937
FXUS63 KDTX 282318
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
718 PM EDT TUE APR 28 2026
KEY MESSAGES
- RAIN SHOWER CHANCES RETURN WEDNESDAY MORNING TO EARLY AFTERNOON.
- MUCH COLDER AIR ARRIVES BY LATE WEEK AND HOLDS THROUGH THE WEEKEND
RESULTING IN FROST/FREEZING POTENTIAL.
AVIATION
INBOUND DRY AIR AND PEAK BOUNDARY LAYER MIXING MADE GOOD PROGRESS ON
DECREASING LOW CLOUDS DURING LATE AFTERNOON INTO EARLY THIS EVENING.
THIS CONTINUES TO SUPPORT VFR CLEAR TO SCATTERED COVERAGE WHILE THE
SURFACE COLD FRONT STALLS IN THE OHIO VALLEY AND ANOTHER WAVE OF LOW
PRESSURE TRACKS ALONG IT LATER TONIGHT. THE FRONTAL ZONE IS SHALLOW
AND SLOPES BACK INTO SOUTHERN LOWER MI AROUND THE 700 MB LEVEL WHICH
BECOMES INCREASINGLY ACTIVATED BY VFR CLOUDS AND CLUSTERS OF RAIN
SHOWERS AS THE MID LEVEL WAVE MOVES IN FROM THE MO VALLEY. PROSPECTS
FOR MVFR CEILING ARE GREATER EARLY IN THE MORNING WHEN SHOWER
COVERAGE PEAKS AND LOW LEVEL WIND TURNS NE AHEAD OF THE OHIO VALLEY
SURFACE LOW. WIDELY SCATTERED SHOWERS LINGER IN THE AFTERNOON WITH
LOW PREDICTABILITY AT THE TERMINALS WHILE LOWER RANGE VFR CEILING
HOLDS INTO WEDNESDAY EVENING.
D21/DTW CONVECTION...NO THUNDERSTORMS EXPECTED THROUGH THIS TAF
PERIOD.
DTW THRESHOLD PROBABILITIES
* LOW FOR CEILING 5000 FEET OR LESS THIS EVENING. MODERATE LATE
TONIGHT. HIGH WEDNESDAY.
PREV DISCUSSION
ISSUED AT 247 PM EDT TUE APR 28 2026
DISCUSSION...
LOCALIZED MID-UPPER LEVEL POSITIVELY TILTED TROUGH AXIS CURRENTLY
LIFTING IN QUEBEC HAS ALLOWED FOR A TEMPORARY BOUT OF 1000-500MB
GEOPOTENTIAL HEIGHT RISES OVER SOUTHEAST MICHIGAN THIS AFTERNOON.
PLAN VIEW PERSPECTIVE OF SATURATION ON ISENTROPIC SURFACES SUPPORTS
STEEPER ISENTROPIC DOWNGLIDE AND GREATER ABSOLUTE DRY AIR ADVECTION
OCCURING AFTER 18Z. WITH THE DRIER AIR AND MATURE BOUNDARY LAYER
LATE EXPECTATIONS ARE FOR A TEMPORARY CLEARING TREND THIS EVENING.
TEMPERATURES SHOULD QUICKLY FALL INTO THE UPPER 40S TO LOWER 50S BY
THE LATE EVENING.
COMBINATION OF APPROACHING COMPOSITE TROUGH AXIS WITH EMERGING LEFT
EXIT REGION DYNAMICS OFF OF SOUTHERN STREAM JET STREAK WILL PROVIDE
SYNOPTIC SCALE SUPPORT FOR OHIO RIVER VALLEY LOW PRESSURE SYSTEM
LATE TONIGHT AND WEDNESDAY. WHILE A SIGNAL EXISTS IN THE MOISTURE
PROGS FOR SATURATION AND BAROCLINIC LEAFING WITHIN THE 850-500MB
LAYER EXTENDING UP INTO SOUTHEAST MICHIGAN, NO SIGNIFICANT
FRONTOGENESIS IS PROGGED LOCALLY ACROSS SOUTHEAST MICHIGAN. AS A
RESULT, THIS IS EXPECTED TO BE A LOW QPF EVENT WITH PERHAPS A TENTH
OR TWO POSSIBLE SOUTH OF DETROIT. NO BIG CHANGES ARE ANTICIPATED TO
THE GRIDDED FORECAST WHICH HAS POPS AT 40--60% CHANCE MAINLY BETWEEN
08-18Z.
