033
FXUS63 KAPX 171747
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1247 PM EST FRI JAN 17 2025
KEY MESSAGES
- A LIGHT MIX OF RAIN/SNOW THIS AFTERNOON INTO THIS EVENING WITH
GUSTY WINDS.
- BITTERLY COLD TEMPS SUNDAY THROUGH TUESDAY.
- PERIODS OF LAKE EFFECT SNOW WITH BLOWING/DRIFTING.
UPDATE
ISSUED AT 1030 AM EST FRI JAN 17 2025
FORECAST REMAINS ON TRACK WITH LIGHT RETURNS SHOWING ON RADAR
THIS MORNING, MAINLY ACROSS EASTERN UPPER MICHIGAN. RAIN/ SNOW
SHOWERS WILL SPREAD ACROSS THE NORTHWOODS TODAY AS SOUTHERLY
FLOW GRADUALLY TURNS NW BY LATE TONIGHT AFTER A COLD FRONTAL
PASSAGE, INITIATING LAKE EFFECT SNOW SHOWERS. FOR MORE DETAILS,
PLEASE SEE SHORT-TERM DISCUSSION BELOW.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 345 AM EST FRI JAN 17 2025
BRISK WITH A LIGHT MIX OF RAIN/SNOW THIS AFTERNOON INTO THIS
EVENING...
LOW LEVEL RIDGE AXIS CURRENTLY EXTENDS FROM EASTERN ONTARIO THRU
MICHIGAN INTO THE OHIO VALLEY EARLY THIS MORNING...RESULTING IN DRY
BUT MAINLY CLOUDY CONDITIONS ACROSS OUR CWA ATTM. MEANWHILE...LOW
PRESSURE CONTINUES TO DEVELOP WELL UPSTREAM...CURRENTLY CENTERED
NORTH OF THE DAKOTAS.
LOW CENTER WILL DRIVE EASTWARD THRU ONTARIO TODAY INTO THIS
EVENING...REACHING JAMES BAY LATE TONIGHT. RELATIVELY WARM AND MOIST
AIR WILL SURGE NORTHWARD AHEAD OF THE ASSOCIATED COLD FRONT...
PUSHING TEMPS INTO THE MID TO UPPER 30S ACROSS OUR ENTIRE CWA THIS
AFTERNOON INTO THIS EVENING. LIGHT SYNOPTICALLY-DRIVEN PRECIP WILL
DEVELOP INITIALLY ACROSS UPPER MICHIGAN AND THE STRAITS AREA THIS
MORNING...AND WILL THEN SPREAD INTO MUCH OF NORTHERN LOWER MICHIGAN
THIS AFTERNOON AND EVENING. TEMP PROFILES SUGGEST PRECIP TYPE WILL
LIKELY BE A MIX OF LIGHT RAIN AND LIGHT SNOW...EVEN ACROSS EASTERN
UPPER MICHIGAN. EXPECT LITTLE TO NO SNOW ACCUMULATION TODAY... WITH
GENERALLY LESS THAN AN INCH OF NEW SNOW EXPECTED TONIGHT (POSSIBLY A
BIT MORE THAN AN INCH AROUND WHITEFISH POINT). ALSO...S/SW LOW
LEVEL WINDS WILL STRENGTHEN AHEAD OF THAT COLD FRONT TODAY INTO
EARLY EVENING...CAUSING SOME BLOWING SNOW AT TIMES.
COLD FROPA WILL OCCUR TONIGHT...WITH STRONG LOW LEVEL CAA COMMENCING
IMMEDIATELY BEHIND THE FRONT. LOW LEVEL WINDS WILL SHIFT TO THE WEST
LATER THIS EVENING AND EVENTUALLY TO THE NW OVERNIGHT IN THE WAKE OF
THE DEPARTING COLD FRONT. LIGHT SYNOPTIC PRECIP EVENT WILL BEGIN TO
TRANSITION TO A NW FLOW LAKE EFFECT EVENT ONCE CAA BEGINS AND LOW
LEVEL WINDS SHIFT TO THE NW BEHIND THE COLD FRONT. AGAIN...DO NOT
EXPECT SIGNIFICANT SNOW ACCUMULATIONS THRU TONIGHT. OVERNIGHT LOWS
WILL DROP INTO THE TEENS TO LOWER 20S AS MUCH COLDER AIR
ARRIVES.
