848
FXUS63 KDTX 211713
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
113 PM EDT MON APR 21 2025
KEY MESSAGES
- WINDY THIS AFTERNOON WITH SOUTHWEST GUSTS AROUND 45 MPH.
- WARMER CONDITIONS THROUGH THE MIDWEEK PERIOD.
AVIATION
A POWERFUL LOW PRESSURE OCCLUSION IS IN PROGRESS ACROSS THE GREAT
LAKES BRINGING STRONG SW WIND AS THE HIGHLIGHT FOR SE MI THIS
AFTERNOON. PEAK GUSTS AROUND 40 KTS CONTINUE AS THE OCCLUSION MATURES
AND THE SURFACE FRONT SWEEPS EASTWARD INTO ONTARIO. LOW LEVEL COLD
ADVECTION FOLLOWS INTO THIS EVENING TO MAINTAIN GUSTY CONDITIONS THAT
GRADUALLY BACK OFF OF THE AFTERNOON PEAK. UPSTREAM OBSERVATIONS ALSO
INDICATE MVFR CLOUD CEILING CHURNING UP INTO THE HIGHER END OF THE
RANGE TOWARD MBS AND INTO LOW END VFR TOWARD DTW WITH STRONGER APRIL
DAYTIME HEATING. THESE CLOUDS HOLD UNTIL LATER IN THE NIGHT WHEN HIGH
PRESSURE APPROACHES FROM THE MIDWEST WITH A CLEARING TREND THROUGH
SUNRISE TUESDAY.
FOR DTW... PEAK WSW WIND GUSTS IN THE 40 KT RANGE ARE ASSOCIATED
WITH PASSAGE OF A STRONG OCCLUDED FRONT THIS AFTERNOON. INTENSITY
GRADUALLY SETTLES BACK INTO THE 30 KNOT RANGE BUT THEN HOLDS AFTER
SUNSET AS COLD AIR MAINTAINS A MIXED LAYER THIS EVENING.
DTW THRESHOLD PROBABILITIES
* HIGH FOR CEILING AT OR BELOW 5000 FEET THIS AFTERNOON AND THIS
EVENING.
PREV DISCUSSION
ISSUED AT 1029 AM EDT MON APR 21 2025
UPDATE...
WIND ADVISORY ISSUED FOR TODAY FOR MOST OF SOUTHEAST MICHIGAN.
LOW PRESSURE (~999 MB) ENTERING NORTHERN LAKE MICHIGAN LATE THIS
MORNING, AND WILL CONTINUE TO TRACK OFF TO THE NORTHEAST, GENERALLY
IN A STEADY STATE/SIMILAR PRESSURE. 50 KNOTS OF FLOW IN THE LOW
LEVELS (925-850 MB) WITH INCREASING MIXING DEPTHS TODAY AS COLD
ADVECTION KICKS IN THIS AFTERNOON WILL SUPPORT WIND GUSTS OF 45+ MPH
ACROSS MOST OF SOUTHEAST MICHIGAN, WITH ADDED SUPPORT FROM CURRENT
UPSTREAM OBS. MAIN RISE/FALL PRESSURE COUPLET (>20 MB/6HR) WILL TRACK
ACROSS CENTRAL/NORTHERN LOWER MICHIGAN LATE THIS AFTERNOON, AND THUS
TRI-CITIES SHOULD SEE THE STRONGEST WINDS, POTENTIALLY REACHING 50
MPH WITH THE FAVORABLE SOUTHWEST TRAJECTORY FUNNELING IN SAGINAW
VALLEY. LEFT THE SOUTHERN FOUR CORNERS OUT OF THE ADVISORY, BUT GUSTS
OF 40-45 MPH CAN EXPECTED THERE AS WELL.
PREV DISCUSSION...
ISSUED AT 357 AM EDT MON APR 21 2025
DISCUSSION...
1003 MB SURFACE LOW POSITIONED OVER SOUTHERN WI EARLY THIS MORNING
WILL TRACK TO NEAR EASTERN LAKE SUPERIOR BY EVENING. NARROW AXIS OF
DEEPER MOISTURE ANCHORED ALONG THE INBOUND ASSOCIATED WARM FRONTAL
BOUNDARY ON PACE TO SWEEP ACROSS SOUTHEAST MICHIGAN THROUGH THE
MORNING PERIOD. ASCENT REMAINS SUFFICIENT TO SUPPORT POCKETS OF
SHOWER DEVELOPMENT, WITH A FEW RUMBLES OF THUNDER PLAUSIBLE GIVEN
PRESENCE OF WEAK ELEVATED INSTABILITY. EARLY DAY WARM FRONTAL TIMING
AFFORDS A SHORT WINDOW /15Z-18Z/ OF LOW LEVEL WARM/MOIST ADVECTION,
BEFORE THE TRAILING COLD/OCCLUDING FRONT SWEEPS THROUGH MID-LATE
AFTERNOON. THIS WILL BRING TEMPERATURES INTO THE 60S. MEANINGFUL
SURFACE DESTABILIZATION WILL BE LACKING TO SUPPORT A GREATER
SECONDARY CONVECTIVE RESPONSE, BUT ISOLATED SUB-SEVERE CONVECTION
REMAINS POSSIBLE DURING THIS TIME. NOTABLE INCREASE IN GUST
MAGNITUDE OCCURS WITHIN THE IMMEDIATE WAKE OF THIS FROPA, BACKED BY
A FIRM SOUTHWEST GRADIENT IN EXCESS OF 20 KNOTS AND SOLID A 30-35
KNOTS COMFORTABLY WITHIN THE THE MIXED LAYER. GREATEST MIXING
POTENTIAL OCCURS AS A FEW BREAKS EMERGE IN THE CLOUD INITIALLY
WITHIN THE POST-FRONTAL ENVIRONMENT, BUT THEN BECOMES INCREASINGLY
COMPROMISED AS LOWER CLOUD INCREASES COVERAGE DIURNALLY. THIS
APPEARS TO PLACE A CEILING ON PROSPECTIVE GUST POTENTIAL OVERALL TO
AROUND 45 MPH. GUSTS OF 35 TO 45 MPH WILL REMAIN COMMON THROUGH THE
EVENING HOURS UNDER SUSTAINED COLD AIR ADVECTION, DESPITE PERSIST
LOW STRATUS.
