Severe Thunderstorm Warning 67, NWS Grand Rapids, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
436 AM EDT MON JUL 7 2003

ONCE AGAIN MAIN FOCUS IN THE SHORT TERM WAS ON PCPN POTENTIAL OVER
THE NEXT 48 HOURS.  SEVERE THUNDERSTORMS ARE A THREAT AGAIN THIS
EVENING AND OVERNIGHT.

COMPLEX PATTERN CONTINUES AS MODELS VARY ON THE HANDLING OF SHORT
WAVES WHICH ARE EMBEDDED IN AN OTHERWISE ZONAL FLOW.  WAVE VAPOR
IMAGES REVEAL FIRST SHORT WAVE IS NOW NEAR THE THUMB AND CONTINUES
TO HEAD EAST.  MOST SHOWERS HAVE ALREADY EXITING THE CWA...SO WILL
HAVE A DRY MORNING.  ADDITIONAL SHORT WAVES ARE ALONG THE
ND/CANADIAN BORDER AND WITH YET ANOTHER ALONG THE SD/NE BORDERS.
HAVE GENERALLY SIDED WITH THE ETA FOR THE TIMING OF THESE FEATURES.

A DRY WEDGE HAS FORMED BETWEEN THE EXITING SHORT WAVE OVER THE THUMB
AND THE PAIR OF SHORT WAVES OVER THE PLAINS.  CONVECTION HAS
DEVELOPED OVER ERN MN/IA THIS MORNING.  THIS IS IN A REGION OF
STRONG UPPER DIVERGENCE AND WHERE LOW LEVEL MOISTURE IS POOLING.
BELIEVE THIS CONVECTION WILL DISSIPATE BEFORE REACHING WESTERN MI AS
THE UPPER DIVERGENCE HEADS NORTHEAST TOWARD THE U.P. AND THE
CONVECTION MOVES AWAY FROM THE LOW LEVEL MOISTURE.  MOISTURE OVER
WESTERN MI WILL ALSO STAY QUITE SHALLOW TODAY SO BELIEVE THE THREAT
FOR CONVECTION IS SMALL DURING THE DAYTIME.  HAVE DECIDED TO CARRY
ONLY A SMALL POP AND THIS SHOULD MAINLY OCCUR TOWARD EVENING AS THE
PLAINS SHORT WAVE APPROACH.  DAYTIME TEMPS WILL BE IMPACTED BY A
FAIR AMOUNT OF CI FROM THE UPSTREAM CONVECTION.  WITH MOSTLY CLEAR
SKIES TEMPS MIGHT PUSH 90...BUT WITH THE HIGH CLOUDS WILL KEEP MAXES
IN THE 80S.

MAIN ACTIVITY SHOULD SLIDE INTO THE CWA BETWEEN 00Z AND 06Z.  BY
THEN THE STRONG PLAINS SHORT WAVE WILL BE MOVING ACROSS WISCONSIN
AND INTO MICHIGAN.  AS THE UPPER SUPPORT MOVES IN A COLD FRONT WILL
ALSO BE PUSHING INTO THE CWA FROM THE NW...ADDING LOW LEVEL
CONVERGENCE.  ANOTHER BULLSEYE OF UPPER DIVERGENCE DEVELOPS OVER THE
WESTERN GREAT LAKES IN THE RIGHT REAR QUAD OF THE JET.  DAYTIME
INSTABILITY SHOULD PUSH EVENING CAPES TO 2000-3000 J/KG WITH LI/S
FROM -5 TO -8C.  4KM SHEAR FAVORS MULTICELLS...BUT A FEW SUPERCELLS
WILL NOT BE OUT OF THE QUESTION.  WITH LOW HELICITY VALUES AND
FREEZING LEVELS BETWEEN 13-14K FT BELIEVE MAIN THREAT FROM THESE
STORMS WILL BE DAMAGING WINDS.  FORECAST SOUNDINGS SHOW MID LEVEL
WINDS NEAR 50KT ALONG WITH MID LEVEL DRYING.

