Severe Thunderstorm Warning 64, NWS Detroit, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
327 PM EDT THU JUN 29 2000

SCATTERED SHOWER AND THUNDERSTORM ACTIVITY, ASSOCIATED WITH A FAIRLY
VIGOROUS SHORTWAVE FOR JUNE, WILL CONTINUE INTO THE EARLY EVENING.
THE COVERAGE WILL DIMINISH RAPIDLY AS THE WAVE EXITS AND DIURNAL
INSOLATION DECREASES.  STABLE LAYER DOWNSTREAM OF LAKE MICHIGAN IS
MAKING SLOW BUT STEADY PROGRESS EASTWARD AS THE WESTERLY GRADIENT
FLOW INCREASES.  THE CU FIELD BEHIND THE PRIMARY 850-500 DCVA AXIS
REMAINS TAME AT BEST.  EXPECT THAT THE RESIDUAL CU WILL DISSIPATE
RAPIDLY WITH SUNSET, ENOUGH SO TO SEE MOSTLY CLEAR SKIES TONIGHT.

NCEP SUITE IN REASONABLE AGREEMENT WITH THE FEATURES THAT WILL
AFFECT THE LAKES REGION THROUGH THE NEAR TERM.  MODEL TRENDS
INDICATING GREATER AMPLIFICATION OF LONGWAVE RIDGE OVER THE ROCKIES,
MOSTLY DUE TO THE SLOWER PROGRESSION OF THE EASTERN PACIFIC LONGWAVE
TROUGH.  THE RIDGE AMPLIFICATION SHOULD AID IN PREVENTING THE NEXT
SHEAR AXIS SHORTWAVE FROM DIGGING INTO THE CENTRAL LAKES REGION.
MID TROPOSPHERIC TEMPS WILL INCREASE A COUPLE OF DEGREES FOR FRIDAY,
WITH BROAD SUBSIDENCE BECOMING ESTABLISHED OVER THE CWFA.  MID-LEVEL
LAPSE RATES SHOULD REMAIN STEEP ENOUGH TO PRODUCE ALTOCU IN
CONJUNCTION WITH SOME ELEVATED MOISTURE, ESPECIALLY FROM FLINT
ACROSS THROUGH THE THUMB.  OTHERWISE, ETA CU SCHEME SHOWS VERY
LITTLE SUPPORT FOR LOWER BASE CU AS THE BOUNDARY LAYER DRIES OUT.

SURFACE RIDGE WILL SLIDE TO THE SOUTH OF THE STATE FRIDAY SETTING UP
A RETURN TO SOUTHWESTERLY FLOW.  UPSTREAM TEMPS SUPPORT FWC TEMPS FOR
FRIDAY.  STRONG WARM ADVECTION AT 850 AND 700MB WILL BECOME
ESTABLISHED OVER THE WESTERN PORTION OF THE REGION SATURDAY AS THE
LONGWAVE RIDGE CONTINUES TO AMPLIFY OVER THE CENTRAL U.S.  THIS WILL
CONTINUE TO INCREASE DAILY MAXES AS HOLIDAY WEEKEND BEGINS.

AS FOR THE EXTENDED...BROAD MID AND UPPER TROPOSPHERIC RIDGE WILL
EXPAND ACROSS THE PLAINS EASTWARD AS THE WEEKEND PROGRESSES.
EXTENDED PROGS ARE IN REASONABLE AGREEMENT WITH THE OVERALL
DEVELOPMENT OF THE RIDGE.  HOWEVER, EVOLUTION OF THE DEEPENING
HUDSON BAY LOW DIFFERS AMONG THE PROGS.  THE CMC GLOBAL SOLUTION IS
POSITIONED THE FARTHEST SOUTH WITH THE MRF BEING THE MOST AGGRESSIVE
WITH DEEPENING OF THE HUDSON LOW.  THE LOCALLY RUN ETA-XX MAINTAINS
THE RIDGE OVER THE REGION WHICH APPEARS MORE REASONABLE COMPARED TO
THE MRF SOLUTION, WHICH IS ALSO SUPPORTED BY THE 12Z AVN AND
ETA-XX.  THE WESTERLIES WILL CONTAIN SOME TRANSIENT SHORTWAVE
FEATURES, POSSIBLY A RESULT OF MCS DEVELOPMENT, ALONG THE NORTHERN
PERIPHERY.  THE ETA-XX KEEPS THE 850-300MB THICKNESS GRADIENT TO THE
NORTH OF THE CWFA FOR TUESDAY, BUT THE MRF AND CMC SOLUTIONS ARE
FARTHER SOUTH.  GIVEN THE UNCERTAINTY OF THE PHASE AND AMPLITUDE AND
ANY SHORTWAVE IN THE WESTERLIES, WILL KEEP THE CHANCE OF PRECIP
CONFINED TO MONDAY THIS GO AROUND.

.DTX...!NONE.

MANN

MIZ047>049-053>055-060>063-068>070-075-076-082-083-300000-

SEVERE WEATHER OUTLOOK FOR SOUTHEAST LOWER MICHIGAN
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
314 PM EDT THU JUN 29 2000

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

DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGERS IMMEDIATELY.

SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE THIS AFTERNOON. A
FEW OF THESE THUNDERSTORMS WILL BE SEVERE. SPOTTER ACTIVATION HAS
OCCURRED.

HEATING FROM THE STRONG JUNE SUN WAS COMBINING WITH AN UPPER LEVEL
DISTURBANCE PIVOTING EAST ACROSS SOUTHEAST MICHIGAN...TO PRODUCE
SCATTERED HIT AND MISS THUNDERSTORMS OVER MOST OF SOUTHEAST MICHIGAN
AT 3 PM. MOST THUNDERSTORMS THIS AFTERNOON WILL BE CAPABLE OF
PRODUCING PEA SIZED HAIL...AND A FEW OF THE STORMS WILL PRODUCE
LARGER HAIL...AS LARGE AS ONE INCH IN DIAMETER. IN ADDITION...WIND
GUSTS TO 30 MPH ARE POSSIBLE WITH THE THUNDERSTORMS...ALONG WITH
CLOUD TO GROUND LIGHTNING AND BRIEF DOWNPOURS OF RAIN.

THUNDERSTORMS WILL DECREASE IN COVERAGE BY 5 PM...AND WILL HAVE
ENDED ALTOGETHER BEFORE 8 PM. THUNDERSTORM MOVEMENT WILL BE TOWARD
THE SOUTHEAST AROUND 20 MPH.

STAY TUNED TO NOAGA WEATHER RADIO...OR YOUR FAVORITE MEDIA
OUTLET...FOR THE LATEST WEATHER INFORMATION.

DWD