116
FXUS63 KDTX 201722
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
122 PM EDT SAT JUN 20 2026
KEY MESSAGES
- SCATTERED SHOWERS AND A RUMBLE OF THUNDER THIS MORNING CONTINUE
THIS AFTERNOON WHILE SHIFTING WITH GREATER COVERAGE TOWARD THE TRI
CITIES AND THUMB. THERE IS A BETTER CHANCE FOR AN ORDINARY
THUNDERSTORM THIS AFTERNOON NORTH OF I-69.
- DRY TONIGHT AND SUNDAY.
- BROADER COVERAGE OF SHOWERS AND THUNDERSTORMS DEVELOP SUNDAY
NIGHT, ESPECIALLY SOUTH OF I-94.
- SHOWERS LINGER MONDAY MORNING THEN DRY IN THE AFTERNOON AND
EVENING.
- COOLER THAN NORMAL TEMPERATURES ARE EXPECTED THROUGH AT LEAST THE
MIDDLE OF NEXT WEEK.
AVIATION
WEAK SURFACE LOW WILL CONTINUE TO MOVE THROUGH LOWER MI THIS
AFTERNOON AND EARLY EVENING. THIS IN COMBINATION WITH MODEST
INSTABILITY WILL KEEP WIDESPREAD CUMULUS DEVELOPING INTO SHOWERS
NORTH OF THE DETROIT TAF SITES. THERE IS ENOUGH INSTABILITY THAT THE
STRONGEST SHOWERS COULD PRODUCE THUNDER, BUT SHOULD BE ISOLATED
ENOUGH TO LEAVE OUT OF THE PTK, FNT AND MBS TAFS. FOR THOSE DETROIT
TAFS, JUST EXPECT THE CUMULUS TO BECOME BROKEN THIS AFTERNOON.
OTHERWISE, A GUSTY WEST WIND OF 10-15 KNOTS WILL CONTINUE THROUGH
THE AFTERNOON AND EARLY EVENING.
WITH THE SURFACE LOW MOVING FARTHER EAST AND THE LOSS OF DIURNAL
HEATING, EXPECT THE SHOWERS TO DISSIPATE QUICKLY JUST AFTER 00Z AND
THE CUMULUS TO FOLLOW BETWEEN 00Z AND 04Z. UPPER MIDWEST HIGH
PRESSURE BUILDS INTO LOWER MI LATE TONIGHT BRINGING MOSTLY CLEAR
SKIES AND LIGHT NORTHWEST WIND. WILL DELAY FOG POTENTIAL UNTIL A
SHALLOW MVFR RESTRICTION DEVELOPS CLOSER TO SUNRISE, MAINLY IN THE
FNT TO MBS AREA WHERE WET GROUND CAN AUGMENT SURFACE BASED MOISTURE.
THE FIRST HALF OF SUNDAY WILL FEATURE FEW-SCT DIURNAL CUMULUS
DEVELOPMENT AS A THICKENING CIRRUS DECK MOVES IN AHEAD OF THE NEXT
SYSTEM FOR MAINLY SUNDAY NIGHT.
D21/DTW CONVECTION... THUNDERSTORM POTENTIAL HOLDS NORTH OF DTW
TOWARD THE NORTHERN FRINGE OF D21 FOR THE REMAINDER OF THIS
AFTERNOON AND EVENING.
DTW THRESHOLD PROBABILITIES
* LOW FOR CEILING AT OR BELOW 5000 FT THIS AFTERNOON AND EVENING.
PREV DISCUSSION
ISSUED AT 1016 AM EDT SAT JUN 20 2026
UPDATE...
LOW-MIDLEVEL FRONTOGENESIS ASSOCIATED WITH DEEPER GEOPOTENTIAL
INFLECTION/TROUGHING BROUGHT AN ELONGATED CORRIDOR OF SHOWER
ACTIVITY TO THE SAGINAW BAY REGION AND NORTHERN THUMB THIS MORNING.
