Severe Thunderstorm Warning 80, NWS Grand Rapids, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
323 PM EDT FRI AUG 24 2007

LATEST UPDATE...LONG TERM AND AVIATION...

.SYNOPSIS...(345 AM EDT FRI AUG 24 2007)
STRONG TO SEVERE THUNDERSTORMS MAY REDEVELOP THIS AFTERNOON AND
ESPECIALLY FOR TONIGHT AS INTENSIFYING LOW PRESSURE MOVES NORTHEAST
ALONG THE COLD FRONT COMING THROUGH OUR AREA. DAMAGING WIND GUSTS
WILL BE THE PRIMARY SEVERE WEATHER THREAT.  AN ISOLATED TORNADO
CANNOT BE RULED OUT THIS AFTERNOON AND EVENING. HIGH PRESSURE WILL
BUILD IN THIS WEEKEND ALLOWING FOR TRANQUIL WEATHER TO FINALLY
RETURN TO OUR AREA.

&&

.SHORT TERM... (1239 PM EDT FRI AUG 24 2007)
CONVECTIVE MORPHOLOGY QUITE A BIT MORE MUDDY AS COMPARED TO
YESTERDAY. FEATURE OF NOTE AT THE SURFACE IS A QUASI STATIONARY
BOUNDARY EXTENDING FROM FAR NORTHERN LOWER MICHIGAN SOUTHWEST INTO
IOWA. SOUTH OF THIS BOUNDARY OUTFLOW BOUNDARIES FROM STORMS OF THE
LAST 24 HOURS HAVE PROPAGATED WELL SOUTH INTO MISSOURI...SOUTHERN
ILLINOIS AND CENTRAL INDIANA. QUITE A BIT OF CLOUD COVER LIES
BETWEEN THESE TWO SURFACE FEATURES...INCLUDING OVER SOUTHERN LOWER
MICHIGAN. ALOFT...MAIN FEATURE TO KEY ON IS SHORTWAVE HEADING OUT OF
KANSAS INTO MISSOURI. THIS FEATURE HAS STORMS ASSOCIATED WITH IT IN
CENTRAL AND SOUTHERN MISSOURI AT THIS TIME. THIS SHORTWAVE ALOFT IS
EXPECTED TO MOVE NORTHEAST AND BE IN NORTHERN INDIANA/SOUTHWEST
LOWER MICHIGAN THIS EVENING.

FEEL THAT WE HAVE A CHANCE FOR STORMS THIS AFTERNOON GIVEN MANY WEAK
IMPULSES IN THE FLOW. BUILDING INSTABILITY IS TAKING PLACE ALTHOUGH
IT IS NO WHERE NEAR AS GREAT AS YESTERDAY AFTERNOON. THE CLOUD COVER
IS HINDERING THIS AND MAY CONTINUE TO DO SO THROUGH THE AFTERNOON.
SO...SMALL CLUSTERS OF STORMS MAY BE POSSIBLE THROUGH THE AFTERNOON.
FEEL THE MAIN SHOW IN THE NEXT 12 HOURS THOUGH WILL LIKELY BE
ASSOCIATED WITH THE STORMS MOVING NORTHEAST OUT OF MISSOURI. FEEL
THIS WILL PROBABLY CONGEAL INTO A LINE AND MOVE ACROSS ILLINOIS INTO
NORTHERN INDIANA AND POTENTIALLY INTO SOUTHERN LOWER MICHIGAN. BEST
CHANCES FOR STORMS AND SEVERE ARE IN THE MODERATE RISK AREA...WHICH
IN OUR AREA WILL BE SOUTH OF A LINE FROM SAUGATUCK TO LANSING
ROUGHLY. STRONG WINDS REMAIN THE PRIMARY THREAT...BUT HEAVY RAIN AND
AN ISOLATED TORNADO CANNOT BE RULE OUT EITHER GIVEN LARGE SHEAR
VALUES IN THE 0-6KM LAYER...IN EXCESS OF 40 KTS. FEEL THIS LINE OF
STORMS WILL BE LATER INTO THE EVENING AS COMPARED TO LAST
NIGHT...PROBABLY MORE TOWARD 900 PM IF IT EVOLVES AS THOUGHT.

