Severe Thunderstorm Warning 134, NWS Detroit, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
400 AM EDT WED AUG 9 2000

...THREAT OF SEVERE THUNDERSTORMS FOR THIS MORNING INTO EARLY
AFTERNOON...

THIS MORNING THE ETA MODEL INITIALIZED MUCH BETTER (AT LEAST
COMPARED TO YESTERDAYS) WITH AVN NOT THAT FAR BEHIND (IT FINALLY HAS
RESOLVED MID LEVEL FEATURES WITH RESPECT TO STRONG INTENSITY OF
WAVES OF LATE).

MAIN SURFACE BOUNDARY WAS JUST NORTH OF I-69 WITH WINDS VARIABLE TO
NORTH JUST NORTH OF THE FRONT.  SOUTH OF THIS FRONT DEWPOINTS WERE
AROUND 70 WITH A LIGHT SOUTHWEST WIND.  AIR MASS IS STABLE EARLY
THIS MORNING WITH CINH OVER 200 AND LI/S SLIGHTLY ON THE POSITIVE
SIDE.  EVEN TAKING 00Z SOUNDINGS AND LIFTING PARCELS FROM 800 MB DID
NOT YIELD MUCH IN THE WAY OF INSTABILITY.  IN ADDITION RFQ OF 300MB
JET OVER THE REGION SHOULD KEEP THINGS QUIET FOR NOW.  ALL THIS
WOULD EXPLAIN THE WEAKENING OF CELLS AS THEN MOVE INTO CENTRAL
MICHIGAN.

WHAT HAPPENS TOWARD 12Z AND LATER IS A DIFFERENT STORY.  THE
ETA...AND SOMEWHAT THE AVN...PICKED UP A MID LEVEL SHORT WAVE NOW
MOVING INTO IOWA.  THIS HAS ERUPTED THUNDERSTORMS EARLY THIS MORNING
AS PROFILERS 850 LLJ HAS INCREASED THE FUEL OVER THE CENTRAL PLAINS.
THIS WAVE IS FORECAST TO MOVE SOUTH OF THE CWA...ACROSS INDIANA AND
OHIO...THIS AFTERNOON.  WHETHER THIS MAY INHIBIT THUNDERSTORM
CHANCES THIS AFTERNOON IS STILL IN QUESTION AS THIS MIGHT ROB LOW
LEVEL MOISTURE AND RESULTING SINKING AIR TO TAKE AWAY OUR CHANCES
FOR STORM.  BUT ATMOSPHERE IS ALREADY QUITE MOIST SO DO NOT THINK
THIS WILL CAUSE A PROBLEM IN THE FORECAST FOR LATER TODAY.  SPC
SLIGHT RISK OVER THE WHOLE AREA TODAY WITH MODERATE RISK JUST TO OUR
SOUTHEAST.

500/700 MB SHORT WAVES OVER LAKE SUPERIOR THIS MORNING WILL MOVE
SOUTHEAST AS SURFACE WAVE DEVELOPS ACROSS THE STATE.  THINGS DO GET
QUITE UNSTABLE LATE THIS MORNING INTO THE EARLY AFTERNOON WITH LAPSES
RATES GREAT THAN 7/C ... CAPES OVER 4000 J/KG SOUTHEAST...3000 J/KG
NORTHERN CWA... LIS AROUND -6 BY 18Z WITH SWI -3.  WE ARE INITIALLY
CAPPED THIS AM WITH CINH -80 TO -120 THEN NOTHING TO SPEAK OF BY
MIDDAY.  SURF AND 850 THETA E RIDGE AXIS NOSES NORTHEAST ACROSS THE
CWA WITH SPEED SHEAR INCREASING DURING THE MORNING HOURS.  AS LOW
DEVELOPS THIS WILL INTENSIFY THE COLD FRONT AS IT SWING SOUTHEAST
ACROSS THE REGION BY MID AFTERNOON.  PERHAPS A SQUALL LINE
(INITIALLY A FEW SUPERCELLS MAY BE POSSIBLE) DEVELOPING BUT LOTS
WILL TELL ON THE TIMING OF FROPA.

TONIGHT DRY AIR ALONG WITH COLD AIR ADVECTION SHOULD MAKE FOR A
COMFORTABLE NIGHT.  NEXT FEATURE IS ON THURSDAY WITH THE AVN THE
STRONGEST BRINGING A STRONG 500 MB SHORT WAVE ACROSS THE EASTERN
COUNTIES.  WHILE THIS MAY OCCUR THINK THE ETA IS BETTER WITH A
STRING OF VORTICITY.  WITH CAPPING INVERSION AOA 700MB AND LOW LEVEL
CAPES NEAR 100 SHOULD SEE LOTS OF CU WITH EVEN A FEW
SPRINKLES/SHOWERS.

GUIDANCE TEMPS LOOK GOOD BUT THINK AVN MOS IS SLIGHTLY BETTER FOR
THURSDAYS HIGHS.  WILL MONITOR CONVECTION BREAKING OUT TO OUR
NORTHWEST BEFORE ISSUING ZONES AROUND 430 AM.