LONG TERM /SATURDAY THROUGH THURSDAY/
ISSUED AT 345 AM EST FRI JAN 17 2025
PATTERN SYNOPSIS/FORECAST:
RIDGE AXIS BUILDING INTO THE UPPER MIDWEST/GREAT LAKES IN THE WAKE
OF SHARP TROUGH AXIS AND ATTENDANT CLIPPER NOW SLIDING OUT INTO
EASTERN CANADA/NEW ENGLAND. THIS IS AHEAD OF POTENT SWATH OF PV AND
ATTENDANT SURFACE RESPONSE PLOWING THROUGH WESTERN CANADA ON 80+KT
POLAR JET STRETCHING ACROSS THE NW US/SW CANADIAN BORDER...DOWN
ACROSS THE GREAT LAKES INTO THE MID-ATLANTIC. PLENTY OF COLD
ADVECTION TO BE HAD WITH THIS THROUGH THE ENTIRE COLUMN...AS
TRAJECTORIES TURN MORE NORTHERLY, OFF THE POLE, OVER NORTHERN
CANADA...NORTH OF A SECOND COLD FRONT STRETCHING FROM
ALBERTA/BRITISH COLUMBIA TO THE SURFACE LOW IN S. MANITOBA. SOME
DEEPER MOISTURE AHEAD OF THIS FEATURE AS WELL OVER CENTRAL CANADA
INTO THE UPPER MIDWEST (PWATS AROUND 0.4IN IS UNUSUAL UP HERE FOR
THIS TIME OF YEAR)...WITH STRONG WARM ADVECTION AHEAD OF THIS
FEATURE FROM THE NORTHERN PLAINS INTO THE UPPER MIDWEST. (850MB
TEMPS RISING TO -10C OR WARMER ATTM OVERHEAD.) PATTERN CHANGE IN THE
WORKS UPSTREAM...WITH WESTERN RIDGE AXIS NOW RETROGRADING INTO THE
GULF OF ALASKA...WITH EASTWARD PROGRESSION OF UPPER LOW THAT HAS
BEEN PLAGUING SOCAL.
RIDGE AXIS QUICKLY DEPARTS EASTWARD TODAY...AS INITIAL TROUGH AXIS
SLAMS INTO THE UPPER GREAT LAKES...SETTING THE STAGE FOR THE
REMAINDER OF THE WEEKEND. STRONG/EFFICIENT NORTHERLY FLOW OFF THE
POLE TO DEVELOP FRIDAY INTO SATURDAY AS RIDGING BUILDS OVER THE GULF
OF ALASKA...WITH ADDITIONAL SHORTWAVE TROUGHS TO DROP INTO THE
MIDWEST THROUGH THE WEEKEND, REINFORCING THE UNUSUALLY DEEP N-S
ORIENTED LONGWAVE TROUGH AXIS ACROSS THE CENTRAL US GOING INTO THE
START OF THE NEXT WORK WEEK. CORE OF THE COLDEST AIR CURRENTLY LOOKS
TO REMAIN TO OUR WEST GOING INTO THE START OF NEXT WEEK (THANKS TO
THE AGGREGATE WARMTH OF THE GREAT LAKES)...WITH HIGHS IN THE SINGLE
DIGITS LIKELY FOR MUCH OF NORTHERN MICHIGAN. UPSTREAM RIDGING
APPEARS TO BREAK DOWN FOR MONDAY AND BEYOND...WHICH SHOULD DISRUPT
THE TAP OF POLAR AIR, PARTICULARLY FOR MIDWEEK AND BEYOND FOR OUR
AREA IN THE WAKE OF ONE LAST TROUGH AXIS TUESDAY FROM THIS ROUND OF
COLD AIR. WILL ULTIMATELY LOOK FOR SOME SEMBLANCE OF MODERATION IN
TEMPERATURES FOR MID TO LATE WEEK...THOUGH THERE ARE SIGNALS
TROUGHING WILL AGAIN TRY TO TAKE SHAPE SOMEWHERE OVER THE CENTRAL US
GOING INTO THE LATTER PART OF NEXT WEEK. PATTERN FAVORS LAKE EFFECT
SNOW THROUGH MUCH OF THE PERIOD TO KEEP THINGS OTHERWISE ACTIVE;
WILL HAVE TO MONITOR THE EVOLUTION OF THE UPSTREAM PATTERN FOR LATE
WEEK TO SEE IF A MORE SYNOPTIC-TYPE ACTIVE SETUP COULD BE IN PLAY
FOR A CHANGE.
