Severe Thunderstorm Warning 40, NWS Grand Rapids, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
300 PM EDT THU MAY 18 2000

...CONTINUED FLOOD WARNING FOR CENTRAL 1/3 OF CWA TILL 600 AM FRI...

BASED ON A COMBINATION OF THE SFC OBS...COMPOSITE RADAR LOOPS...AND
THE SATELLITE LOOPS OF THE IR AND WATER VAPOR... THE RUN/AVN ARE
DOING THE BEST WITH THE AREA OF CONVECTION NORTH OF THE STATIONARY
FRONT NEAR THE MICHIGAN/INDIANA BORDER.  THE VERTICALLY STACKED SFC
TO UPPER LOW OVER IOWA WILL HOLD TOGETHER LONGER THAN FCST BY
ETA/NGM AND MORE LIKE RUC/AVN. THIS WILL ALLOW MID LEVEL WAA/850
THTE CONVERGENCE... AND ISENTROPIC LIFT TO STAY FARTHER NORTH THEN
SUGGEST BY THE ETA/NGM AND MORE LIKE THE AVN/RUC.  IN FACT... THE RUC
SUGGEST INCREASES ISENTROPIC LIFT/850 THTE CONVERGENCE AND JET LIFT
BTW 00Z AND 06Z OVER CNTL LOWER MI.  SINCE CURRENT RADAR/IR TRENDS
SHOW GOOD AREA OF CONVECTION N OF LOW OVER NE IOWA... WILL CONTINUE
SHWRS AND THUNDERSTORM FROM I-96 SOUTH TILL MIDNIGHT.  AFTER THAT
POINT THE BEST UPPER SUPPORT SINKS SOUTH OF CWA BUT NOT BY MUCH. SO
WILL CONTINUED SHOWERS AND THUNDERSTORMS INTERSTATE 94 AREA
OVERNIGHT BUT HAVE ONLY SHOWERS I-94 TO I-96. WILL HAVE ONLY SCT
SHWRS THIS EVENING... NORTH OF THAT TONIGHT AS DRY AIR SLOWLY MOVES
IN FROM THE NORTH.  WITH THE 4 TO 6 INCHES OF RAIN THAT HAS FALLEN
OVER THE NRN PART OF THE FLOOD WARNING AREA ALREADY AND POSSIBLY
ANOTHER INCH OF RAIN BY 06Z OVER THAT AREA... WILL CONTINUE THE
FLOOD WARNING OVERNIGHT FOR INTERSTATE 94 TO 96 AREA. WHILE IT IS
POSSIBLE FOR SOUTHERN TIER TO GET FLOODING... IT HAS BEEN FAIRLY DRY
THERE SO FAR... AND DO NOT EXPECT THE 3 TO 5 INCH RAINS OF LAST
NIGHT DOWN THERE TONIGHT... THE HEAVIEST RAIN TONIGHT WILL BE SOUTH
OF MI CLOSER TO THE SFC FRONT.

ON FRIDAY... DRY AIR MOVES IN FROM THE NORTH SLOWLY BUT SURELY AS
THE SYSTEM CONTINUES TO SHEAR OUT. WILL FCST GRADUAL CLEARING FROM N
TO SOUTH... ENDING THE SHOWERS OVER THE SOUTH IN THE AFTERNOON.

FRIDAY NIGHT... PARTLY CLOUDY SOUTH AND MOSTLY CLEAR NORTH. ENOUGH
COOL DRY AIR FOR PATCHY FROST NRN CWA.

SATURDAY...  HIGH PRESSURE RIDGE MOVES THROUGH SO IT WILL BE MOSTLY
CLEAR BUT STILL COOL.

EXTENDED FORECAST... UPPER LOW OVER ARIZONA THIS AFTERNOON WILL FORM
A WAVE ON THE FRONT NEAR ARK ON SAT. THIS COULD COME NORTH TOWARD LWR
MI ON SUNDAY. THAT WILL DEPEND ON JUST HOW MUCH DIGGING THERE IS WITH
NRN STREAM WAVE DIVING INTO NE2 MT.  WILL PLAY THIS AS A MISS FOR NOW
AND LEAVE SUNDAY DRY.  THAT SYSTEM WILL BRING MORE SHWRS/TSTMS TO MI
BY MONDAY.

