Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 312018
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
318 PM CDT FRI OCT 31 2014

.SHORT TERM /TONIGHT/...
ISSUED AT 314 PM CDT FRI OCT 31 2014

OTHER THAN BEING ONE OF THE COLDEST NIGHTS OF THE SEASON...THE
WEATHER WILL BE BENIGN. HIGH PRESSURE BOTH AT THE SURFACE AND
ALOFT WILL DRIFT OVER IOWA. WINDS WILL DIMINISH TO UNDER 5 MPH
AND WITH CLEAR SKIES THERE WILL BE EXCELLENT RADIATIONAL COOLING
TONIGHT. DROPPED OVERNIGHT LOWS ANOTHER DEGREE OR SO MAINLY ACROSS
THE NORTH AND THE NISH VALLEY AND WE MAY STILL BE TOO WARM
ELSEWHERE BUT CONFIDENCE IS NOT HIGH ENOUGH TO LOWER ELSEWHERE.
TOWARDS 12Z WIND OVER MOST OF THE FORECAST AREA WILL SWITCH TO THE
SOUTHEAST. ALTHOUGH WINDS WILL BE LIGHT THEY MAY BE ENOUGH TO AT
LEAST LEVEL TEMPS OUT TOWARDS DAYBREAK. ONE THING OF NOTE...I DO
EXPECT TEMPS TO FALL QUICKLY THIS EVENING TO FREEZING OR BELOW SO
PEOPLE WILL NEED TO DRESS WARMLY FOR ANY OUTDOOR ACTIVITY.

.LONG TERM /SATURDAY THROUGH FRIDAY/...
ISSUED AT 314 PM CDT FRI OCT 31 2014

MAIN FORECAST ISSUE DEALT WITH PRECIP CHANCES MONDAY INTO TUESDAY
AND WINDS/TEMPS SUNDAY. LEANED TOWARD THE WARMER ECMWF/SREF
SATURDAY AND SUNDAY...THEN SLIGHTLY MORE WEIGHT TOWARDS THE ECMWF
THE REST OF THE FORECAST PERIOD. HOWEVER...THE GFS/CANADIAN ARE
IN GOOD AGREEMENT WITH THE ECMWF TRENDS THROUGH MUCH OF NEXT WEEK.

SATURDAY AND SUNDAY...LARGE SURFACE HIGH PRESSURE WILL DOMINATE
THE WEATHER PATTERN AS IT SLOWLY MIGRATES EASTWARD THROUGH THE
WEEKEND. RETURN FLOW LOOKS TO BEGIN LATE SATURDAY AFTERNOON AND
GRADUALLY INCREASES SATURDAY NIGHT INTO SUNDAY. NORTHWEST
PORTIONS OF THE FORECAST AREA WILL BE FAIRLY WINDY BOTH
DAYS...WITH SUNDAY BEING THE WINDIEST DAY ACROSS THE ENTIRE
FORECAST AREA. ON SUNDAY...WINDS ATOP THE MIX LAYER RANGE FROM
35-40 KNOTS AND THE SURFACE PRESSURE GRADIENT INCREASING AHEAD OF
NEXT LOW PRESSURE SYSTEM DEVELOPING OVER THE CENTRAL TO NORTHERN
PLAINS. TWEAKED WINDS UP SLIGHTLY ON SUNDAY AS WELL AS MAX
TEMPS...MAINLY ACROSS THE SOUTHWEST WHERE SHOULD BE A WARMER START
AS WAA DEVELOPS PAST 06Z SUNDAY IN THAT AREA. POTENTIAL FOR NON-
DIURNAL TEMPERATURE TREND THE FAR SOUTHWEST SATURDAY NIGHT INTO
SUNDAY...BUT LEFT OUT MENTION ATTM AS IT LOOKS TO BE FAIRLY
SUBTLE.

MONDAY INTO TUESDAY...LOW-LEVEL THETA-E ADVECTION COMBINED WITH
SOME WEAK ISENTROPIC LIFT ALONG THE 290-300K SURFACE MOVES ACROSS
CENTRAL IOWA AFTER 06Z MONDAY AND CONTINUES THROUGH MUCH OF THE
DAY MONDAY. PULLED BACK TIMING OF POPS UNTIL AFTER 12Z MONDAY
FOR THE ENTIRE CWA AND EVEN STILL HAVE LOW CONFIDENCE WITH ANY
WIDESPREAD RAIN WITH A DECENT AMOUNT OF DRY AIR IN PLACE ABOVE
800MB. THE STRONGER FORCING AND MOISTURE LOOKS TO POOL OVER THE
SOUTHERN AND EASTERN PORTIONS OF THE FORECAST AREA BY MONDAY NIGHT
WITH THE TROUGH/COLD FRONT PUSHING THROUGH THE STATE. SYSTEM
QUICKLY MOVES EAST AFTER 12Z TUESDAY AND LOWERED POPS ACROSS THE
SOUTHEAST TUESDAY.

WEDNESDAY THROUGH FRIDAY...NORTHWEST FLOW ALOFT LOOKS TO PERSIST
THE REST OF THE WORK WEEK AND MAY SEE A WEAK SHORTWAVE OR TWO RIDE
THE FLOW SOUTHEAST...BUT TIMING AND LOCATION LOOK TO REMAIN NORTH
AND LEFT DRY FORECAST FOR NOW.

&&

.AVIATION...31/18Z
ISSUED AT 1232 PM CDT FRI OCT 31 2014

HIGH PRESSURE WILL BE IN CONTROL OF THE FORECAST THROUGH SATURDAY.
VFR CONDITIONS ARE FORECAST WITH CLEAR SKIES AND NO OBSCURATIONS. AS
THE HIGH SHIFTS OVER IOWA WINDS WILL BECOME LGT AND VARIABLE THEN AS
THE HIGH BEGINS TO SHIFT EAST ON SATURDAY THE WIND WILL SWITCH TO
THE SOUTHEAST AT 10-15KTS.

&&

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

&&

$$

SHORT TERM...FAB
LONG TERM...PODRAZIK
AVIATION...FAB



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