Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 220250
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
950 PM EST Tue Nov 21 2017

.UPDATE...
Issued at 949 PM EST Tue Nov 21 2017

In eastern upper MI...one dominant band has been slowly pushing
eastward across Luce and western Mackinac Co, and is now edging
into far western Chippewa. Surface winds are already going a bit
more northerly at the twin Saults, implying it will be struggle to
get better lake effect that far east. But that also implies that
convergence to the west could be further enhanced as drainage flow
increases as the pressure gradient relaxes. Will keep potential
snow amounts tonight in western Chip as high as 4 inches. Would
note that the HRRR has very isolated liquid QPF totals up to 0.50
inches from time to time in the Whitefish Bay area. Would also
note that the HRRR has been a little over-exuberant in lake effect
events so far this season.

In northern lower...after the late afternoon and early evening
featured nothing more than flurries, lake effect has intensified
since 8 pm. Dominant band (connecting up to the Superior band
mentioned above) punching into the GLR area presently, though is
still translating eastward. Another stronger band is trying to
organize further west, over northern Gd Trav Bay. Will kick snow
amounts a little higher in nw lower, with some very localized 2-4
inch accums in parts of Charlevoix/Antrim/Kalkaska/Otsego Cos.

None of the above quite rises to the level of an advisory,
especially given the slackening gradient and less blowing/drifting
with time.

&&

.NEAR TERM...(Tonight through Wednesday)
Issued at 309 PM EST Tue Nov 21 2017

High impact weather potential: Minimal.

Pattern synopsis and forecast:

A mid level trough axis was working into the region, with the
associated strong cold front now south and east of nrn Michigan.
Forcing with the trough was a bit better than expected with DPVA
working with RUC analyzed stronger upper divergence. This allowed
for some flurries to develop over nrn lower and some frontally
forced precipitation just scraping Gladwin and Arenac counties.
Otherwise the main show continues to organize itself. Strong cold
advection was allowing for temperatures to fall through this
afternoon, with NW flow lake effect snows already developed and
pushing into eastern upper Michigan. Over the next couple hours,
lake effect will get going over NW lower as the deeper, but not
impressive moisture arrives. High pressure and clear skies were seen
in the middle of the country.

Cold air continues to pour into the region tonight, maxing out
around daybreak Wednesday at -12C to -14C while gusty NW winds taper
down. Moisture is not deep within the convective BL, and inversion
heights vary amongst different data sets. Average inversion heights
are around 5kft or so, with the best of the snows looking to set up
closer to evening. This ought to be the better snow intensities, but
unidirectional flow and a tap from Lake Superior result in hi-res
data suggesting a couple of dominant bands again, while the rest
of the LES likely being quite light as moisture shallows some.
Through Wednesday, the higher pressure will work into the region
with low level winds backing more west then possibly a little
south of west. Continued shallowing moisture will make this more
of just a nuisance snow/flurries type deal with minimal
accumulations. For the remainder of this afternoon through
tonight, 1 to maybe 3 inches in the NW flow snowbelts of nrn
lower, and 1 to 4 inches across eastern upper.

&&

.SHORT TERM...(Wednesday night through Friday)
Issued at 306 PM EST Tue Nov 21 2017

...More Changeable Weather...

A weak short wave moving through the flow will lead to a chance for
a few light snow showers on Thanksgiving Day, otherwise quiet but
chilly holiday weather is expected. Low pressure then approaches
from the west Thursday night into Friday with strong warm air
advection out ahead of it. This will lead to increasing chances for
rain showers (mainly Friday afternoon). Temperatures will be near
normal through Thursday night then rise to a few degrees above on
Friday.

.LONG TERM...(Friday night through Tuesday)
Issued at 306 PM EST Tue Nov 21 2017

...A Continued Roller Coaster Ride...

The up and down weather pattern is expected to continue through at
least the beginning of next week. Colder air moving in behind low
pressure moving by to the north will likely change rain over to a
period of snow early Saturday. This will be followed by a shot of
colder air and lake effect snow showers Saturday into early Sunday.
Model trends are for less available moisture but am still concerned
that we could see icy spots developing early Saturday as
temperatures drop to near freezing followed by accumulating lake
effect snow and blowing snow Saturday into Saturday night as winds
become quite gusty. Lingering lake effect should diminish Sunday due
to increasing ridging aloft. Turning milder once again Monday into
Tuesday with another chance for rain Tuesday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 649 PM EST Tue Nov 21 2017

MVFR tonight at PLN, otherwise mostly VFR with light lake effect
snow.

Cooler air continues to enter the region, behind a cold front
exiting the eastern Great Lakes. Lake effect clouds and snow
showers will be prevalent tonight, but will dwindle on Wednesday.
VFR conditions will be most common, but MVFR conditions may be
seen at times. MVFR conditions will actually be prevalent at PLN
tonight.

Nw winds will remain gusty this evening, then weaken while backing
to the sw thru Wed afternoon.


&&

.MARINE...
Issued at 306 PM EST Tue Nov 21 2017

After a strong cold front crossed the region earlier today, WNW
winds developed and remained quite gusty. For most areas across
Lake Michigan, gales were not being met based on area observations,
so will allow that headline to expire. Gales are likely to continue
through evening in Whitefish Bay and in and around the Presque Isle
Light area. Advisories through tonight all other areas. Higher
pressure and sub advisory winds expected with higher pressure
Wednesday, before winds ramp back up Wednesday night ahead of the
next cold front for potential new advisories.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 6 AM EST Wednesday for LHZ345-346-349.
     GALE WARNING until 11 PM EST this evening for LHZ347-348.
LM...SMALL CRAFT ADVISORY until 6 AM EST Wednesday for LMZ323-341-342-
     344>346.
LS...SMALL CRAFT ADVISORY until 6 AM EST Wednesday for LSZ322.
     GALE WARNING until 11 PM EST this evening for LSZ321.
&&

$$

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



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