Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 160251
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
951 PM EST Thu Feb 15 2018

.UPDATE...
Issued at 951 PM EST Thu Feb 15 2018

The cold front has cleared nrn Michigan, with NW winds in it`s
wake gusting at times while ushering in colder air. The shallow
cooler air is relatively moist, enough to result in advancing
stratus into the region underneath an inversion. Despite to cold
air getting deeper with growing instability coming in off Lakes
Michigan and Superior, doubt there will be much more than
scattered light snow showers and/or flurries, mainly into eastern
upper. Maybe an inch of snow in far western sections of Chip/Mack
counties, with negligible amounts across the GTV Bay region.

A good chunk of NE lower, especially toward Saginaw Bay, may just
see periods of high level clouds which are out ahead of an
advancing weak mid level trough.

Lows in the teens to lower 20s in nrn lower, to possibly as cold
as the upper single digits in eastern upper.

&&

.NEAR TERM...(Tonight through Friday)
Issued at 307 PM EST Thu Feb 15 2018

...Turning cold again tonight with some light lake effect snow
showers...

High Impact Weather Potential...None.

Pattern Synopsis/Forecast...Complex area of low pressure continues
to develop to the lee of the Central Rockies...while another more
established area of low pressure is centered just north of Michigan
this afternoon. Warm front associated with the Central Plains low
continues to produce a large area of mainly light rain showers
impacting areas north of the Ohio Valley into the Southern Great
Lakes. Northern edge of this rain shield is just skimming the
southern border of our CWA this afternoon...with a few locations
periodically reporting some light rain reaching the surface. This
precip will come to an end during late afternoon as the dry slot
over most of our area sags further south.

Attention then turns to the upstream cold front currently extending
from the low centered to our north westward thru Western Upper
Michigan...NW Wisconsin into Southern Minnesota. This cold front
will swing thru our CWA early this evening...ushering much colder
air back into our region. Low level flow will shift to the N/NW as
colder air activates the lakes. Moisture will be limited and
shallow...which will limit the potential accumulation. Most of our
areas impacted by N/NW flow will receive less than an inch of new
snow tonight. With CAA underway...overnight lows will drop into the
single digits above zero across Eastern Upper Michigan and into the
teens across Northern Lower Michigan.

Strong surface ridge axis moves overhead on Friday...bringing a
close to residual lake effect snow shower activity by afternoon.
Additional snow amounts will be well under an inch during the
morning. We should see some sunshine by afternoon as well...but
temps will be relative cold (at least in comparison to the past
couple of days). Afternoon highs will generally be in the low to mid
20s.

&&

.SHORT TERM...(Friday night through Sunday)
Issued at 307 PM EST Thu Feb 15 2018

...A couple rounds of light snow over the weekend...

High Impact Weather Potential...Minimal, with only light snow
accumulations expected.

Pattern Synopsis/Forecast...Surface high pressure will drift across
the Ohio Valley Friday night, with ridging and dry low level air in
place across northern Michigan. Return flow on the backside of this
high will lead to increasing moisture and breezy conditions across
the region on Saturday as the system departs. A shortwave will cross
the region beginning midday, with a surface low over Hudson Bay
dragging a trailing cold front through northern Michigan Saturday
evening-night. Surface ridging returns Sunday morning followed by a
warm front and strong warm air advection lifting through during the
afternoon.

Primary Forecast Concerns...Snow chances through the weekend.

Dry low level air and increasing subsidence will keep things dry
Friday night into Saturday morning. Increasing return flow will
bring a plume of higher moisture into the area by Saturday
afternoon, with PWATs climbing above 0.25 inches. The approaching
cold front and shortwave will interact with this moisture to produce
light snow across the area. One concern will be whether there could
be some possible lake enhancement in the generally southwest flow
off Lake Michigan. Current lake temperatures range from 2 to 4C mid-
lake, while forecast 850mb temperatures look to be around -9 to
-10C. So, delta Ts would at best be marginal for some lake
enhancement, but it`s at least a small possibility for western
Mackinac County and near Lake Michigan across northwest Lower. Snow
to liquid ratios look to be below 20:1, but given the breezy SW
winds, there could be some blowing snow in spots...especially across
the frozen northern tip of Lake Michigan which could result in low
visibilities across portions of US-2. Something to monitor. Still
looking like around an inch or two west of I-75 and across eastern
Upper, with those 2 inch amounts in the possible lake enhancement
areas.

The next disturbance rolls through mainly the northern half of the
forecast area Sunday afternoon into Sunday night. Mostly snow with
this system, but there could be a bit of rain that mixes in near the
Grand Traverse Bay region where temperatures rise into the mid 30s.
The bulk of snow accumulation will be north of the Straits.

.LONG TERM...(Sunday night through Thursday)
Issued at 307 PM EST Thu Feb 15 2018

High impact weather potential: Minimal; with a warm first half
trending colder during the second half of the forecast period.

At upper levels, broad 500mb troughing will be in place over the
eastern two thirds of the country to begin the work week, before a
500mb trough drops into the northern Plains and over the Great Lakes
by the end of the work week. This upper level pattern will generate
above normal temps across northern Michigan through Tuesday, as
850mb temps warm to +8c. However, temperatures fall back to more
seasonal readings around 30 degrees after Tuesday, as the upper
level trough pushes into the Great Lakes.

At the surface, a storm system over the central Plains during the
weekend, will lift north into the nrn Great Lakes by Tuesday, before
slipping east of the region Wednesday. This pattern will transit any
snow Sunday night to rain Monday and Tuesday, before colder air and
snow return to the forecast area Wednesday and Thursday on the
backside of the exiting storm system.

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 616 PM EST Thu Feb 15 2018

The cold front has crossed all airports early this evening, with a
tighter pressure gradient and cold advection bringing some gusty
conditions that will last through the night and into Friday. In
the shallower cool air, it`s moist enough for prevailing MVFR for
much of the night, with a shorter period at PLN. A disturbance
aloft and marginally sufficient overlake instability develop late
tonight into daybreak Friday, for a brief period where light snow
shower or flurries are possible around TVC/MBL. Much drier air
then filters in and skies clear out into Friday night. Maybe a
small chance for low end LLWS Friday night as well.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
&&

$$

UPDATE...SMD
NEAR TERM...MR
SHORT TERM...MK
LONG TERM...SR
AVIATION...SMD



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