MESOSCALE DISCUSSION 0175 NWS STORM PREDICTION CENTER NORMAN OK 1147 AM CST SAT FEB 28 2009 AREAS AFFECTED...SERN MO...NERN AR...WRN TN/KY CONCERNING...HEAVY SNOW VALID 281747Z - 282145Z MODERATE TO HEAVY SNOW HAS OCCASIONALLY BEEN OBSERVED ACROSS S CNTRL MO OVER THE PAST FEW HOURS...WITH A RECENT REPORT OF 2 INCHES AN HOUR AT FT WOOD. ANTICIPATE THIS TREND TO CONTINUE ESEWD TOWARD SERN MO...NERN AR...AND WRN TN/KY. RATES OF NEAR 1 TO 2 INCHES AN HOUR CAN BE EXPECTED IN HEAVIER SNOWFALL IN ADDITION TO RESTRICTED VISIBILITIES. A VIGOROUS UPPER LOW...CURRENTLY LOCATED OVER ERN KS...WILL QUICKLY DIVE SEWD REACHING CNTRL AR BY 00Z. AT THE SURFACE...STRONG ARCTIC HIGH PRESSURE IS QUICKLY BUILDING ACROSS THE CNTRL STATES...AND SUBFREEZING TEMPERATURES WILL REMAIN ACROSS THE OUTLINE AREA WHILE AREAS TO THE SOUTH AND EAST WILL QUICKLY COOL THROUGH THE AFTERNOON IN STRONG COLD AIR ADVECTION. A NW TO SE ORIENTED BAND OF MDT/HVY SNOW IS OCCURRING AHEAD OF THE UPPER LOW...WITH ADDITIONAL DEVELOPMENT BEGINNING INTO SERN MO...WRN KY/TN...AND NERN AR ALONG AN INVERTED SURFACE TROUGH AXIS AND IN CONJUNCTION WITH STRONG UPPER DIVERGENCE/FAVORABLE JET DYNAMICS. SUBTLE ISENTROPIC LIFT IS CONTRIBUTING AS WELL...WITH RELATIVE WARM/MOIST AIR TO THE EAST BEING DRAWN ATOP THE ARCTIC AIRMASS/SUBFREEZING TEMPERATURES TO THE WEST. THIS IS REFLECTED WELL IN RECENT PADUCAH VAD WIND PROFILES. 12Z SPRINGFIELD SOUNDING SHOWS SATURATED COLUMN GENERALLY FROM THE SURFACE THROUGH 500 MB...AND MODEL SOUNDINGS ARE INDICATIVE THAT AREAS IMMEDIATELY DOWNSTREAM WILL REMAIN SATURATED AS WELL...PROMOTING MDT/HVY SNOW. EXPECT THIS TREND TO GENERALLY SHIFT ESEWD IN CONJUNCTION WITH THE MOVEMENT OF THE UPPER LOW. ..HURLBUT.. 02/28/2009
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