276
FXUS63 KDTX 200925
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
525 AM EDT MON APR 20 2026
KEY MESSAGES
- A FREEZE WARNING REMAINS IN EFFECT THIS MORNING FOR MOST OF
SOUTHEAST MICHIGAN AS LOWS DROP INTO THE MID 20S.
- VERY DRY CONDITIONS ARE EXPECTED THIS AFTERNOON WITH RELATIVE
HUMIDITY VALUES DROPPING TO AROUND 30 PERCENT.
- TEMPERATURES WARM BACK TOWARD NORMAL TUESDAY, CLIMBING WELL ABOVE
NORMAL THROUGH THE REST OF THE WORKWEEK.
- WIDESPREAD RAIN CHANCES INCREASE AGAIN BY FRIDAY.
AVIATION
LIGHT NORTHWEST WINDS THIS MORNING WILL BACK TO THE SOUTH THIS
EVENING AS A HIGH PRESSURE CENTER DRIFTS ACROSS LOWER MICHIGAN.
NEARLY SKC CONDITIONS EXPECTED THROUGH THIS EVENING, WITH SOME MID-
CLOUD (BASED AROUND 10 KFT) MOVING IN OVERNIGHT AS A WAVE TRACKS
THROUGH ONTARIO. SOUTHERLY WINDS THEN BEGIN TO INCREASE ABOVE 10
KNOTS TOWARD 12Z TUESDAY MORNING AS THE NEXT LOW AND ASSOCIATED
FRONTAL BOUNDARY APPROACH THE GREAT LAKES REGION.
DTW THRESHOLD PROBABILITIES
* NONE.
PREV DISCUSSION
ISSUED AT 238 AM EDT MON APR 20 2026
DISCUSSION...
THE CENTER OF LOW-MIDLEVEL HIGH PRESSURE WILL PUSH FROM NW WISCONSIN
THIS MORNING TO THE WESTERN BASIN OF LAKE ERIE BY THIS EVENING. FOR
TODAY, THE FORECAST AREA WILL BE LOCATED WITHIN THE EASTERN FLANK OF
THE HIGH PRESSURE IN A FAVORABLE ZONE FOR ANTICYCLONIC FLOW
TRAJECTORIES AND SYSTEM RELATIVE ISENTROPIC DOWNGLIDE. OUTSIDE OF
SOME ISOLATED LAKE EFFECT CLOUD IN VICINITY OF LAKE HURON, THE
FORECAST AREA WILL LARGELY EXPERIENCE LOW SKY FRACTION. 850MB
TEMPERATURES IN THE -9 TO -13C RANGE WILL LIMIT HIGHS IN THE 40S,
SOME 12 TO 15 DEGREES BELOW NORMAL. NOTABLE ITEM IS VERY LOW RH,
LIKELY FALLING INTO THE 20S TO LOW 30S PERCENT RANGE.
TROUGH AXIS GETS SHOVED EASTWARD TONIGHT ALLOWING FOR MODERATED
AIRMASS WITH RAPID SURFACE DEWPOINT RECOVERY (TDS OF UPPER 40S TO
NEAR 50) BY TUESDAY EVENING. INITIAL STAGE OF SYNOPTIC SCALE WARM
ADVECTION COULD SUPPORT POSSIBLE SPRINKLES IN THE 10-14Z TIME WINDOW
TUESDAY MORNING. ELEVATED ACTIVITY BUT THERE IS AT LEAST SOME
EVIDENCE THAT THE LOWER LEVELS WILL DRY TO SATURATE. SOUTHWEST WINDS
OF 15 TO 25 MPH ARE EXPECTED BY LATE MORNING AND EARLY AFTERNOON AS
THE LARGE WAVELENGTH UPPER LEVEL RIDGE EXPANDS EASTWARD ACROSS NORTH
AMERICA. A FEATURE TO KEY ON WILL BE A RELATIVELY NARROW HIGHER
THETAE PLUME THAT WILL ADVECT THROUGH PORTIONS OF NORTHERN INDIANA
AND ACROSS FAR SOUTHERN LOWER MICHIGAN BY THE EVENING. MODEL SIGNAL
HAS BEEN FAIRLY PERSISTENT IN ENOUGH 900-800MB MOISTURE TO SUPPORT A
FEW HUNDRED J/KG OF MUCAPE AND POSSIBLE HIGH BASED SHOWER ACTIVITY
FOR AREAS SOUTH OF DETROIT AFTER 22Z TUESDAY. MASS CENTROID TO
SURFACE BASED HIGH PRESSURE IN CANADA PASSES EAST OF THE
LONGITUDE/MERIDIAN HERE FOR SOUTHEAST MICHIGAN TUESDAY NIGHT. THE
COMBINATION OF INCREASING ANTICYCLONIC FLOW TRAJECTORIES AT THE
SURFACE AND A MARINE RELEASE OFF OF THE COLD GREAT LAKES WILL ALLOW
A SHALLOW COLD FRONT TO SLIP SOUTH OF SOUTHEAST MICHIGAN. THEREFORE,
EXPECTING COOLER CONDITIONS ON WEDNESDAY ESPECIALLY FOR THOSE
LOCATIONS NEAR LAKE HURON. LAKESHORE AREAS MAY STRUGGLE TO REACH THE
50S.
