198
FXUS63 KDTX 171109
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
709 AM EDT FRI APR 17 2026
KEY MESSAGES
- A DENSE FOG ADVISORY IS IN EFFECT THROUGH 10 AM FOR ALL OF SE
MICHIGAN.
- DRY TODAY BEFORE A STRONG COLD FRONT BRINGS RAIN AND A FEW
THUNDERSTORMS LATE TONIGHT INTO SATURDAY MORNING.
- BREEZY AND MUCH COLDER SUNDAY WITH A FEW LAKE SHOWERS MIXING WITH
WET SNOWFLAKES AT TIMES.
- SEASONABLY COLD MONDAY MORNING WITH WIND CHILLS IN THE LOW 20S AND
FREEZE CONDITIONS INCREASINGLY LIKELY.
AVIATION
HIGH AMBIENT MOISTURE, NIL WINDS AND CLEAR SKIES LED TO THE
WIDESPREAD DEVELOPMENT OF VLIFR FOG ACROSS SOUTHEAST MICHIGAN
OVERNIGHT. INSOLATION IS EXPECTED TO IMPROVE SURFACE CONDITIONS BY
14-15Z THIS MORNING. LOW CONFIDENCE EXISTS IN THE DURATION OF LOW
CEILINGS BEYOND. A LINE OF THUNDERSTORMS WILL PUSH ACROSS SOUTHEAST
MICHIGAN TONIGHT BETWEEN 9-12Z.
DTW/D21 CONVECTION...LOW CONFIDENCE ON WHEN CEILINGS WILL LIFT THIS
MORNING. THUNDERSTORMS ARE EXPECTED TONIGHT BETWEEN 9-12Z.
DTW THRESHOLD PROBABILITIES
* MEDIUM FOR CEILINGS AOB 5000 FT EARLY TONIGHT.
* HIGH FOR CEILINGS BELOW 200FT OR VISIBILITIES BELOW 1/2SM THIS
MORNING.
* HIGH FOR THUNDERSTORMS TONIGHT BETWEEN 9-12Z.
PREV DISCUSSION
ISSUED AT 348 AM EDT FRI APR 17 2026
DISCUSSION...
DENSE FOG HAS BEEN EXPANDING INLAND OVERNIGHT FROM BOTH LAKE
MICHIGAN AND LAKE HURON. STRONG ISENTROPIC DOWNGLIDE HAS ESTABLISHED
A DRY AND STATICALLY STABLE AIRMASS ALOFT, EFFICIENTLY TRAPPING
MOIST BOUNDARY LAYER CONDITIONS CHARACTERIZED BY DEWPOINTS STILL IN
THE LOW 50S. NEARLY ALL SITES ARE NOW REPORTING 1/4 TO 1/2 MILE
VISIBILITY. A DENSE FOG ADVISORY HAS BEEN ISSUED FOR ALL OF SE
MICHIGAN AS A RESULT. THE FOG LAYER LIFTS TO A STRATUS DECK WITH THE
START OF THE DIURNAL CYCLE BEFORE SCATTERING OUT THIS AFTERNOON.
BRIEF PERIOD OF MID-LEVEL RIDGING/HEIGHT RISES AFFORDS A PLEASANT
SPRING DAY ACROSS SE MICHIGAN, AS DAYTIME HIGHS CLIMB INTO THE UPPER
60S TO LOW 70S. SHOULD SEE A PRONOUNCED MARINE INFLUENCE ON HIGHS
FOR THE EAST SIDE OF THE CWA WHERE EAST FLOW OFF THE LAKES KEEPS
TEMPERATURES SEVERAL DEGREES COOLER THAN INLAND LOCATIONS. DRY
WEATHER IS EXPECTED AMIDST A MUCH DRIER AIRMASS IN COMPARISON TO THE
LAST FEW DAYS, AS PWATS FALL TO AROUND 0.5".
QUIET CONDITIONS ARE SHORT-LIVED WITH THE NEXT ROUND OF
RAIN/THUNDERSTORMS EXPECTED LATE TONIGHT-SATURDAY. CONVECTION
INITIATES OVER WI/IA THIS AFTERNOON ALONG A STRONG COLD FRONT,
PROPAGATING INTO THE INSTABILITY PLUME THAT SPILLS INTO WESTERN
LOWER MICHIGAN THIS EVENING. HI-RES CONSENSUS HAS THIS LINE
OUTRUNNING THE INSTABILITY AXIS BY THE TIME IT REACHES SE MICHIGAN
(AFTER 06Z/2AM LOCAL) WHICH KEEPS THE SWODY1 RISK TO OUR WEST. ANY
INSTABILITY THAT DOES ADVECT INTO THE AREA REMAINS WEAK AND
ELEVATED, FAVORING MOSTLY SHOWERS WITH SOME EMBEDDED/DECAYING
THUNDERSTORMS MOST LIKELY WEST OF I-75/US-23. ORGANIZED SEVERE
WEATHER IS NOT EXPECTED AT THIS TIME. A DISCUSSION OF HEAVY RAIN
POTENTIAL CAN BE FOUND IN THE HYDROLOGY SECTION. A SECOND FINE LINE
OF CONVECTION IS POSSIBLE SATURDAY MORNING ALONG THE COLD FRONTAL
PASSAGE ITSELF. THIS IS A SNEAKIER SET UP THAT LACKS DEEP CONVECTIVE
POTENTIAL, BUT OCCURS IN THE BACKDROP OF STRONG SYNOPTIC LIFT, LOW
LEVEL WIND SHEAR, AND STEEP LOW LEVEL LAPSE RATES. THINKING THIS
COULD MANIFEST AS A THUNDERLESS LINE OF CONVECTION THAT COULD
MECHANICALLY MIX GUSTY WINDS (40 KNOT LLJ AT H8) TO THE SURFACE. THE
FRONT WILL ALSO BE CHARACTERIZED BY A SHARP DROP IN TEMPERATURES.
