Severe Thunderstorm Warning 109, NWS Detroit, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
430 AM EDT WED AUG 2 2000

FOCUS OF ATTENTION TODAY WILL BE FRONT CROSSING CWA FINALLY PUTTING
AN END TO WHAT WILL BE NEARLY ONE WEEK OF DAILY RAIN.

TWO PRECIPITATION PRODUCERS AFFECTING CWA TODAY. FIRST WILL BE UVV
PRODUCED BY DPVA ASSOCIATED WITH VORT MAX NEAR CHICAGO THAT WILL
SWING ACROSS SOUTHERN TIER OF MI COUNTIES THROUGH MORNING INTO EARLY
AFTERNOON. ENHANCING THIS PRECIP FIELD WILL BE AREA OF 850 MB
THETA-E ADVECTION CROSSING CWA THIS MORNING. BEST THETA-E ADVECTION
WILL BE CENTRAL AND NORTHERN PORTIONS OF CWA...WHILE BEST LIFT
ASSOCIATED WITH VORT MAX WILL BE IN SOUTHERN CWA.

SECOND PRECIPITATION PRODUCER WILL BE FRONT CROSSING CWA...AND
ASSOCIATED LOW LEVEL CONVERGENCE. FRONT TAKES TIME CLEARING CWA AS
SERIES OF WAVES MOVING ALONG FRONT SLOW DOWN ITS SOUTHWARD PROGRESS.
FRONT CLEARS NORTHERN PORTION OF CWA DURING THE EARLY TO MID
AFTERNOON...AND SOUTHERN PART OF THE CWA DURING THE EVENING. LOW
LEVEL CONVERGENCE ASSOCIATED WITH FRONT IS RELATIVELY WEAK...AND
WITH UPPER LEVEL SUPPORTING DYNAMICS GONE /FRONT DROPS ACROSS CWA IN
REGION OF GENERALLY DNVA/...DO NOT EXPECT FRONT TO BE POTENT PRECIP
PRODUCER. HOWEVER...WITH FRONT LURKING ABOUT CWA DURING PERIOD OF
MAX HEATING WILL LIKELY SEE SHOWERS AND THUNDERSTORMS THIS
AFTERNOON.

SEVERE POTENTIAL LOOKS TO BE LIMITED...ALTHOUGH NOT NIL. KEY TO
SEVERE WILL BE CLOUD COVER. BUFKIT ETA HOURLY TEMPERATURES SHOW MAX
FOR DTW TO BE ABOUT 73 TODAY...WHILE FWC AND FAN GUIDANCE RUNNING IN
THE LOW TO MID 80S. ETA BRINGS IN MORNING RAIN...THEN CLOUDS HOLDING
DOWN TEMPERATURES. BASED ON SATELLITE TRENDS AND EXPECTED SCENARIO
TODAY...BELIEVE FWC/FAN TEMPERATURES MORE REALISTIC. KEY THRESHOLD
WILL BE 70 DEGREE DEWPOINT. MESOETA SHOWS 70 DEGREE DEW POINTS TO
POOL ALONG FRONT ROUGHLY CENTERED ON 00Z...MAINLY ACROSS FAR
SOUTHEAST PORTION OF CWA. TEMPERATURES IN THE LOW TO MID 80S WITH 70
DEGREE TDS WILL PRODUCE CAPES IN 2500 TO 3000 J/KG RANGE. WIND
FIELDS NOT SUPPORTIVE OF SEVERE...WITH 20 TO 25 KNOT WINDS STEADY
FROM 850 THROUGH 500 MB. HOWEVER...EXTREMELY DRY AIR AT MID AND UPPER
LEVELS WILL FILTER INTO CWA DURING AFTERNOON AND EVENING HOURS. THIS
WILL ADD TO SEVERE THREAT CREATING POTENTIAL FOR WIND DAMAGE AND
HAIL AS WELL. BEST GUESS NOW IS THAT MAIN THREAT FOR AFTERNOON WILL
BE PULSE TYPE SEVERE STORMS...MAINLY ISOLATED.

WILL NEED TO CARRY A CHANCE OF SHOWERS AND THUNDERSTORMS FOR CWA
INTO THE EVENING AS FRONT WILL STILL BE A FACTOR ACROSS SOUTHERN
CWA...AND VORT LOBE WILL SWING ACROSS NORTH. WILL ADD MENTION OF
PATCHY FOG OVERNIGHT...AS SATURATED GROUND AND CLEARING SKIES LIKELY
TO AID FOG DEVELOPMENT. DECIDED ON PATCHY BECAUSE WINDS DO NOT GO
CALM...AND DEW POINTS DROP THROUGH THE NIGHT.

TOMORROW...DRY AIR FILTERS INTO CWA...BRINGING PARTLY SUNNY SKIES.
CU SCHEME KICKS UP QUITE A BIT FOR AFTERNOON...BUT WILL LEAVE PARTLY
SUNNY SKIES GOING FOR NOW. WILL CONTINUE WITH MENTION OF SHRA FOR
SOUTHERN CWA WHERE INSTABILITY IS GREATEST DURING THE AFTERNOON...
AND TAPER TO NIL FOR NORTH...WITH INTERMEDIATE SLIGHT CHANCE FOR
CENTRAL.

WILL FAVOR FWC TEMPERATURES FOR FORECAST.

.DTX...NONE.

OKEEFE

MIZ047>049-053>055-060>063-068>070-075-076-082-083-021200-

SEVERE WEATHER OUTLOOK FOR SOUTHEAST MICHIGAN
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
520 AM EDT WED AUG 2 2000

...SEVERE WEATHER POTENTIAL STATEMENT FOR SOUTHEAST MICHIGAN...

DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGERS IMMEDIATELY.

SCATTERED THUNDERSTORMS WILL OCCUR MAINLY IN THE SAGINAW VALLEY
EARLY THIS MORNING. A FEW OF THESE STORMS WILL APPROACH SEVERE
LIMITS. DUE TO THE MARGINAL NATURE OF THE STORM STRENGTH...SPOTTER
ACTIVATION IS UNLIKELY THIS MORNING.

THUNDERSTORMS WILL CONTINUE TO DEVELOP EARLY THIS MORNING AS
MOISTURE SURGES INTO THE AREA AHEAD OF A COLD FRONT. THIS FRONT WILL
CONTINUE TO MOVE TOWARD THE AREA FROM THE UPPER PENINSULA DURING THE
DAY. THE STORMS EARLY THIS MORNING WILL MOVE EAST AT ABOUT 30 MPH
AND WILL BE CAPABLE OF HAIL AROUND ONE HALF INCH AND WIND GUSTS
AROUND 40 MPH. STORMS OF THIS NATURE WILL TEND TO DIMINISH SHORTLY
AFTER SUNRISE...WITH ADDITIONAL DEVELOPMENT EXPECTED LATER TODAY AS
THE COLD FRONT ENTERS SOUTHEAST MICHIGAN.

KEEP ABREAST OF THE LATEST WEATHER INFORMATION BY LISTENING TO NOAA
WEATHER RADIO...AS WELL AS YOUR LOCAL RADIO...TELEVISION...AND CABLE
TELEVISION STATIONS.

BT