Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 080836
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
336 AM EST Fri Dec 8 2017

.NEAR TERM...(Today through Tonight)
Issued at 336 AM EST Fri Dec 8 2017

...Accumulating lake effect snow continues...

High impact weather potential...lake effect/enhanced snow,
heaviest this morning, and again late tonight.

Shortwave digging toward Superior and central/eastern upper MI early
this morning. This has carved out a weak (1004mb) surface low
just east of Superior. 1000-850mb winds have backed to the wsw in
response. That had been keeping the prime Superior band (and it
is a doozy) north of Whitefish Pt, but that is starting to move
onshore now. Meanwhile, lake effect/enhanced snow continues off
of Lake MI into nw lower MI, the Straits region, on toward
Drummond Isl. Heaviest snow has been in Emmet Co. Plenty going on
in this near term period, and surprise of surprises, most of it
involves snow.

Eastern upper today: As the digging upper trof approaches, the
surface low will deepen somewhat in the pre-dawn hours. It will then
kick eastward after 12Z. A trailing surface trof will get dragged
down into eastern upper, and the dominant band up there will
(is) coming along for the ride. While that all happens, the
ongoing activity skirting far se Chip Co will get kicked southward
out of eastern upper. There will be a 2-3 hour window of some
potentially impressive snowfall rates, near and north of Paradise,
over the next several hours This dominant band will weaken as it
moves south, with wnw-flow lake effect for the rest of the day in
a much drier airmass (2-5 inch accums, roughly near and north of
M-28).

Northern lower today: Lake enhancement will continue to target
locales from Leland to Cheboygan, with particular emphasis on Emmet
Co, til a bit past sunrise. Winds will start to veer down here as
well as the morning proceeds and the surface low exits eastward. And
again, this will also correspond with the arrival of drier air,
which persists into the afternoon. Could well see total overnight/
morning accums in the 4-8" inch range from Ltl Trav Bay up to
PLN. Drier air will take a toll as this activity moves inland this
morning and thru midday. It is interesting to see the HRRR
maintain some 0.25" liquid QPF into parts of Antrim/Otsego (other
models minor things out quickly as move se away from Lake MI).
Will still allow for some accums to around 3 inches in
Antrim/Otsego. Will still be dwindling pops somewhat as we move
thru the afternoon, and am a bit concerned that the advisory for
Charlevoix/Antrim/Otsego runs too long. But will take a cautious
approach to any drastic headline changes at this time.

Max temps today mid 20s to around 30f.

Tonight, another vigorous shortwave dives into the western lakes,
starting the evening near DLH and ending it over southern Lake MI.
An associated surface low will move into w central lower MI, with
enhanced synoptic support for precip. Expect a light synoptic snow
to move into much of northern lower MI from mid evening to the early
overnight hours. Pure synoptic snow will be higher downstate than
here, given the path of the shortwave and associated stronger
forcing. Synoptic snow up here will be generally less than inch,
perhaps a bit more in Gladwin/Arenac. But 850mb temps are in the
lower minus teens, so we will see lake enhancement where winds are
onshore. That will occur for a period into ne lower MI north of
APN, where winds are out of the east (vs southerly to the south).
This will especially occur (mainly overnight) into nw lower MI
(from Leelanau south), with weak westerlies becoming somewhat
stronger n to nne winds. Snowfall amounts of 2-5" are reasonable
for this portion of nw lower, 1-3" across far northern lower MI.
Will refrain from posting any headlines for now.

Relatively little will be going on for much of the night in much of
eastern upper MI. Leftover lake effect will be scraping by
Paradise/Whitefish on weakening wnw flow to start the night. Might
see the opportunity for a mesoscale vortex to form over eastern
Superior in a short period tonight with light winds. That would then
get dragged southward toward central/upper MI overnight as n to nne
winds pick up. Still, hard to go more than an inch or two in far nw
Chip.

Min temps as cold as 10 above in parts of eastern upper, teens to
lower 20s otherwise.

&&

.SHORT TERM...(Saturday through Sunday)
Issued at 336 AM EST Fri Dec 8 2017

...Snow showers ongoing, but generally light snowfall amounts...

High Impact Weather Potential...Snow showers will be ongoing through
much of the period with light nuisance amounts possible.

Pattern Synopsis/Forecast...Potent shortwave trough associated with
a clipper system will rotate through the Great Lakes on Saturday,
with the bulk of its mid-level energy drifting east of northern
Michigan by Saturday evening. A short-duration reinforcing shot of
cold air will accompany this trough, with 850mb temperatures
dropping to around -16C to -18C through Saturday night. A weak
surface ridge will try to nudge into northern Michigan late Saturday
night into early Sunday, quickly displaced by another incoming
clipper system from southern Ontario.

