470
FXUS63 KDTX 301833
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
233 PM EDT THU APR 30 2026
KEY MESSAGES
- A WAVE OF LOW PRESSURE WILL PASS THROUGH PORTIONS OF INDIANA AND
OHIO LATE TONIGHT BRINGING LIGHT RAIN, 40 TO 70% CHANCE, SOUTH OF
DETROIT.
- A FROST ADVISORY IS IN EFFECT 10 PM TONIGHT UNTIL 8AM FRIDAY FOR
MANY AREAS NORTH OF M 59 INCLUDING THE THUMB.
- AFTERNOON RAIN SHOWERS WILL AGAIN BE POSSIBLE FRIDAY AFTERNOON.
- A FREEZE WATCH IS IN EFFECT FOR ALL OF SOUTHEAST MICHIGAN MIDNIGHT
TO 9 AM SATURDAY FOR THE POTENTIAL OF TEMPERATURES DROPPING BELOW
FREEZING.
- A SLIGHT WARMING TREND IS EXPECTED SUNDAY AND MONDAY BEFORE A COLD
FRONT PUSHES THROUGH THE AREA MONDAY NIGHT.
DISCUSSION
LOW GEOPOTENTIAL HEIGHTS WILL PERSIST OVER EASTERN NORTH AMERICA FOR
AT LEAST THE NEXT 7 DAYS. EXTENDED GLOBAL DETERMINISTIC SOLUTIONS
LARGELY SUPPORT A MEAN UPPER LEVEL TROUGH AXIS FROM JAMES BAY
SOUTHWARD THROUGH PORTIONS OF LAKE HURON AND GEORGIAN BAY WHICH WILL
KEEP MUCH OF SOUTHEAST MICHIGAN WITHIN NORTHWEST FLOW ALOFT. LATEST
PROGS SUPPORT A VERY HIGH FREQUENCY OF LOW AMPLITUDE SHORTWAVE
ENERGY DIGGING INTO THE WESTERN AND CENTRAL GREAT LAKES KEEPING
CHANCE POPS UBIQUITOUS IN THE FORECAST.
DIURNAL, BOUNDARY LAYER CLOUDS ARE EXPECTED TO THIN OUT WITH LOSS OF
DAYTIME HEATING THIS EVENING. THIS SHOULD ALLOW FOR FALLING
TEMPERATURES INTO THE MIDDLE TO LOWER 30S THROUGH MIDNIGHT FOR MUCH
OF THE NORTHERN FORECAST BEFORE CLOUDS THICKEN SOUTH. BASED ON THE
TEMPERATURE FORECAST DECIDED TO GO WITH A FROST ADVISORY FOR MANY
AREAS ALONG AND NORTH OF THE M 59 CORRIDOR PARTICULARLY THE THUMB.
THE FIRST OF MANY SHORTWAVES IS FORECASTED TO PIVOT AROUND THE UPPER
LEVEL LOW THROUGH PORTIONS OF IL/IN/OH ATTENDANT TO A SIGNIFICANT
LOBE OF POTENTIAL VORTICITY. WITH CONVECTIVE
AUGMENTATION/STRENGTHENING LATER TODAY, THE ABSOLUTE VORTICITY
MAXIMUM IS DECENTLY WELL RESOLVED IN THE NWP. 850-700MB
FRONTOGENESIS IS NOW EXPECTED ALONG THE NORTHERN DEFORMATION AXIS
THAT WILL STRIPE THROUGH LENAWEE AND MONROE COUNTIES. HIGH
RESOLUTION DATA IS BULLISH ON PRECIPITATION AND DECIDED TO INCREASE
TO LIKELY POPS FOR AREAS SOUTH OF DETROIT. PRECIPITATION RATES WILL
AID IN WETBULB COOLING AND POSSIBLE COULD SEE FEW WET/MELTING
SNOWFLAKES MIX IN. AMBIENT GROUND MOISTURE WITH STEEP MIDLEVEL LAPSE
RATES WILL RESULT IN AN ENVIRONMENT CONDUCIVE FOR SHOWERS FRIDAY
AFTERNOON WITH AFTERNOON FORECAST SOUNDINGS SUGGESTING SOME
CONVECTIVE INSTABILITY BETWEEN 4.0 AND 12.0 KFT AGL.
