FXUS64 KFWD 240949
AFDFWD
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FORT WORTH TX
349 AM CST THU DEC 24 2009
.AVIATION...
MVFR CIGS ARE EXPECTED TO PREVAIL THROUGH TODAY AND WINDS WILL
STEADILY INCREASE TO NEAR 25G35KT FROM 300 DEG. THIS MAY RESULT IN
CROSS WIND ISSUES AT TIMES ON NORTH-SOUTH RUNWAYS.
EXPECT BAND OF RAIN ASSOCIATED WITH THE WARM CONVEYOR BELT AHEAD
OF THE POWERFUL UPPER LEVEL LOW TO MOVE INTO METROPLEX BY 5AM/11Z.
THIS BAND OF RAIN WILL PERSIST FOR A FEW HOURS...BUT MAY END BY
MID MORNING AS DRY SLOT WORKS IN. HOWEVER...THE PASSAGE OF THE
UPPER LOW AROUND 16-17Z/10-11AM SHOULD COOL THE COLUMN BELOW
FREEZING...AND EXTENSIVE WRAP AROUND PRECIPITATION IS EXPECTED TO
AFFECT THE METROPLEX BY NOON AND INTO THE AFTERNOON HOURS. SURFACE
TEMPS INITIALLY ABOVE FREEZING SHOULD DROP TO 32 AS FALLING SNOW
FORCES COOLING AT THE SURFACE. ACCUMULATIONS NEAR AN INCH WILL BE
POSSIBLE AT AIRPORTS...ESPECIALLY ON ELEVATED SURFACES. SNOW AND
BLOWING SNOW WILL REDUCE VISIBILITIES TO 1/2SM WITH CIGS FALLING
TO IFR WHEN PRECIPITATION IS HEAVIEST. EXPECT THE WORST CONDITIONS
TO OCCUR FROM AROUND NOON INTO THE MID AFTERNOON HOURS. SNOW
INTENSITY SHOULD WANE AFTER 21Z/3PM AND FINALLY COME TO AN END
AROUND SUNSET...WITH CLEARING SKIES THEREAFTER. WINDS WILL REMAIN
NEAR 20KT OVERNIGHT.
FOR WACO...MVFR CIGS AND RAIN EXPECTED THIS MORNING. SOME SNOW MAY
MIX WITH THE RAIN AROUND NOON...BUT NO IMPACTS ARE EXPECTED FROM
ANY SNOW DUE TO LIGHT INTENSITY. SKC/VFR WITH CONTINUED STRONG
WEST WINDS WILL PREVAIL THIS EVENING.
TR.92
&&
.PREV DISCUSSION... /ISSUED 321 AM CST THU DEC 24 2009/
COLD FRONT IS ABOUT 2/3RDS OF THE WAY THROUGH NORTH TEXAS AND WILL
HAVE MOVED THROUGH ALL OF NORTH TEXAS BY DAYBREAK. TEMPERATURES
ARE DROPPING SIGNIFICANTLY BEHIND THE COLD FRONT AND ALL LOCATIONS
WILL SEE THEIR HIGH TEMPERATURES TODAY EARLY THIS MORNING WITH
TEMPERATURES FALLING THROUGHOUT THE DAY. STRONG NORTHWEST WINDS
WILL CONTINUE TODAY AND THE WIND ADVISORY WILL REMAIN IN EFFECT
THROUGH 03Z/9 PM BUT MAY HAVE TO BE EXTENDED A FEW MORE HOURS.
THE EXCITING AND CHALLENGING PART OF THE FORECAST IS THE LIKELIHOOD
OF SNOW TODAY. THE ONLY SIGNIFICANT CHANGES FROM LAST NIGHT ARE TO
INCREASE THE SNOW TOTAL AMOUNTS AND EXTEND THE WARNING AND
ADVISORY THROUGH 00Z/6 PM. THE UPPER LEVEL LOW IS CURRENTLY NEAR
MIDLAND AND WILL ARRIVE IN NORTH TEXAS MID-LATE MORNING. THE
LATEST MODELS PROGRESS THE UPPER LEVEL LOW RIGHT ALONG THE
INTERSTATE 20 CORRIDOR...SETTING UP A SNOW EVENT FOR THE NORTHERN
HALF OF NORTH TEXAS. SNOW ACCUMULATIONS HAVE BEEN RAISED TO NEARLY
5" IN THE NORTHWEST TAPERING TO 1" IN THE ADVISORY AREA. GIVEN THE
SLOWER SPEED OF THE SYSTEM...HAVE ALSO LINGERED LIGHT SNOW ACROSS
THE NORTHEAST THROUGH MIDNIGHT AS THE SYSTEM EXITS THE REGIONS.
