034
FXUS63 KDTX 020747
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
347 AM EDT SAT MAY 2 2026
KEY MESSAGES
- A FREEZE WARNING WILL EXPIRE AT 9 AM TODAY.
- MAINLY DRY AND COOL TODAY, WITH AN ISOLATED AFTERNOON SHOWER OR TWO
POSSIBLE AND HIGHS IN THE 50S.
- BREEZIER WITH MODERATING TEMPERATURES AND SOME SCATTERED SHOWERS
SUNDAY.
- ABNORMALLY WARM MONDAY WITH CHANCES FOR SHOWERS AND SOME EMBEDDED
THUNDERSTORMS, MORE SO LATE MONDAY INTO TUESDAY.
DISCUSSION
A STALLED UPPER LOW PARKED ALONG THE ONTARIO/QUEBEC BORDER UNLOCKS
TODAY LEADING TO A GRADUAL SHIFT TOWARD ANTICYCLONICALLY
CURVED/SUBSIDENT FLOW. DRIER LOW-LEVEL AIR IS ACTIVELY WORKING IN
FROM THE NORTHWEST, HELPING TO SCOUR OUT THE RESIDUAL STRATOCUMULUS
DECK. HOWEVER, THE DELAY IN CLEARING HAS RESULTED IN NOCTURNAL
COOLING LAGGING FORECASTED VALUES. AS FOR THE FREEZE WARNING, THE
COVERAGE AND DURATION OF SUB-32F CONDITIONS HAVE TRENDED LOWER. THE
HIGHEST CONFIDENCE IN MEETING CRITERIA EXISTS WITH NORTHWESTWARD
EXTENT, WHERE CLEAR SKIES EMERGE THE EARLIEST. TIMING OUT THE
CLEARING LINE OF THE TRAILING 8 KFT LAYER SUGGESTS CLOUDS MAY STILL
BE OVER DOWNTOWN DETROIT AFTER 12Z. FOR CONSISTENCY, AND TO ACCOUNT
FOR LOCALIZED EFFECTS, THE HEADLINE WILL REMAIN IN-PLACE UNTIL 13Z
FOR ALL OF SOUTHEAST MICHIGAN, BUT THE TRI-COUNTY AREA (OAKLAND,
WAYNE, MACOMB) AND THOSE ALONG THE MICHIGAN/OHIO BORDER SHOULD
EXPECT MORNING TEMPERATURES TO PREDOMINANTLY MINIMIZE IN THE MID 30S.
ONCE THE REGION FULLY CLEARS OUT LATER THIS MORNING, DIURNAL CLOUDS
EVENTUALLY FILL IN DURING THE AFTERNOON HOURS AS THE BOUNDARY LAYER
MATURES. FORECAST SOUNDINGS SHOW SIMILARLY DEEP MIXING POTENTIAL
(COMPARED TO YESTERDAY), BUT THE SATURATION/CLOUD-BEARING LAYER
APPEARS SHALLOWER (LESS THAN 3 KFT), MARKED BY PWATS DROPPING BELOW
A THIRD OF AN INCH. PAIRED WITH DRY AIR ALOFT, EXPECT A MOSTLY DRY
DAY, EVEN AS THE NEXT LOBE OF MID-LEVEL CVA MOVES THROUGH. COULD
STILL SEE A FEW ISOLATED SHOWERS TRY TO DEVELOP ON RADAR, BUT
RETURNS SHOULD LARGELY REFLECT THE SAMPLING OF VIRGA. AT THE
SURFACE, DIFFUSE HIGH PRESSURE SPILLS ACROSS SOUTHERN LOWER WITH
WEAK NORTHWESTERLY GRADIENT FLOW. IN SPITE OF THE SEASONABLY CHILLY
START AND 700 MB TEMPERATURES IN THE MINUS TEENS (CELSIUS), DAYTIME
HIGHS SHOULD RECOVER INTO THE LOWER 50S, AIDED BY RISING MAY SUN
ANGLE.
LOCAL HEIGHT RISES STRUGGLE TO BECOME WELL-ESTABLISHED ON SUNDAY AS
PERTURBED FLOW, DOWNSTREAM OF SEVERAL INBOUND CENTRAL CANADIAN
SHORTWAVE IMPULSES, SHEARS OUT THE PASSING RIDGE AXIS. STANDARD
DEEPENING TROUGH CADENCE THEN UNFOLDS WITH THE INITIAL GEOPOTENTIAL
HEIGHT REDUCTION EMERGING WITHIN THE LOWER PORTION OF THE
TROPOSPHERE. THIS BACKS WINDS SOUTHWESTERLY, DRAWING MILDER AIR INTO
THE GREAT LAKES WITHIN AN ELEVATED WARM SECTOR. ONCE THE SURFACE
WARM FRONT LIFTS IN, GRADIENT WINDS STRENGTHEN AS THE FORECAST AREA
GETS WEDGED BETWEEN BROAD SURFACE HIGH PRESSURE OVER THE SOUTHEAST
AND A COMPARATIVELY WEAKER SURFACE TROUGH TRAVERSING THE NORTHERN
LAKES. LOW-LEVEL JET WINDS OF 35-45 KNOTS MOVE IN SUNDAY AFTERNOON,
AND WITH SURFACE WARMING OUTPACING THERMAL MODERATION ALOFT, NEUTRAL
TO WEAKLY UNSTABLE PROFILES SHOULD ALLOW FOR OCCASIONAL GUSTS OF 30-
40 MPH DURING THE AFTERNOON HOURS. ADDITIONALLY, EXPECT SOME SHOWERS
TO DEVELOP AS MOISTURE TRANSPORT INCREASES DURING THE AFTERNOON AND
EVENING HOURS GIVEN INCREASING CONFLUENCE WITHIN THE LOWER LEVELS.
