891
FXUS63 KAPX 151810
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
110 PM EST SUN DEC 15 2024
KEY MESSAGES
- MIXED PRECIPITATION, INCLUDING FREEZING RAIN/FREEZING DRIZZLE,
TRANSITIONS TO MOSTLY PLAIN DRIZZLE BY THIS AFTERNOON.
- RAIN CHANCES AND WARMER TEMPERATURES MONDAY
- SNOW CHANCES AND COOLER TEMPERATURES RETURN MID WEEK
UPDATE
ISSUED AT 1126 AM EST SUN DEC 15 2024
MORNING SYNOPSIS: 13Z SURFACE ANALYSIS SHOWS A 1020MB LOW NEAR
DBQ...3MB/3H PRESSURE RISES SUGGEST THIS LOW WON'T BE AROUND MUCH
LONGER. MONSTER 1049MB HIGH OVER NEW ENGLAND (+2 TO +3 SIGMA
STANDARDIZED ANOMALY). COMPACT MID LEVEL CIRCULATION SPINNING
NORTHEAST INTO SOUTHWEST LOWER...PUSHING A SCATTERED AREA OF
PRECIPITATION ACROSS THE LOWER PENINSULA. EXPANSIVE AREA OF LOW
CEILINGS/FOG FROM WISCONSIN/ILLINOIS WESTWARD INTO THE MIDWEST.
PRECIPITATION COVERAGE AT MID MORNING HAS BEEN MOST PREVALENT ACROSS
NORTHEAST LOWER AND THE STRAITS REGION. 12Z APX SOUNDING SHOWS A
WARM NOSE ABOUT 3500FT DEEP WITH A MAX TEMPERATURE OF +2C...SO
PRECIPITATION HAS BEEN FALLING MAINLY AS LIQUID BUT ONLY THE HIGHER
TERRAIN REMAINS BELOW FREEZING AT THE SURFACE.
FORECAST UPDATE: COMPACT UPPER LOW WILL SPIN ITS WAY EAST ACROSS
SOUTHERN LOWER MICHIGAN THIS AFTERNOON AND INTO THE MID ATLANTIC
STATES BY TONIGHT. SURFACE REFLECTION LARGELY FALLS APART AS PARENT
SYSTEM OUTRUNS IT TO THE EAST...LEAVING SOUTHEASTERLY BOUNDARY LAYER
FLOW INTO NORTHERN MICHIGAN INTO TONIGHT. LOW LEVEL WARM ADVECTION
INCREASES LATER TONIGHT BUT COLUMN DRIES OUT AS WELL.
PRECIPITATION EXPECTED TO BECOME MORE DRIZZLY WITH TIME TODAY AS MID
LEVELS DRY OUT BUT LOW LEVEL MOISTURE REMAINS ENTRENCHED ALONG WITH
WEAK ISENTROPIC ASCENT/BOUNDARY LAYER FORCING (CONVERGENCE/UPSLOPE
FLOW). MOST AREAS ARE AT OR ABOVE FREEZING...AND HAVE TRIMMED AWAY
SOME OF THE ADVISORY ALONG THE LAKESHORE COUNTIES AND THROUGH THE
STRAITS. USED BELOW FREEZING ROAD TEMPERATURE PROBABILITIES TO
OUTLINE WHERE THE ADVISORY WILL REMAIN UP UNTIL ITS 18Z EXPIRATION.
