500
FXUS63 KDTX 152301
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
701 PM EDT FRI AUG 15 2025
KEY MESSAGES
- HEAT AND HUMIDITY RETURN THIS WEEKEND AS HEAT INDICES PEAK IN THE
UPPER 90S SATURDAY AFTERNOON.
- CHANCE OF THUNDERSTORMS SATURDAY THROUGH SUNDAY MORNING WITH AN
ISOLATED SEVERE STORM POSSIBLE SATURDAY AFTERNOON-EVENING.
- COOLER AND LESS HUMID EARLY NEXT WEEK.
AVIATION
ONE MORE QUIET EVENING AS HIGH PRESSURE REMAINS FIRMLY IN CONTROL.
RIBBON OF CUMULUS ALONG THE COMPOSITE LAKE BREEZE BOUNDARY WILL MIX
OUT OVER THE COURSE OF THE NEXT COUPLE OF HOURS LEAVING CLEAR SKIES
AND LIGHT WINDS. CANOPY OF HIGH CLOUDS WILL WASH INTO THE REGION
OVERNIGHT - COURTESY OF ONGOING DEEP CONVECTION OVER THE UPPER
MISSISSIPPI VALLEY REGION.
THE FORCING RESPONSIBLE FOR THIS ACTIVITY WILL SLOWLY MARCH EAST
INTO THE CENTRAL GREAT LAKES REGION ON SATURDAY. INCREASING BOUNDARY
LAYER MOISTURE AND ACCOMPANYING INSTABILITY WILL SUPPORT GREATER
CUMULUS COVERAGE AND EVENTUALLY SHOWER AND THUNDERSTORM DEVELOPMENT
AND/OR MAINTENANCE OF UPSTREAM ACTIVITY DEVELOPING OVER THE
CORNBELT. TIMING OF ACTIVITY WILL BE A BIT TENUOUS, OUTSIDE THE
GREATER CERTAINTY OF INSTABILITY INCREASING IN DEPTH AND QUALITY
DURING THE MID-LATE AFTERNOON HOURS. AS SUCH WILL ADVERTISE
CONVECTIVE CHANCES INCREASING FROM SOUTH TO NORTH AFTER 20Z
SATURDAY. PLENTY OF OPPORTUNITY FOR REFINEMENT AS MUCH OF THE
FORECAST HINGES ON EVOLUTION OF THE 3-4 CONVECTIVE COMPLEXES
UPSTREAM.
FOR DTW/D21 CONVECTION...CURRENT TIMING ESTIMATES SUPPORT A GOOD
CHANCE FOR THUNDERSTORMS AFTER 22Z SATURDAY ACROSS THE NORTHERN
PORTIONS OF THE D21 AIRSPACE WITH CHANCES INCREASING AFTER 00Z
SUNDAY ACROSS THE CENTRAL AND SOUTHERN PORTIONS.
THRESHOLD PROBABILITIES...
* MEDIUM FOR CEILING AT OR BELOW 5 KFT SATURDAY AFTERNOON.
* MEDIUM FOR THUNDERSTORMS SATURDAY EVENING - MAINLY AFTER 00Z.
PREV DISCUSSION
ISSUED AT 318 PM EDT FRI AUG 15 2025
DISCUSSION...
SE MI REMAINS UNDER THE WESTERN EDGE OF BROAD SURFACE HIGH PRESSURE
CENTERED OVER WESTERN QUEBEC WITH A PASSING MID-LEVEL TROUGH
SUPPORTING TRANSIENT AREAS OF STRATOCUMULUS ATOP DIURNAL CUMULUS.
AMPLE RESULTANT INSOLATION HAS BROUGHT A RETURN OF HIGHS BACK IN THE
MID-UPPER 80S.
