834
FXUS63 KAPX 200503
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1203 AM EST FRI DEC 20 2024
KEY MESSAGES
- WIDESPREAD LIGHT SNOW THIS EVENING INTO FRIDAY MORNING.
AMOUNTS OF 1-2" ANTICIPATED FOR MOST ALONG AND WEST OF I-75.
AMOUNTS OF 2-3" EXPECTED ALONG THE M-55 CORRIDOR. HIGHEST
TOTALS OF 4-7" WITH LOCALIZED 8"+ POSSIBLE FOR PARTS OF ALPENA
AND ALCONA COUNTIES.
- LINGERING SNOW SHOWERS CONTINUE THIS SATURDAY FOLLOWED BY VERY
COLD TEMPERATURE'S THIS WEEKEND.
- ADDITIONAL SNOW CHANCES EARLY NEXT WEEK BEFORE TURNING MORE
MILD FOR CHRISTMAS AND BEYOND.
UPDATE
ISSUED AT 1024 PM EST THU DEC 19 2024
ALBERTA CLIPPER IS CENTERED ACROSS NORTHERN ILLINOIS AS OF LATE
EVENING. APX AND SURROUNDING RADARS SHOW MAINLY LIGHT SNOW
COVERING MUCH OF NORTHERN LOWER WITH LITTLE SNOW REACHING INTO
EASTERN UPPER. TWO AREAS OF ENHANCEMENT OFF OF LAKE HURON
HAVE RECENTLY DEVELOPED, THE FIRST ONE OVER CENTRAL ALCONA
COUNTY AND THE SECOND ONE OVER NORTHERN ALPENA COUNTY. HI-
RESOLUTION GUIDANCE CONTINUES TO PEG THESE AREAS WITH LOCALLY
HEAVIER SNOW AT TIMES BUT WITH WINDS GRADUALLY BACKING FROM
EAST SOUTHEAST TO NORTHEAST OVERNIGHT THESE AREAS SHOULD
GRADUALLY CHANGE THEIR FOCUS AS THE NIGHT GOES ON. CURRENT
WINTER WEATHER ADVISORIES STILL APPEAR TO BE ON TRACK WITH
LOCALLY UP TO AROUND 6 INCHES OF SNOW POSSIBLE IN THE ADVISORY
AREAS. A GENERAL 1 TO PERHAPS 2 INCHES EXPECTED ACROSS THE
REMAINDER OF NORTHERN LOWER WITH LITTLE TO NO ACCUMULATION
EXPECTED ACROSS EASTERN UPPER.
SHORT TERM /THROUGH FRIDAY/
ISSUED AT 240 PM EST THU DEC 19 2024
PATTERN SYNOPSIS:
INCREASINGLY AMPLIFIED LONGWAVE TROUGHING WILL CONTINUE TO DIG
ACROSS THE GREAT LAKES AND MISSISSIPPI VALLEY TODAY INTO FRIDAY,
WITH MULTIPLE EMBEDDED SUBTLE SHORTWAVES ROTATING THROUGH DURING
THAT TIME. THE ASSOCIATED WEAK SURFACE CYCLONE WILL TRACK ACROSS
NORTHERN IOWA, SOUTHERN WISCONSIN, AND NORTHERN ILLINOIS INTO
TONIGHT BEFORE WORKING ACROSS THE OHIO VALLEY INTO FRIDAY,
EVENTUALLY MERGING WITH A SECOND CYCLONE OFF THE ATLANTIC COAST.
