359
FXUS63 KDTX 021553
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1153 AM EDT WED APR 2 2025
KEY MESSAGES
- A CONDITIONAL THREAT EXISTS FOR SEVERE WEATHER TODAY INTO EARLY
TONIGHT WITH DAMAGING WINDS AND FLOODING THE PRIMARY THREATS ALONG
WITH POTENTIAL FOR A TORNADO OR TWO. LARGE HAIL WILL BE A
SECONDARY THREAT. THE HIGHEST CONFIDENCE FOR SEVERE WEATHER IS FROM
LATE AFTERNOON THROUGH THIS EVENING.
- A FLOOD WATCH IS IN EFFECT FOR FAR SOUTHEASTERN MI INCLUDING METRO
DETROIT THIS EVENING THROUGH THURSDAY MORNING.
- DRY BUT WINDY CONDITIONS EXPECTED THURSDAY WITH GUSTS APPROACHING
40 MPH DURING THE DAY.
- ADDITIONAL RAIN ARRIVES ACROSS THE AREA FRIDAY NIGHT INTO SATURDAY.
UPDATE
FIRST ITEM OF BUSINESS IS THE WINTER WEATHER THAT IMPACTED THE
THUMB/TRI CITIES EARLIER THIS MORNING AND ONGOING LOCALIZED ICING.
WEBCAMS/OBS/REPORTS SUGGEST SNOW ACCUMULATIONS HAVE BEEN CONFINED TO
GRASSY SURFACES AND LIGHT ICING CONFINED TO ELEVATED SURFACES. TEMPERATURES
HOVERING AROUND THE FREEZING MARK AND ROAD TEMPERATURES SEVERAL
DEGREES ABOVE THAT SUGGEST IMPACTS ARE MINIMAL THUS THE WINTER
WEATHER ADVISORY WAS ALLOWED TO EXPIRE ON SCHEDULE AND NO ADDITIONAL
HEADLINES ARE PLANNED AT THIS TIME.
NOW THAT THE INITIAL WAVE OF PRECIPITATION HAS LARGELY PASSED
THROUGH THE REGION, FOCUS TURNS TO THE SEVERE WEATHER AND FLOODING
THREAT FOR LATER THIS AFTERNOON. FIRST, THE SEVERE THREAT, WHICH
REMAINS HIGHLY CONDITIONAL ON DESTABILIZATION PROSPECTS AND TIMING OF
THE EXISTING CONVECTIVE LINE OVER ILLINOIS. SURFACE- BASED
INSTABILITY IS ALMOST ENTIRELY DEPENDENT ON THE PACE AT WHICH THE
SURFACE WARM FRONT LIFTS NORTHWARD, WHICH HAS JUST PASSED THROUGH
LAFAYETTE, IN AND LIMA, OH (ABOUT 80 MILES SOUTH OF THE MI STATE
LINE) AND HOW "CLEAN" THE WARM SECTOR REMAINS. DESPITE A SLOW START
THIS MORNING, OBSERVATIONS HAVE GENERALLY CAUGHT UP TO THE STRENGTH
AND POSITIONING OF THE MODELED WARM SECTOR (AS OF 15Z). THIS LENDS
CONFIDENCE TO TIMING THE LOCAL ARRIVAL OF THE WARM FRONT, IN WHICH
MODELS PROJECT TO REACH THE MI-OH BORDER RIGHT AROUND 00Z/8PM EDT.
