Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 212101
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
401 PM EST Sun Jan 21 2018

.NEAR TERM...(Tonight through Monday)
Issued at 355 PM EST Sun Jan 21 2018

High impact weather potential: Accumulating snowfall and ice
resulting in potentially very hazardous travel conditions.

Pattern synopsis and forecast:

Another pretty quiet period of weather today. The stratus and fog is
just about completely mixed out along the M-55 corridor, while the
rest of nrn Michigan continues the same theme as the last few days,
of higher level cloud passing overhead. This was due to weak
vorticity ejecting out of a closed upper low in eastern Colorado.
Deeper Gulf of Mexico moisture was feeding into the associated sfc
low which was deepening in Kansas. A warm front extended eastward
through Illinois and Indiana, with additional inverted troughing
through the western Great Lakes. A light southerly wind has advected
slightly higher sfc dew points and temperatures up into the region.
Readings were in the upper half of the 30s to middle 40s (except
where the stratus and fog remain where temperatures were still
lingering in the lower to middle 30s).

There is good consensus on the sfc low lifting NE and settling into
the WI/IL/IA border by daybreak Monday, with the warm front settling
into the srn half of Lake Michigan and along the M-55 corridor by
Monday afternoon. The Gulf moisture feed will increase through
tonight. with a band of showers and thunderstorms developing and
crossing the lower half of the Mississippi valley. This may rob nrn
Michigan of moisture, and the signal is there in the data. QPF
expected to be less, but a half inch or more is likely to spit out
over nrn Michigan through Monday, as forcing ramps up with many of
the big names. DPVA, WAA, upper divergence and low level
convergence. The big question is how will the thermal regime set up,
driving precipitation types. At the sfc, the trend is warmer, which
is certainly plausible considering we have been warmer than guidance
the last couple of night with that higher cloud somewhat blanketing
us. Also the higher dew points is certainly an indicator. This will
to some degree limit the amount of time for sfc temperatures below
zero, thus lessening the time for icing before sfc temperature rise
through the day Monday from south to north to above freezing up to
the M-68 corridor of nrn lower. The elevated warm nose from the WAA
will wrap around as far north as maybe the Straits, resulting in the
wintry mix of snow, sleet and freezing rain for all of nrn lower.
All of this action may also be preceded by a little drizzle and
freezing drizzle late tonight.

After putting all the data together, temperatures are not expected
to drop below freezing generally west of US 131 in the Grand
Traverse Bay region. So all rain there. In areas north and east of
there in nrn lower, a period of snow will turn to sleet then
freezing rain. Precipitation will turn to rain south of M-68 in nrn
lower, with eastern upper probably snow for the entire event. The
longest period of time in freezing rain will likely be in the higher
terrain and portions of far NE/nrn lower with ice accumulations
around 0.10" and snow of 1-4 inches, locally higher. Generally less
than 0.10" or less elsewhere in nrn lower with snow less than an
inch. Eastern upper will obviously get the most snow, with 5 to 8
inches. In those areas where snow accumulated initially, the icing
impact may be less. The biggest problem in terms of travel
conditions may turn out to be south of M-72 in the higher terrain,
where the event may be just freezing rain with a tenth of an inch or
less accumulation on roads. Much of nrn lower obviously in a
hazardous situation and advisories have been issued.

Highs Monday ranging from the upper 20s in eastern upper to near 40F
(or more?) in the GTV Bay region and along M-55. Lows tonight
leading into the event, middle 20s north and lower 30s south.

&&

.SHORT TERM...(Monday night through Wednesday)
Issued at 355 PM EST Sun Jan 21 2018

...The Back End of the Storm...

