Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 042019
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
319 PM CDT FRI SEP 4 2015

.DISCUSSION...
ISSUED AT 319 PM CDT FRI SEP 4 2015

AREA CONTINUES BENEATH SOUTHERLY FLOW IN THE LOWER LEVELS AND AT THE
SURFACE AS THE STATE REMAINS SANDWICHED BETWEEN A LARGE AREA OF HIGH
PRESSURE OVER THE OHIO VALLEY AND A DEVELOPING LOW PRESSURE SYSTEM
STRETCHING FROM CENTRAL ND SOUTHWESTWARD INTO NW KS. WEAK PV
ADVECTION AND THETA-E ADVECTION HAS BEEN IN PLACE JUST TO THE WEST
OF THE CWA THROUGHOUT THE DAY...WHICH HAS RESULTED IN A SMALL AREA OF
SHOWERS AND THUNDERSTORMS ACROSS PORTIONS OF ERN NE...SE SD AND NW
IA. THE AREA OF LIFT IS EXPECTED TO SLOWLY TRANSLATE ACROSS THE
NORTHERN CWA EARLY THIS EVENING AND WILL BE REINFORCED LATE THIS
EVENING INTO THE OVERNIGHT HOURS AS THE LLJ PICKS UP AND IS ORIENTED
INTO NC IA AND CNTRL MN. THEREFORE PRECIP THAT IS CREEPING INTO THE
NW CWA IS EXPECTED TO CONTINUE TO PUSH EASTWARD. EXPECT SOME
DIMINISHMENT WITHIN THE AREA INTO THE MID EVENING HOURS...BUT THEN
ADDITIONAL DEVELOPMENT/ENHANCEMENT EXPECTED WITH THE ONSET OF THE
LLJ WITH STORMS EXPECTED TO REMAIN SUB-SEVERE. SOUTHERLY FLOW
CONTINUES TO INCREASE INTO SATURDAY/SUNDAY AS THE UPPER TROUGH OVER
THE PAC NW PUSHES THROUGH THE NORTHERN ROCKIES AND INTO SRN
SASKATCHEWAN/MANITOBA BY LATE SUNDAY. THE ASSOCIATED AREA OF LOW
PRESSURE WILL REMAIN WILL DEEPEN AND LIFT INTO THE NRN PLAINS/MN
THROUGH THE WEEKEND WITH THE ASSOCIATED COLD FRONT TO BE PUSHING
INTO THE NORTHWESTERN CWA BY SUNDAY AFTERNOON. AHEAD OF THIS FRONT
EXPECT THE WARM AND HUMID WEATHER TO CONTINUE. A FEW WEAK IMPULSES
SHOVE OUT AHEAD OF THE MAIN TROUGH SATURDAY NIGHT INTO SUNDAY WHICH
COULD BRING SOME CHANCES FOR STORMS AHEAD OF THE MAIN FRONTAL
PASSAGE WAA AND WEAK BAROCLINIC ZONE IN PLACE ACROSS THE WESTERN
CWA. OTHERWISE FRONTAL BOUNDARY TO DROP THROUGH THE CWA SUNDAY NIGHT
WITH MORE WIDESPREAD PRECIP CHANCES POSSIBLE. DEEP LAYER SHEAR
INCREASES TO AROUND 30-35 KTS WITH DECENT INSTABILITY...SO SOME
SEVERE STORMS POSSIBLE. FRONTAL BOUNDARY STALLS OUT ACROSS THE
SOUTHERN CWA...SO STORM CHANCES LINGER INTO MONDAY/MONDAY NIGHT AS
WEAK ENERGY CONTINUES TO MOVE THROUGH THE REGION ALOFT. ADDITIONALLY
ACTIVITY POSSIBLE INTO TUE/TUE NIGHT AS A STRONGER WAVE PUSHES
THROUGH IN THE NEAR ZONAL FLOW ALOFT. THIS WILL PUSH THE LINGERING
FRONTAL BOUNDARY TO THE SOUTH OF THE STATE WITH HIGH PRESSURE
BUILDING IN FOR WEDNESDAY. PREVIOUS RUNS THE PAST FEW DAYS HAVE HELD
THIS AREA OF HIGH PRESSURE IN FIRM CONTROL OF THE AREA...BUT BOTH
THE GFS/EC TODAY HAVE ANOTHER SHORTWAVE TROUGH DIGGING INTO THE BACK
OF THE MAIN TROUGH OVER THE NORTHERN PLAINS TOWARD LATE WEEK. THIS
MAY RESULT IN SOME SHOWERS/ISOLATED STORMS WEDNESDAY NIGHT AND MAYBE
INTO THURSDAY. TIMING IS TOUGH AT THIS RANGE WITH SOME
DISCREPANCIES. TEMPERATURES TRENDING COOLER THROUGH THE WEEK STILL
ON TRACK WITH H85 TEMPS DROPPING FROM THE LOWER 20S CELSIUS THIS
WEEKEND INTO THE THE LOW TEENS TO AROUND 10C BY THE END OF THE
WEEK.

&&

.AVIATION...04/18Z
ISSUED AT 139 PM CDT FRI SEP 4 2015

MUCH OF THE SAME AT TAF SITES FOR THE UPCOMING TAF PERIOD AS THE
PREVIOUS DAY OR TWO. SOUTHERLY WINDS AROUND 10KTS DURING DAYTIME
HOURS TODAY AND TOMORROW WITH OCCASIONAL GUSTS TO AROUND 15KTS.
WINDS WILL CALM A BIT TO AROUND 5 KTS THIS EVENING AND CLOUD
COVER WILL MOVE IN FROM THE WEST...BUT VFR CIGS WILL DOMINATE
WITH DECKS NOT EXPECTED TO BE MUCH...IF AT ALL...BELOW 10KFT AT
THE MOMENT.


&&

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

&&

$$

DISCUSSION...BEERENDS
AVIATION...CURTIS



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