Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 150321
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1021 PM EST Wed Feb 14 2018

.UPDATE...
Issued at 1021 PM EST Wed Feb 14 2018

Pretty tight WSW flow aloft this evening with a couple of minor
shortwaves working across the area, resulting in nothing more than
some higher cloud. Low level winds have increased out of the S/SW,
and continued to feed increasing BL moisture northward, having
reached MBL/CAD/Gladwin county now with low level stratus and
light fog in the observations. There has been somewhat of
increased confidence in this stratus and light fog spreading
north across most all of nrn Michigan through the remainder of the
night, as temperatures slowly fall and sfc dewpoints rise some.
Based on satellite, the moisture does look pretty shallow, and
just not sure of the whether or not it locks in solid into a good
chunk of tomorrow morning. The shallow moisture really leads me to
think that chances for drizzle/freezing are quite minimal. Maybe
into the higher terrain due to upslope.

&&

.NEAR TERM...(Tonight through Thursday)
Issued at 246 PM EST Wed Feb 14 2018

...Just a bit cooler Thursday...

High impact weather potential: Some concern for a bit of freezing
drizzle later tonight, especially for eastern upper Michigan.

Pattern synopsis/forecast: Much advertised warm-up has come to
fruition as deep southwest flow has overspread the northern Lakes.
H8 temperatures spiking well up into the single digits, with good
mechanical mixing and abundant sunshine helping tap just a bit of
this warming aloft. The result, current readings punching up into
the 40s across most of northern lower Michigan...a good 10 or more
degrees above normal for this time of year. All this warmth made so
be strong pressure gradient between departing west Atlantic high
pressure and weak low pressure racing along the Minnesota/Canada
border. This low will continue to race east, pushing across Lake
Superior tonight, reaching Quebec as quickly as early Thursday
afternoon. Strong warm air advection continues into Thursday, with
passing of a weak cold front tied to that passing low cooling things
through the end of the week.

Primary forecast concerns/challenges: Temperature/cloud trends and
addressing the potential for some freezing drizzle tonight and early
Thursday.

Details: Really challenging (and low confidence) forecast tonight
with regards to low cloud and drizzle development. No low clouds
remotely close to us now, with the nearest stratus well to our south
across the Ohio Valley. Backward run trajectory analysis does show
our low level source region from this area tonight, and when
combined with boundary layer cooling and moisture flux via afternoon
snow melt definitely does support stratus/mist/fog development
overnight. However, as experienced many times, guidance is often way
too aggressive with low level moisture advection in such a dry
environment. Gonna play it conservatively for now, delaying low
cloud development by several hours and forgoing any fog mention.
Moisture does remain very thin, also throwing a wrench into guidance
progs showing rapid drizzle development. Will not go nearly as
widespread, but feel at least some patchy drizzle wording is
warranted. Nocturnal temperature response will be a slow one given
maintenance of southwest winds. Temperatures will flirt with the
freezing mark, especially across eastern upper Michigan, resulting
in some freezing drizzle concerns. Not headline worthy, so will
continue to use the hazardous weather outlook as an avenue to
express this potential.

Area gets largely split from better forcing Thursday, with waves
riding to our north and south. Late day cold front does bring some
deeper moisture along with it, supporting more drizzle/light snow
showers, especially further north. Given less than originally
expected precip and a somewhat delayed frontal passage, have sided
toward the warmer end of the statistical guidance spectrum,
featuring highs in northern lower Michigan once again topping 40
degrees.

&&

.SHORT TERM...(Thursday night through Saturday)
Issued at 246 PM EST Wed Feb 14 2018

...Light lake effect chances Thursday night-Friday...

High Impact Weather Potential: Minimal.

Pattern Forecast: Weak troughing will gradually become renewed
across the Great Lakes on Thursday night behind a cold front that
progresses across the area earlier in the day. Cold air advection
will be the rule through Friday all while surface high pressure
spills into the region from the west. Aside from perhaps a bit of
light lake effect snow Thursday night into Friday, the threat for
additional wintry precip is not expected until late Saturday as snow
showers develop ahead of a well-defined mid-level perturbation.

Primary Forecast Concerns/Challenges: PoPs thursday night and Friday.

Cold air advection firmly underway across the area Thursday night
aids in dropping H8 temps from roughly -6 C at 00z Fri to -16 C by
12z Friday. Despite sufficient over-lake instability, any lake
effect activity is expected to remain rather light/scattered as
moisture fields remain anemic with very little synoptic support.
Greatest threat for snow showers will fall across the typical NNW
flow lake belts of NW lower/eastern upper with an inch or less of
accumulation expected where snow falls steadiest.

High pressure gradually presses east across the area...becoming
centered over NE IL by Friday evening. As a result, any lingering
scattered snow showers taper throughout the day with increasing
afternoon sunshine. Chilly temperatures will be the rule Friday
through Friday night with high temps back down into the mid teens to
low 20s area-wide and overnight lows in the single digits.

Quiet weather is expected to prevail for much of Saturday, although
a well-defined mid-level wave approaches the western Great Lakes
during the afternoon, perhaps sparking off scattered snow showers
across parts of northern Michigan. At this point, any snow
accumulation looks to be minor. Saturday`s high temps boost into the
mid-upper 20s across all of northern Michigan.

.LONG TERM...(Saturday night through Wednesday)
Issued at 246 PM EST Wed Feb 14 2018

The forecast period begins with a weak cold front extending from a
low pressure system over Hudson Bay...producing only light snow
showers. By Sunday afternoon a very short break of precip free
weather associated with a ridge of high pressure from the Ohio River
Valley will occur through the evening hours. By late Sunday night
long range models have a developing low pressure system over the
central Great Plains with WAA precip ahead of it beginning to effect
northern Michigan. This precipitation has a good chance to be mixed
precip, with even some freezing rain/drizzle at times Monday
afternoon and again Tuesday. Wednesday the models differ greatly
with another chance of mixed precip or possibly some snow
accumulations.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 640 PM EST Wed Feb 14 2018

...Somewhat higher confidence with regards to cig heights and
vsbys due to fog/mist development tonight and Thursday...

Still a tough forecast heading through tonight as low level
moisture increases below strong near-surface inversion, via
strengthening SW low level winds, which will bring LLWS to all
airports tonight. IFR/MVFR CIGS are already seen pressing
northward through srn WI/MI, which will arrive/expand into nrn
Michigan mainly after midnight. There can easily be some reduced
VSBYS due to fog and possible drizzle, as higher dew point air
advects in over cold Lake Michigan and snowpack. Not sure if low
clouds mix out Thursday, but VSBYS expected to improve through the
day. A cold front arrives Thursday afternoon into Thursday
evening, turning winds more west, then NW.

Wind shear across all locations tonight.


&&

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

$$

UPDATE...SMD
NEAR TERM...MB
SHORT TERM...MG
LONG TERM...TL
AVIATION...SMD



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