Severe Thunderstorm Warning 155, NWS Grand Rapids, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
316 PM EDT MON AUG 2 2004

.SHORT TERM...
PRIMARY FORECAST CHALLENGE IS FOR POPS TONIGHT THROUGH WEDNESDAY
MORNING. FOR TONIGHT...ONGOING CONVECTION EXPECTED AS LOW LEVEL WARM
AIR ADVECTION COMBINES WITH MOIST UNSTABLE AIRMASS IN PLACE TO
PRODUCE SCATTERED DEEP CONVECTION. ISOLATED SEVERE POTENTIAL FOR
HAIL AND PERHAPS A WET MICROBURST...BUT ORGANIZED SEVERE NOT
EXPECTED EXCEPT PERHAPS ACROSS THE NORTHERN HALF OF THE FORECAST
AREA GIVEN MARGINAL SHEAR PROFILES. EXPECT SCATTERED SHOWERS AND
THUNDERSTORMS TO CONTINUE THROUGH MUCH OF TUESDAY ACROSS THE
SOUTHERN HALF OF THE FORECAST AREA AS LOW LEVEL CONVERGENCE IS
FOCUSSED ALONG SFC FRONT SLOWLY SINKING SOUTH. WILL KEEP TUESDAY
EVENING DRY...ALTHOUGH THERE MAY BE SOME LINGERING SHOWERS ALONG THE
FRONT ACROSS THE FAR SOUTHERN CWA. LATER SHIFTS WILL HAVE TO WATCH
THIS.

DRIER AND COOLER AIR POURS IN FOR TUESDAY NIGHT AND WEDNESDAY AS
AMPLIFYING H5 FLOW BRINGS NORTHERLY FLOW AND CRASHING THICKNESSES TO
THE GREAT LAKES REGION. THE GFS HAS BEEN ADVERTISING THE COOLDOWN
FOR SEVERAL DAYS AND THE ETA IS ON BOARD. THERE HAS BEEN AN ISSUE
WITH THE ETA AND GFS BLOWING UP A QPF BULLSEYE THAT SKIRTS OUR
SOUTHERN CWA AS A VORT CENTER MOVES ALONG THE BAROCLINIC ZONE SOUTH
OF LOWER MICHIGAN LATE TUESDAY NIGHT INTO WEDNESDAY. WILL LEAVE
WEDNESDAY DRY FOR NOW AS THERE IS STILL QUITE A BIT OF UNCERTAINTY
WITH THE TRACK AND INTENSITY OF THIS FEATURE.

.LONG TERM...
MEDIUM RANGE MODELS SHOW THE CURRENT ZONAL FLOW TRANSITIONING TO A
DEEP TROUGH OVER THE EASTERN LAKES AND NORTHEAST US BY SATURDAY. RUN
TO RUN CONSISTENCY HAS BEEN PRETTY GOOD WITH THIS FEATURE. ON THE
SFC HIGH PRESSURE EXTENDING FROM SOUTHERN ONTARIO INTO WISCONSIN
WILL SLOWLY DRIFT EAST THROUGH THE PERIOD. WELL SEE A NORTH FLOW
FROM THURSDAY NIGHT THROUGH SATURDAY NIGHT BEFORE THE HIGH MOVES TO
OHIO AND WINDS OVER THE CWA VEER TO THE SOUTH. GFS SHOWS H85 TEMPS
FALLING TO AROUND 4C BY SATURDAY MORNING ACROSS THE EASTERN
CWA...BUT GFS HAS BEEN TOO COOL IN SIMILAR SITUATIONS THIS
SUMMER...ALTHOUGH THE TREND IS PROBABLY OK.

BY MONDAY THE GFS SHOWS ANOTHER FRONT MOVING TOWARD MICHIGAN
EXTENDING FROM JAMES BAY SOUTHWEST TO THE CENTRAL PLAINS. WITH SOUTH
FLOW AHEAD OF THE FRONT AND MOISTURE RETURN INCREASING THROUGH THE
PERIOD...TSRA COULD AGAIN BE A PLAYER LATE IN THE DAY. WELL LEAVE
OUT FOR NOW AS THE FRONT SHOULD STILL BE FAR ENOUGH TO
THE NORTHWEST.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...SEVERE THUNDERSTORM WATCH IN
EFFECT ENTIRE FORECAST AREA THROUGH 7 PM EDT.

