250
FXUS63 KDTX 201803
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
203 PM EDT SAT JUN 20 2026
KEY MESSAGES
- SCATTERED SHOWERS AND A RUMBLE OF THUNDER WILL BE POSSIBLE NORTH
OF I 69 THIS AFTERNOON AND INTO THE EARLY EVENING.
- DRY FOR MUCH OF SUNDAY. BROADER COVERAGE OF SHOWERS AND
THUNDERSTORMS WILL DEVELOP SUNDAY NIGHT, ESPECIALLY SOUTH OF I-94.
HEAVY RAINFALL IS POSSIBLE IF THE LOW PRESSURE SYSTEM TRACKS FARTHER
NORTH.
- 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.
DISCUSSION
ZONAL TO PSEUDO NORTHWEST FLOW WILL REMAIN IN PLACE OVER SOUTHEAST
MICHIGAN THROUGHOUT MUCH OF THE NEXT 7 DAYS LEADING TO SLIGHTLY
BELOW NORMAL TEMPERATURES ACROSS THE REGION. A MODEST SOUTHERN
STREAM JET IMPULSE IS FORECASTED TO EJECT ACROSS THE PLAINS LATE
THIS WEEKEND PHASING WITH AND ENTRANCE REGION TO THE UPPER LEVEL JET
AXIS OVER THE UPPER MIDWEST AND GREAT LAKES.
FORECAST THOUGHTS FOR THIS AFTERNOON AND EARLY EVENING WERE PROVIDED
IN PRIOR DISCUSSIONS INCLUDING THE UPDATE. SHOWER AND THUNDERSTORM
CHANCES OVER THE NORTHERN FORECAST AREA WILL BRING THE POTENTIAL FOR
A HEAVY DOWNPOUR AND POSSIBLY SOME SMALL HAIL.
WEAK UPPER LEVEL JETLET AND POTENTIAL VORTICITY ANOMALY IS
FORECASTED TO INDUCE LEESIDE CYCLOGENESIS TONIGHT INVOF COLORADO.
STRONG MODEL CONSENSUS THEN EXISTS THAT A HYBRID BAROCLINIC/MCV LOW
PRESSURE SYSTEM WILL THEN EJECT EASTWARD THROUGH THE MID MISSISSIPPI
RIVER VALLEY LATE SUNDAY AFTERNOON AND EVENING. SOME SIGNIFICANT
DETAILS REMAIN UNCERTAIN AT THIS VANTAGE POINT, INCLUDING WHETHER OR
NOT THE MCV WILL REMAIN ATTACHED TO ANY DEEPER 850-700MB THETAE
AXES. IT REMAINS LIKELY THAT DEEP COLUMN, BOUNDARY LAYER ROOTED
CONVECTION WILL FAVOR A TRACK THROUGH CENTRAL TO SOUTHERN ILLINOIS
AND SOUTHERN INDIANA BASED ON HREF ENSEMBLE MEAN OF CAPE. GREAT
SUPPORT FOR LARGE SCALE ASCENT IS EXPECTED TO ARRIVE HERE LOCALLY,
GIVEN THE PHASING OF THE NORTHERN STREAM AND THE
CONFIGURATION/ORGANIZATION TO THE RIGHT ENTRANCE REGION DYNAMICS.
DETAILS WILL NEEDED TO BE SORTED WITH NOTABLE AND MEANINGFUL NORTH
TO SOUTH DIFFERENCES OF MOST FAVORABLE 700MB AND 850MB
FRONTOGENESIS. THE NAM AND NAM NEST SOLUTIONS ARE SOMETHING TO
MONITOR GIVEN THE AMOUNT OF QPF IN THE SOLUTIONS (EXCEEDING 1 INCH)
FOR PORTIONS OF FAR SOUTHEAST MICHIGAN. ADDITIONALLY, THE EPS
DATASET IS VERY SUPPORTIVE OF QPF AMOUNTS FOR SOUTHEAST MICHIGAN
WITH THE MEAN AT DTW AT OVER 1.00 INCH AND WITH THE 90TH PERCENTILE
AT/ABOVE 2.50 INCHES. THE CURRENT FORECAST HAS
CATEGORICAL/WIDESPREAD RAIN CHANCES FOR AREAS SOUTH OF THE I 69
CORRIDOR SUNDAY NIGHT. WILL FORGO ANY FLOOD WATCH THIS FORECAST
PACKAGE AND WILL ALLOW FOR MORE MODEL DATA. NO SEVERE WEATHER IS
ANTICIPATED WITH THE SUNDAY NIGHT SYSTEM HERE IN SOUTHEAST MICHIGAN.