MODEL DATA SUPPORTS AN AXIS OF SHEARED 500MB ABSOLUTE VORTICITY
TAKING ITS TIME TO WORK ACROSS THE NORTHERN CWA TODAY. THERMAL PROGS
SUGGEST A DIFFERENTIAL HEATING BOUNDARY (WITH CLOUD TO THE NORTH)
WILL DEVELOP OVER THE SOUTHERN PORTIONS OF THE THUMB EFFECTIVELY
LINING OUT WITH THE MEAN FLOW. SOLUTIONS SUPPORT A SURFACE LOW
REFLECTION EMERGING THIS AFTERNOON PROVIDING A FOCUS FOR CONVECTIVE
DEVELOPMENT OR LIFTING MECHANISM. ENHANCED LOW LEVEL THETAE IS
EXPECTED TO POOL ALONG THE BOUNDARY RESULTING IN MODEST MIXED LAYER
CAPE OF APPROXIMATELY 500-750 J/KG. THE BOTTOM LINE IS COULD SEE
SOME SHOWER ACTIVITY WANE LATE THIS MORNING BEFORE SHOWERS AND
ISOLATED THUNDERSTORMS RE-INITIATE THIS AFTERNOON DURING PEAK
HEATING. BULK OF HIRES SOLUTIONS SUGGESTS AFTER 19Z, PRECIPITATION
POTENTIAL LASTING AS LATE AS 2Z. INTERESTING TO SEE 0-6KM BULK SHEAR
VALUES UP TO 30 KNOTS WHICH COULD ALLOW FOR ENOUGH STORM
ORGANIZATION OF DISCRETE OR MULTICELLS TO OBSERVE SOME HAIL OF LESS
THAN 1 INCH.
PREV DISCUSSION...
ISSUED AT 352 AM EDT SAT JUN 20 2026
DISCUSSION...
MODEST SURFACE LOW PRESSURE TRAVERSING LOWER MI HAS POCKETS OF
SHOWERS ONGOING DURING THE LATE NIGHT. THE SURFACE SYSTEM IS TIED TO
A COMPACT MID/UPPER LEVEL SHORT WAVE PRODUCING SOME ELEVATED
MOISTURE TRANSPORT TO FUEL THE OBSERVED SHOWER PATTERN WHICH
CONTAINS A STRAY RUMBLE OF THUNDER. THIS WAVE QUICKLY SHEARS
EASTWARD DURING THE MORNING AND LEAVES BEHIND LARGER SCALE MID/UPPER
LEVEL DEFORMATION OVER LOWER MI THAT IS CONNECTED TO A LARGER CLOSED
LOW IN CENTRAL CANADA. THE RESULTING NEUTRAL TO SLIGHTLY UPWARD
VERTICAL MOTION IN THIS ZONE ALLOWS THE LINGERING SURFACE LOW/TROUGH
TO BE THE FOCUS OF NEW SHOWER/STORM DEVELOPMENT DURING PEAK
AFTERNOON HEATING, MAINLY TOWARD THE TRI CITIES AND THUMB. THE NEW
00Z HREF AND MODEL SOUNDINGS ADVERTISE LOW DENSITY SURFACE BASED
CAPE HOVERING AROUND 500 J/KG BY MID AFTERNOON, JUST ENOUGH FOR AN
ISOLATED ORDINARY THUNDERSTORM UNTIL ACTIVITY FADES WITH SUNSET.
A SUBTLE SHORT WAVE RIDGE AND DIFFUSE SURFACE HIGH PRESSURE
MAINTAINS DRY WEATHER FOR THE REST OF TONIGHT AND THROUGH SUNDAY.
CONSENSUS OF 00Z DETERMINISTIC MODELS THEN KEEPS THE CURRENT CENTRAL
ROCKIES SYSTEM ON TIME TO REACH THE OHIO VALLEY SUNDAY NIGHT. THE
MID/UPPER LEVEL WAVE INITIATES TEXTBOOK LEE SIDE SURFACE
CYCLOGENESIS DURING THE DAY WHICH SWEEPS UP READILY ACCESSIBLE GULF
MOISTURE TO FUEL CONVECTION. CENTRAL PLAINS MCS DEVELOPMENT IS
LIKELY AS A RESULT WHICH PROPAGATES INTO THE MID MS/LOWER OH VALLEY
DURING SUNDAY. THE RESULTING HYBRID SHORT WAVE/MCV KEEPS THE OH
VALLEY SURFACE TO LOW LEVEL FRONTAL ZONE ACTIVE SUNDAY NIGHT WHILE
AN ELEVATED PATTERN OF MOISTURE TRANSPORT GRAZES LOWER MI. THE
FORECAST QUESTION OVER THE LAST FEW CYCLES HAS BEEN HOW FAR NORTH
SHOWERS/STORMS WILL BE ABLE TO REACH INTO LOWER MI WHILE THE SYSTEM
SHEARS QUICKLY EASTWARD DURING THE NIGHT AND EARLY MONDAY. THE LOW
LEVEL JET IS DIRECTED MORE TOWARD THE OH/TN VALLEYS KEEPING THE 850-
700 MB FLOW WEAKER AND QUICK TO FLIP NW OVER THE GREAT LAKES LATER
SUNDAY NIGHT. THESE LARGER SCALE TRENDS CONTINUE TO FAVOR A SHARP
RAINFALL GRADIENT WITH LIMITED NORTHWARD EXTENT. DETERMINISTIC
REGIONAL MODEL CONSENSUS OF 1 INCH EVENT TOTALS ARE NOW NEAR OR JUST
SOUTH OF THE OHIO BORDER DECREASING TO JUST TRACE AMOUNTS TOWARD THE
I-69 CORRIDOR. THIS IS LIKELY TO BE REFLECTED IN NBM RUNS OVER THE
NEXT FEW MODEL CYCLES.
