Severe Thunderstorm Warning 124, NWS Detroit, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
700 PM EDT THU JUL 27 2006

.AVIATION...

EXPECT THUNDERSTORMS TO INCREASE IN THE KDTW/KDET FORECAST AREAS
EARLY IN THE FORECAST AS AREA OF THUNDERSTORMS LIFTS/BUILDS IN THIS
DIRECTION IN ADVANCE OF AN APPROACHING SHORTWAVE. NORTHWARD MOVING
OUTFLOW FROM EARLIER CONVECTION IN IL/IN IS ALSO HELPING TO FOCUS
THIS ACTIVITY WHICH IS MOVING INTO RIBBON OF INSTABILITY (2000+ J/KG
SBCAPES ACROSS LOWER MICHIGAN). WILL KEEP SHOWERS IN THE FORECAST
THROUGH 05Z...AND TEMPO IN THUNDERSTORMS FROM 01Z-05Z. A FEW OF
THESE STORMS MAY CLIP KFNT AS WELL...BUT WILL ONLY TEMPO IN AN HOUR
OR TWO TO START THE FORECAST.

OTHERWISE...WITH ABUNDANT LOW LEVEL MOISTURE AND WEAK WINDS (AFTER
THE STORMS PASS)...EXPECT FOG TO DEVELOP...WITH CEILINGS ALSO ON THE
CUSP OF IFR/MVFR. WILL MAINTAIN THE PREVIOUS FORECAST OVERNIGHT AT
THIS TIME. THIS WILL BURN OFF ON FRIDAY...AND WILL TREND IN CLEARING
SKIES AND VFR CONDITIONS BY LATE MORNING.

&&

.PREV DISCUSSION...ISSUED AT 418 PM

SHORT TERM...TONIGHT AND FRIDAY

COMPLEX SURFACE AND UPPER AIR PATTERN OVER THE REGION THIS
AFTERNOON. A TIGHT SURFACE PRESSURE GRADIENT IS IN PLACE OVER THE
OHIO RIVER VALLEY WITH A NUMBER OF SURFACE TROUGHS LOCATED ALONG THE
BOUNDARY FROM MISSOURI TO LOWER MICHIGAN. WATER VAPOR IMAGERY SHOWS
A SHORTWAVE MOVING FROM THE UPPER MIDWEST INTO THE CENTRAL GREAT
LAKES WITH A PLUME OF MID LEVEL MOISTURE HEADING TOWARDS SOUTHERN
MICHIGAN. THE MORNING SOUNDING OUT OF LINCOLN ILLINOIS HAD A PW OF
1.88 INCHES WHICH IS REPRESENTATIVE OF THE ATMOSPHERE THAT WILL BE
MOVING OVER SOUTHERN MICHIGAN THIS AFTERNOON AND EVENING. ABUNDANT
CLOUD COVER TODAY HAS LIMITED INSTABILITY A BIT BUT DEWPOINTS IN THE
LOW 70S STILL YIELD UP TO 2500 J/KG OF SURFACE BASED CAPE OVER
SOUTHEAST LOWER. MID LEVEL INSTABILITY IS NOT IMPRESSIVE THOUGH WITH
500MB TEMPS OF -6C AND LAPSE RATES AROUND 7 C/KM. 0-6 KM BULK SHEAR
IS ONLY AROUND 20 KNOTS AND FREEZING LEVELS AROUND 16000 FEET.
ALTHOUGH AN ISOLATED SEVERE STORM CANNOT BE RULED OUT WITH GOOD
PRECIP LOADING...THINK A GREATER CONCERN FOR THIS EVENING WILL BE
HEAVY RAIN. THE TWO MAIN FEATURES TO WATCH FOR CONVECTION TONIGHT
ARE THE SURFACE TROUGH OVER THE SOUTHERN ILLINOIS/INDIANA BORDER AS
IT COLLIDES WITH THE SHORTWAVE DROPPING DOWN FROM THE NORTH. STORM
MOTION IS ONLY EXPECTED TO BE AROUND 15 MPH TO THE EAST NORTHEAST.
THIS FLOW WILL GENERALLY BE LINED UP PARALLEL TO THE BOUNDARY SO
SOME TRAINING OF STORMS IS POSSIBLE...ESPECIALLY ALONG AND SOUTH OF
M-59. AS THESE TWO FEATURES COLLIDE WE COULD SEE A BAND OF
THUNDERSTORMS PRODUCE UP TO 2 TO 3 INCHES OF RAIN BUT DO NOT EXPECT
THIS TO BE WIDESPREAD. SOME LOCALLY HEAVY RAIN COULD PRODUCE MINOR
FLOODING THOUGH AND WILL HAVE TO CLOSELY MONITOR THE GREATER DETROIT
AREA THAT RECEIVED HEAVY RAIN ON WEDNESDAY EVENING.

