National Weather Service - Area Forecast Discussion

237
FXUS63 KAPX 172311
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
611 PM EST Thu Jan 17 2019

.NEAR TERM...(Through Tonight)
Issued at 244 PM EST Thu Jan 17 2019

...Light snow accumulations expected into tonight...

High impact weather potential: Minimal. Minor snow accumulations to
bring potential for some slick travel overnight.

Pattern synopsis/forecast: Broad troughing extends from the northern
Plains through the Great Lakes region early this afternoon. Couple
shortwaves embedded within this longer wave trough, one digging into
the northern Ohio Valley, with a secondary less defined wave
dropping southeast into the northern Mississippi Valley. Most active
weather tied to the former, with a developing surface trough/cold
front and area of light snow associated with the latter across the
western Great Lakes. Maturing southwest flow between this
approaching surface trough and quick departure of East Coast high
pressure starting to spread some light lake-driven snow showers into
eastern upper Michigan. Otherwise, a pretty quiet mid-January day
across the Northwoods so far, with temperatures pushing up into the
20s under partly to mostly cloudy skies.

While main corridor of deeper moisture safely slides by to our south
later this afternoon and evening, approach and passage of that
northern wave and attendant cold front will bring a round of mostly
light lake enhanced snows to much of the area later today through
this evening.

Primary forecast concerns/challenges: Evolution of lake enhanced
snows and expected snow amounts.

Details: While passing shortwave and cold front will have limited
synoptic forcing and moisture to work with, what they do have will
work over a still somewhat favorable over-water thermal environment,
helping drive an expanding area of snow into the region later this
afternoon and evening. With that said, lake snow parameters far from
impressive, with convective depths only topping out a bit above
5.5kft and omega that remains disjointed in the favored dendritic
growth layer. Passage of cold front this evening rapidly swings
southwest winds to northwest, further negating any organized banding
potential. Synoptic moisture contribution exits quickly with passage
of wave, suggesting that despite good northwest flow cold air
advection overnight, additional lake snow showers should also remain
light and disorganized. Upshot to the above, expect snow
accumulations to remain light, topping out at about 2 inches or so,
with the "heaviest" falling across far northwest lower Michigan and
the Lake Superior snow belts of Chippewa county. No headlines
required, covering any transient pockets of heavier snows with
special weather statements.

&&

.SHORT TERM...(Friday through Sunday)
Issued at 244 PM EST Thu Jan 17 2019

...Coldest air of the season this weekend...

High Impact Weather Potential...Bitterly cold arrives this weekend.

Pattern Synopsis/Forecast...The upper low over Hudson Bay rotates
very cold air into the Great Lakes this weekend. The east coast
storm will also help to filter the cold air into Michigan. 850mb
temperatures drop to around -25C Saturday night and Sunday.
Northerly low level winds will keep lake effect snow confined
mainly to the lake shorelines.

Primary Forecast Concerns...Dangerously cold wind chills are
expected, especially in eastern Upper Michigan, Saturday morning and
Sunday morning. Temperatures will feel like -30F across the eastern
UP and in the -20s at times across interior northern Lower. High
temperatures Sunday afternoon may not reach zero across the normally
cold parts of the area.

.LONG TERM...(Sunday night through Thursday)
Issued at 244 PM EST Thu Jan 17 2019

High impact weather potential: Very cold temperatures Monday
morning. Potential for winter storm to affect the area Tuesday and
Wednesday.

Pattern Synopsis/Forecast: Upper low just north of the Great Lakes
moves off to the east coast Monday. Next trough moves through
Wednesday. At the surface, high pressure makes a brief appearance
Monday before the a potent storm approaches Tuesday. The storm right
now is forecast to track through the Missouri Valley Tuesday and
then through the eastern Great Lakes Wednesday and to the east coast
Thursday. Meanwhile, very cold air continues to build up across
central Canada and starts to push southeast Thursday.

Primary Forecast Concerns...Monday morning, northern MI residents
will wake to temperatures well below zero. Readings are expected to
be 20 to 25 degrees below normal. Next, the storm system moving out
of the Plains is forecast to track through northern Ohio or southern
Michigan. Snow is expected to move into the region Tuesday. A
further north track would have an even greater impact our region
with a descent snow storm late Tuesday and Wednesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 611 PM EST Thu Jan 17 2019

An area of lake enhanced snow will impact Northern Lower Michigan
tonight...especially during the evening hours...dropping
conditions to MVFR/IFR. Most persistent snowfall and lowest
cigs/vsbys will be across NW Lower Michigan thanks to lake
enhancement. Snow showers will diminish on Friday...with mainly
VFR conditions expected to return. Light/variable winds will
become NW later tonight and will then strengthen to 15 to 25 kts
on Friday.

&&

.MARINE...
Issued at 244 PM EST Thu Jan 17 2019

Southwest winds will become northwest and increase in speed
tonight and Friday as a cold front crosses the area. Wind gusts will
likely approach or exceed small craft advisory levels across at
least some of our nearshore waters by later tonight and Friday.
Winds will subside a bit Friday night before increasing again to
start the weekend.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY from 1 AM to 11 PM EST Friday for LHZ347-
     348.
LM...SMALL CRAFT ADVISORY from 1 AM to 4 PM EST Friday for LMZ323-342-
     344>346.
&&

$$

NEAR TERM...MB
SHORT TERM...KF
LONG TERM...KF
AVIATION...MR
MARINE...MB

NWS APX Office Area Forecast Discussion