Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 130651

Area Forecast Discussion
National Weather Service Gaylord MI
251 AM EDT Tue Mar 13 2018

.NEAR TERM...(Today through Tonight)
Issued at 243 AM EDT Tue Mar 13 2018

High impact weather potential: Continued snow shower activity,
particularly in NNW flow regimes. Snow showers likely modified by
diurnal processes, as well as periods of enhancement from sfc and
mid level trough passages. Bursts of snow expected resulting in
relatively brief periods of heavier snows and poor visibility at

Pattern synopsis and forecast:

The general synoptic pattern features deep upper troughing over the
Great Lakes/eastern conus, with ridging over the western part of the
country. One vigorous shortwave was closing off over the Atlantic
and resulting in deep low pressure working up the Atlantic coast.
This system was ingesting shortwave energy from a wave in PA, which
is part of a larger scale upper low over the nrn Great Lakes, which
contained other sfc and mid level troughs. One of these troughs was
working through Lake Superior. A tighter thermal gradient in CAA
under steeper low to mid level lapse rates has resulted in more
vigorous lake enhanced snow shower convection pressing through upper
Michigan. The deeper instability was overtaking low level shear,
resulting in a continued more cellular nature of the showers, and
more "bursts" of rather intense snows. Some of this energy was
currently working down into NW lower Michigan, and latest radar
has shown signs of increasing/strengthening snowfall aimed
primarily across the GTV Bay region in NNW flow. Less fetch and
not as cold low level temperatures in eastern upper and NE lower
has kept the activity weaker. Additional shortwave energy was
noted in Ontario, wrapping around the nrn/western periphery of the
broader upper circulation.

Am expecting the snowfall to continue to increase in intensity and
coverage in the NNW flow regimes, while remaining cellular in nature
due to deepening instability. The stronger snow showers, even those
last evening, were resulting in relatively brief but nearly blinding
visibilities and quick light accumulations of snow. Some of these
snow showers will also train over the same areas a few times with
localized areas getting up to a couple inches of snow, likely more
of an exception than the rule. A downtick in activity is expected
behind the wave, but the aforementioned additional energy arrives
by late morning to re-energize things once more. This activity is
likely to trend more enhanced over land due to diurnal heating.
After more energy drops in from the north in the afternoon and
evening, the larger scale upper low circulation starts to depart
south and east. This complicated synoptic pattern and evolution
will result in periods of snow showers across the region,
remaining more intense and frequent in the NNW flow regimes in and
around the GTV Bay region. Many locations could see 2-4 inches of
snow by tonights end. The impacts however, will revolve around the
bursts of snow and poor visibility/hazardous driving conditions
that result, including this morning`s commute. Will not issue any
advisories, but special weather statements are likely to be

Highs today will be a touch colder due to CAA, in the upper 20s to
lower 30s most areas. Lows tonight in gradual expanding areas of
thinning clouds, in the teens most areas. Protected low lying areas
that clear can easily see single digit readings.


.SHORT TERM...(Wednesday through Thursday)
Issued at 243 AM EDT Tue Mar 13 2018

...Light lake effect potential returns Wednesday night-Thursday...

High Impact Weather Potential: Minimal, although some light lake
effect is possible late Wednesday night-Thursday.

Pattern Forecast: Brief upper level ridging and associated low level
warm air advection will become centered across northern Michigan
during the day Wednesday. However, another piece of arctic energy is
expected to drop down across the the upper Great Lakes Wednesday
night into Thursday, perhaps providing enough cold air and synoptic
moisture/support to kick off another round of scattered/light lake
effect snow showers.

Primary Forecast Concerns/Challenges: Light lake effect snow
chances late Wednesday night into Thursday across portions of
northwest lower and eastern upper Michigan.

Little in the way of sensible weather is anticipated Wednesday as
the onset of warm air advection is expected to bring any lingering
light lake effect to an end early in the day. Partly sunny skies and
temperatures near normal (ranging through the 30s area-wide) will be
the rule.

Another piece of arctic energy is expected to dive southward into
the northern Great Lakes as early as Wednesday evening. As a result,
cold air advection is expected to take over throughout Wednesday
night with H8 temps falling to roughly -11 C by early Thursday
morning. Despite marginal over-lake instability and a rather dry
atmosphere, wouldn`t be shocked with help from a bit of synoptic
forcing for scattered lake effect snow showers/flurries to develop
in primarily northwest flow across the typical areas of northwest
lower and eastern upper. Any snow showers are expected to be rather
short lived with limited accumulation, especially during the
daylight hours Thursday. Thursday`s high temps several degrees
cooler than Wednesday...ranging from the upper 20s north the mid-30s
near Saginaw Bay.


.LONG TERM...(Thursday night through Monday)
Issued at 243 AM EDT Tue Mar 13 2018

High Impact Weather Potential: Minimal.

A rather quiet extended period is anticipated across the bulk of
northern Michigan as guidance has come into better agreement within
the past 24 hours regarding high pressure gradually sagging into the
region this weekend and a developing area of low pressure passing by
to our south early next week. High temperatures both days this
weekend expected to climb slightly above normal...varying from the
upper 30s across eastern upper to the low-mid 40s near Saginaw Bay.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1139 PM EDT Mon Mar 12 2018

Challenging forecast with regards to snow shower intensity and
coverage continues. Trends still support heaviest and steadiest
snows targeting areas closer to Lake Michigan and Lake Huron
through through this morning. Still not completely sold on this
idea as low level flow veers a bit northeast before coldest air
arrives (especially off Lake Michigan). Will tentatively use tempo
wording as a means to express uncertainty with regards to vis
restrictions and lower cloud bases. Otherwise, expecting just
some passing light snow showers and mostly VFR/MVFR cigs. Gusty
northwest to north winds will develop through today. Snow to
liquid ratios will remain elevated, averaging around 18/20-1. Any
blowing snow concerns should remain minimal.




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