379
FXUS63 KAPX 170409
AFDAPX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
1109 PM EST MON DEC 16 2024
KEY MESSAGES
- RAIN TO SNOW SHOWER TRANSITION LATER TONIGHT.
- WINDY PERIOD OVERNIGHT/TUESDAY.
- LAKE EFFECT SNOW MID WEEK, SYSTEM SNOW LATE WEEK.
UPDATE
ISSUED AT 1047 PM EST MON DEC 16 2024
CURRENT FORECAST LARGELY REMAINS ON TRACK AS SHOWERS HAVE LARGELY
MOVED OUT OF NORTHERN MICHIGAN AND DRIZZLE HAS COMMENCED ACROSS
PARTS OF THE AREA. TEMPERATURES WILL CONTINUE TO COOL WITH TIME AND
AN UPTICK IN PRECIP INTENSITY IS ANTICIPATED LATER TONIGHT INTO
TUESDAY MORNING, EVENTUALLY TRANSITIONING LIGHT RAIN/DRIZZLE TO
LIGHT SNOW/FLURRIES ACROSS PARTS OF THE EASTERN U.P. AND INTERIOR
HIGHER TERRAIN OF NORTHERN LOWER MICHIGAN. LESS THAN 1" OF
ACCUMULATION IS EXPECTED FOR MOST AREAS THROUGH TUESDAY.
SHORT TERM /THROUGH TUESDAY/
ISSUED AT 357 PM EST MON DEC 16 2024
PATTERN SYNOPSIS/FORECAST: SHORT WAVE TROUGH APPROACHING FROM THE
SOUTHWEST AT MID AFTERNOON...SPINNING ITS WAY ACROSS SOUTHERN
WISCONSIN PER WATER VAPOR IMAGERY. SCATTERED RADAR RETURNS ALONG
THE DEFORMATION SIDE OF THIS WAVE. MORE WIDESPREAD SHOWERS THAT
EARLIER MOVED ACROSS NORTHERN MICHIGAN NOW INTO LAKE HURON WITH SOME
DRIZZLE DEVELOPING IN ITS WAKE. ALSO GETTING SOME CLOUD TOP COOLING
OVER CENTRAL UPPER AND INTO LAKE SUPERIOR. 18Z SURFACE ANALYSIS
SHOWS A 1001MB LOW OVER NORTHWEST ONTARIO...COLD/OCCLUDED FRONT ARCS
SOUTH ACROSS CENTRAL UPPER/WESTERN LOWER MICHIGAN/INDIANA.
SHORT WAVE TROUGH OVER SOUTHERN WISCONSIN EXPECTED TO PROPAGATE
EASTWARD ACROSS THE SOUTHERN HALF OF LOWER MICHIGAN THIS EVENING...
ALONG WITH A COUPLE OF REINFORCING WAVES OVERNIGHT INTO TUESDAY
MORNING. DEEP LAYER CYCLONIC FLOW WRAPS COLDER AIR INTO THE UPPER
LAKES REGION TONIGHT...AS WELL AS SOME DEEPER LAYER MOISTURE ACROSS
UPPER AND FAR NORTHERN LOWER MICHIGAN OVERNIGHT INTO THE FIRST PART
OF TUESDAY.
