Severe Thunderstorm Warning 128, NWS Gaylord, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1100 AM EDT MON JUN 29 1998

WEAK SFC BOUNDARY STRETCHES FROM SRN LOWER MI INTO SRN WI AND IA...WITH
A COLD FRONT EXTENDING FROM LAKE SUPERIOR INTO FAR NW WI AND MN. MCS S
OF THE BOUNDARY OVER MO AND IL HAS SHOWN WARMING CLOUDS TOPS OVER THE
PAST FEW HOURS. HOWEVER...TOPS APPEAR TO BE COOLING AGAIN OVER STL...
BUT EXPECT THIS WILL NOT LAST TOO MUCH LONGER AS FOCUS FOR CONVECTIVE
DEVELOPMENT TURNS TO AREAS N OF MO OVER IA AND SRN MN. HIGHER DWPTS ARE
BEGINNING TO POOL AROUND THE STATIONARY FRONT OVER THIS AREA AND EXPECT
THIS WILL BE THE HOT SPOT FOR DEEP CONVECTIVE DEVELOPMENT THIS
AFTERNOON. GRIDDED DATA INDICATES RAPIDLY INCREASING UPPER LEVEL
DIVERGENCE IN THIS AREA VIA THE RIGHT ENTRANCE REGION OF A 250 JET MAX.
NO SURPRISE THEN THAT THE LATEST IR SATELLITE LOOP INDICATES THE VERY
BEGINNING OF CONVECTION OVER ERN SD...SRN MN AND IA ATTM.

GIVEN THE ABOVE PARAMETERS PLUS STATIONARY BOUNDARY NEARLY PARALLEL TO
THE 500 MB FLOW...MODERATELY STRONG BUT CONSISTANT MID LEVEL WINDS AND
CAPES APPROACHING 3000 J/KG IN AN AREA STRETCHING FROM IA TO NRN
MO...IL AND IN...MAIN CONCERN IN THIS AREA FOR THE AFTERNOON WILL BE
POTENTIAL FOR DERECHO TYPE EVENT. SRN LOWER WILL BE ON THE NRN FRINGE
OF THESE PARAMETERS AND COULD VERY WELL GET CLIPPED BY SOME
STRONG/SEVERE STORMS MAINLY THIS EVENING.

BUT FOR NRN LOWER MI...EXPECT ONLY WIDELY SCT TSRA DEVELOPMENT DURING
MAX HEATING WITH ONLY A SLIGHT CHANCE OF MARGINAL SVR TSRA. Q-VECTORS
AT 700/500 MB LEVEL DO INDICATE SOME WEAK QG FORCING LATE THIS
AFTERNOON/EVENING FOR NRN LOWER...BUT 850 DWPTS CONTINUE TO DROP WITH
TIME. INSTABILITY IS NOT VERY IMPRESSIVE...WITH CAPES OF 1000...LIS OF
-2 AND TTS IN THE LOW 40S. WEAK CAA WILL HELP TO DESTABILIZE LATE
AFTERNOON/EVENING. COLD FRONT WILL APPROACH NRN LOWER TOWARD 00Z AND
MAY PROVIDE SOME FOCUS. BUT WITH LACK OF MOISTURE AND RAPID LOSS OF
DIURNAL INSTABILITY AT THAT TIME...EXPECT ONLY WIDELY SCT SHRA/TSRA
LATE TODAY INTO THIS EVENING. WILL UPDATE ZONES TO FRESHEN WORDING...
BUT OVERALL FORECAST CONTENT LOOKS ON TARGET FOR NOW.

EME