399
FXUS63 KAPX 200452
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1152 PM EST SUN JAN 19 2025
KEY MESSAGES
- GETTING COLDER YET WITH MORE LAKE EFFECT SNOWS
- COLD TEMPERATURES AND WIND CHILLS THROUGH WEDNESDAY MORNING.
- LAKE EFFECT SNOW THROUGH AT LEAST TUESDAY NIGHT.
- WATCHING WIDESPREAD/ SYNOPTIC SNOW POTENTIAL FOR THE LATTER HALF
OF THE WEEK.
UPDATE
ISSUED AT 1004 PM EST SUN JAN 19 2025
SYNOPSIS: PATTERN PERSISTENCE IS THE NAME OF THE GAME AS THE AIR
MASS GETS PROGRESSIVELY COLDER ACROSS THE UPPER LAKES...FIGHTING
LAKE AGGREGATE HEATING WHICH HAS DISTORTED THE PRESSURE PATTERN TO
THE TUNE OF A SHARP NORTHWEST-SOUTHEAST SURFACE TROUGH EXTENDING
FROM WESTERN LAKE SUPERIOR...ACROSS EASTERN UPPER AND NORTHERN LAKE
HURON. 00Z APX SOUNDING HAS THE INVERSION AROUND 725MB/-32C...AND A
COLDER CBL IS IMPACTING SNOWFLAKE GROWTH (SMALLER FLAKES WHICH ARE
GREAT AT REDUCING VISIBILITY ESPECIALLY DURING THE DAY BUT AREN'T AS
EFFICIENT ACCUMULATING...WHICH IS A COMMON EVOLUTION WHEN 850MB
TEMPERATURES SINK BELOW -20C). BUT WHERE THE SNOW HAS BEEN
PERSISTENT HAVE STILL BEEN GETTING UP TO 0.5IN/HR SNOWFALL RATES
(SLRS CLOSER TO 10:1). MOST PERSISTENT CONVERGENCE HAS BEEN EAST OF
GRAND TRAVERSE BAY ACROSS ANTRIM COUNTY...AS WELL AS AROUND THE WEST
SIDE OF WHITEFISH BAY IN CHIPPEWA COUNTY. BAND HAS ALSO BEEN
LURKING OFF OF PRESQUE ISLE COUNTY THROUGHOUT THE DAY ALONG THE LAKE
AGGREGATE TROUGH AXIS...A FEW VORTICES HAVE BEEN PROPAGATING ALONG
THIS AXIS WITH A PROMINENT CIRCULATION MOVING INTO SOUTHWEST
ONTARIO. 02Z MESOANALYSIS SUGGESTS A MESOVORTEX PROPAGATING
SOUTHWARD EAST OF THE I-75 CORRIDOR WITH WINDS HAVE VEERED
NORTH/NORTHEAST AT ACB/BFA/GLR/PLN WITH FEATURE BETWEEN GOV/APN.
BROADLY CYCLONIC FLOW ALOFT WITH A SHORT WAVE TROUGH MOVING ACROSS
SOUTHERN LOWER MICHIGAN WITH SOME SYNOPTIC SNOWFALL PUSHING ACROSS
THE LOWER LAKES/MID ATLANTIC.
FORECAST UPDATE: NOT MUCH CHANGES OVERNIGHT AND INTO THE DAY MONDAY.
NORTHWEST-SOUTHEAST ORIENTED LAKE AGGREGATE TROUGH PERSISTING ACROSS
EASTERN UPPER/NORTHERN LAKE HURON INTO MONDAY MORNING...WHILE COLD
ADVECTION CONTINUES AS THE NEAR RECORD WARMTH OF THE LAKES HOLDS THE
COLDEST AIR AT BAY BUT 850MB TEMPERATURES DROPPING TO OR BELOW -25C
BY MONDAY MORNING.
WILL BE FOCUSING ON THE ABOVE MENTIONED AREAS FOR SNOW POTENTIAL
OVERNIGHT INTO MONDAY. FIRST DOWNWIND OF LAKE MICHIGAN: NO BIG
CHANGES TO THE THERMODYNAMICS OVERNIGHT OTHER THAN THE PROFILE
GETTING COLDER AND LIKELY SHIFTING SNOWFLAKE SIZE SMALLER. AREAS
THAT HAVE SEEN THE MOST PERSISTENT SNOWFALL TODAY WILL REMAIN UNDER
THE GUN TONIGHT...AND WITH WINDS BACKING A BIT MORE WESTERLY LATE
TONIGHT MAY ALSO SEE SOME OF THE BETTER ACTIVITY SHIFT TOWARD LITTLE
TRAVERSE BAY (SOUTHERN EMMET/SOUTHERN CHEBOYGAN COUNTIES) MONDAY
MORNING. GIVEN THAT ANTRIM COUNTY HAS LIKELY ALREADY PICKED UP 4-6
INCHES SINCE THIS MORNING AND WITH THE POTENTIAL FOR SIMILAR AMOUNTS
OVERNIGHT...PLAN TO UPGRADE THE ADVISORY TO A WINTER STORM WARNING
WITH NEW ACCUMULATIONS THROUGH TOMORROW AFTERNOON OF 4 TO 8 INCHES.
