Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 230402

Area Forecast Discussion
National Weather Service Gaylord MI
1102 PM EST Thu Feb 22 2018

Issued at 947 PM EST Thu Feb 22 2018

Not really a whole lot of change to the ongoing forecast, based on
latest rapid update data. The main precipitation may hold off 2-3
more hours than originally thought, but sfc temperatures still
look to remain at or below freezing at onset, aided by a period of
evaporative cooling due to the dry low level atmosphere. The warm
nose aloft still expected to be in place at onset as well for nrn
lower (or right when main precipitation occurs). This will still
set the stage for light freezing rain to develop late tonight into
Friday morning, spreading from SW to NE. In addition, could be
some freezing drizzle ahead of the main batch of precipitation
(this is occurring now in parts of srn Wisconsin and Iowa). All
in all, still a good threat for slippery roads to develop. Current
headlines will hold. Did add fog to the forecast as T/Td spreads
look to be quite small, with Td`s in the lower half of the 30s
over snow/cold ground. Not expecting anything dense however.


.NEAR TERM...(Tonight through Friday)
Issued at 315 PM EST Thu Feb 22 2018

...Another round of a wintry mix of precipitation later tonight
into Friday...

High impact weather potential: Mixture of snow, sleet, and freezing
rain expected to bring some difficult driving conditions later
tonight into Friday.

Pattern synopsis/forecast: Active pattern remains as deep southwest
flow continues between anomalously strong west Atlantic ridging and
nearly as impressive western trough axis. Elevated warm air
advection and overhead upper jet core bring plenty of mid and upper
level clouds to northern Michigan, although maintenance of
impressive low level dry wedge is keeping conditions dry. That is
about to change as wave at base of western trough follows a similar
path to its predecessors, cutting across the northern Lakes later
tonight and Friday. Attendant northward surging warm nose aloft and
stubborn to yield low level cold dome once again sets the stage for
a wintry mix of precipitation to overspread the region.

Primary forecast concerns/challenges: Addressing timing and amounts
of that wintry mix of precipitation, as well as attendant headline

Details: Dry evening gives way to more active weather later tonight
into Friday as strong waa and deeper moisture surge north along with
that ejecting wave. Greatest mid level support passing to our
northwest, and convection well to our south partially impacting
northward moisture transport, does argue for an overall light precip
event (largely under a quarter of an inch) for northern lower, with
slightly heavier amounts north of the big bridge. What type that
precip takes remains a much more formidable forecast challenge. Warm
nose aloft surges north nearly in lock-step with precipitation later
tonight, with above freezing elevated warm layer reaching up near
the Straits by morning. Initial dry lower levels does allow some
evap cooling potential, perhaps delaying this northward warm surge
just a bit, allowing a period of snow/sleet mixture (especially
further north). Still think much of northern lower experiences at
least a period of freezing rain/drizzle as overnight surface
temperatures dip below freezing, with the greatest impacts centered
on the interior highlands where surface cold air will be a bit more
stubborn to yield. Not expecting any significant ice accumulations,
likely at or under a tenth of an inch. Warmer surface air and loss
of better dynamics does change precip over to just plain light
rain/drizzle from southwest to northeast during the morning. Still,
given expected impacts during the morning commute from that light
icing, with go ahead and issue a winter weather advisory for much of
northern lower Michigan later tonight through Friday morning. As for
eastern upper...they definitely look to stay in the cold air much
longer, supporting mainly snow before transitioning over to a light
mixture just as precip ends early Friday afternoon. While expected
QPF amounts alone does support advisory level snow amounts, perusal
of guidance derived soundings show a very elevated dendritic growth
layer and an extended in-cloud layer warmer than -10c...both
supporting much lower than climo snow-to-liquid ratios. While
expected snow amounts of 2 to 3 inches is below advisory level
criteria, very wet nature of the snow and brief periods of very
restricted visibility will no doubt result in some significant
travel impacts. After coordination with MQT, will go ahead and
introduce winter weather advisories for our eastern upper counties


.SHORT TERM...(Friday night through Sunday)
Issued at 315 PM EST Thu Feb 22 2018

..More freezing rain likely Sat night; very windy Sunday...

Primary Forecast Concern...Freezing rain potential Sat night/early

The mild but active weather pattern will continue through this
weekend. As far as the weather goes, high pressure will lead to
quiet conditions Friday night into Saturday. A potent but fast
moving area of low pressure tracking by to our west will then likely
bring another period of freezing rain (possibly starting as a
little snow or sleet) overnight Saturday into early Sunday across
northern lower with snow and freezing rain expected across
eastern upper. This could lead to slick roadways and difficult
travel conditions once again. Very windy conditions expected
Sunday with wind gusts possibly reaching between 40 and 50 mph.
High temperatures Saturday and Sunday in the middle 30s to the
middle 40s. Lows Friday night in the upper teens and 20s followed
by lows in the middle 20s to lower 30s Saturday night.

.LONG TERM...(Sunday night through Thursday)
Issued at 315 PM EST Thu Feb 22 2018

A deepening low pressure system over the Upper Mississippi River
Valley will make it`s way into the northern Great Lakes region
Saturday night...producing precipitation throughout the entire
forecast area. The exact track of said storm system and
precipitation type remains a bit uncertain as long range models seem
to be in disagreement. As this system departs it is safe to say that
there will be a bit of light lake effect snow/clouds as colder air
filter in on westerly winds by Sunday afternoon. This lake effect
will be light as delta ts are very marginal, drier air moving in,
and flow is anti-cyclonic with a strong high pressure system
building into the great lakes from the south. These westerly winds
will be gusty, with winds of 25-30mph possible. A clipper system
then skirts the northern Great Lakes producing more chances of light
snows through Wednesday. High temperatures will generally be in the
low 30s to near 40, while lows will be in the 20s.


.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1102 PM EST Thu Feb 22 2018

VFR conditions will give way to MVFR/IFR conditions very late
tonight into Friday morning as low clouds and a light mixture of
freezing rain, sleet, and snow spread north across the airports.
Not expecting too much precipitation, but light snow and freezing
rain will definitely have some impacts. Precipitation and areas of
fog ending late morning into early afternoon, but MVFR CIGS
expected to hold into the evening, scattering out late Friday
night. Current low level wind shear will slowly end Friday

Around an inch expected at PLN with primarily just light freezing
rain changing over to rain/drizzle. Ice accumulations around 0.05"
or less.


MI...WINTER WEATHER ADVISORY until 11 AM EST Friday for MIZ016>036.

WINTER WEATHER ADVISORY until 1 PM EST Friday for MIZ008-015.



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