Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 191737

Area Forecast Discussion
National Weather Service Marquette MI
137 PM EDT Wed Jul 19 2017

.SHORT TERM...(Today and tonight)
Issued at 523 AM EDT WED JUL 19 2017

A fairly vigorous shortwave and associated 100 kt 3h jet max has
initiated convection over western and central MT early this morning.
This shortwave will be the feature to watch as it moves across the
northern CONUS in a rapid zonal flow today and into the Upper Great
Lakes region tonight. The big fcst question in the short term will
be determining whether this feature will bring any convection into
Upper Michigan tonight. In the near term...The sfc cold front which
brought the showers and storms to Upper Mi yesterday has passed well
se of the region, and sfc ridging moving in behind the front has
resulted in clearing skies and dry conditions overnight/early this
morning. Lingering low-level moisture from the recent rainfall has
also resulted in patchy fog at some locations.

Today: Models indicate sfc ridging will dominate keeping conditions
dry today under mostly sunny skies. Model soundings show mixing near
800 mb should result in high temps mainly in the lower to mid 80s
over the western interior with lake breeze circulations keeping
temps in the 70s closer to the Great Lakes shorelines and east.

Tonight: Northern Rockies shortwave is progged to move through the
Upper Midwest/Upper Great Lakes region tonight. Models fairly
consistent showing strongest convection developing over the Northern
Plains this afternoon and then following sse along frontal
boundary/instability gradient over southern MN and southern/central
WI where dewpoints in the lower 70s will lead to MUCAPEs of 2000-
3500 j/kg. Despite best moisture/instability staying well south,
it still looks like there will be enough forcing with the shortwave
to potentially form showers over Upper Mi late evening/overnight.
Instability gradient should be far enough south to prohibit
thunder...except far south central locations could see an isolated
t-storm where mid-level lapse rates wl exceed 7C/km.

.LONG TERM...(Thursday through Tuesday)
Issued at 507 AM EDT WED JUL 19 2017

Models suggest that a brief transition to zonal flow atop a
mid/upper level ridge over the lower MS valley will give way to
some amplification this weekend as the ridge shifts westward
favoring nw flow into the Great Lakes. Temps will remain at or
above normal into the weekend and then drop below normal from Sun-

Thursday, any lingering shra brushing mainly the srn cwa associated
with the shrtwv and area of convection sliding through WI will
depart during the morning. With plenty of afternoon sunshine, temps
will climb into the mid and upper 70s near the Great Lakes to the
lower 80s inland.

Friday, the main sfc-850 mb front remains far enough to the south so
that the next stronger shortwave and associated area of convection
should remain over WI with only lighter pcpn on the nrn fringe
possibly brushing the the srn cwa from the late afternoon into the

Sat-Sun, as the mid/upper level flow becomes more northwesterly, a
stronger shortwave trough is expected to drop from srn Manitoba into
the nrn Great Lakes. The ECMWF remained slightly faster with this
feature compared to the GFS and especially the GEM.
Although there is still some timing uncertainty, the initial band of
showers with WAA and 700-300mb qvector conv ahead of the shrtwv is
expected to move in from the west from Saturday afternoon into
Saturday evening. Shower chances will persist through most of Sunday
into Sunday night until the shrtwv slides off to the east with some
lingering light wrap-around pcpn possible into early Monday.

Mon-Tue, although the slower GFS/GEM would keep some light pcpn
going, model trends and the ECMWF suggest that mainly dry weather
will prevail. High pressure with cooler dry air will build into the
region with pleasant conditions. Highs will range from the upper 60s
north to the lower 70s south Monday with slightly warmer conditions

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 136 PM EDT WED JUL 19 2017

Confidence in precipitation and lower ceilings reaching KSAW/KIWD
late tonight is not high right now as an large complex of storms is
progged to develop well south of the area and should rob the area
of deeper moisture this far north. Therefore, have opted to not
go terribly low in ceilings and only include mentions of VCSH for
now. If any precipitation does make it into the area, KIWD/KSAW
will have the highest likelihood of seeing rain showers and
perhaps a rumble of thunder.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 523 AM EDT WED JUL 19 2017

High pressure will generally remain in control across the across the
region today thru Saturday keeping winds light, less than 15 knots
across the lake. Towards the later half of the weekend, depending on
the track of another storm system moving across the region winds
could increase to around 20 knots across the lake on Sunday.

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


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