Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 140806

Area Forecast Discussion
National Weather Service Gaylord MI
306 AM EST Sat Dec 14 2019

.NEAR TERM...(Today through Tonight)
Issued at 255 AM EST Sat Dec 14 2019

Impactful weather: Areas of drizzle, freezing drizzle and light fog
changing to light lake effect snow showers tonight, with minimal

Pattern synopsis and forecast:

Weak low pressure and a slowly eastward-moving cold front was laid
out across the western Great Lakes still early this morning,
underneath upper level troughing with several weak perturbations in
the flow. This has resulted in areas of drizzle, freezing drizzle
and light fog in nrn Michigan, with still deep low level moisture
not even flirting with -10C for ice introduction. Reflectivities on
regional radars back to the west were falling as snow, where the low
level air mass was colder. Even colder air was noticed further
upstream, where the pressure gradient was also tightening behind the
weak sfc low, and winds were becoming gusty out of the NW.

The weak sfc low and cold front will gradually move across nrn
Michigan today, allowing for a decent chance at seeing at least a
little bit of drizzle/freezing drizzle. Fcst soundings do not show
the low level moist air getting into a cold enough air mass for ice
introduction, and a changeover to lake effect snow showers until
nightfall/this evening. The snow showers may get a boost this
evening, at least to a small degree, as one of the better
perturbations in the flow aloft, and it`s associated bump up in
atmospheric moisture, sweep across nrn lower Michigan. Inversion
heights bump up to 6kft or so with this wave, before dropping to
less than 5kft after it`s passing. However, continued CAA will
likely allow the light lake effect to persist through the night in
the NW flow regimes, despite some atmospheric drying. Also, expect
those gusty NW winds to kick in tonight.

High temperatures will mostly be in the low to mid 30s again, with
lows getting down in the 10F to 20F range most areas tonight.


.SHORT TERM...(Sunday through Monday)
Issued at 255 AM EST Sat Dec 14 2019

High Impact Weather Potential...Minimal.

Pattern Synopsis/Forecast...Sunday, NW LES flow backs to the West
and the amounts of snow begin to diminish as the atmosphere dries
out. However, the snow doesn`t necessarily end, as the 850 mb
temperatures remain around or colder than -10C over N Lake Michigan.
This continues the LES snow, but it should remain minor as the snow
looks light from the less than 50% rh in the 850-700 mb layer and
the still moving direction. This remains through the night. Monday,
the 850 mb temperatures warm enough that the LES looks to stop.
However, the southern system is now south of the Ohio river on the
GFs and ECMWF. The NAM and SREF (03z)still shows the sfc low far
enough north that the precipitation moves into N Lower. The pops are
still on the low side, never getting above 50%. However, Monday
night, a northern branch feature begins to push into the region and
with cold 850 mb temperatures, so that the LES machine begins to
start back up. with light to moderate snow possible.

Primary Forecast Concerns...The sfc low that is near the Ohio River,
has come in farther south on the GFS and ECMWF than previous runs,
with the NAM/SREF still holding onto the idea that it will be
farther north. With the better idea of the GFS and ECMWF it is
possible that we don`t get any precipitation, until the northern
branch feature drops into the Upper Great Lakes, and begins the LES
with the sub -10c 850 mb air. If the Moisture in the layer (850-700
mb) continues above 70%, then some of these bands could be moderate,
instead of light.

.LONG TERM...(Monday night through Friday)
Issued at 255 AM EST Sat Dec 14 2019

High Impact Weather Potential...Minimal.

Extended (Tuesday through Friday)...Tuesday and Wednesday continue
the LES, although, the snow looks to diminishes on Wednesday as a
ridge moves through the forecast area. On the backside of the ridge
overnight, a warm front moves through the region into Wednesday
night and out of the region by Thursday morning. High pressure then
builds into the region on Thursday and lasts through Friday on the
ECMWF. The GFS, however, has an occluded system with the stacked low
over Lake Superior, by Friday evening. This would bring light snow
over the region through Saturday morning.


.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1205 AM EST Sat Dec 14 2019

Weak low pressure and a cold front will cross nrn Michigan today,
leading potentially more light fog and periods of drizzle. Cold
advection will turn any precipitation over to snow around nightfall
in NW lower, with lesser chances at APN. NW winds will also be
turning more brisk and gusty tonight, as the pressure gradient
tightens. The lake effect is expected to be light, with minimal
accumulations of around a half inch tonight in NW lower. Liquid to
snow ratios will fall from around 15:1-16:1 this evening to 18:1-
20:1 late in the TAF period.


Issued at 255 AM EST Sat Dec 14 2019

Weak low pressure and a cold front will cross the region today,
resulting in some potential spotty drizzle, in weak winds. Cold
advection sets in tonight, with the pressure gradient tightening,
and NW winds ramping up into advisory speeds and continuing into
Sunday. Winds back around more southerly later Sunday through Sunday
night, and weaken, as higher pressure arrives.


LH...SMALL CRAFT ADVISORY from 5 PM this afternoon to 3 PM EST Sunday
     for LHZ347>349.
     SMALL CRAFT ADVISORY from 5 PM this afternoon to 5 AM EST Sunday
     for LHZ345-346.
LM...SMALL CRAFT ADVISORY from 5 PM this afternoon to 11 AM EST
     Sunday for LMZ323-342-344>346.
     SMALL CRAFT ADVISORY from 5 PM this afternoon to 5 AM EST Sunday
     for LMZ341.
LS...SMALL CRAFT ADVISORY from 10 PM this evening to 5 AM EST Sunday
     for LSZ322.
     SMALL CRAFT ADVISORY from 5 PM this afternoon to 11 AM EST
     Sunday for LSZ321.


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