313
FXUS63 KDTX 202353
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
753 PM EDT SUN APR 20 2025
KEY MESSAGES
- SHOWERS BECOME LIKELY TONIGHT INTO EARLY MONDAY. A SLIGHT CHANCE
OF THUNDERSTORMS DURING THIS TIME.
- TURNING WINDY MONDAY AFTERNOON AND EVENING WITH SOUTHWEST GUSTS IN
EXCESS OF 35 MPH.
AVIATION
HIGH PRESSURE INFLUENCE WANES TONIGHT AS A LOW PRESSURE SYSTEM LIFTS
NORTHEAST ACROSS THE UPPER MIDWEST. ELEVATED PORTION OF THE SYSTEM'S
WARM FRONT IS ALREADY MAKING INROADS ACROSS SOUTHERN LOWER MICHIGAN
PER WARMING OF THE 1-3 KM AGL LAYER, BASED ON ACARS SOUNDINGS. THIS
PROMOTES COLUMN MOISTENING AMIDST THE SHIFT TO SOUTHERLY LOW-LEVEL
FLOW. EXPECT CURRENT PRECIPITATION ARC TO HOLD OVER CENTRAL LOWER
THROUGH THE NEXT 6-8 HOURS GIVEN CLOSER PROXIMITY TO THE UPPER-LEVEL
WAVE AND STRONGER VAPOR TRANSPORT PROCESSES. STILL, CANNOT RULE OUT
SOME VIRGA EARLY TONIGHT, ESPECIALLY OVER MBS. MODELS SUGGEST
SUFFICIENT MOISTENING SHOULD BE ACHIEVED SHORTLY AFTER 06Z WITH A
LINE OF SHOWERS LIFTING IN FROM THE SOUTHWEST. LAPSE-RATES ALOFT
AREN'T PARTICULARLY IMPRESSIVE, BUT A FEW SHOWERS COULD GENERATE
OCCASIONAL LIGHTNING AS A PLUME OF WEAK ELEVATED INSTABILITY ALSO
MOVES IN. CEILINGS ARE EXPECTED TO DROP INTO MVFR CATEGORY WITH
LINGERING MORNING SHOWERS AS SURFACE WINDS LAG, EVENTUALLY VEERING
SOUTH-SOUTHWESTERLY. MIXED-LAYER ACTIVATES LATE MONDAY MORNING WITH
THE INITIAL COLD FRONT WHICH LEADS TO STRONG GUSTY WINDS DURING THE
DAY AND WINDS VEERING TOWARD THE WEST. POTENTIAL EXISTS FOR SOME
ADDITIONAL SHOWER ACTIVITY AND GUSTS IN EXCESS OF 30 KNOTS.
FOR DTW...CANNOT RULE OUT A THUNDERSTORM OR TWO EARLY MONDAY
MORNING, THEN SHOWERS LINGER THROUGH THE REST OF THE MORNING HOURS.
WIND GUSTS SPIKE DURING THE AFTERNOON.
DTW THRESHOLD PROBABILITIES
* LOW FOR CEILING AT OR BELOW 5000 FEET EARLY TONIGHT, THEN MEDIUM
MONDAY MORNING.
* LOW FOR THUNDERSTORMS EARLY MONDAY MORNING.
PREV DISCUSSION
ISSUED AT 338 PM EDT SUN APR 20 2025
DISCUSSION...
UPPER-LEVEL CONFLUENT FLOW THROUGH THE MORNING HAS REINFORCED HIGH
PRESSURE THIS AFTERNOON WITH A 1032MB PRESSURE CENTER NOW LOCATED
OVER THE GEORGIAN BAY. THIS HAS AND WILL CONTINUE TO SUPPORT DRY
WEATHER WITH MOSTLY SUNNY CONDITIONS, WHICH HAVE ALLOWED TEMPERATURES
TO CAP OUT IN THE LOW TO MID-50S DESPITE THE LINGERING THERMAL
TROUGH. A COMPACT UPPER-LEVEL WAVE HAS HELPED ORGANIZE A WEAK LOW
PRESSURE SYSTEM OVER THE PANHANDLE OF TEXAS WHICH WILL THEN PIVOT AND
TRACK INTO THE CENTRAL PLAINS AND MIDWEST, JUST WEST OF LAKE
MICHIGAN. UPPER-LEVEL TROUGH WILL TURN NEGATIVELY TILTED OWING TO THE
MATURING SYSTEM WITH THE LOW PRESSURE SYSTEM BECOMING A LITTLE MORE
ORGANIZED, REACHING AN OCCLUDED STATE AS IT TRAVERSES INTO THE GREAT
LAKES TOMORROW.
IMPACTS FOR SE MI WILL INITIALLY BE THE BOOST IN THETA-E ADVECTION
WHICH WILL MITIGATE THE FULL RANGE OF NOCTURNAL COOLING OVERNIGHT,
WITH LOWS HOLDING IN THE MID 40S. A WARM FRONT WILL INITIATE RAIN
CHANCES THROUGHOUT THE MORNING HOURS WITH SOME ADDITIONAL SUPPORT
ALOFT ALONG THE NOSE OF AN UPPER-LEVEL JET. WHILE NOT CONFORMING TO
THE TRADITIONAL JET STREAK MODEL, ROSSBY NUMBER ANALYSIS HIGHLIGHTS
A BOOST IN AGEOSTROPHIC CIRCULATION THROUGH THE RIGHT EXIT REGION.