PRIMARY FORECAST CONCERNS:
COLD TEMPS SUNDAY THROUGH TUESDAY...NICE LITTLE COLD SNAP ON THE
WAY...RETURN INTERVALS FOR THIS KIND OF COLD GENERALLY RUNNING
AROUND 5-10 YEARS OR SO FOR OUR AREA (AGAIN, THANKS TO THE GREAT
LAKES FOR KEEPING US WARMER THAN POINTS UPSTREAM). 850MB TEMPS
LIKELY TO APPROACH -25C HERE (COULD BE BELOW -30C UPSTREAM),
SUPPORTIVE OF SURFACE TEMPS (DAYTIME HIGHS) NEAR ZERO, EVEN HERE IN
THE PROTECTIVE BLANKET OF THE GREAT LAKES. SIGNALS FOR DRAINAGE FLOW
OUT OF ONTARIO INTO THE EUP SUGGEST HIGHS MAY STRUGGLE TO REACH ZERO
FOR PLACES NEAR THE SOO, AS DRAINAGE FLOW COULD ULTIMATELY LEAD TO
COOLER HIGH TEMPS FOR A GIVEN DIURNAL SWING...THOUGH DRAINAGE FLOW
COULD CERTAINLY LEAD TO COLDER LOWS THAN A TYPICAL DIURNAL SWING
(APPROX 15 DEGREES FOR THIS TIME OF YEAR IN THE SOO). HOWEVER...MAY
NOT BE IMPOSSIBLE TO APPROACH SUB-ZERO HIGHS CLOSER TO CENTRAL LOWER
MI TUESDAY AS FLOW TURNS MORE WESTERLY AND ULTIMATELY LIMITS THE
AMOUNT OF LAKE MODIFICATION THE AIR MASS WOULD HAVE TO ENDURE
(COMPARED TO NW FLOW HAVING TO TRAVERSE OVER LAKE SUPERIOR AND
NORTHERN LAKE MI...THOUGH ALL THE LAKES DO HAVE SOME IMPACT ON
HEATING TO SOME DEGREE). CLOUDY AREAS WILL HAVE A MUCH SMALLER
DIURNAL SWING, WITH POTENTIAL FOR WARMER (RELATIVELY) LOWS AND
COLDER HIGHS (WHICH, WITH THAT AFOREMENTIONED BACKING FLOW, COULD
LEAD TO COLDER LOWS TUESDAY MORNING IN A FEW SPOTS). GREATEST
LIKELIHOOD FOR LOW TEMPS TO FALL INTO THE NEGATIVE TEENS F (PERHAPS
COLDER) FOR THE EUP WHERE AFOREMENTIONED DRAINAGE FLOW WILL BE IN
PLAY; ELSEWHERE, FOR NOW WILL HOLD OFF ON LOWERING LOWS TOO
DRAMATICALLY (PARTICULARLY FOR NORTHERN LOWER)...BUT CERTAINLY
POSSIBLE SOME AREAS OF NORTHERN LOWER COULD DROP INTO THE NEGATIVE
TEENS WHERE CLEARING TAKES PLACE DURING THE OVERNIGHTS. MONDAY INTO
MONDAY NIGHT IN PARTICULAR LOOKS TO BE THE COLDEST NIGHT OF THE
BUNCH ATTM. THINK THERE IS A DECENT SHOT AT APPROACHING COLD WEATHER
ADVISORY CRITERIA ACROSS NORTHERN LOWER, AS THIS AREA SHOULD HAVE
SLIGHTLY BREEZIER FLOW...WITH PROB GUIDANCE SUGGESTING A REASONABLE
SHOT AT WIND CHILLS OF -15F ACROSS THIS REGION AT TIMES (ESP AT
NIGHT). IT MAY BE TRICKIER TO GET COLDER WIND CHILLS NEAR THE SOO,
AS WINDS /SHOULD/ BE LIGHTER...THOUGH IT WON'T TAKE MUCH TO APPROACH
-20F WIND CHILLS DURING THE OVERNIGHTS IF WE END UP AS COLD AS THE
CURRENT FORECAST SAYS.