RAINY CONDITIONS COULD PERSIST THROUGH PART OF THE OVERNIGHT PERIOD.
LONGER WAVELENGTH TROUGHING FROM WESTERN CANADA PHASES WITH THE
RETROGRADING RESIDENT UPPER LOW AND DIGS INTO THE UPPER MIDWEST
MONDAY AND TUESDAY. THE COMPOSITE WAVE POSITIONED WITHIN THE POLAR
JET LEADS TO AN INCREASING TENDENCY FOR ASCENT AS WARM ADVECTION
BUILDS MONDAY (HIGHS +70F), BUT THE FORECAST JET STREAK PATH DOES
NOT FAVOR STRONG OVERLAP FOR UPPER-LEVEL DIVERGENCE. INSTABILITY
STRUGGLES TO LIFT IN FROM THE OHIO VALLEY WITH DEWPOINTS STILL BELOW
50F BY SUNSET MONDAY. WARM SECTOR SHOWERS/THUNDERSTORM POTENTIAL
APPEARS LOW GIVEN FORMIDABLE CAPPING AND DRY LAYERING, THUS THE
BETTER CHANCE FOR MORE WIDESPREAD QPF WILL BE ASSOCIATED WITH THE
SYSTEM'S COLD FRONTAL PASSAGE MONDAY NIGHT INTO TUESDAY. THE WAVE
OCCLUDES AS IT APPROACHES JAMES BAY (NEAR 985 MB) WHILE THE
SECONDARY LOW/FRONT DRIVES MICHIGAN SHOWERS WITH EMBEDDED THUNDER.
STEEP MID-LEVEL COOLING/LAPSE RATES REFLECT DETERMINISTIC 02.00Z
NAM/GFS SOLUTIONS WITH 1500+ J/KG OF MUCAPE, BUT 200+ J/KG OF CIN
EXIST BELOW THE ELEVATED INSTABILITY. SHOULD ANY STORMS DEVELOP
ABOVE THE CAPPING INVERSION, A NOCTURNAL LARGE HAIL THREAT WOULD BE
THE MAIN CONCERN. UNSETTLED CONDITIONS LINGER MID-WEEK AS THE
BOUNDARY SLOWS TO A CRAWL AND TEMPERATURES STEADILY COOL DOWN BELOW
CLIMATOLOGICAL NORMALS.
MARINE
A LARGE AND SLOW MOVING UPPER LEVEL LOW WILL EXIT THE REGION TODAY
AS A BROAD AREA OF HIGH PRESSURE ENTERS THROUGH THE DAY. THIS
COMBINATION WILL LEAD TO A FAIRLY QUIET STRETCH OF MARINE WEATHER
WITH MAINLY CLOUDS AND LIGHT WINDS (GUSTS UNDER 15 KNOTS) THROUGH
TONIGHT WITH AN OPPORTUNITY FOR A LIGHT SHOWER MAINLY IN THE
AFTERNOON HOURS. NORTH TO NORTHWEST FLOW BACKS TO THE SOUTHWEST
TOMORROW AND HOLDS THROUGH EARLY NEXT WEEK AS A WARM FRONT PASSES
THROUGH THE GREAT LAKES. GUSTS TOMORROW COULD REACH 25 KNOTS ON
BEHIND THE FRONT IN SOME OF THE NEARSHORE ZONES, PARTICULARLY
THROUGH THE SAGINAW BAY. THERE WILL BE ADDITIONAL CHANCES FOR RAIN
SHOWERS AND A LOW CHANCE FOR AN EMBEDDED THUNDERSTORM EARLY NEXT
WEEK.
PREV DISCUSSION
ISSUED AT 1155 PM EDT FRI MAY 1 2026
AVIATION...
VARIABLE WINDS HAVE DEVELOPED ACROSS THE AIRSPACE TONIGHT IN
RESPONSE TO THE INLAND EXPANSION OF THE MARINE LAYER, WITH MANY
SITES REPORTING EAST-NORTHEAST WINDS. LOW VFR DECK REMAINS IN PLACE
CURRENTLY, BUT ERODES OVERNIGHT AS UPSTREAM DRY AIR FILLS IN. HIGH
PRESSURE EXPANDS INTO THE OHIO VALLEY SATURDAY, AFFORDING A PERIOD
OF CLEARING IN THE MORNING BEFORE DIURNAL CU REDEVELOPS. LIGHT
NORTHWEST WINDS BACK TO THE SOUTHWEST SATURDAY EVENING AS THE HIGH
WEAKENS AND DRIFTS EAST.
D21/DTW CONVECTION...NO THUNDERSTORMS EXPECTED THROUGH THIS TAF
PERIOD.
DTW THRESHOLD PROBABILITIES...
* LOW FOR CEILINGS AT OR BELOW 5000 FEET TONIGHT AND LATE SATURDAY
MORNING.
DTX WATCHES/WARNINGS/ADVISORIES
MI...FREEZE WARNING UNTIL 9 AM EDT THIS MORNING FOR MIZ047>049-053>055-
060>063-068>070-075-076-082-083.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
DISCUSSION...KGK
MARINE.......DRK/AM
AVIATION.....MV
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