PRIMARY FORECAST CONCERNS:
RAIN TO SNOW SHOWER TRANSITION LATER TONIGHT: THINK THERE ARE
SEVERAL OPPORTUNITIES FOR PRECIPITATION TONIGHT...MOSTLY LIGHT AND
SHOULD NOT GET OUT OF HAND. THERE WILL BE SOME ONGOING DRIZZLE
AHEAD OF THE COLD/OCCLUDED FRONT...THEN SOME SHOWERS WITH THE
APPROACHING SHORT WAVE TROUGH OVER WISCONSIN. NARROW BAND OF
PRECIPITATION WITH THE WAVE ITSELF AT MID AFTERNOON...BUT GETTING
SOME CLOUD TOP COOLING OVER LAKE MICHIGAN (GRAVITY WAVES??) SO THAT
MAY ALLOW SOME EXPANSION OF SHOWER COVERAGE. ANOTHER VORTICITY
CENTER NEAR THE MINNESOTA ARROWHEAD IS SPREADING SOME LIGHT SNOW
ACROSS NORTHEAST MINNESOTA TOWARD LAKE SUPERIOR...SO EXPECT SOME OF
THAT LATER THIS EVENING AT LEAST INTO EASTERN UPPER. THIS COULD BE
ENHANCED BY INCREASING INSTABILITY OVER LAKE SUPERIOR BUT
TRAJECTORIES ARE ALMOST DUE WEST SO THINK THE BETTER QPF ENHANCEMENT
WILL BE NORTH OF WHITEFISH POINT BUT COULD BE CLOSE. AND THEN WITH
THE ARRIVAL OF THE COLD AIR LATER THIS EVENING SHOULD SEE AN
INCREASE IN RELATIVELY SHALLOW CONVECTION OFF NORTHERN LAKE
MICHIGAN. CURRENT THOUGHTS ARE THAT THIS WILL BE MOSTLY NORTH OF M-
72...BUT WONDERING ABOUT OVERALL EVOLUTION WITH INVERSION
HEIGHTS...WHILE EXPECTED TO CLIMB ABOVE 800MB WILL STRUGGLE TO REACH
TEMPERATURES COLD ENOUGH FOR ICE NUCLEATION. SO CONCERNED THAT WE
COULD SEE A MIX OF SNOW AND DRIZZLE OR PERHAPS FREEZING DRIZZLE
ESPECIALLY ACROSS THE INTERIOR HIGHER TERRAIN. FORECAST WILL CARRY
A MIX SOUTH OF THE BRIDGE AND MORE OF A TRANSITION TO SNOW ACROSS
EASTERN UPPER WHERE LINGERING SURFACE BASED WARM LAYER EXPECTED TO
BE SHALLOWER.
LAKE CONVECTION WILL CONTINUE TUESDAY BUT NOT EXPECTED TO BE OVERLY
INTENSE ESPECIALLY WITH WEAKENING THERMODYNAMICS AS THE DAY
PROGRESSES. OVERALL ACCUMULATIONS UNDER 2 INCHES ACROSS NORTHERN
CHIPPEWA COUNTY AND IN THE HIGHER TERRAIN IN THE GAYLORD
VICINITY.
WINDY PERIOD OVERNIGHT/TUESDAY: EXPECTING WINDS TO INCREASE LATER
TONIGHT WITH ONSET OF COLD ADVECTION AND A TIGHTENING PRESSURE
GRADIENT. GUSTS OF 20-30MPH EXPECTED OVERNIGHT INTO AT LEAST THE
FIRST HALF OF TUESDAY...GUSTS OF 30+MPH ALONG THE NORTHWEST LOWER
LAKESHORE AND UP NEAR WHITEFISH POINT.
LONG TERM /TUESDAY NIGHT THROUGH MONDAY/
ISSUED AT 357 PM EST MON DEC 16 2024
PATTERN SYNOPSIS AND FORECAST:
WEAK FEATURE ALOFT SKIRTS BY THE AREA LATER TUESDAY INTO EARLY
WEDNESDAY, WITH MOST OF THE ENERGY/MOISTURE EXTENDING SOUTHWARD
ACROSS OH VALLEY AND SOUTH. LINGERING MINOR LAKE EFFECT SNOW SHOWERS
DURING THIS TIME. NEXT VIGOROUS, BUT TRANSIENT, UPPER TROUGH MOVES
TO THE SOUTHEAST ACROSS N MI MIDDAY-EVENING WEDNESDAY (PRODUCING A
FEW LIGHT SNOW SHOWERS), LIKELY EJECTING EASTWARD BY THE OVERNIGHT
HOURS. THUS, BOUNDARY LAYER WINDS SHIFT AROUND TO THE NORTHWEST, LOW
LEVEL TS DROP, AND THUS LAKE EFFECT SNOWS DEVELOP FOR NORTHWEST
SNOWBELTS. THE PROGGED ENVIRONMENT IS CONDUCIVE, WITH DEEP ENOUGH
INVERSION HEIGHTS, GOOD ENOUGH MOISTURE QUALITY. BUT JUST LOOKS LIKE
TOO MODEST AND TRANSIENT OF AN ENVIRONMENT FOR GOOD SNOWS WITH THIS
EVENT. THUS, GENERALLY LIGHT SNOW ACCUMULATIONS EXPECTED, BUT COULD
SEE A BURST OF SNOW WEDNESDAY EVENING/EARLY OVERNIGHT KALKASKA
COUNTY AND VICINITY. MOST OF THE SNOWBELTS WILL SEE A LIGHT
ACCUMULATIONS, MAYBE A FEW INCHES, BUT COULD BE A FEW ISOLATED
LOCATIONS A LITTLE MORE THAN THAT. COOLER AIRMASS DOES SETTLE IN
THOUGH FOR THE END OF THE WEEK BEHIND THIS SYSTEM WITH HIGH
TEMPERATURES IN THE MID TO UPPER 20S, NOT TOO TERRIBLY COLD FOR THIS
TIME OF YEAR.
