FXUS63 KDMX 031129
AFDDMX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
530 AM CST THU DEC 3 2009

.SHORT TERM [TODAY]...
VORT MAX ROTATING AROUND UPPER LOW IN PLACE ACROSS THE NORTHERN 
PLAINS TO BE THE MAIN FOCUS FOR TODAY. LIFT ASSOCIATED WITH THIS 
WAVE TO INCREASE ACROSS THE NORTHERN CWA BY THIS MORNING...SPREADING 
ACROSS MUCH OF THE REMAINDER OF THE CWA THIS AFTERNOON. DEEPEST 
MOISTURE SITUATED ACROSS THE NORTHERN CWA...WITH TEMPERATURES COLD 
ENOUGH THAT ALL PRECIP SHOULD BE IN THE FORM OF SNOW. BEST CHANCES 
TO SEE SOME LIGHT SNOW SHOWERS WILL BE NORTH OF HIGHWAY 20...WITH AN 
ISOLATED OR SCATTERED SHOWER POSSIBLE I-80 TO HWY 20...AND FLURRIES 
EXPECTED FURTHER SOUTH. ONLY A FEW HUNDREDTHS OF MOISTURE 
AVAILABLE...WITH SNOW RATIOS EXPECTED TO REMAIN AROUND 12 TO 15 TO 
1. LAPSE RATES QUITE STEEP SO DO EXPECT MORE OF A SNOW SHOWER TYPE 
EVENT THAN STRATIFORM SNOWFALL. THUS EXPECT ABOUT A HALF AN INCH TO 
AN INCH ACROSS MOST AREAS...WITH A FEW PLACES THAT COULD SEE 1 TO 2 
INCHES OF SNOW POSSIBLE THROUGH THIS AFTERNOON. WITH CLOUDS EXPECTED 
ACROSS MUCH OF THE AREA TODAY...AND SNOW SHOWERS ANTICIPATE LITTLE 
WARMING EVEN WITH THE WEAK WAA ALOFT. THEREFORE HAVE AROUND A 5 TO 7 
DEGREE DIURNAL RANGE.

.LONG TERM [TONIGHT THROUGH WEDNESDAY]...
POTENTIAL FOR SNOW WILL CONTINUE THROUGH EARLY THIS EVENING...MAINLY 
OVER THE NORTHEAST WHERE MINOR ADDITIONAL ACCUMULATIONS MAY OCCUR. 
FLURRIES WILL REMAIN POSSIBLE ELSEWHERE. MID LEVEL DRYING WILL OCCUR 
FROM WEST TO EAST THROUGHOUT THE EVENING AS THE FLOW BECOMES MORE 
WESTERLY TO BRING AN END TO THE PRECIPITATION. DESPITE THE WESTERLY 
FLOW CONTINUING ON FRIDAY...HIGH TEMPERATURES WILL REMAIN QUITE 
COOL. MIXING WILL REACH UP TO 850 MB HOWEVER WITH TEMPERATURES AT 
THAT LEVEL OF -14C TO -16C WILL RESULT IN HIGHS IN THE LOWER 20S 
NORTH TO THE MID TO UPPER 20S SOUTH. A LITTLE WARMER ON SATURDAY 
WITH HIGHS IN THE 30S. 

THE NEXT SYSTEM TO AFFECT THE STATE WILL ARRIVE LATE SUNDAY AND 
SUNDAY NIGHT. A STRONG SHORT WAVE CURRENTLY OFF THE WEST COAST OF 
THE PACIFIC NORTHWEST NEAR THE GULF OF ALASKA...WILL DIVE SOUTHEAST 
THROUGH THE INTERMOUNTAIN WEST FRIDAY NIGHT AND SATURDAY. A PORTION 
OF THIS ENERGY WILL BE EJECTED OUT TOWARDS THE MIDWEST SATURDAY 
NIGHT. CONFIDENCE IS INCREASING FOR THE POTENTIAL OF ACCUMULATING 
SNOW TO BEGIN OVER WESTERN IOWA LATE SUNDAY AND SPREAD ACROSS THE 
REMAINDER OF THE AREA SUNDAY NIGHT. ADVISORY CRITERIA TYPE SNOWFALLS 
CAN NOT BE RULED OUT WITH THIS SYSTEM. THE SYSTEM WILL QUICKLY MOVE 
OUT BY MONDAY. THE REMAINDER OF THE WESTERN ENERGY IS EXPECTED TO 
CROSS THE ROCKIES SOMETIME TUESDAY. THIS SYSTEM LOOKS MORE POTENT 
THOUGH ITS TRACK REMAINS UNCERTAIN. A MORE NORTHERLY TRACK WOULD 
MAKE IT INTERESTING IN IOWA. ANOTHER ROUND OF COLD AIR WILL BE 
PULLED DOWN BEHIND THIS SYSTEM. A LITTLE SNOW COVER WOULD MAKE A BIG 
DIFFERENCE AS TO HOW COLD THIS INTRUSION WILL BE.

&&

.AVIATION...
03/12Z...SOME LIGHT SNOW SHOWERS ALREADY MOVING ACROSS THE 
NORTHEASTERN CWA EXPECTED TO IMPACT KMCW AND KALO THROUGHOUT THE 
FIRST FEW HOURS OF THE TAF PERIOD. UPPER LOW DROPPING SOUTHEAST 
THROUGH THE AREA TODAY...EXPECTED TO SPREAD LIGHT SNOW SHOWERS FROM 
NORTHWEST TO SOUTHEAST THROUGHOUT THE DAY TODAY. CIGS EXPECTED TO 
REMAIN IN THE MVFR TO VFR RANGE...BUT MAY OCCASIONALLY DIP INTO IFR 
CONDITIONS. VSBYS SHOULD REMAIN IN THE MVFR TO VFR RANGE IN THE 
SNOW. NORTHWEST WINDS WILL PICK UP DURING THE DAY...AND THEN 
EXPECTED TO DROP TO AROUND 10KTS AGAIN TONIGHT. 

&&

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

&&

$$

SHORT TERM...BEERENDS
AVIATION...BEERENDS
LONG TERM...DONAVON