Severe Thunderstorm Warning 85, NWS Detroit, MI

SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1128 AM EDT FRI SEP 20 2002

FORECAST UPDATE REVOLVES AROUND THUNDERSTORM/SEVERE WEATHER CHANCES
FOR THE AFTERNOON.

12Z RAOBS/WATER VAPOR LOOP SHOW SHORTWAVE OVER MINNESOTA/IOWA WITH
HIGH OVER THE SOUTHEAST CONUS. SURFACE ANALYSIS SHOWS COLD FRONT
JUST ABOUT NORTH-SOUTH ALONG THE MISSISSIPPI VALLEY. CONTINUED
STRONG SOUTHERLY FLOW HAS BROUGHT PLENTY OF GULF MOISTURE INTO THE
GREAT LAKES...WITH PRECIPITABLE WATER AT DTX THIS MORNING 1.89...A
DECENT AMOUNT FOR MID SUMMER AND ALMOST 250 PERCENT OF NORMAL FOR
MID SEPTEMBER.

ONE LEAD VORT CENTER MOVING INTO SOUTHERN LOWER MICHIGAN FROM
INDIANA. REGIONAL RADARS SHOW A WIDESPREAD SHIELD OF RAIN WITH THIS
FEATURE...WITH ONLY A FEW THUNDERSTORMS ON THE LEADING EDGE. THIS
AREA OF RAIN AND CLOUDS MAY BE OUR SAVING GRACE AS FAR AS SEVERE
WEATHER GOES. STRONG DYNAMICS ASSOCIATED WITH THE APPROACHING
SYSTEM...850MB WINDS NEAR 40KTS/500MB NEAR 60KTS AND LOCATED NEAR
THE RIGHT-ENTRANCE TO A 100KT 300MB JET. AMOUNT OF INSTABILITY WILL
BE THE BIG QUESTION MARK. FIRST BATCH OF RAIN SHOULD MOVE THROUGH
EARLY THIS AFTERNOON...AND LEAVE A DECENT CLOUDS SHIELD BACK TO THE
FRONT. HOWEVER MODIFIED 12Z DTX SOUNDING FOR SURFACE T/TD OF 80/69
GIVES A CAPE OF 2000J/KG. EARLY PRECIP MAY HELP TO WRING OUT SOME OF
THAT INSTABILITY AHEAD OF TIME AS WELL THOUGH. BUT STILL WITH THE
AMOUNT OF MOISTURE AVAILABLE...NEARLY SATURATED PROFILE WILL BE ABLE
TO CONVECT WITH VERY LITTLE OF THE FORCING/INSTABILITY GOING TOWARD
SATURATING THE COLUMN. HAVE ISSUED THE MORNING OUTLOOK MENTIONING
SEVERE WEATHER POSSIBLE...EMPHASIZING THAT THE THREAT WILL LIKELY
REVOLVE AROUND THE AMOUNT OF HEATING WE RECEIVE. WET-BULB ZERO
HEIGHTS/FREEZING LEVELS ARE ABOVE 13KFT/14KFT. WITH THE STRONG WIND
FIELD...DAMAGING GUSTS WILL BE THE MAIN CONCERN...ESPECIALLY WITH
STORM MOTION ITSELF EXPECTED NEAR 30KTS. SR-HELICITY ALSO CONTINUES
TO INCREASE DURING THE DAY...WITH STORM ROTATION SIMILAR TO
YESTERDAY POSSIBLE. ALSO WITH HIGH PRECIPITABLE WATERS...HEAVY
RAINFALL WILL LIKELY BE AN ISSUE WITH THE STRONGER CONVECTIVE
ELEMENTS.

.DTX...NONE.

BRAVENDER

PRELIMINARY LOCAL STORM REPORT SUMMARY FOR SEPTEMBER 19 2002
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
955 AM EDT FRI SEP 20 2002

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

0438 PM    PERRY                     MI   .88 INCH HAIL
09/19/02   SHIAWASSEE                     REPORTED BY LAW
                                          ENFORCEMENT.

0450 PM    MIDLAND                   MI   WIND DAMAGE
09/19/02   MIDLAND                        TREES DOWN AND UPROOTED.
                                          REPORTED BY SPOTTERS.

