588
FXUS63 KDTX 220823
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
423 AM EDT TUE JUL 22 2025
KEY MESSAGES
- DRY AND SEASONABLE TEMPERATURES TODAY.
- HEAT AND HUMID INCREASE WEDNESDAY WITH HEAT INDICES IN THE
UPPER 80S TO LOW 90S.
- THURSDAY WILL BE THE HOTTEST DAY OF THE WEEK WITH HEAT INDICES
APPROACHING OR EXCEEDING 100F. SHOWERS AND THUNDERSTORMS ARE ALSO
POSSIBLE, ESPECIALLY OVERNIGHT.
- WARM AND MUGGY CONDITIONS PERSIST FRIDAY WITH ADDITIONAL
SHOWER/STORM CHANCES INTO THE WEEKEND.
DISCUSSION
SURFACE HIGH PRESSURE SLIDES INTO THE EASTERN GREAT LAKES TODAY
WHILE THE CENTRAL CONUS RIDGE AMPLIFIES ACROSS THE MIDWEST/GREAT
LAKES THROUGH MID-WEEK AND SET THE STAGE FOR A NOTABLE WARMING
TREND. SURFACE WINDS WILL ADJUST ACCORDINGLY THIS AFTERNOON AND
BECOME SOUTHEASTERLY. THESE LOWER LEVEL WIND FIELDS OFFER ONE MORE
DAY OF COMFORTABLE DEWPOINTS THAT WILL BE IN THE 50S TODAY WITH MOST
LOCATIONS SEEING DAYTIME HIGHS IN THE UPPER 70S TO LOW 80S. DEEP
LAYER DRY AIR AND RIDGING WILL KEEP THE WEATHER DRY TODAY.
THERMAL RIDGE FOLDS INTO THE CENTRAL GREAT LAKES TOMORROW WITH FLOW
BECOMING MORE SOUTH TO SOUTHWEST. THIS WILL USHER IN HIGHER
DEWPOINTS INTO THE 60S AND THE WARMER 850 MB TEMPERATURES TO NEAR 20C
ARE DRAWN ACROSS SOUTHEAST MICHIGAN. A MUGGY DAY WILL BE IN STORE
WITH HEAT INDICES CLIMBING INTO THE UPPER 80S FOR MOST OF SOUTHEAST
MICHIGAN AND LOW 90S ACHIEVABLE ACROSS THE SAGINAW VALLEY.
CONSENSUS IS STILL TO KEEP SOUTHEAST MICHIGAN FREE OF PRECIPITATION
AS SHORTWAVE ENERGY DIRECTS CONVECTION TO THE NORTH ACROSS NORTHERN
MICHIGAN AND/OR NORTHERN LOWER MICHIGAN.
THURSDAY WILL BE MORE THAN LIKELY BE THE HOTTEST AND MOST HUMID DAY
OF THE WEEK AS 850MB TEMPERATURES CLIMB ABOVE 20C. LATEST GUIDANCE
IS OFFERING DEWPOINTS INTO THE MID 70S, WHICH IS POSSIBLE, BUT TEND
TO BE A LITTLE SKEPTICAL THIS FAR OUT TO ACHIEVE THESE HIGH OF
DEWPOINTS OF 75 TO 76 WHILE ALSO SEEING HIGH TEMPERATURES INTO THE
MID 90S. IF SOUTHEAST MICHIGAN IN FACT DOES SEE SOME OF THESE HIGH
DEWPOINTS, THEN THE HIGH LIKELY BE MORE LOW 90S. FEEL THAT LOWER 70S
DEWPOINTS ARE MORE PLAUSIBLE, ESPECIALLY LOOKING AT CURRENT
OBSERVATIONS ACROSS THE LOWER MIDWEST, WHICH WOULD NEED AN
AGRICULTURAL BOOST. ANOTHER FACTOR TO WATCH OUT FOR WILL BE POSSIBLE
CLOUD COVER NEARBY GIVEN THE NEARBY FRONTAL FEATURES TO OUR NORTH
AND THE ASSOCIATED CONVECTION THAT COULD MESS WITH HIGH TEMPERATURES.
