[MCD] SWOMCD

Mon Feb 20 12:41:10 UTC 2006

ACUS11 KWNS 201240
SWOMCD
SPC MCD 201239 
GAZ000-ALZ000-MSZ000-ARZ000-LAZ000-201815-

MESOSCALE DISCUSSION 0161
NWS STORM PREDICTION CENTER NORMAN OK
0639 AM CST MON FEB 20 2006

AREAS AFFECTED...PORTIONS SRN AR...NRN LA...W-CENTRAL/N-CENTRAL
MS...N-CENTRAL AL.

CONCERNING...FREEZING RAIN 

VALID 201239Z - 201815Z

FREEZING MIST/DRIZZLE AND ASSOCIATED HAZARDS ARE POSSIBLE VIRTUALLY
ANYWHERE BETWEEN NWRN TX/SWRN OK REGION AND EXTREME NRN GA/SERN
TN...HOWEVER GREATEST PROBABILITY OF CRITERIA RATES AT LEAST .05
INCH/3-HOUR WILL REMAIN OVER SRN AR...NRN LA...N-CENTRAL MS AND
N-CENTRAL AL BEFORE 18Z.

12Z SFC MESOANALYSIS SHOWS FREEZING LINE ROUGHLY ALONG CHA...15 N
TCL...20 SSW CBM...50 NNE HEZ...POE...LFK.  OBSERVED AND MODIFIED
12Z RAOBS FROM SHV-JAN...AS WELL AS FCST RUC SOUNDINGS OVER
SUBFREEZING SFC LOCATIONS...SHOW DEEP SUPERFREEZING LAYER ABOVE
SHALLOW NEAR-SFC ZONE OF MARGINALLY FREEZING TEMPERATURES.  FURTHER
WET BULB COOLING OF SFC AIR IS NOT EXPECTED GIVEN SATURATED BOUNDARY
LAYER CONDITIONS.  IN FACT...DOWNWARD TRANSFER OF HEAT BY LIQUID
PRECIP...FROM WARMER LAYER ALOFT...SHOULD RESULT IN NWD DRIFT OF
FREEZING LINE. SERIES OF WEAK PERTURBATIONS ALOFT -- EMBEDDED
WITHIN NEARLY ZONAL JET CORE -- WILL AID IN MAINTAINING ELONGATED
CONVEYOR OF ASCENT THROUGH REMAINDER FORENOON HOURS...STRONGEST FROM
NEAR MS RIVER EWD ACROSS CENTRAL AL.  THEREAFTER...RUC AND SREF
PROGS INDICATE FORCING WILL WEAKEN...AND FREEZING LINE WILL DRIFT
NWD MORE.  THIS WILL CAUSE A CHANGE TO COLD RAIN AND DRIZZLE FROM
S-N...WHEREVER PRECIP STILL LINGERS.

..EDWARDS.. 02/20/2006

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

ATTN...WFO...FFC...BMX...HUN...MEG...JAN...LZK...LCH...SHV...

32439054 31949149 31299261 31069313 31169329 31419349
32589369 33219309 33389236 34228878 34598548 33718689
33368831 32788976 

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