Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 172342
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
642 PM EST Fri Nov 17 2017

.UPDATE...
Issued at 623 PM EST Fri Nov 17 2017

Quick update to grids/HWO, and an SPS has been issued, for
potential period of brief freezing rain in n central lower. Ob at
GLR as precip gets underway is 33/27, favorable for wet bulbing
just below 32f before better warm advection gets going at the
surface. Arrival of darkness and loss of diurnal heating will
aid potential for fzra. Do not expect this potential to persist
for too long before warmer air (such as it is) wins out.

&&

.NEAR TERM...(Tonight through Saturday)
Issued at 351 PM EST Fri Nov 17 2017

...Mostly rain but perhaps a little snow...

Models continue to struggle with the details of the incoming storm
system set to move in tonight into Saturday. The problem appears to
be that competing areas of energy moving through the flow don`t
allow for a singular deepening system (at least until its off to our
east).

Tonight...The main area of precipitation is still set to swing
through late this afternoon into the first half of tonight. Looking
at model soundings/cross sections this should be mainly in the form
of rain across northern lower with all reporting stations finally
above freezing (though can not totally rule out wet bulbing down to
freezing again leading to a brief period of freezing rain).
Meanwhile across eastern upper, a mix with or even a period of snow
is likely with an inch or two of wet snow accumulation possible. QPF
from the rain should average about a half inch.

Saturday...Models are all over the place on the details with the
ECMWF now joining the drier NAM model. Meanwhile the GFS and to a
lesser extent the Canadian model bring a period of decent
precipitation across at least northern lower from mid morning until
early afternoon. Will side with the drier solution. Any
precipitation should start mainly in the form of rain...but cooler
air just ahead of the trailing drier air/subsidence could change the
rain over to a period of snow around noon time (especially over the
higher terrain). Still don`t anticipate any major snow accumulations
which should remain under an inch. Be cognizant of the potential for
icy spots to develop as temperatures slowly fall toward the freezing
mark during the afternoon.

&&

.SHORT TERM...(Saturday night through Monday)
Issued at 351 PM EST Fri Nov 17 2017

...Slick travel potential Saturday night...

High Impact Weather Potential:  Gusty winds Saturday
afternoon/night. Potential for flash freezing on area roads late
Saturday afternoon/night as wet roads from Saturday rain may freeze
up as temperatures fall Saturday evening. Potential for
drizzle/freezing drizzle late Saturday night/Early Sunday morning.

Pattern Forecast:  Progressive pattern remains through next week.
Low pressure will continue to lift through SE MI Saturday night with
high pressure following quickly behind. Broad high pressure spanning
from the Plains into southern Canada will be flattened a bit by
quick moving shortwave, which will help to bring in a brief shot of
cold air and give some assistance to lake effect development behind
the departing low. The cold intrusion will be short lived, as the
ridge axis from the western high folds into the region, beginning
warm advection early Monday morning. This ridging will remain in
place through the short term, with the next clipper in line over NW
Ontario.

Primary Forecast Concerns/Challenges: Timing for further rain to
snow transitions overnight. Possibility of drizzle/freezing
drizzle as synoptic moisture strips out Saturday/Sunday, before
lake effect starts. Gusty winds continue Sunday.

Precipitation will continue Saturday day on the NW side of the
departing low pressure. Temperature profiles remain right on the
edge for snow vs. rain, but will likely be snow across the majority
of the forecast area. Winds will remain gusty into Sunday evening,
as the pressure gradient relaxes a bit with the high pressure moving
in. A quick moving clipper along the northern periphery of the
western ridging will delay the height rises into the area a bit,
bringing a brief shot of cold air Sunday. There will be enough
instability to kick off lake effect snow, but varying wind direction
and a pretty dry airmass will likely keep accumulations from the
lake effect minor. Still have some concerns for drizzle potential
during the break between the synoptic system and lake effect. Model
soundings continue to show a period of saturation not quite reaching
-10C. This could bring a brief window for some drizzle/freezing
drizzle late Saturday night into early Sunday morning. This could be
a secondary concern; however, as wet roads from rain early in the
day may become slick anyway as temperatures drop below freezing.
Temperatures will continue their roller coaster ride, with early
week temperatures getting near the 40s again. Another cold shot will
arrive mid-week.

.LONG TERM...(Monday night through Friday)
Issued at 351 PM EST Fri Nov 17 2017

High Impact Weather Potential...

Wave train will continue through the extended period, as broad
ridging builds over the western U.S. and shortwaves move along the
baroclinic zone. Gusty winds will be likely again on Tuesday as the
first clipper pushes in, tightening the pressure gradient once
again. This will bring another round of cold air and lake effect
chances. Another clipper could arrive over the weekend. Details are
still a bit murky for Thanksgiving as far as precip chances and
type.

&&

.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 642 PM EST Fri Nov 17 2017

Worsening flying conditions tonight into Sat morning.

Rain is moving into northern lower MI, ahead of a cold front
advancing into WI and western Superior. Rain will become less
widespread again overnight. However, cigs will steadily lower, and
vsbys will respond as well. We are currently VFR, but eventually
IFR to perhaps LIFR cigs will be realized late tonight into the
start of the day Saturday. Cigs will eventually improve to MVFR.

Ongoing se winds (gusty at times) will lighten tonight. A gusty nw
wind develops Sat afternoon. LLWS for part of this evening, with
strong southerlies just off the surface.

&&

.MARINE...
Issued at 351 PM EST Fri Nov 17 2017

Gusty southeast to south winds with widespread small craft
advisory conditions continue through much of tonight. Winds may
temporarily decrease late tonight before increasing out of the
north Saturday as low pressure passes by to our south. Northwest
winds will then remain gusty through Sunday so have extended the
small craft advisories through that time. Still an outside chance
for a few gale force gusts Saturday afternoon and evening on Lake
Michigan.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 7 PM EST Sunday for LHZ345>349.
LM...SMALL CRAFT ADVISORY until 7 PM EST Sunday for LMZ323-341-342-
     344>346.
LS...SMALL CRAFT ADVISORY until 7 PM EST Sunday for LSZ321-322.
&&

$$

UPDATE...JZ
NEAR TERM...AS
SHORT TERM...AM
LONG TERM...AM
AVIATION...JZ
MARINE...AS



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