Area Forecast Discussion
Issued by NWS Gaylord, MI

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231
FXUS63 KAPX 060537
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1237 AM EST Fri Dec 6 2019

.UPDATE...
Issued at 922 PM EST Thu Dec 5 2019

1012mb low pressure is in central WI, with an associated warm
front poking east into MBL-GOV-OSC. Small baroclinic leaf is noted
in satellite and radar ne of the surface low. Light snow is
falling near/north of an Empire-OSC line. This will progress
fairly quickly across northern MI over the next 6-8 hours, and by
daybreak only lake effect snows should be lingering in eastern
upper/nw lower/ne lower (nw to nnw flow).

Have boosted snow amounts a bit in parts of far northern lower MI,
just north of the surface warm front, where 850-700mb fgen is
maximized. Snowfall totals in the APN/Rogers area is now around 3
inches. Could pop an advisory there under some circumstances, but
for a nocturnal event, that seems unnecessary.

&&

.NEAR TERM...(Through Tonight)
Issued at 258 PM EST Thu Dec 5 2019

...The Basic 1-3" N MI Clipper...

High Impact Weather Potential...Minimal

Pattern Synopsis/Forecast...An Alberta Clipper system is dropping
into the Upper Great Lakes this evening. This is beginning to kick
off mainly flurries over N Lower and C Upper for the moment. The
main snow is showing up over the MN Arrowhead region and w Lake
Superior. Snow amounts and rates seem fairly light, and guidance
shows that a general 1-3" (Light amounts) is expected.

Primary Forecast Concerns...concerns are minimal as this system
looks to be behaving based on the models. Looking at the SREF plumes
from 09z this morning, ranges have been around the going forecast
for overnight into Friday. It is possible that a stray 4 to 5"
report isn`t out of the question, but the majority of this should
remain in the 1-3" range.

&&

.SHORT TERM...(Friday through Sunday)
Issued at 258 PM EST Thu Dec 5 2019

Short Term: (Friday through Saturday)

High Impact Weather Potential: Minimal

Subtle troughing and the associated weak clipper system will be
departing the region to the east to begin the period as surface high
pressure builds across the north-central CONUS underneath the ridge-
trough inflection point overhead. This high pressure system will
help funnel some colder air from Canada into the area before winds
switch to southerly later Saturday.

While snowfall associated with the weak clipper is expected to have
mainly vacated the forecast area Friday, lake effect snow across
portions of eastern upper and northern lower MI could last into the
afternoon hours. Steady northwest low to mid-level winds will last
for a narrow window during this time, but general lack of moisture
above 850mb and CAA/subsidence aloft will inhibit snowfall totals.
Additional accumulations near 1" with some locally higher amounts
within heavier bands are possible with this lake effect heading into
Friday night.

A weak wave/speed max has the potential to support more light
snowfall early Saturday morning across northern Michigan, but
accumulations are expected to remain very light due to near-surface
moisture being marginal at best. Otherwise, the aforementioned cold
air will drop lows into the teens on Saturday morning before warming
up throughout the weekend.

.LONG TERM...(Sunday night through Thursday)
Issued at 258 PM EST Thu Dec 5 2019

High Impact Weather: Potential winter storm early next week followed
by cold temps.

On Sunday, a trough across central Canada will develop a cyclone
near Hudson Bay. A cold front associated with this system is
expected to sweep down across southern Ontario and the northern
Great Lakes late Sunday into Monday. Temperatures warm ahead of this
and will support rain later Sunday into Monday before the arrival of
the next system, which is the main focus of this period. This
cyclone will develop in the southern Great Plains early Monday
before quickly moving/deepening along the previously mentioned
boundary into the southern Great Lakes. Rain, wintry mix, and snow
are all possible across northern Michigan with this system. However,
considerable uncertainty still exists regarding details and
locations of greatest impacts. Behind this system, very cold air
encompasses the area with temperatures in the single digits/teens
beginning Wednesday through the end of the week with wind chills
below zero possible.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1237 AM EST Fri Dec 6 2019

Low pressure will cross nrn Michigan through daybreak, with general
light snow in MVFR/IFR CIGS ending around 07Z at PLN/TVC, and at APN
around 10Z-11Z. In it`s wake, gusty NW winds and cold advection will
result in scattered light lake effect, mainly between TVC/PLN and
scraping by APN. Snow showers wane into the late afternoon/evening,
and there is also not enough confidence attm in showing any reduced
VSBYS right now, to do anything other than VCSH. CIGS today will
largely be MVFR, but will lift to VFR late today into this evening.
MVFR CIGS and some additional light snow showers may return by
daybreak Saturday at PLN.

&&

.MARINE...
Issued at 258 PM EST Thu Dec 5 2019

Tonight through Saturday...An Alberta clipper moves through the
Upper Great Lakes tonight, and the winds begin to ramp up after
06z/Fri. Some time around 09z, small craft gusts begin to creep up
Lake Michigan and across Lake Superior. This will lead to small
craft conditions on both of those lakes, with the winds not
increasing past small craft in the Straits or on Lake Huron until
after 12z/Fri. The clipper quickly moves east, and after 18z, winds
will begin to diminish on Lake Michigan first (by 21z/Fri), then
Whitefish Bay and the St. Mary`s River (by 00z/Sat) and then Lake
Huron (around 03z/Fri). Waves look to be subsiding around the same
times, so have set the times above as the end points for the small
craft headlines.

High pressure then sets in Friday night, but it too, moves quickly
east, and we get into the return flow. The pressure gradient then
tightens up as the next clipper system begins to drop into the Upper
Great Lakes for Saturday night into Sunday. There may be small craft
conditions on Lake Michigan by late Saturday afternoon.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY from 7 AM this morning to 10 PM EST this
     evening for LHZ345>349.
LM...SMALL CRAFT ADVISORY from 4 AM early this morning to 4 PM EST
     this afternoon for LMZ323-341-342-344>346.
LS...SMALL CRAFT ADVISORY from 7 AM this morning to 7 PM EST this
     evening for LSZ321-322.
&&

$$

UPDATE...JZ
NEAR TERM...JL
SHORT TERM...DJC
LONG TERM...DJC
AVIATION...SMD
MARINE...JL



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