910
FXUS63 KDTX 151052
AFDDTX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI
552 AM EST SUN DEC 15 2024
KEY MESSAGES
- POTENTIAL FOR SLICK CONDITIONS ACROSS THE SAGINAW VALLEY THIS
MORNING AS FREEZING RAIN TRACKS THRU THE AREA. A WINTER WEATHER
ADVISORY REMAINS IN EFFECT.
- WARMER CONDITIONS TODAY AS AREAS OF LIGHT RAIN PERSIST.
- SEASONABLY WARM TEMPERATURES BREAK THE 50 DEGREE MARK (SOUTH OF I-
69) MONDAY WITH MORE RAIN, THEN READINGS DECLINE THROUGHOUT THE
WORKWEEK.
AVIATION
FREEZING RAIN IS ONGOING AT MBS, FNT, AND PTK AS TEMPERATURES HOVER
AROUND THE FREEZING MARK. A SURGE OF WARM AIR IS EXPECTED BETWEEN 7
AM AND 9 AM EST THIS MORNING, WHICH WILL TRANSITION ANY FREEZING
PRECIPITATION TO ALL RAIN. STEADY PRECIPITATION WILL HELP LOWER
CIGS/VSBYS OVER THE NEXT COUPLE OF HOURS TOWARD IFR. THIS IS IN
SPITE OF DRY, LIGHT EASTERLY FLOW THAT HAS HELPED DELAY SIGNIFICANT
LOWERING THUS FAR. RAIN TAPERS OFF THIS AFTERNOON AS AN UPPER LOW
TRACKS ACROSS SE MICHIGAN, BUT THE LOW CLOUD DECK STICKS AROUND AND
ACTUALLY LOWERS IN RESPONSE TO DRY AIR MOVING IN ALOFT AND LOWERING
INVERSION HEIGHTS. THIS PROCESS HAS BEEN OBSERVED UPSTREAM OVER
IA/MN/WI WHERE THERE IS A LARGE SWATH OF 200 FT CEILINGS AND LESS
THAN 1/2 SM VSBY. BASED ON BOTH THESE OBSERVATIONAL TRENDS AND
FORECAST MODEL GUIDANCE, DID DECIDE TO BE AGGRESSIVE AND GO WITH
LIFR AFTER 23Z TONIGHT. LIGHT WINDS SHIFT TO A MORE SOUTHERLY
DIRECTION MONDAY MORNING, WHILE DRIER AIR BEGINS TO MIX INTO THE LOW
LEVELS A RAISE CEILINGS BACK TO 500 FEET OR GREATER.
FOR DTW...PRECIPITATION IS FALLING AS ALL RAIN CURRENTLY WITH AN AIR
TEMPERATURE OF 32 DEGREES. RAIN WILL BE STEADY THROUGH THE MORNING
AND TAPER OFF EARLY AFTERNOON. THERE IS MEDIUM CONFIDENCE THAT
CEILINGS/VSBYS WILL FALL INTO VLIFR RESTRICTIONS LATE THIS EVENING.
DTW THRESHOLD PROBABILITIES...
* HIGH FOR CEILINGS AT OR BELOW 5000 FEET THROUGH MONDAY MORNING.
* HIGH IN PRECIPITATION BEING ALL RAIN TODAY.
* MEDIUM FOR CIGS/VSBY TO FALL BELOW 200 FT AND/OR 1/2 SM
PREV DISCUSSION
ISSUED AT 351 AM EST SUN DEC 15 2024
DISCUSSION...
