Hail in Michigan, May 11, 2001

SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
326 PM EDT FRI MAY 11 2001

SCATTERED SHOWERS AND THUNDERSTORMS DOT THE SOUTHEAST MICHIGAN
LANDSCAPE THIS AFTERNOON.  MUCH OF THE ACTIVITY IS ALONG AND AHEAD
OF A COLD FRONT EXTENDING ACROSS THE STATE FROM SOUTHERN LAKE HURON
TO NEAR SOUTH BEND.  SURFACE TEMPS ACROSS THE FAR SOUTH HAVE JUMPED
TO NEAR 80, UNDER THE INFLUENCE OF MORE SUN EARLIER IN THE DAY,
ALLOWING CAPES TO INCREASE TO NEAR 2KJ/KG.  EXPECT THAT THE
SCATTERED ACTIVITY WILL CONTINUE IN ADVANCE OF THE FRONT THIS
EVENING, ESPECIALLY BEFORE SUNSET.  ADDITIONALLY, A FEW SHOWERS HAVE
DEVELOPED OVER WISCONSIN WITHIN THE MID-TROP TROUGH AXIS. THIS AREA
OF MOISTURE AND LIFT SHOULD AFFECT THE AREA AFTER MIDNIGHT, KEEPING
THE CLOUDS AND CHANCES FOR SHOWERS IN OVERNIGHT.  TEMPS WILL QUICKLY
FALL INTO THE 40S BEHIND THE FRONT WITH ROBUST LOW-LEVEL COLD
ADVECTION FIRMLY IN PLACE ACROSS THE NORTHERN LAKES.

NORTHWESTERLY FLOW ALOFT WILL DOMINATE THE REGION THROUGH THE REST
OF THE NEAR-TERM.  AN EMBEDDED SHORTWAVE, PRESENTLY OVER WESTERN
CANADA WILL SLIP OVER THE LONGWAVE RIDGE OVER THE NORTHERN PLAINS
THEN DIVE THROUGH THE NORTHEASTERN LAKES REGION BY SUNDAY.  NCEP/DTX
MODELS DIFFER SLIGHTLY ON THE TIMING.  THE AVN IS THE LEAST
AMBITIOUS WITH THE MOISTURE PARAMETERS.  HOWEVER, THE DTX ETA-XX
(DESPITE BEING INITIALIZED WITH AVN DATA) IS QUITE SIMILAR TO THE
OPERATIONAL ETA.  ADDITIONALLY, 36H DRPOG/DT SUPPORTS THE ETA
SOLUTION FOR THE REGION.  MODEST 850MB THETA-E RIDGING AND WEAK
QG-FGEN ALONG WITH COLD ADVECTION IN THE 700-500MB LAYER WILL ALSO
STEEPEN LAPSE RATES TO AROUND 6.5C/KM, SUPPORTING THE POTENTIAL FOR
SHOWERS ACROSS THE NORTHERN PORTIONS OF THE CWFA SUNDAY AFTERNOON
AND INTO THE EVENING ELSEWHERE.

IN THE MEANTIME, SIGNIFICANT COOLING IN THE SUB-850MB LAYER WILL
ALLOW DIURNAL CU TO DEVELOP AND PERSIST THROUGH THE DAY SATURDAY,
KEEPING SKIES PARTLY SUNNY (IF NOT MOSTLY CLOUDY AT TIMES).
LOW-LEVEL MOISTURE WILL DECREASE AS A RESULT OF THE DIURNAL CLOUD
DEVELOPMENT, ALLOWING SKIES TO CLEAR SATURDAY NIGHT.  CLOUDS THEN
WILL INCREASE ONCE AGAIN IN ADVANCE OF THE AFOREMENTIONED SHORTWAVE
TROUGH.  WITH PERSIST CLOUDS SATURDAY, TEMPS SHOULD STAY BELOW FWC
VALUES, BUT NOT AS COOL AS ADVERTISED BY THE MAVS.  OTHERWISE, TEMPS
AT OR SLIGHTLY BELOW FWC APPEAR MOST REASONABLE.

EXTENDED PROGS CONTINUE TO SHOW AN AMPLIFYING MID/UPPER TROUGH OVER
THE NORTHEAST CONUS TOWARD MIDWEEK.  THE MRF CONTINUES TO BE THE
MOST AGGRESSIVE WITH LOWERING THE HEIGHTS WESTWARD ACROSS THE LAKES
REGION, NOT AS MUCH AS PREVIOUS RUNS.  BASED ON AVN/MRF TRENDS,
INCLUDING THE 12Z AVN, A SOLUTION CLOSER TO THE ETA-XX AND CMC
GLOBAL.  TIMING OF SHORTWAVES EMBEDDED WITHIN THE NORTHWESTERLY FLOW
WILL BE SOMEWHAT NEBULOUS.  PRECIP CHANCE APPEAR GREATEST ON TUESDAY
AND WEDNESDAY.  KEPT TEMPS AT OR SLIGHTLY ABOVE FMR/MEX VALUES
THROUGH THE PERIOD.

.DTX...NONE.

