Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 252009

Area Forecast Discussion
National Weather Service Marquette MI
409 PM EDT Tue Jul 25 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 409 PM EDT TUE JUL 25 2017

A low pressure system currently over central Manitoba will shift E
across far northern Ontario tonight and Wed. A SFC trough and cold
front extending from the low will trek across the area tonight and
Wed, with a shortwave running just ahead of the front. The most
attention is on early tonight when elevated instability should
increase from the SW. Models suggest MUCAPE increase somewhere in
the 1,500-2,500 J/kg range over the central and W, and 800-1,500
J/kg over the E, with 20-30kts of shear. Elevated hail storms are
certainly a possibility, mainly over the central and W but can`t
rule out some strong to sever hailers over the E. Still a lot of
uncertainty as it is unknown exactly how much instability will
develop and where storms will develop and track. Best estimate for
timing based on hi-res models is that storms will move in from the W
around or after midnight tonight.

The cold front slows across the area and moves through the S-central
and E tomorrow. The front will bring precip chances that will sag SE
with time late tonight into Wed, possibly reinvigorating some
convection over the S-central and E tomorrow afternoon. Not
completely out of the question for some of that convection to be
strong, but not expected at this time.

.LONG TERM...(Wednesday through Monday)
Issued at 356 AM EDT TUE JUL 25 2017

Overall, busy start to the middle of the work week, but then things
quiet down through the end of the week. A round or two of showers
and storms is possible on Wednesday as a cold front moves across the
area, a few storms could be strong. Also, ahead of this cold front,
strong and gusty southwest winds will create a moderate swim risk on
Wednesday for the northern shores of Lake Michigan. After the cold
front pushes across the area Wednesday night, there will be a slight
chance for showers as a shortwave digs south across the area on
Thursday, then things quiet down through the fist half of the

Wednesday, lingering warm air advection showers and thunderstorms
across the central and east will continue to push eastward
throughout the morning hours. During the afternoon as the cold front
continues to push east across Upper Michigan, another round of
showers and storms will be possible in the afternoon, especially
across the east and south central. While cloud cover from convection
earlier in the day will likely hinder the amount of diurnal
destabilization, it isn`t out of the question that a few storms
could be strong to marginally severe, especially with the main
shortwave trough progged to dig southeast across Lake Superior and
over eastern portions of the area. The SPC has kept us within the
marginal risk for severe storms, which in this case given the
uncertainty in how the atmosphere will recover after early morning
convection seems appropriate. Right now it looks like heavy rain and
perhaps some gusty winds will be the main threat with stronger
convection in the afternoon/evening. However, if the atmosphere can
recover, with freezing levels falling right along the cold front
hail would also be a concern with stronger storms.

Wednesday night into Thursday, the cold front will finally push south
of the area and the weather will quiet down. During the day on
Thursday, a stout, fast moving shortwave is progged to dig south
across the Western Great Lakes region. With this wave progged to
come through during peaking heating, it isn`t out of the question
that we see a few scattered rain showers develop across the west and
central; however, better chances look to be right along the
Wisconsin/Michigan border. With little moisture ahead of this wave,
do not expect precipitation to amount to much. Behind this
shortwave, high pressure will begin to settle into the region
Thursday night through much of the weekend. With ample insolation
each day, expect seasonable highs in the 70s and lower 80s. Low
temperatures should remain very comfortable as clear skies give way
to ample radiational cooling each night. Towards the end of the
weekend/beginning of next week another cold front is progged to push
through the region. Confidence in how precipitation chances will
play out along this front is low right now as models diverge in the
strength and timing of the main shortwave aloft.

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 141 PM EDT TUE JUL 25 2017

Attention is on a front and associated convection expected to move
through tonight into Wed. Timing, coverage, and intensity of
precipitation and CIG/VIS is uncertain. In addition, there could be
LLWS tonight, but it looks to be just below wind different
thresholds to include in the TAF.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 409 PM EDT TUE JUL 25 2017

Expect stronger wind gusts from the south to southwest of 20-25 kts
into Wednesday morning over eastern sections as a low pressure
trough crosses the region. Strongest winds look to occur late
tonight into Wed morning over far east. Winds rest of this week will
be 15 kts or less with exception of Thu aftn into Thu evening over
east when wind gusts from the NNW could reach over 20 kts for a

Upper Michigan...
Lake Superior...
Lake Michigan...


LONG TERM...Ritzman
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