Severe Thunderstorm Warning 65, NWS Grand Rapids, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
333 PM EDT TUE SEP 10 2002

THE 12Z AVN INITIALIZED BETTER THAN THE OTHER MODELS...ESPECIALLY
WITH THE 850 MB TEMPERATURES.  IT ALSO SEEMS MORE REASONABLE
IN HOLDING ONTO THE STRENGTH OF THE SHORTWAVE TRACKING THROUGH THE
GREAT LAKES REGION THIS EVENING.  WILL BE GENERALLY GOING WITH THE
AVN SOLUTION.

THE MAIN WEATHER CONCERNS WITH THIS FORECAST DEAL WITH THE SEVERE
WEATHER THREAT THIS EVENING...WINDS OVER LAKE MICHIGAN TONIGHT AND
TEMPERATURES THROUGH THE PERIOD.

VERY UNSTABLE ACROSS THE REGION AT THIS TIME.  VALUES ARE LOWER THAN
MINUS 6 ACROSS MUCH OF THE AREA.  LITTLE IN THE WAY OF A CAP AROUND.
ONE BOUNDARY IS PUSHING SLOWLY SOUTHEAST FROM NEAR
CLARE...SOUTHWESTWARD TO NEAR MUSKEGON.  THE STORMS NEAR HARRISON
HAVE BEEN INCREASING AND DEVELOPING SLOWLY SOUTHWESTWARD ALONG THIS
BOUNDARY.   AM EXPECTING THE STORMS TO CONTINUE TO INCREASE ALONG
THIS BOUNDARY...AS IT PUSHES SOUTHEASTWARD THROUGH THE REGION.  THE
STORM PREDICTION CENTER IS MONITORING THE REGION SOUTH AND EAST OF
THIS LINE FOR A POSSIBLE WATCH.  WILL MAINTAIN THE CHANCE OF AN
EVENING SHOWER OR THUNDERSTORM FOR ALL ZONES.

THE FRONT SHOULD PUSH SOUTHEAST OF JXN BY MIDNIGHT.  STRONG NORTHERLY
GRADIENT MOVES IN.  LOOKING AT LAKE SUPERIOR BUOYS...WINDS HAVE BEEN
GUSTING INTO THE MID 30S WITH COLD AIR ADVECTION.  AM EXPECTING SOME
LARGER WAVES TO DEVELOP OVER THE NEARSHORE WATERS ON NORTHERLY WINDS
GUSTING TO NEAR 30 KNOTS.

MUCH COOLER AND DRIER AIR MOVES IN FOR THE REMAINDER OF THE PERIOD.
TEMPERATURES WILL FALL TO MORE SEASONABLE LEVELS.   NOTICED THE
ETA ACTUALLY DRIES THE SURFACE DEWPOINTS INTO THE 30S SOUTH OF JXN
FOR THU NIGHT.  WILL GO LOWER THAN MOS NUMBERS FOR THU NIGHT...
OTHERWISE THE VALUES LOOK FAIRLY GOOD.

MJS

EXTENDED FORECAST DISCUSSION...
MEDIUM RANGE MODELS ALL INDICATE THAT AN AMPLIFYING SHORTWAVE TROUGH
WILL SWING INTO THE GREAT LAKES REGION OVER THE WEEKEND.  MRF AND
ECMWF DIFFER A BIT ON THE TIMING OF THE PASSAGE OF THE UPPER LEVEL
TROUGH.  AVN ENSEMBLES ALSO INDICATE SOME SPREAD WITH RESPECT TO
TIMING AND OVERALL PREFER A LITTLE SLOWER TIMING GIVING THE
AMPLIFYING NATURE OF THE TROUGH.  SHOULD HAVE GOOD MOISTURE RETURN
AHEAD OF THE FRONT AND THE MODELS DEPICT A PRETTY VIGOROUS BOUNDARY
AS IT SWEEPS INTO THE GREAT LAKES. GIVEN THE UNCERTAINTY WITH THE
TIMING OF THE UPPER TROUGH PASSAGE WILL CONTINUE PRECIPITATION
CHANCES SATURDAY INTO SUNDAY.  RELATIVE STRONG AREA OF HIGH PRESSURE
WILL BUILD INTO THE REGION BEHIND THE FRONT WITH SOLID COLD
ADVECTION.  WILL KEEP RELATIVELY COOL AND DRY FORECAST BEHIND
THE TROUGH INTO THE EARLY PORTION OF NEXT WEEK.

GRAHAM

.GRR...NONE.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND RAPIDS, MI
519 PM EDT TUE SEP 10 2002

TIME(EDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0430 PM    2 S LANSING               MI   WIND DAMAGE
09/10/02   INGHAM                         SEVERAL TREES DOWN IN THE
                                          SOUTH SIDE OF LANSING

BDM MJS