THE MAIN UNCERTAINTY RIGHT NOW IS HOW QUICKLY THE UPSTREAM
CONVECTIVE LINE MOVES INTO SE MICHIGAN. A DIFFERENCE IN 1-2 HOUR
ARRIVAL TIME WILL BE THE DIFFERENCE BETWEEN WHETHER STORMS STAY
ELEVATED OR CAN TAP INTO SURFACE-BASED INFLOW. IF STORMS DO REMAIN
ELEVATED, IT WILL BE MUCH HARDER TO REALIZE A DAMAGING WIND/TORNADO
THREAT, LEAVING HAIL AND FLOODING AS THE PRIMARY CONTENDERS FOR
SEVERE WEATHER. IF STORMS ARRIVE JUST AN HOUR OR TWO LATER THOUGH,
THIS MAY PROVIDE ENOUGH TIME FOR THE WARM FRONT TO LIFT INTO SOUTHERN
PORTIONS OF THE CWA (GENERALLY SOUTH OF I-94) AND SIGNIFICANTLY
WEAKEN/LOWER THE INVERSION. IF THIS OCCURS, STORMS COULD CAPITALIZE
ON EXCEPTIONAL LOW LEVEL SHEAR PROFILES AND THE WIND/TORNADO RISK
BECOMES MORE LIKELY. 4PM UPDATE SHOULD HAVE A BETTER HANDLE ON THESE
TRENDS. REGARDLESS OF WHETHER STORMS ARE SURFACE-BASED OR ELEVATED,
FLOODING REMAINS A CONCERN AND THE FLOOD WATCH CONTINUES.
HYDROLOGY
SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS BEGIN THIS MORNING AND
CONTINUE THROUGH LATE TONIGHT, BRINGING POTENTIAL FOR HEAVY RAINFALL.
DAYTIME RAINFALL IS NOT EXPECTED TO CAUSE WIDESPREAD FLOODING AS
AMOUNTS WILL GENERALLY HOLD UNDER 1 TO 1.5 INCHES, WITH HIGHEST
AMOUNTS ACROSS THE NORTHERN TIER COUNTIES WHERE FLASH FLOOD GUIDANCE
IS GENERALLY ABOVE 2 INCHES. A SECOND WAVE OF THUNDERSTORMS, SOME
STRONG TO SEVERE, WILL SPREAD INTO THE METRO DETROIT AREA THIS
EVENING AND OVERNIGHT AHEAD OF A COLD FRONT. CELL MOTION WILL BE
NEARLY PARALLEL TO THE COLD FRONT IN A HIGH MOISTURE ENVIRONMENT,
CONDUCIVE TO TRAINING STORMS WITH HEAVY RAINFALL. COVERAGE AHEAD OF
THE FRONT REMAINS A POINT OF UNCERTAINTY IN THE GUIDANCE, BUT A HIGH
COVERAGE SCENARIO WOULD LEAD TO RAINFALL AMOUNTS OF AT LEAST 2
INCHES WITH LOCALIZED HIGHER TOTALS. 6-HOUR FLASH FLOOD GUIDANCE IN
THE DETROIT METRO AREA IS GENERALLY BETWEEN 1.5 TO 2 INCHES,
SUPPORTING INCREASED FLASH FLOODING CONCERNS ESPECIALLY FOR THE
URBAN AREAS OF DETROIT AND RISES IN AREA RIVERS. A FLOOD WATCH IS IN
EFFECT THIS EVENING INTO TONIGHT.
PREV DISCUSSION
ISSUED AT 758 AM EDT WED APR 2 2025
AVIATION...
THE LEAD SURGE OF MOISTURE IS UNDERWAY TO START THIS TAF PERIOD.
EXPECT DETERIORATING CONDITIONS THROUGHOUT TODAY DOWN TO IFR/LIFR
CEILINGS BY THIS AFTERNOON WITH THIS STRONG MOISTURE PUSH INTO
SOUTHEAST MICHIGAN. A BRIEF PERIOD OF WINTRY MIX MAINLY NORTH OF PTK
IS STILL EXPECTED BEFORE A TRANSITION TO RAIN AND A CHANCE OF
THUNDERSTORMS ARRIVES. A PREVAILING RAIN WILL CARRY THROUGH TODAY
WITH A SECONDARY THREAT OF THUNDERSTORMS THIS AFTERNOON AND EVENING
ASSOCIATED WITH A FRONTAL PASSAGE. EXPECTING SOUTHEAST WINDS TO BE
GUSTING TO NEAR 30 KNOTS GIVEN THE INCREASED GRADIENT FLOW
THROUGHOUT TODAY. SHOWERS AND THUNDERSTORMS CLEAR OUT LATE THIS
EVENING WITH PERIOD OF LOW CLOUDS LINGERING UNTIL CONDITIONS
GRADUALLY IMPROVE EARLY TOMORROW MORNING.
