Area Forecast Discussion
Issued by NWS Des Moines, IA

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FXUS63 KDMX 301126
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
626 AM CDT THU OCT 30 2014

.SHORT TERM /TODAY/...
ISSUED AT 345 AM CDT THU OCT 30 2014

A WEAK LOW PRESSURE TROUGH MOVING OVER THE AREA IS PRODUCING MID
LEVEL CLOUDS AND A FEW SPRINKLES PER REGIONAL SATELLITE AND RADAR
IMAGERY. THESE CLOUDS/SPRINKLES WILL PROGRESS EASTWARD THROUGH THE
MORNING...CLEARING THE FORECAST AREA BY THE AFTERNOON. HAVE GONE
WITH ISOLATED SPRINKLE WORDING TO HANDLE THE PRECIP BUT MOST WILL
NOT EVEN REACH THE GROUND. LATE IN THE DAY A SURGE OF WIND AND
COOLER AIR WILL ENTER IOWA FROM THE NORTH IN ADVANCE OF A LARGE COLD
HIGH PRESSURE SYSTEM SET TO AFFECT THE REGION OVER THE FOLLOWING
COUPLE OF DAYS. HAVE INCLUDED THE WIND SURGE IN OUR NORTHERN
COUNTIES LATE TODAY BUT MOST OF THE COOLER TEMPERATURES WILL FLOW IN
AFTER 00Z AND HAVE LEFT THEM TO THE TONIGHT FORECAST.

.LONG TERM /TONIGHT THROUGH WEDNESDAY/...
ISSUED AT 345 AM CDT THU OCT 30 2014

ALTHOUGH THE PATTERN WILL BE SOMEWHAT ACTIVE THROUGH THE
PERIOD...THERE ARE ONLY A FEW WINDOWS OF SENSIBLE WEATHER NEEDING
ATTENTION. CURRENT SYSTEM BRINGING LIGHT MAINLY ELEVATED PRECIP TO
IA/MN SHOULD BE SOUTH AND EAST OF IA BY 00Z WITH ATTENTION TURNING
UPSTREAM. MANITOBA SHORT WAVE WILL STRENGTHEN AS IT REACHES THE
GREAT LAKES TONIGHT WITH IMPRESSIVE SUBSIDENCE/LIFT COUPLET WHOSE
SWRN FRINGE WILL JUST BRUSH IA. MOISTURE WILL BE LIMITED BEHIND
THE INITIAL WAVE HOWEVER AND THERE MAY BE SOME CLOUDINESS DURING
THE EVENING AND POSSIBLY A FEW SPRINKLES WHICH WILL NOT BE IN THE
FORECAST. STRONG SUBSIDENCE WILL THEN DROP DOWN THE MS VALLEY BY
06Z WITH STRONG COLD ADVECTION. THIS WILL INDUCE SHALLOW NOCTURNAL
MIXING WITH NORTH AND EAST SECTIONS POSSIBLY SEEING GUSTS TO 30KTS
PER 500M WINDS. A 30 DEGREE DROP FROM THU MAXES TO FRI MORNING
MINS ARE EXPECTED WITH FRI HIGHS ONLY A FEW DEGREES EITHER SIDE OF
40F.

PATTERN AMPLIFICATION AND HIGH PLAINS UPPER RIDGE WILL DRIVE SURFACE
HIGH REFLECTION INTO IA BY FRI NIGHT.  WIDESPREAD LOWS IN THE 20S
ARE ANTICIPATED WITH ONLY INCREASING CIRRUS KEEPING MINS OUT OF THE
TEENS. RETURN FLOW/WARM ADVECTION WILL DEVELOP SAT AND PERSIST
INTO SUN BUT WITH INSUFFICIENT MOISTURE FOR MUCH IN THE WAY OF
PRECIPITATION. CANNOT RULE OUT ISOLATED LIGHT SHOWERS...BUT WILL
KEEP FORECAST DRY. PRECIP CHANCES WILL THEN INCREASE INTO NEXT
WEEK...BUT ADEQUATE FORCING AND MOISTURE WILL HAVE DIFFICULTY
PHASING WITH MAIN FORCING WITH UPPER LOW REMAINING NW OF IA.
HOWEVER PERSISTENT SW UPPER LEVEL FLOW WITH PERIODS OF LIFT...AND
EVENTUAL H85/H7 WAVE PASSAGE SHOULD EVENTUALLY PRODUCE PRECIP SO
HAVE LOW END POPS STARTING SUN NIGHT AND PEAKING MON AND MON
NIGHT. THIS WOULD MAINLY BE A LOW QPF EVENT WITH MORE SUBSTANTIAL
RAINS INTO MO AND IL...ONLY JUST BRUSHING FAR SERN SECTIONS IF GFS
COMES TO FRUITION.

ECMWF AND GFS DIFFER ON HOW PATTERN WILL EVOLVE BEHIND THE
TROUGH PASSAGE FOR THE MIDDLE TO LATTER PORTIONS OF NEXT
WEEK...GFS MORE AMPLIFIED AND ECMWF MORE ZONAL...BUT NEITHER
SUGGESTS POPS ARE WARRANTED KEEPING MUCH OF TUE AND WED DRY WITH
SEASONAL TEMPS.

&&

.AVIATION...30/12Z
ISSUED AT 626 AM CDT THU OCT 30 2014

A MOSTLY QUIET AVIATION FORECAST IS IN STORE FOR THE NEXT 24
HOURS. A COLD FRONT WILL THEN SURGE SOUTHWARD ACROSS IOWA
LATER TODAY...BRINGING BRISK AND GUSTY NORTH BREEZES ALONG WITH
SOME LOWER CLOUDS AND POTENTIALLY MVFR CIGS MAINLY AFTER DARK.

&&

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

&&

$$

SHORT TERM...LEE
LONG TERM...SMALL
AVIATION...LEE



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