484
FXUS63 KDTX 260703
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
303 AM EDT SUN JUL 26 2026
KEY MESSAGES
- A LITTLE WARMER AND MORE HUMID TODAY AND MONDAY.
- ISOLATED STRONG TO SEVERE THUNDERSTORMS TODAY, WITH A MORE
ORGANIZED SEVERE WEATHER THREAT ARRIVING LATE MONDAY. DAMAGING WINDS
ARE THE PRIMARY HAZARD BOTH DAYS.
DISCUSSION
PREVAILING NORTHWEST FLOW IN THE MID-UPPER LEVELS WILL PERSIST
ACROSS THE GREAT LAKES REGION FOR THE NEXT COUPLE DAYS GIVEN THE
POSITION OF THE LARGE MID LEVEL RIDGE EXTENDING ACROSS THE ROCKIES
AND HIGH PLAINS.
AN ONGOING GRADUAL INFLUX OF HIGH LOW LEVEL THETA E AIR WILL
CONTRIBUTE TO A WARMER AND MORE HUMID DAY TODAY. THIS IN TURN WILL
TRANSLATE TO BUILDING INSTABILITY DURING THE COURSE OF THE DAY, WITH
VARIOUS HI RES SOLUTIONS FORECASTING 0-1KM MLCAPE VALUES RANGING
FROM 1K TO 2K J/KG. THE NORTHWEST FLOW WILL ALSO CONTRIBUTE TO A
STRONGLY SHEARED ENVIRONMENT, WITH 0-6KM BULK SHEAR VALUES FORECAST
TO RANGE FROM 30 TO 50 KNOTS ACROSS SE MI. MODEL SOUNDINGS INDICATE
A MID LEVEL WARM LAYER RESULTING IN A RESPECTABLE DEGREE OF CAPPING,
WHICH WILL LIKELY LIMIT CONVECTIVE COVERAGE TODAY. SUBTLE LARGE
SCALE FORCING VIA LOW A AMPLITUDE MID LEVEL SHORT WAVE WILL OFFER A
POTENTIAL FOR SOME EROSION OF THE CAP TODAY, WARRANTING LOW CHANCE
POPS. TAKING INTO CONSIDERATION THE DEEP LAYER SHEAR AND GOOD
DOWNDRAFT CAPE, ANY THUNDERSTORM THAT INITIATES WILL BE CAPABLE OF
PRODUCING DAMAGING WIND GUSTS.
RECENT CAMS SOLUTIONS CONTINUE TO INDICATE THE POTENTIAL FOR SEVERAL
CLUSTERS OF THUNDERSTORMS ACROSS THE GREAT LAKES REGION TONIGHT
THROUGH MONDAY NIGHT. TRENDS WITHIN THE MODEL SOLUTION SPACE ARE
SUGGESTING THE HIGHER CONVECTIVE PROBABILITIES TONIGHT INTO THE
FIRST HALF OF THE DAY MONDAY RESIDING EITHER OVER WESTERN LOWER MI
OR WISCONSIN/ILLINOIS ALONG AN AXIS OF HIGH INSTABILITY. WITHIN THE
MODEL PROBABILITY SPACE, CONVECTIVE POTENTIAL ACROSS SE MI INCREASES
LATE MONDAY AFTERNOON INTO MONDAY NIGHT. A STRONGER MID LEVEL SHORT
WAVE AND ASSOCIATED SFC FRONT WILL PROVIDE THE DYNAMIC FORCING TO
TRIGGER MORE WIDESPREAD CONVECTION. A CONTINUED STRONGLY SHEARED
ENVIRONMENT WILL REMAIN SUPPORTIVE OF SEVERE CONVECTION, THE COVERAGE
AND INTENSITY OF WHICH WILL RELY ON AVAILABLE INSTABILITY. THE
UNCERTAINTY IN EARLY DAY CONVECTIVE TRENDS WILL PLAY HEAVILY INTO
LATE DAY AVAILABLE INSTABILITY. THE POTENTIAL AFTERNOON RECOVERY IN
TEMPS WITH SFC DEWPOINTS IN THE UPPER 60S/NEAR 70 SUGGEST DIURNAL
RECOVERY MAY BE SWIFT. FOR THIS REASON, SPC CONTINUES TO HAVE ALL OF
SE MI IN A SLIGHT RISK MONDAY. THE UNCERTAINTY IN THE EVOLUTION OF
EARLY DAY THUNDERSTORM CLUSTERS HAS PREVENTED AN OUTLOOK UPGRADE AT
THIS TIME.
AMPLIFICATION OF THE LONGER WAVELENGTH TROUGH ACROSS THE MID
ATLANTIC/NORTHEAST TOWARD MID WEEK WILL DRIVE SLIGHT COOLER AND
DRIER AIR ACROSS LOWER MI. INCREASING ANTICYCLONIC FLOW WILL ALSO
WARRANT AN OVERALL DRY FORECAST MID WEEK.