NEXT SYSTEM TO WATCH WILL BE ANOTHER VIGOROUS UPPER LOW DIVING TO
THE SOUTHEAST LATE NEXT WEEK FROM THE N PLAINS AND UPPER MIDWEST.
STILL UNCERTAINTY IN THE EXACT PLACEMENT OF LIGHT TO MODERATE SNOWS
BUT GUIDANCE CONTINUES TO SHOW THE POTENTIAL FOR THE LIFT ASSOCIATED
WITH THIS SYSTEM TO OVERSPREAD N MI. ENS GUIDANCE MEANS GENERALLY
SHOW A COUPLE OF INCHES POSSIBLE, WITH MODERATE PROBS FOR AROUND 3".
COUPLING DETERMINISTIC WITH PROBABILISTIC GUIDANCE, LOWER END
SCENARIO AT THIS TIME ~1-3" WITH HIGH END SCENARIO PERHAPS 3-6" IF
THE MAIN AREA OF LIFT IMPACTS A BULK OF THE COUNTY WARNING AREA.
BEHIND THIS SYSTEM WILL BE ANOTHER SHOT OF COLD AIR, DROPPING HIGHS
INTO THE TEENS AND 20S AND LOWS IN THE TEENS TO SINGLE DIGITS THIS
WEEKEND. THE COLD AIR COUPLED WITH MORE NORTHERN STREAM QUICK
HITTING PIECES OF ENERGY LOOK TO PRODUCE MORE LAKE EFFECT SNOWS
DURING AND BRIEFLY AFTER THIS TIME PERIOD.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 1107 PM EST MON DEC 16 2024
FLIGHT CONDITIONS CONTINUE TO IMPROVE BEHIND THE FRONT. CIGS HAVE
RISEN BACK TO MVFR ACROSS ALL OBSERVATION SITES AND VSBYS HAVE
IMPROVED TO VFR FOR MOST AREAS AS WELL. CURRENT EXPECTATION IS AN
UPTICK IN PRECIP INTENSITY LATER TONIGHT INTO TUESDAY MORNING. ASIDE
FROM LOCALIZED DROPS IN VSBY POSSIBLE, FLIGHT CONDITIONS ARE LARGELY
EXPECTED TO REMAIN THE SAME THROUGH THE TAF PERIOD. WEST-SOUTHWEST
WINDS WILL GRADUALLY TURN TO WEST WINDS THROUGH TUESDAY WITH
SUSTAINED WIND SPEEDS AROUND 10-15 KTS AND GUSTS BETWEEN 20-30 KTS
AT TIMES THROUGH THE AFTERNOON.
APX WATCHES/WARNINGS/ADVISORIES
MI...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST TUESDAY FOR LHZ345>349.
SMALL CRAFT ADVISORY UNTIL 4 PM EST TUESDAY FOR LMZ323-341-342-
344>346.
SMALL CRAFT ADVISORY UNTIL 4 PM EST TUESDAY FOR LSZ321.
SMALL CRAFT ADVISORY UNTIL 7 PM EST TUESDAY FOR LSZ322.
UPDATE...DJC
SHORT TERM...JPB
LONG TERM...JLD
AVIATION...DJC
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