Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 220307

Area Forecast Discussion
National Weather Service Gaylord MI
1007 PM EST Wed Feb 21 2018

Issued at 1006 PM EST Wed Feb 21 2018

The storm system which generated widespread rains and ultimately
some flooding over the Great Lakes earlier, has now exited east
of the region. A large area of high pressure from the Plains, has
pushed west and will become centered over the Great Lakes through
Thursday night. Model soudnings and moisture progs showing an
extremely dry airmass over most of northern Michigan this evening,
which is forecast to continue through Thursday afternoon. Mid and
upper lvl moisture does eventually increase over northern
Michigan Thursday night and Friday, as yet another storm system
lifts up into the northern Great Lakes.

Temperatures are currently in line with the latest hourly temp and
dew pt trends. Dew pts falling into the mid teens should continue
into the single digits, with overnight temperature trends falling
to between 10 and 13 degrees away from the Great Lakes.


.NEAR TERM...(Tonight through Thursday)
Issued at 309 PM EST Wed Feb 21 2018

...A bit chilly tonight...

High impact weather potential: Lingering high river levels,
especially on the Rifle River near Sterling.

Pattern synopsis/forecast: The soaking rain and record warmth of
yesterday is now well to our southeast as seasonably chilly high
pressure builds into the region. Shallow lake processes in post-
frontal caa environment continues to slowly fade, leaving behind
some passing high clouds within upper level southwest flow regime.

High pressure will continue to slide east, centering itself nearly
overhead by later tonight. Next southwest system begins to approach
the area Thursday, bringing our next threat for a wintry mix of
precipitation to end the week.

Primary forecast concerns/challenges: Temperature and cloud trends.

Details: First order of business remains ongoing high water and
flooding down near Saginaw Bay. Rivers remain elevated in that area,
with reports of flooding along the Rifle and Tobacco Rivers. Other
reports of high water and nuisance type flooding elsewhere. Most
runoff has stopped, but still expect water levels to remain elevated
into Thursday. Have gone ahead and extended river and areal flood
warnings through the near term.

Otherwise, as mentioned, high pressure will build overhead tonight,
bringing dry weather along with it. Lingering lake clouds expected
to scour out quickly, leaving behind just some thin cirrus. Combine
that with light winds, and would expect a rather sharp nocturnal
temperature response this evening. Lack of fresh snow cover will
keep temps from really tanking, but did side with the colder end of
the statistical guidance spectrum, with interior colder locations
dropping into the single digits by morning.

Conditions expected to remain dry Thursday, although with increasing
high and mid level overcast as slow top-down saturation begins ahead
of next approaching wave. Did the opposite with regards to
temperatures, taking the warmer end of guidance as filtered sunshine
and plenty of bare ground should allow for some decent warming.
Expect afternoon temperatures to run a bit above normal, with
readings ranging from the upper 20s to middle 30s.


.SHORT TERM...(Thursday night through Saturday)
Issued at 309 PM EST Wed Feb 21 2018

...Another wintry mix...

High Impact Weather Potential...Increasing confidence in potential
for another wintry mix Friday morning, including some light icing.

Pattern Synopsis/Forecast...Surface high pressure will be retreating
off to the east through the first half of Thursday night. As it
does, an upstream shortwave will cross into the Upper Great Lakes
late Thursday night into Friday morning. A surface low developing in
response over the region will interact with a tight thermal gradient
across the Ohio Valley and Lower Great Lakes, drawing some of the
warmer air northward. This will set the stage for another round of
mixed precipitation through Friday morning across northern Michigan.
High pressure accompanied by a drier airmass will build in from the
west Friday evening, drifting across northern Michigan early
Saturday. Another developing system will lift into the region as
early as late Saturday afternoon.

Primary Forecast Concerns...Precipitation types and possible light
icing with Friday`s system.

Confidence continues to increase in the potential for another round
of mixed precipitation across the area in the late Thursday night
through Friday morning timeframe. However, moisture with this system
is looking much less impressive than with the system earlier this
week, and it looks like the heaviest precip across the region will
occur along the frontal boundary over the Ohio Valley. More locally,
the "heavier" (used in a relative sense) precip across northern
Michigan looks to set up near and north of the Straits. That`s good
news for areas south of M-55 that have been dealing with residual
flooding from earlier heavy rainfall and snowmelt.

Precip should start out as light snow early Friday morning until the
warm nose begins to creep in from the south before daybreak. The
warm nose isn`t looking quite as warm as it did for yesterday`s
forecast but still looks to max out somewhere around +3 to +5C near
850mb. So, expect the initial snow to give way to freezing rain from
south to north Friday morning, perhaps with some sleet mixed in at
times. As surface temps eventually begin climbing mid-late morning,
we should see a gradual south-to-north transition to just rain. Then
by midday, forecast soundings show moisture stripping out pretty
rapidly aloft, leaving just a shallow saturated layer near the
surface. This would lend itself to perhaps some drizzle and freezing
drizzle Friday afternoon. Potential ice amounts (generally less than
a tenth of an inch across most of the forecast area) not looking as
serious as the last system, but they still could certainly have an
impact on travel by making untreated roads slick. Additionally, up
to an inch of snow (perhaps 2" across eastern Upper) will be
possible for much of the forecast area.

.LONG TERM...(Saturday night through Wednesday)
Issued at 309 PM EST Wed Feb 21 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 00Z TAFS through 00Z Thursday evening)
Issued at 643 PM EST Wed Feb 21 2018

A large area of high pressure over the Upper Plains, will continue
to push into the Great Lakes, becoming the main influence over
northern Michigan through Thursday night. CIGS and VSBY will largely
remain VFR through the period as high pressure and dry air influence
the region. However some lower MVFR cloud is expected along portions
of the Lake Michigan shoreline tonight, the result of lingering low
lvl moisture and marginal over lake instabilty.




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