980
FXUS63 KDTX 220453
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
1153 PM EST FRI FEB 21 2025
KEY MESSAGES
- TEMPERATURES WARM THIS WEEKEND WITH HIGHS SATURDAY AND SUNDAY IN
THE LOW TO MID 30S, AND AT OR ABOVE 40 DEGREES MONDAY THROUGH
WEDNESDAY.
- DRY WEATHER THIS WEEKEND WITH BETTER PRECIPITATION CHANCES EARLY
NEXT WEEK.
AVIATION
LATE EVENING OBSERVATIONS INDICATE NOCTURNAL ACTIVATION OF LAKE
MICHIGAN MVFR STRATOCU THAT IS ON A TRAJECTORY TO GRAZE MBS DURING
THE LATE NIGHT. VFR HOLDS ACROSS THE REMAINDER OF SE MI AS THE AREA
SITS BETWEEN OHIO VALLEY HIGH PRESSURE AND CANADIAN LOW PRESSURE.
THIS SETS UP INCREASING SW WIND AS THE PRIMARY WEATHER FACTOR WITH
STREAMLINES STILL ORIGINATING FROM MID MS/OH VALLEY HIGH PRESSURE OF
GRADUALLY MODIFYING POLAR ORIGIN. FROM THE NORTH, HIGH CLOUDS
THICKEN AND LOWER TO MID LEVELS IN THE AFTERNOON BUT REMAIN VFR
ABOVE 5000 FT. THICKENING CLOUDS ARE ACCOMPANIED BY SW WIND REACHING
GUSTS IN THE MID 20 KNOT RANGE BY MID AFTERNOON INTO SATURDAY
EVENING.
DTW THRESHOLD PROBABILITIES
* NONE.
PREV DISCUSSION
ISSUED AT 357 PM EST FRI FEB 21 2025
DISCUSSION...
A SHARP GRADIENT IN CLOUD COVER THIS MORNING HAS DECAYED ALMOST
ENTIRELY OVERHEAD, WITH MOST AREAS SEEING FULL SUNSHINE AT ISSUANCE.
HIGH PRESSURE DRIFTING INTO THE OHIO VALLEY TRENDS WIND DIRECTION TO
THE SOUTHWEST THIS EVENING WHICH, IN THE NEAR-TERM, WILL DIRECT A
SECOND WAVE OF DECAYING LAKE CLOUD ACROSS THE AREA. DESPITE A CHILLY
START TO SATURDAY MORNING (LOWS IN THE TEENS), ALL EYES ARE ON THE
WARMING TREND ANTICIPATED THIS WEEKEND INTO EARLY NEXT WEEK.
THE PATTERN SHIFT IS ALREADY UNDERWAY ALOFT WHERE THE STRONG ARCTIC
RIDGE HAS FLATTENED SUBSTANTIALLY OVER THE PAST 24 HOURS. THE LESS
AMPLIFIED PATTERN DRIVES OUT THE EXISTING ARCTIC AIRMASS TO BRING
TEMPERATURES CLOSER TO NORMAL THIS WEEKEND, WITH DAYTIME HIGHS
SATURDAY AND SUNDAY IN THE LOW TO MID 30S. THAT SAID, THE THERMAL
RIDGE WILL BE SLOW TO VACATE ENTIRELY LEAVING IN ITS WAKE A
BAROCLINIC ZONE THAT DIRECTS NUMEROUS SHORTWAVES OF VARYING
WAVELENGTH/AMPLITUDE RIGHT INTO THE GREAT LAKES THROUGH THE WEEKEND.
MID/HIGH CLOUD IS LIKELY WITH THESE SYSTEMS TO SOME DEGREE, BUT
SOUNDINGS ARE FAR TOO DRY (10-15 KFT DRY LAYERS) AND FORCING TOO
WEAK TO SUPPORT PRECIPITATION SURVIVING TO THE GROUND.