AS THE RAIN ENDS FROM NORTH TO SOUTH OVERNIGHT...SKIES ARE EXPECTED
TO GRADUALLY CLEAR ACROSS THE NORTHERN COUNTIES. LINGERING LOW LEVEL
MOISTURE WILL LEAD TO AREAS OF FOG AGAIN OVERNIGHT BUT WILL
DISSIPATE EARLY ON FRIDAY MORNING. DRIER AIR ADVECTING FROM THE
NORTH WILL LEAD TO ONLY SCATTERED CLOUDS IN THE NORTH WITH SCT-BKN
SKIES IN THE SOUTH. WILL CONTINUE WITH A LOW CHANCE OF THUNDERSTORMS
ACROSS OUR SOUTHERN COUNTIES THROUGH FRIDAY AS THE BOUNDARY IS SLOW
TO CLEAR THE ENTIRE STATE.

LONG TERM...FRIDAY NIGHT THROUGH THURSDAY

FRIDAY NIGHT AND SATURDAY...

SURFACE FRONT SAGGING SOUTHWARD FROM THE NORTHERN GREAT LAKES REGION
TO APPROACH OR ENTER FORECAST AREA SATURDAY AS PER 12Z NAM AND
00Z/12Z WRFHEMI...WITH GFS MORE RELUCTANT TO DO SO. GENERALLY AM
PREFERRING GFS SOLUTION GIVEN ITS RECENT CONSISTENCY. AT 500
MB...NORTHWEST FLOW WITH EMBEDDED SHORTWAVE TROUGH IMPULSES FOR THIS
PERIOD.

850 TO 500 MB MOISTURE ON THE INCREASE MAINLY NORTH LATE FRIDAY
NIGHT...BECOMING MODEST OVER MOST OF THE AREA SATURDAY. 925 MB
MOISTURE MODEST AT BEST AND MAINLY SATURDAY...WITH GFS CONSIDERABLY
MORE ROBUST THAN NAM.

OCCASIONAL MODEST OMEGA ASCENT FRIDAY NIGHT AND SATURDAY...GENERALLY
BELOW 5 UBAR/SEC. ALSO...SLIGHT 850 TO 500 MB QVECTOR
CONVERGENCE/IMPLIED LIFT SEEN ALONG WITH WEAK LOW LEVEL CONVERGENCE.

VERY LIMITED INSTABILITY WANING EARLY FRIDAY EVENING AS INHIBITION
INCREASES STEADILY...SO WILL KEEP FORECAST DRY FOR NOW. WILL ALSO
KEEP LATE NIGHT MENTION FAR NORTHERN COUNTIES AS MOISTURE/DYNAMICS
INCREASE AHEAD OF THE SAGGING COLD FRONT. QUITE UNSTABLE AND RATHER
UNCAPPED THROUGHOUT SATURDAY TO WARRANT CHANCE SHOWER/THUNDER
MENTION. LIFTED INDICES SATURDAY BECOMING MINUS 5 TO 7 DEGREES
CELSIUS...CAPES GENERALLY 2K JOULES...AND 850 TO 500 MB LAPSE RATES
6 TO 7 DEGREES C/KM. ZERO TO 6 KM BULK SHEAR SATURDAY RELATIVELY
WEAK...MAINLY BELOW 30 KNOTS...SO SEVERE POTENTIAL WILL BE LIMITED.

