Severe Thunderstorm Warning 19, NWS Detroit, MI

SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
405 PM EDT TUE MAY 15 2001

LONG BUT NARROW BAND OF CONVECTION FIRING NORTH OF SURFACE WARM
ALONG 850 THETA E GRADIENT AND ALSO BEING HELPED BY ELONGATED 500MB
VORT. SFC WARM FRONT SHOULD CONTINUE TO MOVE BACK SOUTHWEST INTO
NORTHERN INDIANA THIS EVENING BEFORE SLOWLY LIFTING BACK NORTHEAST
OVERNIGHT AND WEDNESDAY.  THE CURRENT CONVECTION SHOULD DISSIPATE
SOME DURING THE EVENING WHILE DRIFTING SOUTHWESTWARD ALONG WITH THE
LOWER LEVEL SUPPORT....THEN MOVE SLOWLY BACK NORTHEAST ACROSS THE
FORECAST AREA OVERNIGHT...SOMEWHAT SIMILAR TO LAST NIGHT.  MODELS
SHOW DECENT SHORTWAVE PASSING ACROSS THE AREA 12-18Z WEDNESDAY...
THIS WILL INCREASE SHOWER AND THUNDERSTORM ACTIVITY.  SURFACE BASE
CAPES AND LIS ARE NIL OVERNIGHT AND WEDNESDAY MORNING...
HOWEVER...850 LIS BECOME NEGATIVE BY MORNING ACROSS WESTERN
COUNTIES AND SPREAD EAST DURING THE MORNING.  THIS WILL LEAD TO SOME
ELEVATED CONVECTION. DURING WED...A WEAK SURFACE LOW DEVELOPS OVER
LAKE MICHIGAN ALONG COLD FRONT. THIS LOW WILL HELP LIFT WARM FRONT
TO THE SAGINAW VALLEY VALLEY BY EVENING.  SURFACE CAPES RISE IN THE
1000-2000 RANGE IN THE EVENING WHILE LIS GETTING TO ABOUT  MINUS 5.
THIS IS ENOUGH INSTABILITY TO KEEP CHC POPS FOR THUNDERSTORMS WITH
WEAK FORCING AROUND.

AFTER THAT...WEAK HIGH PRESSURE RIDGING WILL BRING TRANQUIL WEATHER
FOR THURSDAY BEFORE NEXT COLD FRONT SWINGS THROUGH THURSDAY NIGHT
AND EARLY FRIDAY WITH THE NEXT SHOT OF SHOWERS.

PRECIPITAL WATER IN THE 1.25 TO 1.50 RANGE OVERNIGHT AND WEDNESDAY.
COULD LEAD TO SOME LOCALLY HEAVY DOWNPOURS. MOST OF FORECAST AREA
RECEIVED LIGHT AMOUNTS OF RAINFALL OVERNIGHT AS OPPOSED TO THE
SEVERAL INCHES THAT FELL TO THE WEST OF THE FORECAST AREA. SO NO
FLOOD WATCHES SHOULD BE NEEDED.

.DTX...NONE.

DRC

MIZ047>049-053>055-060>063-068>070-075-076-082-083-161200-

SEVERE WEATHER OUTLOOK FOR SOUTHEAST LOWER MICHIGAN
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
455 PM EDT TUE MAY 15 2001

DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGERS IMMEDIATELY.

THERE IS A GOOD CHANCE OF THUNDERSTORMS THIS EVENING...ALONG AND
WEST OF A LINE FROM SAGINAW TO MONROE. THIS INCLUDES THE CITIES OF
SAGINAW...FLINT...ANN ARBOR...MONROE...AND ADRIAN. SOME OF THESE
THUNDERSTORMS ARE EXPECTED TO BECOME SEVERE AND PRODUCE HAIL TO
THREE QUARTERS OF AN INCH IN DIAMETER. THEREFORE SPOTTER ACTIVATION
WILL BE REQUIRED.

THERE IS ANOTHER CHANCE OF THUNDERSTORMS OVERNIGHT ALONG AND WEST
OF U S 23...INCLUDING SAGINAW...FLINT...ANN ARBOR AND ADRIAN. THERE
IS A SLIGHT CHANCE SOME OF THESE STORMS MAY ALSO BECOME SEVERE.

A WARM FRONT WILL REMAIN WEST OF SOUTHEAST MICHIGAN THIS EVENING AND
TONIGHT. THIS WILL KEEP THE REGION IN RELATIVELY COOL STABLE
AIR...LIMITING THE SEVERE THUNDERSTORM GUST POTENTIAL...HOWEVER SOME
OF THESE STORMS COULD PRODUCE LARGE HAIL.

TONIGHT...A THUNDERSTORM COMPLEX IS EXPECTED TO DEVELOP IN WISCONSIN
AND TRACK SOUTHEAST ACROSS MICHIGAN. SOME OF THESE THUNDERSTORMS MAY
SLIDE INTO WESTERN AREAS OF SOUTHEAST MICHIGAN...ALONG AND WEST OF U
S 23. THERE IS A SLIGHT CHANCE SOME OF THESE STORMS MAY BE SEVERE.

THE MAIN THREAT FROM ALL OF THESE STORMS IS HAIL TO THREE QUARTERS
OF AN INCH IN DIAMETER...AND LOCALLY HEAVY RAINFALL. IN AREAS WHERE
THUNDERSTORMS OCCUR...RAINFALL RATES OF ONE INCH PER HOUR ARE
POSSIBLE. THE EXPECTED TIME OF THE MAIN THREAT WILL BE  FROM 5 PM TO
10 PM AND BETWEEN 2 AM AND 8 AM...WITH SOME STORMS LINGERING UNTIL
JUST AFTER 8 AM. LOOK FOR THESE STORMS TO TRACK SOUTHEAST AT 40 MPH.

STAY TUNED TO YOUR FAVORITE MEDIA OUTLET FOR THE LATEST WEATHER
INFORMATION FROM THE NATIONAL WEATHER SERVICE.  YOU CAN ALSO CONTACT
YOUR NATIONAL WEATHER SERVICE ONLINE AT
HTTP://WWW.CRH.NOAA.GOV/DTX/START.HTM (ALL SMALL CASE)

OKEEFE/GSS