ZONE FCST AROUND 400 PM.

.GRR...NONE.

WDM

MIZ037>040-043>046-050>052-056>059-064>067-071>074-191000-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1215 PM EDT THU MAY 18 2000

...HAZARDOUS WEATHER POTENTIAL STATEMENT FOR THE SOUTHWEST QUARTER
OF LOWER MICHIGAN FOR THIS AFTERNOON AND TONIGHT...

DISPATCHERS PLEASE PASS THIS INFORMATION ALONG TO YOUR EMERGENCY
MANAGERS.

HAZARDS...RISES IN RIVERS...CREEKS AND STREAMS WILL CONTINUE IN
PORTIONS OF SOUTHWEST MICHIGAN THIS AFTERNOON AND TONIGHT. THIS IS
THE RESULT OF THE COMBINATION OF LAST NIGHTS HEAVY RAINFALL
NORTH OF INTERSTATE 94 AND THE EXPECTED HEAVY RAINFALL THIS
AFTERNOON FROM STRONG THUNDERSTORMS.  STREET FLOODING AND PONDING OF
WATER IN LOW AREAS HAS ALREADY BEEN REPORTED AND MORE CAN BE
EXPECTED THIS AFTERNOON.  ADDITIONAL SHOWERS AND THUNDERSTORMS THIS
AFTERNOON AND TONIGHT WILL ONLY AGGRAVATE THE FLOODING PROBLEMS.
REFER TO THE LATEST FLOOD WARNINGS AND STATEMENTS FROM THE GRAND
RAPIDS NWS FOR MORE SPECIFIC DETAILS.

A SLIGHT RISK OF SEVERE THUNDERSTORMS EXISTS THIS AFTERNOON AND TONIGHT
SOUTH OF A LINE FROM LITTLE SABLE POINT TO ALMA.  THE MAIN THREAT IS
FOR HAIL GREATER THAN 3/4 INCH IN DIAMETER...WINDS OF 60 MPH ARE
ALSO POSSIBLE.  STORM MOVEMENT WILL BE TO THE EAST AT 40 TO 60 MPH.
LITTLE RAINFALL OCCURRED OVERNIGHT... ALONG THE INTERSTATE 94
CORRIDOR... BUT AN INCH OR MORE OF RAIN IS CERTAINLY POSSIBLE IN
THESE AREAS THIS AFTERNOON AND TONIGHT.

DISCUSSION...A STATIONARY FRONT WAS SITUATED OVER THE INTERSTATE 94
AREA AT 1100 AM.  THIS FRONT WILL START MOVING SOUTH AS A COLD
FRONT DURING THE AFTERNOON.  MEANWHILE... A STRONG LOW PRESSURE
SYSTEM MOVING EAST ALONG THE FRONT WILL PUSH MORE WARM MOIST AIR
OVER THE FRONT TOWARD SOUTHERN LOWER MICHIGAN THIS AFTERNOON AND
TONIGHT.  AS TIME GOES ON...WITH THE FRONT MOVING SOUTH AS THE LOW
PRESSURE SYSTEM MOVES ALONG IT... THE AREA OF HEAVY RAINFALL WILL
SHIFT SOUTHWARD.  TONIGHT... THE HEAVIEST RAINFALL WILL BE SOUTH OF
INTERSTATE 94.

SPOTTER ACTIVATION...
SPOTTERS HAVE BEEN ACTIVATED.

WDM

MIZ056>059-064>067-071>074-190015-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
209 PM EDT THU MAY 18 2000

THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH
FOR PORTIONS OF THE SOUTHWEST QUARTER OF LOWER MICHIGAN EFFECTIVE
UNTIL 800 PM EDT THURSDAY EVENING. THIS WATCH INCLUDES THE FOLLOWING
COUNTIES

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

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

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 ORO THE
LOCAL NEWS OUTLETS FOR THE LATEST UPDATES AND POSSIBLE WARNINGS.

NNNN

MIZ056>059-064>067-071>074-190015-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
210 PM EDT THU MAY 18 2000

THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH
FOR PORTIONS OF THE SOUTHWEST QUARTER OF LOWER MICHIGAN EFFECTIVE
UNTIL 800 PM EDT THURSDAY EVENING. THIS WATCH INCLUDES THE FOLLOWING
COUNTIES

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

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

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

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.

NNNN