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Area forecast discussion
National Weather Service Marquette Michigan
730 PM EDT Sat Jul 21 2018

Short term...(this evening through sunday)
issued at 354 PM EDT Sat Jul 21 2018

The main weather impacts in the short-term will be continued rain
showers through tonight along with a moderate to high swim risk for
the Lake Superior coast of Marquette and Alger counties.

The broad surface low and upper-level low over lower Michigan will
continue to shift slowly off to the east of the area tonight into
Sunday. Initially, late this afternoon through tonight, the low will
be close enough to the u.P. To bring continued rain showers sliding
in from east to west across the area. The most concentrated area of
rain showers will be over the eastern u.P. Where the better forcing
from a shortwave will be located. It's not out of the question that
a could rumbles of thunder may occur over the eastern portions of
the u.P. Continued upslope flow over central Upper Michigan will
help to also keep some concentrated light rain shower or drizzle in
place through much of the night. During the day Sunday, the low will
depart far enough east that drier air and high pressure can filter
in from the north and east. This will allow for some afternoon
sunshine; however, clouds may linger a bit longer over the north-
central u.P. As moist upslope flow takes a bit longer to decrease.
Lows tonight will be kept up a bit by the increased cloud cover,
with most locations staying in the 50s to low 60s. Highs Sunday will
be in the 70s and 80s, coolest downwind of Lake Superior.

A moderate to high swim risk over Marquette and Alger counties on
can be expected tonight into Sunday. While beach hazard statements
are not issued for the MQT County Warning Area at night, it is possible that one
will be needed Sunday as skies begin to clear and the rain departs
to the east.

Long term...(sunday night through saturday)
issued at 424 PM EDT Sat Jul 21 2018

Models suggest that a slowly progressive pattern will prevail as a
mid/upper level low over Saskatchewan Sunday wobbles eastward
into nrn Ontario by Wednesday. The low will finally open up and
lift into Quebec by late Friday or Saturday. This pattern, with
mainly westerly low level flow, will bring temperatures near
seasonal averages with highs in the 70s to around 80 and lows in
the 50s.

Sunday night, mid level and sfc ridging will build into the wrn
Great Lakes with clearing over the eastern half of Upper Michigan.
Favorable radiational cooling over the west will allow temps to drop
to around 50 while temps remain closer to 60 east and along the
Great Lakes.

Monday and Tuesday, a shortwave and associated weak cold front
moving out of the northern plains could bring some isolated showers
and maybe a thunderstorm toward western Upper Michigan during the
late afternoon/evening. However, moisture transport and instability
will likely be limited as forcing weakens along/ahead the front as
it moves into the northern Great Lakes so that no pcpn is expected
over Upper Michigan. Another shortwave moving through the area could
produce a few isolated showers/T-storms Tue afternoon as diurnal
instability builds.

Tuesday night into Wednesday, as the mid-level low from Canada
sinks south the next significant shortwave and sfc front is
expected to move into the region by Wed bringing another chance of
pcpn. With limited moisture inflow, only lighter rainfall amounts
would be expected with mainly scattered coverage. Dewpoints to
around 60 and fcst cape values would support thunderstorms during
peak heating as highs climb into the upper 70s to lower 80s.

Thu-Sat, cyclonic mid-level flow through the upper Great Lakes from
trough/mid-level low centered over northern Ontario will bring
additional weak shortwaves through the area producing periodic light
showers. High temperatures will trend slightly cooler than normal,
mainly in the 70s.

Aviation...(for the 00z tafs through 00z Sunday evening)
issued at 729 PM EDT Sat Jul 21 2018

Challenging taf forecast, especially for iwd and saw with northerly
to northeasterly flow into these two taf sites both having an
upslope component and advecting the marine layer onshore. IFR to
intermittent LIFR conditions can be expected here through tomorrow
morning due to both cig and vis restrictions, with even a period of
vlifr possible at saw overnight. Conversely, a northeasterly wind at
cmx means generally downsloping winds and no immediate trajectory
over water, so have kept them in VFR throughout the taf period.
Conditions begin to improve at all sites tomorrow afternoon as this
pesky low pressure system finally departs to the east.

Marine...(for the 4 PM Lake Superior forecast issuance)
issued at 354 PM EDT Sat Jul 21 2018

Expect winds generally 15-20 knots through tonight as a low pressure
system slowly departs the area to the east. Rainfall across Lake
Superior has resulted in areas of fog today, which will linger
through Sunday morning before drier air pushes into the area. Some
fog could be locally dense. High pressure building in Sunday through
early next week will result in winds staying mostly 15 knots or

MQT watches/warnings/advisories...
Upper Michigan...
Lake Superior...
Lake Michigan...


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