MANN

MIZ047>049-053>055-060>063-068>070-075-076-082-083-120300-

SEVERE WEATHER OUTLOOK FOR SOUTHEAST LOWER MICHIGAN
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1116 AM EDT FRI MAY 11 2001

DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGERS IMMEDIATELY.

SCATTERED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EARLY EVENING
ALONG AND SOUTH OF I 69. ALONG AND SOUTH OF I 94...THERE IS A SLIGHT
RISK SOME OF THESE THUNDERSTORMS MAY BECOME SEVERE. SPOTTER
ACTIVATION MAY BE REQUIRED LATER THIS AFTERNOON INTO EARLY EVENING.

A COLD FRONT SLOWLY ADVANCING ACROSS SOUTHEAST MICHIGAN TODAY WILL
SLOW ITS PROGRESS AS IT APPROACHES METRO DETROIT THIS AFTERNOON.
THERE IS A CHANCE THUNDERSTORMS WILL DEVELOP ALONG THE FRONT THIS
AFTERNOON AND CONTINUE INTO THE EARLY EVENING.

SHOULD THUNDERSTORMS DEVELOP...THERE IS A SLIGHT CHANCE SOME OF
THESE STORMS COULD BECOME SEVERE ALONG AND SOUTH OF I 94.
CONSIDERABLE CLOUD COVER ACROSS THE REGION TODAY WILL LIMIT
SUNSHINE AND PERMIT THE ATMOSPHERE TO BECOME ONLY MARGINALLY UNSTABLE
IN THE GENERALLY THUNDERSTORM THREAT AREA. HOWEVER...FROM I 94
SOUTH...INCLUDING DETROIT...ANN ARBOR...ADRIAN...AND MONROE...
CONSIDERABLE SUNSHINE THIS MORNING INTO THE EARLY AFTERNOON WILL
PRODUCE MORE FAVORABLE CONDITIONS FOR THE DEVELOPMENT OF SEVERE
THUNDERSTORMS.

THE MAIN THREAT FROM SEVERE THUNDERSTORMS WILL BE HAIL TO ONE INCH
IN DIAMETER AND WIND GUSTS TO 60 MPH. THE MOST LIKELY TIME FOR
SEVERE THUNDERSTORM DEVELOPMENT WILL BE BETWEEN 3 PM AND 8 PM. THESE
STORMS WOULD MOVE WEST AT 15 MPH.

STAY TUNED TO YOUR FAVORITE MEDIA OUTLET FOR THE LATEST WEATHER
INFORMATION FROM THE NATIONAL WEATHER SERVICE.

OKEEFE

MIZ047>049-053>055-060>063-068>070-075-076-082-083-120300-

SEVERE WEATHER OUTLOOK FOR SOUTHEAST LOWER MICHIGAN...CORRECTED
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
225 PM EDT FRI MAY 11 2001

DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGERS IMMEDIATELY.

SCATTERED THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON AND EARLY EVENING
ALONG AND SOUTH OF I 69. ALONG AND SOUTH OF I 94...THERE IS A SLIGHT
RISK SOME OF THESE THUNDERSTORMS MAY BECOME SEVERE. SPOTTER
ACTIVATION MAY BE REQUIRED LATER THIS AFTERNOON INTO EARLY EVENING.

A COLD FRONT SLOWLY ADVANCING ACROSS SOUTHEAST MICHIGAN TODAY WILL
SLOW ITS PROGRESS AS IT APPROACHES METRO DETROIT THIS AFTERNOON.
THERE IS A CHANCE THUNDERSTORMS WILL DEVELOP ALONG THE FRONT THIS
AFTERNOON AND CONTINUE INTO THE EARLY EVENING.

SHOULD THUNDERSTORMS DEVELOP...THERE IS A SLIGHT CHANCE SOME OF
THESE STORMS COULD BECOME SEVERE ALONG AND SOUTH OF I 94.
CONSIDERABLE CLOUD COVER ACROSS THE REGION TODAY WILL LIMIT
SUNSHINE AND PERMIT THE ATMOSPHERE TO BECOME ONLY MARGINALLY UNSTABLE
IN THE GENERALLY THUNDERSTORM THREAT AREA. HOWEVER...FROM I 94
SOUTH...INCLUDING DETROIT...ANN ARBOR...ADRIAN...AND MONROE...
CONSIDERABLE SUNSHINE THIS MORNING INTO THE EARLY AFTERNOON WILL
PRODUCE MORE FAVORABLE CONDITIONS FOR THE DEVELOPMENT OF SEVERE
THUNDERSTORMS.

THE MAIN THREAT FROM SEVERE THUNDERSTORMS WILL BE HAIL TO ONE INCH
IN DIAMETER AND WIND GUSTS TO 60 MPH. THE MOST LIKELY TIME FOR
SEVERE THUNDERSTORM DEVELOPMENT WILL BE BETWEEN 3 PM AND 8 PM. THESE
STORMS WOULD MOVE EAST AT 15 MPH.

STAY TUNED TO YOUR FAVORITE MEDIA OUTLET FOR THE LATEST WEATHER
INFORMATION FROM THE NATIONAL WEATHER SERVICE.

OKEEFE

CORRECTED STORM MOVEMENT DIRECTION.