380
FXUS63 KDTX 211915
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
315 PM EDT MON APR 21 2025
KEY MESSAGES
- WINDY THIS AFTERNOON WITH SOUTHWEST GUSTS AROUND 45 MPH,
DIMINISHING THIS EVENING.
- COOLER TUESDAY, BUT TEMPS BACK UP INTO THE 70S WEDNESDAY-FRIDAY.
- WIDESPREAD RAIN EXPECTED TO RETURN FOR FRIDAY.
DISCUSSION
MATURE LOW PRESSURE (~1000 MB) SYSTEM EXITING NORTHEAST OF THE
NORTHERN GREAT LAKES THIS EVENING. SOUTHWEST WIND GUSTS BEHIND THE
FROPA DID PEAK OUT IN THE 40-50 MPH RANGE ACROSS SOUTHEAST MICHIGAN,
ESPECIALLY AND INCLUDING SOUTH OF M-59, AS MAX TEMPERATURES REACHED
INTO UPPER 60S TO MID 70S. STILL 45-50 KNOTS OF FLOW AT THE 850 MB
LEVEL ACROSS THE NORTHERN HALF OF THE CWA, AND WILL THUS MAINTAIN THE
WIND ADVISORY FOR NOW, ALTHOUGH GUSTS TO 45 MPH WILL LIKELY BE
SPORADIC. THE NORTHERN TIP OF THE THUMB REGION FINALLY LOOKS TO GET
INTO THE ACTION AND SEE THE MORE FREQUENT/PEAK WINDS AS WINDS VEER
AROUND TO THE WEST. WINDS TO DIMINISH THIS EVENING AND TONIGHT, BUT
WINDS STILL HOLDING AROUND 10 MPH TOWARD SUNRISE TUESDAY. THUS, EVEN
WITH CLOUDS SLOWLY DISSIPATING, SHOULD NOT HAVE TO WORRY ABOUT FROST
AS TEMPS DIP INTO THE UPPER 30S TO AROUND 40 DEGREES.
MORE DISORGANIZED, BUT ABUNDANT UPPER LEVEL PV/ENERGY BACK ACROSS
THE NORTHERN ROCKIES, WHICH WILL SPIN UP A WEAK LOW/REFLECTION IN
THE UPPER MISSISSIPPI RIVER VALLEY/MIDWEST COME TUESDAY. SURFACE
FRONTAL BOUNDARY/INCREASING MOISTURE LOOKS TO REACH THE SOUTHERN
MICHIGAN BORDER TOWARD 00Z WEDNESDAY, AND THERE MAY BE ENOUGH MID
LEVEL INSTABILITY TO ALLOW FOR SHOWERS AND EVEN AN ISOLATED
THUNDERSTORM SURVIVE THE TRIP INTO SOUTHEAST MICHIGAN BY TUESDAY
EVENING. MID LEVEL LAPSE RATES ARE STEEP, GREATER THAN 7 C/KM.
HOWEVER, THE LOW INSTABILITY (MUCAPES ~1000 J/KG) RESERVOIR SHOULD
MOSTLY HOLD OVER THE WESTERN GREAT LAKES THROUGH TUESDAY NIGHT. STILL,
12Z HRRR SUGGESTS WEST TO EAST TRAINING OF CONVECTIVE ACTIVITY IS
POSSIBLE WITH THE MODEST WESTERLY LOW LEVEL JET.
MODEST SFC-850 MB BASED INSTABILITY/CAPE DEVELOPING DURING WEDNESDAY
SOUTH OF I-69 MAY TOUCH OFF SCATTERED SHOWERS/ISOLATED THUNDERSTORMS
WITH WEAK LOW LEVEL CONVERGENCE, LEFTOVER FRONTAL BOUNDARY. HOWEVER,
MODEST HEIGHT RISES (500 MB HEIGHTS OF 573+ DAM) AND SOME SEMBLANCE
OF 500 MB RIDGE AXIS BUILDING OVER THE CENTRAL GREAT LAKES,
PROMOTING GENERAL SUBSIDENCE, LEADS TO LOW CONFIDENCE. NBM POPS LOOK
OK WITH MOSTLY SLIGHT CHANCE (15-25).
FURTHER HEIGHT RISES FOR THURSDAY, BUT POTENTIAL SHORTWAVE COMING
OUT OF THE MIDWEST TO END THE WORK WEEK, MERGING WITH A NORTHERN
STREAM TROUGH TRACKING OUT OF SOUTH CENTRAL CANADA. CYCLOGENSIS
TAKING PLACE OVER THE WESTERN OHIO VALLEY BY FRIDAY SHOULD SUPPORT
WIDESPREAD RAIN OVERSPREADING SOUTHEAST MICHIGAN, WITH THE LOW ON
PACE TO EXIT EAST ON SATURDAY. ANY RESIDUAL LIGHT RAIN ENDING EARLY
IN THE MORNING, WITH DRY CONDITIONS THEN IN PLACE FOR THE REST OF
THE WEEKEND, PER 12Z EURO.
MARINE
SHALLOW MIXING DEPTHS IN THE WAKE OF A COLD FRONT WILL CONTINUE TO
INTERACT WITH A SHALLOW YET STRONG WIND FIELD ALOFT, BRINGING GUSTS
TO GALES FOR THE MAJORITY OF THE NEARSHORE ZONES OUTSIDE OF WESTERN
LAKE ERIE. SOME SPORADIC GUSTS TO GALES REMAIN POSSIBLE FOR WESTERN
LAKE ERIE, BUT LATEST OBSERVATIONS PRECLUDE THE ISSUANCE OF ANY
SHORT-FUSED WARNING PRODUCT, WITH EXPECTATION THAT GALES FOR ALL
NEARSHORE ZONES DIMINISH BY LATE THIS EVENING. FOR LAKE HURON,
PASSAGE OF A LOW PRESSURE SYSTEM WILL VEER WIND DIRECTION FROM THE
WEST WITH COOLER AIR FILTERING IN ALOFT, WHICH WILL THEN PIVOT THE
GALE THREAT TO THE NORTHERN THIRD OF LAKE HURON OVERNIGHT. A RIDGE
OF HIGH PRESSURE WILL BUILD IN THROUGH TUESDAY AFTERNOON,
DIMINISHING WIND SPEEDS THROUGH THE DAY TOMORROW. LIGHT WINDS THEN
CONTINUE THROUGH THE MIDWEEK PERIOD AS THE PRESSURE GRADIENT REMAINS
WEAK.
PREV DISCUSSION
ISSUED AT 113 PM EDT MON APR 21 2025
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.
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.
DISCUSSION...SF
MARINE.......AM
AVIATION.....BT
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