Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 160235

Area Forecast Discussion
National Weather Service Gaylord MI
1035 PM EDT Tue Aug 15 2017

Issued at 1032 PM EDT Tue Aug 15 2017

Not much expected overnight. Plenty of high clouds continue to
spill across the area, and this will remain the case overnight.
These high clouds will do little to quell the nocturnal
temperature response, and given light winds, still expect readings
by morning to drop into the lower and middle 50s across much of
the interior. These cool temperatures may result in some patchy
fog development overnight, especially in those low-lying areas.


.NEAR TERM...(Tonight through Wednesday)
Issued at 252 PM EDT Tue Aug 15 2017

Uneventful wx in the near term. High pressure is skirting by the
north coast of Superior, with ridging extending south toward
eastern Iowa. Plenty of cu in both peninsulas, but as expected,
shortwave ridging and warming temps aloft are keeping a lid on any
potential afternoon convection.

Cu field will diminish this evening, resulting in mostly clear
skies overnight. Surface dew points are still running fairly high
(mid 50s to around 60f), so it will not be difficult to get some
ground fog overnight. After a day of decent mixing and no
significant rainfall, not expected fog to be a major issue.

The high shifts to Georgian Bay on Wednesday, with warm advection
getting underway. Mid clouds will be thickening from sw to ne
during the day, though that will help us from realizing
substantial instability during the day. Any real rain chances
should off after post-sunset.

Min temps tonight mainly in the 50s, though a few upper 40s are
possible in interior cool spots. Max temps Wednesday mainly 70s,
with the TVC area poking up into the lower 80s.


.SHORT TERM...(Wednesday night through Friday)
Issued at 252 PM EDT Tue Aug 15 2017

...Widespread rain possible late Wednesday night-Thursday...

High Impact Weather Potential: Chance of thunderstorms late
Wednesday night through Thursday. Periods of heavy rain also
possible during the same time frame.

Pattern Forecast: Primary features across the midsection of the
country through the forecast period will be a sharpening shortwave
across the Canadian/US border and energy ejecting from the
Intermountain West. Cyclogenesis will be underway across the central
plains tonight before trek northeastward toward the northern Great
Lakes...set to plague the area locally Wednesday night - Thursday.

Primary Forecast Concerns/Challenges: Wednesday night-Thursday`s
heavy rain/thunder potential..

Low pressure across the upper Mississippi Valley Wednesday afternoon
continues to deepen as it slowly progresses northeastward toward the
northern Great Lakes Wednesday evening. Locally, warm air advection
will be underway through most of the day, but really ramps up
Wednesday evening through Wednesday night. As a result, increasing
deep layer moisture and top-down saturation will lead to increasing
shower chances from southwest to northeast after midnight Wednesday
night. At this juncture, the greatest thunder threat arrives during
the day Thursday as northern Michigan lies squarely in the warm
sector. Forecast model soundings suggest a north-south oriented
instability gradient with a couple hundred J/kg of MLCAPE as far
north as ANJ to near 750-1,000 J/kg near the M-72 corridor. Limited
sunshine may hinder instability to some extent, but roughly 30-40
kts of bulk shear progged to be in place Thursday afternoon, prior
to the system`s cold frontal passage Thursday night, lends thought
that a few stronger storms are not out of the question (this thought
supported by SPC`s Day 3 Outlook which extends the MRGL risk as far
north as the M-55 corridor). Locally heavy rain will also be a
concern as PWs are expected to climb to nearly 2.00 inches with a K-
index in the mid-upper 30s by Thursday morning, which is reflected
in WPC`s Day 3 Excessive Rain Outlook encompassing all of northern
Michigan in a MRGL risk.

Expecting a diminish trend in precip coverage/intensity Thursday
afternoon, at least across northern Lower, as the area becomes dry
slotted...evident by forecast soundings suggesting a rather
significant decrease in moisture above 850 mb. The system`s cold
front sweeps across northern Michigan Thursday night; however, wrap
around moisture will warrant keeping low PoPs in the forecast
through Friday as scattered/light showers will remain possible at
times...most numerous across eastern Upper.

Cooler high temps expected Thursday-Friday than seen earlier in the
week ranging from the upper 60s far north to the low-mid 70s

.LONG TERM...(Friday night through Tuesday)
Issued at 252 PM EDT Tue Aug 15 2017

We will see a couple chances for showers over the extended period.
The first could come Saturday, with some isolated afternoon showers
not completely out of the question. High pressure will keep things
dry until the next disturbance rolls through early in the week,
which right now looks to have a better chance of bringing more
widespread showers. Temperatures will run a bit above normal, with a
few days in the 80s possible.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 724 PM EDT Tue Aug 15 2017

Only issue to deal with tonight will be the possible development
of fog/mist as winds remain light and with plenty of lingering
low level moisture. Still think KPLN has the best chance for this
to occur during the early morning hours. More high and mid level
clouds tonight and Wednesday, with more relatively high based
cumulus expected to develop during the late morning and afternoon
hours. Light winds to continue.


Issued at 252 PM EDT Tue Aug 15 2017

High pressure will gradually pass north of Superior. As it does
so, out ongoing northerly winds will veer easterly for Wednesday.
Those winds (east to se) will increase Wed night, and not out of
the question for some advisories to be needed by late Wed night
into Thursday.




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