LOWER AMPLITUDE WESTERLY FLOW TO GOVERN CONDITIONS THROUGHOUT THE
MID WEEK PERIOD. GENERAL MID LEVEL SUBSIDENCE ATOP PERVASIVE SURFACE
RIDGING ENSURES BENIGN CONDITIONS TUESDAY, AS THE RESIDENT THERMAL
PROFILE FAVORS TEMPERATURES EDGED ON THE WARMER SIDE OF AVERAGE.
WEAK WARM FRONTAL BOUNDARY LIFTS INTO THE REGION TUE NIGHT,
RESPONDING TO SOME INCREASE IN SOUTHERLY FLOW UPSTREAM AS WEAK
SHORTWAVE ENERGY TRAVERSES THE CENTRAL CONUS. A MODEST INCREASE IN
BOTH MOISTURE QUALITY AND ASCENT IN THE VICINITY OF THIS BOUNDARY
WILL PROVIDE A CHANCE FOR SHOWER DEVELOPMENT OVERNIGHT AND POSSIBLY
INTO EARLY WEDNESDAY. THE ONSHORE FLOW NORTH OF THE BOUNDARY WILL
MAINTAIN NOTABLY COOLER CONDITIONS ACROSS THE EASTERN THUMB, WHILE
SOUTHERN AREAS PUSH TOWARD 70 DEGREES WEDNESDAY. MODERATING THERMAL
PROFILE TAKES AN ADDITIONAL UPWARD STEP THURSDAY AS UPPER HEIGHTS
BUILD. PREVAILING LOW LEVEL SOUTHEAST FLOW MAY OFFER SOME
RESISTANCE, BUT PROJECTED HIGHS NOW TARGETING THE LOW TO MID 70S FOR
ALL LOCATIONS BUT THE EASTERN THUMB.
MARINE...
LOW PRESSURE CURRENTLY OVER WISCONSIN WILL LIFT NORTHEAST TOWARD THE
STRAITS THROUGHOUT THE DAY. SEVERAL ROUNDS OF SHOWERS AND A FEW
EMBEDDED THUNDERSTORMS WILL PERSIST THROUGH THE MORNING HOURS PRIOR
TO THE PASSAGE OF AN OCCLUDED FRONT THIS AFTERNOON. STRONG WARM
ADVECTION WITH THIS SYSTEM KEEPS MAJORITY OF THE WATERWAYS STABLE,
ALTHOUGH THE LAND-LAKE INTERFACE PRESENTS TYPICAL CONCERNS FOR LAND-
BASED GUSTS TO REACH THE SHORELINE. IN THIS CASE, A SHORT-FUSED GALE
WARNING MAY BE NECESSARY IF OBSERVATIONS WARRANT. POTENTIAL FOR A
PERIOD OF MARGINAL GALES WILL EXIST ACROSS SAGINAW BAY LATE THIS
AFTERNOON THROUGH THE EVENING HOURS. A GALE WARNING NOW EXISTS FOR
THIS CORRIDOR, WHILE HIGH-END SMALL CRAFT ADVISORIES CONTINUE
HIGHLIGHT THE SHORT DURATION WITH SPORADIC GUSTS TO GALES ELSEWHERE.
A MORE FAVORABLE SETUP FOR GALES EXISTS DOWNWIND OF THE STRAITS INTO
NORTHERN LAKE HURON EARLY TUESDAY MORNING WHERE COLDER AIR
TEMPERATURES AND NORTHWEST FLOW FUNNEL ALONG THE FETCH. HIGH
PRESSURE BUILDS IN ON TUESDAY TO SUPPORT A MORE BENIGN MID-WEEK
PATTERN.
DTX WATCHES/WARNINGS/ADVISORIES
MI...WIND ADVISORY UNTIL 10 PM EDT THIS EVENING FOR MIZ047>049-053>055-
060>063-068>070.
LAKE HURON...GALE WARNING UNTIL 10 PM EDT THIS EVENING FOR LHZ421-422-441>443.
GALE WARNING FROM 8 PM THIS EVENING TO 10 AM EDT TUESDAY FOR LHZ361-
362.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 10 AM EDT TUESDAY
FOR LHZ421-422-441>443.
LAKE ST CLAIR...GALE WARNING UNTIL 10 PM EDT THIS EVENING FOR LCZ460.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 4 AM EDT TUESDAY
FOR LCZ460.
MICHIGAN WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT TUESDAY FOR LEZ444.
AVIATION.....BT
UPDATE.......SF
DISCUSSION...MR
MARINE.......MV/MR
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT.
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