FXUS64 KFWD 231136
AFDFWD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
536 AM CST WED DEC 23 2009
.AVIATION...
A DIFFICULT TAF FORECAST. CIGS HAVE RISEN TO VFR OVER MUCH OF THE
AREA AND GUIDANCE SEEMS TOO PESSIMISTIC BASED ON LATEST TRENDS.
WILL KEEP MVFR PREVAILING THROUGH THE MORNING AS LOW LEVEL
MOISTURE IS IN PLACE AND CIGS ARE LOWERING AGAIN TO THE SOUTH OF
THE METROPLEX. BELIEVE CIGS WILL LIFT TO VFR WITH HEATING/SWLY
BOUNDARY LAYER FLOW BY EARLY AFTERNOON. VFR SHOULD PREVAIL FROM
MID AFTERNOON INTO THE EVENING HOURS. ASIDE FROM SOME -RA AT DAL
THIS MORNING...BELIEVE ANY CHANCES OF RAIN/CONVECTION TODAY WILL
BE JUST EAST OF TAF SITES. HOWEVER...WILL SHOW VCTS THIS EVENING
AS MAIN UPPER LOW APPROACHES AND PUSHES DRY LINE/PAC FRONT THROUGH
AROUND MIDNIGHT. NAM/WRF SUGGEST SOME POTENTIAL FOR STORMS ALONG
THIS WIND SHIFT...BUT BULK OF THE STORMS WILL BE EAST OF TAF SITES
AGAIN. THERE WILL BE SOME PERIODS OF RAIN BEHIND THE FRONT AFTER
MIDNIGHT IN RESPONSE TO ISENTROPIC/ELEVATED LIFT AHEAD OF THE
UPPER LOW. MVFR CIGS/VSBY WITH RA SHOULD PREVAIL THROUGH SUNRISE.
OTHERWISE...SOUTH WINDS NEAR 12KT EXPECTED TODAY...WITH A SLIGHT
VEERING TO SSW THIS EVENING...AND SHIFTING TO WNW AROUND MIDNIGHT.
WNW WINDS WILL BECOME 20G30KT BY THURS MORNING.
TR.92
&&
.PREV DISCUSSION... /ISSUED 353 AM CST WED DEC 23 2009/
SHOWERS AND THUNDERSTORMS CONTINUE TO OCCUR ACROSS THE EASTERN
HALF OF NORTH TEXAS TONIGHT AS THE FIRST OF SEVERAL SHORTWAVES
MOVES THROUGH THE REGION. A PROMINENT DRY SLOT ON WATER VAPOR IS
EVIDENT MOVING ACROSS THE WESTERN HALF OF NORTH TEXAS WHERE NO
PRECIPITATION HAS BEEN OBSERVED TONIGHT. EXPECT MOST OF THE
SHOWERS AND THUNDERSTORMS TODAY TO REMAIN EAST OF INTERSTATE 35
AND HAVE ADJUSTED POPS ACCORDINGLY. THIS IS THE AREA WHERE HIGHEST
PWATS AND STRONGEST ISENTROPIC LIFT WILL OCCUR. THERE IS STILL A
SLIGHT RISK FOR SEVERE STORMS EAST OF INTERSTATE 35 THIS AFTERNOON
AND EVENING AS WELL. AN ISOLATED SEVERE STORM BEFORE THEN CANNOT
RULED OUT...BUT THE LATE AFTERNOON AND EVENING HOURS LOOK THE MOST
FAVORABLE.
