Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 240400
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1200 AM EDT Thu May 24 2018

.UPDATE...
Issued at 1155 PM EDT Wed May 23 2018

With the fog/stratus starting to pile up into the Mack Co
shoreline, and the s-to-n thinning trend over northern Lake MI
slowing down, went ahead and posted a dense fog advis for Mack Co
into Thu morning. Much of the high-traffic US-2 corridor is
potentially impacted by this marine fog.

UPDATE Issued at 1035 PM EDT Wed May 23 2018

Marine fog/stratus over Lake MI has been gradually migrating
northward, as a bit of return flow develops behind high pressure
still centered downstate. Per satellite and obs, most of the
fog/stratus is now near/north of Leland (including spilling into
the Straits). Interior sections still have very healthy temp/dew
point spreads (Kinross 68/44f), which will severely limit inland
penetration, as least until those spreads narrow. It is not clear,
give thinning occurring from south to north, how much marine
fog/stratus will actually be left by the time this happens.

Am fine-tuning cloud cover and fog trends, but in general will
continue to limit inland penetration of the above tonight.

Otherwise, the night is quiet, with only minor tweaks to temps.

&&

.NEAR TERM...(Through Tonight)
Issued at 320 PM EDT Wed May 23 2018

...Quiet weather continues...

High Impact Weather Potential: None.

Pattern Synopsis/Forecast...Afternoon composite analysis reveals
sharp ridging from the Midwest up through central Canada. Expanse of
high pressure stretches from the Hudson Bay and Great Lakes regions
south to the Gulf Coast, along with a nice pocket of dry air across
the Great Lakes and Ohio Valley. Another nice day out there overall.
But, Lake Michigan marine stratus/fog has been skirting parts of the
lakeshore all day, particularly around Frankfort and into Leelanau
county where coastal fog has been a let down today. Also, pocket of
higher dewpoint air noted over the SW counties (TVC/CAD have
dewpoints in the mid to upper 50s) actually generating some SBCAPE
and modestly agitated CU field across that area.

Upper ridge axis will slowly build into the Great Lakes over the
next one to two days, maintaining this run of quiet weather, along
with warming temps/increasing humidity as we get on the backside of
the surface high.

Primary Forecast Concerns: Stratus/fog trends. As mentioned above,
stratus/fog has plagued Lake Michigan and parts of the shoreline
through the day. Always a tough call figuring out what it`s going to
do. But with the low level flow increasing from the SW, marine
stratus/fog will probably creep up the shoreline and through the
Straits as we go through tonight. Even more unclear whether or not
we get some stratus/fog to penetrate inland into parts of the NW
lower Michigan and the eastern U.P. I don`t have that currently in
the forecast, but evening/midnight shifts will want to monitor
stratus trends.

&&

.SHORT TERM...(Thursday through Saturday)
Issued at 320 PM EDT Wed May 23 2018

...High pressure exiting stage right...

High Impact Weather Potential: Scattered thunderstorms, especially
Friday and Saturday

Pattern Synopsis/Forecast: The broad area of high pressure that has
been over the region for the past few days will begin to move out of
the area Thursday. An upper level low currently sitting over the
Desert Southwest move along the western periphery of a broad area of
ridging spanning the eastern 2/3rds of the CONUS. This shortwave is
set to affect us as early as Thursday night and lasting through
Saturday.

Primary Forecast Concerns: There are a couple of things to keep an
eye on in the short term. As high pressure continues to remain
overhead, temperatures will continue to warm. As the high pressure
center gets to our east, flow will turn southwesterly increasing
both moisture and warm air advection. Flow ahead of the approaching
shortwave will only serve to enhance this. Friday high temperatures
in the blend are in the mid to upper 80s, but I wonder if they may
get even warmer. A lot of times when the ridging gets folded into
the region, and ahead of an approaching system, temperatures really
climb.

The second area of concern will be with the rain/thunder potential
over the weekend, especially being a holiday weekend. While the Gulf
will be closed, there are PWATS in the 1.5" neighborhood stretching
through the Plains that the approaching shortwave will advect with
it. This will not only add to the humidity, but will help to
increase instability, especially Friday and Saturday. Wind shear
looks rather anemic for supporting severe development at this time,
but there is enough instability that some scattered thunderstorms
could develop. Rain chances will start across the U.P. Thursday
night, spreading across northern lower Friday and Saturday.

.LONG TERM...(Saturday night through Wednesday)
Issued at 320 PM EDT Wed May 23 2018

...It`s deja vu all over again...

While there may be some energy slower to clear out Sunday, the first
half of next week looks to be very similar to the past few days.
High pressure setup over the region will bring warm and dry
conditions, with temperatures continuing to run well above normal.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1159 PM EDT Wed May 23 2018

Mostly VFR, but PLN will likely see some early morning fog.

High pressure is centered over southern lower MI, with generally
dry air in place. However, some fog/stratus continues over the
chilly waters of Lake MI. This will gradually get pushed ne-ward
into parts of upper MI, but could potentially bring some
fog/stratus to MBL and especially PLN overnight into Thursday
morning. Otherwise, continued VFR.

As the high moves slowly east, a bit of a sw breeze will develop
on Thursday, though onshore lake breezes return in the afternoon.
LLWS develops Thu evening PLN/TVC.

&&

.MARINE...
Issued at 320 PM EDT Wed May 23 2018

Dense fog will linger over Lake Michigan through Thursday afternoon,
with dense fog advisories from Manistee to the Straits. Winds will
begin to pick up Thursday afternoon ahead of an approaching low
pressure system. Expect winds to stay in the 15 to 20 knot range
through Friday, with thunderstorm development possible Friday
evening.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...DENSE FOG ADVISORY until 11 AM EDT Thursday for MIZ015.
LH...DENSE FOG ADVISORY until 11 AM EDT Thursday for LHZ345.
LM...DENSE FOG ADVISORY until 11 AM EDT Thursday for LMZ341-342-
     344>346.
LS...NONE.
&&

$$

UPDATE...JZ
NEAR TERM...ADAM
SHORT TERM...AM
LONG TERM...AM
AVIATION...JZ
MARINE...AM



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