Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 302056
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
356 PM CDT SAT AUG 30 2014

.SHORT TERM /TONIGHT/...
ISSUED AT 356 PM CDT SAT AUG 30 2014

WEAK ENERGY STILL WRAPPING AROUND THE UPPER LEVEL SHORT WAVE OVER
MINNESOTA AND WISCONSIN AND INTO NORTHEAST IOWA THIS AFTERNOON. THIS
HAS LED TO A FEW SHOWERS TO DEVELOP OVER THAT REGION. THE STRATUS
FIELD CONTINUES TO ERODE OVER CENTRAL IOWA LEADING TO SOME SFC BASED
INSTABILITY TO DEVELOP. HI RESOLUTION SOLUTIONS THROUGH THE
AFTERNOON ARE SUGGESTING ISOLATED THUNDERSTORM DEVELOP ALONG AND
EAST OF INTERSTATE 35 LATE AFTERNOON THROUGH EARLY EVENING AS A
SURGE OF THETA-E ADVECTION MOVES INTO THE STATE. THE LIMITING FACTOR
IS THE VERY DRY MID LEVELS AND ONLY WEAK VERTICAL ASCENT. POSSIBLE
FOR AN ISOLATED THUNDERSTORM TO DEVELOP OVERNIGHT BEFORE ENDING.
IMPRESSIVE UPPER JET MOVING INTO THE WESTERN CONUS WILL BEGIN TO
APPROACH THE MISSOURI VALLEY LATE TONIGHT. A THUNDERSTORM COMPLEX
FROM THE WEST MAY REACH EASTERN NEBRASKA AND POSSIBLY FAR WESTERN
IOWA BY 12Z BUT THE AREA SHOULD REMAIN DRY THROUGH THAT TIME.


.LONG TERM /SUNDAY THROUGH SATURDAY/...
ISSUED AT 356 PM CDT SAT AUG 30 2014

MAIN FOCUS IN THE EXTENDED WILL BE ON SUNDAY INTO SUNDAY NIGHT WITH
STRONG UPPER LEVEL WAVE DIGGING INTO THE INTERMOUNTAIN WEST AND
PUSHING THROUGH THE REGION LATE SUNDAY INTO SUNDAY NIGHT. SOUTHERLY
FLOW INCREASES AHEAD OF THE WAVE WITH THE SFC TROUGH AXIS SITUATED
JUST TO THE WEST OF THE STATE BY SUNDAY AFTERNOON. WEAK ENERGY ALOFT
AHEAD OF THE MAIN WAVE TO MOVE THROUGH DURING THE DAY WITH SOME WEAK
THETA E ADVECTION...SO SOME ISOLATED SHOWERS/THUNDERSTORMS POSSIBLE
ACROSS THE NORTH MAINLY IN THE AFTERNOON. OTHERWISE STRONGER FORCING
EXPECTED AS MAIN SHORTWAVE APPROACHES WITH STRONGER LOW LEVEL
CONVERGENCE AND THETA E ADVECTION SUGGEST GREATEST CHANCE FOR
THUNDERSTORM ACTIVITY TO BE TOWARD MID/LATE EVENING INTO THE
OVERNIGHT HOURS AS THE THE TROUGH AXIS/COLD FRONT PUSHES THROUGH THE
STATE. DECENT CAPE/SHEAR SUGGEST POTENTIAL FOR ALL MODES OF SEVERE
WEATHER...WITH A THREAT OF HEAVY RAIN ALSO POSSIBLE. PWATS EXPECTED
TO BE IN THE 1.5 TO 1.9 INCH RANGE ACROSS THE CWA. STORM MOTIONS
ALSO EXPECTED ON THE SLOWER SIDE AT AROUND 20 TO 25 KTS WITH A
SOMEWHAT HIGHER FREEZING LEVEL. ALSO LOOKS LIKE A FEW ROUNDS OF
STORMS COULD IMPACT THE NORTH...SO WILL HAVE TO MONITOR FOR HYDRO
CONCERNS AS WELL. SYSTEM QUICKLY MOVES THROUGH THE AREA LATE SUNDAY
NIGHT...WITH MAYBE A FEW LINGERING STORMS IN THE EAST EARLY MONDAY.
HIGH PRESSURE BUILDS INTO THE STATE BRIEFLY INTO THE STATE FOR
MONDAY...BUT OVERALL PATTERN REMAINS SOMEWHAT ACTIVE THROUGH THE
REMAINDER OF THE WEEK INTO EARLY NEXT WEEKEND WITH FAST WESTERLY TO
SOUTHWESTERLY FLOW AND WEAK IMPULSES MOVING THROUGH ALOFT. TEMPS
ALOFT WARM INTO MID/LATE WEEK WHEN ANOTHER COLD FRONT DROPS THROUGH
THE STATE THURSDAY INTO THURSDAY NIGHT...WITH THE FRONT STALLING
JUST TO THE SOUTH OF IOWA...AND THEN PUSHING BACK NORTH AS A WARM
FRONT TOWARD WEEKEND INTO EARLY NEXT WEEK. MAX TEMPS EXPECTED TO BE
MAINLY IN THE 80S WITH OVERNIGHT LOWS IN THE 60S TO AROUND 70.


&&

.AVIATION...30/18Z
ISSUED AT 1236 PM CDT SAT AUG 30 2014

MVFR STRATUS DECK REMAINS EXPANSIVE ACROSS CENTRAL IOWA THOUGH IT
IS GRADUALLY LIFTING AND BECOMING MORE CELLULAR. THE STATUS SHOULD
CONTINUE TO ERODE FROM THE WEST THROUGH THE AFTERNOON AND EARLY
EVENING. SOME POTENTIAL FOR FOG OVERNIGHT BUT CHANCE NOT HIGH
ENOUGH YET TO INCLUDE IN THE FORECAST. BREEZY SOUTHERLY WINDS
DEVELOP SUNDAY MORNING UNDER VFR CONDITIONS.


&&

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

&&

$$

SHORT TERM...DONAVON
LONG TERM...BEERENDS
AVIATION...DONAVON



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