CHANCES FOR THUNDER WILL
REMAIN OVER THE SOUTH TWO THIRDS INTO THE AFTERNOON HOURS.
FORECAST INSTABILITY AND BULK SHEAR LATE SATURDAY AFTERNOON MAY
BE ENOUGH TO DEVELOP A FEW STRONG STORMS ACROSS THE SOUTH DURING
THE AFTERNOON HOURS. GFS BUFR SOUNDINGS SUPPORT ELEVATED
INSTABILITY WITH DECENT HAIL CAPE AT THIS TIME...EURO BULK
SHEAR/MUCAPE SUPPORTIVE OF STRONGER UPDRAFTS. WILL MONITOR FOR
TRENDS NEXT SEVERAL DAYS. OTHERWISE...THE BOUNDARY SLIPS INTO
SOUTHERN MISSOURI BY SUNDAY AFTERNOON AS A STRONGER STORM BEGINS
TO GATHER IN THE WESTERN PLAINS...IN RESPONSE TO THE H500 UPPER
LEVEL TROUGH EXPECTED TO ADVANCE EAST BY THAT TIME. THOUGH
SOLUTIONS DIFFER BETWEEN THE EURO/GFS...MAINLY STANDARD BIASES...
OF TIMING...BOTH MODELS SUGGEST A STRENGTHENING AND MORE ACTIVE
PATTERN AS THE LONG WAVE TROUGH EVENTUALLY DEEPENS OVER THE
CENTRAL PLAINS IN RESPONSE TO A NORTHERN STREAM SHORT WAVE PHASING
WITH THE SYSTEM. THIS WILL PROMOTE A MORE PROLONGED PERIOD OF
RAINFALL...WITH SEVERAL CHANCES FOR THUNDER FROM SUNDAY NIGHT
THROUGH THE END OF THE PERIOD. A CURSORY LOOK AT WIND FIELDS AND
INSTABILITY SUGGESTS THAT SOME STRONGER STORMS WILL BE POSSIBLE
ACROSS OUR AREA...BUT CONFIDENCE ON TIMING/PLACEMENT REMAINS LOW
AT THIS TIME. TEMPERATURES FROM SATURDAY THROUGH TUESDAY WILL
REMAIN MILD...60S AND 70S WILL BE COMMON FOR HIGHS WITH LOWS IN
THE 40S AND 50S.

&&

.AVIATION.../FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING/
ISSUED AT 636 PM CDT TUE MAY 3 2016

WESTERLY WINDS TO SHIFT AROUND TO THE NORTHWEST TO NORTH BEHIND A
COLD FRONT DROPPING SOUTH THROUGH THE STATE THIS EVENING. AN
ISOLATED SHOWER MAY PUSH THROUGH KMCW...KALO...AND KFOD WITH THE
FRONTAL PASSAGE. SOME LOW VFR CU MAY DEVELOP WEDNESDAY AFTERNOON
WITH BASES NEAR SCT-BKN050.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...SMALL
LONG TERM...REV
AVIATION...BEERENDS


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