FXUS64 KOUN 282040
AFDOUN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
240 PM CST SAT NOV 28 2009

.DISCUSSION...
THE NAM EXHIBITS GOOD RUN-TO-RUN CONSISTENCY WITH ITS TIMING 
OF THE COLD FRONT FOR TONIGHT AND EARLY SUNDAY AND THE PROGRESSION 
OF THE CUTOFF LOW ACROSS NORTHERN MEXICO THROUGH EARLY TUESDAY.
THE COLD FRONT SHOULD MOVE INTO NORTHWEST OKLAHOMA THIS EVENING
AND EXIT THE SOUTHEAST PART OF THE CWA SUNDAY MORNING. ALTHOUGH
HIGH TEMPERATURES WILL FALL NEARLY 20 DEGREES OVER A GOOD PART OF
THE AREA ON SUNDAY... THEY WILL STILL ONLY BE SLIGHTLY BELOW
NORMAL AS THE AIRMASS IS PRIMARILY PACIFIC IN ORIGIN. 

MID-LEVEL WEAK ISENTROPIC LIFT ON SUNDAY COMBINED WITH AN INCREASE IN
HUMIDITIES AT THAT LEVEL... ALONG WITH SURFACE COLD FRONT MOVING
THROUGH THE AREA... SHOULD PROVIDE ENOUGH SUPPORT FOR SCATTERED
SHOWERS. HOWEVER... WE WILL SHIFT THE HIGHEST POPS INTO THE
AFTERNOON HOURS AS THE MID-LEVEL MOISTURE WILL STILL BE SOMEWHAT
LACKING DURING THE MORNING. RAINFALL AMOUNTS ARE EXPECTED TO BE
RELATIVELY LIGHT. BY SUNDAY AFTERNOON... THE 850 TO 700 MB
THICKNESSES ALONG WITH LOW-LEVEL WET BULB TEMPERATURES NEAR FREEZING
SUGGEST A SLIM POSSIBILITY OF A MIX OF LIGHT RAIN/SNOW ACROSS
NORTHWEST OKLAHOMA. HOWEVER... THE BOUNDARY LAYER TEMPERATURES ARE
FORECAST TO REMAIN RELATIVELY WARM... AND WITH ONLY LIGHT PCPN
EXPECTED... DOUBT THERE WILL BE SUFFICIENT EVAPORATIVE COOLING TO
LOWER THE SURFACE WET BULB TEMPERATURES TO FREEZING.

IN THE LATER FORECAST PERIODS... THE NAM CONTINUES TO BE A LITTLE
SLOWER AND FARTHER SOUTH WITH THE POSITION OF THE UPPER LOW TUESDAY
COMPARED TO THE GFS AND ECMWF. ATTM... WILL TREND TOWARDS THE GFS
AND SPREAD POPS A LITTLE FARTHER NORTH INTO CENTRAL OKLAHOMA FOR
TUESDAY NIGHT BUT WILL STAY LOWER THAN THE MORE BULLISH ECMWF.

IN THE 7 TO 9 DAY PERIODS... THE 12Z RUN OF THE GFS IS
SIGNIFICANTLY COLDER THAN THE PRIOR COUPLE OF RUNS AS IT PLUNGES
CANADIAN AIR SOUTHWARD THROUGH THE PLAINS. SINCE MOST OF THE
CHANGE OCCURS JUST BEYOND THE CURRENT FORECAST PERIOD THERE WILL
BE A COUPLE MORE MODEL RUNS TO EXAMINE BEFORE IT MOVES VERY FAR
INTO THE FORECAST PERIOD.

&&

.PRELIMINARY POINT TEMPS/POPS...
OKLAHOMA CITY OK  46  50  34  58 /   0  40  20   0 
HOBART OK         42  48  31  53 /   0  30  10   0 
WICHITA FALLS TX  51  54  35  57 /  10  40  20  10 
GAGE OK           37  46  24  56 /   0  30   0   0 
PONCA CITY OK     43  50  30  57 /   0  30  10   0 
DURANT OK         56  57  42  58 /  10  50  40  10 

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...NONE.
TX...NONE.
&&

$$

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