Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 221151
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
751 AM EDT Sun Jul 22 2018

.SHORT TERM...(Today and tonight)
Issued at 554 AM EDT SUN JUL 22 2018

Water vapor imagery and RAP analysis show a large mid-level low
centered over Ohio with Upper MI on the nw periphery of the
circulation. Upstream, a trof is swinging thru
Alberta/Saskatchewan/northern Rockies with a ridge btwn this trof
and the Ohio low. Area of shra that was spreading w across eastern
Upper MI during the evening has largely dissipated. Only isolated
-shra remain across parts of s central Upper MI. Meanwhile,
persistent -dz has developed across the n central, Marquette County
in particular.

The -dz over n central Upper MI may push into parts of western Upper
MI over the next several hrs. Otherwise, expect -dz/isold -shra to
end during the morning as there will be little forcing to support
pcpn. Can`t totally rule out an isold -shra over the se fcst area
this aftn, particularly if there is enough insolation to generate
some instability. Potential appears quite low at this time, so a dry
fcst was carried thru the aftn. Otherwise, shortwave currently
rotating toward the Lower Lakes will swing toward the Upper Lakes
tonight, but it will encounter the upstream ridge pushing into the
Upper Lakes in response to the trof progressing into s central
Canada/Dakotas. As a result, while -shra may spread into far eastern
Upper MI, not expecting shra associated with the wave to reach the
fcst area tonight. Expect some clearing today, especially across the
w half of the fcst area. This clearing may then support at least
patchy fog development tonight under light/calm wind with temps
likely falling well past the crossover temp/minimum aftn dwpt.
Expect highs today in the 70s, 60s at most locations along Lake
Superior. Lows tonight should fall into the 40s over the interior w
with 50s the rule elsewhere.

Steady/rather brisk n to ne winds over the e half of Lake Superior
will generate waves upwards of 3.5ft, warranting a mdt swim risk
today for the beaches of Marquette/Alger counties.

.LONG TERM...(Monday through Saturday)
Issued at 343 AM EDT SUN JUL 22 2018

Overall, temperatures are expected to remain fairly seasonable
through this week. The warmest conditions are expected early to mid
week, but then we will see a trend towards cooler conditions later
in the week as another slow moving system rotates across the Great
Lakes region. From a wind perspective, not looking terribly windy
through the first half of the week, but as low pressure becomes
established and tracks just north of Lake Superior later in the
week, an enhanced pressure gradient will allow for gustier winds at
times.

High pressure will grab hold of the region through the middle of the
week; however, the ample sunshine will allow for temperatures to
warm nicely into the upper 70s and lower 80s each day. This will
favor the development of thermal troughing across the Upper
Peninsula. As a subtle shortwave tracks east across the area, there
will be a chance for thunderstorms Tuesday afternoon mainly in
central portions of the area. Right now, the deep layer shear looks
rather weak, around 15-20 knots. Therefore, expect convection to
remain rather pulsey if updrafts can sustain themselves. Otherwise,
the next best chance for showers and thunderstorms looks to arrive
on Wednesday as a cold front pushes eastward across the Upper Great
Lakes. Depending on how much instability can develop this far north,
with the deep layer shear looks better convection will have the
ability to remain more organized.

Followed closely behind this cold front, the main slow-moving upper
level low is progged to track across the region. This will favor
increased chances for precipitation towards the end of the week.
That far out, confidence is low in how things will evolve and who
will see the better chances for additional precipitation. Next
weekend, medium-range guidance are all showing additional shortwave
activity behind the exiting upper-level low. Therefore, expect
additional chances for precipitation next weekend as cooler air
aloft and additional synoptic-scale lift looks to support diurnally
driven convection.
&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 751 AM EDT SUN JUL 22 2018

VFR conditions are expected to continue at KCMX thru this fcst
period. Meanwhile, upsloping low-level moist air has led to LIFR
conditions at KIWD/KSAW. Daytime heating should lead to
lifting/erosion of this stratus over the next few hrs with both
terminals improving to VFR by aftn. VFR conditions will then
continue thru the remainder of the fcst period. However, shallow
radiation fog may develop at KIWD later tonight.
&&

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 554 AM EDT SUN JUL 22 2018

Across eastern Lake Superior, expect winds of 10-20kt thru this
morning before gradually diminishing during the aftn. High obs
platforms may see a few gusts to 25kt this morning. Some fog is also
expected over eastern Lake Superior. Winds will be lighter over the
western part of the lake, mostly 5-15kt. Winds will diminish further
across the entire lake tonight/Mon as a high pres ridge shifts to
the Upper Lakes. Winds will be mostly under 10kt on Mon. Winds
should then remain under 15kt thru Tue night. Low pres organizing
over northern Ontario Wed/Thu will then lead to increasing westerly
winds, especially by Thu. Gusts may reach the 20-25kt range.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...Rolfson
LONG TERM...Ritzman
AVIATION...Rolfson
MARINE...Rolfson



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