Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 152323

Area Forecast Discussion
National Weather Service Gaylord MI
723 PM EDT Sun Apr 15 2018

.NEAR TERM...(Tonight through Monday)
Issued at 334 PM EDT Sun Apr 15 2018

...More messy weather tonight and Monday...

High impact weather potential: Plenty! Additional snow and sleet
accumulations expected right through Monday for parts of the area.
Freezing rain/drizzle threat also lingers.

Pattern synopsis/forecast: Upper level system responsible for what
has been, for at least parts of our area, a historic late season
winter storm continues to ever so slowly pivot east across the lower
Lakes this afternoon. Surface low response not nearly as impressive
as its mid level parent, although slow deepening of this low to near
1000mb pretty respectable in its own right. Deep Gulf of Mexico
moisture feed directed right into our area this afternoon. Elevated
warm layer that shrinks in depth as one goes north, coupled with a
surface-based below freezing layer that shrinks as one goes south,
and we are getting a plethora of precipitation types across the
area. Mostly snow and sleet north of the big bridge, with the rare
prolonged sleet fest for the north half of northern lower. Freezing
rain becoming more the dominate precip type further south as that
surface based sub-freezing layer shrinks.

Slow moving upper level storm will remain just that...slow it works its way across the lower Lakes tonight and
Monday. Surface low will also take its time working north, reaching
vicinity northern Lake Huron by Monday evening. Moist conveyor belt
will work around the periphery of the upper level wave, focusing
further north with time. Unseasonably cold thermal profiles will
continue to support a wintry mix of weather types right through

Primary forecast concerns/challenges: A lot, although primary focus
remains on snow/sleet/freezing rain amounts and attendant headline

Details: Conveyor belt of moisture will continue to steadily rotate
north for the remainder of this afternoon and evening. Precipitation
types will largely remain as they are, but would expect a northward
expansion of freezing rain with time, as well as some areas down
near M-55 changing over to plain liquid. Additional ice
accumulations into early this evening expected to remain below a
quarter of an inch, with several inches of snow/sleet as one goes
north into eastern upper Michigan. Aggressive dry slot works north
into much of the area this evening and through the early overnight.
Plenty of low level moisture will linger, with soundings definitely
supporting a drizzle/freezing drizzle scenario, especially over
northern lower Michigan. Not confident on deep moisture completely
scouring out for areas north of the bridge. Recent trends now are
much more robust reorganizing upper level low pressure directly
overhead later tonight and Monday. This would allow deep Atlantic
moisture to rotate back west into at least the northern half of our
area toward Monday morning. A noticeable upward trend on nearly all
guidance forecasted precipitation amounts through Monday, with some
now suggesting upwards of a half to three quarters of an inch along
and north of M-32. Cooling thermal profiles support a steady
changeover back to snow early Monday, suggesting several inches of
new snow is possible. However, lessoned learned from past similar
events is guidance is often too aggressive with western extent of
Atlantic moisture. Will tone down amounts some, but still have an
additional 2 to 4 inches of snow along and north of that M-32
corridor late tonight through Monday. Remaining downright cold
Monday, this despite some gradual modification of the airmass, with
highs ranging through the lower and middle 30s.

Headline management: Complicated one for sure. While heaviest precip
will exit northern lower rather quickly early this evening,
lingering light freezing drizzle and impacts from todays
sleet/freezing rain will make for some rather dicey driving
conditions. Per coordination with Detroit and Grand Rapids, will
extend those warning along/south of M-72 right through the evening.
Even more complicated to the north with that upward trend in
snowfall Monday. While winds will subside some, ongoing very
hazardous driving conditions will remain, with several secondary
roads along the M-32 corridor still severely impacted by the recent
heavy snow and sleet. Per coordination with Marquette, have decided
the best course of action will be to extend all warning along and
north of M-32 through Monday.


.SHORT TERM...(Monday night through Wednesday)
Issued at 334 PM EDT Sun Apr 15 2018

...Historic winter storm finally comes to an end...

