Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 191915

Area Forecast Discussion
National Weather Service Marquette MI
315 PM EDT Sat Aug 19 2017

.SHORT TERM...(Today and tonight)
Issued at 256 AM EDT SAT AUG 19 2017

An area of scattered showers with some isolated thunder moved into
far northwest portions of Upper Michigan this morning as a
shortwave continued to move across western Lake Superior. Through
the morning hours, these scattered showers and thunderstorms will
continue to push southeast into central portions of Upper
Michigan, primarily the north central, before diminishing over the
next few hours. Elsewhere, lingering cloud cover was observed
early this morning.

Later today, as the main upper-level wave lifts out of the region,
cloud cover will gradually start to wane from west to east. With
increasing insolation and a somewhat dry air mass overhead, expect
temperatures to warm nicely into upper 70s and low 80s. Locations
that see temperatures climb into the low 80s will likely be confined
to areas of better downsloping. Given the increased insolation, lake
breeze boundaries are expected to develop and push inland through
the afternoon and evening hours. Increased convergence along the
lake breeze boundaries and area of more substantial terrain, and
along lake breeze interactions, will allow for afternoon showers and
thunderstorms to develop. While there will be a small chance that a
few of these storms may develop across the north central portions of
the area, the main focus should remain where the Lake Superior and
Michigan breeze converge across the central and east. A weak PV
anomaly/shortwave is progged to clip the area this afternoon and
should also provide some additional lift for afternoon convection.
It will also help increase the amount of deep-layer shear as well,
with 0-6km shear increasing to around 30 to 40 knots by the mid-
afternoon hours. Along these lake breeze boundaries, low-level
moisture is progged to pool with dew points climbing into the low
60s. Therefore, it looks like around 1000 to possibly upwards of
1500 J/kg of MUCAPE will develop. These ingredients should allow for
some storms to remain organized, and possibly strong at times,
especially considering the shear orientation will remain quasi-
perpendicular to where the lake breezes are progged to interact.

Tonight, any lingering showers and thunderstorms across the south
central and east will push out over Lake Michigan. Temperatures will
remain mild as winds become southwesterly ahead of an approaching
cold front.

.LONG TERM...(Sunday night through Saturday)
Issued at 315 PM EDT SAT AUG 19 2017

A band of showers and thunderstorms will develop over west central
Upper Michigan along an advancing cold front and upper trough Sunday
afternoon. These showers and thunderstorms will progress east
southeastward across the remainder of the U.P. Sunday evening.

Trends continue to suggest Monday will now be drier with a more
optimistic cloud cover forecast now expected through the early
afternoon hours during the eclipse. Another shortwave trough will
move out of the northern Plains by late in the day Monday producing
a surface wave along the frontal boundary south of the area over
Wisconsin. Precipitation shield from this feature will remain mainly
south of the U.P. but may graze southern sections Monday night into
early Tuesday.

A reinforcing push of cooler air will push into the Upper Lakes by
late in the day Tuesday with an extended period of cool but pleasant
weather expected through the remainder of the week into next
weekend. It could even be cool enough Wednesday night into Thursday
for some patchy frost across the interior west. Temperatures will
slowly modify to near normal by next weekend.

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 141 PM EDT SAT AUG 19 2017

VFR conditions expected at each TAF site through this TAF issuance.
The only TAF site that may see some issues this afternoon will be
KSAW as lake breezes slide through, causing winds to shift and
possible touching off a couple showers. Otherwise, no major issues

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 256 AM EDT SAT AUG 19 2017

Winds are expected to remain 10 to 20 knots through the weekend.
Early next week, winds will relax to around or less than 15 knots.
Tuesday and Wednesday as the surface pressure gradient is progged to
increase across the area, winds will pick up to around 20 knots.
Then towards the latter half of the week, high pressure will take
over and winds are expected to remain under 15 knots.

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


SHORT TERM...Ritzman
MARINE...Ritzman is the U.S. government's official web portal to all federal, state and local government web resources and services.