Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 180023

Area Forecast Discussion
National Weather Service Marquette MI
823 PM EDT Sat Jun 17 2017

.SHORT TERM...(This evening through Sunday)
Issued at 255 PM EDT SAT JUN 17 2017

Temps this afternoon have slowly warmed into the low/mid 70s across
the Keweenaw, with around 80 along the far Southern portions of the
U.P. Meanwhile further east, thicker cloud cover and onshore flow
has held temps in the mid/upr 60s. A weak convergence zone has been
able to lift parcels through a very moist and marginally unstable
environment and produced an area of showers with embedded thunder
for the far east CWFA. Meanwhile further west rain/storms early this
afternoon have struggled to become organized. WV/Visible satellite
imagery indicates a weak lobe of vorticity advecting southeast
towards the U.P. and could aid in vertical growth of cumulus;
however, with a cirrus shield lifting northeast from Northern Wisc,
it is possible this could counter any stronger growth and limit any
convection to isolated this afternoon.

With scattered showers and thunderstorms again progged for this
evening, the lack of mixing and uniform pressure gradient for
tonight, it appears the development of fog maybe ideal. Have
included the mention in the forecast, and could see a few sites dip
to less than 1 mile late this evening through daybreak Sun. Guidance
continues to indicate scattered showers persisting through the
overnight hours. With minimal omega/lift, expect smaller droplets
and not much rain through the overnight hours. Then for Sun,
guidance swings the broad surface low northeast across the eastern
U.P. There does appear to a dry slot lifting northeast by mid-
morning Sun, which may help to erode some of the precip shield over
central/eastern U.P. With considerable solar shielding during the
day Sun, and flow turning northwest, temps will struggle to warm
beyond the low/mid 60s west/central and upr 60s in the far east.

.LONG TERM...(Sunday night through Saturday)
Issued at 237 PM EDT SAT JUN 17 2017

Overall next week looks cooler compared to recently as northwest
flow will persist through the first half of the week, before
transitioning zonal flow. Temperatures will start off a few degrees
below normal, and then return to near normal through the end of the
week and into next weekend. There will be a few chances for showers
and periodic thunderstorms as a number of shortwaves dig and/or
traverse the Upper Great Lakes. Difficult to pinpoint exactly what
days with have the best precipitation chances towards the end of the
week given the differences in speed and strength of shortwave activity
among the medium range models.

Monday and Tuesday will bit noticeably cooler as longwave troughing
moves overhead with northwest flow develops across the Upper Great
Lakes and cooler 850mb dropping down from Canada. On both days,
there will be chance for showers and perhaps a few rumbles of
thunder. On Monday these showers will be mainly diurnally driven
given the cooler temperatures aloft. Monday night through Tuesday,
there will be another chance for showers as a more potent shortwave
digs south across the area and weak warm air advection lifts into
Upper Michigan. Model trends suggest a more southern track may be
favored with this shortwave; therefore, thinking the best chances
for additional precipitation should stay across the southern
portions of the area. Depending on the strength of this wave, if mid-
level lapse rates can steepen enough, wouldn`t be surprised if
locations that see precipitation hear a few rumbles of thunder.
Although, forecast soundings show very skinny CAPE profiles aloft.

Wednesday through Thursday, a shortwave will cross the northern
Rockies and quickly dig towards the Upper Great Lakes region. As
warm air advection increases ahead of this shortwave, temperatures
will return to near normal. There are some discrepancies among the
medium range models in regards to the strength and speed of the
shortwave and resulting surface features. Therefore, it is hard to
pinpoint when precipitation will begin to work its way into Upper
Michigan. However, confidence is highest that precipitation should
begin to move into the west late Wednesday afternoon and then
continue to push east into Thursday. Depending on the speed of the
wave, precipitation may linger into Thursday.

Towards the end of the week, another shortwave embedded within zonal
flow will track across the northern CONUS will send a cold front
across the area. It`s too early to tell speed/timing of this frontal
boundary so temperature wise it is hard to pinpoint how warm we will
get head of the front. However, 850mb temperatures don`t look
terribly impressive across the warm sector, so at this point only
expect temperatures to be seasonable. As the front pushes east
across Upper Michigan, another round of showers and maybe some
thunderstorms will be possible. Next weekend, the upper-air pattern
gets diverges among the medium range models as differences are
further amplified, but with hints of lingering shortwave activity,
we may see additional precipitation towards the end of the weekend
with near normal or slightly below normal temperatures.

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 802 PM EDT SAT JUN 17 2017

Showers will continue tonight becoming more numerous late evening
into the overnight hours as another disturbance moves into the
area. VFR conditions will lower to IFR/LIFR overnight in
fog/low stratus as winds become northerly/onshore from Lake
Superior on backside of developing low pressure. Conditions will
be slow to improve on Sunday but should reach high end IFR to low
end MVFR by late afternoon as stratus slowly lifts. &&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 255 PM EDT SAT JUN 17 2017

With warm/moist air lifting northeast over the lake, some patchy fog
is expected to persist. With a low pressure system arriving Sun,
winds will freshen up from the northwest and should help to
eliminate any lingering marine fog by midday Sun. Winds will
generally remain below 20kt; however, with winds shifting to the
northwest Sun this could help build waves along the Lake Superior

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


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