COOLER AND DRIER AIR WILL FINALLY FILTER IN BEHIND THE COLD FRONT
FOR THE WEEKEND AS HIGH PRESSURE BUILDS IN.

&&

.LONG TERM... (323 PM EDT FRI AUG 24 2007)
A RELATIVELY QUIET PERIOD IS EXPECTED. HIGH PRESSURE OVER THE GREAT
LAKES WILL SLOWLY MOVE EAST MONDAY AND ALLOW THE NEXT COLD FRONT TO
DROP SOUTH TUESDAY NIGHT AND WEDNESDAY. WE/LL CONTINUE WITH THE TSRA
DURING THAT TIME FRAME WITH DRY AND MUCH COOLER WX AFTER. H8 TEMPS
FALL TO AROUND +4C BY THE END OF THE WEEK. THAT SHOULD RESULT IN
HIGHS MAINLY IN THE 60S BY FRIDAY.

&&

.AVIATION...(323 PM EDT FRI AUG 24 2007 )
SHOWERS AND THUNDERSTORMS ARE IN THE FORECAST FOR THE NEXT 18 HRS OR
SO. SOME OF THE STORMS MAY TAKE VISIBILITIES DOWN TO A MILE OR
SO...BUT MAINLY FOR THE SRN TAF SITES. IMPROVING CONDTIONS WILL
ARRIVE SAT MORNING AFTER THE COLD FRONT MOVES THROUGH WHEN DRIER AIR
MOVES IN.

&&

.MARINE... (345 AM EDT FRI AUG 24 2007)
SMALL CRAFT ADVISORY WHICH WAS IN EFFECT FOR THE NEARSHORE WATERS OF
LAKE MI FROM HOLLAND TO MANISTEE HAS BEEN CANCELLED EARLY. STORMS
WILL LOCALLY INCREASE WIND AND WAVES TODAY AND TONIGHT AND POSE A
SIGNIFICANT THREAT TO MARINERS.

&&

.HYDROLOGY... (345 AM EDT FRI AUG 24 2007)
AREA RIVERS REMAIN HIGHER THAN NORMAL BUT ARE GENERALLY WELL BELOW
FLOOD STAGE. ADDITIONAL HEAVY RAIN IS EXPECTED THIS AFTERNOON AND
ESPECIALLY TONIGHT. PRECIPITABLE WATER VALUES REMAIN IN EXCESS OF
2.00 INCHES INTO FRIDAY NIGHT SO STORMS SHOULD BE EFFICIENT HEAVY
RAIN PRODUCERS. WILL NEED TO MONITOR RAINFALL AND RIVER LEVELS FOR
POTENTIAL HYDRO ISSUES VERY CLOSELY LATER THIS AFTERNOON AND
TONIGHT.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LM...NONE.

&&

SYNOPSIS:   LAURENS/DUKE
SHORT TERM: DUKE
LONG TERM:  OSTUNO
AVIATION:   OSTUNO
MARINE:     LAURENS
HYDROLOGY:  LAURENS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
155 PM EDT FRI AUG 24 2007

LMZ844>849-MIZ037>040-043>046-050>052-056>059-064>067-071>074-251015-
ST JOSEPH TO SOUTH HAVEN-SOUTH HAVEN TO HOLLAND-
HOLLAND TO GRAND HAVEN-GRAND HAVEN TO WHITEHALL-
WHITEHALL TO PENTWATER-PENTWATER TO MANISTEE-MASON-LAKE-OSCEOLA-
CLARE-OCEANA-NEWAYGO-MECOSTA-ISABELLA-MUSKEGON-MONTCALM-GRATIOT-
OTTAWA-KENT-IONIA-CLINTON-ALLEGAN-BARRY-EATON-INGHAM-VAN BUREN-
KALAMAZOO-CALHOUN-JACKSON-
155 PM EDT FRI AUG 24 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST LOWER
MICHIGAN.