DRY WEATHER HOLDS MONDAY AFTERNOON AND NIGHT AS SLIGHTLY COOLER
NORTH WIND DEVELOPS OVER LOWER MI ON THE HEELS OF THE OHIO VALLEY
SYSTEM. SURFACE HIGH PRESSURE INFLUENCE THEN LASTS THROUGH TUESDAY
FOLLOWED QUICKLY BY THE NEXT MIDWEST LOW PRESSURE SYSTEM FOR
WEDNESDAY.
MARINE...
A RIDGE OF HIGH PRESSURE WILL BUILD IN THIS MORNING WHICH WILL
SUPPORT LIGHT WINDS THROUGH THE DAY. A DIFFUSE AREA OF HIGH PRESSURE
WILL THEN REMAIN OVER THE GREAT LAKES THROUGH THIS WEEKEND AND WILL
MAINTAIN THE LIGHTER WINDS. PERIODIC RAIN SHOWERS WILL BE POSSIBLE
TODAY AS AN UPPER-LEVEL DISTURBANCE HOLDS OVER THE REGION. A LOW
PRESSURE SYSTEM WILL THEN ARRIVE OVER THE OHIO VALLEY AND SOUTHERN
GREAT LAKES TOMORROW NIGHT. THIS WILL BRING THE NEXT LIKELY CHANCES
FOR RAIN, EMBEDDED THUNDERSTORMS AND ELEVATED WINDS CENTERED LATE
TOMORROW THROUGH MONDAY MORNING. MOST OF THIS ACTIVITY IS EXPECTED
TO BE CONCENTRATED ACROSS LAKE ERIE UP TO LAKE ST. CLAIR.
HYDROLOGY...
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS PRODUCE GENERALLY LESS
THAN 0.25 INCH OF RAINFALL TODAY. DRY WEATHER TONIGHT AND SUNDAY
LEADS INTO A MORE WIDESPREAD SHOWER AND THUNDERSTORM PATTERN THAT
INCREASES SUNDAY EVENING AND CONTINUES INTO MONDAY MORNING, MAINLY
SOUTH OF I-69. STRONGER LOW PRESSURE TRACKING THROUGH THE OHIO
VALLEY PULLS GULF MOISTURE NORTHWARD INTO SOUTHERN LOWER MI RESULTING
IN PERIODS OF HEAVIER SHOWERS AND THUNDERSTORMS. RAINFALL TOTALS
FROM SUNSET SUNDAY EVENING UNTIL NOON MONDAY HAVE A CHANCE TO REACH
AROUND 1 INCH, MAINLY FROM THE OHIO BORDER NORTHWARD BUT HOLDING
SOUTH OF THE I-94 CORRIDOR. TOTALS DROP OFF QUICKLY ACROSS METRO
DETROIT TO LESS THAN 0.25 INCH TOWARD THE M-59 CORRIDOR. THIS
SCENARIO PRESENTS A LOW THREAT OF FLOODING LIMITED TO MINOR PONDING
OF WATER ON ROADS AND IN OTHER PRONE AREAS UNTIL THE RAIN ENDS BY
MONDAY AFTERNOON.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....RBP
UPDATE.......CB
DISCUSSION...BT
MARINE.......AM
HYDROLOGY....BT
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