Damaging Winds in Michigan, June 19, 2001

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
812 PM EDT TUE JUN 19 2001

...UPDATED FOR LESS CLOUDS AND PRECIPITATION OVERNIGHT...

LATEST VIS SATELLITE IMAGE SHOWS MOSTLY CLEAR SKIES OVER MOST OF THE
GRR CWA AT 740 PM THIS EVENING. THE QUESTION IS WHAT HAPPENS TO THE
TWO AREAS OF PRECIPITATION... ONE SOUTH AND THE OTHER WEST OF OUR
CWA THIS EVENING?  ONE THING FOR SURE... IT WILL STAY MOSTLY CLEAR
FOR A HOUR OR TWO OVER MOST OF THE CWA (EXCEPT THE NW CORNER AND
NEAR JXN).

THE FIRST AREA OF CONCERN IS THE THUNDERSTORMS OVER NE IN AND NW
OH ARE ALONG THE COLD FRONT AND THAT IS SOUTH OF THE GRR CWA AT 740
PM.  SOME OF THE THUNDERSTORMS ARE BEHIND THE FRONT AND THOSE COULD
CLIP THE JXN AREA THIS EVENING SO I DID KEEP ISOLATED THUNDERSTORMS
IN JACKSON AND CALHOUN COUNTIES FOR THIS EVENING.  OTHERWISE I
BELIEVE THE MOVEMENT OF THE FRONT WILL KEEP THE REST OF THE CWA SAFE
FROM THESE STORMS.  IT WILL HAVE TO BE WATCHED THOUGH SINCE EVEN AT
700 PM THE LI'S WERE STILL NEAR -6C OVER JXN AND CAPES OVER 2000
J/KG.

THE NEXT AREA OF PRECIPITATION IS OVER OVER SRN WI...IL...IA... AND
MO.  THAT IS ASSOCIATED WITH THE ENTRANCE REGION OF A 130 KNOT JET
THAT IS NORTHEAST OF LK SUPERIOR IN ONTARIO.  MOST OF THE ENERGY
WITH THAT WAVE STAYS WELL SOUTH OF THE GRR CWA OVERNIGHT. THE RUC
SHOWS THE 850 TO 700 MEAN RH STAYS BELOW 50 PCT TONIGHT OVER ALMOST
ALL OF THE GRR CWA. WITH THAT MUCH DRY AIR... EVEN THOUGH THERE IS
MOIST ABOVE 700 MB AND THERE IS DECENT 300 TO 700 MB QVEC
CONVERGENCE RELATED TO THE PASSING OF THE MID LEVEL WAVE... IT IS
HARD TO BELIEVE MUCH MOISTURE WOULD REACH THE GROUND.  THERE ARE A
FEW SHOWERS NEAR CHI... BUT THOSE DEVELOPED AS THEY MOVED ACROSS THE
LAKE BREEZE BOUNDARY.  THEY WILL LIKELY DISSIPATE BEFORE REACHING
THE LAKE MICHIGAN SHORE LINE. SO MOSTLY THE LAYERED MID AND HIGH
CLOUDS OVER CNTRL LWR MI AND WI WILL BE WHAT MOVE ACROSS THE GRR CWA
OVERNIGHT WILL LITTLE IN THE WAY OF PRECIPITATION.

SO... BOTTOM LINE IS I UPDATE TO CONSIDERABLE CLOUDINESS NORTH 1/3
OF THE CWA OVERNIGHT.  I HAVE MOSTLY CLEAR BECOMING MOSTLY CLOUDY
OVER CENTRAL AREAS AND OVER BTHE SOUTH 1/3 I HAVE PUT A CHC OF
SHOWERS OVERNIGHT (KEPT ISOLATED THUNDERSTORMS NEAR JXN THIS
EVENING).

.GRR...NONE.

WDM