Hail and Damaging Winds in Michigan, August 12, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
350 PM EDT MON AUG 12 2002

LATE AFTERNOON SURFACE ANALYSIS SHOWED COLD FRONT PUSHING ACROSS
MN/IA...WITH PLENTY OF WARMTH/MOISTURE/INSTABILITY IN PLACE OUT AHEAD
OF BOUNDARY. FRONT IS FORECAST TO PUSH SLOWLY EAST OVER NEXT TWO
DAYS...CROSSING FORECAST AREA TUE NIGHT. CHANCES FOR CONVECTION
THROUGH WED...ALONG WITH TIMING FRONTAL PASSAGE REPRESENT MAIN
FORECAST CONCERNS.

TONIGHT...COLD FRONT IS FORECAST TO PUSH E INTO CENTRAL WI. THIS...
TOGETHER WITH DEW POINTS NEAR 70F...LI/S AROUND -8...AND REMNANTS OF
WARM FRONT ACROSS THE STRAITS REGION WILL MAKE SCATTERED CONVECTION
A POSSIBILITY MOST ANYWHERE. BEST COVERAGE WILL LIKELY REMAIN NW OF
A HTL-APN LINE.

TUESDAY AND TUESDAY NIGHT...500 MB TROUGH OVER WESTERN GREAT LAKES
WILL CONTINUE TO SLOWLY OPEN AND LIFT NE -- AIDED BY SHARP HEIGHT
FALLS OVER SW CANADA. BEST LOW LEVEL THERMAL CONTRAST ACROSS COLD
FRONT WILL LIFT NE INTO CANADA. THIS...COUPLED WITH FRONT BECOMING
PROGRESSIVELY MORE PARALLEL TO UPPER FLOW...WILL CAUSE BOUNDARY TO
SLOW ITS EASTWARD MOVEMENT (AS SUPPORTED BY ETA RUN TO RUN TRENDS).
BY 00Z WED...FRONT IS FORECAST TO EXTEND FROM SSM TO GRB -- THEN BY
12Z WED FROM APN TO HTL. MODELS ARE IN REASONABLY GOOD AGREEMENT
REGARDING FRONTAL MOVEMENT -- THOUGH IN TYPICAL FASHION THE AVN HAS
OVERDONE CONVECTIVELY ENHANCED WAVE ALONG FRONT. ORGANIZED SW INFLOW
AHEAD OF BOUNDARY -- WITH 20-30 KT 850 MB WINDS -- WILL HELP TO
MAINTAIN A GOOD DEAL OF MOISTURE ACROSS REGION (850 MB THETA-E
RIDGING...PWAT/S AROUND 1.75 IN...AND 850 MB DEW POINTS OF +12-14C).
MOISTURE...APPROACHING FRONT...AND ORGANIZED AREA OF 850/500 MB
Q-VECTOR CONVERGENCE ASSOCIATED WITH APPROACH OF UPPER TROUGH...
WILL KEEP GOOD RISK OF SHOWERS/THUNDERSTORMS GOING.

SEVERE THREAT TUE AND TUE NIGHT WILL HAVE TO BE CLOSELY
MONITORED...AS 35-40 KT 500 MB WINDS ROTATE AROUND UPPER TROUGH --
PLACING FORECAST AREA IN FAVORED RIGHT ENTRANCE REGION OF JET.
SEVERE THREAT WILL LIKELY HINGE ON OUR ABILITY TO DESTABILIZE VIA
INSOLATION. MODEL SOUNDINGS -- ASSUMING 80/69 -- SUPPORT BETTER THAN
2000 J/KG OF CAPE. HOWEVER...CLOUD COVER (CONVECTIVE DEBRIS) COULD
EASILY NEGATE THIS. LASTLY...WIND FIELDS (CORFIDI VECTORS) SUPPORT
POTENTIAL FOR SLOW MOVING STORMS PRODUCING LOCALLY HEAVY RAINFALL.

WEDNESDAY...WEAKENING COLD FRONT IS FORECAST TO EXIT FORECAST AREA
EARLY WED MORNING...WITH DRIER AIR SLOWLY FILTERING IN FROM THE WEST
DURING THE DAY. WILL KEEP RISK OF SHOWERS GOING OVER NE LOWER
THROUGH THE MORNING -- PER GOING FORECAST. HOWEVER...WILL HAVE TO
WATCH FOR PRECIPITATION CHANCES TO LINGER LONGER...ESPECIALLY IF
FRONT SLOWS FURTHER. WILL TREND FORECAST TOWARD PARTLY SUNNY ALL
AREAS BY WED AFTERNOON.

