[MCD] SWOMCD

Sun Jan 14 07:12:31 UTC 2007

ACUS11 KWNS 140715
SWOMCD
SPC MCD 140715 
OKZ000-TXZ000-141315-

MESOSCALE DISCUSSION 0057
NWS STORM PREDICTION CENTER NORMAN OK
0115 AM CST SUN JAN 14 2007

AREAS AFFECTED...WCENTRAL/NWRN TX AND SWRN OK

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 140715Z - 141315Z

FREEZING DRIZZLE AND POSSIBLY VERY LIGHT FREEZING RAIN IS
ANTICIPATED TO DEVELOP OVER THE AREA IN THE NEXT FEW HOURS.
PRECIPITATION IS EXPECTED TO INCREASE IN INTENSITY AND MIX WITH OR
CHANGEOVER TO SLEET TOWARDS 12Z.

ANALYSES OF SFC WINDS/SLP OVER THE SRN PLAINS INDICATES A CONTINUED
GRADUAL BACKING/FALLING OVER THE LAST FEW HRS IN RESPONSE TO
APPROACHING SHORTWAVE TROUGH LOCATED NEAR THE AZ/NM BORDER. THE 850
MB FLOW ALSO HAS BEEN BACKING AND STRENGTHENING  NOTED BY THE RECENT
VWP DATA FROM MAF/SJT AND DYS. AS A RESULT...ISENTROPIC LIFT HAS
BECOME MORE NORMAL TO THE FRONTAL ZONE ENHANCING LOW LEVEL VERTICAL
MOTION. THIS WILL CONTINUE TO SUPPORT THE DEVELOPMENT OF A LARGE
AREA OF FREEZING DRIZZLE AND POSSIBLY VERY LIGHT FREEZING RAIN
ACROSS WCENTRAL/NWRN TX INTO SWRN OK OVER THE NEXT SEVERAL HOURS.

MID LEVELS ARE BEGINNING TO MOISTEN AS NOTED BY THE 07Z OBS AT EL
PASO AND CLOUD TOP COOLING ON IR SAT IMAGERY. THIS WAS OCCURRING
WHERE A LARGE PLUME OF HIGH LEVEL PACIFIC MOIST PLUME HAS BEGUN TO
INTERACT WITH THE SWRN SHORTWAVE TROUGH. THIS MID LEVEL MOISTURE AND
ASSOCIATED LIFT SHOULD CONTINUE TO SPREAD NEWD AND BEGIN TO REACH
THE MCD AREA AFTER 10Z. EVENTUALLY...THE COLUMN WILL SATURATE
SUFFICIENTLY THAT SLEET AND/OR FREEZING RAIN DEVELOPMENT IS EXPECTED
TOWARDS 12Z. THE PTYPE IS EXPECTED TO BE A MIX OF FREEZING RAIN AND
SLEET WCENTRAL/NWRN TX. SLEET IS EXPECTED TO BE THE PRIMARY PTYPE
OVER SWRN OK WHERE MIN TEMPERATURES IN THE LOWEST 2000 FT AGL ARE
EXPECTED TO BE AROUND -10 DEG C.

..CROSBIE.. 01/14/2007

...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...FWD...OUN...SJT...LUB...AMA...MAF...

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