WILL ALSO ADD KALKASKA COUNTY TO THE ADVISORY AS HEAVIER SNOW HAS
BEEN NUDGING INTO THE NORTHERN PART OF THE COUNTY.
DOWNWIND OF LAKE SUPERIOR: SNOW SHOWERS HAVE BEEN CONFINED ALONG AND
NORTH OF THE M-28 CORRIDOR ACROSS CHIPPEWA COUNTY SO FAR THIS
EVENING. INVERSION HEIGHTS OVER EASTERN LAKE SUPERIOR CLOSER TO
650MB WITH THE LONGER FETCH. THE QUESTION OVERNIGHT IS SNOW BAND
EVOLUTION WITH AN EXPECTATION SIMILAR TO LAST NIGHT WITH EASTERLY
DRAINAGE FLOW EVENTUALLY PUSHING SNOWFALL WEST OF THE SAULT.
CONVECTIVE MORPHOLOGY MAY EVENTUALLY SPIN UP INTO A MESOVORTEX GIVEN
THE INSTABILTY AND FORCING...BUT EXPECTING 3 TO 6 INCHES NORTH OF M-
28 IN WESTERN CHIPPEWA COUNTY.
NO CHANGES TO ONGOING COLD WEATHER HEADLINES.
SHORT TERM /THROUGH MONDAY/
ISSUED AT 305 PM EST SUN JAN 19 2025
PATTERN SYNOPSIS/PATTERN FORECAST:
BARELY MODIFIED SLUG OF AIR OF ARCTIC ORIGIN CONTINUES TO FILTER
ACROSS THE GREAT LAKES REGION EARLY THIS AFTERNOON...ALLOWED TO DO
SO BY DEEP LONG WAVE TROUGHING EXTENDING FROM THE NORTHERN REACHES
OF HUDSON BAY SOUTH INTO THE GULF COAST STATES. COLDEST TEMPERATURE
ANOMALIES (H8 TEMPERATURES BELOW -30C!) ACTUALLY STILL LURKING
UPSTREAM ACROSS THE PLAINS OF SOUTHERN CANADA BEHIND SOUTHEAST
DROPPING EMBEDDED SHORTWAVE TROUGH. LAKE EFFECT SNOWS CONTINUE TO
ROTATE OFF THE BIG WATERS, WITH THE MOST ORGANIZED SNOW SHOWERS
IMPACTING THE SNOW BELTS OF UPPER MICHIGAN...DRIVEN BY LAKE
AGGREGATE TROUGHING AND SIMPLE BREADTH OF LAKE SUPERIOR OPEN WATER.
SNOW SHOWERS TRYING TO GET A BIT MORE ORGANIZED OFF NORTHERN LAKE
MICHIGAN, BUT LACK OF ANY TRUE LAKE SUPERIOR CONNECTION AND LOSS OF
IN-CLOUD DENDRITIC GROWTH LAYER CONTINUES TO SIGNIFICANTLY
THROTTLING BACK ON SNOW RATES INTO NORTHWEST LOWER MICHIGAN. STILL,
TRAVEL IMPACTS ARE NOTED AS THAT TALCUM-POWDER TYPE SNOW IS NO DOUBT
PRODUCING BRIEF PERIODS OF SIGNIFICANTLY REDUCED VISIBILITIES IN THE
MORE INTENSE SHOWERS.
REINFORCING SHOT OF ARCTIC AIR SET TO ARRIVE TONIGHT AND MONDAY
BEHIND SHORTWAVE TROUGHING THAT ROTATES THROUGH THE REGION THIS
EVENING. MAIN CORE OF ARCTIC AIR EXPECTED TO DIVE INTO THE NORTHERN
PLAINS TONIGHT, MODIFYING JUST A BIT AS IT SWINGS THROUGH THE REGION
MONDAY NIGHT AND TUESDAY.
PRIMARY FORECAST CONCERNS:
TEMPERATURE TRENDS AND LAKE SNOW EVOLUTION THROUGH MONDAY.