High Impact Weather Potential...Freezing rain/freezing drizzle/snow
mix Monday night turning to all snow by Tuesday

Pattern Synopsis/Forecast...The sfc low and 500 mb low at 00z/Tue
are in the Mid-Mississippi Valley and move into the Upper Great Lakes
by 06z/Tue. This continues to pump warmer air into the forecast
area, and pushes the dry slot in the 700-500 mb layer into the
region. By 12z/Tue, the moisture at all of the levels has filled
back in and any drizzle/freezing Drizzle (mainly from M-32 north to
the bridge) should change back to snow, especially by 15z/Tues. The
low looks to be in southern Quebec by 00z/Wed, and the dry air
begins to clear out the region in the 700-500 mb layer (rh< 20%) and
in the 850 mb level (rh<50%) in C and E Upper and heading into N
lower. 850 mb temperatures by that time are around -10C. Water
temperatures are around +1C to +2c in both Lake Michigan and
Superior. So minor accumulations would be expected by the evening,
tapering to nothing by 06z/Wed. Things cool to -12c/-13c by 12z/Wed,
so something may be possible early, but the wind directions look to
remain NE for most of the day. With water temperatures in Lake Huron
around +2C there could be flurries, but not much more than that with
the dry air over the lake.

Primary Forecast concerns...If the GFS is right with the soundings,
then some of the amount of QPF that the being squeezed out and is
too much, and the amount that is being converted to ice is too much
as well. from the dry air in the upper part of the soundings, We
should be having drizzle/freezing drizzle. I would especially expect
that from about M-32 north, south of there, moisture is in the
sounding and temperatures are above freezing, so rain/drizzle is
possible there. Of course, the other issue is the freezing rain/snow
interface around the Straits. If the moisture and the warm air don`t
get that far north, then all snow could be what happens and the we
could get significantly more snow in E Upper.

&&

.LONG TERM...(Wednesday night through Sunday)
Issued at 355 PM EST Sun Jan 21 2018

Any lingering lake effect snows will diminish by late Thursday and
will be very light as anti-cyclonic flow, light wind flow, shallow
moisture, and marginal 850mb temperatures depart east and high
pressure with much drier air builds over the the forecast area.
Precipitation returns Friday evening/night with return flow ahead of
a developing low pressure system over the northern Great Plains.
This precip appears to be a rain/snow mix Friday night before
turning to all rain late Saturday morning and then turning to all
snow late Saturday night/early Sunday as cold air filters in behind
the departing system. Highs will be in the 20s Thursday and moderate
into the mid 40s by Saturday, temperatures will once again be in the
upper 20s to low 30s Sunday behind the aforementioned departing
system. Lows will be in the single digits Thursday morning, teens
Friday, warming to near 30 by Saturday morning, and then back down
into the 20s Sunday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1200 PM EST Sun Jan 21 2018

Low clouds and fog have stopped advancing northward due to mixing
out, but will likely continue to impact MBL for at least a couple
more hours. All other airports still to see some higher level
cloud passing overhead. Heading through tonight, lowered VSBYS and
CIGS will be the theme with perhaps some drizzle/freezing drizzle
developing late and into Monday. Precipitation turns more rain for
TVC/MBL while more significant snow and freezing rain will impact
PLN/APN. Icing potential through the day of around a tenth of an
inch and snow of 1-3 inches. The light wind regime will turn more
easterly with winds increasing Monday and some gustiness, but the
low levels will be rather stable for any significant gusts. Maybe
some low end LLWS to occur, but confidence is not too high in that
scenario right now.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...WINTER WEATHER ADVISORY from 10 AM Monday to 5 AM EST Tuesday
for MIZ008-015.

WINTER WEATHER ADVISORY from 5 AM Monday to midnight EST Monday
night for MIZ016>019-021-022.

WINTER WEATHER ADVISORY from 5 AM to 6 PM EST Monday for MIZ023-
024.

WINTER WEATHER ADVISORY from 1 AM to noon EST Monday for
MIZ028>030-034-035.

&&

$$

NEAR TERM...SMD
SHORT TERM...JL
LONG TERM...TL
AVIATION...SMD



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