MESOSCALE DISCUSSION 0162
   NWS STORM PREDICTION CENTER NORMAN OK
   1125 AM CST FRI FEB 27 2009
   
   AREAS AFFECTED...S CNTRL SD/N CNTRL AND ERN NEB
   
   CONCERNING...HEAVY SNOW 
   
   VALID 271725Z - 272130Z
   
   OCCASIONAL MODERATE TO HEAVY SNOWFALL HAS BEEN OBSERVED RECENTLY
   ACROSS S CNTRL SD AND N CNTRL NEB. EXPECT A GENERAL INCREASE IN
   COVERAGE THROUGH THE AFTERNOON AS SNOW SHIFTS SEWD THROUGH S CNTRL
   SD...N CNTRL NEB...AND INTO ERN NEB. SNOWFALL RATES NEAR 1 TO 2
   INCHES AN HOUR WILL BE POSSIBLE IN THE HEAVIEST SNOW...ALONG WITH
   REDUCED VISIBILITIES.
   
   A STRONG SHORT WAVE TROUGH...CURRENTLY NEAR THE ERN MT/NERN WY
   BORDERS...WILL CONTINUE TO MOVE SEWD INTO WRN SD/NEB PROVIDING
   FAVORABLE JET DYNAMICS FOR INCREASING SNOWFALL THROUGH THE
   AFTERNOON. RADAR IMAGERY SHOWS A NW TO SE ORIENTED SWATH OF MODERATE
   TO HEAVY SNOWFALL AHEAD OF A SURFACE LOW LOCATED IN CNTRL CO. THE
   SURFACE LOW WILL DEVELOP SSEWD THROUGH THE DAY. AS THIS
   OCCURS...ISENTROPIC LIFT WILL BECOME ALIGNED FAVORABLY WITH
   INCREASING UPPER DIVERGENCE ACROSS CNTRL NEB...BEFORE MOVING SEWD
   INTO ERN NEB. INITIAL 12Z SOUNDINGS REFLECTED A VERY DRY ARCTIC
   AIRMASS. HOWEVER...GOES PWAT IMAGERY IN ADDITION TO WV INDICATES
   SLOW MOISTURE RETURN IN SELY LOW LEVEL FLOW...WITH THE MOIST AXIS
   THROUGH CNTRL/ERN NEB AND THE NOSE JUST REACHING INTO CNTRL SD. THIS
   IN COMBINATION WITH ONGOING SNOWFALL WILL SLOWLY CONTINUE TO
   SATURATE LOW LEVELS. ADDITIONALLY...ELONGATED ISOTHERMAL LAYER JUST
   ABOVE THE SURFACE THROUGH APPROXIMATELY 750 MB BENEATH DENDRITIC
   GROWTH LAYER WILL BE FAVORABLE FOR MODERATE TO HEAVY SNOWFALL.
   
   ..HURLBUT.. 02/27/2009
   
   
   ATTN...WFO...FSD...OAX...ABR...GID...LBF...UNR...
   
   LAT...LON   41939636 41079670 40659803 40829936 41640074 42810173
               44000164 44770049 44419806 42799655 41939636