&&

OSTUNO 93

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1010 AM EDT MON AUG 2 2004

LMZ843>849-MIZ037>040-043>046-050>052-056>059-064>067-071>073-031004-
ALLEGAN-BARRY-CALHOUN-CLARE-CLINTON-EATON-GRATIOT-INGHAM-IONIA-
ISABELLA-KALAMAZOO-KENT-LAKE-MASON-MECOSTA-MONTCALM-MUSKEGON-NEWAYGO-
OCEANA-OSCEOLA-OTTAWA-VAN BUREN-
NEW BUFFALO TO MANISTEE, MI
1010 AM EDT MON AUG 2 2004

.DAY ONE...TODAY AND TONIGHT
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
EVENING. SCATTERED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON...AND A
LINE OF THUNDERSTORMS MAY MOVE ACROSS LAKE MICHIGAN THIS AFTERNOON
AND ARRIVE IN SOUTHWEST LOWER MICHIGAN BY LATE AFTERNOON OR EARLY
EVENING. THE MAIN THREAT WITH THESE STORMS WILL BE WINDS OF 60 MPH
AND HAIL TO ONE INCH IN DIAMETER. HEAVY RAIN AND FREQUENT CLOUD TO
GROUND LIGHTNING ARE ALSO POSSIBLE FROM THESE STORMS. THE AVERAGE
STORM MOTION WILL BE EAST AT 40 MPH.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THUNDERSTORMS ARE POSSIBLE MAINLY SOUTH OF INTERSTATE 96 ON TUESDAY
AS A COLD FRONT SLIPS SOUTH.  SEVERE WEATHER IS NOT FORECASTED
WITH THESE STORMS.  COOLER AND MORE STABLE AIR WILL FILTER IN BEHIND
THIS FRONT FOR THE REMAINDER OF THE WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATE THIS AFTERNOON OR THIS EVENING.

OSTUNO

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
212 PM EDT MON AUG 2 2004

MIZ037>040-043>046-050>052-056>059-064>067-071>074-022300-
ALLEGAN-BARRY-CALHOUN-CLARE-CLINTON-EATON-GRATIOT-INGHAM-IONIA-
ISABELLA-JACKSON-KALAMAZOO-KENT-LAKE-MASON-MECOSTA-MONTCALM-MUSKEGON-
NEWAYGO-OCEANA-OSCEOLA-OTTAWA-VAN BUREN-
212 PM EDT MON AUG 2 2004

THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH
FOR ALL OF SOUTHWEST LOWER MICHIGAN EFFECTIVE UNTIL 700 PM EDT
MONDAY EVENING. THIS WATCH INCLUDES THE FOLLOWING COUNTIES

IN WEST CENTRAL MICHIGAN
     MASON...LAKE...OCEANA...NEWAYGO AND MUSKEGON

IN CENTRAL MICHIGAN
     OSCEOLA...CLARE...ISABELLA...MECOSTA...MONTCALM AND GRATIOT

IN SOUTHWEST MICHIGAN
     KENT...ALLEGAN...BARRY...KALAMAZOO...VAN BUREN AND OTTAWA

IN SOUTH CENTRAL MICHIGAN
     IONIA...CLINTON...INGHAM...EATON...JACKSON AND CALHOUN

THIS WATCH INCLUDES THE ADJOINING COASTAL WATERS OF AFFECTED
LAKESHORE COUNTIES.

RG

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
343 PM EDT MON AUG 02 2004

..TIME...   ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE...   ....MAG....     ..COUNTY LOCATION...ST.. ...SOURCE....
            ..REMARKS..

0336 PM     HAIL             4 E GRAND HAVEN         43.06N 86.14W
08/02/2004  0.75 INCH        OTTAWA             MI   LAW ENFORCEMENT

&&

EJO

PRELIMINARY LOCAL STORM REPORT ... CORRECTION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
404 PM EDT MON AUG 02 2004

..TIME...   ...EVENT...     ...CITY LOCATION...      ...LAT.LON...
..DATE...   ....MAG....     ..COUNTY LOCATION...ST.. ...SOURCE....
            ..REMARKS..

0336 PM     HAIL             4 E GRAND HAVEN         43.06N 86.14W
08/02/2004  0.75 INCH        OTTAWA             MI   LAW ENFORCEMENT

0356 PM     TSTM WND DMG     LILLEY                  43.77N 85.85W
08/02/2004                   NEWAYGO            MI   FIRE DEPT/RESCUE

            TREE DOWN. WIND ESTIMATED AT 70 MPH.

&&

EJO