HIGHS IN THE MID TO UPPER 60S OCCUR MID-MORNING FOLLOWED BY FALLING
TEMPERATURES THROUGH THE AFTERNOON. THE COLD ADVECTION INCREASES
MIXING DEPTHS TO CONTINUE TO TAP INTO THE LLJ WINDS, MAINTAINING
BREEZY CONDITIONS FOR THE REST OF THE WEEKEND.
A MUCH COOLER AIRMASS SETTLES IN FOR SUNDAY AND MONDAY AS THE PARENT
LOW DEEPENS AND SENDS AN ELONGATED LOBE OF VORTICITY ACROSS THE
GREAT LAKES. THIS DRAWS THE THERMAL TROUGH EVEN FURTHER SOUTH
ALLOWING H8 TEMPERATURES TO DROP INTO THE NEGATIVE SINGLE DIGITS
SUNDAY AND THE NEGATIVE TEENS MONDAY MORNING. HIGHS IN THE 40S
EXPECTED BOTH DAYS, WHILE THE COLDEST PERIOD WILL BE MONDAY MORNING
AS LOWS DIP INTO THE 20S. SEVERAL ADDITIONAL SHORTWAVES RIPPLE
ACROSS THE GREAT LAKES WITH BROAD TROUGHING SETTLING IN THROUGH
MONDAY. A FEW SHOWERS ARE POSSIBLE IN THIS PATTERN, WITH POTENTIAL
FOR WET SNOWFLAKES TO MIX IN WITH RAIN DUE TO THE COOL WET BULB
PROFILES. THAT SAID, LOW COVERAGE AND INTENSITY TO SHOWER ACTIVITY
IS EXPECTED GIVEN AN OVERALL LACK OF COLUMN MOISTURE. A WARM UP IS
THEN EXPECTED TUESDAY ONWARD WITH THE RETURN OF SOUTHWEST FLOW.
MARINE...
DENSE FOG ADVISORIES ARE IN EFFECT THROUGH MID MORNING BEFORE FOG
GRADUALLY IMPROVES THROUGH THE LATTER HALF OF THE MORNING AND
AFTERNOON. REGION HOLDS UNDER HIGH PRESSURE TODAY MAINTAINING A
BRIEF PERIOD OF DRY CONDITIONS AND LIGHTER WINDS. WINDS EVENTUALLY
ORGANIZE AND STRENGTHEN OUT OF THE SOUTHEAST THIS EVENING IN
RESPONSE TO LOW PRESSURE TRACKING INTO NORTHERN ONTARIO. MODERATE
SOUTHERLY WINDS WITH PEAK GUSTS IN THE 25-30KT RANGE EXPECTED
TONIGHT BEFORE FLIPPING TO THE WEST-NORTHWEST DAYTIME SATURDAY WITH
THE PASSAGE OF A RESPECTABLE COLD FRONT. GUSTS ALONG/IMMEDIATELY
FOLLOWING THE FRONT TOP OUT AROUND 30KTS. ANOTHER ROUND OF SHOWERS
AND THUNDERSTORMS ARE LIKELY IN ADVANCE OF SAID FRONT. CORE OF THE
COLDER TRAILING AIRMASS ARRIVES SUNDAY REINVIGORATING NORTHWESTERLY
WINDS SUPPORTING ANOTHER PERIOD OF GUSTS AROUND 30KTS. WHILE A
COUPLE GUSTS NEAR GALES ARE POSSIBLE, OVERALL POTENTIAL REMAINS LOW
(<30%). STRONG HIGH PRESSURE THEN SLIDES ACROSS THE CENTRAL GREAT
LAKES FOR MONDAY.
HYDROLOGY...
A STRONG COLD FRONT TRACKS ACROSS SE MICHIGAN LATE TONIGHT INTO
SATURDAY MORNING LEADING TO ANOTHER ROUND OF RAIN AND EMBEDDED
THUNDERSTORMS. BASIN WIDE RAINFALL AMOUNTS OF A HALF INCH TO
LOCALIZED ONE INCH ARE POSSIBLE BETWEEN LATE TONIGHT AND MID-DAY
SATURDAY. THIS ADDITIONAL RAIN WILL FALL ON ALREADY SATURATED SOILS
AND RISING AREA RIVERS, WORSENING EXISTING PONDING AND/OR FLOODING.
ADDITIONAL RISES ON AREA RIVERS WILL BE POSSIBLE, WITH SEVERAL
RIVERS ALREADY IN FLOOD STAGE (SAGINAW, TITTABAWASSEE, CASS).
DTX WATCHES/WARNINGS/ADVISORIES
MI...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR MIZ047>049-
053>055-060>063-068>070-075-076-082-083.
LAKE HURON...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR LHZ361>363-421-
422-441>443-462>464.
SMALL CRAFT ADVISORY FROM 4 AM TO 10 PM EDT SATURDAY FOR LHZ421-422.
SMALL CRAFT ADVISORY FROM 4 AM TO 4 PM EDT SATURDAY FOR LHZ441>443.
LAKE ST CLAIR...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR LCZ460.
MICHIGAN WATERS OF LAKE ERIE...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR LEZ444.
AVIATION.....CB
DISCUSSION...MV
MARINE.......KDK
HYDROLOGY....MV
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AT WWW.WEATHER.GOV/DETROIT.
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