DETAILS:
COLD AIR WILL ONLY INTENSIFY WITH TIME TONIGHT AND MONDAY AS THAT
REINFORCING SHOT OF ARCTIC AIR ARRIVES. LAKE MODIFICATION WILL BE
SIGNIFICANT (COMES WITH A COST OF COURSE...LAKE SNOWS), HELPING KEEP
TEMPERATURES ON EITHER SIDE OF ZERO BY A FEW DEGREES ACROSS NORTHERN
LOWER MICHIGAN TONIGHT. LOOKING AT ANOTHER DRAINAGE FLOW EVENT OFF
THE PLATEAU NORTH OF THE SOO TONIGHT, LIKELY CLEARING SKIES ACROSS A
GOOD PORTION OF THE EAST HALF OF EASTERN UPPER MICHIGAN...HELPING
DRIVE TEMPERATURES SEVERAL DEGREES COLDER IN THIS REGION. THIS
MORNINGS LOWS WERE SIGNIFICANTLY COLDER NEAR THE ST. MARY'S RIVER
THAN ANY STATISTICAL GUIDANCE SUGGESTED. WILL USE THIS RECENT
HISTORY...DROPPING TEMPERATURES AT LEAST A FEW DEGREES COLDER THAN
EVEN THE COLDEST GUIDANCE. EXPECTING LOWS TO MAKE A RUN INTO THE
NEGATIVE TEENS ALONG AND NEAR THE ST. MARY'S RIVER BY SUNRISE
MONDAY. WINDS WILL BE LIGHT, BUT STILL ENOUGH TO PUSH WIND CHILL
READINGS TO NEAR CRITICAL LEVELS OF -20F. ONLY MINOR TEMPERATURE
RECOVERY EXPECTED MONDAY, WITH HIGHS LARGELY REMAINING IN THE SINGLE
DIGITS (PERHAPS EVEN STRUGGLING TO REACH ZERO NEAR THE ST. MARY'S
RIVER). WINDS BECOME INCREASINGLY GUSTY AS WELL LATER TONIGHT AND
MONDAY FOR AREAS SOUTH OF THE BIG BRIDGE. THIS WILL DROP WIND CHILLS
TO PERHAPS THE TEENS BELOW ZERO...ESPECIALLY DURING THE MORNING
HOURS.
LAKE SNOWS WILL OF COURSE CONTINUE TO TARGET OUR TRADITIONAL SNOW BELT
LOCATIONS. ACCUMULATION RATES WILL BE SIGNIFICANTLY HINDERED BY A
NON-EXISTENT DENDRITIC GROWTH LAYER. LAKE AGGREGATE
TROUGHING/POTENTIAL LAKE-INDUCED MESO-LOW DRIVEN LOW LEVEL
CONVERGENCE WILL LIKELY COMPENSATE SOME ACROSS NORTHWEST CHIPPEWA
COUNTY. EXPECTING SEVERAL MORE INCHES OF SNOW UP NEAR WHITEFISH
POINT AND PARADISE THROUGH MONDAY. DO EXPECT BANDING TO CONTINUE TO
BECOME MORE ORGANIZED ACROSS NORTHWEST LOWER MICHIGAN. AGAIN, NO
LAKE SUPERIOR CONNECTION AND DGZ WILL THROTTLE BACK SOME ON SNOWFALL
RATES, BUT SIMPLE PERSISTENCE WILL RESULT IN AT LEAST A FEW INCHES
OF SNOW UNDER THOSE MOST PERSISTENT BANDS. TALCUM POWDER CONSISTENCY
OF THE SNOW WILL RESULT IN PERIODS OF GREATLY REDUCED VISIBILITY,
WITH SOME BLOWING OF THAT SNOW ONLY ADDING TO THE EXPECTED TRAVEL
DIFFICULTIES.
GIVEN ALL THE ABOVE, HAVE GONE AHEAD AND ISSUED BOTH COLD WEATHER
AND WINTER WEATHER ADVISORIES WITH THIS FORECAST PACKAGE. WHILE
CRITERIA FOR BOTH MAY NOT STRICTLY BE MET, EXPECTED SIGNIFICANT
IMPACTS FROM VERY COLD TEMPERATURES AND AREAS OF GREATLY REDUCED
VISIBILITY WARRANTED THEIR ISSUANCE.