CANNOT RULE OUT SOME ISOLATED THUNDERSTORM PRODUCTION GIVEN MODEST
ELEVATED INSTABILITY WITH MID-LEVEL LAPSE RATES AOA 6 C/KM. PASSAGE
OF THE LOW INTO THE NORTHERN GREAT LAKES TOMORROW WILL SWEEP A COLD
FRONT OVER THE STATE IN THE LATE MORNING AND AFTERNOON HOURS.
PENDING THE TIMING OF THE FRONT, SOME MODEST SURFACE BASED CAPE MAY
INTERSECT THE FRONTAL PASSAGE, BRINGING A WINDOW FOR ISOLATED
THUNDERSTORMS LEADING INTO THE AFTERNOON BEFORE A DRY SLOT WORKS IN.
STEEPER LLLR DURING DAYLIGHT HOURS AND WILL THE PASSAGE OF THE COLD
FRONT WILL AID IN SHALLOW MIXING WHICH WILL BE ENOUGH TO TAP INTO
STRONGER WINDS ALOFT UP TO 45 KNOTS. ACCOUNTING FOR MOMENTUM
TRANSFER, WIND GUSTS AROUND 40 MPH WILL BE LIKELY THROUGH THE DAY,
WITH SOME ISOLATED GUSTS TO OR JUST ABOVE 45 MPH POSSIBLE. LACK OF
FOLIAGE ON TREES LIMITS CONCERNS FOR ISL/SCT POWER OUTAGES.
PRECIPITATION CHANCES WILL REMAIN ON THE LOWER SIDE THROUGH THE
MIDWEEK PERIOD DUE TO THE LOWER PREDICTABILITY UNDER ZONAL FLOW
ALOFT. ENSEMBLES ARE HIGHLIGHTING THE POSSIBILITY FOR ADDITIONAL
CHANCES ON WEDNESDAY ALONG AN STATIONARY FRONTAL SLOPE, BUT THIS
WILL BE PENDING THE FINAL LOCATION OF THE FRONT AND DEGREE OF
OVERRUNNING, WHICH AT THIS TIME LOOKS WEAK. OF HIGHER CONFIDENCE,
NORMAL TO ABOVE NORMAL TEMPERATURES ARE LIKELY THROUGH THE MID TO
LATE WEEK PERIOD AGAIN DUE TO A MORE STAGNANT UPPER-AIR PATTERN.
MARINE...
1034 MB SURFACE HIGH PRESSURE MIGRATES FURTHER INTO QUEBEC THIS
EVENING, LEAVING IN ITS WAKE LIGHT EASTERLY FLOW ACROSS ALL LOCAL
WATERS. LOW PRESSURE NOW OVER THE SOUTHERN PLAINS WILL LIFT ALONG AN
EXISTING FRONTAL ZONE TO THE STRAITS BY MONDAY EVENING, DRAWING AN
OCCLUDED FRONT THROUGH THE REGION MONDAY AFTERNOON. AHEAD OF THIS
FRONT, STRONG MOISTURE ADVECTION OCCURS IN THE MIDST OF A 50 KNOT
LOW LEVEL JET WHICH ALSO ELEVATES WINDS/WAVES TO AT LEAST SMALL
CRAFT ADVISORY THRESHOLDS. WIDESPREAD SHOWERS AND EMBEDDED RUMBLES
OF THUNDER WILL BE POSSIBLE LATE TONIGHT-MONDAY MORNING AS A RESULT.
STABILITY IN THE WARM FRONTAL ZONE OF THIS SYSTEM SHOULD KEEP GUSTS
AOB 30 KNOTS THROUGH MONDAY AFTERNOON, BUT ONCE THE FRONT COMES
THROUGH AND THE BOUNDARY LAYER MIXES, THERE IS POTENTIAL FOR GUSTS
TO INCREASE MONDAY EVENING/OVERNIGHT. MOMENTUM TRANSFER FIELDS FLIRT
WITH 35-40 KNOTS FOR BOTH SAGINAW BAY (MONDAY EVENING) AND NORTHERN
LAKE HURON (LATE MONDAY NIGHT), WHERE VEERING WIND PROFILES BRIEFLY
ALIGN WITH THEIR RESPECTIVE MAJOR AXES. THAT SAID, LACK OF MODEL
CONSENSUS AND SHORT DURATION/MARGINAL MAGNITUDE OF THIS SETUP DO NOT
AFFORD THE CONFIDENCE TO GO WITH A GALE WARNING WITH THIS ISSUANCE.
WILL CONTINUE TO MONITOR FORECAST TRENDS. OTHERWISE, CONDITIONS
IMPROVE ON TUESDAY AS HIGH PRESSURE RETURNS TO THE GREAT LAKES.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...SMALL CRAFT ADVISORY FROM 8 AM MONDAY TO 10 AM EDT TUESDAY FOR
LHZ421-422.
SMALL CRAFT ADVISORY FROM 4 AM MONDAY TO 10 AM EDT TUESDAY FOR
LHZ441>443.
LAKE ST CLAIR...SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 4 AM EDT TUESDAY FOR
LCZ460.
MICHIGAN WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 4 AM EDT TUESDAY FOR
LEZ444.
AVIATION.....KGK
DISCUSSION...AM
MARINE.......MV
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