FOR DTW... VFR QUICKLY BELOW 5000 FT AND INTO MVFR THIS MORNING AS
RAIN SHOWERS INCREASE FROM THE WEST. THE CHANCE FOR THUNDERSTORMS
EXISTS THIS MORNING WITH THE LEAD SURGE OF MOISTURE WITH A SECONDARY
CHANCE FOR THUNDERSTORMS POSING A GREATER SEVERE THREAT THIS
AFTERNOON AND EVENING. CEILINGS HANG AROUND IFR/LIFR THROUGHOUT MUCH
OF THE AFTERNOON.
DTW THRESHOLD PROBABILITIES...
* MODERATE FOR CEILING 5000 FT OR LESS THIS MORNING. HIGH THIS
AFTERNOON.
* MODERATE FOR THUNDERSTORMS MID TO LATE MORNING AND AGAIN IN THE
AFTERNOON/EVENING.
PREV DISCUSSION...
ISSUED AT 414 AM EDT WED APR 2 2025
DISCUSSION...
A COMPACT 140 KT UPPER JET STREAK SPREADS FROM THE SOUTHERN PLAINS
INTO THE GREAT LAKES BY THIS EVENING, RIDING WITHIN THE BASE OF A
POTENT UPPER WAVE TAKING ON A NEGATIVE TILT. THIS SYSTEM PLACES SE
MI WITHIN A REGION OF STRONG SYNOPTIC ASCENT AND ROBUST MOISTURE
ADVECTION TODAY AND TONIGHT. THE SURFACE LOW LIFTS ACROSS IA THIS
MORNING BEFORE REACHING WESTERN LAKE SUPERIOR LATE THIS EVENING -
ITS WARM FRONT RACING NORTHWARD ACROSS THE OHIO VALLEY AND
APPROACHING THE SOUTHERN MI BORDER LATE THIS AFTERNOON. OUR
PLACEMENT NORTH OF THE FRONT MOST OF THE DAY MAINTAINS A GUSTY
SOUTHEAST WIND REACHING 30 TO 35 MPH. STRONG ISENTROPIC ASCENT AND
MERIDIONAL TRANSPORT OF GULF MOISTURE UP THE ELEVATED WARM FRONTAL
SLOPE IS RESPONSIBLE FOR A DEVELOPING COMPLEX OF THUNDERSTORMS AND
SHOWERY WINTRY MIX WORKING IN FROM NORTHERN IL THIS MORNING. A BRIEF
LULL IN PRECIPITATION IS POSSIBLE AFTER THIS MORNING CONVECTION
WORKS THROUGH, THEN A SECOND ROUND IS LIKELY BY LATE IN THE DAY
THROUGH TONIGHT AS THE COLD FRONT APPROACHES FROM THE WEST. MULTIPLE
HAZARDS ARE ASSOCIATED WITH THIS POTENT SPRING SYSTEM AND WILL BE
DISCUSSED SEPARATELY BELOW.
WINTER: A WINTER WEATHER ADVISORY IS IN EFFECT ACROSS THE TRI-CITIES
AND NORTHERN THUMB THIS MORNING AS THESE AREAS SIT A FEW DEGREES
BELOW FREEZING WHILE THE PRECIP WORKS IN. A FULLY SUB-FREEZING
PROFILE EARLY MAINTAINS SNOW PRODUCTION OVER THE NEXT FEW HOURS
BEFORE THE WARM NOSE PUNCHES INTO THE 850-700MB LAYER TO TRANSITION
PRECIP TO A SLEET AND FREEZING RAIN CHARACTER BEFORE THE SURFACE
LAYER SLOWLY REBOUNDS ABOVE FREEZING THROUGH MID-MORNING. MINOR
SNOW/SLEET ACCUMULATIONS OF UP TO 2 INCHES AND A GLAZE OF UP TO
0.10" OF ICE IS FORECAST, WHICH MAY BRING SLICK TRAVEL CONDITIONS
FOR THE MORNING COMMUTE. WINTRY PRECIP APPEARS POSSIBLE AS FAR SOUTH
AS THE I-96 CORRIDOR WITH IMPACTS TO TRAVEL LESS LIKELY GIVEN A
SHORTER RESIDENCE TIME PERIOD EARLY THIS MORNING.
