Thursday, January 21, 2010

From the Storm Prediction Center


Slight Risk Area



Highest Tornado Risk Area

Excerpt from SPC Day One Outlook...



MID SOUTH ACROSS THE TN VALLEY INTO SRN/CENTRAL APPALACHIANS... POTENT LOW AND MID LEVEL LOW PRESSURE OVER CENTRAL/NERN AR THIS MORNING WILL PROGRESS EWD ACROSS THE TN VALLEY THROUGH THE DAY. ATTENDANT 70-90 KT WLY MID LEVEL JET WILL LIKEWISE SHIFT ACROSS NRN MS/AL WITH ENHANCED ASCENT AND PRONOUNCED SHEAR OVERSPREADING THIS REGION. LOW LEVEL DESTABILIZATION WILL LIKELY REMAIN TEMPERED BY LOWER TO MID 50S F SURFACE DEW POINTS IN PLACE... ESPECIALLY GIVEN CONVECTIVELY MODIFIED BOUNDARY LAYER ACROSS MUCH OF AL/GA IN WAKE OF OVERNIGHT STORMS. HOWEVER... AXIS OF NEAR 60F DEW POINTS SHOULD BEGIN TO NOSE ACROSS NRN MS AND INTO THE LOWER TN RIVER VALLEY REGION AS SURFACE WINDS VEER TO A MORE SWLY DIRECTION OVER THE LOWERMS RIVER VALLEY. COMBINED WITH STEEPENING LOW LEVEL LAPSE RATES FROM DIURNAL HEATING... EXPECT AXIS OF MODEST INSTABILITY AND STEEPENING LOW LEVEL LAPSE RATES WILL DEVELOP AHEAD OF THE LOW CENTER. SURFACE-BASED STORMS IN THE FORM OF LOW-TOPPED SUPERCELLS/SMALL BOW ECHOES SHOULD EVOLVE DURING THE EARLY AFTERNOON ACROSS THE MID SOUTH AND SPREAD GENERALLY EWD THROUGH THE DAY. SRN EXTENT OF THE GREATER RISK AREA SHOULD BE MODULATED BY DEEPER SUBSIDENCE AND VEERING LOW LEVEL WINDS ACROSS CENTRAL MS/AL... WITHNRN EXTENT POSSIBLY SHIFTING INTO FAR SRN KY AS DESTABILIZATION OCCURS OVER TN. THREAT SHOULD GRADUALLY DIMINISH WITH LOSS OF SFC HEATING TOWARDS THE SRN/CENTRAL APPALACHIANS THIS EVENING.

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