Severe Thunderstorm Warning 63, NWS Detroit, MI

SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1105 AM EDT SUN JUL 6 2003

CURRENT LINE OF STORMS ON WAA SPOKE OF MESO SYSTEM CONTINUES TO PULL
ENE INTO AREA...AND AGREE W/ GRR THAT IT WILL KEEP COMING. WL ADJUST
AFTN ZONES TO INCLUDE CHC POPS THRUOUT CWA. LINE ITSELF WILL HOLD OFF
ENTERING WRN CWA TIL 3-4 PM. HWVR...WOULD EXPECT A FEW CELLS TO DVLP
IN ADVANCE OF IT ON SYNOPTIC FRONT DRAPED THRU MIDDLE OF CWA AS LLVL
FORCING IMPROVES WITH ITS APPROACH. ATMOS WILL REMAIN FAIRLY TAME
STABILITY-WISE INTO THE AFTN SO DON/T EXPECT MUCH MORE THAN SOME
ISOLATED SVR AT BEST.

BETTER POTENTIAL FOR SEVERE WX WL COME THIS EVE/TNGT AS STRONGER LINE
OF STORMS THAT WL INTENSIFY OVER IL IN WARM SECTOR IN ADVANCE OF MVC
THIS AFTN...PROGRESSES INTO THE AREA. THIS VORT CENTER HAS ENHANCED
ENVIRONMENTAL WINDS LOCALLY WITH A 35-40KT H5/30KT H7 WIND NOTED ON
12Z UAA FROM KOAX/KDVN. AIRMASS IN IL ALREADY BECOMING VERY UNSTABLE
W/ LOW/MID 70 DWPTS ADVECTING BACK INTO REGION AND TEMPS CLIMBING
THRU THE 80S.

FOR CWA...MAIN QUESTION WILL BE SOUTHERN EXTENT OF INITIAL LINE OF
STORMS. IF THEY FOCUS MAINLY NORTH...WHICH IS PRETTY REASONABLE SINCE
INSTABILITY WILL BE MINIMIZED IN SRN 1/2 BY FAIRLY THICK CIRRUS AND
INFLUENCE OF COOL POOL OVER OH VALLEY...THEN WARM SECTOR WILL BE ABLE
TO SPREAD FURTHER NE LATE AFTN/EVENING AS MVC APPROACHES & WRN AREAS
COOL POOL OVER INDIANA MIX OUT. THINK THIS IS MOST LIKELY SCENARIO.
WOULD EXPECT THE UNSTABLE AIR OVER THE MIDWEST TO ADVECT NICELY INTO
LOWER MI LATER. WITH THIS IN MIND...WILL BE UPPING POPS TO LIKELY THIS
EVE INTO TNGT...SRN 1/2 IF NOT ALL OF CWA. WL LEAVE SVR MENTION OUT
FOR NOW GIVEN SVRL THINGS HAVE TO HAPPEN TODAY FOR FULL POTENTIAL TO
BE REALIZED TNGT.

UPDATED ZONES BY 1130 AM.

** 346 AM DISCUSSION **

MODELS AGAIN OFFER VARIETY IN THE DETAILS. 500 MB PATTERN
ESSENTIALLY CONTINUES ZONAL FLOW WITH RIPPLES OF ENERGY MOVING
THROUGH IT...THE STRONGEST OF WHICH IS SYNOPTIC SCALE SHORT WAVE
TROUGH SKIRTING CANADIAN BORDER/FAR NORTHERN LAKES REGION MONDAY
LEAVING A LITTLE MORE PLAINS RIDGING IN ITS WAKE. CONVECTIVE COMPLEX
COMING OUT OF IA THIS MORNING IS HANDLED VARIOUSLY BY MODELS.
OVERALL PREFER HANDLING OF ETA/MODIFIED A LITTLE BY NGM WHICH IS
FARTHER NORTH...BUT NOTHING LIKE THE GFS WHICH MAINTAINS A MUCH
STRONGER SYSTEM MOVING ACROSS LOWER MI TONIGHT AS OPPOSED TO MODEL
CONSENSUS OF MUCH FARTHER SOUTH AND WEAKER. GFS APPEARS TO BE
SUFFERING FROM A FEEDBACK PROBLEM. AT THE SURFACE...AGAIN FAVORING
ETA/NGM...SHOWING WEAK RIDGE OVERHEAD RECEDING EAST EAST TODAY AND
TONIGHT FOLLOWED BY COLD FRONT AND SUBSEQUENT TROUGHS IN VICINITY
UNTIL HIGH PRESSURE FINALLY BUILDS IN BY MIDWEEK.

GIVEN MODEL DIFFERENCES...VERTICAL MOISTURE PROFILES ALSO QUITE
DIVERSE...WITH GFS PROBABLY TOO MUCH FOR TODAY AND TOO LITTLE LATE
TONIGHT AND MONDAY...SO WILL DEFER MORE TOWARD ETA...WHICH INCREASES
PRECIPITABLE WATER TO AROUND 1.5 INCHES TONIGHT AND MONDAY.