SEVERE: SPC HAS HIGHLIGHTED THE AREA IN AN ENHANCED RISK (3 OUT OF
5) FOR SEVERE WEATHER, DRIVEN MAINLY BY POTENTIAL FOR DAMAGING,
POTENTIALLY SIGNIFICANT (>70 MPH), WIND ALONG WITH A HIGHER THAN
NORMAL THREAT FOR TORNADOES. THE PRIMARY WINDOW FOR SEVERE WEATHER
IS EXPECTED TO BE LATER IN THE DAY WHEN SURFACE-BASED INSTABILITY
CREEPS IN FROM THE SOUTH - THIS WILL BE DISCUSSED BELOW. DO WANT TO
BRING ATTENTION TO THE ELEVATED CONVECTION CURRENTLY DEVELOPING OVER
CENTRAL AND NORTHERN IL. WHILE SE MI CURRENTLY SITS NORTH OF THE
WARM FRONT WITH A STRONG INVERSION ALOFT HOLDING STATIC STABILITY IN
PLACE, MULTIPLE RUNS OF CAMS HAVE SHOWN EVIDENCE OF SURFACE-BASED
PRESSURE PERTURBATIONS AS THE CONVECTION ROLLS THROUGH THIS MORNING,
POSSIBLY INDICATIVE OF MESOSCALE GRAVITY WAVE PRODUCTION BEING
CAPTURED BY THE MODELS. RECENT RESEARCH SUGGESTS THESE FEATURES ARE
ONE AVENUE FOR DAMAGING WIND GUSTS TO BREAK THROUGH THE STABLE LAYER
AND REACH THE SURFACE, EVEN IN AN OTHERWISE ELEVATED CONVECTION
SCENARIO LIKE WE EXPECT THIS MORNING. THESE STORMS WILL BEAR
MONITORING THROUGH THE MORNING FOR POTENTIALLY STRONG TO SEVERE
GUSTS.
SEVERE THREAT LATER TODAY REMAINS CONDITIONAL ON WHETHER ENOUGH
INSTABILITY CAN WORK IN FROM THE SOUTH IN BETWEEN THUNDERSTORM
COMPLEXES. VERY STRONG WIND SHEAR WILL BE PRESENT WITH 0-6KM BULK
SHEAR PROGGED AT 50 KNOTS, SUPPORTING ORGANIZED STORM DEVELOPMENT.
SHEAR ORIENTATION PARALLEL TO THE INBOUND FRONT/AXIS OF FORCING
MAKES LINEAR CONVECTION THE LIKELY STORM MODE WITH POTENTIAL FOR
EMBEDDED SUPERCELL STRUCTURES. AT THIS STAGE THE BULK OF GUIDANCE
DOES SHOW SURFACE FLOW FLIPPING TO SOUTHWEST IN THE SOUTH BY 21Z,
ALLOWING UP TO 500-1000 J/KG OF MLCAPE TO SEEP NORTHWARD TO ABOUT
THE I-96 CORRIDOR - ROUGHLY IN LINE WITH THE CURRENT ENHANCED RISK
AREA. THIS REMAINS THE FAVORED AREA FOR SEVERE TO SIGNIFICANT WINDS
AS WELL AS THE HIGHEST POTENTIAL FOR ANY TORNADOES. THE LLJ
APPROACHING 70 KT WILL SWEEP OUT VERY LONG 0-3KM HODOGRAPHS WITH
LARGE AMOUNTS OF STREAMWISE HELICITY /SRH OF 250-400 M2/S2/
AVAILABLE FOR ANY STORMS THAT DEVIATE MORE TOWARD AN ENE STORM
MOTION. THE SEVERE THREAT WINDOW APPEARS TO BE CENTERED BETWEEN 5PM
AND MIDNIGHT.
