Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 262039
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
339 PM CDT WED AUG 26 2015

.SHORT TERM /TONIGHT/...
ISSUED AT 335 PM CDT WED AUG 26 2015

SURFACE RIDGE GRADUALLY SLIDING TO THE EAST OF THE FORECAST AREA
THIS AFTERNOON WITH SOUTHERLY FLOW AND WARM ADVECTION INCREASING IN
WESTERN IOWA.  SMOKE VEIL FROM WESTERN FIRES HAS BEEN OVERHEAD TODAY
ALONG WITH SOME CIRRUS AND MID LEVEL DEBRIS FROM EARLIER CONVECTION
JUST WEST OF THE MISSOURI RIVER.  TIGHT GRADIENT OF MOISTURE EXISTS
TO THE WEST AND THIS WILL BEGIN TO SHIFT SLOWLY EASTWARD OVERNIGHT.
WITH THETA-E ADVECTION APPROACHING THE WEST LATE TONIGHT...SOME
THREAT FOR ISOLD/SCT CONVECTION IS EXPECTED IN THE FAR WEST TOWARD
DAYBREAK AND HAVE INCLUDED LOW POPS IN THAT AREA.  WILL SEE TRANQUIL
WEATHER IN MOST OTHER LOCATIONS OVERNIGHT WITH WARMER TEMPERATURES
WITH THE INCREASING WARM ADVECTION AND HIGHER DEWPOINTS.

.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
ISSUED AT 335 PM CDT WED AUG 26 2015

THURSDAY THROUGH SATURDAY MORNING...SHOWERS AND STORMS TRICKLING
INTO THE AREA THURSDAY MORNING AND RAMPING UP THURSDAY AFTERNOON
THROUGH FRIDAY REMAINS THE PRIMARY...AND REALLY ONLY...STORY OF
CONCERN THROUGH THE LONG TERM.  A RIGOROUS UPPER LEVEL
SHORTWAVE...CURRENTLY PUSHING THROUGH NORTHERN UTAH...WILL CONTINUE
ITS TREK THROUGH THE RIDGE AND FIND ITS WAY INTO THE PLAINS
OVERNIGHT TONIGHT AND INTO THE STATE FRIDAY MORNING.  MODELS ARE IN
PRETTY GOOD AGREEMENT ON PLACEMENT OF THE SURFACE LOW AND
TIMING...WITH THE EURO A BIT FURTHER NORTH THAN THE GFS AND NAM. A
FEW SHOWERS AND STORMS WILL LIKELY MOVE THROUGH WESTERN AND PORTIONS
OF CENTRAL IOWA THURSDAY AFTERNOON/EVENING AHEAD OF THE MAIN SYSTEM
AS A WEAKER PUSH OF THETA-E ADVECTION MOVES THROUGH. THE THREAT FOR
SEVERE WEATHER FRIDAY CONTINUES TO APPEAR WEAK WITH THE BULK OF THE
FORCING PUSHING THROUGH IN THE AM HOURS SPARKING OFF SHOWERS AND
HELPING SUBDUE BUILD UP OF DAYTIME INSTABILITY...EVEN WITH POSSIBLE
0-6KM SHEAR VALUES IN EXCESS OF 40-50M/S THURSDAY THROUGH FRIDAY.
INSTEAD...HEAVY RAINFALL WILL BE OF CONCERN...ESPECIALLY ACROSS
NORTHERN IOWA...AS THE SYSTEM SLINKS ACROSS THE STATE WITH MODELS
PUSHING PWAT VALUES TOWARDS 2.00 INCHES AND FREEZING LEVELS CLOSE TO
14KFT BY THURSDAY EVENING. SOME FLASH FLOODING MAY BE OF
CONCERN...BUT LIKELY ONLY IN AREAS THAT SEE IN EXCESS OF 3.00 INCHES
GIVEN THE LONGER DURATION NATURE OF THE EVENT AND THE HEALTHY CROPS.

SATURDAY THROUGH WEDNESDAY...ONCE THE SYSTEM PUSHES THROUGH THE
STATE AND INTO THE ILLINOIS/WISCONSIN AREA SATURDAY...UPPER LEVEL
RIDGING QUICKLY BUILDS IN BEHIND IT.  AS A RESULT...THE REGION WILL
REMAIN DRY SATURDAY ONWARD BUT THE PLEASANT TEMPERATURES OF THE LAST
FEW DAYS WILL GO TO THE WAYSIDE AS SOUTHERLY WINDS BEGIN TO USHER IN
WARMER TEMPERATURES AND HIGHER DEW POINTS.  WIDESPREAD TEMPERATURES
INTO THE LOW TO MID 80S MONDAY AND INTO THE MID TO UPPER 80S BY
TUESDAY AND WEDNESDAY.

&&

.AVIATION...26/18Z
ISSUED AT 111 PM CDT WED AUG 26 2015

GENERALLY VFR CONDITIONS FOR THE DURATION OF THE FORECAST AS
SURFACE RIDGE PULLS SLOWLY EAST OF THE STATE. SOME MID AND HIGH
LEVEL CEILINGS ARE EXPECTED...ESPECIALLY LATE IN THE FORECAST
PERIOD. IN ADDITION...SOME LIGHT FOG WILL BE POSSIBLE
OVERNIGHT...MAINLY ALONG AND EAST OF A KMCW-KDSM-KLWD LINE.
SURFACE WINDS WILL BE LIGHT AND VARIABLE BECOMING SOUTHEAST ON
THURSDAY.


&&

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

$$

SHORT TERM...COGIL
LONG TERM...CURTIS
AVIATION...COGIL


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