PERIODS OF LAKE EFFECT SNOW...FOLLOWING THE INITIAL FROPA SATURDAY
MORNING (STILL APPROX A 6HR TIMING UNCERTAINTY IN HOW QUICKLY IT
DEPARTS THE CWA EARLY SUNDAY AM), WILL EXPECT LAKE EFFECT TO BEGIN
TO RAMP UP THROUGH THE DAY AMID FALLING TEMPS. AS THIS BRUTALLY COLD
AIRMASS OOZES AROUND THE WARMER GREAT LAKES...EXPECT LAKE AGGREGATE
TROUGHING TO DRAMATICALLY STRENGTHEN OVER THE REGION...WITH
POTENTIAL FOR IT TO LARGELY FOCUS ITSELF NW-SE NEAR THE ONTARIO
COAST OF LAKE SUPERIOR WHERE THE THERMAL GRADIENT SHOULD BE
TIGHTEST, AND DO HAVE CONCERNS THIS WILL RESULT IN A HEFTY BAND OF
LAKE EFFECT SNOW FOR PARTS OF CHIPPEWA COUNTY SATURDAY NIGHT INTO
SUNDAY MORNING. NOT IMPOSSIBLE THE COLD AIR DRAINAGE OUT OF ONTARIO
COULD BE STRONG ENOUGH TO SHIFT THE FGEN AXIS EASTWARD WITH TIME
SUNDAY INTO MONDAY AND SHIFT THE FOCUS OF HEAVIER LAKE EFFECT
AROUND, NOTING PRESSURE GRADIENT OVER ONTARIO WILL BE A BIT WEAKER
THAN OVER THE WI SIDE OF THE LAKE AGGREGATE TROUGH. PLUS, THINK SOME
SUBTLE WIND SHIFTS WILL PROGRESS THROUGH THE REGION OVER THIS 48-
72HR PERIOD WITH A SERIES OF NIBLETS PASSING THROUGH...PARTICULARLY
SUNDAY NIGHT INTO MONDAY, AT WHICH POINT IT APPEARS THE LAKE
AGGREGATE TROUGH COULD BACK A LITTLE MORE ZONAL IN ORIENTATION,
POTENTIALLY FOCUSING LAKE BANDS INTO MORE OF A WNW OR W FLOW REGIME,
AS OPPOSED TO THE MORE NW IDEA EXPECTED FOR SATURDAY INTO SUNDAY.
OTHER CONCERN WITH THE LIGHTER FLOW IS POTENTIAL FOR THINGS LIKE
MESOLOWS TO DEVELOP...WHICH COULD LEAD TO LOCALIZED MORE INTENSE
SNOWS THAN CURRENTLY PREDICTED (THESE CAN BE HARD TO PREDICT ANYHOW).
INVERSION HEIGHTS THROUGH THE WEEKEND COULD FLOAT AROUND 700MB
(APPROX 9-12KFT)...SUPPORTIVE OF DEEPER, POTENTIALLY MORE VIGOROUS
LAKE CONVECTION. HOWEVER, WITH THE VERY COLD AIR MASS IN
PLACE...THERMAL PROFILES WILL FAVOR A MUCH MORE DRY, POWDERY SNOW
COMPARED TO THE LAKE EFFECT WE'VE SEEN RECENTLY...WHICH IS MUCH MORE
LIKELY TO CAUSE BLOWING/DRIFTING AND LEAD TO VISIBILITY REDUCTIONS
THAN RECENT SNOWFALL. EVEN IF SNOWFALL AMOUNTS REMAIN
LIMITED...HAZARDOUS TRAVEL CONDITIONS MAY VERY WELL OCCUR
ANYWAY...PARTICULARLY ACROSS NORTHERN LOWER, WHICH CURRENTLY APPEARS
MORE FAVORED FOR SLIGHTLY STRONGER WINDS (ALBEIT MAYBE 5-10KTS VS 3-
5KTS)...WHICH, COMBINED WITH THE DANGEROUS COLD, COULD VERY WELL BE
PROBLEMATIC FOR ANYONE UNPREPARED WHO UNEXPECTEDLY GETS STRANDED.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1230 PM EST FRI JAN 17 2025
MVFR TO LOW VFR CONDITIONS ARE EXPECTED THROUGH THE ISSUANCE
PERIOD. WARMER AIR WILL CREATE A LIGHT MIX OF RAIN AND SNOW
SHOWERS ACROSS THE NORTHWOODS INTO THIS EVENING AHEAD OF A COLD
FRONTAL PASSAGE LATE TONIGHT, SHIFTING WINDS NW. LLWS IS
EXPECTED TO DEVELOP TONIGHT AHEAD OF THE AFOREMENTIONED COLD
FRONT. GUSTY WINDS WILL GRADUALLY DECREASE THROUGH THE EVENING
INTO TONIGHT, BUT REMAIN BREEZY INTO SATURDAY WITH GUSTS 15-25
KNOTS.
APX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR
LHZ345>347.
GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LHZ348-349.
GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LMZ323-341-342-
344>346.
SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR LSZ322.
GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ321.
UPDATE...NSC
SHORT TERM...MLR
LONG TERM...FEF
AVIATION...NSC
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