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Mesoscale Discussion 71
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   MESOSCALE DISCUSSION 0071
   NWS STORM PREDICTION CENTER NORMAN OK
   1105 AM CST MON FEB 16 2015

   AREAS AFFECTED...PORTIONS OF SW VA...WRN NC...ERN TN...WRN SC...NERN
   GA

   CONCERNING...WINTER MIXED PRECIPITATION 

   VALID 161705Z - 162300Z

   SUMMARY...AREAS OF WINTER MIXED PRECIP WILL BE OVERSPREADING THE SRN
   APPALACHIANS AND VICINITY INTO THE AFTERNOON. AREAS OF SUBSTANTIAL
   ICING WILL BE POSSIBLE ACROSS PARTS OF SWRN NC...WRN SC...AND NERN
   GA.

   DISCUSSION...PLAN-VIEW DEPICTION OF 1.5-KM-AGL VWP DATA INDICATES A
   LLJ EXTENDING FROM THE LOWER MS VALLEY TO THE SRN APPALACHIANS.
   RELATED ISENTROPIC ASCENT CONTINUES TO SUPPORT THE APPROACH OF
   WIDESPREAD PRECIPITATION FROM THE W...WHICH WILL CONTINUE SPREADING
   EWD INTO THE AFTERNOON WITH THE EWD TRANSLATION OF STRONGER POLEWARD
   MASS FLUXES ACCOMPANYING THE LLJ. MEANWHILE...STRENGTHENING UPSLOPE
   FLOW WILL OCCUR ALONG THE SRN/ERN SLOPES OF THE APPALACHIANS...AS AN
   ISALLOBARIC RESPONSE TO PRESSURE FALLS PRECEDING THE SFC LOW AND ITS
   ATTENDANT INVERTED TROUGH -- CURRENTLY ANALYZED OVER LOWER MS
   VALLEY. THIS WILL FURTHER ENHANCE PRECIPITATION RATES INTO THE
   AFTERNOON.

   SFC OBSERVATIONS HIGHLIGHT THE RESIDUAL COLD WEDGE OVER THE
   PIEDMONT...CHARACTERIZED BY SUB-0-C SFC TEMPERATURES. THIS AIR IS
   ALSO VERY DRY...AS INDICATED BY DEWPOINTS IN THE SINGLE DIGITS ABOVE
   AND BELOW 0C. RELATED WET-BULB COOLING AND UPSLOPE-FLOW-FORCED
   ADIABATIC COOLING WILL MAINTAIN SUFFICIENTLY COLD LOWER TROPOSPHERIC
   CONDITIONS FOR FROZEN PRECIPITATION...AS THIS LOW-THETA-E AIR IS
   TRANSPORTED ACROSS THE DISCUSSION AREA.

   HOWEVER...WITH WARMING ALOFT OWING TO WAA ACCOMPANYING THE LLJ...A
   VARIETY OF PRECIPITATION TYPES WILL LIKELY ENSUE ACROSS THE REGION.
   FREEZING RAIN WILL BE MOST LIKELY FROM PARTS OF NERN GA INTO SERN
   TN...WRN SC...AND WRN NC. SLEET AND THEN MODERATE TO HEAVY SNOW WILL
   BE INCREASINGLY LIKELY WITH NNEWD DISPLACEMENT ACROSS THE MCD AREA
   OWING TO COOLER TEMPERATURES IN THE ELEVATED WARM LAYERS -- YIELDING
   INCOMPLETE OR THE ABSENCE OF MELTING OF DESCENDING HYDROMETEORS.

   REGARDING PRECIPITATION RATES...FREEZING RAIN RATES MAY LOCALLY
   REACH 0.05-0.10 INCH PER HOUR...WITH SLEET RATES LOCALLY REACHING
   0.15-0.30 INCH PER HOUR...AND LOCAL SNOW RATES AROUND 1.0-1.5 INCHES
   PER HOUR. THE AFOREMENTIONED SLEET/FREEZING RAIN RATES WILL HAVE THE
   POTENTIAL TO PRODUCE SUBSTANTIAL ICING...ESPECIALLY IN THE VALLEYS
   OF SWRN NC...WRN SC...AND NERN GA...WHERE SHALLOW SUB-FREEZING SFC
   LAYERS WILL LINGER -- AIDED BY THE INFLUX OF DRY CONDITIONS FROM THE
   EAST AND RELATED WET-BULB EFFECTS. THE AFOREMENTIONED PRECIPITATION
   WILL LIKELY CONTINUE INTO THE EVENING.

   ..COHEN.. 02/16/2015


   ATTN...WFO...RNK...GSP...MRX...FFC...

   LAT...LON   34448391 35158421 35738342 36628214 37068036 36338086
               34988195 34418293 34448391 

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Page last modified: February 16, 2015
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