MESOSCALE DISCUSSION 2491
NWS STORM PREDICTION CENTER NORMAN OK
0226 PM CST WED NOV 12 2003
AREAS AFFECTED...SERN MI...NERN IN...NWRN OH
CONCERNING...SEVERE THUNDERSTORM WATCH 943...
VALID 122026Z - 122230Z
LATEST SURFACE MAP SHOWS ENHANCED AREA OF PRESSURE FALLS OVER SERN
MI WITH A 2.5 MB DROP OVER THE LAST HOUR. THESE FALLS ARE
REFLECTIVE OF SURFACE THETA-E ADVECTION AHEAD OF LOW PRESSURE
TROUGH...WHERE TEMPERATURES IN THE 60S AND DEWPOINTS IN THE MID 50S
F EXIST. MODIFIED 18Z DETROIT SOUNDING YIELDS MUCAPE NEAR 1400 J/KG
AND A -7 LI DUE TO VERY COLD MID LEVELS.
VISIBLE IMAGERY AND RADAR SHOWS CELLS DEVELOPING WITHIN LOW PRESSURE
TROUGH OVER NERN IN. THIS TREND IS EXPECTED TO CONTINUE AND CELLS
WILL LIKELY DEVELOP NEWD INTO SERN MI...WHERE THERMODYNAMICS WILL
BECOME INCREASINGLY FAVORABLE FOR LOW TOPPED SEVERE DEVELOPMENT.
STRONG LOW TO MID LEVEL LAPSE RATES SUGGEST POTENTIAL FOR STRONG
UPDRAFT ACCELERATION...AND WHEN COMBINED WITH MODERATE 0-1 SRH
VALUES NEAR 200 M2/S2...MAY YIELD AN ISOLATED TORNADO OR DAMAGING
WIND GUST. EXTREME DEEP LAYER SHEAR IS CURRENTLY PREVENTING RAPID
DEVELOPMENT...BUT A CONTINUATION OF FORCING AND THERMAL ADVECTION
MAY ALLOW FOR ISOLATED SUPERCELLS THROUGH THE AFTERNOON.
..JEWELL.. 11/12/2003
ATTN...WFO...CLE...ILN...DTX...IWX...GRR...IND...
41818485 43118388 42788241 41848343 41438271 40278331
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