648
FXUS63 KDTX 280356
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1156 PM EDT SUN SEP 27 2026
KEY MESSAGES
- DRY AND PLEASANT WEATHER CONDITIONS WILL PERSIST INTO WEDNESDAY.
- AREAS OF DENSE FOG ARE FORECAST MONDAY AND TUESDAY MORNINGS.
- RAIN CHANCES INCREASE DURING THE LATTER HALF OF NEXT WEEK WITH
COOLER TEMPERATURES EXPECTED.
AVIATION
HIGH AMPLITUDE H3 TO H5 RIDGING WILL REMAIN IN PLACE ACROSS THE
CENTRAL GREAT LAKES THROUGHOUT THE TAF PERIOD. THE HIGH PRESSURE
WILL BE IMMEDIATELY UPSTREAM AS A DIPOLE TO THE CLOSED NORTHEAST
UNITED STATES UPPER LEVEL LOW. ACTIVE SUBSIDENCE BETWEEN 2.0 AND
10.0 KFT AGL WILL HELP FACILITATE DEEP STABILITY. PERSISTENT NORTH
NORTHEASTERLY FLOW TRAJECTORIES OFF OF LAKE HURON WILL BRING THE
POTENTIAL FOR FOG AGAIN MONDAY MORNING. WELL AGREED UPON SIGNAL FOR
BR/FG WITH NAMNEST AND HRRR SURFACE CONDENSATION PRESSURE DEFICITS
AND MOS GUIDANCE.
D21/DTW CONVECTION...NO THUNDERSTORMS FORECAST THROUGH THE TAF
PERIOD.
DTW THRESHOLD PROBABILITIES
* NONE
PREV DISCUSSION
ISSUED AT 300 PM EDT SUN SEP 27 2026
DISCUSSION...
DEEP LAYER SUBSIDENCE ACROSS LOWER MI WILL PERSIST THROUGH TUESDAY
AS A BROAD RIDGE HOLD IN PLACE. THE DEPARTURE OF THE UPPER LOW OVER
THE MID ATLANTIC ACROSS NEW ENGLAND ON TUESDAY AND HEIGHT FALLS
ACROSS THE UPPER MIDWEST WILL ACTUALLY AMPLIFY THE MID LEVEL RIDGE
ACROSS LOWER MI, WHICH WILL ONLY STRENGTHEN THE SUBSIDENCE. FORECAST
MIXING DEPTHS ON MODEL SOUNDINGS AND PROBABILISTIC TEMPERATURE DATA
SUGGEST A CONTINUATION OF AFTERNOON HIGH TEMPERATURES IN THE LOW TO
MID 70S MONDAY AND TUESDAY, WHILE THE LARGE SCALE SUBSIDENCE WILL
SUPPORT ABUNDANT AFTERNOON SUNSHINE. LATE NIGHT AND MORNING FOG WILL
BE THE PRIMARY FORECAST CONCERNS THE NEXT FEW MORNINGS. NNE FLOW OFF
LAKE HURON WILL PERSIST THROUGH TONIGHT. GIVEN THE RESPONSE OFF THE
LAKE THIS MORNING AND CONSIDERING DEWPOINTS ACROSS THE REGION ARE A
FEW DEGREES HIGHER THAN YESTERDAY, ANOTHER STRATUS/FOG PLUME OFF
LAKE HURON AND SAGINAW BAY IS FORECAST TO DEVELOP TONIGHT/MONDAY
MORNING. A LITTLE STRONGER WINDS ATOP THE NOCTURNAL INVERSION AND
SLIGHT BACKING OF THE WINDS TOWARD THE NORTH MAY ADVECT THE
STRATUS/FOG LAYER FARTHER SOUTH INTO METRO DETROIT. THE LOW LEVEL
WIND FIELDS WILL BE MUCH WEAKER MON NIGHT/TUESDAY MORNING AS HIGH
PRESSURE SETTLES OVERHEAD, REDUCING THE RISK OF ADVECTIVE FOG.
HOWEVER, RESIDUAL MOISTURE IN THE NOCTURNAL BOUNDARY LAYER CAPPED BY
IDEAL RADIATIVE COOLING POTENTIAL WILL RAISE THE RISK OF PURE
RADIATION FOG DEVELOPMENT.
PHASING OF A SOUTHERN STREAM LONG WAVE TROUGH WITH THE REMNANTS OF
HURRICANE POLO WILL TRANSPORT A TROPICAL MOISTURE PLUME INTO THE
SOUTHERN AND CENTRAL HIGH PLAINS TUESDAY AND WILL INCREASE MOISTURE
ADVECTION INTO A LOW TO MID LEVEL FRONTAL BOUNDARY FORECAST TO
PROGRESS ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION IN THE
THURSDAY TO FRIDAY TIME FRAME. THE FRONT WILL BE DRIVEN ACROSS THE
REGION IN RESPONSE TO THE NORTHERN STREAM WAVE TRACKING ACROSS NRN
ONTARIO. DIFFERENCES IN AMPLITUDE AND TIMING OF THIS WAVE LEADS TO
LARGE SPREAD AMONG THE MODEL ENSEMBLES IN TIMING THE FRONTAL SYSTEM
ACROSS LOWER MI. TRENDS IN THE LATEST PROBABILISTIC GUIDANCE ARE
SUPPORTING A LATER TIMING, LEADING TO HIGHER CHANCES OF AN ALL OUT
DRY AND WARM DAY WEDNESDAY. THE POTENTIAL FOR GOOD FRONTAL DYNAMICS
WITHIN THE HIGH THETA E AXIS ALONG THE FRONT WILL SUPPORT A GOOD
CHANCE FOR RAIN. WITHIN THE LATEST PROBABILITY SPACE, THAT IS
EXPECTED SOMETIME IN THE THURSDAY TO FRIDAY TIME FRAME. HIGH SPREAD
IN ENSEMBLE 24 HOUR FORECAST QFP VALUES (RANGING ANYWHERE FROM A
QUARTER INCH TO 2 INCHES) IS A RESULT OF THE VARIATION IN ENSEMBLE
MEMBERS AS TO HOW PROGRESSIVE THIS FRONT WILL BE ACROSS THE SOUTHERN
LAKES.
MARINE...
HIGH PRESSURE NOW SITUATED OVER THE GREAT LAKES WILL HOLD THROUGH
TUESDAY. SOME PERIODIC WIND GUST POTENTIAL AROUND 20 KNOTS WILL BE
POSSIBLE ACROSS SOUTHERN LAKE HURON THIS EVENING. OTHERWISE, WIND
GUST POTENTIAL TO OR BELOW 15 KNOTS IS EXPECTED FOR MOST LOCATIONS.
WIND DIRECTION WILL MAINLY HOLD FROM THE NORTH TO NORTHEAST WITH
HIGH PRESSURE IN PLACE. A WARM FRONT WILL THEN MOVE THROUGH ON
TUESDAY WHICH WILL SHIFT WIND DIRECTION FROM THE SOUTH TO SOUTHWEST.
THIS WILL ALSO BRING THE NEXT CHANCE FOR SOME RAIN SHOWERS OR
THUNDERSTORMS WEDNESDAY AND THURSDAY.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....CB
DISCUSSION...SC
MARINE.......AM
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