A LARGE UPPER LEVEL CLOSED LOW PRESSURE SYSTEM AND TROUGHING IS
FORECASTED TO TAKE RESIDENCE AND PERSIST OVER AREAS FROM LAKE
SUPERIOR NORTHWARD TO QUEBEC AND JAMES BAY FROM THURSDAY THROUGH AT
LEAST THE END OF THE PERIOD MONDAY. THE COLDEST STRETCH IS
ANTICIPATED FRIDAY AND SATURDAY WITH 850MB TEMPERATURES OF -6 TO -
7C. FROST AND FREEZE HEADLINES WILL AT LEAST NEED TO BE CONSIDERED
WEDNESDAY THROUGH SATURDAY NIGHTS WITH LOWS EXPECTED TO BE IN THE
UPPER 20S TO LOWER 30S. PERSISTENT TROUGHING WILL BRING STEEP
MIDLEVEL LAPSE RATES AND A GOOD PATTERN FOR AFTERNOON PRECIPITATION
CHANCES. MOST DAYS WILL SEE A CHANCE OF RAIN, HOWEVER, THURSDAY
AFTERNOON COULD SEE A FEW WET SNOWFLAKES ACROSS THE THUMB REGION AS
THE ABSOLUTE VORTICITY MAXIMUM AND COLD AIR ALOFT EMERGES OUT ON LAKE
HURON.
MARINE...
EXITING SURFACE LOW PRESSURE CONTINUES ACROSS JAMES BAY INTO
NORTHERN QUEBEC TONIGHT, CAUSING THE PRESSURE GRADIENT TO STEADILY
RELAX. THIS EVENTUALLY LEADS TO WEAKER WINDS, VEERING
ANTICYCLONICALLY TOWARD THE NORTH. REMAINING SMALL CRAFT ADVISORY
SHOULD EXPIRE ON-SCHEDULE AS WINDS/WAVES RESPOND TO DECREASING FLOW
INTO THE EVENING HOURS. A MORE DIFFUSE SURFACE PRESSURE FIELD
EMERGES ON WEDNESDAY AS THE CENTRAL GREAT LAKES BECOMES POSITIONED
BETWEEN SEVERAL WEAK SURFACE HIGH PRESSURE CENTERS TO THE WEST. MID-
LEVEL TROUGHING LIKELY PERSISTS OVERHEAD ON WEDNESDAY WITH A WEAK
SURFACE REFLECTION LIFTING THROUGH THE OHIO VALLEY. THIS LENDS
POTENTIAL FOR PERIODS OF LIGHT SHOWERS, BUT A LACK OF INSTABILITY
PRECLUDES ANY THUNDERSTORM CONCERNS. WATER-LEVEL WINDS GENERALLY
HOLD NORTHWESTERLY THROUGH THE REST OF THE WORKWEEK WITH ADDITIONAL
CHANCES FOR WEAKLY FORCED LIGHT PRECIPITATION. HIGH PRESSURE THEN
ATTEMPTS TO BUILD IN FROM CENTRAL CANADA/CONUS OVER THE WEEKEND. LOW
PREDICTABILITY EXISTS IN THE LARGE-SCALE PATTERN EVOLUTION AS
EASTERN CANADA LOW PRESSURE RETROGRADES TOWARD THE GREAT LAKES. NO
ADDITIONAL MARINE HEADLINES ARE EXPECTED THROUGH SATURDAY GIVEN
LATEST WIND/WAVE TRENDS.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR LHZ421-422.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....BT
DISCUSSION...CB
MARINE.......KGK
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