Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 251138

Area Forecast Discussion
National Weather Service Marquette MI
738 AM EDT MON JUL 25 2016

.SHORT TERM...(Today and tonight)
Issued at 448 AM EDT MON JUL 25 2016

Water vapor imagery and RAP analysis show a trof over northern
Ontario and the western Great Lakes. Within the trof, one shortwave
is currently moving across Upper MI while another is swinging thru
northern Ontario. The former is not associated with any pcpn or any
cloud cover for that matter. The latter is producing an area of
clouds extending s toward Isle Royale as well as some -shra to the n
of Thunder Bay. Othewise, clear skies dominate from Upper MI w into
the northern Plains where sfc high pres is located early this

With sfc high pres drifting eastward, the short term portion of the
fcst will feature dry weather. While the day will begin with clear
skies, daytime heating working on boundary layer moisture will
generate sct cu this morning that will then gradually fade away from
w to e during the aftn. Fcst soundings suggest high temps will
generally be in the upper 70s to low 80s for much of the area.
Should be a little warmer over the s central due to downsloping wnw
winds and a little cooler along Lake Superior over the w and also
from Pictured Rocks eastward. Breezy nw winds will build sufficient
waves for a mdt swim risk for the Lake Superior beaches of Alger
County today.

Tonight, center of sfc high pres will move to IA/sw WI/northern IL.
Meanwhile, shortwave currently over Saskatchewan will reach northern
Ontario. Associated cold front will extend from northern Ontario
across nw MN into ND at 12z Tue. Some drying of the boundary layer
today combined with relatively light winds and clear skies for much,
if not all, of the night should allow temps tonight to fall into the
mid 50s in the interior. May see some lower 50s at traditional cold
spots. Winds stirring closer to Lake Superior will keep mins no
lower than the low/mid 60s. In response to the shortwave moving to
northern Ontario, models show nose of 40kt low-level jet becoming
aimed toward western Lake Superior late tonight. With several
hundred j/kg of cape for parcels lifted from 850mb per NAM and
regional Canadian model, not out of the question that convection
that should develop in northern MN later tonight may streak out
toward far western Upper MI shortly after sunrise Tue. While this
fcst issuance retains dry weather thru 12z Tue, it will be something
to re-examine in later forecast updates.

.LONG TERM...(Tuesday through Sunday)
Issued at 424 AM EDT MON JUL 25 2016

Tuesday through Wednesday night: A cold front is progged to sag
southward from Canada, Tuesday morning, into the Upper Great Lakes
Region Tuesday night as surface high pressure slides to the east.
Southerly flow on the back side of the high will help to increase
moisture into the area. This, along with forcing along and ahead of
the front, will provide chances of showers and thunderstorms for
most of the CWA through that time period. As the weak cold front
slides to the south of the area Wednesday and Wednesday night, the
better chances for showers and thunderstorms will also slide south
and linger over northern WI and possibly along the Upper MI/ WI
border. MUCAPE values are progged to be between 1000-1500 J/kg
Tuesday afternoon/evening and around 500-1000 J/kg Wednesday
afternoon/evening. The severe weather potential looks low at this
point, through this time period, as the system will lack any major
dynamical support, keeping shear values around or below 25-30 knots.
The storm mode would likely be more of a pulse thunderstorm mode
during the afternoon/evening hours on both Wednesday and Thursday.
Some of the the storms Tuesday afternoon/evening may pulse up and
become strong for a brief period of time, but organized severe
weather is not expected. The main threat from any of the stronger
storms would be small hail and gusty winds.

Thursday through Friday night: High pressure and dry air is progged
to slide into the area from Canada by Thursday afternoon and then
linger through this time period. Aloft, the Upper Great Lakes region
will be under a slight troughing pattern to near zonal flow. This
flow along with fairly dry air in place will keep the bulk of the
precipitation to the south of the U.P., while also helping to keep
temperatures closer to slightly below normal for this time of year.
Normal highs are right around 77 while normal lows are around 55.
There is a 500mb shortwave that is progged to slide just south of
the U.P., mainly across WI, Thursday afternoon and evening. At this
point, the main impact for the U.P. would be an increase in cloud
cover along the WI border with perhaps a slight chance of showers
for the south half of the U.P.

Saturday through the extended: The aforementioned high pressure
system will slide to the east of the area through this time period.
As this happens, warmer and more moist, southerly flow will return
to the Upper Great Lakes region. Aloft, it looks as if there may be
a couple shortwaves that slide across the area, bringing small
chances for showers and thunderstorms.  Exact details are tough to
pin down this far out, but it does look like the CWA could see
showers and thunderstorms, with the best chances occurring during
the afternoon hours each day through this time period. Confidence is
low enough at this point to stick with only low chance pops.

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 738 AM EDT MON JUL 25 2016

Vfr conditions will prevail at KIWD/KCMX/KSAW thru this fcst period.
Winds will be gusty during the day, especially at KCMX where gusts
will be up to 25kt. Winds will diminish quickly this evening.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 448 AM EDT MON JUL 25 2016

With low pres near James Bay and high pres over the northern Plains,
westerly winds will gust as high as 20-25kt at times today on Lake
Superior. These stronger winds will diminish this evening as pres
gradient weakens. Winds for the remainder of the fcst period will be
mostly 15kt or less.

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


SHORT TERM...Rolfson
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