Marine Thunderstorm Winds in Lake St. Clair, July 22, 2002

SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
320 PM EDT SUN JUL 21 2002

...SEVERE WEATHER THREAT TODAY...

CONVECTION CONTINUES TO SLOWLY DIMINISH ACROSS WI AND THE DEBRIS
CLOUD WAS STRUGGLING TO MAKE IT INTO THE CWA. SOME ISOLATED
THUNDERSTORMS DEVELOPED ACROSS SOUTHWEST LOWER MI...NORTHWEST
INDIANA...AND SOUTHERN LAKE MI EARLY...BUT JUST SOME AC LEFT FROM
THAT AT 07Z. LOCAL CONVECTIVE INITIATION MODEL PICKED UP ON THE
ISOLATED CONVECTION AND DID NOT HAVE ANYTHING NEW DEVELOPING AFTER
07Z. THEREFORE...EXPECT THE REST OF THE MORNING TO BE DRY.

MODELS IN DECENT AGREEMENT WITH THE OVERALL PATTERN...AND PASSAGE OF
THE COLD FRONT. THE ETA IS THE QUICKEST WITH THE COLD
FRONT...THROUGH THE CWA BY 03Z...AND THE NGM IS THE SLOWEST. WILL
GO WITH MORE OF THE COMPROMISE OF THE AVN WHICH WOULD BRING THE
FRONT THROUGH THE CWA AROUND MIDNIGHT.

MAIN CONCERN WILL BE THE THREAT OF SEVERE WEATHER THIS AFTERNOON AND
EVENING. ALL OF THE FEATURES APPEAR TO BE IN PLACE...GOOD UPPER
DIVERGENCE ASSOCIATED WITH THE RIGHT REAR ENTRANCE REGION OF THE 125
KT JET...50H WINDS INCREASE TO 30 TO 40 KNOTS WHILE 80H WINDS WILL
BE AROUND 30 KTS.  THERE WILL ALSO BE GOOD CONVERGENCE ALONG THE
FRONT AT THE SURFACE TO 80H. RIGHT ALONG THE FRONT THERE WILL BE A
RIBBON OF HIGH THETA-E AIR AT 80H.  MID LEVEL DRY PUNCHES IN BEHIND
THE FRONT AS WELL. THEN COMBINE THAT WITH CAPES EXPECTED TO REACH TO
NEAR 3000 J/KG THIS AFTERNOON WITH TEMPS IN THE LOW TO MID 90S AND
DEW POINTS AS HIGH AS THE MID 70S. THIS COULD SET UP TO BE THE MOST
NUMEROUS SEVERE WEATHER EVENT THIS YEAR...GIVEN THE LIGHT SEVERE
SEASON SO FAR. GIVEN ALL OF THESE FACTORS...WILL WORD POSSIBLE
SEVERE STORMS IN THE ZONES. MAIN THREAT WILL BE WIND DAMAGE...BUT
WITH THE HIGH CAPES COULD GET AN UPDRAFT OR TWO TO PRODUCE MARGINAL
SEVERE HAIL.

CONVECTIVE INITIATION MODEL SUGGEST THUNDERSTORMS DEVELOPING NEAR
THE FRONT AROUND 16Z FROM JUST EAST OF THE BRIDGE TO GAYLORD TO MKG.
THEN STORMS SHOULD MOVE NORTHEAST ALONG THE FRONT...WITH THE SLOW
PROPAGATION SOUTHEAST AS THE FRONT MOVES TOWARD THE CWA. STORMS
SHOULD APPROACH THE TRI CITES AROUND 18Z...BUT MAY NOT REACH DETROIT
UNTIL CLOSER 00Z.

WILL HOLD OFF ON ANY HEAT ADVISORY TODAY. TEMPS AROUND 94 WITH DEW
POINTS AROUND 74 DOES GIVE A HEAT INDEX OF 105...BUT THIS SHOULD BE
THE PEAK CONDITIONS FOR METRO DETROIT. GIVEN THE POTENTIAL OF
CLOUDS...BOTH DEBRIS AND CU FORMING THIS MORNING...MIGHT BE A
STRUGGLE TO REACH MID 90S FOR MORE THAN A HOUR.

BEHIND THE FRONT...THERE WILL BE SOME MOISTURE AT 80H AND BELOW.
EXPECT SKIES TO CLEAR ABOUT 6 HOURS AFTER THE FROPA. THIS WILL LEAD
TO CLEARING SKIES LATE TONIGHT FOR THE TRI CITIES AND THUMB...AROUND
DAYBREAK FOR FNT...AND DURING TUESDAY MORNING FOR METRO DETROIT.
AFTER THAT...DRY AIR TAKES HOLD AND WILL BE IN FOR A SUNNY TUESDAY
AFTERNOON...CLEAR SKIES TUESDAY NIGHT AND MOSTLY SUNNY ON WEDNESDAY.