ALL THAT TO SAY, OUTGOING FORECAST WILL CONTINUE TO HIGHLIGHT HEAT
INDICES APPROACHING OR TOPPING 100 DEGREES ON THURSDAY, BUT BELOW
THE 105 DEGREES NEEDED FOR EXTREME HEAT CRITERIA. A HEAT ADVISORY
WILL BE NEEDED IF GREATER CLOUD COVER AND CONVECTION APPEARS LIKE IT
WILL HOLD TO THE NORTH THROUGH THE BULK OF THE DAY.
CANADIAN TROUGHING AND SHORTWAVE FEATURES WILL WORK TO FLATTEN THE
RIDGE INTO THURSDAY EVENING AND OVERNIGHT WHILE SUPPORTING CONVECTION
ALONG A SOUTH SAGGING BOUNDARY. THIS WILL BRING THE HIGHEST CHANCES
FOR SHOWERS AND THUNDERSTORMS AFTER 8 PM ON THURSDAY AND THROUGH
FRIDAY. MUCAPES REMAIN SUPPORTIVE OF THUNDERSTORMS THROUGH THE
THURSDAY OVERNIGHT PERIOD WITH PWAT IN THE 1.75 TO 2.00 INCH RANGE
SUPPORTING HEAVY RAINFALL POTENTIAL. ONLY MINOR RELIEF FROM THE HEAT
AND HUMIDITY ON FRIDAY WITH HIGH TEMPERATURES HOLDING IN THE 80S.
ZONAL FLOW INTO THE WEEKEND WILL CONTINUE TO OFFER AN UNSETTLED
PATTERN WITH SHORTWAVE FEATURES STREAMING IN FROM THE WEST BRINGING
ADDITIONAL CHANCES FOR SHOWERS AND THUNDERSTORMS INTO THE WEEKEND.
MARINE
WINDS SHIFT TO THE SE THIS MORNING AS THE CENTER OF HIGH PRESSURE
SLIDES INTO QUEBEC THOUGH REMAINING LIGHT (LESS THAN 15KTS). LOW
PRESSURE OVER THE NORTHERN PLAINS THEN LIFTS A WARM FRONT THROUGH
THE CENTRAL GREAT LAKES WEDNESDAY. STORM CHANCES LOOK TO BE CONFINED
TO THE NORTHERN HALF OF THE LAKE HURON WEDNESDAY-THURSDAY OWING TO
CLOSER PROXIMITY TO THE LOW. THESE CHANCES THEN EXPAND OVER THE REST
OF THE REGION THURSDAY NIGHT THROUGH LATE WEEK AS THE ATTENDANT COLD
FRONT SAGS THROUGH THE GREAT LAKES.
PREV DISCUSSION
ISSUED AT 1135 PM EDT MON JUL 21 2025
AVIATION...
SEASONALLY STRONG HIGH PRESSURE WILL REMAINED POSITIONED ACROSS THE
EASTERN GREAT LAKES THROUGH THE TAF PERIOD. OTHER THAN SOME PASSING
MID AND HIGH LEVEL CLOUDS, DRY AIR WILL SUSTAIN MAINLY CLEAR SKIES
BELOW 10K FEET. LIGHT EAST-NORTHEAST WINDS TONIGHT WILL VEER TO THE
SOUTHEAST TUESDAY, WITH A SLIGHT INCREASE IN SPEEDS EXPECTED TUES
AFTERNOON DUE TO DIURNAL MIXING. AVAILABLE LOW LEVEL MOISTURE WILL
BE LEAN, BUT MAY BE ENOUGH TO SUPPORT A FEW MVFR BASED DIURNAL CU
TUESDAY AFTERNOON.
FOR DTW/D21 CONVECTION...NO THUNDERSTORMS WILL OCCUR THROUGH THE TAF
PERIOD.
THRESHOLD PROBABILITIES...
* NONE.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
DISCUSSION...AA
MARINE.......KDK
AVIATION.....SC
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