Primary Forecast Concerns...Location and amounts of snowfall through
the period.

A continued favorable setup for additional lake effect snow heading
into the weekend. 850mb temperatures will be dropping through the
day on Saturday, yielding delta Ts around 20 degrees or better.
Plenty of 850-700mb moisture initially, though moisture will begin to
strip out a little from top down by afternoon/evening as rising
heights and a drier airmass settle in behind the departing
shortwave. Northerly low level winds on Saturday will gradually back
to WSW by Sunday, breezy but not particularly strong. So lake effect
snow likely to start the day Saturday in the favored northerly snow
belts (mainly Grand Traverse Bay area and south), aside from some
synoptic snow near Lake Huron associated with the departing
shortwave. With surface ridge and influx of drier air, lake effect
chances will decrease a bit Saturday night, with chances becoming
focused within the westerly flow component snowbelts. Incoming
clipper system on Sunday will brush eastern Upper, with westerly
winds shifting NW with the passage of a cold front. Snowfall amounts
through the weekend not looking menacing -- just nuisance small
amounts. Fluctuating wind direction will help to fan out the lake
effect totals across eastern Upper and northwest Lower. An
increasing pressure gradient on Sunday will make for breezy
conditions with scattered gusts up to 25 mph. Perhaps some isolated
blowing snow, but not expecting anything high impact.

&&

.LONG TERM...(Sunday night through Thursday)
Issued at 336 AM EST Fri Dec 8 2017

High impact weather potential...Ongoing lake effect snow will be
enhanced by periodic snow from passing clipper systems. This could
yield some significant snow totals for some areas.

An unrelenting, active winter pattern for the Great Lakes region
through the period as a persistent longwave trough sits over the
region. A progression of several systems and repeated blasts of
Arctic air look to rotate around the trough at various time. A
clipper system will dive through the Great Lakes late Sunday night
into Monday, with 850mb temperatures dropping to around -20C or
perhaps colder heading into Tuesday. Snowblow, shovel, and repeat as
yet another clipper system rounds the trough Wednesday night into
Thursday, following a nearly identical track. In between these
systems, of course, will be ongoing lake effect...reinforced by the
periodic shots of cold, Arctic air. Northerly and northwesterly flow
snow belts appear to be most favored through the period. Taking a
cursory look at BUFKIT data and GEFS plumes, snowfall from the lake
effect combined with the passing clipper systems could be enough to
warrant headlines for some areas, but time will tell of course as
details become clearer in the coming days.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1138 PM EST Thu Dec 7 2017

Periods of lake effect snow will continue through Friday night
with more synoptically enhanced lake effect snow anticipated this
morning and Friday evening. Three separate disturbances aloft
will allow for prevailing MVFR CIGS at various times for the
airports, mostly the NW lower airports. One is crossing the region
now, then another late tonight into Friday morning, which is also
the one looking to bring the best lake effect snows to mainly
PLN, but also TVC to some degree. The lake effect bands will also
be capable of snowfall rates of over an inch per hour, with 1 to 2
inches accumulation in NW lower and as much as 4 inches or so
nearer to PLN. The enhanced snows Friday evening are looking to
impact mainly TVC and MBL, and these snows could be rather
vigorous as well.

Westerly winds a tad gusty at times through Friday, going lighter
and more variable Friday evening.

&&

.MARINE...
Issued at 336 AM EST Fri Dec 8 2017

Low pressure just east of Superior will start to move east out of
the region this morning. Another (weak) low will advance into
western lower MI late tonight. These weaker system will keep
winds/waves from being especially ridiculous, but advisory-level
conditions will persist on most to all waters today. After a lull
for part of tonight, gustier n winds will emerge on Lake MI again
by Sat morning.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY until midnight EST tonight for MIZ008-
     019-021-022.
     WINTER WEATHER ADVISORY until noon EST today for MIZ016>018.
LH...SMALL CRAFT ADVISORY until 5 PM EST this afternoon for
     LHZ345>349.
LM...SMALL CRAFT ADVISORY until 5 PM EST this afternoon for LMZ323-
     341-342-344>346.
LS...SMALL CRAFT ADVISORY until 5 PM EST this afternoon for LSZ321-
     322.
&&

$$

NEAR TERM...JZ
SHORT TERM...MK
LONG TERM...MK
AVIATION...SMD
MARINE...JZ



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