MORE ORGANIZED SYNOPTIC FORCING POTENTIAL ARRIVES AS EARLY AS SUNDAY
NIGHT WITH THE PHASING OF A WEAK PV ANOMALY AND ~95 KNOT JET STREAK,
ALTHOUGH MOISTURE DEPTH WILL STILL STRUGGLE WITH LACK OF GULF
MOISTURE INFLUENCE. EVEN OVER THE TRI CITIES/THUMB WHERE LAKE
MOISTURE COULD CLIP, SOUNDINGS STILL PROJECT AT LEAST A 2-3 KFT DRY
LAYER THAT SHOULD EVAPORATE ANY SURVIVING HYDROMETEORS. A TREND
TOWARD STRONGER PV ANOMALIES AND PHASING OF UPPER/LOW LEVEL DYNAMICS
THEN DEVELOPS THROUGH EARLY NEXT WEEK, CULMINATING INTO THE BEST
CHANCE OF MEASURABLE PRECIPITATION BEING TUESDAY AS A PV ANOMALY AND
COLD FRONT PHASE ACROSS THE GREAT LAKES. AT THIS POINT, MODELS
PROJECT PWAT VALUES BETWEEN 0.5-0.75" WHICH WOULD SUPPORT JUST A
LIGHT QPF EVENT WITH TEMPERATURES SUPPORTING P-TYPE OF RAIN. THE
REST OF THE MID-WEEK PERIOD WILL BE DICTATED BY HOW FAR SOUTH THE
FRONT SETTLES AND ANY CONSTRUCTIVE/DESTRUCTIVE INTERFERENCE BETWEEN
ADDITIONAL WAVES THAT ARE EXPECTED TO DEVELOP.
MARINE...
A DIFFUSE PRESSURE GRADIENT WITHIN A RIDGE OF HIGH PRESSURE
MAINTAINS LIGHT WINDS THROUGH THE REST OF THE AFTERNOON. AS THIS
RIDGE EXITS SOUTHEAST TONIGHT, WINDS WILL REORGANIZE OUT OF THE
SOUTHWEST AS THE GRADIENT STRENGTHENS AGAIN. A 30 TO 40 KT WSW LOW-
LEVEL JET WILL SPREAD OVER THE CENTRAL GREAT LAKES TONIGHT,
BOLSTERING GUSTY SW TO WSW WINDS THROUGH SATURDAY. THE BULK OF THE
JET CORE MOMENTUM IS EXPECTED TO REMAIN ABOVE A STABLE LAYER, BUT
ENOUGH MIXING WITHIN THE NEAR-SURFACE LAYER OFFERS A WINDOW FOR 25
TO 30 KNOT GUSTS TO DEVELOP SATURDAY - STRONGEST ACROSS NORTHERN
LAKE HURON, SAGINAW BAY, AND DOWNWIND INTO CENTRAL LAKE HURON. A
PERIOD OF 35 KT GALES CANNOT BE RULED OUT FOR CENTRAL PORTIONS OF
THE LAKE IN THE AFTERNOON, BUT WITH ONLY 30 TO 40% PROBABILITY FOR
ABOUT 3 TO 4 HOURS, WILL HOLD OFF ON GALE HEADLINES. THE JET PASSES
EAST BY LATE SATURDAY EVENING, CAUSING WIND TO SUBSIDE. MODERATE SW
WIND PERSISTS THROUGH SUNDAY WITH A MILDER AIR MASS SETTLING INTO
THE REGION. MONDAY PRESENTS THE NEXT WINDOW FOR AN UPTICK IN SW TO S
WINDS AS A CLIPPER SYSTEM TRACKS INTO THE NORTHERN GREAT LAKES. AN
ACTIVE BUT MILDER PATTERN IS IN STORE FOR EARLY NEXT WEEK WITH
SEVERAL ADDITIONAL LOW PRESSURE SYSTEMS LIKELY TO AFFECT THE AREA.
LOW CONFIDENCE EXISTS ON TIMING AND STRENGTH OF THESE SYSTEMS.
DTX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
LAKE HURON...NONE.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....BT
DISCUSSION...MV
MARINE.......TF
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