[MCD] SWOMCD

Sat Jan 13 12:26:14 UTC 2007

ACUS11 KWNS 131229
SWOMCD
SPC MCD 131228 
ARZ000-OKZ000-TXZ000-131630-

MESOSCALE DISCUSSION 0048
NWS STORM PREDICTION CENTER NORMAN OK
0628 AM CST SAT JAN 13 2007

AREAS AFFECTED...NRN TX...SE OK AND NW AR

CONCERNING...FREEZING RAIN 

VALID 131228Z - 131630Z

SCATTERED SHOWERS OF FREEZING RAIN AND SLEET ARE CURRENTLY ONGOING
FROM NORTH TX EXTENDING NEWD THROUGH SE OK INTO NW AR. THE COVERAGE
OF FREEZING RAIN AND SLEET MAY INCREASE THIS MORNING WITH
PRECIPITATION AMOUNTS THROUGH EARLY AFTERNOON GENERALLY RANGING FROM
.2 TO .5 INCHES ACROSS THE MCD AREA.

LATEST SFC ANALYSIS SHOWS A COLD FRONT LOCATED FROM LITTLE ROCK AR
EXTENDING SWWD TO EAST TX AND WWD INTO THE TX HILL COUNTRY. THE
FREEZING LINE IS LOCATED ABOUT 120 MILES NORTHWEST OF THE FRONT.
SUBFREEZING TEMPS EXIST FROM JUST WEST AND NORTH OF THE DALLAS FORT
WORTH METROPLEX NNEWD ACROSS MOST OF ERN OK TO NORTH OF FORT SMITH
AR. THE FREEZING LINE SHOULD SLOWLY MOVE SWD THIS MORNING.

AT THE SAME TIME...A SUBTROPICAL FEED OF LOW TO MID-LEVEL MOISTURE
WILL REMAIN IN PLACE EXTENDING NEWD FROM WEST TX ACROSS NORTH TX
INTO ERN OK. ALTHOUGH SUBTLE...THE LATEST WATER VAPOR IMAGERY SHOWS
A LOW-AMPLITUDE SHORTWAVE ACROSS WEST TX WHICH SHOULD INCREASE
LARGE-SCALE ASCENT ACROSS NORTH TX AND SRN OK OVER THE NEXT FEW
HOURS AS THE FEATURE MOVES NEWD. IN ADDITION...A 40 TO 50 KT
LOW-LEVEL JET IN EAST TX...SE OK AND WRN AR WILL RESULT IN STRONG
ISENTROPIC LIFT NORTH OF THE BOUNDARY. THE INCREASING PVA ASSOCIATED
WITH THE APPROACHING WAVE COUPLED WITH STRONG ASCENT DUE TO THE
LOW-LEVEL JET SHOULD RESULT IN AN INCREASE IN PRECIPITATION COVERAGE
THIS MORNING ALONG A CORRIDOR FROM FORT WORTH TX NEWD TO NEAR FORT
SMITH AR. MODEL FORECASTS CONFIRM THIS WITH QPF AMOUNTS RANGING FROM
.25 TO 1.00 INCHES ACROSS THE SERN HALF OF THE MCD AREA THROUGH
MIDDAY. ALTHOUGH MODEL FORECASTS MAY BE A LITTLE HIGH IN THE QPF
AMOUNTS...SUBFREEZING TEMPS ACROSS THE MCD AREA SHOULD RESULT IN
SIGNIFICANT ICE ACCUMULATION THROUGH EARLY AFTERNOON.

FORECAST SOUNDINGS AND 12Z OBSERVED SOUNDINGS FROM OUN AND FTW
CONFIRM A WARM LAYER EXISTING 1500 TO 2000 FEET ABOVE THE GROUND
WITH TEMPS AS WARM AS +10 TO +13 C. THIS SHOULD RESULT IN FREEZING
RAIN AS THE DOMINANT MODE OF PRECIPITATION ALTHOUGH SLEET WILL ALSO
BE POSSIBLE ESPECIALLY IN THE NWRN PART OF THE MCD AREA WHERE TEMPS
IN THE WARM LAYER WILL BE A LITTLE COOLER.

..BROYLES.. 01/13/2007

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

...NOTICE...
SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A
SCHEDULED BASIS FROM DECEMBER 1 THROUGH FEBRUARY 28...FOUR
TIMES A DAY...AROUND 00 UTC...06 UTC...12 UTC...AND 18 UTC
FOR SIGNIFICANT SHORT RANGE WINTER WEATHER EVENTS.

ATTN...WFO...LZK...SHV...TSA...FWD...OUN...

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