FLOODING: WPC HAS HIGHLIGHTED THE AREA IN A SLIGHT RISK (2 OUT OF 4)
FOR EXCESSIVE RAINFALL, AND A FLOOD WATCH IS IN EFFECT FOR
SOUTHEASTERN PORTIONS OF THE CWA INCLUDING ALL OF METRO DETROIT, ANN
ARBOR, PORT HURON, ADRIAN, AND MONROE. SOUNDINGS INDICATE SEVERAL
FACTORS THAT WILL BE FAVORABLE FOR HEAVY RAINFALL AND HEIGHTENED
FLOODING POTENTIAL. ANOMALOUSLY HIGH DEEP-LAYER MOISTURE IN THE
COLUMN CHARACTERIZED BY PWAT OF AROUND 1.50" WILL CHALLENGE THE
DAILY/WEEKLY RECORD. THIS IS PAIRED WITH A >10 KFT WARM CLOUD LAYER
AND TALL, SKINNY CAPE PROFILE WHICH ARE BOTH SUPPORTIVE OF EFFICIENT
SMALLER DROPLET RAINFALL PROCESSES. THE SOUTHWEST LLJ WILL SUSTAIN A
TREMENDOUS FEED OF GULF MOISTURE WITH BOTH NAEFS AND ECMWF ENSEMBLE
INTEGRATED WATER VAPOR TRANSPORT EXCEEDING MODEL CLIMATOLOGY FOR
THIS TIME OF YEAR. THE DEEP LAYER SOUTHWEST FLOW PARALLEL TO THE
SLOWLY PROGRESSING COLD FRONT WILL ALSO RESULT IN WEAK CORFIDI
UPSHEAR VECTORS OF 10 KT OR LESS TONIGHT, INDICATING A FAVORABLE
COMBO OF STORM MOTION AND BACKBUILDING PROPAGATION TO PRODUCE
POSSIBLE TRAINING STORMS. THESE TYPES OF SETUPS CAN CAUSE VERY HEAVY
RAINFALL RATES AND FLASH FLOODING. THIS FORECAST UPDATE HIGHLIGHTS
WIDESPREAD STORM TOTALS OF 1.50 TO 2.00 INCHES ACROSS ALL OF
SOUTHEAST MI. LOCALLY HIGHER AMOUNTS, POSSIBLY EXCEEDING 3 INCHES,
CANNOT BE RULED OUT IF REPEATED STORMS TRAIN OVER THE SAME LOCATION.
HIGHEST CONFIDENCE FOR THIS TO OCCUR IS WITHIN THE FLOOD WATCH AREA.
THE MAIN WINDOW OF CONCERN FOR HEAVY RAINFALL AND FLOODING WILL BE
BETWEEN 8PM AND 4AM THU.
SHOWERS AND STORMS SHOULD EXIT THE AREA EARLY THURSDAY MORNING AS
THE FRONT WORKS EAST INTO ONTARIO/LAKE ERIE. BOUNDARY LAYER MIXING
WITHIN THE ENSUING COLD ADVECTION WILL TAP INTO 40-45 KT SOUTHWEST
GRADIENT FLOW PRODUCING GUSTS IN THE 30 TO 40 MPH RANGE THROUGH THE
DAYLIGHT HOURS. HIGH PRESSURE THEN BUILDS IN ACROSS THE REGION ON
FRIDAY PROMOTING MORE TRANQUIL CONDITIONS. THE UPPER JET WILL HOLD
OVER THE REGION, ITS PROXIMITY SETTING THE STAGE FOR ANOTHER ROUND
OF RAIN THAT LOOKS INCREASINGLY LIKELY FRIDAY NIGHT INTO SATURDAY.
STILL LOTS OF DETAIL TO WORK OUT WITH GOVERNING FEATURES, BUT LATEST
GUIDANCE LARGELY FAVORS A SURFACE LOW RELEASING NORTHEAST ACROSS THE
OHIO VALLEY AND BRINGING WIDESPREAD RAIN TO SE MI. AT THIS TIME
SEVERE WEATHER DOES NOT LOOK LIKELY WITH THIS SYSTEM GIVEN OUR
PLACEMENT ON ITS NORTHWEST FLANK, BUT THE ADDITIONAL RAINFALL MAY
EXACERBATE ANY POTENTIAL FLOODING IMPACTS FROM TONIGHT'S CONVECTION.
MARINE...
