325
FXUS63 KAPX 190734 CCA
AFDAPX
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE GAYLORD MI
234 AM EST THU DEC 19 2024
KEY MESSAGES
- WIDESPREAD SNOW THIS AFTERNOON THROUGH FRIDAY MORNING. HIGHEST
SNOW TOTALS EXPECTED ACROSS PARTS OF NORTHEAST LOWER MICHIGAN.
- SOME LINGERING LAKE EFFECT SNOW ACTIVITY ACROSS PORTIONS OF
THE SNOWBELTS FRIDAY. LITTLE TO MINIMAL IMPACTS EXPECTED.
- ANOTHER BRIEF VERY COLD SPELL SATURDAY INTO SATURDAY NIGHT,
WITH HIGHS IN THE TEENS SATURDAY, AND POTENTIAL FOR SUB-ZERO
LOWS SATURDAY NIGHT.
- TRENDING WARMER NEXT WEEK WITH POTENTIAL FOR SOME MIXED PRECIPITATION
THAT EVENTUALLY YIELDS RAIN AS WELL-ABOVE-NORMAL TEMPERATURES
RETURN.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 203 AM EST THU DEC 19 2024
PATTERN SYNOPSIS/FORECAST: WEAK MID-LEVEL RIDGING SITS ATOP
NORTHERN MICHIGAN AT THIS EARLY HOUR. FOCUS THROUGH THE SHORT
TERM REVOLVES AROUND UPSTREAM MID-LEVEL SHORTWAVE TROUGHING AND
ATTENDANT ~1013MB LOW PRESSURE CURRENTLY OVER NORTHERN PLAINS
THAT'S EXPECTED TO TREK SOUTHEAST ACROSS THE LOWER GREAT LAKES
LATE TODAY THROUGH TONIGHT. THIS SYSTEM IS EXPECTED TO BRING
WIDESPREAD LIGHT TO MODERATE SNOW TO NORTHERN MICHIGAN WITH SOME
LOCALLY HEAVIER ENHANCEMENT ACROSS NORTHEAST LOWER MICHIGAN.
FORECAST DETAILS: SOME LIGHT LAKE INDUCED SNOW SHOWER ACTIVITY/
FLURRIES POSSIBLE THROUGH THE EARLY MORNING ACROSS PARTS OF EASTERN
UPPER AND NORTHWEST LOWER, BUT WITH LITTLE FANFARE EXPECTED.
ATTENTION TURNS TO THIS AFTERNOON THROUGH TONIGHT AS SNOW IS
EXPECTED TO ARRIVE FROM WEST TO EAST -- LARGELY SNOWING AREA-WIDE BY
00-02Z THIS EVENING.
SNOW CONTINUES LIGHT TO MODERATELY THROUGH THE OVERNIGHT HOURS
ACROSS THE VAST MAJORITY OF NORTHERN MICHIGAN. SNOW AMOUNTS EXPECTED
TO VARY FROM 1-3" ACROSS EASTERN UPPER AND FROM 1.5-3.5" ACROSS THE
VAST MAJORITY OF NORTHERN LOWER. THE EXCEPTION TO THIS LIES ACROSS
NORTHEAST LOWER WHERE SOUTHEAST FLOW LAKE ENHANCEMENT IS EXPECTED TO
BRING LOCALLY HEAVIER SNOW THIS EVENING THROUGH TONIGHT WITH POCKETS
OF HIGHER TOTALS RANGING FROM 4-8". WHILE THERE REMAINS LOTS OF
UNCERTAINTY WITH RESPECT TO WHERE EXACTLY THAT EMBEDDED HEAVIER
BANDING MATERIALIZES (INFLUENCED HEAVILY BY EVEN A 10-20 DEGREE WIND
CHANGE), CURRENT CONFIDENCE FAVORS A SOLUTION THAT BRINGS THOSE
HIGHER END TOTALS INTO PARTS OF ALCONA AND ALPENA COUNTIES. WILL GO
AHEAD AND ISSUE A HANDFUL OF WINTER WEATHER ADVISORIES FOCUSED NEAR
THE LAKE HURON COAST WITH AT LEAST SOME POTENTIAL FOR ADVISORIES TO
BE EXPANDED BY THE DAY SHIFT TO INCLUDE A LARGER PORTION OF NORTHERN
MICHIGAN. A FEW OF THESE ADVISED COUNTIES MAY ALSO NEED TO BE
UPGRADED TO A WINTER STORM WARNING AS CONFIDENCE IN HIGHER END
TOTALS INCREASED OVER THE NEXT 12-18 HOURS.
