Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 281918

Area Forecast Discussion
National Weather Service Marquette MI
318 PM EDT Tue Mar 28 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 304 PM EDT TUE MAR 28 2017

12Z raobs/latest wv imagery and RAP analysis show a shrtwv rdg in
the nrn branch flow over scentral Canada that is supporting a sfc hi
pres over nrn Manitoba expanding into Ontario. There is a weak
shrtwv crossing the Upr Lks, but dryness of the mid lvls shown on
local 12Z raobs is allowing for only some patchy mid/hi clds over
mainly the nrn cwa. Area of fog and lo cld that was over the ern cwa
this mrng with llvl mstr trapped under lo subsidence invrn base as
depicted on the 12Z APX raob has dsptd as the incrsgly acyc llvl nne
flow associated with the expanding sfc hi pres rdg is advecting some
drier air into the area in the presence of daytime heating, which
has aided in mixing out this mstr. The lo cld has been most
persistent near Lk MI and over far ern Lk Sup, where the cooling
influence of the waters have slowed daytime heating/mixing out of
the lo cld. Away fm this area, temps have climbed into the 50s away
fm the cooling influence of Lk Sup. There is quite a bit of lo cld
farther n over Ontario under area of colder near sfc temps.

Main fcst concerns in the short term are lo cld trends/temps. Large
scale subsidence under shrtwv rdging/expanding Hudson Bay hi pres wl
tend to suppress the mid/hi cld and bring dry wx.

Tngt...The Hudson Bay hi pres center is fcst to build slowly to the
se and be centered over far nw Ontario just to the w of James Bay by
12Z Wed. Upr MI wl be under the influence of the acyc, slowly
veering llvl flow toward the ene. Even though the diffluent/acyc
nature of this wind would tend to break up lo clds, concern is lo
clds lingering over ern Lk Sup and spreading s thru Ontario wl
redevelop over mainly the ncentral cwa as the expected ene winds
upslope into that area in the presence of nocturnal cooling. Expect
the lowest min temps over the interior w, where the llvl flow wl
downslope and allow for moclr skies. Not out of the question temps
in this area could fall as lo as the upper teens.

Wed...Upr MI wl remain under the influence of Hudson Bay hi pres
moving slowly to the e to over James Bay by 00Z Thu and slowly
veering llvl flow to the e. Expect any lo clds in the mrng over
mainly the ncentral to mix out with daytime heating. Since h85 temps
wl be 2-3C cooler than tday and hi clds wl be on the incrs, expect
Wed max temps to be lower than today, reaching to near 50 over the
interior w with some downsloping away fm lk moderation.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 318 PM EDT TUE MAR 28 2017

The extended looks to be fairly quiet overall with the main focus on
low pressure sliding to the south of the U.P. Thursday into Thursday
night and another low pressure trough sliding across the area
Saturday into Saturday night. A more widespread precipitation event
is possible for early next week, Monday night into Tuesday.
Otherwise, expect above normal temperatures through the extended
with highs in the 40s to around 50 and overnight lows in the mid to
upper 20s.

Thursday and Thursday night: An area of low pressure sliding across
the mid Mississippi Valley is progged to lift slowly through the
Ohio River Valley through this time period. At the same time, a
Hudson Bay high pressure system will remain near stationary or slide
very slowly off to the east. The northern fringes of the moisture
associated with the low will try to work into the U.P.; however, the
northward extent is expected to be limited as the flow around the
high pressure system will be very dry. The easterly winds will
steadily pump dry air in to offset the approaching moisture. This
continues the trend seen over the past couple days. At this point,
will continue pushing the pops down across the south central U.P.
and east along Lake Michigan. If precipitation does occur, it will
mostly likely be in the form of light snow or rain/snow mix. Most of
the sounding looks to be below freezing with some ice crystals in
the layer; however, the lower levels are fairly dry for Thursday
afternoon into Thursday evening. Wet bulb temperatures in the dry
layer would suggest cooling to or just below freezing through that
time period, keeping the precip in the form of mainly light snow.
The rest of the area is only expected to see an increase in cloud
cover through this time period.

Friday through Saturday night: Drier air and a weak ridge will slide
through the area Friday into Friday night allowing for mostly clear
skies across the U.P. The next chance of precipitation will be
Saturday through Saturday night as a quick moving surface trough and
upper-level trough slide through the area. At this point, not
expecting an all day, widepsread rainfall, but at least expecting a
quick moving shot at light rain. It may actually cool off enough at
Saturday night for some snow to mix in, but not expecting much for

Monday night into Tuesday: A broad area of low pressure is progged
to slide into the Upper Great Lakes region, bringing widespread
precipitation. There has been some variance in the models for that
time period, as expected with it being toward the end of the
forecast period, but the latest trends have the area under an
unsettled weather pattern for that time period. The Canadian is
pulling back a bit; however, with little to no precipitation making
into the U.P. At this point, will stick with a blend of the models,
painting precipitation across the area. 850mb temperatures, as well
as much of the soundings, are progged to be a few degrees above
zero, which would keep the precipitation mainly in the form of rain
across the area. Stay tuned as there is still plenty of variability
in the models.

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 138 PM EDT TUE MAR 28 2017

Expect VFR conditions and light winds to prevail at all the TAF
sites this fcst period. However, shallow llvl moisture over Lake
Superior could lead to stratus/LIFR conditions tonight at KSAW under
light upslope ne winds. Right now, potential appears very low, but
did include a mention of sct clouds at 500ft to reflect this
possibility. Any fog and lo clds will burn off by late morning.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 304 PM EDT TUE MAR 28 2017
With no significant weather systems affecting the Upper Great Lakes
for the rest of this week, winds will mostly be under 20kt this
forecast period. The stronger winds (gusting to around 20kt) will
occur tonight thru Wed night under slightly tighter pres gradient
btwn Hudson Bay hi pres and lo pres tracking from the southern
Plains toward the Ohio River Valley.

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


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