Severe Thunderstorm Warning 11, NWS Grand Rapids, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
335 PM EDT SUN MAY 9 2004

.SHORT TERM...
PATTERN IS NOT EXPECTED TO CHANGE MUCH THROUGH THE SHORT TERM...WITH
MAINLY ZONAL FLOW IN PLACE ALOFT...AND A MEANDERING BOUNDARY NEARBY
AT THE SURFACE. FORECAST ISSUES REVOLVE AROUND CONVECTION...AND THE
THREAT FOR SEVERE. THE FORECAST AREA IS IN THE DAY ONE AND TWO
OUTLOOKS AT THIS POINT. WILL NOT BE MAKING MANY CHANGES TO THE GOING
FORECAST. THE ETA AND THE GFS ARE SIMILAR WITH THE MAIN FEATURES.

TONIGHT...WILL CARRY LIKELY WORDING FOR SHOWERS AND THUNDERSTORMS
GIVEN THE INSTABILITY THAT IS IN PLACE AND THE WARM FRONT LIFTING
THROUGH THE AREA. MESOSCALE CONVECTIVE VORT MOVING EASTWARD FROM
WISCONSIN WILL ALSO ENHANCE CONVECTION. SEVERE THREAT IS DEFINITELY
THERE...WITH LARGE HAIL AND HEAVY RAIN BEING THE MAIN THREATS.
STRONG CORES ALOFT COULD ALSO LEAD TO WIND DAMAGE VIA WET
MICROBURSTS. IN ADDITION...AN ISOLATED TORNADO IS NOT OUT OF THE
QUESTION WITH 0-1KM SR HELICITY VALUES IN EXCESS OF 200 M2/S2 ALONG
AND NORTH OF THE WARM FRONT. FLOODING THREAT CONTINUES AS STORMS
WILL LIKELY PERSIST OVER AREAS THAT HAVE ALREADY SEEN HEAVY RAIN IN
THE LAST COUPLE DAYS.

WILL CARRY LIKELY WORDING INTO MONDAY...AS UPSTREAM CONVECTION FROM
OVERNIGHT SHOULD BE MOVING INTO THE FORECAST AREA. IN
ADDITION...THE COLD FRONT WILL BE DROPPING INTO THE AREA DURING THE
AFTERNOON. SEVERE THREAT CONTINUES...ESPECIALLY IF WE CAN CLEAR
THINGS OUT A BIT AND DESTABILIZE AHEAD OF THE COLD FRONT.

MONDAY NIGHT...THE FRONT WILL DROP SOUTHWARD TOWARD THE
MICHIGAN/INDIANA BORDER AND BECOME STATIONARY. WITH THE 850MB WARM
FRONT STILL DIRECTLY OVERHEAD WILL CARRY CHANCE POPS THROUGH THE
NIGHT...WITH LIKELY MENTIONED IN THE EVENING SOUTH.

TUESDAY...THE FRONT LIFTS BACK NORTH THROUGH THE FORECAST AREA AS A
WARM FRONT AND WILL NEED TO MAINTAIN A CHANCE OF SHOWERS AND
THUNDERSTORMS. ITS BEGINNING TO SOUND LIKE A BROKEN RECORD. FLOODING
THREAT WILL MOST DEFINITELY CONTINUE GIVEN A WARM AND MOIST AIRMASS
IN PLACE.

TUESDAY NIGHT AND WEDNESDAY FEEL WILL WE NEED TO KEEP A MENTION OF
CHANCE POPS AS WELL. DEEP SOUTHWEST FLOW AND BOUNDARIES NORTH AND
WEST OF THE AREA MAKE THE CHANCES IN THIS TIME FRAME A LITTLE
SMALLER...BUT FEEL A 30 POP IS WARRANTED.

WON/T STRAY FAR FROM GUIDANCE VALUES FOR TEMPS.

