291
FXUS63 KDTX 122259
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
659 PM EDT WED AUG 12 2026
KEY MESSAGES
- SCATTERED THUNDERSTORMS DEVELOP OVERHEAD THIS AFTERNOON AND
EVENING. ISOLATED SEVERE STORMS WILL BE POSSIBLE.
- MAINLY DRY CONDITIONS DEVELOP THURSDAY THROUGH MOST OF SATURDAY.
- RENEWED CHANCES FOR SHOWERS AND THUNDERSTORMS LATE SATURDAY INTO
SUNDAY.
AVIATION
A COMPOSITE OUTFLOW/BACKDOOR FRONT IN THE NEAR SURFACE ENVIRONMENT
WITH DEFORMATION IN THE MIDLEVELS HAS CREATED AN AXIS OF FAVORED
ASCENT AND THUNDERSTORM DEVELOPMENT MAINLY NORTH OF I 69. NWP HIRES
SIGNAL SUGGESTS THIS CONVERGENCE AXIS WILL LEAD TO ADDITIONAL
SHOWERS AND THUNDERSTORMS THROUGH APPROXIMATELY 2Z BETWEEN THE M46
AND I 69 CORRIDORS. THERE IS LESS CONFIDENCE THAT SHOWERS AND
THUNDERSTORMS WILL BE ABLE TO PERSIST INTO NORTHERN PORTIONS OF METRO
DETROIT THIS EVENING. LACK OF FLOW WITH HIGH SURFACE BASED HUMIDITY
AND EVAPOTRANSPIRATION BRINGS THE POTENTIAL FOR FOG DEVELOPMENT
AGAIN LATE TONIGHT AND DAYBREAK. LOW CONFIDENCE IN ANY IFR OR LIFR
CONDITIONS.
D21/DTW CONVECTION...THERE IS LOW CONFIDENCE THAT SHOWERS AND
THUNDERSTORMS WILL PUSH SOUTHWARD INTO DTW AIRSPACE THIS EVENING.
DTW THRESHOLD PROBABILITIES
* HIGH FOR CEILING 5000 FEET OR LESS TONIGHT AND THURSDAY.
* LOW FOR THUNDERSTORMS THIS EVENING.
PREV DISCUSSION
ISSUED AT 350 PM EDT WED AUG 12 2026
DISCUSSION...
THE GREAT LAKES AND OHIO VALLEY REMAINED LOCKED INTO AN UNSETTLED
DEFORMATION PATTERN AGAIN TODAY, WHICH STEERED YET ANOTHER MCS
ACROSS THE OHIO VALLEY. A LACKLUSTER SHOWING LOCALLY WITH JUST A
BRIEF FLARE UP IN SHOWER ACTIVITY NEAR THE STATE LINE ALREADY
DECAYING AT ISSUANCE. THAT SAID, COMPOSITE REFLECTIVITY DOES SHOW
OUTFLOW EMANATING NORTH FROM THE COMPLEX WHICH WILL BE ONE OF
SEVERAL SMALL-SCALE FORCING MECHANISMS CAPABLE OF TRIGGERING
ADDITIONAL CONVECTION THIS EVENING.
STABLE BUT MOIST LOW LEVELS CHARACTERIZE THE AIRMASS ACROSS THE
SOUTHERN COUNTIES WHERE SURFACE DEWPOINTS ARE NEAR 70 DEGREES.
DELINEATION IN CLOUD COVER THROUGHOUT THE DAY HAS SET UP AN
IMPRESSIVE DIFFERENTIAL HEATING BOUNDARY AROUND THE I-94 CORRIDOR.
TEMPERATURES UNDERNEATH THE STRATUS DECK ARE ONLY IN THE LOW 70S
COMPARED TO LOW 80S IN PARTIAL SUN TO THE NORTH. WITH 6.0-6.5 C/KM
MID LEVEL LAPSE RATES PRESENT ACROSS ALL OF SE MICHIGAN, INSTABILITY
IS TIED TO THE MOISTENED BOUNDARY LAYER CONDITIONS WHICH ARE MOST
FAVORABLE WHERE RAIN FELL EARLIER TODAY ACROSS THE SAGINAW
VALLEY/THUMB REGION AND NEAR THE LAKE HURON SHORELINE. THIS ALSO
HAPPENS TO BE WHERE THE NOSE OF AN UPPER LEVEL JET WILL CONNECT WITH
LOW LEVEL TROUGHING TO PRESENT A MORE FOCUSED AREA OF WEAK ASCENT
THIS EVENING.
