FXUS63 KDMX 030529
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
1129 PM CST WED DEC 2 2009

.AVIATION DISCUSSION 03/06Z.

.SHORT TERM [TONIGHT]...
THE NEXT SHORTWAVE IS SWEEPING DOWN ACROSS THE NORTHERN PLAINS AND 
WILL BRUSH NORTHERN IOWA OVERNIGHT. MOISTURE IS SPARSE AND THERE IS 
NO LIFT TO SPEAK OF SO I AM NOT EXPECTING ANYTHING MORE THAN 
FLURRIES OR BRIEF SNOW SHOWERS. SOME LOCATIONS NOTED UPSTREAM WERE 
REPORTING A MILE AND A QUARTER VSBY. THIS SHOULD STAY NORTH OF THE 
STATE. STRATUS/STRATOCU SHIELD IS QUITE EXPANSIVE SO OVERCAST 
CONDITIONS SHOULD PREVAIL WITH MVFR CONDITIONS. LOCAL IFR CONDITIONS 
WILL BE LIKELY IN SNOW SHOWERS. THE OTHER CONDITION TO MENTION IS 
THAT N TO NW WIND WILL REMAIN IN THE 10-20KT RANGE AND BE GUSTY 
THROUGH THE EVENING THEN PICK UP AGAIN AFTER DAYBREAK AS A 
REINFORCING SHOT OF COLD AIR PUSHES IN.

.LONG TERM [THURSDAY THROUGH WEDNESDAY]...
FORECAST FOR NEXT FEW DAYS FIRMLY ON TRACK AS MID/UPPER LOW MOVES 
ACROSS NORTHERN IOWA THURSDAY/THURSDAY NIGHT...ENHANCING COLD AIR 
ADVECTION ACROSS OUR AREA WITH THICK CLOUDS AND PERIODS OF SNOW 
LIKELY. INTENSITY OF SNOW REMAINS LIMITED BY DRY AIR IN THE COLUMN 
AND LESS THAN IMPRESSIVE LIFT...HOWEVER IT APPEARS THAT MOST OF THE 
CWA WILL SEE FLAKES AND A FEW TENTHS OF AN INCH OF ACCUMULATION IS 
POSSIBLE ACROSS MOST OF OUR NORTHERN HALF OR SO WHERE THE MOISTURE 
DEPTH WILL BE GREATER. OVERNIGHT MIXING AND CLOUD COVER WILL HELP TO 
KEEP NIGHTTIME TEMPS UP JUST A BIT...WHILE COLD AIR ALOFT AND CLOUD 
COVER WILL HELP TO KEEP DAYTIME TEMPERATURES DOWN. MADE VERY LITTLE 
CHANGE TO THE FORECAST FOR THE NEXT FEW DAYS.

AFTER A BRIEF QUIET AND SOMEWHAT WARMER PERIOD WITH SOUTHERLY 
LOW-LEVEL FLOW ON SATURDAY...THE NEXT STORM SYSTEM WILL BEGIN TAKING 
SHAPE TO OUR WEST BY SUNDAY. LONG RANGE MODELS ARE IN GOOD GENERAL 
AGREEMENT CUTTING OFF A MID/UPPER LOW OVER THE NORTHWEST U.S. WITH 
MORE OR LESS ZONAL FLOW ACROSS OUR REGION...RESULTING IN A 
LIKELIHOOD OF SEVERAL SHORTWAVES EJECTING EASTWARD ACROSS THE 
ROCKIES AND GIVING US A CHANCE FOR SEVERAL ROUNDS OF PRECIPITATION 
FROM SUNDAY THROUGH WEDNESDAY NEXT WEEK. THERE IS SOMEWHAT BETTER 
MODEL CONSENSUS THAT THE FIRST SUCH WAVE WILL AFFECT OUR AREA 
SOMETIME LATE SUNDAY/EARLY MONDAY...WITH THE POTENTIAL FOR THE 
CUTOFF LOW TO BECOME CAUGHT UP IN THE NORTHERN STREAM THEREAFTER AND 
THE RESULTING LONGWAVE TROUGH CROSSING OUR REGION AROUND TUESDAY OR 
TUESDAY NIGHT. WHILE IT APPEARS THAT TEMPERATURE PROFILES WILL 
SUPPORT PRIMARILY OR EXCLUSIVELY SNOW WITH EITHER OF THESE 
SYSTEMS...THERE REMAINS MUCH UNCERTAINTY WITH THE EVOLUTION OF THIS 
SCENARIO IN TERMS OF HOW THE STREAMS WILL PHASE...WHAT THE TIMING 
AND LOCATION OF THE TROUGHS WILL BE...AND SO FORTH. WILL THUS 
CONTINUE TO CARRY SLIGHT CHANCES FOR SNOW THROUGH MOST OF THE SUNDAY 
TO WEDNESDAY TIMEFRAME AND AWAIT A CLEARER SOLUTION.

&&

.AVIATION...
03/06Z...UPPER LOW CONTINUES TO DROP SOUTH. AREA OF CLEARING EVIDENT 
FROM CENTRAL THROUGH WESTERN IOWA NOW.  SOME LIGHT SNOW SHOWERS AND 
LOWER CIGS EXPECTED TO ACCOMPANY THE COLDEST AIR ON THURSDAY WITH 
NORTHERN AREAS SEEING MVFR AND POSSIBLY A BRIEF PERIOD OF IFR. 
MEANWHILE TNT...BKN TO OVERCAST VFR TO MVFR CONDITIONS EXPECTED TO 
REMAIN OVER THE REGION...SOME CLEARING IN THE WEST WILL GRADUALLY 
FILL IN AFT 10Z.  HAVE LOOKED AT CIGS FOR MORNING AND BROUGHT UP ONE 
CAT IN SOME CASES. UPSTREAM CIGS HAVE LIFTED WITH DAYTIME...AND 
SOUNDINGS AND GUIDANCE CURRENTLY DONT LOOK THAT LOW. SNOW SHOWERS OR 
FLURRIES FOR THURSDAY WITH MOST LIKELY PERIOD FROM 15Z THROUGH 22Z. 
OUTSIDE OF FAR SOUTH AT KOTM...MOST AREAS WILL SEE SOME SCT -SHSN. 
/REV 

&&

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

&&

$$

SHORT TERM...FAB
AVIATION...REV
LONG TERM...LEE