122
FXUS63 KDTX 091632
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1232 PM EDT SAT AUG 9 2025
KEY MESSAGES
- HOT AND MUGGY WEATHER BUILDS IN THIS WEEKEND WITH HEAT INDEX WELL
INTO THE 90S TODAY THROUGH MONDAY.
-DRY OVER THE WEEKEND, WITH A BETTER CHANCE OF SHOWERS AND
THUNDERSTORMS RETURNING EARLY NEXT WEEK.
AVIATION
THE PERSISTENCE OF LOW TO MID LEVEL HIGH PRESSURE ACROSS THE MID
ATLANTIC AND EASTERN GREAT LAKES WILL MAINTAIN STRONG STABILITY
ACROSS SE MI TODAY AND TONIGHT, WHICH WILL INHIBIT LATE DAY
CONVECTIVE DEVELOPMENT. THERE WILL BE ENOUGH LOW LEVEL MOISTURE TO
SUPPORT A SCATTERED DIURNAL CU FIELD. THE SOUTHERLY GRADIENT AND
DAYTIME HEATING WILL SUSTAIN SOUTH WINDS AROUND 10 KNOTS. WINDS WILL
WEAKEN SLIGHTLY WITH THE ONSET OF NIGHTTIME COOLING THIS EVENING.
FOR DTW/D21 CONVECTION... THUNDERSTORMS ARE NOT EXPECTED THROUGH
THE TAF PERIOD.
THRESHOLD PROBABILITIES...
* NONE.
PREV DISCUSSION
ISSUED AT 332 AM EDT SAT AUG 9 2025
DISCUSSION...
FAIRLY QUIET THIS WEEKEND IN TERMS OF CONVECTION AS STRONG RIDGING
PROVIDES A NICE CAP THROUGH SUNDAY AND POSSIBLY SUNDAY NIGHT. THE
UPPER LEVEL TROUGH OVER THE NORTHERN PLAINS WILL SHIFT SLIGHTLY
EASTWARD INTO THE MIDWEST THROUGH THIS TIME WHILE THE 500 MB VORT
MAX AND ATTENDANT SURFACE LOW SHIFT NORTHEAST INTO MANITOBA AND
ONTARIO. THIS WILL DRAW THE COLD FRONT CLOSER TO THE REGION BUT IT
SHOULD STALL FROM THE UP DOWN THROUGH WI AND IA. THE NARROW CORRIDOR
OF THE STRONG LOW LEVEL JET CORE WILL HOLD TO OUR WEST AS WELL
RESULTING IN SEVERAL ROUNDS OF CONVECTION THROUGH THIS TIME. SE MI
WILL BE CAPPED WITH STRONG SOUTHERLY WARM AIR ADVECTION AHEAD OF THE
FRONT. BROAD SURFACE RIDGE OVER THE EASTERN CONUS WILL REMAIN
OVERHEAD WHILE A MIN LEVEL RIDGE STRENGTHENS ALL UNDER THE
AMPLIFIED, POSITIVELY TILTED UPPER LEVEL RIDGE POSITIONED OVER THE
GREAT LAKES. THERE WILL BE PLENTY OF CONVECTION UPSTREAM WHICH WILL
START SPREADING OVER WESTERN AND NORTHERN LOWER SUNDAY AND SUNDAY
NIGHT AS THE COLD FRONT DRIFTS CLOSER, BUT WE MAY STAY DRY THROUGH
THE WEEKEND. WE'LL HAVE TO WATCH TO SEE IF ANY OUTFLOW BOUNDARIES CAN
SPREAD THE CONVECTION FURTHER EAST THAN GUIDANCE SUGGESTS.
A BIGGER CONCERN THIS WEEKEND WILL BE A RETURN OF THE HOT AND HUMID
AIR. 500MB HEIGHTS AROUND 591-593 DAM (CONSISTENTLY OVER THE LAST
COUPLE DAYS) WILL HELP BOOST TEMPS UP A COUPLE DEGREES FROM
YESTERDAYS MID-UPPER 80S LEADING TO WIDESPREAD TEMPS NEAR 90 INTO
THE LOW 90S THROUGH THE SAGINAW VALLEY. DEWPOINTS AROUND 70, COULD
MIX DOWN A LITTLE THIS AFTERNOON, BUT WILL COMBINE WITH THE TEMPS TO
RESULT IN HEAT INDICES IN THE MID 90S. IF DEWPOINTS CAN HOLD UP
AROUND 70S COULD SEE SOME UPPER 90S AT TIMES AS WELL. SIMILAR
SITUATION SUNDAY SO COULD SEE SOME CUMULATIVE EFFECTS OF THE HEAT
PILING UP. COULD ALSO HAVE SOME CLOUDS WORK EAST INTO THE AREA FROM
THE CONVECTION UPSTREAM, THOUGH CONFIDENCE IS LOW IN THIS WITH THE
STOUT RIDGE IN PLACE. HEADLINES ARE NOT EXPECTED TODAY AND WE'LL
MONITOR FOR POSSIBILITY OF ISSUANCE FOR SUNDAY.
SOME 90S COULD STICK AROUND INTO MONDAY BEFORE THE COLD FRONT DRIFTS
EAST AND SETUP UP OVER LOWER MI WHICH WILL LINGER THROUGH MID WEEK.
THIS WILL KNOCK TEMPS DOWN A BIT DUE TO INCREASED CLOUD COVER AND
POSSIBLE ROUNDS OF SHOWERS AND THUNDERSTORMS. SO TEMPS ARE EXPECTED
TO HOLD ABOVE NORMAL THIS WEEK IN THE MID TO UPPER 80S (LOW 80S IS
NORMAL).
MARINE...
QUIETER MARINE CONDITIONS WITH RESPECT TO STORM RETURN OVERNIGHT
UNDER INFLUENCE OF MID-ATLANTIC HIGH PRESSURE, ENSURING SOUTHWEST
FLOW THROUGH THE WEEKEND. MEANWHILE, A STRONG LOW PRESSURE SYSTEM
STALLS OVER MANITOBA AND TRIGGERS NUMEROUS THUNDERSTORM COMPLEXES
WEST OF THE GREAT LAKES. THESE COMPLEXES ARE EXPECTED TO FIZZLE OUT
BY THE TIME THEY REACH LAKE HURON, ALTHOUGH BRIEF WIND SHIFTS AND/OR
AN ISOLATED THUNDERSTORM CANNOT BE ENTIRELY RULED OUT ACROSS
NORTHERN LAKE HURON DURING PEAK HEATING. HIGHER CONFIDENCE IN A DRY
FORECAST EXISTS WITH SOUTHWARD EXTEND AFFORDED BY A STRONG CAPPING
INVERSION. BY EARLY NEXT WEEK, A SECOND LOW DEVELOPS OVER SOUTHERN
ONTARIO AND TRACKS JUST NORTH OF LAKE SUPERIOR, DRAWING A COLD FRONT
THROUGH THE AREA AND CLEARING OUT THE WARM/HUMID AIRMASS MID-WEEK.
SOUTHWEST WINDS SHIFT TO THE NORTHWEST AS A RESULT OF THIS FRONTAL
PASSAGE.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....SC
DISCUSSION...DRK
MARINE.......MV/BT
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