FXUS63 KOAX 092103
AFDOAX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
303 PM CST WED DEC 9 2009

.SHORT TERM...TONIGHT THROUGH SATURDAY.
COLD TEMPERATURES/WIND CHILLS TONIGHT...THEN TRYING TO WARM
TEMPERATURES INTO THE WEEKEND...ARE THE PRIMARY FORECAST CONCERNS.

TIGHTEST PRESSURE GRADIENT HAS PUSHED EAST OF THE MISSOURI RIVER
THIS AFTERNOON...HOWEVER STILL SEEING WINDS GUSTING TO 30 MPH
ACROSS ALL OF THE CWA. BLOWING SNOW HAS DECREASED MARKEDLY...SO
WILL REMOVE WINTER WEATHER ADVISORY FOR THIS AFTERNOON. HIGH
PRESSURE RIDGE SLIDING SOUTHEAST THROUGH WESTERN NEBRASKA WILL
SETTLE OVER KANSAS THIS EVENING AS WEAK LOW PRESSURE TROUGH DRIFTS
THROUGH THE NORTHERN PLAINS. SO SHOULD MAINTAIN SOME WESTERLY WIND
COMPONENT OVERNIGHT...ON THE ORDER OF 8 TO 12 MPH. THIS SHOULD
HELP KEEP TEMPERATURES FROM BOTTOMING OUT...BUT WILL MAKE WIND
CHILLS COLDER. HAVE LOWS GENERALLY 5 TO 10 BELOW AS UPSTREAM
TEMPERATURES ARE ALREADY BELOW ZERO...AND COMBINED WITH THE
WINDS...WILL SEE WIND CHILL TEMPS AT OR BELOW 20 BELOW ACROSS MUCH
OF THE CWA. THE SOUTHERN CWA MAY HOLD IN THE 15 TO 20 BELOW
RANGE...BUT ADJACENT OFFICES IN KANSAS AND MISSOURI ARE POSTING
WIND CHILL ADVISORIES WHERE CRITERIA ARE A LITTLE HIGHER...SO WILL
FILL IN THE GAP THERE.

LOW LEVEL PATTERN SUGGESTS AN ATTEMPT AT WARMING OVER THE NEXT
COUPLE OF DAYS AS SOUTHWEST TO SOUTH LOW LEVEL FLOW REIGNS ACROSS
THE REGION. HOWEVER DEEP SNOW COVER WILL HOLD TEMPS BELOW MOS
TEMPERATURE GUIDANCE AT LEAST THROUGH FRIDAY. DESPITE PLENTY OF
SUNSHINE THURSDAY...COLD START AND SNOW COVER SHOULD KEEP HIGHS IN
THE TEENS AT BEST. LIGHTER WINDS THURSDAY NIGHT MAY ALLOW EVEN
COLDER TEMPS THAN TONIGHT...BUT HAVE GONE ZERO TO 5 BELOW IN MOST
SPOTS THEN. SOUTH WINDS ON FRIDAY COULD PUSH HIGHS TOWARD
20...WITH CONTINUED WARM ADVECTION KEEPING LOWS IN THE 5 TO 15
ABOVE RANGE...AND HIGHS SATURDAY WELL INTO THE 20S.

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY.
LOW LEVEL MOISTURE WILL BE INCREASING AS WE START THE LONG TERM
PERIOD AS A COUPLE OF DAYS OF SOUTH WINDS DRIVE DEW POINTS INTO
THE TEENS OR EVEN LOWER 20S BY SUNDAY. APPROACHING SHORT WAVE
TROUGH SHOWN BY ECMWF/GFS INDUCES LOW PRESSURE ACROSS KANSAS
SUNDAY...WITH WARM ADVECTION LIFT NOTED ACROSS MUCH OF THE CWA BY
THE AFTERNOON. FORECAST SOUNDINGS SHOW SHALLOW LAYER OF SATURATION
WITH DRY AIR JUST ABOVE...SUGGESTING FREEZING DRIZZLE IS POSSIBLE.
SOME SATURATION IN THE MID LEVELS COULD BRING LIGHT SNOW OR A MIX
AS WELL. WILL MAINTAIN LOW POPS SUNDAY AFTERNOON INTO SUNDAY NIGHT
BEFORE WAVE LIFTS INTO THE GREAT LAKES.

COLD AIR WILL BEGIN TO DROP INTO THE REGION AGAIN BEHIND THIS
SYSTEM...BUT MODELS DIFFER ON DEGREE OF COOLING. GFS WOULD SUGGEST
SIGNIFICANT COOLING ON TUESDAY AS UPPER TROUGH SHARPENS OVER THE
PLAINS AND GREAT LAKES...AND ECMWF MAINTAINS SOMEWHAT FLATTER FLOW
KEEPING COLD AIR BOTTLED UP WELL NORTH OF THE AREA. IN FACT...12Z
GFS FORECAST SOUNDINGS SHOW TEMPERATURES PLUMMETING INTO THE
SINGLE DIGITS BY NOON TUESDAY. WITH SIGNIFICANT DIFFERENCES IN
MODELS...WILL MAINTAIN A RATHER COOL FORECAST WITH ONLY SMALL
PRECIP CHANCES UNTIL PATTERN CAN BE DISCERNED.

DERGAN

&&

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

18Z TAFS

NW WINDS WILL GRADUALLY DIMINISH TO LESS THAN 10KT BY 10/00Z ALL TAF 
SITES. OTHERWISE VFR CONDITIONS WILL PREVAIL THRU THE FCST PD AS SFC 
HIGH PRESSURE DOMINATES OVER THE CENTRAL PLAINS. 

DEE

&&

.OAX WATCHES/WARNINGS/ADVISORIES...
NE...WIND CHILL ADVISORY FROM 9 PM THIS EVENING TO 10 AM CST THURSDAY 
     FOR NEZ011-012-015>018-030>034-042>045-050>053-065>068-078-
     088>093.

IA...WIND CHILL ADVISORY FROM 9 PM THIS EVENING TO 10 AM CST
     THURSDAY FOR IAZ043-055-056-069-079-080-090-091.

&&

$$