LONG TERM /MONDAY NIGHT THROUGH SUNDAY/
ISSUED AT 305 PM EST SUN JAN 19 2025
PATTERN SYNOPSIS AND FORECAST DETAILS:
A DIGGING TROUGH WILL CONTINUE BITTERLY COLD TEMPERATURES ACROSS
THE NORTHWOODS. COLD ARCTIC AIR ADVECTING INTO THE REGION WILL DROP
TEMPERATURES INTO THE NEGATIVE SINGLE DIGITS MONDAY NIGHT AND
NEGATIVE DOUBLE DIGITS FOR TUESDAY NIGHT. DAYTIME HIGHS FOR TUESDAY
LOOK TO SIT JUST ABOVE THE NEGATIVES IN THE SINGLE DIGITS (COLDEST
ACROSS INTERIOR AREAS AND IN THE EASTERN U.P.) WITH SOUTHERLY FLOW/
WARMER AIR WORKING BACK INTO THE REGION FOR WEDNESDAY, BRINING
TEMPERATURES BACK INTO THE TEENS. ALONG WITH ALREADY BITTERLY COLD
TEMPERATURES, OCCASIONALLY BREEZY WINDS WILL KEEP APPARENT
TEMPERATURES BELOW ZERO FOR MANY AREAS EVEN DURING THE DAY, WITH
WIND CHILL VALUES VERY LIKELY TO APPROACH CRITICAL THRESHOLDS OF
-15F ACROSS PARTS OF NORTHERN LOWER... THE EASTERN U.P. ALSO LOOKS
VERY LIKELY TO APPROACH CRITICAL THRESHOLDS OF -20F MONDAY NIGHT
INTO TUESDAY MORNING AND AGAIN TUESDAY NIGHT INTO WEDNESDAY. WITH
TEMPERATURES AND WIND CHILL VALUES LIKE THESE, FROSTBITE WILL BE
POSSIBLE IN AS LITTLE AS 15-30 MINUTES WITH EXPOSED SKIN, SO BE SURE
TO TAKE THE PROPER PRECAUTIONS AND PREPARE YOURSELF AND OTHERS
ACCORDINGLY. ALONG WITH COLD TEMPERATURES, LAKE EFFECT SNOW SHOWERS
LOOK TO LINGER INTO THE FIRST HALF OF THE WEEK. FORECAST SOUNDINGS
DISPLAY A DEEP CONVECTIVE BOUNDARY LAYER UPWARDS OF 700MB AT TIMES,
BUT ALMOST ENTIRELY AT OR BELOW -20C. THEREFORE, THE NATURE OF THE
SNOWFLAKES IS EXPECTED TO BE SMALLER/FINE, WHICH CAN BE EASILY
TRANSPORTED BY WINDS/ PASSING CARS. WHILE SNOW SHOWERS MAY BE RATHER
ROBUST AT TIMES, SMALL FLAKE SIZE (COLUMNS/ PLATES VS. LARGE
DENDRITES) MAY LIMIT ACTUAL SNOW ACCUMULATIONS, BUT RESULT IN
SIGNIFICANTLY REDUCED VISIBILITY AND TREACHEROUS TRAVEL AT TIMES IN
THE SNOW BELTS, ESPECIALLY FACTORING IN ANY WIND EXACERBATING THESE
ISSUES. LOOKING AT THE LATTER HALF OF THE WEEK, A CLIPPER WILL
INFLUENCE THE AREA AND LOOKS TO INITIATE WIDESPREAD/SYNOPTIC SNOW
ACROSS NORTHERN MICHIGAN WITH MOISTURE BEING PUMPED INTO THE REGION
FROM ONGOING SOUTHERLY FLOW. WITH THIS, GUIDANCE IS ALSO HINTING AT
SOME DECENT LAKE ENHANCEMENT POTENTIAL ON SOUTHWEST FLOW, MAKING
THIS SOMETHING WE'LL HAVE TO CONTINUE TO WATCH AS THE PREVIOUS
FORECASTER EXPLAINED.
AVIATION /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 1150 PM EST SUN JAN 19 2025
LAKE CONVECTION TO CONTINUE IN COLD AIR COMING ACROSS THE UPPER
LAKES. KPLN/KTVC/KMBL WILL BE IMPACTED BY SNOW BANDS COMING IN
OFF LAKE MICHIGAN WITH PERIODS OF IFR VISIBILITIES IN HEAVIER
SNOW SHOWERS. KCIU/KAPN EXPECTED TO REMAIN VFR INTO MONDAY
MORNING.
APX WATCHES/WARNINGS/ADVISORIES
MI...WINTER WEATHER ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ016-017-
020-022-025-031-086-099.
COLD WEATHER ADVISORY UNTIL NOON EST WEDNESDAY FOR MIZ016>018-
020>036-041-042-086>088-095>099.
WINTER STORM WARNING UNTIL 4 PM EST MONDAY FOR MIZ021.
WINTER WEATHER ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ027.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST MONDAY FOR LMZ342-344>346.
UPDATE...JPB
SHORT TERM...MSB
LONG TERM...NSC
AVIATION...JPB
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