WILL GO TOWARD THE HIGHER ETA MOS FOR HIGHS TODAY...GIVEN SOME
DECENT SUN AND 80H TEMPS OF +20 TO +21C. THEN ALL THE NUMBERS ARE
CLOSE FOR TONIGHT THROUGH TUESDAY NIGHT...AND DID NOT DIFFER FROM
THEM.

.DTX...NONE.

RBP

MIZ047>049-053>055-060>063-068>070-075-076-082-083-230-

HAZARDOUS WEATHER OUTLOOK FOR SOUTHEAST MICHIGAN
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1106 AM EDT MON JUL 22 2002

...POSSIBLE SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING WITH HOT
AND HUMID CONDITIONS THROUGH THE AFTERNOON...

DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGERS IMMEDIATELY.

HAZARDS...
NUMEROUS THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AND EVENING.
THERE IS A CHANCE OF SEVERE THUNDERSTORMS ACROSS ALL OF SOUTHEAST
LOWER MICHIGAN. SOME OF THESE STORMS WILL HAVE THE POTENTIAL OF
PRODUCING WIND GUSTS UP TO 70 MPH...HAIL UP TO THREE QUARTERS OF AN
INCH IN DIAMETER AND VERY HEAVY RAINFALL.

IN ADDITION...EXCESSIVE HEAT AND HUMIDITY WILL AFFECT SOUTHEAST
LOWER MICHIGAN ESPECIALLY AREAS ALONG AND SOUTH OF INTERSTATE 69.
HIGH TEMPERATURES FROM 88 TO 96 DEGREES...ALONG WITH DEWPOINTS IN
THE MID 70S...WILL RESULT IN HEAT INDICES FROM 100 TO 105 DEGREES.

DISCUSSION...
A STRONG COLD FRONT WILL MOVE ACROSS SOUTHEAST MICHIGAN LATE THIS
AFTERNOON THROUGH THIS EVENING. THUNDERSTORMS ARE STILL EXPECTED TO
DEVELOP AHEAD OF THIS COLD FRONT EARLY THIS AFTERNOON. DUE TO THE
UNSTABLE AIRMASS ALREADY IN PLACE ACROSS SOUTHEAST MICHIGAN...STORMS
WILL HAVE THE POTENTIAL OF DEVELOPING ANYWHERE IN SOUTHEAST MICHIGAN
EARLY THIS AFTERNOON. THE THREAT OF THUNDERSTORMS AND SEVERE WEATHER
WILL END WITH THE PASSAGE OF THE COLD FRONT. THE FRONT SHOULD PASS
THROUGH THE TRI CITIES AROUND 4 PM. FLINT AND THE THUMB SHOULD SEE
THE PASSAGE OF THE FRONT AROUND 6 PM...WHILE THE DETROIT METRO ARE
WILL SEE THE PASSAGE OF THE FRONT AROUND 8 PM. MOVEMENT OF
THUNDERSTORMS IS EXPECTED TO BE NORTHEAST AT 30 MPH.

TEMPERATURES ARE STILL EXPECTED TO CLIMB TO AROUND 90 DEGREES FOR
THE THUMB AND TRI CITIES REGIONS...AND THE LOW TO MID 90S ALONG AND
SOUTH OF INTERSTATE 69. THESE HOT TEMPERATURES...COUPLED WITH DEW
POINTS IN THE MID 70S...WILL PRODUCE HEAT INDICES BETWEEN 100 AND
105 DEGREES.

BE SAFE DURING THE HOT WEATHER. SLOW DOWN AND REDUCE STRENUOUS
ACTIVITIES. WEAR LIGHT WEIGHT AND LIGHT COLORED CLOTHES. DRINK
PLENTY OF WATER AND NON-ALCOHOLIC FLUIDS. STAY OUT OF THE SUN AS
MUCH AS POSSIBLE. TRY TO SPEND SOME TIME IN A COOLER ENVIRONMENT
SUCH AS AN AIR CONDITIONED BUILDING.

SPOTTER ACTIVATION...
SPOTTER ACTIVATION IS LIKELY THIS AFTERNOON INTO EARLY THIS EVENING.

OUTLOOK FOR TUESDAY AND WEDNESDAY...
NO HAZARDOUS WEATHER IS EXPECTED TUESDAY OR WEDNESDAY.

STAY TUNED TO NOAA WEATHER RADIO... OR LOCAL MEDIA OUTLETS... FOR
THE LATEST FORECAST INFORMATION FROM THE NATIONAL WEATHER SERVICE.
YOU CAN ALSO OBTAIN THE LATEST FORECAST ON THE NATIONAL WEATHER
SERVICE WEB SITE.

HTTP://WWW.CRH.NOAA.GOV/DTX/ (ALL LOWER CASE)

CONSIDINE