FORECAST DETAILS:
WIDESPREAD SNOW INTO FRIDAY MORNING -- SNOW WILL BEGIN TO SPREAD
FROM SW TO NE ACROSS NORTHERN LOWER MICHIGAN THIS EVENING AND
TONIGHT AS THE AFOREMENTIONED SYSTEM TRACKS TO OUR SOUTH. AS STATED
IN THE KEY MESSAGES, 1-2" ARE ANTICIPATED FOR MOST AREAS OF NORTHERN
LOWER ALONG AND WEST OF I-75. SLIGHTLY HIGHER TOTALS OF 2-3" ARE
EXPECTED ALONG THE M-55 CORRIDOR. THE PRIMARY FOCUS THIS EVENING
WILL BE ACROSS NORTHEAST LOWER AND FAR SOUTHEAST UPPER MICHIGAN.
LAKE ENHANCED BANDING ASSOCIATED WITH LOW-LEVEL CONVERGENCE VISIBLE
ON SATELLITE IMAGERY EARLIER TODAY IS CURRENTLY BRINGING MORE
FOCUSED SNOWFALL TO MACKINAC ISLAND AND EASTERN PORTIONS OF MACKINAC
COUNTY. CURRENT CONFIDENCE IS THAT THIS ENHANCED BANDING WILL SET UP
ACROSS PARTS OF ALPENA AND ALCONA COUNTIES LATER THIS EVENING INTO
FRIDAY MORNING. A FAVORABLE ENVIRONMENT WITH DEEP SATURATION WILL
SUPPORT SNOWFALL TOTALS MAINLY IN THE 4-7" RANGE ACROSS THESE
COUNTIES. LOCALLY HIGHER AMOUNTS OF 8" OR MORE WILL BE POSSIBLE WITH
THIS BAND, ESPECIALLY IF IT SITS OVER ONE LOCATION FOR MULTIPLE
HOURS AS 1" PER HOUR OR GREATER SNOWFALL RATES ARE POSSIBLE. THIS
BAND IS EXPECTED TO EVENTUALLY DROP SOUTH FRIDAY MORNING, BRINGING
THESE HIGHER SNOWFALL RATES AND QUICK ACCUMULATIONS TO IOSCO AND
ARENAC COUNTIES FOR A BRIEF TIME. WHILE THE ABOVE AMOUNTS APPROACH
WARNING CRITERIA, RELATIVELY HIGH UNCERTAINTY AT THIS TIMEFRAME FOR
AMOUNTS IN EXCESS OF 7" LEADS TO HOLDING OFF ON UPGRADING EXISTING
ADVISORIES AT THIS TIME. REGARDLESS, HAZARDOUS TRAVEL CONDITIONS ARE
EXPECTED ALONG THE LAKE HURON SHORELINE THROUGH FRIDAY MORNING.
LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/
ISSUED AT 240 PM EST THU DEC 19 2024
PATTERN SYNOPSIS/FORECAST:
CURRENT LONGWAVE TROUGHING OVER THE MAJORITY OF NORTH AMERICA
CONTINUES TO ADVECT COLD AIR FROM THE NORTH INTO THE GREAT LAKES
REGION THIS WEEKEND. AN EMBEDDED DISTURBANCE WILL WORK ITS WAY FROM
THE PACIFIC TO THE MIDWEST RETURNING SOME LIGHT WET-SNOW SHOWERS AT
THE BEGINNING OF NEXT WEEK BEFORE STRONG MIDLEVEL UPSTREAM FLOW
RETURNS A MORE MILD AIRMASS TO THE NORTHWOODS JUST IN TIME FOR THE
HOLIDAY SEASON.