INFLUENCE OF SAID HIGH WANES THROUGH THE NIGHT ALLOWING
SOUTHWESTERLY LOW LEVEL RETURN FLOW TO DEVELOP. THIS DRAWS A PIECE
OF THE UPPER PLAINS AIRMASS INTO THE CENTRAL GREAT LAKES PUSHING
850MB TEMPS WELL INTO THE UPPER TEENS (C) AND HIGHS NEAR 90 AS
SURFACE DEWPOINTS EXCEED 70F. RAIN CHANCES SATURDAY ARE DEPENDENT ON
THE PROGRESSION OF UPSTREAM CONVECTION OVER THE UPPER MIDWEST WHICH
LEADS TO INHERENT LOW PREDICTABILITY/HIGH UNCERTAINTY. A SERIES OF
PV ANOMALIES ARE EXPECTED TO GENERATE NOCTURNAL MCS(S) OVER THE
UPPER MIDWEST/PLAINS THOUGH CAMS ARE STRUGGLING TO HANDLE
INITIATION, PARTICULARLY WITH THE LEAD WAVE OVER THE UPPER
MISSISSIPPI VALLEY. SOME SOLUTIONS LIKE THE HRDPS OR NAM NEST ARE
MORE AGGRESSIVE AT A TRUE MCS TO DEVELOP AND DRIFT SOUTHEASTERLY
TOWARDS SOUTHERN LAKE MICHIGAN/FAR SW LOWER MI GIVEN THE INSTABILITY
GRADIENT AND SOUTHERLY INFLOW WINDS. THESE OUTCOMES WOULD HAVE THE
LARGEST POTENTIAL IMPACT ON LATER DAY CONVECTIVE CHANCES LOCALLY AS
MORE CLOUD DEBRIS WORKS ACROSS SOUTHERN LOWER MI LEADING TO MORE
DIFFERENTIAL HEATING OR, IN THE CASE OF THE NEST, THE REMNANT MCV
SPARKS EARLIER DAY CONVECTION (BY EARLY AFTERNOON). CONVERSELY
OTHERS LIKE THE HRRR/RAP FAIL TO SUFFICIENTLY ORGANIZE LEADING TO
MORE SCATTERED CONVECTION AND LITTLE IMPACTS LOCALLY. MORE CONSENSUS
ON THE SECOND WAVE ROUNDING THE RIDGE INTO LOWER MI BY SATURDAY
AFTERNOON. WHILE EXACTLY HOW MUCH OF THE PRIOR NOCTURNAL CONVECTION
TIED TO THIS WAVE SURVIVES INTO MI IS UNCLEAR, WITH THE INITIAL WAVE
TRACK FAVORED TO OUR SOUTHWEST, MLCAPE WOULD BE ABLE TO BUILD TO
AROUND 1500 J/KG ACROSS SE MI BY TIME OF ARRIVAL. THIS WOULD BE MORE
THAN ENOUGH TO ALLOW FOR LOCAL INITIATION AND/OR RE-INVIGORATION OF
ANYTHING STILL ONGOING FROM WEST MI. A FEW STRONG CELLS CAPABLE OF
DAMAGING WIND GUSTS ARE STILL VERY MUCH IN PLAY AS MID LEVEL WINDS
INCREASE WITH THE WAVE ALLOWING FOR GREATER ORGANIZATION POTENTIAL
IN ADDITION TO WELL-MIXED BOUNDARY LAYERS YIELDING DCAPES OVER 1000
J/KG. ALL OF SE MI HAS BEEN ADDED TO A DAY 2 MARGINAL RISK BY SPC.
COLD FRONT THEN SAGS INTO SOUTHERN LOWER MI SUNDAY. LATEST
DETERMINISTIC RUNS HAVE BEGUN TO CONVERGE ON THIS BOUNDARY STALLING
OUT OVER THE REGION OFFERING LINGERING SHOWER/STORM CHANCES DURING
SUNDAY. ANOTHER SHORTWAVE DROPS OUT OF THE UPPER MIDWEST ALONG THIS
BOUNDARY MONDAY-TUESDAY KEEPING UNSETTLED WEATHER LIKELY FOR THE
FIRST HALF OF THE NEW WORK WEEK.
MARINE...
LIGHT SOUTHERLY WINDS (UNDER 15 KNOTS) THIS AFTERNOON OVER THE
CENTRAL GREAT LAKES WILL CONTINUE INTO TOMORROW AHEAD OF A COLD
FRONT. CONTINUED LOW LEVEL WARMING INTO SATURDAY AHEAD OF A COLD
FRONT SHOULD CAP WIND SPEEDS IN THE 15 TO 20 KNOT RANGE. NUMEROUS
SHOWERS AND THUNDERSTORMS DEVELOPING BY SATURDAY EVENING AS THE COLD
FRONT ENTERS THE REGION. THE FRONT IS EXPECTED TO DROP SOUTH OF THE
STATE SUNDAY MORNING, SUPPORTING JUST A CHANCE OF SHOWERS AND
THUNDERSTORMS OVER SOUTHERN LOWER MICHIGAN. ALTHOUGH THE FRONT
QUICKLY DROPS SOUTH OF THE STATE SUNDAY MORNING, STILL A LINGERING
CHANCE OF SHOWERS AND THUNDERSTORMS FOR GOOD PORTION OF THE DAY.
STRONG HIGH PRESSURE BUILDING OVER NORTHWEST ONTARIO AND SOLD COLD
ADVECTION (850 MB TEMPS LOWERING INTO LOWER TEENS/AROUND 10 C) OVER
LAKE HURON ON SUNDAY WILL ALLOW NORTHEAST WINDS TO REACH 20-25
KNOTS, WITH STILL THE POTENTIAL FOR WINDS TO BRIEFLY GUST TO AROUND
30 KNOTS. EVEN IF WINDS COME UP A BIT SHORT, THE PROLONG NORTHEAST
WINDS WILL ALLOW WAVES TO BUILD IN EXCESS OF 4 FEET ACROSS THE
NEARSHORE WATERS OF LAKE HURON, AS EASTERLY WINDS PERSIST INTO EARLY
NEXT WEEK WITH ANOTHER STRONG HIGH PRESSURE SYSTEM DEVELOPING OVER
EASTERN CANADA.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....MANN
DISCUSSION...KDK
MARINE.......SF
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