FXUS63 KDMX 100331 AAA
AFDDMX
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
931 PM CST WED DEC 9 2009
.UPDATE...
WINDS HAVE DROPPED OFF CONSIDERABLY ACROSS MUCH OF CENTRAL
IOWA...WITH MANY LOCATIONS ACROSS THE SOUTHWEST HALF NOW LESS THAN
10 KTS. NOT REALLY HAVING ANY VSBY RESTRICTIONS OF CONSEQUENCE
NOTED VIA OBSERVATION SITES AND WEB CAMS. THERE IS LIKELY STILL
SOME SPOTS EXPERIENCING LOW DRIFTING SNOW...BUT DO NOT BELIEVE
VISIBILITY RESTRICTIONS ARE LOW OR WIDESPREAD ENOUGH TO WARRANT
CONTINUING THE WINTER WEATHER ADVISORY. HOWEVER...WIND CHILL
READINGS ARE ALREADY IN THE 15 TO 25 BELOW RANGE ACROSS THE
CWA...SO WILL CERTAINLY CONTINUE THE WIND CHILL ADVISORY WITH
THOSE READINGS EXPECTED TO BE 20 TO 30 BELOW AFTER MIDNIGHT.
&&
.PREV DISCUSSION... /ISSUED 522 PM CST WED DEC 9 2009/
SHORT TERM /TONIGHT/...
THE STORM SYSTEM IS DEPARTING BUT WE WILL STILL HAVE SOME
HEADLINES OUT FOR VARIOUS CONDITIONS. THE WIND WILL BE RATHER
BRISK THIS EVENING EVEN AFTER DIMINISHING BY 10 PM. BLOWING SNOW
IS STILL LIKELY AND RURAL AREAS MAY STILL HAVE REDUCED
VISIBILITIES THIS EVENING SO I DECIDED TO GO WITH A WINTER WEATHER
ADVISORY TO COVER THE COMBINATION OF BLOWING SNOW AND BITTER COLD
WIND CHILLS AS STRONG COLD ADVECTION CONTINUES TO POUR INTO
CENTRAL IOWA. OVERNIGHT I EXPECT THE WIND TO DIMINISH ENOUGH SO
THAT BLOWING SNOW WILL NOT BE ENOUGH TO REDUCE VISIBILITIES TO
CRITICAL LEVELS BUT WIND CHILLS WILL CONTINUE TO PLUMMET TO 20 TO
30 BELOW OVER THE CWA. AS A RESULT WE WILL GO WITH A WIND CHILL
ADVISORY OVERNIGHT AS THE MAIN THREAT SHIFTS. WIND CHILLS ARE NOT
EXPECTED TO IMPROVE UNTIL MID MORNING THURSDAY SO THE WIND CHILL
ADVISORY WILL REMAIN IN EFFECT UNTIL 10/15Z.
LONG TERM /THU THROUGH WED/...
LITTLE WX OF CONCERN THROUGH THE REMAINDER OF THE WORK WEEK OUTSIDE
OF TEMPS. BROAD LONG WAVE TROUGH REMAINS ENTRENCHED THROUGH MUCH OF
NRN CONUS WITH SFC HIGH PRESSURE CROSSING SRN PLAINS. WITH DEEP
SNOW PACK AND TEMPS MUCH BELOW NORMAL...GUIDANCE WILL STRUGGLE TO
CAPTURE DEGREE OF COOLING SO HAVE GENERALLY GONE BELOW MOS MUCH AS
ALREADY DEPICTED IN GOING FORECAST.
PRIMARY CONCERN HEADING INTO THE WEEKEND INVOLVES MAGNITUDE OF
WARM UP AND POTENTIAL TRANSIENT SYSTEM AROUND SUNDAY. NO
SOLUTION SEEMS TO STICK OUT AS BEING ANY MORE FAVORABLE AT THE
MOMENT SO HAVE PRETTY MUCH BLENDED PREVIOUS FORECAST WITH LATEST
DETERMINISTIC AND ENSEMBLE SOLUTIONS. MODELS ARE NOW MUCH MORE
AGGRESSIVE PUSHING WARMTH AND LOW LEVEL MOISTURE NORTHWARD AHEAD OF
SUNDAY WAVE. MODEL CHANGES ARE EXTREME...AND HAVE NOT GONE AS WARM
AS RAW MODEL TEMPS/DEWPOINTS SUGGEST...BUT HAVE LEANED IN THAT
DIRECTION WARMING TEMPS FOR EARLY NEXT WEEK. THIS INCREASED WARMTH
AND MOISTURE OVER THE SNOW COVER WILL LIKELY LEAD TO STRATUS AND/OR
FOG AT THE LEAST...AND POSSIBLY SOME FREEZING DRIZZLE OR FREEZING
RAIN. MOST LIKELY PERIOD FOR MEASURABLE PRECIP SEEMS TO BE SUN
NIGHT RIGHT NOW SO HAVE RAISED TO CHANCE POPS WITH SNOW AND FREEZING
DRIZZLE MENTION. ADDITIONAL PERIODS OF FREEZING DRIZZLE WORDING MAY
ALSO BE NEEDED AS THE EVENT NEARS.
&&
.AVIATION...
10/00Z...LOWER CLOUDS AND LIGHT SNOW OVER KMCW...KALO AND KOTM WILL
QUICKLY SHIFT EAST BY 02Z. IN ADDITION...NW WINDS WILL BE
DIMINISHING WITH LOSS OF MIXING. SO EXPECT IMPROVING CONDITIONS AT
SITES STILL EXPERIENCING MVFR TO IFR CONDITIONS THIS EVENING. VFR
CONDITIONS TO FOLLOW FOR THE REMAINDER OF THE TAF PERIOD.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
WIND CHILL ADVISORY UNTIL 9 AM CST THURSDAY FOR ADAIR-ADAMS-
APPANOOSE-AUDUBON-BLACK HAWK-BOONE-BREMER-BUTLER-CALHOUN-CARROLL-
CASS-CERRO GORDO-CLARKE-CRAWFORD-DALLAS-DAVIS-DECATUR-EMMET-
FRANKLIN-GREENE-GRUNDY-GUTHRIE-HAMILTON-HANCOCK-HARDIN-HUMBOLDT-
JASPER-KOSSUTH-LUCAS-MADISON-MAHASKA-MARION-MARSHALL-MONROE-PALO
ALTO-POCAHONTAS-POLK-POWESHIEK-RINGGOLD-SAC-STORY-TAMA-TAYLOR-
UNION-WAPELLO-WARREN-WAYNE-WEBSTER-WINNEBAGO-WORTH-WRIGHT.
&&
$$
UPDATE...MOYER
SHORT TERM...FAB
LONG TERM...BSS
AVIATION...MOYER