WE CHOSE TO USE A 7:1 SNOW RATIO AND THE AVERAGE OF REASONABLE
SREF MEMBERS FOR SNOW TOTALS.
THE COMBINATION OF SNOW AND STRONG WINDS WILL CAUSE BLOWING SNOW
ACROSS MUCH OF THE WARNING AND ADVISORY AREA...BUT MOST LIKELY IN
THE NORTHWESTERN COUNTIES. THIS WILL RESULT IN REDUCED
VISIBILITIES...DOWN TO A QUARTER MILE AT TIMES IN SOME
LOCATIONS...RESEMBLING BLIZZARD-LIKE CONDITIONS. MINOR SNOW
DRIFTS OF A FEW FEET WILL LIKELY FORM DUE TO THE BLOWING SNOW.
THESE SNOW DRIFTS WILL FORM AGAINST BUILDINGS AND OTHER STANDING
OBJECTS SUCH AS FENCES.
AS THE RUC SUGGESTS...IT IS POSSIBLE THAT WE MAY GET DRY-SLOTTED
OR TOO MUCH WARM AIR NEAR 700 MB MAY GET WRAPPED AROUND THE
SYSTEM. THIS WOULD RESULT IN LOWER SNOW ACCUMULATIONS OR A MIX OF
FREEZING RAIN/SLEET/SNOW MAY OCCUR. HOWEVER...GIVEN THE OVERALL
PERSISTENCE OF THE MODEL RUNS WE WILL CONTINUE WITH SNOW MENTIONED
AS THE MAIN PRECIPITATION TYPE.
BEYOND TODAY...THE FORECAST REMAINS NEARLY UNCHANGED UNTIL
TUESDAY. COOL AND DRY WEATHER WILL PERSIST FRIDAY THROUGH MONDAY.
THE ECMWF AND GFS HAVE COME IN BETTER AGREEMENT REGARDING THE NEXT
STORM SYSTEM ON TUESDAY. HAVE MENTIONED A WINTER PRECIPITATION MIX
OF RAIN AND SLEET IN THE FORECAST FOR TUESDAY DUE TO UNCERTAINTIES
IN THE FORECAST THIS FAR OUT. IT APPEARS MORE LIKELY THAT SNOW IN THE
NORTH AND FREEZING RAIN IN THE SOUTH MAY OCCUR BUT WILL FINE TUNE
AS NEEDED AS THE EVENT APPROACHES. HAVE SIGNIFICANTLY UNDERCUT
MOS TEMPERATURES ON TUESDAY TO COINCIDE WITH THE WINTER WEATHER EVENT.
82/JLD
&&
.PRELIMINARY POINT TEMPS/POPS...
DALLAS-FT. WORTH, TX 40 23 43 27 47 / 90 20 5 5 5
WACO, TX 45 27 47 28 52 / 60 5 5 5 5
PARIS, TX 49 22 39 23 43 / 100 50 5 5 5
DENTON, TX 40 22 41 25 48 / 90 30 5 5 5
MCKINNEY, TX 44 21 41 25 48 / 90 40 5 5 5
DALLAS, TX 43 23 44 27 47 / 90 20 5 5 5
TERRELL, TX 47 25 44 27 50 / 90 30 5 5 5
CORSICANA, TX 48 26 46 29 53 / 70 10 5 5 5
TEMPLE, TX 46 26 49 28 52 / 50 5 5 5 5
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY FROM 9 AM THIS MORNING TO 6 PM CST THIS
EVENING FOR TXZ094-095-104>107-118>123-130>134-141.
WIND ADVISORY UNTIL 9 PM CST THIS EVENING FOR TXZ091>095-100>107-
115>123-129>135-141>148-156>162-174-175.
WINTER STORM WARNING UNTIL 6 PM CST THIS EVENING FOR TXZ091>093-
100>103-115>117-129.
&&
$$
92/82