WEDNESDAY NIGHT AND THURSDAY...REMNANTS OF FRONT/TROUGH WILL SLIP
EAST...AS NEXT FRONT BEGINS TO TAKE SHAPE OVER NORTHERN PLAINS. IN
FACT...SW FLOW IS FORECAST TO QUICKLY REESTABLISH ITSELF AHEAD OF
THIS NEXT FRONT IMMEDIATELY WED NIGHT AND THU. MOISTURE...FRONTAL
SUPPORT...AND UPPER DYNAMICS WILL BE LACKING DURING THIS TIMING
HOWEVER...SO A GENERAL PARTLY CLOUDY FORECAST APPEARS IN ORDER WED
NIGHT AND THU.

FRIDAY THROUGH MONDAY...MEDIUM RANGE MODELS ARE IN AGREEMENT THAT
BROAD...LOW AMPLITUDE UPPER TROUGH WILL EVOLVE BY WEEKS END OVER
SOUTH CENTRAL CANADA. NORTHERN PART OF U.S. -- FROM THE NORTHERN
ROCKIES EAST TO UPPER GREAT LAKES -- WILL MARK SOUTHERN EXTENT OF
THIS UPPER TROUGH. A SERIES OF SHORT WAVE TROUGHS ARE FORECAST TO
ROTATE THROUGH TROUGH...WITH RESULTING SURFACE TROUGHING TO PROVIDE
FOCUS FOR CONVECTION. GULF SHOULD BE WIDE OPEN DURING THIS TIME
PERIOD -- WITH AMPLE MOISTURE LIKELY TO BE IN PLACE. MODELS ARE
HAVING A TOUGH TIME NAILING DOWN LOCATION OF INDIVIDUAL SHORT
WAVES...PER EXAMINATION OF MRF/ECMWF/GEM/UKMET...MRF ENSEMBLES...
AND LATEST 12Z AVN. THE OPERATIONAL MRF SUGGESTS THAT FIRST TROUGH
WILL PUSH THROUGH SAT...WITH THE NEXT BY LATE SUN AND MON (THOUGH
MRF IS NOT EXHIBITING MUCH RUN TO RUN CONSISTENCY). AT THIS
TIME...WILL NOT GET TOO PRECISE -- AND SIMPLY INCLUDE A CHANCE FOR
SHOWERS AND STORMS STARTING SAT AND CONTINUING THROUGH MON (THOUGH
THERE COULD BE A BREAK DURING THIS TIME). TEMPERATURES WILL
GENERALLY AVERAGE CLOSE TO SEASONAL NORMALS.

.APX...NONE.

SMITH

MIZ008-015>036-041-042-131200-

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE GAYLORD MI
150 PM EDT MON AUG 12 2002

...SEVERE WEATHER IS POSSIBLE TONIGHT IN EASTERN UPPER AND NORTHERN
LOWER MICHIGAN...

* THREAT AREA....ALL OF EASTERN UPPER MICHIGAN AND NORTHERN LOWER
  MICHIGAN.

* DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGERS IMMEDIATELY.
  SPOTTER ACTIVATION MAY BE NEEDED TONIGHT.

* HAZARDOUS WEATHER THREAT...THUNDERSTORM WIND GUSTS UP TO 60 MPH.

* TIME OF HAZARDOUS WEATHER THREAT...FROM MIDNIGHT TONIGHT THROUGH
  500 AM TUESDAY MORNING.

* FOR INFORMATION REGARDING ONGOING...POSSIBLY HAZARDOUS WEATHER
  CONDITIONS PLEASE REFER TO WWW.CRH.NOAA.GOV/APX/ (ALL LOWER CASE).

IF LATER INFORMATION FURTHER SUPPORTS THIS HAZARDOUS WEATHER THREAT...
APPROPRIATE WATCHES AND/OR WARNINGS WILL BE ISSUED. STAY TUNED TO NOAA
WEATHER RADIO OR YOUR LOCAL MEDIA FOR THE LATEST WEATHER INFORMATION.

JZ/CJC/SWR