Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 241819

Area Forecast Discussion
National Weather Service Marquette MI
219 PM EDT Sun Sep 24 2017

.SHORT TERM...(This evening through Monday)
Issued at 219 PM EDT SUN SEP 24 2017

Upper air pattern consists of a deep 500 mb trough over the Rockies
and a strong 500 mb ridge over the ern U.S. The trough will move
into the northern and central plains 00z Tue while the ridge moves
to New England and the lower Great Lakes. Deeper moisture and
dynamics slowly move into the western cwa on Monday. Cool down will
begin starting on Monday, but temperatures will still remain above
normal and a few more records could be broken for Mon especially in
areas that do not have very long climate records like our office
here with 56 years of weather records. Temperatures look to be their
warmest in the morning, and then winds off Lake Superior will cool
things down in the afternoon as lake breezes set up. Will keep
slight chance pops late tonight in the far west and then slowly
bring in chance pops into the west half of the cwa late Mon
afternoon. Could be possible to see some lake breeze convection
break out Mon afternoon across the central cwa.

.LONG TERM...(Monday through Saturday)
Issued at 411 AM EDT SUN SEP 24 2017

Monday through Tuesday night: As the surface low shifts from MN into
Ontario through this time period, expected a very slow moving cold
front to drift into the western U.P. Monday. The front will pick up
speed late Monday night into Tuesday ahead of the approaching deep
trough from the west. A continued very moist environment ahead of
the cold front and the initially very slow movement of the front
will allow for the potential of heavy rainfall across much of the
CWA. PWAT values are progged to be around 1.5 inches or roughly 200
percent of normal for this time of year. Widespread severe weather
is not expected with the frontal passage, so the heavier rain
potential will be the main threat for this time period. The area
that will likely see the greatest totals, up to an inch, will be
over the western portions of the U.P. where the front will progress
the slowest. Temperatures will continue to be above normal for both
Monday and Tuesday; however, the trend will be more toward normal
temperatures by Tuesday afternoon, coolest for western portions of
the Upper Peninsula.

Wednesday through Friday: A bit drier air will push into the area
for Wednesday, which should lead to mainly dry conditions across
much of the area under near normal temperatures in the upper 50s to
around 60. Wednesday night through Friday, models continue to have
differing solutions on how strong the next wave of energy will be as
it rotates into the Upper Great Lakes. The GFS is not as strong and
much quicker with move the wave through the area, while the EC is
much stronger and more persistent in keeping deep troughing across a
good portion of the eastern CONUS. The Canadian model shows a very
similar trend to the EC, which have both been showing a similar
setup over the past few model runs. This lends more credibility to
keeping cooler temperatures along with rain showers and increased
cloud cover across much of the area. The system forcing will
initially be the cause for rain showers; however, cooler air aloft,
associated with the trough, will allow 850mb temperatures to
potentially drop below zero by late Friday afternoon resulting in an
increased lake effect rain shower component through Friday night.
Outside of the rain shower potential, temperature will cool off
significantly from where they`ve been over the past couple days. In
fact most places will be near to below normal by the end of the work
week. High temperature will fall into the low to mid 50s by the ind
of the work week.

Rest of the extended: The trough will begin to progresses eastward
through Sunday, allowing for warming temperatures aloft along with
drier air to filter into the area. This should lead to a diminishing
trend in the rain shower potential along with a steady warming trend
toward the end of next weekend.

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1255 PM EDT SUN SEP 24 2017

VFR conditions are expected through the forecast period. A low level
jet developing above the nocturnal inversion will result in LLWS
late tonight at IWD and SAW.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 219 PM EDT SUN SEP 24 2017

Low to mid 60s dewpoints sliding across Lake Superior are expected
to linger into Tue bringing patchy to areas of fog across the lake.
Some of the fog could be locally dense at times. Expect winds to
generally be below 20 knots through the early part of the week under
a weak pressure gradient. However, as a cold front moves across Lake
Superior Tue night into Wed with colder air moving in, wind gusts
will increase to 20 to 30 knots. They will be in that range again
for Friday with cold air moving across the lake.

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


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