118
FXUS63 KDTX 290805 CCA
AFDDTX
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
405 AM EDT WED APR 29 2026
KEY MESSAGES
- SCATTERED LIGHT RAIN SHOWERS THIS MORNING.
- TEMPERATURES ROUGHLY 10 DEGREES BELOW AVERAGE THE REST OF THE
WEEK, BRINGING POTENTIAL FOR FROST/FREEZE CONDITIONS EACH
MORNING THRU SUNDAY.
DISCUSSION
A MID-LEVEL TROUGH PASSING THROUGH THE MIDWEST MERGES WITH A
CONVECTIVELY ENHANCED SHORTWAVE OVER THE OHIO VALLEY THIS MORNING.
THE RESULT WILL BE A DEEPENING SFC LOW THAT DEVELOPS ALONG THE
STALLED BAROCLINIC ZONE TO OUR SOUTH AND TRACKS INTO THE MID-
ATLANTIC REGION. THE DEEPER MOISTURE TRANSPORT WITH THIS SYSTEM WILL
BE SHUNTED TO THE SOUTH AND EAST, BUT WILL SEE POCKETS OF LIGHT
SHOWERS TRACK THROUGH THIS MORNING AS TRANSIENT FGEN EXCITES THE 600-
700MB FRONT OVERHEAD. HIGHEST CONFIDENCE IN MEASURING AROUND 0.10"
WILL BE SOUTH OF METRO DETROIT WHERE THE MOST ORGANIZED FORCING AND
DEEPEST MOISTURE IS PROGGED TO SET UP.
LOW-LEVEL DRY AIR IS SHOWN TO SPREAD BACK IN FROM THE NORTH AS THE
ELEVATED FORCING PEELS AWAY MIDDAY, FAVORING MAINLY DRY CONDITIONS
EAST OF US-23 THE REST OF THE AFTERNOON. AS PVA ASSOCIATED WITH THE
MIDWEST TROUGH TRACKS IN LATE AFTERNOON AND THIS EVENING, ADDITIONAL
SPOTTY SHOWERS EXPAND IN COVERAGE OVER INTERIOR LOWER MI AND PERSIST
INTO PARTS OF TONIGHT. THIS WAVE PASSING THROUGH ALSO PRODUCES A
HEALTHY COVERAGE OF LOWER CLOUD OVERNIGHT, WHICH WITH A WEAK
GRADIENT WIND IS FORECAST TO PREVENT WIDER DEVELOPMENT OF FROST.
SOME PATCHY FROST STILL POSSIBLE AS 2M TEMPS SETTLE INTO THE MID 30S
OUTSIDE OF URBAN AREAS.
THE TROUGH STALLS OVER THE NORTHERN GREAT LAKES TONIGHT, EVOLVING
INTO A CLOSED LOW THAT MEANDERS OVER THE REGION THE REST OF THE
WEEK. COOL NORTHWEST FLOW DOMINATES LOCAL CONDITIONS WITH TEMPS
FALLING ROUGHLY 10 DEGREES BELOW AVERAGE FOR LATE APRIL AND EARLY
MAY. MOSTLY BENIGN CONDITIONS DURING THIS PERIOD, BUT EXPECT A DAILY
FLARE-UP OF SHOWERS AS THE COLD POOL ALOFT INDUCES STEEP LAPSE RATES
WITHIN THE BROAD MOIST CYCLONIC FLOW. DAILY HIGHS WITHIN A FEW
DEGREES OF 50 FAVOR RAIN SHOWERS BUT WET SNOWFLAKES POSSIBLE AT
TIMES AS WET BULB ZERO HEIGHTS FALL BELOW 2KFT.
THE UPCOMING COOL PERIOD IS UNCOMMON BUT NOT COMPLETELY UNHEARD OF
FOR EARLY MAY, WITH HISTORICAL DATA SHOWING TEMPS FALLING BELOW
FREEZING DURING THE FIRST WEEK OF MAY ROUGHLY ONCE EVERY 3 TO 7
YEARS ON AVERAGE. HOWEVER, WITH THE WARM SPRING SO FAR - RANKED IN
THE TOP-10 WARMEST UP TO THIS POINT FOR MOST SITES IN SE MI - THIS
COLD COMES WITH POTENTIAL IMPACTS TO SENSITIVE VEGETATION. FRIDAY,
SATURDAY, AND SUNDAY MORNING REMAIN TARGETS FOR POTENTIAL
FROST/FREEZE HEADLINES, PARTICULARLY SATURDAY MORNING. IF THE
CURRENT FORECAST FOR LOWS IN THE UPPER 20S SATURDAY MORNING
VERIFIES, SOME LOW MIN RECORDS WILL BE WITHIN REACH.
