810
FXUS63 KDTX 150357
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1157 PM EDT SUN SEP 14 2025
KEY MESSAGES
- PATCHY FOG LATE TONIGHT AND EARLY MORNING WITH AREAS OF FOG ALONG
THE LAKESHORE.
- MUCH ABOVE NORMAL HIGHS WITH CONTINUING DRY WEATHER INTO NEXT WEEK.
AVIATION
NE SURFACE WIND IS SHOWING SOME TENDENCY TO HOLD NEAR 5 KNOTS SINCE
SUNSET, LESS AT DTW AND MORE TOWARD MBS WHERE REINFORCEMENT OF THE
SAGINAW BAY MARINE LAYER IS EVIDENT. THIS IS OCCURRING UNDER CLEAR
SKY TO MAINTAIN A FAVORABLE SETUP FOR RADIATIONAL COOLING AND FOG
AND/OR STRATUS LATE TONIGHT AND EARLY MORNING. THERE ARE HINTS OF
LIFR STRATUS FARTHER NORTH TOWARD OSC, ON THE EDGE OF A LARGER MID
CLOUD AREA OVER INTERIOR NORTHERN LOWER MI. THE OSC CLOUD TRENDS
LEAN THE MBS FORECAST IN THAT DIRECTION AND MORE TOWARD MVFR FOG IN
THE FNT TO PTK AREA, IFR IF THE WIND DROPS OFF LATE. THE NE
DIRECTION IS MORE OF A LIMITING FACTOR FOR BOTH CLOUDS AND FOG AT
DTW, AT LEAST INITIALLY AS LAKE ERIE OBSERVATIONS ARE CONVINCINGLY
NE AT FORECAST ISSUANCE. THERE IS A LATE DEVELOPING VEERING TREND IN
MODEL GUIDANCE FOR THE DTW CORRIDOR TOWARD SUNRISE BUT WITH LOW
PREDICTABILITY ON FOG/STRATUS OUTCOMES AS A RESULT. THE MORNING THEN
STARTS OFF WITH FULL SUN TO ENSURE A STANDARD MID SEPTEMBER PACE OF
FOG/STRATUS DISSIPATION LEADING INTO ANOTHER AFTERNOON OF JUST FAIR
WEATHER CUMULUS THAT LINGERS INTO MONDAY EVENING.
FOR DTW/D21 CONVECTION... NO THUNDERSTORMS THROUGH THE EARLY WEEK
PERIOD.
THRESHOLD PROBABILITIES...
* LOW FOR CEILING AT OR BELOW 200 FT, OR VISIBILITY BELOW 1/2 SM
EARLY IN THE MORNING.
PREV DISCUSSION
ISSUED AT 317 PM EDT SUN SEP 14 2025
DISCUSSION...
SURFACE HIGH PRESSURE AND BUILDING UPPER LEVEL HEIGHTS WILL GOVERN
CONDITIONS ACROSS SE MICHIGAN OVER THE NEXT SEVERAL DAYS. THE 12Z
KDTX RAOB DEPICTS A VERY DRY AIRMASS ALOFT, WITH 700-600MB LAYER
DEWPOINT DEPRESSIONS NEAR 40 C. LAKE MOISTURE HAS PROVEN NECESSARY
FOR DIURNAL CU DEVELOPMENT, WITH THE CU FIELD HUGGING THE EDGE OF THE
MARINE LAYER. DEWPOINTS CURRENTLY IN THE MID-50S ARE NEARLY
IDENTICAL TO CROSSOVER TEMPERATURES FROM YESTERDAY WITH SIMILARLY
FAVORABLE RADIATIONAL COOLING POTENTIAL TO SUPPORT PATCHY TO AREAS OF
FOG MONDAY MORNING. THIS PATTERN HOLDS IN PLACE THROUGH AT LEAST
MID-WEEK AS THE UPPER RIDGE TRANSITIONS TO A REX BLOCKING PATTERN.
TEMPERATURES MAY CLIMB A DEGREE OR TWO EACH DAY DUE TO AIRMASS
MODIFICATION, ALTHOUGH THE WARMEST DAY IS ANTICIPATED TO BE THURSDAY
WHEN WINDS SHIFT TO THE SOUTHWEST AND KICK OFF MODEST WARM ADVECTION.
UPSTREAM, MID-LEVEL WV DEPICTS TWO SEPARATE TROUGH AXES WITH
EMBEDDED SHORTWAVES: THE FIRST EXTENDING FROM THE PLAINS INTO
ALBERTA, AND THE SECOND ONSHORE THE PACIFIC COAST. DETERMINISTIC
MODELS HAVE STARTED TO CONVERGE ON THE SOLUTION THAT KEEPS THESE
TROUGHS OUT OF PHASE THROUGH THE FIRST HALF OF THE WEEK, BUT THEY
WILL DISLODGE/WEAKEN THE UPPER RIDGE AS THEY PIVOT TO THE NORTH.
EVENTUALLY, THE TRAILING TROUGH IS EXPECTED TO EVOLVE INTO AN UPPER
LOW AND SETTLE INTO THE PLAINS. THIS SYSTEM WOULD BEGIN TO INFLUENCE
THE GREAT LAKES FRIDAY-THIS WEEKEND, ALTHOUGH ENSEMBLE MEMBERS STILL
SHOW QUITE A BIT OF VARIABILITY DUE TO UNCERTAIN INTERFERENCE
BETWEEN THE MULTIPLE WAVES. IN GENERAL, THE EXPECTATION IS A SHIFT
TOWARD A WETTER PATTERN FOR THE WEEKEND.
MARINE...
A RIDGE OF HIGH PRESSURE WILL BRING AN EXTENDED PERIOD OF DRY
WEATHER AND LIGHTER WINDS TO THE GREAT LAKES THROUGH THE WEEK. SOME
LOCALIZED HIGHER WIND SPEEDS NEARING 15 TO 20 KNOTS WILL BE POSSIBLE
INTO THE SAGINAW BAY THIS AFTERNOON AND EVENING AND AGAIN TOMORROW
AFTERNOON AND EVENING GIVEN THE FAVORABLE NORTHEAST FETCH.
OTHERWISE, THE NEXT CHANCE FOR MORE ACTIVE WEATHER WILL ENTER NEXT
WEEKEND AS A LOW PRESSURE SYSTEM NEARS THE REGION.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....BT
DISCUSSION...MV
MARINE.......AM
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AT WWW.WEATHER.GOV/DETROIT.
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