LONG TERM /FRIDAY THROUGH WEDNESDAY/
ISSUED AT 203 AM EST THU DEC 19 2024
PATTERN SYNOPSIS / FORECAST:
LONGWAVE TROUGHING WILL BE IN THE PROCESS OF GETTING FORCED EASTWARD
BY A RIDGING REGIME AMPLIFYING QUITE CONSIDERABLY OVER THE PLAINS
INTO THE WEEKEND. EMBEDDED SHORTWAVE (THE CLIPPER SYSTEM SET TO PASS
THROUGH TONIGHT) WILL BE ON THE MOVE EASTWARD, AND IN ITS WAKE, LAKE
EFFECT INSTABILITY WILL CONTRIBUTE TO SOME CONTINUED LAKE EFFECT
SNOW (ALBEIT, NOT ANYWHERE NEAR AS ROBUST AS WHAT WE SAW OVER
THANKSGIVING OR LAST WEEK). EVENTUALLY, THIS REGIME IS MUTED BY A
1040MB SURFACE HIGH PROGGED TO PASS RIGHT OVER US LATER SATURDAY
INTO SUNDAY, WHICH SHOULD DELIVER THE CORE OF AN ARCTIC AIRMASS TO
THE REGION. MEANWHILE, THAT AMPLIFYING RIDGING WILL EVENTUALLY MAKE
ITS WAY INTO THE REGION... DRIVEN BY A HEINOUS BELCH OF PACIFIC AIR
VIA A ROBUST JET OVER THAT AFOREMENTIONED OCEAN... WHICH SHOULD
RETURN WELL-ABOVE NORMAL TEMPERATURES TO THE REGION NEXT WEEK. MAY
NEED TO WATCH FOR AN EMBEDDED SHORTWAVE EARLY NEXT WEEK WHICH COULD
BRING ABOUT POTENTIAL FOR A MIXY PRECIP OCCURRENCE, BUT ALL IN ALL,
PATTERN RECOGNITION SAYS THIS IS PROBABLY ANOTHER ONE OF THOSE
PERIODS WHERE WE REMAIN ABOVE FREEZING FOR AN EXTENDED PERIOD OF
TIME BOTH DAY AND NIGHT (UNFORTUNATELY PROBABLY COINCIDING WITH THE
CHRISTMAS HOLIDAY).
PRIMARY FORECAST CONCERNS:
FRIDAY THRU EARLY SATURDAY LAKE EFFECT: SYNOPTIC SNOWS ASSOCIATED
WITH THE CLIPPER SYSTEM WILL BE ON A GRADUAL DOWNWARD TREND THROUGH
THE MORNING HOURS ON FRIDAY, WITH POTENTIAL FOR SOME CONTINUED LAKE
ENHANCEMENT ACROSS NE LOWER AS NORTHEAST WINDS REMAIN DOMINANT IN
THE MORNING HOURS. ONCE THE TROUGH AXIS ASSOCIATED WITH THE CLIPPER
FINALLY CLEARS, WE SHOULD BE LOOKING AT A MORE DEFINED N TO NNW WIND
REGIME, WHICH SHOULD PLACE THOSE RESPECTIVE SNOWBELTS IN THE ZONE TO
RECEIVE AN ADDITIONAL FEW INCHES OF SNOW... SO PROBABLY WHITEFISH
POINT, US 131 AND POINTS WEST, AND PRESQUE ISLE / ALPENA COUNTIES
FROM FRIDAY EVENING THROUGH SATURDAY AFTERNOON. NOT UNIMPACTFUL, BUT
CERTAINLY NOT HIGHER END IMPACTS ANTICIPATED AT THIS JUNCTURE.