FROM SATURDAY NIGHT ON...
00Z AND 12Z OPERATIONAL GFS PRETTY MUCH KEEP WAVY SURFACE FRONT
NORTH OF FORECAST AREA SATURDAY NIGHT AND SUNDAY...UNLIKE THE
00Z/12Z WRFHEMI...AND ALSO SOMEWHAT SUPPORTED BY GFS ENSEMBLE MEAN.
OTHERWISE...SOMEWHAT OF A MODEL CONSENSUS SUPPORTING A PREVAILING
BROAD SURFACE RIDGE EXTENDING NORTH ACROSS SOUTHEAST MI INTO THE
MIDDLE PART OF NEXT WEEK...WITH RESULTING SUSTAINED PERIOD OF HEAT
AND HUMIDITY OVER THE AREA. THE 00Z AND 12Z GFS/06Z DGEX BRING IN
COLD FRONT WEDNESDAY...SOME SUPPORT PROVIDED BY THE CANADIAN GLOBAL
AND 00Z ECMWF...THOUGH THE 00Z WRFHEMI WAS ABOUT A DAY EARLIER IN
BRINGING IN THE COLD FRONT. AVAILABLE MODEL DATA THEN BUILDS IN HIGH
PRESSURE BY THURSDAY...USHERING IN TREND TOWARD COOLER WITH LESS
HUMID CONDITIONS.

AT 500 MB...MODELS AGAIN TODAY SHOW A GRADUAL PROGRESSION EASTWARD
OF RIDGE FROM THE NORTHERN PLAINS INTO THE GREAT LAKES THIS WEEKEND
AND RESIDING OVERHEAD UNTIL MID PART OF NEXT WEEK...AT WHICH TIME
CONSENSUS BRINGS IN WELL DEFINED SHORTWAVE TROUGH.

AS WAS THE CASE YESTERDAY...MODELS DEPICT 850 MB TEMPERATURES OF 20
DEGREES CELSIUS PLUS FOR MOST OF EARLY NEXT WEEK...WITH 700 MB
TEMPERATURES 10 TO 12 DEGREES C. VERY LITTLE CHANGES MADE TO THE
PREVIOUS FORECAST FOR THIS TIME PERIOD. EARLY PART OF NEXT
WEEK...WITH HIGH 500 MB HEIGHTS AND WARM TEMPERATURES ALOFT...FAVOR
OVERALL RELATIVELY DRY AIR MASS AND CAPPED ENVIRONMENT FOR
CONVECTION.

LATER FORECASTS MAY HAVE TO DEAL WITH POTENTIAL HEAT ADVISORY
CONDITIONS BY MONDAY.

&&

.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MI WATERS OF LAKE ERIE...NONE.

&&

AVIATION.....DG
SHORT TERM...KAHL
LONG TERM....DWD

YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
454 PM EDT THU JUL 27 2006

CORRECTED TO ADD MENTION OF POTENTIAL HEAT ADVISORY

MIZ047>049-053>055-281000-
MIDLAND-BAY-HURON-SAGINAW-TUSCOLA-SANILAC-
454 PM EDT THU JUL 27 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH PORTIONS OF SOUTHEAST
MICHIGAN.

.DAY ONE...TONIGHT

SCATTERED THUNDERSTORMS ARE EXPECTED UNTIL AROUND 2 AM FRIDAY.
SEVERE WEATHER IS NOT EXPECTED WITH THESE STORMS. THE STRONGEST
STORMS WILL...HOWEVER...BE CAPABLE OF PRODUCING WIND GUSTS TO 20
MPH...FREQUENT LIGHTNING AND HEAVY RAIN. STORMS WILL MOVE TO THE
EAST AT 15 MPH. BECAUSE OF THIS SLOW MOVEMENT...SOME LOCALIZED
FLOODING IS POSSIBLE...MAINLY IN MORE URBANIZED AREAS.

WEAK LOW PRESSURE OVER THE AREA...ALONG WITH AN UNSTABLE AIR
MASS...WILL TRIGGER SCATTERED THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THERE IS A CHANCE OF THUNDERSTORMS BY SATURDAY AND CONTINUING THROUGH
THE WEEKEND. THE COMBINATION OF SEVERAL UPPER LEVEL DISTURBANCES
ALONG WITH A NEARLY STATIONARY FRONT OVER THE GREAT LAKES WILL
PROVIDE THE TRIGGER FOR THESE THUNDERSTORMS.

HOT AND HUMID WEATHER CONDITIONS IN ADVANCE OF A MID WEEK COLD FRONT
WILL LIKELY ALLOW HEAT INDICES TO REACH OR EXCEED 100 DEGREES FOR
BOTH MONDAY AND TUESDAY. THIS MAY NECESSITATE THE ISSUANCE OF A HEAT
ADVISORY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TONIGHT.