MOVEMENT OF THE COLD FRONT WILL BE SLOW INTO TUESDAY AS THE FRONT
BECOMES PARALLEL TO THE UPPER FLOW.  IT APPEARS IT WILL TAKE MUCH OF
TUESDAY TO EXIT THE SE CORNER OF THE CWA.  AS IT DOES SO YET ANOTHER
SHORT WAVE TRAVERSE IT DURING THE AFTERNOON AND EVENING.  WILL NEED
TO EXTEND POPS INTO TUESDAY OVER THE CENTRAL AND SOUTHERN PORTION OF
THE CWA TO ACCOUNT FOR THIS SHORT WAVE.  WILL ALSO HAVE POPS OVER
THE FAR SOUTH TUESDAY NIGHT UNTIL THE FRONT/SHORT WAVE FINALLY
CLEARS.  ACROSS THE NORTH TEMPS ON TUESDAY WILL BE ABOUT 5 TO 10
DEGREES COOLER AS COLD ADVECTION SETS IN BEHIND THE FRONT.

JK

EXTENDED FORECAST
A RIDGE WILL BE BUILDING IN THE WEST BY WEDNESDAY AND A TROUGH WILL
BEGIN TO FORM IN THE EAST ENDING THE ZONAL FLOW REGIME OF THE PAST
WEEK. THIS WILL HELP TO PUSH THE BOUNDARY RESPONSIBLE FOR THE RECENT
WEATHER FARTHER SOUTH LEAVING WEDNESDAY DRY. A SURFACE LOW PRESSURE
SYSTEM WILL MOVE BY SOUTH OF MICHIGAN LATE THURSDAY INTO FRIDAY
BRINGING A SHORT PERIOD OF RAIN AND THUNDERSTORMS TO SOUTHERN
PORTIONS OF THE FORECAST AREA. THE REST OF THE EXTENDED FORECAST
WILL BE COOL...DRY AND PARTLY CLOUDY AS CANADIAN AIR FLOWS DOWN THE
WESTERN RIDGE. WILL ONLY TWEAK THE GOING FORECAST A LITTLE AS THE
CURRENT FORECAST IS ON THE MONEY.

IOD

.GRR...NONE.

MIZ037>040-043>046-050>052-056>059-064>067-071>074-081000-

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1005 AM EDT MON JUL 7 2003

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

.DAY ONE...TONIGHT

A FEW THUNDERSTORMS ARE POSSIBLE TONIGHT...MAINLY ALONG AND SOUTH OF
THE INTERSTATE 94 CORRIDOR. AN ISOLATED SEVERE THUNDERSTORM CANNOT
BE RULED OUT IN THIS AREA...BUT THE MAIN SEVERE WEATHER THREAT IS
SOUTH OF MICHIGAN TONIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THE STORM PREDICTION CENTER HAS PLACED FAR SOUTHERN LOWER MICHIGAN
IN A SLIGHT RISK AREA FOR SEVERE STORMS ON TUESDAY. THIS WOULD
INCLUDE AREAS FROM SOUTH HAVEN TO BATTLE CREEK TO JACKSON. THESE
STORMS SHOULD MAINLY OCCUR IN THE AFTERNOON AND EARLY EVENING HOURS
OF TUESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION SHOULD NOT BE NEEDED TONIGHT...BUT MAY BE
NECESSARY ON TUESDAY.

JK MWH

MIZ064>067-071>074-071800-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
944 AM EDT MON JUL 7 2003

THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH
FOR THE SOUTHWEST QUARTER OF LOWER MICHIGAN EFFECTIVE UNTIL
2 PM EDT THIS AFTERNOON. THIS WATCH INCLUDES THE FOLLOWING COUNTIES

IN SOUTHWEST MICHIGAN
     ALLEGAN...BARRY...KALAMAZOO...VAN BUREN

IN SOUTH CENTRAL MICHIGAN
     JACKSON...CALHOUN...EATON...INGHAM

A SEVERE THUNDERSTORM WATCH MEANS THAT CONDITIONS ARE FAVORABLE FOR
THE DEVELOPMENT OF SEVERE THUNDERSTORMS IN AND NEAR THE WATCH AREA.
REMEMBER...SEVERE THUNDERSTORMS PRODUCE WIND GUSTS IN EXCESS OF 58
MPH AND/OR HAIL THREE-QUARTERS OF AN INCH IN DIAMETER OR GREATER. IF
YOU LIVE IN OR NEAR THE WATCH AREA YOU SHOULD REMAIN ALERT TO RAPIDLY
CHANGING WEATHER CONDITIONS. STAY TUNED TO NOAA WEATHER RADIO OR THE
LOCAL NEWS OUTLETS FOR THE LATEST UPDATES AND POSSIBLE WARNINGS.

BEACH MWH