PRIMARY FORECAST CONCERNS/KEY MESSAGES:
-LINGERING SNOW SHOWERS CONTINUE THIS SATURDAY FOLLOWED BY VERY COLD
TEMPERATURE'S THIS WEEKEND: THE MAJORITY OF SNOWFALL ASSOCIATED WITH
THE CLIPPER HAS ENDED BY THE START OF THE LONG TERM. BACKING WINDS
WILL HAVE A LIGHT NNW FLOW FRIDAY NIGHT AND SATURDAY COMBINED WITH A
STRONG ENOUGH THERMAL GRADIENT OVER THE GREAT LAKES TO CONTINUE
LIGHT LES SHOWERS INTO SATURDAY. ACCUMULATION'S WILL REMAIN LOW AND
LOCALIZED WITH SNOWFALL TOTALS OF AROUND 2 INCHES NEAR THE GRAND
TRAVERSE BAY REGION AND LESSER FOR THE TYPICAL SNOWBELTS. MOST
IMPACTFUL WEATHER THIS WEEKEND WILL BE THE COLD NORTHERLY AIR
ADVECTING INTO THE CWA BEGINNING FRIDAY NIGHT THROUGH SUNDAY. THE
COLDEST NIGHT WILL BE SATURDAY NIGHT ACROSS INTERIOR EASTERN UPPER
AND NORTHERN LOWER AS NORTHEASTERN FLOW WILL PUSH TEMPERATURES BELOW
0. DAYTIME HIGHS WILL REMAIN IN THE TEENS AND LOW 20S BEFORE WARM
AIR ADVECTION RETURNS HIGHS ABOVE FREEZING NEXT WEEK.
-ADDITIONAL SNOW CHANCES EARLY NEXT WEEK BEFORE TURNING MORE MILD
FOR CHRISTMAS AND BEYOND: AFTER A COLD AND QUIET DAY SUNDAY,
MIDLEVEL HEIGHTS BEGIN TO RISE THIS MONDAY RETURNING A WARMER AIR
MASS TO THE NORTHWOODS. A SMALL HEIGHT DISTURBANCE WILL GENERATE
SOME LIGHT-WET SNOW SHOWERS THIS TUESDAY. ONLY A COUPLE INCHES OF
SNOW ARE EXPECTED AT THIS TIME DUE TO SUCH LOW SNOW RATIOS ALONG
WITH THE POSSIBILITY OF SOME RAIN MIXING INTO A COUPLE LOCALIZED
AREAS OF THE CWA (ESPECIALLY FOR AREAS OF NORTHERN LOWER NEAR THE
COASTLINES). TEMPERATURES CONTINUE TO RISE THROUGH THE REMAINDER OF
THE LONG TERM AS HIGHS WILL REACH THE UPPER 30S TO EVEN LOW 40S
AFTER THE HOLIDAY SEASON LIKELY IMPACTING NORTHERN MICHIGANS
SNOWPACK DURING SUCH A ECONOMICALLY BUSY TIME OF THE WINTER SEASON.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1158 PM EST THU DEC 19 2024
THE ALBERTA CLIPPER SYSTEM HAS SPREAD MAINLY LIGHT SNOW ACROSS
NORTHERN LOWER BUT THE SNOW IS NOT REACHING INTO EASTERN UPPER.
THERE ARE POCKETS OF STEADIER SNOW INTERMIXED WITH THE LIGHT
SNOW, ESPECIALLY AT APN. LAKE ENHANCED MODERATE SNOW IS POSSIBLE
THIS MORNING, ESPECIALLY AT APN. CIGS AND VSBYS ARE GENERALLY
MVFR BUT THEY COULD STILL LOWER TO IFR AT TIMES. SNOWFALL RATES
OF UP TO AN INCH PER HOUR ARE POSSIBLE AT APN WITH LOWER RATES
EXPECTED ELSEWHERE. WINDS WILL BE LIGHT EASTERLY THROUGH THIS
MORNING THEN SHIFT INTO THE NORTHWEST AND BECOME A BIT GUSTY
THIS AFTERNOON INTO FRIDAY NIGHT, ALONG WITH A FEW LAKE EFFECT
SNOW SHOWERS AROUND.
APX WATCHES/WARNINGS/ADVISORIES
MI...WINTER WEATHER ADVISORY UNTIL 1 PM EST FRIDAY FOR MIZ018-024-
030-036-041-042.
MARINE...NONE.
UPDATE...AJS
SHORT TERM...DJC
LONG TERM...SJC
AVIATION...AJS
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