THE THERMAL TROUGH IS NUDGED OUT EARLY NEXT WEEK WHICH FAVORS A
SLIGHT WARM-UP, BUT LONGWAVE TROUGHING REMAINS THE DOMINANT PATTERN
OVER THE EASTERN CONUS WELL INTO NEXT WEEK. THIS OFFERS SEVERAL
OPPORTUNITIES FOR WIDESPREAD PRECIP EVENTS, AND TEMPS GENERALLY NEAR
OR BELOW NORMAL. CPC 6-10 DAY, 8-14 DAY, AND WEEK 3-4 OUTLOOKS
MAINTAIN A LEAN TOWARD CHILLY CONDITIONS WELL INTO THE MONTH OF MAY.
MARINE
A MORE DIFFUSE SURFACE PRESSURE FIELD EMERGES TODAY AS THE CENTRAL
GREAT LAKES BECOMES POSITIONED BETWEEN SEVERAL WEAK SURFACE HIGH
PRESSURE AREAS TO THE WEST. MID-LEVEL TROUGHING PERSISTS OVERHEAD,
LIFTING A WEAK SURFACE LOW THROUGH THE OHIO VALLEY. THIS LENDS
POTENTIAL FOR PERIODS OF LIGHT SHOWERS, BUT A LACK OF INSTABILITY
PRECLUDES THUNDERSTORM CONCERNS. LOCAL WINDS GENERALLY HOLD FROM THE
NORTHWEST THROUGH THE REST OF THE WORKWEEK WITH SOME ADDITIONAL
CHANCES FOR WEAKLY FORCED LIGHT PRECIPITATION. STRONGER HIGH PRESSURE
THEN ATTEMPTS TO BUILD IN FROM CENTRAL CANADA/CONUS OVER THE
WEEKEND. LOW PREDICTABILITY EXISTS IN THE LARGE-SCALE PATTERN
EVOLUTION THIS WEEKEND AS STALLED LOW PRESSURE OVER THE NORTHEAST
RETROGRADES TOWARD THE GREAT LAKES. NO MARINE HEADLINES ARE EXPECTED
THROUGH SATURDAY GIVEN CURRENT WIND AND WAVE TRENDS.
PREV DISCUSSION
ISSUED AT 1158 PM EDT TUE APR 28 2026
AVIATION...
LATE EVENING OBSERVATIONS INDICATE VFR UNDER INCREASING MID AND HIGH
CLOUDS OVER LOWER MI AS A WEAK SURFACE PRESSURE TROUGH FINISHES
RELEASING OFF LAKE HURON WITH A NORTHERLY WIND SHIFT. UPSTREAM
OBSERVATIONS ACROSS THE MID MS VALLEY THEN INDICATE TRENDS ARE ON
SCHEDULE FOR THE LATE NIGHT AND MORNING. LOW PRESSURE SLIDING ALONG
THE STALLED OHIO VALLEY FRONT IS THE SURFACE REFLECTION OF A MID
LEVEL WAVE THAT GRAZES LOWER MI WITH POCKETS OF LIGHT RAIN SHOWERS
AFTER SUNRISE. 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 WHILE SHOWER COVERAGE STRUGGLES TO
MAINTAIN COVERAGE AND INTENSITY, AND AS THE LOW LEVEL WIND TURNS NE
AHEAD OF THE OHIO VALLEY SURFACE LOW. EASTWARD PASSAGE OF THE LOW
LEAVES WIDELY SCATTERED SHOWERS IN THE AFTERNOON MAINLY WEST OF THE
TERMINAL CORRIDOR 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 LATE TONIGHT. MODERATE IN THE
MORNING. HIGH WEDNESDAY AFTERNOON AND EVENING.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
DISCUSSION...TF
MARINE.......KGK
AVIATION.....BT
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