SATURDAY THRU SUNDAY COLD: WITH SURFACE HIGH PRESSURE BUILDING
DIRECTLY OVERHEAD SATURDAY NIGHT, EXPECTING WINDS TO DECOUPLE AND
SKIES TO CLEAR QUITE VIGOROUSLY WITH STRONG SUBSIDENCE OVERHEAD.
ANTICIPATION IS THAT THE COMBINATION OF THESE FACTORS LIKELY LEADS
TO ANOTHER INSTANCE OF TEMPERATURES DROPPING LIKE A TON OF BRICKS
EARLY SATURDAY EVENING. CONSIDERING DAYTIME HIGHS ON SATURDAY WILL
BE IN THE LOW TEENS, PATTERN RECOGNITION SAYS THIS WILL PROBABLY BE
ANOTHER SUB-ZERO AIR TEMPERATURE NIGHT ACROSS MUCH OF THE REGION
(SAVE FOR THE IMMEDIATE LAKESHORES). WOULDN'T BE OVERLY SURPRISING
TO SEE THOSE INTERNAL ICEBOX LOCALES (GRAYLING, ATLANTA, TROUT LAKE,
ETC.) MAKE A RUN AT -10 AGAIN. TEMPERATURES REBOUND SOME INTO SUNDAY
AS THE NOSE OF RETURN FLOW BUILDS, WITH HIGHS IN THE 20S, BUT WITH
MINIMAL CLOUD COVER, EXPECTING ANOTHER NIGHT IN THE SINGLE DIGITS
AND TEENS SUNDAY NIGHT.
NEXT WEEK: ONSLAUGHT OF MILDER AIR WILL BEGIN SPILLING INTO THE
REGION AS THAT PACIFIC BORNE BELCH OF WARMER AIR MAKES ITS WAY
ACROSS THE CONUS. INITIAL SHORTWAVE MON - MON NIGHT (LIKELY A WAA
DRIVEN WAVE) MAY BRING THE CHANCE FOR SOME MIXED PRECIPITATION (ALL
P-TYPES ON THE TABLE) BEFORE WE SETTLE INTO A STAGNANT BUT MILDER
AIRMASS THAT FEATURES TEMPERATURES AND (MORE IMPORTANTLY) DEWPOINTS
ABOVE FREEZING BOTH DURING THE DAY AND NIGHT. THIS WILL BE EXTREMELY
DETRIMENTAL TO SNOWPACK ACROSS THE REGION, AND COULD NOT COME AT A
MORE UNFORTUNATE TIME CONSIDERING THE CHRISTMAS HOLIDAY IS THIS
UPCOMING WEDNESDAY.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1149 PM EST WED DEC 18 2024
JUST A FEW LIGHT LINGERING SNOW SHOWERS EARLY THIS MORNING.
OTHERWISE, DIMINISHING WINDS AND MOSTLY CLOUDY SKIES WITH HIGH
END MVFR/LOW END VFR CIGS. A CLIPPER SYSTEM WILL THEN SPREAD
SNOW INTO THE REGION FROM SOUTHWEST TO NORTHEAST LATE THIS
AFTERNOON INTO THIS EVENING (PERHAPS REMAINING SOUTH OF KCIU).
CIGS WILL FALL BACK TO MVFR. VSBYS IN SNOW ARE EXPECTED TO FALL
TO BETWEEN MVFR AND IFR. WINDS WILL BE JUST A TAD GUSTY OUT OF
THE EAST SOUTHEAST LATE TODAY INTO THIS EVENING.
APX WATCHES/WARNINGS/ADVISORIES
MI...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 1 PM EST
FRIDAY FOR MIZ018-024-030-036-041-042.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST EARLY THIS MORNING FOR
LHZ345>348.
SMALL CRAFT ADVISORY UNTIL 4 AM EST EARLY THIS MORNING FOR
LSZ321.
SHORT TERM...MJG
LONG TERM...HAD
AVIATION...AJS
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