MESOSCALE DISCUSSION 2558
   NWS STORM PREDICTION CENTER NORMAN OK
   1144 PM CST TUE DEC 21 2004
   
   AREAS AFFECTED...SRN TX PANHANDLE...TX SOUTH PLAINS NEWD INTO SWRN
   OK
   
   CONCERNING...HEAVY SNOW 
   
   VALID 220544Z - 221145Z
   
   HVY SNOW WITH HOURLY ACCUMULATIONS AROUND 1 INCH ARE ANTICIPATED TO
   DEVELOP BETWEEN 06-09Z OVER THE SRN TX PANHANDLE/FAR NWRN TX...AND
   BETWEEN 09-12Z OVER SWRN OK. THE AXIS OF HEAVIEST SNOW IS
   ANTICIPATED TO BE ROUGHLY 20 MILES EITHER SIDE OF A LINE PVW TO CDS
   TO LAW DURING THIS PERIOD.
   
   RADAR RETURNS FROM KAMA INDICATES LOW-MID LEVEL SATURATION WAS
   OCCURRING FAIRLY QUICKLY AS MID LVL LOW ROTATES OUT OF NM. THIS
   TREND SHOULD SUPPORT SNOW DEVELOPMENT OVER THE SWRN TX PANHANDLE/NRN
   TX SOUTH PLAINS REGION OVER THE NEXT FEW HOURS. STRONGEST LIFT
   ASSOCIATED WITH DEFORMATION ZONE IN THE 700-600 MB LAYER COINCIDENT
   WITH THERMODYNAMIC PROFILES SUPPORTIVE OF HVY SNOW WILL OVERSPREAD
   THE AREA AS THE MID LEVEL LOW MIGRATES FROM CENTRAL NM INTO THE SERN
   TX PANHANDLE BY 12Z. MID LEVEL FRONTOGENETIC FORCING IS ANTICIPATED
   TO BEGIN AS STRONG MID LEVEL SPEED MAX OVER SRN NM/FAR WRN TX
   ROTATES NEWD INTO NWRN TX. AXIS OF STRONGEST MID LEVEL FRONTOGENETIC
   FORCING SHOULD DEVELOP ROUGHLY ALONG THE MID LEVEL LOW PATH FROM
   NEAR LBB TO CDS TO LAW THROUGH 12Z. 05Z SFC ANALYSIS INDICATES THAT
   SFC DEWPT DEPRESSIONS REMAIN FROM 10-15 DEG F WHICH ALONG WITH ABOUT
   A 100-150 MB DEEP DRY LAYER ABOVE SFC SHOULD LIMIT INITIAL
   DEVELOPMENT AND INTENSITY OF SNOW UNDER THE STRONG MID LEVEL
   FORCING. DESPITE A CONTINUATION OF LOW LVL DRY AIR ADVECTING IN ON
   NELY SFC WINDS...SUFFICIENTLY STRONG PRECIPITATION DEVELOPMENT
   SHOULD OFFSET THE DRYING WHICH WILL SUPPORT HVY SNOWFALL AT THE SFC
   WITHIN 1-2 HOURS OF LIGHT SNOW DEVELOPMENT. DEGREE OF LIFT
   ASSOCIATED WITH BANDED PRECIP ALONG WITH MID LEVEL LAPSE RATES
   AROUND 7 DEG C/KM WILL SUPPORT CONVECTIVE SNOWFALL RATES AROUND 1
   INCH/HR.
   
   ..CROSBIE.. 12/22/2004
   
   
   ...NOTICE...
   SPC WINTER WEATHER MESOSCALE DISCUSSIONS WILL BE ISSUED ON A 
   SCHEDULED BASIS...FOUR TIMES A DAY...BETWEEN 00-01 UTC...
   06-07 UTC...12-13 UTC...AND 18-19 UTC AS SIGNIFICANT SHORT
   RANGE WINTER WEATHER EVENTS UNFOLD.  THIS SCHEDULE WILL BE
   USED FROM DECEMBER 1 THROUGH FEBRUARY 28.
   
   ATTN...WFO...OUN...LUB...AMA...
   
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