.DAY ONE...THIS AFTERNOON AND TONIGHT
SCATTERED THUNDERSTORMS WILL BE POSSIBLE THIS AFTERNOON...SOME OF
WHICH MAY BE SEVERE...WITH DAMAGING WINDS AND HEAVY RAIN BEING THE
MAIN THREATS.

A MORE CONCENTRATED AREA OF SEVERE WEATHER IS POSSIBLE ACROSS
SOUTHERN LOWER MICHIGAN THIS EVENING AS STORMS MOVE INTO THE AREA
FROM THE SOUTHWEST. AREAS ALONG AND SOUTH OF A LINE FROM MUSKEGON TO
MOUNT PLEASANT HAVE A THREAT FOR SEVERE STORMS...WITH THE INTERSTATE
94 CORRIDOR MOST AT RISK. DAMAGING WINDS AGAIN WILL BE THE MAIN
THREAT WITH WIND GUSTS TO 60 MPH POSSIBLE. ISOLATED LARGE HAIL AND
EVEN A TORNADO ARE POSSIBLE...BUT THE STRONG WIND THREAT WILL BE THE
MAIN ISSUE. THUNDERSTORM MOVEMENT WILL BE TO THE NORTHEAST AT 30 TO
40 MPH.

AS THUNDERSTORMS CONTINUE TO MOVE OVER THE SAME AREAS LOCALIZED
FLOODING AND PONDING OF WATER IS A DISTINCT POSSIBILITY BOTH THIS
AFTERNOON AND TONIGHT. SOME LOCATIONS WILL LIKELY SEE OVER AN INCH
OF RAIN...WITH ISOLATED REPORTS IN EXCESS OF TWO INCHES POSSIBLE.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THUNDERSTORMS ARE POSSIBLE ALONG A COLD FRONT ON TUESDAY AFTERNOON
AND INTO WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON OR EVENING.

OSTUNO DUKE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
357 PM EDT FRI AUG 24 2007

MIZ058-059-065>067-242100-
BARRY-CLINTON-EATON-INGHAM-IONIA-
357 PM EDT FRI AUG 24 2007

...SPECIAL WEATHER STATEMENT...

AT 354 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM 13 MILES NORTH OF
PORTLAND TO 15 MILES WEST OF CHARLOTTE...MOVING EAST AT 35 MPH.

WINDS GREATER THAN 40 MPH...FREQUENT CLOUD TO GROUND LIGHTNING...ARE
POSSIBLE WITH THESE STORMS.

LOCATIONS IN OR NEAR THE PATH INCLUDE...GRAND LEDGE...CHARLOTTE...ST.
JOHNS...POTTERVILLE...EDGEMONT PARK...DEWITT...ELSIE AND LANSING.

GUSTY WINDS MAY CAUSE SMALL OBJECTS SUCH AS TRASH BINS TO BLOW
AROUND. STAY AWAY FROM HIGH OBJECTS OUTDOORS SUCH AS TREES.

SEEK SHELTER IN A STURDY STRUCTURE UNTIL THESE STORMS HAVE PASSED.

LAT...LON 4313 8478 4247 8516 4246 8454 4312 8435

93

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
415 PM EDT FRI AUG 24 2007

MIZ067-073-074-242045-
CALHOUN-INGHAM-JACKSON-
415 PM EDT FRI AUG 24 2007

...SPECIAL WEATHER STATEMENT...

AT 411 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR MARSHALL...MOVING EAST AT 45 MPH.

WINDS GREATER THAN 40 MPH...FREQUENT CLOUD TO GROUND LIGHTNING...ARE
POSSIBLE WITH THIS STORM.

LOCATIONS IN OR NEAR THE PATH INCLUDE...ALBION.

GUSTY WINDS MAY CAUSE SMALL OBJECTS SUCH AS TRASH BINS TO BLOW
AROUND. STAY AWAY FROM HIGH OBJECTS OUTDOORS SUCH AS TREES.

SEEK SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS PASSED.

LAT...LON 4233 8505 4215 8500 4217 8413 4251 8417

93