WILL MENTION AREAS OF FOG UNTIL MID MORNING...AIDED BY CLEAR SKIES
OVERNIGHT AS PER CURRENT OBSERVATIONS...BUT NOT WIDESPREAD ENOUGH
FOR ADVISORY. WILL CALL PARTLY SUNNY TODAY...WITH MORNING CLOUDS
CONFINED MAINLY TO CIRRUS BLOWOFF FROM UPSTREAM.

GIVEN EXPECTED TRACK OF CONVECTIVE COMPLEX FROM IA...WILL CALL FOR
CHANCE POPS THIS AFTERNOON SOUTHERN TWO THIRDS OF SOUTHEAST MI...AND
LEAVE NORTH THIRD DRY...THEN CONTINUE GOING FORECAST OF CHANCE POPS
TONIGHT INTO MID WEEK...WITH COOLER AIR THEN MOVING IN. CURRENT
FORECAST TEMPERATURES CONTINUE TO BE SUPPORTED BY MOS FROM FAVORED
ETA/NGM.

ETA SHOWS MEAGER OMEGA LIFT 850 TO 700 MB THIS AFTERNOON AND
TONIGHT...NGM AS BIT BETTER...THEN MODEST AT TIMES THROUGH TUESDAY
NIGHT. MODEL CONSENSUS SHOWS MODEST 850 TO 500 MB QVECTOR
CONVERGENCE AT TIMES THROUGH TUESDAY NIGHT. SURFACE CONVERGENCE
SLIGHT TO MODEST TONIGHT THROUGH MONDAY WITH SOME SEMBLANCE OF WARM
FRONT THEN COLD FRONT/TROUGH OR TROUGHS. 250 MB/850 MB
DIVERGENCE/CONVERGENCE COUPLING FAIRLY GOOD THIS
AFTERNOON/EVENING...ETA ESPECIALLY SO MONDAY. THERMODYNAMICS FROM
ETA SUPPORT GROWING CHANCE OF THUNDERSTORMS THIS AFTERNOON
ESPECIALLY SOUTH...WANING A BIT TONIGHT AS USUAL AND INCREASING
AGAIN TUESDAY...WITH DAYTIME LIFTED INDICES QUITE UNSTABLE AND MODEL
CAPES ESPECIALLY TUESDAY PUSHING 2000JOULES OR GREATER AND
RESPECTABLE WIND FIELDS SETTING UP TO SUPPORT SOME CHANCE OF SEVERE.

.DTX...NONE.

DWD

EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT
HTTP://WWW.CRH.NOAA.GOV/DTX  (ALL LOWER CASE)

MIZ047>049-053>055-060>063-068>070-075-076-082-083-071200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
245 PM EDT SUN JUL 6 2003

...SEVERE THUNDERSTORM WATCH 655 HAS BEEN ISSUED UNTIL 7 PM FOR AREAS
GENERALLY ALONG AND SOUTH OF I 69...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST LOWER MICHIGAN

.DAY ONE...TODAY AND TONIGHT

SCATTERED THUNDERSTORMS WILL CONTINUE TO DEVELOP ALONG A WARM FRONT
THIS AFTERNOON. A FEW OF THESE STORMS COULD BECOME SEVERE...AND
PRODUCE WIND GUSTS TO 60 MPH AND HAIL THE SIZE OF PENNIES...AS THEY
MOVE EAST AT 15 MPH. THIS ACTIVITY SHOULD REMAIN CONFINED TO AREAS
FROM I 69 SOUTH.

ADDITIONAL THUNDERSTORMS WILL APPROACH THE AREA THIS EVENING AS A
STRONG UPPER LEVEL DISTURBANCE MOVE INTO THE CENTRAL LAKES. THE
CHANCE FOR SEVERE WEATHER WILL BECOME MORE WIDESPREAD THIS EVENING
AS THESE STORMS MOVE INTO THE AREA AT AROUND 30 MPH. AGAIN...LARGE
HAIL AND DAMAGING WINDS WILL BE THE MAIN HAZARDS. ALTHOUGH MOST OF
THIS ACTIVITY WILL OCCUR FROM I 69 SOUTH...A FEW STORMS WILL ALSO
STRAY NORTH INTO THE SAGINAW VALLEY AND THUMB REGION OVERNIGHT.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

A MODERATE CHANCE OF SEVERE THUNDERSTORMS EXISTS FOR ALL OF
SOUTHEAST MICHIGAN MONDAY AND MONDAY NIGHT...AS A COLD FRONT
APPROACHES FROM THE WEST AND THEN PASSES THROUGH. DAMAGING WIND
GUSTS AND LARGE HAIL ARE AGAIN POSSIBLE...ALONG WITH ISOLATED
TORNADOES.

MORE SEVERE THUNDERSTORMS ARE POSSIBLE TUESDAY AND TUESDAY
NIGHT...AS A TROUGH LINGERS ACROSS THE AREA.

THE UNSETTLED WEATHER PATTERN WILL THEN CONTINUE INTO THE MID
WEEK...WITH A CHANCE OF THUNDERSTORMS THROUGH WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

DISPATCHERS...PLEASE NOTIFY YOUR EMERGENCY MANAGER IMMEDIATELY.
SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND TONIGHT.

&&

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)

GURNEY