Tornado Warning 3, NWS Grand Rapids, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1050 AM EDT THU JUL 1 1999

...VARIABLE CLOUDINESS/SCATTERED SHOWERS AND THUNDERSTORMS THIS PM...

FAIRLY STRONG SHTWV AND ASSOC SFC LOW EXITING GRR CWA AS I WRITE
THIS.  SFC LOW NEAR SBN AT 14Z WITH WARM FRNT NEAR MI BORDER.  ALL
OF THIS AT NOSE OF 300 MB JET EXIT REGION.  DURING THE AFTERNOON
THIS WILL MOVE EAST OF GRR CWA AND 15Z 88D SHOWS MAIN PCPN AREA
ALREADY EAST OF US-131.  ARE OF THUNDESTORMS HAS DEVELOPED NEAR WARM
FRONT SOUTH OF LANSING DURING PAST HOUR.  EVEN SO... THIS ACTIVITY
WILL BE EAST OF ENTIRE CWA BY 1-2 PM.

MEANWHILE... YET ANOTHER SHTWV... SPINNING IN THE COOLER AND DRIER
AIR TO OUR WEST IS HEADING TOWARD SW MI FOR LATER THIS AFTERNOON AND
EARLY TONIGHT. 12Z RUC SHOWS THIS SYSTEM WILL REDEVELOP AS IT MOVES
INTO SW MI LATER THIS AFTERNOON.  COMBINATION OF SECOND JET SPEED
MAX WITH DEPARTING SPEED MAX TO CREATE JET COUPLING.  RUC SHOWS GOOD
700 TO 300 MB DPV AND SOME 850 MOISTURE FLUX CONVERGENCE. WHILE 850
TO SFC DWPTS WILL BE SOME WHAT DRIER OVER SW LWR MI THEN AHEAD OF
PRIMARY SYS... WHICH BY 00Z WILL BE EAST OF MI TOTALLY... SHOULD
ALLOW ENOUGH INSTABLITY TO REDEVELOPE THUNDERTSTORMS TOWARD EVENING.
WILL BE SOME PARTIAL CLEARING SRN AND CNTL PART OF CWA BY MID
AFTERNOON AS SUBSIDENCE BETWEEN INCOMING AND OUTGOING SYSTEM ALLOWS
BRIEF BRAKE IN CLOUDS.  ENOUGH TO INCREASE INSTABLITY TOO.

BOTTOM LINE... TO MAKE IT SIMPLE WILL FORECAST VARIABLE CLOUDINESS
THIS AFTERNOON WITH SCATTERED SHOWERS AND THUNDERSTORMS.  LET
NOWCASTS DEAL WITH DETAILS. HIGHS 75 TO 80 SOUTH... MID 70S NORTH.

.GRR...NONE.

WDM

MIZ037>040-043>046-050>052-056>059-064>067-071>074-021200-

HAZARDOUS WEATHER POTENTIAL STATEMENT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1155 AM EDT THU JUL 1 1999

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

DISPATCHERS...PLEASE PASS THIS INFORMATION ALONG TO YOUR EMERGENCY
MANAGERS.

HAZARDS...A SLIGHT CHANCE OF SEVERE THUNDERSTORMS EXISTS LATE THIS
AFTERNOON AND EVENING OVER SOUTHWEST LOWER MICHIGAN. HIGH WINDS TO
70 MPH AND HAIL TO 1 INCH ARE POSSIBLE WITH THESE STORMS.

DISCUSSION...PARTIAL CLEARING DURING THIS AFTERNOON WILL ALLOW THE
ATMOSPHERE TO DESTABIZLE.  A UPPER LEVEL DISTURBANCE WILL CROSS
SOUTHWEST MICHIGAN DURING THE EVENING HOURS.  THE COMBINATION OF THE
UPPER AIR SYSTEM AND THE UNSTABLE ATMOSPHERE DOES ALLOW THE
POTENTIAL FOR AN ISOLATED SEVERE THUNDERSTORM LATER THIS AFTERNOON
INTO THIS EVENING SOUTH OF A LINE FROM WHITEHALL TO ALAMA.  THE
STORMS WILL MOVE TO THE EAST NORTHEAST AROUND 25 MPH.

THE UPPER AIR DISTURBANCE WILL MOVE EAST OVERNIGHT...BRINGING AN END
TO THE THUNDERSTORM ACTIVITY BY MIDNIGHT.

SPOTTER ACTIVATION...SPOTTER ACTIVATION MAY BE REQUIRED LATE THIS
AFTERNOON AND EVENING.

WDM

MIZ037>040-043>046-050>052-056>059-064>067-071>074-021200-

HAZARDOUS WEATHER POTENTIAL STATEMENT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1155 AM EDT THU JUL 1 1999

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

DISPATCHERS...PLEASE PASS THIS INFORMATION ALONG TO YOUR EMERGENCY
MANAGERS.

HAZARDS...A SLIGHT CHANCE OF SEVERE THUNDERSTORMS EXISTS LATE THIS
AFTERNOON AND EVENING OVER SOUTHWEST LOWER MICHIGAN. HIGH WINDS TO
70 MPH AND HAIL TO 1 INCH ARE POSSIBLE WITH THESE STORMS.

DISCUSSION...PARTIAL CLEARING DURING THIS AFTERNOON WILL ALLOW THE
ATMOSPHERE TO DESTABIZLE.  A UPPER LEVEL DISTURBANCE WILL CROSS
SOUTHWEST MICHIGAN DURING THE EVENING HOURS.  THE COMBINATION OF THE
UPPER AIR SYSTEM AND THE UNSTABLE ATMOSPHERE DOES ALLOW THE
POTENTIAL FOR AN ISOLATED SEVERE THUNDERSTORM LATER THIS AFTERNOON
INTO THIS EVENING SOUTH OF A LINE FROM WHITEHALL TO ALAMA.  THE
STORMS WILL MOVE TO THE EAST NORTHEAST AROUND 25 MPH.

THE UPPER AIR DISTURBANCE WILL MOVE EAST OVERNIGHT...BRINGING AN END
TO THE THUNDERSTORM ACTIVITY BY MIDNIGHT.

SPOTTER ACTIVATION...SPOTTER ACTIVATION MAY BE REQUIRED LATE THIS
AFTERNOON AND EVENING.

WDM