Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 241044

Area Forecast Discussion
National Weather Service Gaylord MI
644 AM EDT Tue Oct 24 2017

.NEAR TERM...(Today through Tonight)
Issued at 348 AM EDT Tue Oct 24 2017

High impact weather potential: Heavy rain and very windy.

Pattern synopsis and forecast:

Early this morning, quite dynamic storm system out there with deep
998mb sfc low over APN, buried underneath deep upper troughing
engulfing the western Great Lakes. Forcing was impressive, with
upper divergence, WAA within clear trowal signature, DPVA from
northward-wrapping shortwave through nrn Michigan and FGEN
deformation. When combined with deep moisture (PWATS near an inch),
rainfall has been impressive with much of the region seeing 2-4" of
rain thus far. No reports of flooding however, likely due to the
sandy nature of the soils in much of nrn Michigan. Rainfall has
continued to come down hard outside of a temporary reprieve in
portions of NE lower and eastern upper, and will thus leave the
flood watch in place. As with these intense/deep systems, there has
been a lot of wind to deal with, several reports of 35 to 45 mph
gusts have been seen at times across mainly eastern upper and NW
lower, where winds have come in off the Great Lakes where conditions
were unstable. Winds have relatively weakened in NE lower of late as
the sfc low has moved in overhead.

The sfc low will settle in over eastern upper through the day before
starting to work eastward through tonight. The WAA/trowal signature,
along with deformation and FGEN will set up across the western half
of the CWA, and when combined with sufficiently cold H8 temps, lake
enhancements will be ongoing as well. Heaviest rains will be in the
morning while forcing is strongest. As the system starts heading
east, cold advection results in even greater instability over the
lakes, while the western flank of the pressure gradient remains
tight. Gotta believe that 40 to 50 mph gusts will be possible at
times through this evening across the NW lower coastal counties, as
well as Cheboygan/Chippewa and Presque Isle areas bordering Lake
Huron. Have thus added them to the wind advisory. All areas to see
additional rain through the night with the most, an inch or greater,
occurring in the NW flow lake effect areas of NW lower. In addition,
still could see some higher terrain snowfall sneaking in late
tonight as H8 air cools to -4C and sfc based warm layer sneaks to
below 1200 feet. No accumulation expected at this time.


.SHORT TERM...(Wednesday through Thursday)
Issued at 348 AM EDT Tue Oct 24 2017

...Rain and possibly snow showers ending...

Wrap around moisture along with lake enhancement will continue
scattered to numerous rain and possibly snow showers. Looking at
model soundings, it looks increasingly favorable for a mix with or
possible change over to all snow Wednesday morning as cold air
advection continues to drop 850 mb temperatures whittling down the
melting layer. Although models don`t seem to think so still believe
that some spots, mainly the higher terrain of northwest lower and
interior eastern upper could see a wet coating of snow. Time will
tell on that one. Drier air/subsidence should put an end to any
remaining lake processes Wednesday evening. Short lived ridging at
the surface and aloft Wednesday night will be followed by decent
warm advection leading to increasing clouds Thursday from an Alberta
Clipper dropping southeast toward the region. Temperatures Wednesday
nearly steady in the lower and middle 40s at best. Lows Wednesday
night in the upper 20s to middle 30s. Highs Thursday in the upper
40s to lower 50s.

.LONG TERM...(Thursday night through Monday)
Issued at 348 AM EDT Tue Oct 24 2017

A slow moving Alberta Clipper and upper low will bring showery
weather to the region through the upcoming weekend. It may be cold
enough for rain showers to mix with or change over to all snow
showers (especially at night). Extended models vary on what happens
early next week...possible break or another low pressure system may
come barreling in. Temperatures look a few degrees below average for
late October.


.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 638 AM EDT Tue Oct 24 2017

Strong deep low pressure will settle into eastern upper today
before slowly tracking east tonight. Deep moisture and lake
enhanced rains will pound the NW lower airports, while additional
rains make it back into APN. A tight pressure gradient across the
region will result in very gusty winds that will continue to veer
more of of the west and northwest through the day. Rainfall will
begin to taper off in intensity later today and through this
evening. Widespread MVFR/IFR cigs and reduced VSBYS at times will
be common. Winds will also diminish some through tonight, although
it will remain gusty.


Issued at 348 AM EDT Tue Oct 24 2017

Gale force winds will be common at times across all nearshore waters
through tonight, as a strong low pressure system remains over nrn
Michigan, slowly departing tonight. Overlake instability is helping
tap stronger winds aloft, and would not be surprised to see a few
storm force gusts as well, into this evening. Winds will gradually
weaken late tonight through Wednesday, as relatively higher pressure
moves in. Rain will also be common across the Great Lakes,
especially Lake Michigan and Superior, where lake effect will
add to system rains.


MI...FLOOD WATCH until noon EDT today for MIZ008-015>036-041-042.
     WIND ADVISORY until 3 AM EDT Wednesday for MIZ008-016>021-025-
LH...GALE WARNING until 6 AM EDT Wednesday for LHZ345>349.
LM...GALE WARNING until 6 AM EDT Wednesday for LMZ323-341-342-344>346.
LS...GALE WARNING until 6 AM EDT Wednesday for LSZ321-322.


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