COORD WITH CLE...APX AND SPC...THANKS!

.DTX...NONE.

BGM

MIZ047>049-053>055-060>063-068>070-075-076-082-083-091500-

SEVERE WEATHER OUTLOOK FOR SOUTHEAST LOWER MICHIGAN
805 AM EDT WED AUG 9 2000

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

DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGERS IMMEDIATELY.

SEVERE THUNDERSTORMS WILL CONTINUE ACROSS THE THUMB REGION THROUGH
10 AM. SPOTTER ACTIVATION HAS TAKE PLACE. THE MAIN THREAT WITH THESE
STORMS WILL BE HAIL TO ONE AND A HALF INCHES IN DIAMETER. THESE
THUNDERSTORMS ARE MOVING SOUTHEAST AT 50 MPH. THE WARM MOIST
UNSTABLE AIR MASS IN PLACE ACROSS THE REGION IS PROVIDING THE
MOISTURE AND INSTABILITY. AN UPPER LEVEL DISTURBANCE CROSSING THE
NORTHERN PART OF SOUTHEAST LOWER MICHIGAN IS PROVIDING THE LIFT.
THIS ACTIVITY WILL DIMINISH BY LATE MORNING AS THE UPPER LEVEL
DISTURBANCE EXITS THE REGION.

SEVERE THUNDERSTORMS WILL ONCE AGAIN BE POSSIBLE ACROSS ALL OF
SOUTHEAST LOWER MICHIGAN LATE THIS MORNING THROUGH THE AFTERNOON.
SPOTTER ACTIVATION WILL LIKELY BE REQUIRED WITH THIS ROUND OF
THUNDERSTORMS AS WELL.

A WARM AND HUMID AIR MASS REMAINS IN PLACE ACROSS ALL OF SOUTHEAST
MICHIGAN. A COLD FRONT CROSSING SOUTHEAST LOWER MICHIGAN LATE THIS
MORNING AND AFTERNOON WILL PROVIDE A FOCUSING MECHANISM FOR MORE
SEVERE WEATHER ACROSS THE REGION. INITIALLY...THUNDERSTORMS WILL BE
SINGULAR IN NATURE BUT AS A COLD FRONT MOVES DOWN FROM THE NORTHWEST
LATE THIS MORNING...A LINE OF STRONG TO SEVERE THUNDERSTORMS IS
EXPECTED TO DEVELOP. THUNDERSTORMS THAT DEVELOP WILL MOVE SOUTHEAST
BETWEEN 25 AND 35 MPH. THE MAIN THREAT WITH THESE STORMS WILL BE
WIND TO 70 MPH. HAIL TO ONE INCH IN DIAMETER IS ALSO POSSIBLE.

THE BEST POTENTIAL FOR SEVERE THUNDERSTORMS LATE THIS MORNING AND
AFTERNOON WILL BE ALONG AND SOUTH OF INTERSTATE 69.  HOWEVER AN
ISOLATED SEVERE THUNDERSTORM WILL BE POSSIBLE ANYWHERE THROUGH EARLY
AFTERNOON. THE COLD FRONT IS EXPECTED TO CLEAR THE SAGINAW AND FLINT
AREAS BY 3 PM DIMINISHING THE SEVERE WEATHER THREAT THERE. SOUTH AND
EAST OF THOSE LOCATIONS ACROSS THE DETROIT METRO VICINITY SEVERE
WEATHER WILL REMAIN A THREAT UNTIL 6 PM.

STAY TUNED TO YOUR FAVORITE MEDIA OUTLET FOR THE LATEST SEVERE
WEATHER INFORMATION.

BGM OKEEFE

MIZ047>049-053>055-060>063-068>070-075-076-082-083-091500-

SEVERE WEATHER OUTLOOK FOR SOUTHEAST LOWER MICHIGAN...CORRECTION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
838 AM EDT WED AUG 9 2000

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

DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGERS IMMEDIATELY.

SEVERE THUNDERSTORMS WILL CONTINUE ACROSS THE THUMB REGION THROUGH
10 AM. SPOTTER ACTIVATION HAS TAKE PLACE. THE MAIN THREAT WITH THESE
STORMS WILL BE HAIL TO ONE AND A HALF INCHES IN DIAMETER. THESE
THUNDERSTORMS ARE MOVING SOUTHEAST AT 50 MPH. THE WARM MOIST
UNSTABLE AIR MASS IN PLACE ACROSS THE REGION IS PROVIDING THE
MOISTURE AND INSTABILITY. AN UPPER LEVEL DISTURBANCE CROSSING THE
NORTHERN PART OF SOUTHEAST LOWER MICHIGAN IS PROVIDING THE LIFT.
THIS ACTIVITY WILL DIMINISH BY LATE MORNING AS THE UPPER LEVEL
DISTURBANCE EXITS THE REGION.

