FXUS63 KDMX 252353 AAB
AFDDMX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
552 PM CST FRI DEC 25 2009

..UPDATED AVIATION DISCUSSION...

.SHORT TERM.../TONIGHT/
SFC LOW REMAINS NEAR KFOD AT NOON WITH STRONGEST WINDS ON THE BACK 
SIDE FOR NOW.  AREA OF MODERATE SNOW WILL REMAIN OVER THE WEST UNTIL 
BEST FORCING AND UPPER LEVEL LOW ROTATES ACROSS THE STATE AND AREA 
OF SNOW FOLLOWS THIS EVENING. WILL MAINTAIN HIGH POP AS THE FORCING 
CROSSES CENTRAL AND SOUTHERN SECTIONS ONCE AGAIN. WINDS EXPECTED TO 
MAINTAIN 15 TO 25 MPH RANGE OVER MUCH OF THE WEST...BUT DIMINISH 
OVER THE EAST TNT. WITH MAINLY LIGHT SNOW EAST HAVE DECIDED TO DROP 
SOME COUNTIES IN THE ADVISORY AREA AND DOWNGRADE SOME OTHERS FROM 
WARNING TO WINTER WEATHER ADVISORY. COLD TEMPS TO REMAIN OVERNIGHT 
AS AREA OF COLD AIR NOW WELL MIXED WITH THE LOW OVER THE STATE. 
BANDS OF HEAVY SNOW AND BLOWING SNOW STILL CURLING BACK TOWARD THE 
WESTERN COUNTIES EARLY THIS EVENING. WITH THE COUNTIES WITH HEAVIER 
SNOW AND ICE ACCUMULATION...WILL KEEP WARNING GOING TO AT LEAST 7 
PM. AFTER THAT...WHEN WINDS DIMINISH AND THREAT FOR BLOWING SNOW HAS 
LESSENED...EVENING SHIFT CAN REEVALUATE.   

.LONG TERM.../SATURDAY THROUGH FRIDAY/
UPPER LOW WILL BE SLOW TO MOVE OUT OF THE AREA WITH FUJIWARA TAKING 
PLACE TONIGHT BTWN THE SRN SSY AND THE POLAR LOW.  POLAR LOW WILL 
BECOME DOMINANT AND WHOLE SYS WILL EVENTUALLY MOV EWD.  SUPPORT IS 
WEAKENING WITH TIME.  THOUGH WILL SEE SOME -SN INTO SAT 
NGT...ACCUMULATING SNOW WILL BE OVER WITH BY 00Z/27.  TEMPS WILL 
REMAIN A LTL BLO NORMAL WITH POLAR HIGH PRES BLDG INTO THE CENTRAL 
U.S. FOR THE FIRST PART OF THE WEEK.  WEAK CLIPPER TYPE SYS WILL 
DROP SOUTHEAST AND PASS NORTH OF IA ON WED.  THIS SYS MAY BRING SOME 
LGT SNW TO THE REGION...BUT KEPT POPS IN THE CHC CAT AND DO NOT 
EXPECT TO SEE SIG SNOW FROM THIS SYS.  DO NOT EXPECT TO SEE ARCTIC 
OUTBREAK AFT THIS SYS EITHER AS SPLIT FLOW WILL PREVAIL AND KEEP 
MUCH OF THE ARCTIC AIR N OF 50N.  PTRN IN THE LONGER TERM WILL BE 
DOMINATED BY -NAO PTRN AND NOT MODIFIED A GREAT DEAL BY THE WEAK MJO 
PROGRESSION.  EL NINO PTRN IS EVIDENT WITH THE EAJ SETTING UP AGAIN 
AND THE SPLIT FLOW...HOWEVER WITH THE OLR CENTER SHIFTED WEST OF 
WHAT IS TYPICAL THE CHINOOK EFFECT IS DIMINISHED AND WILL REMAIN SO 
FOR THE TIME BEING.

&&

.AVIATION...
26/00Z...WITH SFC LOW PRESSURE CENTER CURRENTLY OVER NW IA...AND 
EXPECTED TO LOOP SOUTH TONIGHT THEN EAST ACROSS SRN IA SAT 
MORNING...SWIRL OF IFR/MVFR CEILINGS AND PERIODS OF GENERALLY LIGHT 
SNOW CAN BE ANTICIPATED THROUGH MUCH OF THE PERIOD. CEILINGS MAY 
ACTUALLY FLUCTUATE OVER FL030 AT TIMES...BUT SHOULD REMAIN LARGELY 
BELOW THAT LEVEL. IT SEEMS THAT SRN SITES LIKE KDSM AND KOTM WILL 
HAVE THE LOWEST FLIGHT CONDITIONS AND MOST PREVALENT SNOWFALL WHILE 
NORTHERN SITES MAY EXPERIENCE LONGER VSBY RANGES. CONFIDENCE NOT 
HIGH REGARDING RISING CEILINGS LATE IN THE PERIOD...SO LEFT THEM IN 
THE 015-025 RANGE.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...

WINTER STORM WARNING UNTIL 6 AM CST SATURDAY FOR 
AUDUBON-CALHOUN-CARROLL-CRAWFORD-EMMET-PALO ALTO-POCAHONTAS-SAC.

WINTER WEATHER ADVISORY UNTIL 6 AM CST SATURDAY FOR 
ADAIR-ADAMS-APPANOOSE-BOONE-CASS-DALLAS-DAVIS-DECATUR-FRANKLIN-GREENE
-GUTHRIE-HAMILTON-HARDIN-HUMBOLDT-JASPER-KOSSUTH- 
LUCAS-MADISON-MAHASKA-MARION-MONROE-POWESHIEK-POLK-RINGGOLD-STORY-
TAYLOR-UNION-WAPELLO-WARREN-WAYNE-WEBSTER-WINNEBAGO-WRIGHT.

&&

$$

SHORT TERM...REV
LONG TERM...MS DEC 09
AVIATION...MOYER