0500 PM    MIDLAND                   MI   WIND DAMAGE
09/19/02   MIDLAND                        NUMEROUS LARGE TREES DOWN.
                                          REPORTED BY LAW
                                          ENFORCEMENT.

0500 PM    5 SW BAY CITY             MI   WIND DAMAGE
09/19/02   BAY                            SEVERAL LARGE TREES DOWN.
                                          8-10 GARAGE DOORS BLOWN IN.
                                          REPORTED BY SPOTTERS.

0505 PM    1 NE WILLARD              MI   WIND DAMAGE
09/19/02   BAY                            LARGE LIMBS IN ROAD.
                                          REPORTED BY SPOTTERS.

0615 PM    3 S ADRIAN                MI   WIND DAMAGE
09/19/02   LENAWEE                        LARGE TREE LIMBS BLOWN
                                          DOWN. 150 POUND SWING BLOWN
                                          OVER. REPORTED BY SPOTTERS.

0657 PM    4 NE BRIGHTON             MI   WIND DAMAGE
09/19/02   LIVINGSTON                     LARGE TREE BLOWN OVER.
                                          REPORTED BY SPOTTERS.

0702 PM    2 W MILFORD               MI   WIND DAMAGE
09/19/02   OAKLAND                        SIX INCH DIAMETER TREE
                                          DOWN. REPORTED BY SPOTTERS.

0706 PM    AUGUSTA TOWNSHIP          MI   WIND DAMAGE
09/19/02   WASHTENAW                      EIGHT INCH DIAMETER TREE
                                          LIMBS DOWN. REPORTED BY
                                          SPOTTERS.

0845 PM    ALGONAC                   MI   WIND DAMAGE
09/19/02   ST CLAIR                       SEVERAL LARGE TREES AND
                                          PWER LINES DOWNED. REPORTED
                                          BY SPOTTERS.

MIZ047>049-053>055-060>063-068>070-075-076-082-083-210400-

HAZARDOUS WEATHER OUTLOOK FOR SOUTHEAST MICHIGAN
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1017 AM EDT FRI SEP 20 2002

DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGERS IMMEDIATELY.

HAZARD...
NUMEROUS SHOWERS AND THUNDERSTORMS WILL AFFECT SOUTHEAST MICHIGAN
THIS AFTERNOON AND EVENING. SOME OF THESE STORMS MAY BECOME
SEVERE...WITH WIND GUSTS TO 60 MPH THE PRIMARY HAZARD. HEAVY
DOWNPOURS ARE ALSO LIKELY.

DISCUSSION...
A COLD FRONT AND UPPER WAVE NEAR WISCONSIN WILL MOVE INTO LOWER
MICHIGAN BY THIS EVENING...PROVIDING THE FOCUS FOR THUNDERSTORM
DEVELOPMENT. WITH A WARM AND VERY MOIST AIRMASS IN PLACE ACROSS
SOUTHEAST MICHIGAN...NUMEROUS THUNDERSTORMS ARE EXPECTED THIS
AFTERNOON AND EVENING. THE STRENGTH OF THESE THUNDERSTORMS WILL BE
CLOSELY TIED TO THE AMOUNT OF INSOLATION RECEIVED ACROSS SOUTHEAST
MICHIGAN. CLOUDS AND SCATTERED SHOWERS DURING THE MORNING HAVE HELPED
TO STABILIZE THE ATMOSPHERE. WITH MINIMAL HEATING...COMBINED WITH
STRONG DYNAMICS ASSOCIATED WITH THE APPROACHING SYSTEM...SOME OF THE
THUNDERSTORMS THAT DEVELOP MAY REACH SEVERE LEVELS.

WITH MODERATE DESTABILIZATION THIS AFTERNOON...SOME THUNDERSTORMS
MAY BECOME SEVERE AND PRODUCE WIND GUSTS TO 60 MPH. HEAVY RAINFALL
IS ALSO LIKELY. THUNDERSTORMS THAT DEVELOP WILL MOVE NORTHEAST AT
35 MPH.

SPOTTER ACTIVATION...
SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON.

OUTLOOK FOR SATURDAY AND SUNDAY...
NO HAZARDOUS WEATHER IS EXPECTED.

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)

BRAVENDER