HIGH CONFIDENCE EXISTS THAT SHOWER AND RAIN CHANCES WILL END BY
MIDDAY MONDAY. SUBSIDENCE AND STEEP DOWNWARD VERTICAL MOTION IS
FORECASTED AFTER 18Z WHICH SHOULD LEAD TO A QUICK CLEARING TREND.
NORTHEAST GRADIENT WIND IS FORECASTED WHICH COULD HOLD ON A TOUCH
INTO THE EVENING BEFORE LAYING DOWN. HIGHS MONDAY ONLY TOPPING OUT
IN THE LOWER 70S, WITH TEMPERATURES LOWERING INTO THE LOWER 60S BY
MIDNIGHT.
STRONG CANADIAN RIDGE OF HIGH PRESSURE IS EXPECTED TO BUILD ACROSS
THE STATE TUESDAY AND EARLY WEDNESDAY. DEEP PV RESERVOIR AND
TROUGHING IS SHOWN TO PUSH EASTWARD BY WEDNESDAY REESTABLISHIGN
TROUGHING OVER THE GREAT LAKES FOR THE END OF THE WEEK. IT JUST
LOOKS LIKE A CONTINUATION OF BELOW NORMAL TEMPERATURES AT THE END OF
THE PERIOD.
MARINE
A DIFFUSE AREA OF HIGH PRESSURE WILL LINGER OVER THE GREAT LAKES
THROUGH SUNDAY, SUPPORTING A CONTINUATION OF LIGHTER WINDS. PERIODIC
RAIN SHOWERS WILL BE POSSIBLE TODAY AS AN UPPER-LEVEL DISTURBANCE
SLOWLY MOVES ACROSS THE REGION. A COMPACT LOW PRESSURE SYSTEM WILL
THROUGH THE OHIO VALLEY AND SOUTHERN GREAT LAKES REGION TOMORROW
NIGHT. RAIN SHOWERS ARE EXPECTED TO BE CONCENTRATED ACROSS LAKE ERIE
UP TO LAKE ST. CLAIR. ELEVATED NORTHEASTERLY WINDS WILL INCREASE
TOMORROW NIGHT AND PERSIST THROUGH THE DAYLIGHT HOURS ON MONDAY. THE
LONGER ONSHORE FETCH ON LAKE ERIE WILL SUPPORT HIGHER WAVES BY
DAYBREAK MONDAY.
HYDROLOGY
UNSEASONABLY STRONG LOW PRESSURE SYSTEM IS FORECASTED TO EJECT
EASTWARD THROUGH THE MID MISSISSIPPI RIVER VALLEY LATE SUNDAY AND
THROUGH PORTIONS OF THE OHIO RIVER VALLEY SUNDAY NIGHT. WIDESPREAD
SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED TO DEVELOP ALONG THE
NORTHERN PERIPHERY OF THE LOW PRESSURE SYSTEM AND MAY BRING HEAVY
RAINFALL. WHILE UNCERTAINTY EXISTS TO THE EXACT TRACK OF THE HEAVY
RAINFALL, THE POTENTIAL EXISTS FOR RAINFALL AMOUNTS TO EXCEED 1 INCH
ACROSS SOME PORTION OF SOUTHERN SOUTHEAST MICHIGAN. THE CURRENT
MODEL CONSENSUS AND FORECAST SUPPORTS HIGHER RAINFALL AMOUNTS SOUTH
OF DETROIT ALONG THE OHIO BORDER. HEAVY RAINFALL AND HIGHER AMOUNTS
WILL BE POSSIBLE IF THE LOW PRESSURE SYSTEM TRACKS NORTHWARD. IF
HEAVY RAINFALL AXIS TRENDS FARTHER NORTH, SOME POTENTIAL FOR URBAN
FLOODING WILL EXIST.
PREV DISCUSSION
ISSUED AT 122 PM EDT SAT JUN 20 2026
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.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
DISCUSSION...CB
MARINE.......GEM
HYDROLOGY....CB
AVIATION.....RBP
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AT WWW.WEATHER.GOV/DETROIT.
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