ALSO ADDED MORE FOG PROBABILITIES THIS AFTERNOON AND TONIGHT BASED
ON SREF VISIBILITY PROBABILITIES LESS THAN 3 MILES.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 251 AM EST SUN DEC 15 2024
PATTERN SYNOPSIS/FORECAST: EARLY THIS MORNING, MID-LEVEL CLOSED LOW
PRESSURE SITS OVER WESTERN IL ATOP A FILLING/WEAKENING SURFACE
REFLECTION SITUATED NEAR THE IL/IA/MO BORDER. THIS SURFACE FEATURE
CONTINUES TO WASH OUT OVER THE NEXT 12-18 HOURS AS IT CROSSES THE
SOUTHERN GREAT LAKES. PRECIP ASSOCIATED WITH THIS SYSTEM HAS ALREADY
BEGUN ACROSS MUCH OF NORTHERN LOWER -- AND AS A VARIETY OF
PRECIPITATION TYPES -- SOME INITIALLY SNOW WHILE OTHERS HAVE GONE
STRAIGHT TO FREEZING RAIN. AGAIN, THIS SYSTEM IS WEAKENING UPON
APPROACH, BUT WILL CONTINUE TO SEE INCREASING MID-LEVEL ASCENT
BATTLE INITIAL DRY LOW-LEVEL AIR THE FARTHER NORTH AND EAST YOU GO
WITH PRECIP TAKING LONGEST TO ARRIVE ACROSS FAR NORTHEAST LOWER AND
THE EASTERN U.P., ESPECIALLY EASTERN MACKINAC AND CHIPPEWA COUNTIES.
A MORE SUBSTANTIAL PUSH OF WARM ADVECTION EXPECTED THIS AFTERNOON,
AND EVEN MORE SO TONIGHT WITH TODAY'S WINTRY WEATHER THREAT
DIMINISHING AREA-WIDE MIDDAY ONWARD.
FORECAST DETAILS: AS WAS ALLUDED TO ABOVE, PRECIP HAS BEGUN TO FALL
ACROSS PARTS OF THE FORECAST AREA -- LARGELY AS AN INITIAL MIX OF
SNOW AND FREEZING RAIN. GIVEN PLENTY OF LOW-LEVEL DRY AIR,
EVAPORATIONAL COOLING SHOULD CONTINUE TO SUPPORT AT LEAST A BRIEF
PERIOD OF SNOW AS PRECIP INITIALLY REACHES THE GROUND FARTHER NORTH
AND EAST. THIS COULD POSSIBLY RESULT IN A QUICK COATING ACROSS SOME
AREAS BEFORE AN INCREASINGLY WARM NOSE ALOFT IS EXPECTED TO RATHER
QUICKLY RESULT IN A TRANSITION TO FREEZING RAIN/FREEZING DRIZZLE
WITH SURFACE TEMPS IN THE UPPER 20S TO LOW 30S. PRECIP EXPECTED TO
TAKE LONGEST TO ARRIVE ACROSS THE EASTERN HALF OF CHIPPEWA/MACKINAC
COUNTIES AND FAR NORTHEAST LOWER IN PLACES LIKE ROGERS CITY AND
ALPENA -- LIKELY NOT UNTIL AFTER SUNRISE. THESE AREAS MAY ONLY HAVE
A VERY SHORT WINDOW OF POTENTIAL WINTRY PRECIP BEFORE SURFACE TEMPS
RISE ABOVE FREEZING AND THUS REMAIN OUT OF THE INHERITED WINTER
WEATHER ADVISORY.
IN THE ADVISORY AREA, THE MAIN IMPACT EXPECTED TO COME FROM FREEZING
RAIN/FREEZING DRIZZLE THIS MORNING -- ON THE ORDER OF A GLAZE TO UP
TO A TENTH OF AN INCH OR SO. SLICK TRAVEL IS ANTICIPATED,
ESPECIALLY ON UNTREATED AND SNOW-PACKED SECONDARY ROADS. HAVE
GONE AHEAD AND ADDED WESTERN MACKINAC COUNTY INTO THIS ADVISORY,
WHICH IS THE ONE SPOT IN THE EASTERN U.P. THAT SEEMS MOST
FAVORED FOR SOME MINOR SNOW AND ICE ACCUMS.
BY EARLY AFTERNOON, SURFACE TEMPERATURES ARE EXPECTED TO HAVE
CLIMBED ABOVE FREEZING AREA-WIDE WITH ANY REMAINING PRECIP LIKELY
FALLING AS PLAIN LIGHT RAIN/DRIZZLE. GRUNGY CONDITIONS WITH PATCHY
DRIZZLE AND FOG MAY LINGER RIGHT ON THROUGH TONIGHT WITH TEMPS
ACTUALLY WARMING FOR THE SECOND HALF OF THE NIGHT GIVEN A STRONGER
PUSH OF LOW-LEVEL WARM ADVECTION.
