SWOMCD
SPC MCD 161823
SCZ000-GAZ000-NCZ000-TNZ000-ALZ000-162230-
MESOSCALE DISCUSSION 0069
NWS STORM PREDICTION CENTER NORMAN OK
1223 PM CST WED JAN 16 2008
AREAS AFFECTED...NRN GA
CONCERNING...WINTER MIXED PRECIPITATION
VALID 161823Z - 162230Z
A 2-3 HR PERIOD OF SNOW SHOULD DEVELOP OVER NRN GA TOWARDS 00Z AS AN
EXPANSIVE SWATH OF PRECIPITATION LIFTS SLOWLY NWD FROM THE ERN GULF
COASTAL PLAINS. MODERATE SNOWFALL RATES /AROUND 0.5 IN PER HR/
APPEAR LIKELY FROM THE I-20 CORRIDOR NWD GIVEN INITIAL PRESENCE OF
COLD/DRY AIR MASS IN LOW-LEVELS.
LOW-LEVEL WARM THETA-E ADVECTION DOWNSTREAM OF LOWER MS RIVER VALLEY
SHORT WAVE TROUGH IN COMBINATION WITH FAVORABLE DIVERGENCE S/SW OF
OH RIVER VALLEY/MID-ATLANTIC UPPER-LEVEL JET...WILL PROMOTE
PRECIPITATION SPREADING N/NEWD FROM THE GULF COASTAL PLAINS INTO THE
SRN APPALACHIANS. LATEST SUBJECTIVE SURFACE ANALYSIS INDICATES
CONTINUED RIDGING OVER NRN GA FROM HIGH PRESSURE CENTERED OVER THE
COASTAL CAROLINAS. MODEST ELY SURFACE WINDS ALONG WITH OVERCAST
SKIES/VIRGA HAVE SLOWED DIURNAL WARMING WITH SURFACE TEMPERATURES
GENERALLY HOLDING IN THE UPPER 30S. BOTH 12Z NAM/09Z NAMKF FORECAST
SOUNDINGS ARE AROUND 3 TO 8 DEG F TOO HIGH WITH BOTH
TEMPERATURES/DEW POINTS COMPARED TO 18Z SURFACE OBS. HOWEVER...THE
12Z GFS APPEARS TO MORE CLOSELY RESEMBLE THE LOW-LEVEL THERMODYNAMIC
PROFILE WHEN COMPARED TO ACARS/SURFACE OBS WITH WET-BULB
TEMPERATURES BELOW FREEZING ATTM. DESPITE STRENGTHENING LOW-LEVEL
WAA...INCREASING UPWARD VERTICAL MOTION/SATURATION SHOULD LEAD TO
DEEP ISOTHERMAL PROFILES BY 17/00Z...AS DEPICTED BY THE GFS.
ALTHOUGH PTYPE ALGORITHMS PREDOMINATELY SUGGEST RAIN...INITIAL LIGHT
RAIN/SLEET MIX SHOULD LARGELY TRANSITION TO NEARLY ALL SNOW AS FULL
SATURATION OCCURS. WITH TIME THIS EVENING...THE MAGNITUDE OF WAA
SHOULD RESULT IN A TRANSITION BACK TO RAIN WITH SNOW/FREEZING RAIN
RELEGATED TO THE FAR NRN GA MTNS.
.GRAMS.. 01/16/2008
..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...CAE...GSP...MRX...FFC...BMX...HUN...
34708330 34318256 34028243 33608278 33378340 33438434
33648502 34108558 34628550 35048515 35088475 34928387
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