Marine Thunderstorm Winds in Lake St. Clair, June 26, 2002

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