CURRENT SATELLITE TRENDS SHOW A FEW SPOTS WHERE TOWERING CUMULUS IS
ATTEMPTING TO GAIN TRACTION, MAINLY ALONG THE LAKE BREEZE INFLUENCE
FROM BAD AXE SOUTH. THE EXISTING STABLE LAYER IS STILL BROADLY
PREVENTING DEEP CONVECTIVE GROWTH, AS HAS BEEN THE CASE THE PAST
SEVERAL DAYS, ALTHOUGH A COUPLE OF DEEPER CORES HAVE DEVELOPED ALONG
THE INTERACTING LAKE BREEZE BOUNDARIES. EXPECTATION IS FOR THE
ARRIVAL OF THE SYNOPTIC ASCENT AND LAKE BREEZES/OUTFLOW TO PIECE
TOGETHER ENOUGH ASCENT FOR MORE UPDRAFTS TO BREAK THROUGH THE CAP.
THUS ADDITIONAL CONVECTION DEVELOPMENT IS EXPECTED OVERHEAD THROUGH
THE EVENING (ROUGHLY 22Z-03Z OR 6PM-11PM EDT). THIS WILL MAINLY
OCCUR NORTH OF THE M-59 CORRIDOR WHERE INSTABILITY IS MOST
FAVORABLE. THE DEEPEST UPDRAFTS WILL HAVE ACCESS TO ~40 KNOTS OF 0-
6KM BULK SHEAR AND CAPE DENSITY THROUGHOUT THE MID-LEVELS. ISOLATED
STORMS WILL THUS BE CAPABLE OR 1+ INCH HAIL AND DOWNBURSTS OF 60+
MPH. SWODY1 CONTINUES TO HIGHLIGHT A MARGINAL RISK FOR MUCH OF THE
AREA.
LOW CONFIDENCE PATTERN LINGERS THROUGH THE REST OF THE WEEK INTO THE
WEEKEND AS THE DEFORMATION AXIS LOITERS OVER THE OHIO VALLEY.
DISJOINTED MOISTURE AND WEAK FORCING WILL CONTINUE TO STRUGGLE
GENERATING CONVECTION, WHILE A SOUTHWARD SHIFT IN THE BOUNDARY
THURSDAY FAVORS A DRY FORECAST FOR ALL OF SE MICHIGAN. THIS BOUNDARY
DOES ATTEMPT TO LIFT BACK NORTH FRIDAY-THIS WEEKEND, BUT WILL BE
COMPETING WITH HIGH PRESSURE OVER ONTARIO WHICH KEEPS BETTER
MOISTURE/INSTABILITY TO OUR SOUTH AND WEST. UPSTREAM CONVECTION MAY
STILL HAVE AN IMPACT ON CLOUD COVER, WHILE RESIDUAL LOW LEVEL
MOISTURE AFFORDS FOG CHANCES AGAIN THURSDAY MORNING--BOTH
INFLUENCING TEMPERATURES.
RELIEF FROM THIS UNSETTLED PATTERN FINALLY ARRIVES LATE THIS WEEKEND-
EARLY NEXT WEEK AS LOW PRESSURE EJECTS OUT OF THE NORTHERN ROCKIES
INTO CANADA. THIS DRIVES A COLD FRONT ACROSS THE UPPER MIDWEST AND
GREAT LAKES WHICH BRINGS AN INCREASED CHANCE OF SHOWERS AND STORMS
THIS WEEKEND, BUT A BOUT OF HIGH PRESSURE BEHIND IT. SEASONABLE
TEMPERATURES IN THE LOW-MID 80S ARE EXPECTED THROUGHOUT THE 7-DAY
FORECAST PERIOD.
MARINE...
A STALLED FRONT NEAR THE SOUTHERN MICHIGAN BORDER WILL CONTINUE TO
BE A FOCUS FOR MULTIPLE ROUNDS OF THUNDERSTORMS OVER THE NEXT COUPLE
DAYS. LAKE ST CLAIR AND LAKE ERIE HAVE THE HIGHEST CHANCES OF
CONVECTION AFFECTING THEM BEING CLOSER TO THE STALLED FRONT, BUT
PERIODIC CHANCES WILL CONTINUE FURTHER NORTH AS WELL. OUTSIDE OF ANY
CONVECTION, HIGH PRESSURE TO THE NORTH OF THE FRONT WILL PROVIDE
GENERALLY LIGHT NORTHWESTERLY WINDS THROUGH THURSDAY AT 10 KNOTS OR
LESS. WITH THE LIGHTER WINDS, THERE ARE SOME WEAK SIGNALS FOR PATCHY
DENSE FOG OVER LAKE HURON AT TIMES, THROUGH CONFIDENCE REMAINS LOW.
ON FRIDAY, THE HIGH PUSHES EASTWARD ACROSS THE CENTRAL AND EASTERN
GREAT LAKES WHICH WILL FAVOR AN UPTICK IN NORTHEAST WINDS. WINDS
THEN TURN SOUTHERLY LATE SATURDAY AND INCREASE TO AROUND 20 KNOTS
AHEAD OF A COLD FRONT SATURDAY NIGHT.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....CB
DISCUSSION...MV
MARINE.......DRK
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