MESO: Mesoscale Discussion 2145

ACUS11 KWNS 272256
SWOMCD
SPC MCD 272256
SCZ000-GAZ000-280030-

MESOSCALE DISCUSSION 2145
NWS STORM PREDICTION CENTER NORMAN OK
0556 PM CDT TUE OCT 27 2009

AREAS AFFECTED...PARTS OF SE GE INTO SRN/CNTRL SC

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 272256Z - 280030Z

TRENDS ARE BEING MONITORED FOR THE POSSIBILITY OF AN INCREASING
SEVERE THREAT THAT COULD REQUIRE A WATCH.

A WEAK SHORT WAVE IMPULSE APPEARS TO BE IN THE PROCESS OF
ACCELERATING NORTHEASTWARD TO THE LEE OF THE SOUTHERN
APPALACHIANS...DOWNSTREAM OF THE MUCH STRONGER CLOSED LOW/SHORT WAVE
TROUGH LIFTING FROM THE LOWER MISSISSIPPI VALLEY INTO THE LOWER
OHIO/TENNESSEE VALLEYS. AS THESE PROCESSES CONTINUE EARLY THIS
EVENING...MID-LEVEL FORCING FOR UPWARD VERTICAL MOTION ACROSS THE
MUCH OF THE SOUTHEAST WILL WEAKEN...AND MODELS SUGGEST THAT A
LINGERING PRE-FRONTAL BELT OF ISENTROPIC ASCENT WILL GRADUALLY SHIFT
EASTWARD FROM UPSTATE SOUTH CAROLINA/EASTERN GEORGIA AND NORTHERN
FLORIDA. THIS BAND MAY REACH THE LEE OF THE BLUE RIDGE THROUGH
CENTRAL NORTH CAROLINA INTO SOUTH CAROLINA COASTAL AREAS EAST OF
CHARLESTON BY 03-04Z.

WIDESPREAD MOSTLY WEAK CONVECTION WITHIN A VERY MOIST RETURN FLOW IS
ONGOING WITH THIS BAND...AND LIKELY TO CONTINUE. HOWEVER...OF
CONCERN IS THE ENHANCED CONVECTIVE ACTIVITY WHERE THIS BAND
INTERSECTS A WARM FRONTAL ZONE WHICH IS SLOWLY ADVANCING INLAND OF
GEORGIA/SOUTH CAROLINA COASTAL AREAS. SURFACE DEW POINTS ARE RISING
THROUGH THE LOWER 70S AS THE FRONT PASSES TO THE NORTH... AND THIS
IS CONTRIBUTING TO WEAK TO MODERATE BOUNDARY LAYER BASED
DESTABILIZATION IN THE PRESENCE OF STRONG LOW-LEVEL SHEAR ALONG AND
EAST OF A 30-50 KT SOUTHERLY 850 MB JET. THIS FRONT MAY ADVANCE
ACROSS SOUTH CAROLINA COASTAL AREAS INTO PARTS OF THE
PIEDMONT...BEFORE THE NORTH/SOUTH BAND OF FORCING SHIFTS EAST OF THE
REGION LATER THIS EVENING. AS THIS OCCURS...THERE APPEARS TO BE A
WINDOW OF OPPORTUNITY FOR INCREASING TORNADIC POTENTIAL ACROSS PARTS
OF CENTRAL/SOUTHERN SOUTH CAROLINA.

..KERR.. 10/27/2009

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...ILM...CHS...CAE...

LAT...LON 33148168 33548135 33668066 33708004 33107911 32647985
31808129 33148168

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