MARINE
LIGHT SOUTHWEST WINDS DRAW WARMER AIR AND GREATER INSTABILITY INTO
THE CENTRAL GREAT LAKES LEADING TO INCREASING THUNDERSTORM ACTIVITY
TODAY, INCLUDING THE CHANCE FOR STRONG TO SEVERE STORMS THIS EVENING
AND TONIGHT. THE PRIMARY LOW PRESSURE SYSTEM THEN TRACKS ACROSS THE
NORTHERN GREAT LAKES DURING MONDAY. THUNDERSTORM ACTIVITY CONTINUES
TO INCREASE COVERAGE AND INTENSITY WITH THIS SYSTEM, ESPECIALLY
ALONG THE TRAILING COLD FRONT THAT BRINGS A CHANCE OF STRONG TO
SEVERE THUNDERSTORMS AS IT MOVES THROUGH THE REGION. OUTSIDE OF
STORMS, WIND AND WAVES ARE LOW UNTIL THE NORTHERLY WIND SHIFT POST
FRONT LATE MONDAY NIGHT INTO TUESDAY WHEN SPEEDS LIKELY REACH 25 TO
30 KNOTS OVER SOUTHERN LAKE HURON. IF THE LOW DEEPENS ENOUGH OVER
THE EASTERN GREAT LAKES TUESDAY EVENING, A SHORT PERIOD OF GALES
COULD EVEN COME INTO PLAY. WINDS SLOWLY DIMINISH ON WEDNESDAY AS
LARGE AREA OF HIGH PRESSURE OVER THE WESTERN GREAT LAKES SLOWLY
ADVANCES EAST, ARRIVING ON THURSDAY. THIS WILL ASSURE DRY CONDITIONS
FOR THOSE DAYS.
HYDROLOGY
CONVECTIVE RAINFALL CHANCES WILL INCREASE MONDAY AFTERNOON AND WILL
PEAK MONDAY EVENING. LOCALLY INTENSE RAINFALL RATES WILL BE POSSIBLE
WITH ANY CONVECTION. THERE IS THE POTENTIAL FOR A COUPLE ROUNDS OF
SHOWERS/THUNDERSTORMS OVER SOME AREAS DURING THIS TIME PERIOD.
PROBABILITIES FOR A QUARTER TO ONE INCH OF RAIN ARE MODERATE TO
HIGH. THE CHANCES FOR LOCATIONS TO EXCEED AN INCH ARE LOW (LESS THAN
20 PERCENT) AT THIS TIME.
PREV DISCUSSION
ISSUED AT 1153 PM EDT SAT JUL 25 2026
AVIATION...
VFR CEILING OF 4-6 KFT OVER MOST OF LOWER MI IS THE RESULT OF
MOISTURE SLOWLY INCREASING WITHIN THE DIFFUSE PATTERN BETWEEN
ATLANTIC COAST HIGH PRESSURE AND LOW PRESSURE SLOWLY ORGANIZING FROM
THE CENTRAL PLAINS INTO CENTRAL CANADA. THE CLOUDS ARE AHEAD OF THE
SURFACE WARM FRONT WAVERING NORTH-SOUTH ALONG THE MS RIVER VALLEY.
THIS FRONT IS NOT PROJECTED TO MOVE MUCH TOWARD LOWER MI LATE
TONIGHT LEAVING THE EXPECTATION FOR LOW VFR CEILING TO PERSIST WITH
A FEW PATCHES OF MVFR REACHING THE SE MI TERMINAL CORRIDOR FROM THE
PRIMARY AREA THAT EXTENDS FROM THE UPPER MIDWEST INTO THE LOWER OHIO
VALLEY.
SHOWER AND THUNDERSTORM TRENDS ARE ALSO BEING MONITORED AS THE
WEATHER FOCUS FOR LATE TONIGHT AND SUNDAY. PREDICTABILITY REMAINS
LOW, HOWEVER RECENT HI-RES MODEL DATA SUGGESTS ISOLATED SHOWERS
DEVELOP WITHIN THE NOCTURNAL CLOUD FIELD LATE TONIGHT TO EARLY
MORNING, MAINLY TOWARD NORTHERN AND WESTERN LOWER MI. THAT IS
FOLLOWED BY SCATTERED THUNDERSTORM POTENTIAL JUST ABOUT ANYWHERE IN
SE MI WITHIN AN UNCAPPED PROFILE AND AS DAYTIME HEATING BUILDS FROM
LATE MORNING THROUGH THE AFTERNOON. A PROB30 IS INTRODUCED IN THIS
FORECAST ISSUANCE FOR THE USUAL MID/LATE AFTERNOON HOURS OF PEAK
INSTABILITY WITH FURTHER COVERAGE AND TIMING REFINEMENT LIKELY IN
LATER UPDATES.
D21/DTW CONVECTION... THERE IS A LOW CHANCE OF THUNDERSTORMS SUNDAY
AFTERNOON AND EVENING. CONFIDENCE IN COVERAGE AND TIMING REMAIN LOW.
DTW THRESHOLD PROBABILITIES...
* MODERATE FOR CEILING 5000 FT OR LESS LATE TONIGHT THROUGH SUNDAY.
* LOW FOR THUNDER SUNDAY AFTERNOON AND EVENING.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
DISCUSSION...SC
MARINE.......SF
HYDROLOGY....SC
AVIATION.....BT
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