High impact weather potential: For a change...not much.

Pattern synopsis/forecast: And so it ends, as slow moving and
extremely high impact winter storm finally moving east of the
region. Brief, but highly welcomed reprieve to follow as northern
Conus pattern become a touch more progressive. Unfortunately, that
same progressive pattern looks to bring the next system into at
least portions of our area later Wednesday. Fortunately, this system
will have a lot less moisture and a much more modified airmass to
work with.

Primary forecast concerns/challenges: Lingering snow shower trends
Monday night/early Tuesday as well as addressing that next rain/snow
shower potential later Wednesday.

Details: While high impact portion of the storm will have exited,
plenty of lingering low level moisture will continue to produce snow
showers across the area Monday night, ending during the day Tuesday.
While thermal profiles look a bit too "mild" for any lake
contribution, moist low levels and persistent upslope enhancement
should focus the greatest snow shower coverage into northwest lower
lower Michigan, where an additional inch or two of snow looks more
than reasonable. Lingering snow showers expected to largely come to
an end by Tuesday afternoon, although plenty of snow cover and
afternoon temperatures remaining in the 30s will make it look and
feel much more like winter than the middle of spring. Dry and chilly
conditions Tuesday night gives way to our next system on Wednesday.
As mentioned earlier, much less moisture for this system to work
with, and expected arrival of better forcing during the afternoon
should allow low level thermal profiles to modify considerably,
supporting primarily light rain. Despite this "warming", afternoon
readings in the lower and middle 40s will still be plenty below
normal for this time of year.

.LONG TERM...(Wednesday night through Sunday)
Issued at 334 PM EDT Sun Apr 15 2018

...Temperatures finally moderating to normal...

Pattern Synopsis/Forecast...The extended forecast will begin with a
low pressure system skirting the southern Great Lakes region,
producing some rain and snow Wednesday night into
Thursday...accumulations appear to be light at this time. High
pressure centered over Hudson Bay and associated dry air begins to
build into the forecast period and looks to dominate our weather
through the weekend and perhaps even into the beginning of the next
work week. This will begin moderating the temperatures to normal for
this time of the year...possibly reaching 50 in some locales
beginning Friday and warming a few degrees each day into the weekend.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 711 PM EDT Sun Apr 15 2018

Large area of low pressure will continue to slowly work eastward
through the Great Lakes over the next 24 to 36 hours. Just
scattered precipitation at MBL/TVC this evening, with
precipitation more widespread at APN/PLN.  Still a variety of
precipitation types tonight with light rain, snow, freezing rain
and sleet possible. As colder air wraps in from the northwest late
tonight into Monday, precipitation will transition back toward
all snow. Cigs/Vsbys ranging from IFR to MVFR tonight, with IFR
conditions more likely late tonight into Monday as more widespread
precipitation once again develops across the area. Winds remaining
gusty from the northeast tonight, with the highest gusts gradually
diminishing. Winds will shift to the north/northwest late tonight
into Monday.


Issued at 334 PM EDT Sun Apr 15 2018


Very gusty northeast winds, especially across Lake Huron, will
slowly subside overnight as the pressure gradient relaxes some.
Inherited storm warnings have been downgraded to gales on Lake
Huron, extending through tonight. Lingering gales this evening
across portions of northern Lake Michigan, with small craft
advisories elsewhere. Small craft advisory conditions look to
continue right through Tuesday on most nearshore waters.


MI...WINTER STORM WARNING until 2 AM EDT Monday for MIZ025>036-041-
     WINTER STORM WARNING until 8 PM EDT Monday for MIZ008-015>024.
LH...GALE WARNING until 6 AM EDT Monday for LHZ345>349.
LM...SMALL CRAFT ADVISORY until 6 AM EDT Monday for LMZ323-344>346.
     GALE WARNING until midnight EDT tonight for LMZ341-342.
LS...SMALL CRAFT ADVISORY until 6 AM EDT Monday for LSZ321-322.


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