LONG TERM /MONDAY THROUGH SATURDAY/
ISSUED AT 251 AM EST SUN DEC 15 2024
FORECAST PATTERN:
MONDAY MORNING AN UPPER TROUGH WILL CONTINUE EASTWARD ACROSS THE
NORTHERN AND CENTRAL PLAINS. DEEP GULF MOISTURE WILL SURGE UP
TOWARDS THE GREAT LAKES REGION, POSSIBLY INCREASING PWATS TO 0.5" BY
MIDDAY MONDAY AS THE WARM SECTOR SPREADS ACROSS NORTHERN MI. LIGHT
STRATIFORM RAIN CHANCES AND BREEZY WINDS WILL BE SEEN MOST OF MONDAY
AS HIGH TEMPERATURES REACH INTO THE LOW 40S ACROSS THE REGION
(POSSIBLY MID TO HIGH 40S WHERE LOCAL AFFECTS FROM BREEZY SOUTHERLY
WINDS YIELD ADDITIONAL WARMING). AT THIS TIME, DETERMINISTIC
GUIDANCE SHOWS THE UPPER TROUGH BECOMING NEGATIVELY TILTED AND MEETS
UP WITH THE MAIN MOISTURE PLUME AS ITS PASSES OVER MI - RESULTING IN
THE BEST RAINFALL TOTALS RESIDING NEAR THE LK HURON COAST AND NEAR
SAGINAW BAY. THE HIGHEST SNOW PACK RESIDES OVER EASTERN UPPER AND NW
LOWER, WHICH IS WHERE VERY LIGHT RAIN WILL LIKELY FALL (WITH
ACCUMULATIONS OF < 0.10" FORECASTED). DUE TO THE MISALIGNED OF
THESE FEATURES, RAIN ON SNOW FLOODING ISN'T A CONCERN. WITH THAT
SAID, THERE IS STILL A DECENT SPREAD IN HOW MUCH MOISTURE IS ABLE TO
REACH NORTHERN MI MONDAY (0.3" TO 1" SPREAD OF PWATS). HIGH-RES
GUIDANCE IS JUST STARTING TO COME IN FOR MONDAY, AND SHOULD HELP
NARROW DOWN THE POSSIBILITIES.
A WEAKER COLD FRONT WILL PUSH THROUGH LATER MONDAY EVENING, TURNING
WINDS WEST AND WILL ALLOW SOME LES TO BEGIN. SNOW CHANCES WILL
LINGER FOR THE TYPICAL SNOW BELTS LATE MONDAY NIGHT THROUGH TUESDAY
AFTERNOON. MORE WIDESPREAD CHANCES FOR LIGHT SNOW MOVE OVER MI LATE
TUESDAY INTO WEDNESDAY. A CANADIAN SURFACE AIRMASS WILL BUILD IN
LATER IN THE WORK WEEK AND CONTINUE SNOW FOR TYPICAL SNOW BELT AREAS
THROUGH THE END OF THE WEEK. TEMPERATURES COOL BACK DOWN NEAR THE
END OF THE WORK WEEK.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 108 PM EST SUN DEC 15 2024
ANTICIPATING AN EXTENDED PERIOD OF IFR/LIFR CONDITIONS TO SETTLE
IN THIS AFTERNOON AND CONTINUE INTO MONDAY MORNING. MINIMAL
PRECIPITATION IS EXPECTED OUTSIDE OF SOME OCCASIONAL DRIZZLE
THROUGH TONIGHT (WITH ABOVE FREEZING TEMPERATURES)...A BETTER
CHANCE OF SOME LIGHT RAIN/DRIZZLE DURING THE DAY MONDAY AS A
COLD/OCCLUDED FRONT WILL CROSS THE STATE.
APX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LHZ345-
347.
SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR LHZ346-348-
349.
SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LMZ323-
341-342-344>346.
SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LSZ322.
SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR LSZ321.
UPDATE...JPB
SHORT TERM...MJG
LONG TERM...ELD
AVIATION...JPB
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