MIZ060>063-068>070-075-076-082-083-281000-
SHIAWASSEE-GENESEE-LAPEER-ST. CLAIR-LIVINGSTON-OAKLAND-MACOMB-
WASHTENAW-WAYNE-LENAWEE-MONROE-
454 PM EDT THU JUL 27 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL AND SOUTHERN PORTIONS
OF SOUTHEAST MICHIGAN.

.DAY ONE...TONIGHT

SCATTERED THUNDERSTORMS ARE EXPECTED TONIGHT. SEVERE WEATHER IS
NOT EXPECTED WITH THESE STORMS. THE STRONGEST STORMS
WILL...HOWEVER...BE CAPABLE OF PRODUCING WIND GUSTS TO 20
MPH...FREQUENT LIGHTNING AND HEAVY RAIN. STORMS WILL MOVE TO THE
EAST AT 15 MPH. BECAUSE OF THIS SLOW MOVEMENT...SOME LOCALIZED
FLOODING IS POSSIBLE...MAINLY IN MORE URBANIZED AREAS.

WEAK LOW PRESSURE OVER THE AREA...ALONG WITH AN UNSTABLE AIR
MASS...WILL TRIGGER SCATTERED THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THERE IS A CHANCE OF THUNDERSTORMS FRIDAY ALONG AND SOUTH OF AN
ANN ARBOR TO DETROIT LINE...OVER THE ENTIRE AREA SATURDAY AND
SATURDAY NIGHT...AND NORTH OF THE DETROIT AREA SUNDAY. THE
COMBINATION OF SEVERAL UPPER LEVEL DISTURBANCES ALONG WITH A
NEARLY STATIONARY FRONT OVER THE GREAT LAKES WILL PROVIDE THE
TRIGGER FOR THESE THUNDERSTORMS.

HOT AND HUMID WEATHER CONDITIONS IN ADVANCE OF A MID WEEK COLD FRONT
WILL LIKELY ALLOW HEAT INDICES TO REACH OR EXCEED 100 DEGREES FOR
BOTH MONDAY AND TUESDAY. THIS MAY NECESSITATE THE ISSUANCE OF A HEAT
ADVISORY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TONIGHT.

LCZ422-423-460-LEZ444-LHZ421-422-441>443-462>464-281000-
ST. CLAIR RIVER-DETROIT RIVER-LAKE ST. CLAIR-
MICHIGAN WATERS OF LAKE ERIE-OUTER SAGINAW BAY-INNER SAGINAW BAY-
PORT AUSTIN TO HARBOR BEACH MI-HARBOR BEACH TO PORT SANILAC MI-
PORT SANILAC TO PORT HURON MI-
LAKE HURON OFFSHORE BEYOND 5 NM FROM PORT AUSTIN TO HARBOR BEACH MI-
LAKE HURON OFFSHORE BEYOND 5 NM FROM HARBOR BEACH TO PORT SANILAC MI-
LAKE HURON OFFSHORE BEYOND 5 NM FROM PORT SANILAC TO PORT HURON MI-
454 PM EDT THU JUL 27 2006

THIS HAZARDOUS WEATHER OUTLOOK IS FOR LAKE ST CLAIR...THE MICHIGAN
WATERS OF LAKE ERIE AND LAKE HURON.

.DAY ONE...TONIGHT

SCATTERED THUNDERSTORMS ARE EXPECTED TONIGHT. SEVERE WEATHER IS
NOT EXPECTED WITH THESE STORMS. THE STRONGEST STORMS
WILL...HOWEVER...BE CAPABLE OF PRODUCING WIND GUSTS TO 20
KNOTS...FREQUENT LIGHTNING AND HEAVY RAIN. STORMS WILL MOVE TO
THE EAST AT 15 MPH.

WEAK LOW PRESSURE OVER THE AREA...ALONG WITH AN UNSTABLE AIR
MASS...WILL TRIGGER SCATTERED THUNDERSTORMS.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

A CHANCE OF THUNDERSTORMS EXISTS FRIDAY FROM LAKE ST CLAIR
SOUTHWARD.

THERE IS A CHANCE OF THUNDERSTORMS BY SATURDAY AND CONTINUING THROUGH
THE WEEKEND OVER ALL WATERS. THE COMBINATION OF SEVERAL UPPER
LEVEL DISTURBANCES ALONG WITH A NEARLY STATIONARY FRONT OVER THE
GREAT LAKES WILL PROVIDE THE TRIGGER FOR THESE THUNDERSTORMS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TONIGHT.

DWD

YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).