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FXUS63 KAPX 181135
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
635 AM EST Fri Jan 18 2019

.NEAR TERM...(Tonight)
Issued at 156 AM EST Fri Jan 18 2019

High impact weather potential: Minimal.

Pattern synopsis and forecast:

Weak low pressure and a cold front with light synoptic snows have
crossed nrn Michigan early this morning, while another low pressure
and cold front was passing Hudson Bay and Ontario, driven by a
strong shortwave buried in sharp upper level troughing. Behind the
initial cold front that has rolled through, winds have shifted out
of the NW and has pulled in lake effect snow bands that were hanging
offshore in Lakes Michigan and Superior, into NW lower Michigan and
Chippewa county of eastern upper Michigan. Intensities were less
than impressive, as the deeper synoptic moisture have exited east
and inversion heights, per RUC soundings,

The aforementioned high pressure will sink down into the nrn Plains,
across srn Ontario, over into Quebec today, while low pressure
deepens around Oklahoma. This low pressure develops into quite the
storm system as it lifts into the lower Mississippi valley tonight,
due to fairly strong upper level divergence, DPVA and warm and moist
advection from the Gulf of Mexico. Significant snows develop on the
nrn and western flank of the low pressure tonight, with a small
chance of the far nrn edge of the system snow maybe making a run at
the M-55 corridor overnight tonight. Until then, nrn Michigan can
expect scattered light lake effect snow and flurries beginning in
the NW lake effect snowbelts, before transitioning to coming in off
Lake Huron, as winds veer around out of the NE. Despite increasing
cold advection which will bring H8 temperatures down to -15C south
to -21C north, the lake effect environment will be hostile than
anything else. Inversion heights will gradually lower from around
4000-45000 feet this morning to 3000-3500 feet tonight, with some
argument to be made that moisture in the BL is unimpressive. Am
thinking that scattered light lake effect snow showers and flurries
will just be fanning out from the NW snowbelts to north, before
coming in off Lake Huron to NE lower later tonight. Only minor snow
amounts.

Highs today will range from the teens in eastern upper, to the low
to mid 20s in the srn CWA. Lows tonight will be quite cold across
eastern upper, further away from thicker higher level clouds
expected in the srn CWA. Readings are expected in the negative
single digits and teens. Nrn lower will generally -5F to +5F.

&&

.SHORT TERM...(Saturday through Sunday)
Issued at 156 AM EST Fri Jan 18 2019

High Impact Weather Potential: Dangerously cold this weekend. Light
north flow lake effect Saturday night - Sunday.

Pattern Synopsis/Forecast: By Saturday morning, upper-level closed
low pressure is expected to be situated near Hudson Bay with potent
shortwave troughing encompassing much of the country's midsection.
Associated low pressure passing through the Mississippi/Ohio valleys
Friday night into Saturday will keep its impacts largely centered
well to our south as the primary focus for the weekend locally
becomes centered around the coldest air so far this season arriving
Saturday through Monday.

Primary Forecast Concerns/Challenges: PoPs early Saturday & again in
north flow snow belts Saturday night-Sunday, along with bitterly
cold temperatures/wind chills.

While the primary impacts will be felt well to our south with Friday
night/early Saturday's low pressure system, wouldn't be surprised to
have snow showers ongoing at the start of the period Saturday
morning, mainly south of M-72 and most frequent along and south of M-
55. With respect to accumulation, perhaps up to an inch in spots
near Saginaw Bay, although the majority of the area will be hard-
pressed to even realize that.

Attention quickly turns to incoming cold air drawn in behind the
departing storm system as it shifts toward the East Coast. H8 temps
progged to fall from near -15 C early Saturday to -26 to -22 C by
Saturday night. As a result, high temperatures Saturday struggling
to reach much more than the upper single across eastern upper and
the interior highlands of northern lower to low-mid teens in Great
Lakes collar counties. Saturday night, low temps fall below zero for
many away from the Great Lakes and across the U.P. with wind chill
readings near -30 F north of the bridge and ranging from -20 to
-10 F over northern lower.

Even colder Sunday with highs in the single digits above zero for
most. Sunday night lows in the negative teens...to perhaps some -20s
in the typically colder locations. Wind chills again dangerously
cold...ranging from -30 to -20 F area-wide.

With respect to light north flow lake effect snow showers, the
expectation is for snow shower activity to be ongoing over Lake
Michigan and the central UP during the day Saturday given a north-
northeasterly wind before winds gradually back more northerly
Saturday evening, allowing light snow showers to push inland and
continue off/on through Sunday. Most numerous activity expected near
and west of Grand Traverse Bay and across far northern Chippewa/
northwestern Mackinac counties. However, given such cold
temperatures, small flake size and anemic moisture above a 4-5 kft
inversion, expecting accumulations to be rather light...generally
under an inch.

.LONG TERM...(Sunday night through Thursday)
Issued at 156 AM EST Fri Jan 18 2019

High Impact Weather Potential: Very cold temperatures continue
Monday - Monday night. Potential for an impactful winter storm
Tuesday - Wednesday, although confidence is low.

Cold temperatures continue Monday with high temps in the upper single
digits to mid-teens across the forecast area. Overnight lows Monday
again dropping to near zero for many. Focus then transitions to
developing low pressure lee of the Rockies during the day Monday
before trekking eastward toward the Mississippi Valley and
eventually the Great Lakes by midweek. Uncertainty remains high with
regards to timing, track and resultant precip types/accumulations,
but the potential is certainly there for an impactful winter storm
by Tuesday - Wednesday of next week.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 634 AM EST Fri Jan 18 2019

Nrn Michigan will be locked between high pressure to our north and a
developing storm system to our south over the TAF period, with
veering flow from NW to NE. Only scattered light lake effect snow
and flurries are expected at times, with very minor snow amounts.
CIGS are expected to be MVFR/low end VFR for much of the TAF period.
Wind speeds will generally be 10kts or less, with maybe just a
little gustiness this afternoon.

&&

.MARINE...
Issued at 156 AM EST Fri Jan 18 2019

High pressure will extend from central Canada into Ontario and
Quebec today and into the weekend, while a strong storm system
evolves in the srn Plains, and deepens as it tracks to the Atlantic
coast. There will be various times for low end advisory wind speeds
today through this weekend, as well as scattered light lake effect
snow and flurries.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 11 PM EST this evening for LHZ347-348.
SMALL CRAFT ADVISORY until 4 PM EST this afternoon for LHZ345-
346.
LM...SMALL CRAFT ADVISORY until 4 PM EST this afternoon for LMZ342-
344.
&&

$$

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