WINDS HAVE RAMPED UP OUT OF THE EAST/SOUTHEAST OVERNIGHT AHEAD OF
THE NEXT LOW PRESSURE SYSTEM THAT WILL LIFT THROUGH THE REGION
TONIGHT. WINDS ACROSS LAKE HURON WILL LIKELY REACH GALES THIS
EVENING SO THERE IS A GALE WARNING FOR THE WHOLE LAKE. ADDITIONALLY,
FARTHER SOUTH ACROSS LAKE ST CLAIR AND LAKE ERIE, WINDS LOOK TO HOLD
AROUND 30 KNOTS WITH BUILDING WAVE HEIGHTS LEADING TO A PERIOD OF
SMALL CRAFT ADVISORIES FOR THOSE LAKES. A WARM FRONT WILL LIFT
THROUGH THE REGION EARLY TO MIDDAY BRINGING A FIRST ROUND OF
THUNDERSTORMS. THE COLD FRONT WILL SWEEP THROUGH LATE THIS EVENING
WHICH WILL FLIP THE WINDS AROUND TO THE SOUTHWEST AND THOUGH THEY
WILL REMAIN ELEVATED, WILL TOP OUT AROUND THE MID 20 KNOT RANGE.
THERE WILL ALSO BE POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS
ACROSS THE LAKES THIS EVENING INTO THE EARLY OVERNIGHT. THE FRONT
WILL THEN STALL ACROSS THE OHIO RIVER VALLEY THROUGH THE END OF THE
WEEK AS HIGH PRESSURE BUILDS BACK OVER THE GREAT LAKES KEEPING
GUSTY WESTERLY FLOW THURSDAY AND LIGHTER NORTHERLY FLOW FRIDAY.
HYDROLOGY...
SEVERAL ROUNDS OF SHOWERS AND THUNDERSTORMS BEGIN THIS MORNING AND
CONTINUE THROUGH LATE TONIGHT, BRINGING POTENTIAL FOR HEAVY RAINFALL.
DAYTIME RAINFALL IS NOT EXPECTED TO CAUSE WIDESPREAD FLOODING AS
AMOUNTS WILL GENERALLY HOLD UNDER 1 TO 1.5 INCHES, WITH HIGHEST
AMOUNTS ACROSS THE NORTHERN TIER COUNTIES WHERE FLASH FLOOD GUIDANCE
IS GENERALLY ABOVE 2 INCHES. A SECOND WAVE OF THUNDERSTORMS, SOME
STRONG TO SEVERE, WILL SPREAD INTO THE METRO DETROIT AREA THIS
EVENING AND OVERNIGHT AHEAD OF A COLD FRONT. CELL MOTION WILL BE
NEARLY PARALLEL TO THE COLD FRONT IN A HIGH MOISTURE ENVIRONMENT,
CONDUCIVE TO TRAINING STORMS WITH HEAVY RAINFALL. COVERAGE AHEAD OF
THE FRONT REMAINS A POINT OF UNCERTAINTY IN THE GUIDANCE, BUT A HIGH
COVERAGE SCENARIO WOULD LEAD TO RAINFALL AMOUNTS OF AT LEAST 2
INCHES WITH LOCALIZED HIGHER TOTALS. 6-HOUR FLASH FLOOD GUIDANCE IN
THE DETROIT METRO AREA IS GENERALLY BETWEEN 1.5 TO 2 INCHES,
SUPPORTING INCREASED FLASH FLOODING CONCERNS, ESPECIALLY FOR THE
URBAN AREAS OF DETROIT, AND RISES IN AREA RIVERS. A FLOOD WATCH IS
IN EFFECT THIS EVENING INTO TONIGHT.
DTX WATCHES/WARNINGS/ADVISORIES
MI...FLOOD WATCH FROM 8 PM EDT THIS EVENING THROUGH THURSDAY MORNING FOR
MIZ063-069-070-075-076-082-083.
LAKE HURON...GALE WARNING UNTIL 10 PM EDT THIS EVENING FOR LHZ361>363-421-422-
441>443-462>464.
LAKE ST CLAIR...SMALL CRAFT ADVISORY UNTIL 4 AM EDT THURSDAY FOR LCZ460.
MICHIGAN WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT THURSDAY FOR LEZ444.
UPDATE.......MV
AVIATION.....AA
DISCUSSION...TF
MARINE.......DRK
HYDROLOGY....MV/TF
YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE
AT WWW.WEATHER.GOV/DETROIT.
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