EARLY MORNING SURFACE ANALYSIS SHOWS LOW PRESSURE TRACKING ACROSS
WESTERN ILLINOIS, WITH A WARM FRONTAL ZONE STRETCHING EASTWARD INTO
OHIO VALLEY. CORRIDOR OF MOIST ISENTROPIC ASCENT EMANATING NORTH OF
THESE FEATURES MAINTAINED WITHIN THE BROADER REGION OF ELEVATED WARM
AIR ADVECTION, RESULTING IN AN EXPANSIVE PRECIPITATION SHIELD NOW
MAKING INROADS THROUGHOUT SOUTHEAST MICHIGAN. DRY EASTERLY FLOW
EFFECTIVELY RELENTING FROM SOUTH TO NORTH AS SUFFICIENT MAGNITUDE TO
THETA-E ADVECTION WORKS TO SATURATE THE PROFILE, WHILE A WARMING
COLUMN ENSURES THIS ARRIVES IN LIQUID FORM. PERUSAL OF LOCAL
OBSERVATIONS SUGGEST ADEQUATE NEAR SURFACE WARMING NOW ALLOWING
TEMPERATURES FOR MOST LOCATIONS OUTSIDE OF THE SAGINAW VALLEY TO
RESIDE SAFELY ABOVE FREEZING, MEANING SIMPLY JUST RAIN GOING
FORWARD. WINDOW REMAINS ACROSS THE SAGINAW VALLEY FOR FREEZING RAIN
TO GENERATE SOME LIGHT ICE ACCUMULATION OVER THE NEXT SEVERAL HOURS.
WINTER WEATHER ADVISORY REMAINS IN EFFECT THROUGH 12Z FOR THIS
CORRIDOR.
MOIST AND MILDER CONDITIONS WILL EXIST THROUGHOUT SUNDAY AS THE
TRAILING CLOSED LOW MEANDERS ACROSS THE REGION ATOP AN INCREASINGLY
DIFFUSE WARM FRONT/TROUGH AXIS. THIS PATTERN MAINTAINS UNSETTLED
CONDITIONS AS FOCUSED AREAS OF DCVA WITHIN THE UNDERLYING MID LEVEL
CYCLONIC FLOW CONTRIBUTES ADDITIONAL POCKETS OF LIGHT RAIN/DRIZZLE
DURING THE DAYLIGHT HOURS. THE MODERATING THERMAL PROFILE WILL
SUPPORT HIGHS NEAR 40 DEGREES. A QUICK TRANSITION TOWARD BUILDING
UPPER HEIGHTS TONIGHT WITH THE BACKGROUND OF SOUTH TO SOUTHEAST LOW
LEVEL WILL MINIMIZE ANY NOCTURNAL COOLING POTENTIAL, LEAVING LOWS
WITHIN SEVERAL DEGREES OF LATE DAY READINGS.
WARMING TREND SOLIDIFIED HEADING INTO MONDAY AS FLOW VEERS TO
SOUTHWESTERLY AND INCREASES DEPTH IMMEDIATELY DOWNSTREAM OF THE NEXT
INBOUND UPPER WAVE. ANOTHER QUICK SHOT OF MEANINGFUL MOIST
ISENTROPIC ASCENT WITHIN THE STRENGTHENING PATTERN OF WARM AIR
ADVECTION RESULTS IN A HIGH PROBABILITY, LIGHT RAINFALL EVENT DURING
THE DAYLIGHT PERIOD. COLLECTIVE ENSEMBLE SOLUTION SPACE ONBOARD WITH
THIS OUTCOME. TEMPERATURES PEAK THIS PERIOD NEAR 50 DEGREES. MODEST
COLD AIR ADVECTION EMERGES MONDAY EVENING INTO THE OVERNIGHT HOURS
AS HEIGHT FALLS COMMENCE WITH THE UPPER TROUGH PASSAGE. THE
ADVECTIVE PROCESS LACKS STRENGTH GIVEN PACIFIC ORIGIN, BUT MAY
CONTRIBUTE TO SOME GUSTINESS OF WEST-SOUTHWEST WIND OVERNIGHT WITHIN
THE POST-FRONTAL ENVIRONMENT AS PROJECTED WINDS OF 30-35 KNOTS EXIST
AT THE TOP OF THE MIXED LAYER.
