[MCD] SWOMCD

[MCD at goshenarc.org]

ACUS11 KWNS 280046
SWOMCD
SPC MCD 280046 
VAZ000-NCZ000-WVZ000-TNZ000-SCZ000-GAZ000-280645-

MESOSCALE DISCUSSION 0241
NWS STORM PREDICTION CENTER NORMAN OK
0646 PM CST SUN FEB 27 2005

AREAS AFFECTED...WRN NC..FAR ERN TN AND SWRN VA/FAR SRN WV

CONCERNING...WINTER MIXED PRECIPITATION 

VALID 280046Z - 280645Z

HVY SNOW POSSIBLY CHANGING OVER TO COLD RAIN/FREEZING RAIN WILL
DEVELOP ACROSS THE REGION THROUGH 06Z. PRECIPITATION WILL LIKELY
START OUT AS HVY SNOW OVER WRN NC ...BUT WILL LIKELY TRANSITION OVER
TO EITHER COLD RAIN/FREEZING RAIN BELOW 4500 FT THROUGH THE EVENING
HOURS AS AN ELEVATED WARM LAYER DEEPENS IN THE STRONG WAA REGIME.
FARTHER NORTHWEST...WHERE COLD AIR SHOULD REMAIN DEEPER AND/OR LOW
LEVEL WARM ADVECTION SLIGHTLY WEAKER...EXPECT HVY SNOW TO BE THE
PREDOMINANT PTYPE OVER THE HIGHEST ELEVATIONS OF WRN NC...AND OVER
SWRN VA/FAR ERN TN AND FAR SRN WV BETWEEN 02-06Z. HRLY SNOWFALL
RATES UP TO 2 INCHES WILL BE POSSIBLE...ESPECIALLY ACROSS THE WRN
SLOPES OF THE SMOKY AND BLUE RIDGE MTNS WHERE STRONG ELY FLOW
CENTERED AROUND 850 MB WILL AID IN STRONG OROGRAPHIC COMPONENT TO
THE LOW LEVEL VERTICAL MOTION FIELD.

A DYNAMIC UPPER SYSTEM WILL CONTINUE TO MOVE NEWD THROUGH THE
REGION. THE STRONGEST VERTICAL MOTION THROUGH THE COLUMN WILL OCCUR
WHERE A STRONG WAA REGIME OVERLAYS AN UPPER LEVEL DIVERGENCE FIELD.
THIS WAS PRESENTLY OCCURRING OVER AL...WHERE HRLY RAINFALL RATES
OVER 0.2 INCHES HAVE BEEN NOTED IN THE LAST 2 HOURS. EXTRAPOLATING
CURRENT TRENDS AND RECENT PRECIPITATION DEVELOPMENT OVER NRN
GA...EXPECT THIS STRONGEST VERTICAL MOTION FIELD TO MOVE NEWD INTO
THE SRN APPALACHIAN REGION BETWEEN 02-06Z. GIVEN DEGREE OF FORCING
IN THE FORECAST SOUNDINGS OCCURRING BETWEEN THE -12 AND -16 DEG C
LAYER...DENDRITIC SNOW GROWTH WILL BE MAXIMIZED TO SUPPORT HRLY
SNOWFALL RATES OVER 1 INCH. IN ADDITION...WHERE THE WARM LAYER IS
NOT SUFFICIENTLY DEEP TO ALLOW FOR A CHANGEOVER TO FREEZING
RAIN/RAIN...A 15O MB DEEP LAYER FROM THE SFC TO 700 MB OF AGGREGATE
SNOW GROWTH WILL FURTHER SUPPORT HVY SNOWFALL. SINCE THE 00Z GSO
SOUNDING IS ABOUT 2 DEGREES COOLER THAN THE VALID NAM/RUC FORECAST
SOUNDINGS AT 850 MB...THE DEGREE OF THE ELEVATED WARMING THROUGH THE
EVENING IN THE LOWER LEVELS IS LIKELY TO BE SOMEWHAT WEAKER THAN
SUGGESTED BY THE MODELS. HOWEVER...WITH EVAPORATIVE COOLING EFFECTS
THERE IS LIKELY TO BE SUFFICIENT COOLING NEAR THE SFC...THAT WHERE
THE ELEVATED WARM LAYER IS PRESENT...TEMPERATURES NEAR FREEZING WILL
SUPPORT EITHER VERY COLD RAIN/FREEZING RAIN OVER THE FOOTHILLS AND
HIGHER ELEVATIONS ABOVE 1500 FT OF THE PIEDMONT OF WRN NC.

..CROSBIE.. 02/28/2005

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

ATTN...WFO...RAH...RNK...RLX...GSP...MRX...

36687958 37507991 37688100 36658263 35718365 35148403
34908325 36138039 

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