AS THE UPPER LEVEL LOW APPROACHES THIS EVENING AND TONIGHT AND THE
COLD FRONT BEGINS TO ENTER OUR NORTHWESTERN COUNTIES...SHOWERS AND
THUNDERSTORMS WILL LIKELY BECOME NUMEROUS AND THE THREAT FOR
SEVERE WEATHER WILL CONTINUE EAST OF INTERSTATE 35. WILL CARRY
HIGHEST POPS TONIGHT FOR ALL OF THE REGION. THE RAIN WILL LIKELY
END FROM THE SOUTHWEST AS ANOTHER DRY SLOT WORKS IN BEHIND THE
UPPER LEVEL LOW. THE LATEST MODEL RUNS HAVE TRENDED FARTHER SOUTH
WITH THE TRACK OF THE UPPER LEVEL LOW...NOW MOVING IT ACROSS NORTH
TEXAS. THIS WILL ALLOW COLD AIR IN THE LOWER AND MID LEVELS OF THE
ATMOSPHERE TO PENETRATE INTO THE NORTHWESTERN CORNER OF NORTH
TEXAS. AS WRAP AROUND PRECIP MOVES INTO THE NORTHWESTERN COUNTIES
ON THURSDAY MORNING...RAIN MIXED WITH SNOW IS POSSIBLE AND HAVE
INCLUDED THIS IN THE FORECAST FOR LOCATIONS WEST OF A LINE FROM
EASTLAND TO SHERMAN. SURFACE TEMPERATURES ARE STILL FORECAST TO BE
ABOVE FREEZING AT THE TIME...BUT IF THE IMMEDIATE NEAR SURFACE
LAYER COOLS JUST A FEW MORE DEGREES...A CHANGE OVER TO ALL SNOW IS
POSSIBLE. AM NOT EXPECTING IMPACTS AT THIS TIME...HOWEVER IF A
CHANGE OVER TO ALL SNOW OCCURS...SOME LIGHT ACCUMULATIONS ARE
POSSIBLE. WILL NEED TO CONTINUE TO MONITOR THE TRACK OF THE UPPER
LEVEL LOW IN FUTURE MODEL RUNS TODAY.
BEHIND THE COLD FRONT THAT BLOWS THROUGH WEDNESDAY NIGHT...WINDY
CONDITIONS ARE EXPECTED AS THE STORM SYSTEM BECOMES VERTICALLY
STACKED TO OUR NORTHEAST. A WIND ADVISORY WILL LIKELY BE NEEDED
FOR THURSDAY. HAVE CONTINUED TO UNDERCUT MOS A FEW DEGREES FOR
THURSDAY THROUGH FRIDAY.
QUIET AND COOL WEATHER IS EXPECTED THROUGH THE WEEKEND WITH
ANOTHER STORM SYSTEM POSSIBLE BY WEDNESDAY. THE GFS AND ECMWF ARE
NEARLY 48 HOURS APART ON THE TIMING OF THIS NEXT UPPER LEVEL SYSTEM
AND HAVE SIDED WITH THE FASTER ECMWF /WHICH THE GFS ENSEMBLES ALSO
AGREE WITH/ FOR THIS FORECAST. GIVEN THE DISCREPANCIES IN THE
MODELS...WILL CARRY LOW POPS MONDAY NIGHT THROUGH WEDNESDAY UNTIL
A BETTER CONSENSUS OCCURS. WITH COLD AIR ALREADY IN PLACE...THIS
NEXT SYSTEM HAS THE POTENTIAL TO BE A WINTER WEATHER EVENT BUT
WILL NOT MENTION THIS IN THE ZONES.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 71 41 44 25 43 / 40 80 30 5 5
WACO, TX 73 44 50 26 47 / 40 80 20 5 5
PARIS, TX 67 43 45 23 38 / 80 90 50 5 5
DENTON, TX 68 38 41 22 41 / 40 90 40 5 5
MCKINNEY, TX 68 38 44 22 41 / 70 90 50 5 5
DALLAS, TX 71 41 45 25 42 / 50 90 30 5 5
TERRELL, TX 70 46 46 26 43 / 70 90 40 5 5
CORSICANA, TX 72 47 50 27 44 / 60 80 30 5 5
TEMPLE, TX 72 47 51 28 47 / 40 70 10 5 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
92/82