WEAK SURFACE RIDGING IS FORECASTED TO BUILD OUT OF THE MID
MISSISSIPPI RIVER VALLEY INTO LOWER MICHIGAN FRIDAY NIGHT AND
SATURDAY. LIGHT FLOW AND A DRY LOWER ATMOSPHERIC COLUMN SUGGESTS
BETTER SUPPORT FOR RADIATIONAL COOLING. BASED ON FORECASTED
TEMPERATURES OF 30-32F FOR MUCH OF THE AREA DECIDED TO GO WITH A
FREEZE WATCH. LOWER CONFIDENCE EXISTS ON LOW TEMPERATURES FOR THE
URBAN HEAT ISLAND AREAS OF METRO DETROIT AS TEMPERATURES COULD
REMAIN IN THE MIDDLE 30S.
DAMPENED SHORTWAVE IN ADDITION TO SYNOPTIC SCALE WARM ADVECTION WILL
LEAD TO PRECIPITATION CHANCES AGAIN BY LATE SUNDAY. A TEMPORARY
SOUTHWEST FLOW REGIME IS EXPECTED TO SUPPORT TEMPERATURES NEAR 60
DEGREES SUNDAY WHICH IS SOME 10 DEGREES WARMER THAN THE DAY BEFORE.
THE CURRENT FORECAST HAS POPS DURING THE AFTERNOON AND SUNDAY NIGHT
WHICH IS SUFFICIENT.
SIGNIFICANT POLAR VORTICITY RESERVOIR AND UPPER LEVEL JET STREAK WILL
THEN CARVE OUT AND REESTABLISH THE TROUGHING OVER THE GREAT LAKES
DURING THE MONDAY AND TUESDAY TIMEFRAME NEXT WEEK. CURRENT
INDICATIONS SUGGEST A WET PERIOD ALONG A PREFRONTAL TROUGH LATE
MONDAY. TEMPERATURES MONDAY ARE EXPECTED TO BE APPROXIMATELY 5
DEGREES ABOVE NORMAL BEFORE A COLD FRONT LEADS TO CHILLY CONDITIONS
BY THE MIDDLE OF NEXT WEEK.
MARINE
THE GREAT LAKES REMAINS UNDER THE INFLUENCE OF A SLOW MOVING UPPER-
LEVEL LOW PRESSURE SYSTEM. PERIODIC ISOLATED TO SCATTERED SHOWERS
ARE EXPECTED THROUGH THE END OF THE WEEK, ALONG WITH LIGHTER WINDS
UNDER A MORE DIFFUSE PRESSURE GRADIENT. WIND DIRECTION HOLDS
NORTHWEST WITH STRONGER WINDS CONFINED NORTHERN LAKE HURON, WHERE
GUSTS AROUND 20 KNOTS WILL BE POSSIBLE.
PREV DISCUSSION
ISSUED AT 1258 PM EDT THU APR 30 2026
AVIATION...
BLOSSOMING DIURNAL CU COVERAGE EARLY THIS AFTERNOON AS ONGOING
NORTHWEST COLD ADVECTION SUPPORTS WEAK INSTABILITY. A FEW SCATTERED
SHOWERS HAVE BEEN SEEN ON RADAR NORTH OF I-69 DUE TO THIS DIURNAL
INSTABILITY HOWEVER OVERALL COVERAGE TODAY EXPECTED TO BE
SIGNIFICANTLY LESS THAN YESTERDAY'S. AS SUCH, LOW CONFIDENCE IN ANY
SINGLE TERMINAL SEEING A SHOWER TODAY WITH 'BEST CHANCES' FAVORED
FROM FNT NORTH. A COMPACT LOW PASSING OVER NORTHERN IN/OH TONIGHT
OFFERS A CHANCE FOR LIGHT SHOWERS AND LOW VFR TO BORDERLINE MVFR
CIGS OVER THE DETROIT TERMINALS TONIGHT. AREAS NORTH REMAIN DRY AND
PARTIALLY CLEAR OVERNIGHT- ESPECIALLY TOWARD MBS.
D21/DTW CONVECTION...NO THUNDERSTORMS EXPECTED THROUGH THIS TAF
PERIOD.
DTW THRESHOLD PROBABILITIES...
* HIGH FOR CEILING AT OR BELOW 5,000 FEET TODAY, MODERATE TONIGHT.
DTX WATCHES/WARNINGS/ADVISORIES
MI...FROST ADVISORY FROM 10 PM THIS EVENING TO 8 AM EDT FRIDAY FOR
MIZ047>049-053>055-061>063-069-070.
FREEZE WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY 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...CB
MARINE.......AM
AVIATION.....KDK
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