Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 162041

Area Forecast Discussion
National Weather Service Marquette MI
341 PM EST Thu Feb 16 2017

.SHORT TERM...(This evening through Friday)
Issued at 340 PM EST THU FEB 16 2017

12Z raobs/latest wv imagery and RAP analysis show a confluent nw
flow aloft over the Upr Great Lks btwn deep closed lo over New
England and an upr rdg over the Plains. At the sfc, hi pres rdg axis
extending fm near Hudson Bay to Lower MI is moving slowly to the e.
Les that was ongoing this mrng over the ern cwa has ended with the
passage of the sfc rdg axis, but plenty of mainly mid/hi clds are
present over the cwa associated with general waa on the wrn flank of
the slowly departing hi pres rdg. Local radars show a band of hier
returns extending fm sw Ontario acrs wrn Lk Sup to over wrn Upr MI
to the ne of sharp h85 warm fnt separating 12Z h85 temps as hi as
10C at The Pas Manitoba and 13C at Aberdeen SDakota/Bismarck fm -7C
at YPL and GRB. Although the dry lyr shown btwn h85-6 on the 12Z INL
raob as well as some very dry near sfc air over the cwa are limiting
the coverage of the hier returns/pcpn reaching the grnd, some sites
near Thunder Bay have reported some lgt sn/flurries under persistent
lo clds with upslope sse flow off Lk Sup. Farther upstream in the
Plains on the warm side of the sfc warm fnt, temps have surged well
into the 40s/50s.

Main fcst concerns in the short term focus on cld trends/temps.

Late today/tngt...Axis of some sharper isentropic ascent/hier rh
depicted on the 290K sfc /h8-7/ extending thru the central cwa late
this aftn is fcst to drift slowly to the e ahead of aprchg h85 warm
fnt. Band of thicker mid clds/perhaps some flurries associated with
this sharper waa wl shift to the e and exit the ern cwa late tngt.
Since the llvl flow is fcst to remain more sse ahead of the aprchg
sfc warm fnt most of the ngt, concerned some lo clds may linger,
especially in areas that would experience upslope flow off Lk MI as
is obsvd right now near Thunder Bay with upsloping off Lk Sup. With
a steady s wind fcst at h925 and some clds, expect a much warmer
overngt than early this mrng.

Fri...As the sfc warm fnt shifts slowly to the ene, expect lingering
lo clds to give way to more sunshine w-e. Over the far w fm IWD to
Ontonagon, max temps wl likely reach at least 50 with more sunshine,
a downslope wind component, and under h85 temps fcst to climb as hi
as 12C. But over the e with more persistent cld cover and later
arrival of the sfc warm fnt, the mercury may have a hard time rising
much above the freezing mark.

.LONG TERM...(Friday through Wednesday)
Issued at 321 AM EST THU FEB 16 2017

Upper air pattern consists of a 500 mb ridge in the upper Great
Lakes 12z Fri with a shortwave moving into the area Fri night
through Sat morning. Behind this shortwave...ridging builds back
into the area. Quiet, dry and warm weather will continue through
this forecast period.

In the extended, GFS and ECMWF show a 500 mb ridge over the central
U.S. 12z Sun. This ridge amplifies as it moves into the upper Great
Lakes 12z Mon. A shortwave moves through the area 12z Tue with more
troughing for Wed. The warm air associated with the ridge gets
pushed further south with time as colder air makes a return to the
area on Thu. We are on the southern edge of the colder airmass as a
cold front moves through on Wed. Much above normal temperatures will
cool to slightly above normal by Thu. Looks warm enough that most
pcpn will be rain. Late Tue night and early Wed morning, looks like
there could be a little freezing rain possibility with temperatures
slightly below freezing.

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1231 PM EST THU FEB 16 2017

Although there wl be considerable mid/hi clds into this evng ahead
of an aprchg warm fnt, expect VFR conditions to dominate. But later
tngt, an upslope sse wind off Lk MI wl probably bring some lo clds
to SAW as the aprchg warm frontal invrn lowers. These clds are
likely to linger thru Fri mrng. Downslope nature of the sly flow at
CMX and IWD wl limit the lo cld potential there, so fcst VFR
conditions to predominate there.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 340 PM EST THU FEB 16 2017

Expect ssw winds up to 25 kts under sharp pres gradient on the
wester flank of retreating hi pres to prevail thru Fri night. Then
following the passage of a lo pres thru nw Ontario and accompanying
lo pres trof over Lake Superior, winds will shift to the wnw and
increase up to 25-30 kts on Sat/Sat night. These stronger winds will
diminish as early as Sat night over the west with this trend
continuing thru Sun over the entire lake ahead of an approaching hi
pres ridge. After this hi pres ridge shifts to the e on Sun night, e
veering s winds will increase up to 30 kts on Mon under the
sharpening pres gradient between the departing ridge and a lo pres
moving ne thru the Plains. Expect winds to shift to the w on Tue
following the exit of the lo pres into Ontario/passage of associated
cool front. Since a trailing hi pres will quickly approach and
weaken the pres gradient, wind speeds should diminish steadily on

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


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