SEVERE THUNDERSTORMS WILL ONCE AGAIN BE POSSIBLE ACROSS ALL OF
SOUTHEAST LOWER MICHIGAN LATE THIS MORNING THROUGH THE AFTERNOON.
SPOTTER ACTIVATION WILL LIKELY BE REQUIRED WITH THIS ROUND OF
THUNDERSTORMS AS WELL.

A WARM AND HUMID AIR MASS REMAINS IN PLACE ACROSS ALL OF SOUTHEAST
MICHIGAN. A COLD FRONT CROSSING SOUTHEAST LOWER MICHIGAN LATE THIS
MORNING AND AFTERNOON WILL PROVIDE A FOCUSING MECHANISM FOR MORE
SEVERE WEATHER ACROSS THE REGION. INITIALLY...THUNDERSTORMS WILL BE
SINGULAR IN NATURE BUT AS A COLD FRONT MOVES DOWN FROM THE NORTHWEST
LATE THIS MORNING...A LINE OF STRONG TO SEVERE THUNDERSTORMS IS
EXPECTED TO DEVELOP. THUNDERSTORMS THAT DEVELOP WILL MOVE SOUTHEAST
BETWEEN 25 AND 35 MPH. THE MAIN THREAT WITH THESE STORMS WILL BE
WIND TO 70 MPH. HAIL TO ONE INCH IN DIAMETER IS ALSO POSSIBLE.

THE BEST POTENTIAL FOR SEVERE THUNDERSTORMS LATE THIS MORNING AND
AFTERNOON WILL BE ALONG AND SOUTH OF INTERSTATE 69.  HOWEVER AN
ISOLATED SEVERE THUNDERSTORM WILL BE POSSIBLE ANYWHERE THROUGH EARLY
AFTERNOON. THE COLD FRONT IS EXPECTED TO CLEAR THE SAGINAW AND FLINT
AREAS BY 3 PM DIMINISHING THE SEVERE WEATHER THREAT THERE. SOUTH AND
EAST OF THOSE LOCATIONS ACROSS THE DETROIT METRO VICINITY SEVERE
WEATHER WILL REMAIN A TH0REAT UNTIL 6 PM.

STAY TUNED TO YOUR FAVORITE MEDIA OUTLET FOR THE LATEST SEVERE
WEATHER INFORMATION.

BGM OKEEFE

MIZ047>049-053>055-060>063-068>070-075-076-082-083-100600-

SEVERE WEATHER OUTLOOK FOR SOUTHEAST LOWER MICHIGAN
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1120 AM EDT WED AUG 9 2000

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

DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGERS IMMEDIATELY.

THERE IS A RISK FOR SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING
ALONG AND SOUTH OF INTERSTATE 69. SPOTTER ACTIVATION MAY BE
NEEDED.

IF THUNDERSTORMS BECOME SEVERE... THE MAIN THREAT WILL BE STRAIGHT
LINE WINDS TO 70 MPH AND UP TO GOLF BALL SIZE HAIL. BRIEF MINOR
FLOODING OF LOW LYING AREAS...SMALL STREAMS AND ROADWAYS ARE ALSO
POSSIBLE WITH ANY THUNDERSTORMS THIS AFTERNOON AND EVENING.
MOVEMENT OF STORMS WILL GENERALLY BE TO THE SOUTHEAST AT 40 MPH.

A COLD FRONT ACROSS NORTHERN LOWER MICHIGAN WILL MOVE SOUTHEAST
THROUGH THE SAGINAW VALLEY AND THUMB REGION EARLY THIS AFTERNOON AND
THEN CONTINUE THROUGH THE DETROIT AREA LATE THIS AFTERNOON...AND
THEN EXITING OUT OF THE STATE BY LATE THIS EVENING.  THE ATMOSPHERE ACROSS
SOUTHEAST LOWER MICHIGAN IS VERY UNSTABLE...ESPECIALLY SOUTH OF
INTERSTATE 69.  THUNDERSTORMS EARLIER THIS MORNING THAT OCCURRED
NORTH OF INTERSTATE 69 HAVE HELPED STABILIZE THE ATMOSPHERE SOMEWHAT.
THIS SHOULD KEEP THUNDERSTORMS FROM BECOMING SEVERE IN THIS AREA.

THE THREAT FOR SEVERE STORMS SHOULD END AFTER 4 PM FROM HOWELL TO
FLINT...AFTER 5 PM FROM LAPEER TO ANN ARBOR AND ADRIAN...AND AFTER 7
PM FROM PORT HURON TO DETROIT AND MONROE.

PERSONS SHOULD KEEP AN EYE TO THE SKY THIS AFTERNOON AND EVENING AND
BE PREPARED TO SEEK SHELTER IF THREATENING WEATHER APPROACHES OR A
SEVERE THUNDERSTORM WARNING IS ISSUED.

STAY TUNED TO YOUR FAVORITE MEDIA OUTLET FOR THE LATEST SEVERE
WEATHER INFORMATION.

DRC