Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 172027
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
327 PM EST Sat Nov 17 2018

.NEAR TERM...(Through Tonight)
Issued at 326 PM EST Sat Nov 17 2018

...Lake Effect Snow Showers Through Tonight...

High Impact Weather Potential: Minor impacts due to lingering lake
effect snows.

Broad troughing remains across eastern Canada down into the Great
Lakes, with relatively flat westerly flow from the Plains across the
Great Lakes and modest W-E upper jet streak centered over the
eastern lakes and draped across lower Michigan.

At the surface, respectable high pressure center (1039 MB) is
centered over the northern plains nosing eastward through the
Great Lakes with N/NW continuing to reinforce cold air into the
region. Tight thermal gradient through the Midwest/F-gen and modest
entrance region jet forcing continues to produce a narrow corridor
of precip stretching from far southern lower Michigan back into
the plains. Further north, disrupted and disorganized lake and
daytime heating induced "cellular" snow showers persist with
steeper low level lapse rates and H8 temps running neg 12C to neg
16C.

Tonight, daytime heating induced "cellular" snow showers will
come to a quick end heading into the evening leaving just
lingering lake effect snow showers to deal with. Continued drying
above the convective boundary layer, lowering inversions and
eventual subtle low level warming will lead to diminished lake
effect snow shower intensities for tonight as low level flow
gradually backs SW by Sunday morning. Still enough for
numerous->scattered snow showers through tonight that eventually
shift focus back up into the tip of the mitt/Straits region. Only
minor accumulations.

Otherwise, will likely see some degree of clearing well downwind
of the lakes. With weakening winds and some snow on the ground,
Wednesday nights/Thursday mornings low temperatures come to mind
when we had a number of single digit lows. So, I have lowered
forecast low temps for tonight to at or below MOS guidance temps,
particularly for the normally cold locations (GOV, HTL, etc). Will
see how it goes.


&&

.SHORT TERM...(Sunday through Tuesday)
Issued at 326 PM EST Sat Nov 17 2018

High Impact Weather Potential: Light snow possible Monday,
perhaps leading to slippery travel conditions across parts of
northern Michigan.

Pattern Synopsis: Broad/low amplitude troughing across much of the
CONUS will continue to dominate the upper level pattern through
early next week while ridging builds along the West Coast. Surface
high pressure nosing into the western Great Lakes this evening/
overnight will aid in bringing fairly tranquil conditions locally
through Sunday. However, early next week, another mid-level
shortwave races out of Alberta with an attendant weakly developing
surface reflection across the northern plains. This system will
spread snow chances back into northern Michigan during the day
Monday. Hot on its heels, another clipper system following a very
similar track as Monday`s system is expected to trek southeastward
out of Canada into the northern lakes Tuesday night into early
Wednesday...once again increasing snow chances across parts of the
forecast area.

Primary Forecast Concerns/Challenges: PoPs and snow amounts through
the forecast period.

High pressure encroaching from the west will bring much drier air
into the region for Sunday...evident by H8-H7 RH falling below 20%
across a good chunk of northern Michigan. Could still be a few
lingering scattered snow showers across the Tip of the Mitt given a
sufficient delta T environment and winds gradually backing to the
west/west-southwest. Otherwise, some peeks of sun and continued
chilly temperatures will bet he rule with highs topping out a couple
degrees on either side of 30.

Snow shower activity is expected to increase across far northern
Chippewa County Sunday night as a weak thermal gradient sags south
across southern Ontario/Lake Superior...ultimately providing the
focus for an uptick in moisture and synoptic support. As a result,
perhaps an inch or so of fresh powder across Whitefish Point/
Paradise...lesser amounts to the south and east toward the Soo.

By early Monday, attention shifts to an incoming shortwave and
developing area of low pressure across the upper Mississippi
Valley/northern Great Lakes. Guidance has slowly come into better
agreement over the past 24 hours yielding increased confidence in
light snow spreading over eastern upper and the Tip of the Mitt by
early Monday morning before gradually filling in across the M-72
corridor toward midday. Predominantly west-southwest low-level flow
leading to a bit if lake enhancement at times should lend itself to
the highest accumulations across southern Chip/Mack counties and
north of M-68 in the Tip of the Mitt where 1-3" is expected. 2
inches or less expected elsewhere across E. upper/northwest
lower...gradually tapering to less than an inch east of I-75/south
of M-32 before the snow diminishes across much of the area by Monday
evening.

Monday night into Tuesday expected to feature lingering lake induced
snow showers downwind of Lake Michigan and Lake Superior; however,
given a substantial loss of deep layer moisture and plummeting
inversion heights to less than 3kft...any snow showers should be
rather light and not add up to much.

By late Tuesday, another clipper system, similar to Monday`s
(although a bit deeper) is expected to be trekking into the northern
Great Lakes region. This system is expected to be crossing northern
Michigan Tuesday night into Wednesday with another round of
accumulating snow.

High temperatures Monday ranging from the mid 20s far north to near
freezing along and south of M-72...cooling several degrees for
Tuesday with high temperatures area-wide ranging from the the mid-
upper 20s.

&&

.LONG TERM...(Tuesday night through Saturday)
Issued at 326 PM EST Sat Nov 17 2018

High Impact Weather Potential: Minimal.

Tuesday night-Wednesday`s system mentioned above continues to move
across the area bringing accumulating snow to at least parts of
northern Michigan and also leaving a rather tight baroclinic zone
draped across northern Michigan. This gradient will retreat
northward as a warm front Thanksgiving Day with milder temperatures
expected by Friday into Saturday (highs in the mid 40s-50 for
some?).

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 104 PM EST Sat Nov 17 2018

N/NW flow Lake snow showers will continue to impact the terminal
sites this afternoon with the biggest impact at TVC. Snow showers
diminish in coverage tonight as low level flow backs to SW.
Remaining snow showers will get pushed into the tip of the mitt
and the PLN terminal site during the course of tonight before
diminishing completely on Sunday.


&&

.MARINE...
Issued at 326 PM EST Sat Nov 17 2018

Winds/waves diminish tonight, likely below small craft criteria.
However, stronger westerly winds develop again on Sunday into
Sunday night. Thus, will simply maintain the ongoing small craft
advisory as is.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until midnight EST Sunday night for LHZ347-
     348.
LM...SMALL CRAFT ADVISORY until midnight EST Sunday night for LMZ323-
     341-342-344>346.
LS...SMALL CRAFT ADVISORY until midnight EST Sunday night for LSZ321.
&&

$$

NEAR TERM...BA
SHORT TERM...MG
LONG TERM...MG
AVIATION...BA
MARINE...BA


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