HIGH AMPLITUDE RIDGE THEN LEADS TO HIGH PREDICTABILITY FOR
CONSIDERABLE WARMING THURSDAY AND FRIDAY. HIGHS ARE EXPECTED TO BE
IN THE 70S DEPENDING ON NORTH TO SOUTH EXTENT. HIGH SOLUTION
VARIANCE CONTINUES TO EXIST NEXT WEEKEND AS A VERY COMPLEX UPPER
LEVEL PATTERN IS BEING ADVERTISED. THERE HAS BEEN A TON OF AGREEMENT
IN SUGGESTING CLOSED LOW/CUTOFF LOW POTENTIAL UPSTREAM OVER THE
GREAT PLAINS AND UPPER MISSISSIPPI RIVER VALLEY. PROGRESSION OF ANY
COLD OR OCCLUDED FRONTS WILL HAVE A MAJOR IMPACT ON THE SENSIBLE
WEATHER FORECAST. MOST UP TO DATE TIMING OF THE COLD FRONT IS LATE
FRIDAY NIGHT OR SATURDAY. DURATION OF PRECIPITATION IS VERY MUCH IN
QUESTION SATURDAY AND SUNDAY.
MARINE...
GUSTY NORTHWEST WIND WILL CONTINUE TO SUBSIDE THROUGH THE MORNING AS
HIGH PRESSURE EASES IN FROM THE WEST TODAY. SMALL CRAFT ADVISORIES
REMAIN IN EFFECT ALONG THE SOUTHERN LAKE HURON NEARSHORE WATERS
UNTIL LATE MORNING AS WAVE HEIGHTS WILL TAKE TIME TO DIMINISH. THE
CENTER OF THE HIGH PASSES OVER THE CENTRAL GREAT LAKES THIS
AFTERNOON AND EVENING WITH SOUTHERLY RETURN FLOW COMMENCING TONIGHT
AS THE HIGH DEPARTS EAST. STRONGER SOUTH TO SOUTHWEST WIND WILL
SPREAD OVER THE REGION TUESDAY MORNING INTO THE EARLY AFTERNOON, AND
ANOTHER ROUND OF SMALL CRAFT ADVISORIES WILL BE POSSIBLE. OVERLAKE
STABILITY WILL PREVENT MUCH OF THE HIGHER MAGNITUDE WIND FROM
REACHING THE SURFACE, BUT A PERIOD OF GUSTS TO 20 TO 25 KT LOOKS
LIKELY BETWEEN 4AM AND 2PM. A COLD FRONT THEN SETTLES SOUTHWARD
ACROSS THE REGION LATE IN THE DAY, BRINGING A CHANCE OF SHOWERS AND
THUNDERSTORMS BY TUESDAY NIGHT, MAINLY IN THE SOUTH. WEAKER WIND
FOLLOWS ON WEDNESDAY AS THE PRESSURE GRADIENT RELAXES AGAIN.
DTX WATCHES/WARNINGS/ADVISORIES
MI...FREEZE WARNING UNTIL 11 AM EDT THIS MORNING FOR MIZ053-060>063-
068>070-075-076-082-083.
LAKE HURON...SMALL CRAFT ADVISORY UNTIL 10 AM EDT THIS MORNING FOR LHZ421-
441>443.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....MV
DISCUSSION...CB
MARINE.......TF
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