SWOMCD
SPC MCD 241723
OKZ000-KSZ000-TXZ000-242330-
MESOSCALE DISCUSSION 2284
NWS STORM PREDICTION CENTER NORMAN OK
1123 AM CST THU DEC 24 2009
AREAS AFFECTED...N-CENTRAL AND NERN TX...ERN OK...SERN KS
CONCERNING...WINTER MIXED PRECIPITATION
VALID 241723Z - 242330Z
BRIEF FREEZING RAIN TRANSITIONING TO SLEET IS EXPECTED DURING THE
EARLY TO MID AFTERNOON TIME FRAME...BEFORE CHANGING OVER TO SNOW
DURING THE 21-00Z PERIOD ACROSS N-CENTRAL/NERN TX NWD THROUGH ERN OK
AND SERN KS. STRONG/GUSTY NWLY WINDS WILL ACCOMPANY THE TRANSITION
TO SNOW...POTENTIALLY RESULTING IN VISIBILITY REDUCTION TO A QUARTER
OF A MILE.
CLOSED MID LEVEL LOW OBSERVED OVER NRN/WRN TX IN 12Z UPPER AIR DATA
IS FORECAST TO BEGIN LIFTING NEWD TOWARD THE ARKLATEX REGION IN
RESPONSE TO A SECOND DISTURBANCE DROPPING S THROUGH THE NRN HIGH
PLAINS. AS A RESULT...LOW LEVEL CYCLONE WILL DEVELOP NWD ACROSS
AR...WHICH WILL ALLOW SUBFREEZING AIRMASS LOCATED OVER THE
CENTRAL/SRN HIGH PLAINS TO ADVANCE EWD INTO N-CENTRAL/NERN TX...ERN
OK...AND SERN KS. PRONOUNCED MID LEVEL DRY SLOT OBSERVED IN MORNING
SATELLITE IMAGERY IS ADVANCING NWD ACROSS ERN TX AND TOWARD ERN
OK/WRN AR...WITH STRONG ASCENT /AND REDUCTION IN STABILITY NW OF THE
DRY SLOT PER RECENT LIGHTNING STRIKES ALONG THE RED RIVER/ OCCURRING
WITHIN TROWAL LIKE FEATURE N AND W OF THE MID LEVEL LOW.
PRECIPITATION MAY DECREASE FOR A SHORT PERIOD OF TIME BENEATH THE
DRY SLOT OVER NERN TX/ERN OK...BUT IS FORECAST TO REINTENSIFY BY 21Z
AS THE TROWAL OVERSPREADS THE REGION. AS THIS OCCURS...A MIXTURE OF
FREEZING RAIN AND SLEET WILL BE POSSIBLE DURING THE 18-21Z
PERIOD...BEFORE TEMPERATURES THROUGHOUT THE BOUNDARY LAYER BEGIN TO
FALL BELOW FREEZING DURING THE 21-00Z PERIOD. BY LATE
AFTERNOON/EARLY EVENING...SNOWFALL RATES MAY APPROACH 1 IN/HR INVOF
THE RED RIVER NWD ACROSS CENTRAL/E-CENTRAL OK AND TOWARDS THE OK/KS
BORDER.
IN ADDITION...VAD WIND PROFILER DATA ACROSS WRN OK INDICATES VERY
STRONG NLY FLOW WITHIN THE LOWEST 1 KM /AOA 40-50 KT/...WHICH WILL
LIKELY BACK TO NWLY DURING THE AFTERNOON AS THE SURFACE LOW BEGINS
TO LIFT FURTHER N. RESULTANT STRONG GUSTY WINDS AT THE SURFACE
COMBINED WITH THE SNOWFALL WILL POTENTIALLY RESULT IN VISIBILITY
REDUCTIONS TO A QUARTER MILE.
..GARNER.. 12/24/2009
...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...SGF...SHV...EAX...TSA...TOP...ICT...FWD...OUN...
LAT...LON 38399609 38629541 38409469 37009463 35819469 33889505
33209545 32839615 32839685 33199720 33979703 35919652
36659716 37089727 37669693 38399609
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