Severe Thunderstorm Warning 155, NWS Grand Rapids, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1047 PM EDT MON AUG 25 2003

ELEVATED CONVECTION CONTINUES THIS EVENING ALONG A WEAKLY DEFINED
SURFACE BOUNDARY.  A SHORT WAVE WAS MOVING INTO WESTERN MI AT 02Z
AND WILL BE TO THE EASTERN PORTION OF THE STATE SHORTLY AFTER
MIDNIGHT.  A STORM OR TWO COULD BECOME SEVERE WITH HAIL BEING THE
MAIN THREAT.  THERE SHOULD BE A BRIEF PAUSE IN THE ACTIVITY AFTER
04Z AS THIS WAVE EXITS.  ANOTHER SHORT WAVE WAS SPAWNING STORMS OVER
EASTERN IA.  THIS WAVE SHOULD MOVE TO SOUTHERN LAKE MICHIGAN BY
12Z.  THIS SHOULD PUSH ANOTHER ROUND OF STORMS INTO WESTERN MI AFTER
08Z.  THE 00Z ETA LOW LEVEL JET IS NOT TOO IMPRESSIVE...ONLY
30KT...AND POINTS TOWARD SOUTHERN LAKE MI/NORTHERN INDIANA.  THIS
WOULD MAINLY FAVOR THE SOUTHERN CWA FOR THE BEST CHC OF SEEING THE
NEXT ROUND OF STORMS.  ALSO 1000-500 THICKNESS WOULD SUPPORT THE IA
STORMS TRACKING EAST...THEN SOUTHEAST AS THEY MOVE TOWARD SOUTHERN
MI.  WITH PRECIPITABLE WATER VALUES PEAKING ABOVE 2 INCHES AFTER
MIDNIGHT HEAVY DOWNPOURS ARE A GOOD BET AND A COUPLE OF ISOLATED
SEVERE STORMS CAN NOT BE RULED OUT.  STORMS SHOULD MOVE AT
35-40KT...BUT SOME CELLS MAY TRAIN SO SOME URBAN OR SMALL STREAM
FLOODING IS POSSIBLE.  WILL CARRY CATEGORICAL POPS SOUTH...LIKELY
CENTRAL...AND KNOCK THE POPS DOWN TO CHC IN THE NORTH.

JK

.GRR...NONE.

MIZ037>040-043>046-050>052-056>059-064>067-071>074-261000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
213 PM EDT MON AUG 25 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE SOUTHWEST QUARTER OF LOWER
MICHIGAN.

.DAY ONE...THIS AFTERNOON AND TONIGHT

SCATTERED THUNDERSTORMS SHOULD FORM THIS AFTERNOON AND NUMEROUS
STORMS ARE FORECASTED FOR TONIGHT ACROSS THE
SOUTHWEST QUARTER OF LOWER MICHIGAN. THE STORM PREDICTION CENTER HAS
PLACED THE ENTIRE AREA IN A SLIGHT RISK FOR SEVERE THUNDERSTORMS.
THE BEST CHANCE FOR STORMS WILL BE THIS EVENING AS A
WARM FRONT LIFTS NORTH THROUGH THE AREA AND THEN AGAIN OVERNIGHT AS
A COLD FRONT APPROACHES FROM THE NORTHWEST.

THE STRONGEST OF STORMS...MOST LIKELY TONIGHT...WILL BE CAPABLE OF
WINDS TO 60 MPH AND HAIL TO AROUND AN INCH IN DIAMETER.
FREQUENT CLOUD TO GROUND LIGHTNING STRIKES AND HEAVY RAIN WILL
ACCOMPANY THE STORMS.

WHERE THE STORMS PERSIST LONGER THAN AN HOUR...MORE THAN 2 INCHES OF
RAIN COULD FALL.  THIS WOULD LEAD TO URBAN AND POOR DRAINAGE
FLOODING.  THE MOST LIKELY TIME FRAME FOR THIS TO OCCUR IS AFTER
MIDNIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THE AREA IS ALSO IN A SLIGHT RISK FOR SEVERE THUNDERSTORMS ON
TUESDAY. THE COLD FRONT WILL PROGRESS THROUGH THE AREA INTO A VERY
MOIST AND UNSTABLE AIRMASS. STRONG STORMS COULD BE ONGOING TO START
THE DAY. DURING THE AFTERNOON...ANOTHER ROUND OF THUNDERSTORMS IS
EXPECTED. THESE STORMS COULD ALSO CONTAIN WINDS TO 60 MPH AND HAIL
TO AROUND AN INCH IN DIAMETER.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS EVENING OR TONIGHT.

RJD MJS