878
FXUS63 KDTX 200652
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
252 AM EDT SUN JUL 20 2025
KEY MESSAGES
- DRY WITH SEASONABLE TEMPERATURES THROUGH TUESDAY.
- HOT AND HUMID WEDNESDAY AND THURSDAY WITH HEAT INDEX APPROACHING
100 DEGREES POSSIBLE ON THURSDAY.
- LOW CHANCE OF SHOWERS AND THUNDERSTORMS NORTH OF I-69
WEDNESDAY. HIGHER AND MORE WIDESPREAD CHANCES THURSDAY AND FRIDAY.
DISCUSSION
WEAK LOW PRESSURE SYSTEM AND COLD FRONT ARE WORKING THROUGH THE STATE
THIS MORNING. AMPLE LOW LEVEL MOISTURE WITH DEWPOINTS TOPPING 70
DEGREES IS SUPPORTING HIGH COVERAGE OF LOW CLOUDS AND ISOLATED SPOTS
PATCHY FOG. COLD FRONT WILL SETTLE SOUTH OF THE STATE TOWARDS THE
END OF THE MORNING AND SETTLE TOWARDS THE OHIO VALLEY FOR THE
AFTERNOON AND EVENING. COMBINATION OF DIURNAL MIXING AND ARRIVAL OF
DRY AIR WILL HELP LIFT LOWER CLOUDS THROUGH THE MORNING, THOUGH THE
COOLER NORTHERLY FLOW SHOULD MAINTAIN A DECENT COVERAGE OF CLOUDS
THROUGH MUCH OF THE DAY. THE INFLUENCE OF A HIGH PRESSURE CENTERED
TOWARDS LAKE SUPERIOR TODAY WILL INCREASE THE STABLE CONDITIONS
LOCALLY AND BRING A MOSTLY DRY FORECAST. THE ONE EXPECTATION MAY BE
ALONG THE SOUTHERN BORDER WHERE SHOWERS AND POSSIBLY A BRIEF
THUNDERSTORM MAY GRAZE THE STATE LINE GIVEN THE PROXIMITY OF THE
FRONT AND CONVECTION BEING SUPPORTED ALONG THE FRONT THROUGHOUT THE
DAY. LOWER POPS UP TO 20 PCT WILL COVER THIS. POST FRONTAL AIRMASS
WILL DROP HIGH TEMPERATURES TODAY BACK DOWN TO THE AVERAGE OR A FEW
DEGREES BELOW (UPPER 70S TO LOW 80S).
THERE WILL BE AN EXPANSION OF THE UPPER LEVEL RIDGE FROM THE
MISSISSIPPI RIVER VALLEY TO THE GREAT LAKES INTO THE MIDDLE OF THE
WEEK WHILE THE SURFACE HIGH PRESSURE SLIDES EAST TUESDAY TOWARDS THE
ATLANTIC. THE RESULT WILL BE A WARMING TREND EARLY TO MID WEEK. THE
INCREASING SOUTH TO SOUTHWEST LOWER LEVEL FLOW WILL USHER IN 850 MB
TEMPERATURES TO 20C OR GREATER BY WEDNESDAY BRINGING HIGHS TO AROUND
90. SOLID MOISTURE ADVECTION WILL ALSO ACCOMPANY THE HEAT WITH
DEWPOINTS INCREASING WELL INTO THE 60S TO 70 DEGREES. THE STRENGTH OF
THE RIDGE SHOULD KEEP MOST OF THE AREA DRY THROUGH WEDNESDAY, THOUGH
LOWER END POPS WILL REMAIN IN THE FORECAST ACROSS THE TRI- CITIES
AND NORTHERN THUMB AS SHORTWAVES TRIGGER A POSSIBLE CONVECTIVE
COMPLEX THAT WILL RIDE THE NORTHERN END OF THE RIDGE AND MAINLY IMPACT
NORTHERN MI AND PARTS OF NORTHERN LOWER MI. ANOTHER HOT AND HUMID
DAY MAY BE IN STORE FOR THURSDAY. HOWEVER, HIGHS INTO THE 90S EACH
DAY WILL ULTIMATELY DEPEND ON WHAT THE OVERALL CLOUD COVER AND
EVOLUTION OF PRECIPITATION ENDS UP BEING GIVEN THE NEARBY CHANCES
WEDNESDAY AND THE MID TO LATE DAY CHANCES ON THURSDAY. THURSDAY INTO
FRIDAY PROSPECTS FOR PRECIPITATION LOOK BETTER AS CANADIAN TROUGHING
WILL DRAW A COLD FRONT TROUGH THE GREAT LAKES AND SHOULD SUPPORT THE
BEST CHANCE FOR RAIN DURING THE WEEK.
MARINE
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE TO
DIMINISH AS THE COLD FRONT PUSHES EAST OF THE REGION EARLY SUNDAY
MORNING. QUIETER MARINE CONDITIONS THEN TAKE OVER BEHIND THE FRONT
GOING THROUGH THE REST OF THE DAY. NORTHERLY WINDS ALSO PREVAIL AS
HIGH PRESSURE BEGINS TO BUILD IN OVER THE AREA. THE HIGH PRESSURE
WILL HOLD ACROSS THE REGION THROUGH MONDAY INTO TUESDAY KEEPING
DRIER CONDITIONS AND LIGHTER WINDS IN PLACE. WINDS SLOWLY VEER TO
THE EAST AS A WARM FRONT LOOK SOT MOVE IN FROM THE MIDWEST. THIS
WILL BRING THE NEXT CHANCES FOR THUNDERSTORMS TUESDAY NIGHT INTO
WEDNESDAY.
PREV DISCUSSION
ISSUED AT 1137 PM EDT SAT JUL 19 2025
AVIATION...
A RATHER COMPLEX CLOUD/FOG SET UP IS EXPECTED OVERNIGHT THROUGH THE
EARLY MORNING HOURS. LIGHT WINDS AMPLE LOW LEVEL MOISTURE, MARKED BY
SFC DEWPOINTS AROUND 70 WILL BE SUPPORTIVE OF THIS LOW CLOUD/FOG
DEVELOPMENT AS THE HIGHER CLOUDS DEPART TO THE EAST. MEANWHILE, A
SLOW MOVING COLD FRONT WILL ADVANCE ACROSS SE MI OVERNIGHT. SHALLOW
POST FRONTAL COLD AIR ADVECTION INTO THE AMBIENT LOW LEVEL MOISTURE
WILL SUPPORT AN EXPANSION OF LOW CLOUDS LASTING THROUGH THE MORNING.
PROBABILISTIC GUIDANCE AND VARIOUS MODEL SOUNDINGS SUGGEST A MIX OF
LOW END MVFR AND IFR BASED CLOUDS THROUGH THE MORNING. DIURNAL
MIXING AND DRY AIR ADVECTION FROM THE NORTH WILL RESULT IN A SUBTLE
EROSION OF EARLY DAY LOW CLOUDS DURING THE LATE AFTERNOON SUNDAY.
FOR DTW/D21 CONVECTION...ALTHOUGH ISOLATED SHOWERS REMAIN POSSIBLE
ALONG THE COLD FRONT EARLY SUNDAY MORNING, THUNDERSTORM
PROBABILITIES ARE LOW.
THRESHOLD PROBABILITIES...
* HIGH IN CEILINGS AOB 5000 FEET OVERNIGHT AND SUNDAY.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
DISCUSSION...AA
MARINE.......TF/SS
AVIATION.....SC
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