FXUS63 KOAX 300945
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
345 AM CST MON NOV 30 2009

.DISCUSSION...
TEMPERATURES ARE THE MAIN CONCERN FOR MOST OF THE WEEK.  

ECMWF...GFS...AND NAM ARE IN AGREEMENT WITH THE MAJOR UPPER TROUGH 
THAT WILL AFFECT THE WEATHER STARTING TUESDAY THROUGH THE REMAINDER 
OF THE WEEK.  THIS TROUGH IS STILL OFFSHORE OF THE PACIFIC 
NORTHWEST. THE GFS AND ECMWF HANDLE THIS SYSTEM SIMILARLY THROUGH 
THURSDAY...WITH THE GFS BEING A BIT DEEPER AND FASTER. FROM NOW 
UNTIL TUESDAY...THE UPPER AIR PATTERN WILL BE ZONAL WITH SOME SLIGHT 
RIDGING.  THIS WILL ALLOW TEMPERATURES TO WARM TO THE LOWER TO MID 
50S ON MONDAY AND TUESDAY.   

UPPER TROUGH AND ASSOCIATED COLD FRONT MOVES ACROSS THE AREA ON 
WEDNESDAY. COLD FRONT IS PROGGED TO COME THROUGH THE AREA DRY.  BUT 
THIS WILL START A SIGNIFICANT COOL DOWN THAT REMAINS IN PLACE 
THROUGH THE DAY 7 PERIOD. A SECONDARY SHOT OF ARCTIC AIR IS FORECAST 
TO COME IN ON WEDNESDAY NIGHT INTO THURSDAY.  AS THIS SECOND SHOT OF 
COLD AIR COMES DOWN...BOTH THE ECMWF AND GFS INDICATE SOME MOISTURE 
AND TEMPERATURES AT 850 MB NEAR THE RANGE OF DENDRITIC CRYSTAL 
FORMATION. THUS...SOME SNOW FLURRIES ARE POSSIBLE...ESPECIALLY IN 
THE VICINITY OF THE MISSOURI RIVER VALLEY EASTWARD. TEMPERATURES ON 
WEDNESDAY IN THE MID 30S...AND COLDER ON THURSDAY ...WITH HIGHS 
AROUND 30.

BY FRIDAY...BOTH THE GFS AND ECMWF DIVERGE IN THEIR SOLUTIONS FOR 
THE WEEKEND.  THE ECMWF KEEPS THE LARGE UPPER TROUGH ENTRENCHED FROM 
JAMES BAY SOUTH TO THE GREAT LAKES...WITH REINFORCING NORTHERN 
STREAM ENERGY DIVING SOUTHWARD INTO THE PLAINS.  THE GFS IS MORE 
PROGRESSIVE WITH THE MOVEMENT OF THE LARGE UPPER TROUGH AND HAS IT 
EAST OF THE UPPER GREAT LAKES...WITH SOME RIDGING OVER THE PLAINS.  
THE GFS ALSO BRINGS A SIGNIFICANT SHORTWAVE TROUGH EASTWARD ACROSS  
THE NORTHERN PLAINS INTO THE UPPER GREAT LAKES WITH IOWA AND 
NEBRASKA IN ZONAL FLOW.  THUS...THE GFS SOLUTION IS MORE MODERATE IN 
TEMPERATURES THAN THE COLDER ECMWF. AT THIS TIME...TEMPERATURES ARE 
SOMEWHAT BETWEEN BOTH MODEL SOLUTIONS...IN THE MID TO UPPER 30S FOR 
HIGHS. HOWEVER...THIS TEMPERATURE FORECAST HAS LOW CONFIDENCE. IF 
THE ECMWF IS RIGHT...TEMPERATURES COULD BE MUCH COLDER.    

SMITH

&&

.AVIATION...
TAF SITES KOFK/KOMA/KLNK 

30/06Z TAFS

VFR CONDITIONS ARE EXPECTED THROUGH TUESDAY MORNING. ONLY PASSING 
HIGH CLOUDS ARE EXPECTED FROM TIME TO TIME WITH WEST OR SOUTHWEST 
WINDS AT OR BELOW 12KTS.

DERGAN

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
IA...NONE.
&&

$$