FXUS63 KDMX 300540
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1139 PM CST SUN NOV 29 2009

.SHORT TERM /TONIGHT/...
UPPER LEVEL TROUGH AXIS TO PASS EAST OF CENTRAL IOWA BY MID EVENING 
AND THIS WILL HELP TO SHUNT THE REMAINING PESKY LOW CLOUDS TO THE 
EAST. SFC HIGH PRESSURE WILL PASS OVER IOWA TONIGHT...BUT ITS AXIS 
WILL QUICKLY MOVE SOUTH OF THE AREA BY 12Z. SHOULD HAVE A WINDOW OF 
OPPORTUNITY IN THE FIRST HALF OF THE NIGHT WHERE IT CLEARS TO SEE 
TEMPS DROP QUICKLY BEFORE LIGHT WEST TO SOUTHWEST FLOW SETS IN. NW 
SECTIONS MAY EVEN GET UNDER SOME MID LEVEL WARM ADVECTION CLOUDS 
LATE TONIGHT. GENERALLY WENT A DEGREE OR TWO UNDER A MAV/MET COMBO 
FOR MIN TEMP. 

.LONG TERM /MONDAY THROUGH SUNDAY/...
FIRST FEW DAYS OF THE EXTENDED WILL BE STRAIGHT FORWARD AS COLD 
AIRMASS GIVES WAY TO MODIFICATION FOR THE MED RANGE.  WARMING INTO 
MONDAY AND TUESDAY AS SHORT WAVE TRACKS ACROSS USCAN BORDER NEAR 
DULUTH ON TUESDAY AFTERNOON. AIRMASS WILL NOT SUPPORT ANY PRECIP AS 
SFC DEW POINTS AND UPPER LEVEL MOISTURE FIELDS REMAIN TOO DRY AND 
THE MAIN FRONTAL BOUNDARIES NORTH AND WEST OF THE REGION. WARM AIR 
AHEAD OF TUESDAY SYSTEM DOES NOT LOOK QUITE AS STRONG AS THE 
PREVIOUS RUN OF THE GFS AND H850 TEMPS NOT AS WARM AS YESTERDAY 
AFTERNOONS...SO HAVE TRIMMED HIGHS ON TUESDAY A BIT.  AS THE COLD 
FRONT DROPS SOUTH INTO THE STATE TUESDAY AFTERNOON TEMPS WILL FALL 
QUITE DRAMATICALLY IN THE NEXT 24 HOURS. MODELS IN GOOD AGREEMENT 
INITIALLY WITH LARGE...COLD...H500 TROUGH DEEPENING OVER THE 
NORTHERN PLAINS AND GREAT LAKES FOR WED NIGHT THROUGH EARLY FRIDAY. 
THIS SHOULD USHER IN SOME OF THE COLDEST TEMPS OF THE SEASON SO FAR 
WITH SNOW SHOWERS OR FLURRIES THURSDAY...ESPECIALLY NORTHEAST. SOME 
TIMING ISSUES BEGIN TO REAR UP FOR THE WEEKEND... BASICALLY MAKING 
MUCH OF THE FORECAST BEYOND FRIDAY LOW CONFIDENCE FOR NOW. THE 00Z 
GEM AND EURO MODELS ARE MAINTAINING A HIGHER AMPLITUDE RIDGE OVER 
THE INTERMOUNTAIN REGION/WEST COAST THROUGH 12Z FRIDAY WHILE THE 12Z 
GFS HAS ALREADY BOTH CREATED A FLATTER RIDGE AND MORE PROGRESSIVE 
RIDGE AXIS. MANY FEATURES REMAIN OUT OF PHASE AS THE MODELS BEGIN TO 
EVOLVE INTO THE WEEKEND. THE MAIN PLAYER FOR ANY PRECIP HERE IS WELL 
OFF THE WEST COAST BY EARLY FRIDAY. THE EURO/GFS SHOW A H500 
LOW/UPPER LEVEL TROUGH ARRIVING ALONG THE PACNW BY 00Z SAT WITH THE 
GEM HAVING A STRONGER LOW DROPPING SOUTHEAST INTO THE NORTHERN 
ROCKIES AND CUTTING OFF BY HR144. INTO THE WEEKEND THE GFS AND GFS 
ENSEMBLE COMPLETELY GOES ZONAL WITH THE WEST COAST TROUGH DIGGING.  
THIS QUICKLY DEVELOPS A SOUTHWEST FLOW ALOFT AND DRIVES SEVERAL SFC 
FEATURES TOWARD THE PLAINS OVER THE WEEKEND. THE EURO HANGS THE H500 
FEATURE UP ALONG THE BRITISH COLUMBIA COAST...MAINTAINING A MORE 
PRONOUNCED SPLIT FLOW THROUGH HR204 AND THEN BREAKS THE PATTERN DOWN 
INTO A ZONAL FLOW. THIS EURO CUTOFF LOOKS SOMEWHAT SUSPECT BUT DOES 
FAVOR A MORE EL NINO SPLIT FLOW ACROSS THE CONUS INTO THE WEEKEND 
AND EARLY NEXT WEEK. THE CONFIDENCE LEVEL IN DAYS5 THROUGH 7 REMAINS 
LOW AND WILL NEED SOME ADJUSTMENTS OVER THE NEXT SEVERAL PACKAGES. 
WITH THE SURROUNDING OFFICE CONSENSUS TO LEAN TOWARD A DRY AND 
SEASONAL FORECAST THIS WEEKEND...HAVE TRENDED TOWARD THE EURO MODEL 
FOR NOW. IF THE GFS/GEM SOLNS CONTINUE TO SHOW VALIDITY...NEXT 
WEEKEND MAY OFFER A RATHER COMPLICATED MIX OF PTYPES FOR THE AREA. 

&&

.AVIATION...
30/06Z...VFR WITH AREAS OF MVFR CIGS SLOWER TO EXIT THAN THOT 
EARLIER...BUT WILL MOV OUT OF ALL OF THE TAF SITES BY ARND 12Z.  
BACK EDGE ARND KFOD 08Z...KDSM-KALO ARND 10Z...AND IN THE KOTM AREA 
ARND 12Z.  NWLY FLOW BCMG WSWLY FOR MON INTO MON EVEN  ONLY MID AND 
HI SCT-BKN CLOUDS AFT 12Z/30.

&&

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

&&

$$

SHORT TERM...MS NOV 09
AVIATION...MS NOV 09
LONG TERM...REV