MESOSCALE DISCUSSION 0054
   NWS STORM PREDICTION CENTER NORMAN OK
   1131 PM CST TUE JAN 27 2009
   
   AREAS AFFECTED...MID-MS VALLEY TO THE NORTHEAST
   
   CONCERNING...WINTER MIXED PRECIPITATION 
   
   VALID 280531Z - 281030Z
   
   MAJOR WINTER STORM WILL PIVOT EWD ACROSS THE OH VALLEY AND EXPAND
   NWD IN THE NORTHEAST. THROUGH 12Z...LIQUID-EQUIVALENT RATES OF 0.05
   TO 0.15 IN/HR WILL REMAIN COMMON. FREEZING RAIN SHOULD DEVELOP
   INTO/BE MOST PREVALENT FROM THE MEMPHIS TN TO CINCINNATI OH TO
   PITTSBURGH PA TO BALTIMORE MD METRO AREAS. SLEET WILL SHIFT INTO THE
   JONESBORO AR TO COLUMBUS OH TO PHILADELPHIA PA AREAS. MODERATE TO
   HEAVY SNOW WITH RATES NEAR 1 IN/HR SHOULD DEVELOP IN AN AXIS FROM
   EVANSVILLE IND TO AKRON OH TO BINGHAMTON NY.
   
   EVENING MODEL FORECASTS REMAIN CONSISTENT WITH THE ACCELERATION OF
   POTENT SHORT WAVE TROUGH /CURRENTLY STRETCHING FROM THE LOWER MO
   VALLEY TO THE SRN PLAINS PER WATER VAPOR IMAGERY/. ATTENDANT
   INCREASE IN DOWNSTREAM HEIGHT FALLS WILL LEAD TO INTENSIFYING
   CYCLOGENESIS WITH SURFACE CYCLONE JUST N OF TUP AT 05Z TRACKING NEWD
   TO NEAR HTS AT 12Z. A STRENGTHENING LLJ WILL RESULT IN SUBSTANTIAL
   WARM THETA-E ADVECTION INTO THE NORTHEAST WITH PRECIPITATION
   RATES/AREAL COVERAGE INCREASING. ELEVATED WARM NOSE OF
   ABOVE-FREEZING TEMPERATURES WILL CORRESPONDINGLY SHIFT NWD LEADING
   TO TRANSITIONS OF SNOW TO SLEET TO FREEZING RAIN. FARTHER
   WEST...LOW-LEVEL COLD ADVECTION WILL STRENGTHEN ON THE BACKSIDE OF
   THE DEVELOPING CYCLONE ACROSS THE MID-MS TO LOWER OH VALLEYS. THIS
   WILL RESULT IN A SEWD SHIFT IN PTYPE TRANSITIONS FROM RAIN TO
   FREEZING RAIN TO SLEET TO SNOW. GIVEN THE EXPANSIVE PRECIPITATION
   SHIELD /INTO CNTRL TX AS OF 0515Z/ AND STRONG UPPER-LEVEL FORCING
   ASSOCIATED WITH THE SHORT WAVE TROUGH...SEVERAL MORE HOURS OF
   SIGNIFICANT FROZEN PRECIPITATION CAN BE EXPECTED ACROSS THE MID-MS
   AND LOWER OH VALLEYS.
   
   ..GRAMS.. 01/28/2009
   
   
   ...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...OKX...ALY...PHI...BGM...AKQ...BUF...CTP...LWX...
   PBZ...RLX...CLE...JKL...ILN...LMK...IWX...OHX...IND...PAH...ILX...
   MEG...
   
   LAT...LON   41768095 42517846 42557667 42277543 41487408 40917368
               39967417 39087477 38617545 38677645 39057753 39457881
               39498042 38858178 37978359 36878623 34888909 34569051
               34989092 35569098 36719096 37798940 39678623 41298224
               41768095