A MILDER RESIDENT THERMAL PROFILE WILL HOLD INTO THE MIDWEEK PERIOD,
AS THE LARGE SCALE PATTERN REMAINS GOVERNED BY LOWER AMPLITUDE FLOW
OF POLAR ORIGIN. DRY AND GUSTY CONDITIONS PERSIST INTO TUESDAY
WITHIN A FIRM WESTERLY GRADIENT. A BRIEF PERIOD OF MEANINGFUL FORCED
ASCENT WILL ATTEMPT TO MATERIALIZE WEDNESDAY WITHIN THE NORTH FLANK
OF LOW PRESSURE TRACKING ACROSS THE OHIO/TENNESSEE VALLEY AND ALONG
A COLD FRONT ATTENDANT TO ADDITIONAL INBOUND HEIGHT FALLS FROM THE
NORTH. AN ILL-DEFINED SETUP AT THIS STAGE OWING TO EXPECTED
DEVIATION WITHIN THE MODEL SOLUTION SPACE ON PLACEMENT AND
INTERACTION OF KEY FEATURES. FORECAST WILL CONTINUE TO OFFER A MORE
GENERAL OUTLOOK FOR THE POSSIBILITY OF LIGHT RAIN AND SNOW GIVEN
MARGINAL MELTING LAYER DEPTH FOCUSED DURING THE DAYLIGHT PERIOD
WHERE TEMPS PEAK IN THE MID/UPPER 30S.
MARINE...
SOUTHEAST WINDS OF 15 TO 25 KNOTS CONTINUE OVER LAKE HURON TODAY,
ALLOWING 4+ WAVES TO IMPACT THE NEARSHORE ZONES. WINDS ATTEMPTING TO
BECOME MORE DUE SOUTHERLY INTO SUNDAY NIGHT. WARMER AIR WILL
GRADUALLY WORK INTO THE REGION ALLOWING FOR PRECIPITATION TO FALL
FALL AS RAIN TODAY AS WEAKENING LOW PRESSURE TRACKS IN FROM THE
MIDWEST. THIS LOW AND ANY COLD AIR FIZZLE OUT IN FAVOR OF THE
STRONGER/MORE AMPLIFIED UPPER LEVEL TROUGH OVER THE NORTHERN PLAINS
SUNDAY NIGHT.
RESUMED MODERATE SOUTHERLY FLOW CAN BE EXPECTED WITH ADDITIONAL RAIN
BY MONDAY. COLD FRONT, ATTACHED TO LOW PRESSURE TRACKING THROUGH
ONTARIO AND NEAR JAMES BAY, WILL SWING THROUGH THE CENTRAL GREAT
LAKES EARLY MONDAY EVENING. TIGHT PRESSURE GRADIENT WITH 850 MB
TEMPS LOWERING TO AROUND -8 C LOOKS SUPPORTIVE OF WIND GUSTS IN
THE 30 TO 35 KNOT RANGE OVER CENTRAL AND NORTHERN LAKE HURON, LATE
MONDAY NIGHT INTO EARLY TUESDAY MORNING. HOWEVER, GUSTS TO GALES
APPEAR TO BE BRIEF, AS THE PRESSURE GRADIENT QUICKLY RELAXES DURING
THE DAY ON TUESDAY. THUS, NOT PLANNING ON GALE WATCH AT THIS TIME.
AN EVEN STRONGER COLD FRONT LOOKS TO BE MOVING THROUGH ON WEDNESDAY,
AND NORTHERLY WINDS LATE WEDNESDAY THROUGH THURSDAY MORNING WILL
LIKELY REACH INTO THE 20 TO 30 KNOT RANGE, BUT ULTIMATELY INFLUENCED
BY THE STRENGTH AND POSITION OF LOW PRESSURE TRACKING THROUGH/NEAR
THE SOUTHERN OHIO VALLEY. A RIDGE OF HIGH PRESSURE QUICKLY FOLLOWS,
ALLOWING FOR A PERIOD OF LIGHT WINDS TO END THE WORK WEEK.
DTX WATCHES/WARNINGS/ADVISORIES
MI...WINTER WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR MIZ047-048-
053.
LAKE HURON...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR LHZ421.
SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LHZ441-442.
SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR LHZ443.
LAKE ST CLAIR...NONE.
MICHIGAN WATERS OF LAKE ERIE...NONE.
AVIATION.....MV
DISCUSSION...MR
MARINE.......SF
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