Severe Thunderstorm Warning 41, NWS Detroit, MI

SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
115 PM EDT WED JUN 26 2002

PLENTY OF MORNING CLOUDS ACROSS SOUTHEAST LOWER WILL DELAY ONSET OF
ORGANIZED CONVECTION FOR A FEW MORE HOURS. AREA JUST NORTH OF THE
SAGINAW BAY RECEIVED PLENTY OF SUNSHINE LATE THIS MORNING AND EARLY
AFTERNOON AND CAPES HAVE JUMPED UP TO AROUND 3000J/KG...AND
CONVECTION BEGINNING TO FIRE AS TEMPERATURES CLIMB THROUGH THE LOWER
80S. LATEST VISIBLE SATELLITE LOOP INDICATES CLEARING TREND OVER
THUMB...SAGINAW AND GENESEE VALLEY AREA AND ANTICIPATE CONVECTION TO
FIRE IN THIS REGION BETWEEN 2 AND 4 PM...AND SLIDE SOUTH THROUGH THE
EVENING HOURS. SURFACE FRONT STILL OVER THE WESTERN U.P. AND
NORTHWEST WISCONSIN...AND MOVING VERY SLOWLY...IN ADDITION DEW
POINTS REMAIN IN THE MID AND UPPER 60S INTO CENTRAL WISCONSIN JUST
AHEAD OF THE FRONT.

MODELS IN GENERAL AGREEMENT THROUGH 60 HOURS...WITH THE ETA A LITTLE
SLOWER WITH THE SOUTHWARD PROGRESSION OF THE COLD FRONT. PREFER THE
SLOWER ETA SOLUTION FOR SEVERAL REASONS. ETA HAS HANDLED THIS FRONT
BETTER THAN THE AVN DURING THE LAST 24 HOURS...AND THE ETA 6-12 HOUR
QPF FIELDS ARE MUCH BETTER THAN THE AVN FIELDS. THE ETA QPF FIELD
SHOWS THE CONVECTION FIRING OVER THE NORTHERN SAGINAW VALLEY EARLY
THIS AFTERNOON AND OVER NORTHERN INDIANA...JUST WHERE IT IS
HAPPENING. THE AVN PICKS UP ON THE NORTHERN INDIANA CONVECTION BUT
HAS NO CLUE IN REGARD TO CONVECTION OVER CENTRAL LOWER. WITH
POTENTIAL FOR GOOD SURFACE HEATING NEXT FEW HOURS...MOST OF CWA
SHOULD SEE CAPES CLIMB INTO THE 3000J/KG RANGE...IN ADDITION DEW
POINT POOLING ACROSS THE SAGINAW VALLEY AND WEAK LOW LEVEL
CONVERGENCE IN PLACE...THUS ANTICIPATE LINE OF CONVECTION IN THIS
REGION AT OR BEFORE ZONE ISSUANCE...THUS WILL CONTINUE WITH LIKELY
POPS THIS EVENING. VERTICAL WIND PROFILES STILL ANEMIC...THUS
GREATEST SEVERE THREAT STILL APPEARS TO BE HAIL.

MODELS ALSO SHOW A SERIES OF UPPER WAVES TO AFFECT SOUTHEAST
LOWER...WITH THE ETA A LITTLE MORE AGGRESSIVE. SECONDARY WAVE ON
THURSDAY AFTERNOON A LITTLE CONCERNING AS FRONT BOGS DOWN OVER THE
SOUTHERN PORTION OF THE CWA. ETA SHOWS A SURFACE WAVE DEVELOPING
ALONG THE FRONT IN RESPONSE TO THIS WAVE...ALONG WITH A NORTHWARD
SURGE OF SOME MODEST 850 MB THETA-E ADVECTION. MODELS STILL
INDICATING CAPES AROUND 1000J/KG ACROSS THE FAR SOUTH THURSDAY
AFTERNOON...THUS A MENTION OF THUNDER THROUGH THE DAY STILL LOOKS
REASONABLE. BIG DIFFERENCE IN MODEL INSTABILITY AS WELL...WITH THE
ETA SHOWING LIS AROUND -1 AND THE AVN AROUND +3 BY 18Z. FRONT TO
CLEAR THE STATE BY THURSDAY EVENING...WITH COOLER/DRIER AIR MOVING
INTO ALL OF SOUTHEAST LOWER.

AVN POPS LOOK TOO LOW ON THURSDAY...THUS WILL LEAN TOWARD ETA/NGM
GUIDANCE VALUES.

.DTX...NONE.

GSS

MIZ047>049-053>055-060>063-068>070-075-076-082-083-270900-

HAZARDOUS WEATHER OUTLOOK FOR SOUTHEAST MICHIGAN
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1100 AM EDT WED JUN 26 2002

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

DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGERS IMMEDIATELY.

HAZARD...
SCATTERED THUNDERSTORMS WILL BECOME MORE NUMEROUS THIS AFTERNOON AND
EVENING. SOME OF THESE STORMS MAY BECOME SEVERE...PRODUCING WIND
GUSTS TO 60 MPH...DIME-SIZE HAIL...AND HEAVY RAINFALL. THE STRONGEST
STORMS WILL OCCUR BETWEEN 4 PM AND 10 PM. STORMS THAT DEVELOP WILL
MOVE EAST AT 15 MPH.

DISCUSSION...
VERY WARM AND HUMID AIR WILL REMAIN IN PLACE OVER SOUTHEAST MICHIGAN
THIS AFTERNOON...AS A LOW PRESSURE SYSTEM TRACKS NORTH OF LAKE
SUPERIOR AND INTO QUEBEC TONIGHT. THE COLD FRONT ASSOCIATED WITH
THIS SYSTEM WILL MOVE FROM WISCONSIN INTO LOWER MICHIGAN THIS
AFTERNOON...AND ACROSS SOUTHEAST MICHIGAN TONIGHT.

AS THE FRONT APPROACHES THIS AFTERNOON AND EVENING...MORE ORGANIZED
THUNDERSTORM ACTIVITY WILL DEVELOP ACROSS THE AREA. THERE IS A
SLIGHT CHANCE THAT SOME OF THESE STORMS MAY BECOME SEVERE...PRODUCING
WIND GUSTS TO 60 MPH AND DIME-SIZE HAIL. IN ADDITION...THE SLOW
MOVEMENT OF THESE STORMS COMBINED WITH ABUNDANT MOISTURE IN PLACE
WILL LEAD TO HEAVY DOWNPOURS. THE MAIN THREAT FOR SEVERE WEATHER WILL
BE BETWEEN 4 PM AND 10 PM.

SPOTTER ACTIVATION...
SPOTTER ACTIVATION MAY BE REQUIRED LATE THIS AFTERNOON AND EVENING.

OUTLOOK FOR THURSDAY AND FRIDAY...
THERE IS A SLIGHT CHANCE OF THUNDERSTORMS ON THURSDAY ALONG AND
SOUTH OF INTERSTATE 94. THESE STORMS ARE NOT EXPECTED TO BE SEVERE.

STAY TUNED TO NOAA WEATHER RADIO...OR LOCAL MEDIA OUTLETS...FOR
THE LATEST FORECAST INFORMATION FROM THE NATIONAL WEATHER SERVICE.
YOU CAN ALSO OBTAIN THE LATEST FORECAST ON THE NATIONAL WEATHER
SERVICE WEB SITE.

HTTP://WWW.CRH.NOAA.GOV/DTX/ (ALL LOWER CASE)

BRAVENDER