.LONG TERM...
TREND OF GFS IS TOWARD ECMWF WHICH THAT BEING TRUE... WOULD LEAD TO
A HIGHER AMPLITUDE SOLUTION FOR LATER IN THE WEEK. THUS I SLOWED
DOWN THE FRONT FRIDAY AND DO NOT HAVE IT COMING THROUGH TILL
SATURDAY MORNING. THAT WOULD LEAD TO A MUCH WARMER FRIDAY AND
SATURDAY AND WARMER LOWS FRIDAY NIGHT. ALSO...GIVEN 1000/850MB
THICKNESS PATTERN...HIGHS SHOULD REACH 80+ THURSDAY AND FRIDAY. I
DID PUSH THE HIGHS TO 80 THURSDAY... ONLY INTO THE MID 70S FOR
FRIDAY AND NEAR 70 SATURDAY.  IF THAT GFS TREND CONTINUES THOSE WILL
NOT BE WARM ENOUGH. THIS WOULD RESULT IN THE BEST CHANCE FOR
THUNDERSTORMS BEING FRIDAY NIGHT ACTUALLY.

&&

.GRR...WATCHES/WARNINGS/ADVISORIES...FLOOD WARNING IN EFFECT THROUGH
THIS EVENING FOR NEWAYGO COUNTY.

&&

DUKE WDM

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
149 PM EDT SUN MAY 9 2004

MIZ037>040-043>046-050>052-056>059-064>067-071>074-101000-
ALLEGAN-BARRY-CALHOUN-CLARE-CLINTON-EATON-GRATIOT-INGHAM-IONIA-
ISABELLA-JACKSON-KALAMAZOO-KENT-LAKE-MASON-MECOSTA-MONTCALM-MUSKEGON-
NEWAYGO-OCEANA-OSCEOLA-OTTAWA-VAN BUREN-
149 PM EDT SUN MAY 9 2004

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

.DAY ONE...TODAY AND TONIGHT

THE ENTIRE AREA HAS BEEN PLACED IN A SLIGHT RISK FOR SEVERE
THUNDERSTORMS THIS AFTERNOON AND TONIGHT BY THE STORM PREDICTION
CENTER. A WARM FRONT LIFTING NORTH THROUGH THE AREA WILL BECOME A
FOCUS FOR STORMS...WITH THE POTENTIAL FOR STORMS TO BECOME SEVERE.

A COUPLE OF ROUNDS OF THUNDERSTORMS ARE EXPECTED...ONE LATE THIS
AFTERNOON AND EVENING...AND ANOTHER LATE TONIGHT. THE STORMS THIS
AFTERNOON AND EVENING WILL BE CAPABLE OF PRODUCING LARGE HAIL TO
AROUND ONE INCH IN DIAMETER...WIND GUSTS TO 60 MPH...CLOUD TO GROUND
LIGHTNING STRIKES...HEAVY RAIN AND THE POTENTIAL FOR AN ISOLATED
TORNADO.

THE MAIN THREATS FROM STORMS OVERNIGHT WILL BE HEAVY RAIN AND STRONG
DAMAGING WINDS.

GIVEN THE AMOUNT OF RAIN ACROSS PORTIONS OF CENTRAL LOWER
MICHIGAN...IN EXCESS OF THREE INCHES OVER WEST CENTRAL LOWER
MICHIGAN IN THE LAST COUPLE OF DAYS...FLOODING IS STILL A MAJOR
CONCERN THIS AFTERNOON AND TONIGHT.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

A SLIGHT RISK OF SEVERE WEATHER EXISTS FOR ALL OF SOUTHWEST MICHIGAN
ON MONDAY AND MONDAY EVENING AS A COLD FRONT APPROACHES FROM THE
NORTHWEST. ADDITIONAL HEAVY RAINFALL AND FLOODING WILL BE POSSIBLE
AS WELL.

MORE SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TUESDAY
THROUGH FRIDAY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS EXPECTED THIS AFTERNOON AND EVENING...AND
POTENTIALLY AGAIN OVERNIGHT.

MEADE DUKE

MIZ037>040-043>046-050>052-056>059-064>067-071>074-100000-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
206 PM EDT SUN MAY 9 2004

THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH
FOR PORTIONS OF THE SOUTHWEST QUARTER OF LOWER MICHIGAN EFFECTIVE
UNTIL 800 PM EDT SUNDAY 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 THE AFFECTED
LAKESHORE COUNTIES.

JK