147
FXUS63 KDTX 092321
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
721 PM EDT TUE SEP 9 2025
KEY MESSAGES
- PLEASANT, DRY SEPTEMBER WEATHER THROUGH FRIDAY.
AVIATION
HIGH PRESSURE CONTINUES TO RESULT IN VFR CONDITIONS WITH PERIODIC
HIGH BASED CIRRUS COVERAGE. LACK OF GRADIENT FLOW WILL TURN WIND
DIRECTION MORE VARIABLE TONIGHT AND OVERNIGHT. THERE REMAINS A WEAK
SIGNAL FOR SOME EARLY MORNING MIFG BETWEEN 10Z-14Z, FAVORED THROUGH
THE METRO TERMINALS, BUT A GRADUAL INCREASE IN NOCTURNAL CLOUD
FRACTION SHOULD PREVENT STRONGER RADIATIONAL COOLING.
THRESHOLD PROBABILITIES...
* NONE
PREV DISCUSSION
ISSUED AT 312 PM EDT TUE SEP 9 2025
DISCUSSION...
THE PERSISTENT ELONGATED LOWER TROPOSPHERIC RIDGE ACROSS THE EASTERN
GREAT LAKES HAS PROVIDED ANOTHER DRY DAY WITH AMPLE SUNSHINE ACROSS
SE MI. RADIATIONAL COOLING TONIGHT WITH SFC DEWPOINTS IN THE 40S
WILL RESULT IN ANOTHER SEASONALLY COOL NIGHT, WITH LOWS DROPPING INTO
THE 40S (50S IN URBAN DETROIT). A WEAK MID LEVEL SHORT WAVE NOW OVER
SRN MINNESOTA WILL ROTATE ACROSS LOWER MI WED/WED NIGHT. GIVEN THE
WEAK NATURE OF ASCENT AND FORMIDABLE DRY LAYER NOTED IN THE 850-
600MB LAYER ON MODEL SOUNDINGS, DRY CONDITIONS WILL PREVAIL. RH
PROGS DO HOWEVER SUGGEST AN INCREASE IN HIGH LEVEL CLOUDS,
ESPECIALLY LATE IN THE DAY WEDNESDAY. WEAK SOUTH FLOW IN THE LOW
LEVELS WILL SUSTAIN SLIGHTLY WARMER CONDITIONS EVEN WITH THE HIGH
CLOUDS, WARRANTING HIGH TEMPS FROM THE MID 70S TO AROUND 80. SFC
HIGH PRESSURE WILL STRENGTHEN AND EXPAND FROM NRN ONTARIO ACROSS THE
GREAT LAKES REGION THURSDAY INTO FRIDAY WITHIN BUILDING HEIGHTS
ACROSS THE NRN GREAT LAKES. THE 12Z MODEL SUITE DO NOT REALLY DRIVE
MUCH COOL AIR INTO THE SRN LAKES WITH THIS SYSTEM, WHICH WILL SUPPORT
SEASONALLY WARM TEMPS WITH CONTINUED DRY CONDITIONS.
THERE HAS BEEN VARIABILITY WITHIN THE MODEL SOLUTION SPACE WITH
RESPECT TO THE POTENTIAL LONG WAVE EVOLUTION INTO AN OMEGA BLOCKING
PATTERN THIS WEEKEND INTO EARLY NEXT WEEK. THIS WILL MAINLY INVOLVE
THE TEMPERATURE FORECASTS WITH ENSEMBLE MEMBERS INDICATING MODELS
HAVING DIFFICULTY ON PLACEMENT AND AMPLITUDE OF AN EASTERN CANADIAN
UPPER LOW. THE FORECAST WILL HINGE ON ENSEMBLE MEANS WHICH KEEPS
FORECAST HIGHS ON THE WARM SIDE OF CLIMATOLOGICAL NORMS.
STRENGTHENING LOW LEVEL INFLOW IS FORECAST TO DRIVE A REGION OF MID
LEVEL THETA E ADVECTION/ISENTROPIC ASCENT ACROSS LOWER MI ON
SATURDAY. WHILE THERE ARE DIFFERENCES WITH RESPECT TO PLACEMENT OF
THE STRONGER ASCENT, A CHANCE OF SHOWERS WILL BE WARRANTED IN THE
FORECAST.
MARINE...
QUIET MARINE CONDITIONS PERSIST THROUGH THE EVENING AMIDST DRY
CONDITIONS AND LIGHT SOUTHERLY FLOW. FADING INFLUENCE OF NEW ENGLAND
HIGH PRESSURE ON WEDNESDAY ALLOWS ADDITIONAL RELAXATION OF THE
PRESSURE GRADIENT TO KEEP SUSTAINED WINDS BELOW 10 KNOTS. A WEAK
COLD FRONT OVER LAKE SUPERIOR WILL WASH OUT AS IT DROPS ACROSS LAKE
HURON WEDNESDAY NIGHT-THURSDAY, WITH THE MAIN IMPACT BEING A TREND
TOWARD NORTH/NORTHEAST FLOW. OTHERWISE, ANOTHER AREA OF HIGH
PRESSURE BUILDS FROM QUEBEC TOWARD NEW ENGLAND AFFORDING ANOTHER
EXTENDED STRETCH OF DRY WEATHER THROUGH FRIDAY. THE NEXT CHANCE FOR
RAIN ARRIVES SATURDAY, WITH POTENTIAL FOR AN UPPER LEVEL WAVE TO
CLIP THE GREAT LAKES.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....AM
DISCUSSION...SC
MARINE.......MV
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page