Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 180833

Area Forecast Discussion
National Weather Service Marquette MI
333 AM EST Sat Feb 18 2017

.SHORT TERM...(Today and tonight)
Issued at 332 AM EST SAT FEB 18 2017

Nothing tricky in the short term, just fine-tuning temps and winds.

W winds will keep the Keweenaw and shoreline areas exposed to W
winds cooler today, with the warmest temps expected over the central
U.P.. Should see temps up to 58F over the south central today, which
should be enough to break a couple or more high temperature records.
Lows tonight will be in the uppers 20s to low 30s.

.LONG TERM...(Saturday night through Friday)
Issued at 259 PM EST FRI FEB 17 2017

With a mean wrn trof/ern rdg upr pattern dominating in the medium/
extended range, a flow of Pacific air wl result in a period of well
above normal temps for Upr MI. There wl be several disturbances
lifting out of the wrn trof and impacting the Upr Lks as well during
this time, so overall pcpn should run above normal. The first of
these pcpn events later on Mon into Tue wl drop all rain, which
could be locally heavy. While limited mstr inflow wl restrict pcpn
associated with the passage of the next disturbance at mid week, the
strong disturbance/deep lo pres that is more likely to impact the
area at the end of the week could bring another round of heavy
mixed pcpn.

Sat ngt thru Sun ngt...Upr MI wl be dominated by a bldg upr rdg/
deep dry air downstream of upr troffing over the w that wl be
deepened as some potent shrtwvs over the Pacific dig into the wrn
states. Although a hi pres rdg extending fm Hudson Bay thru the
Great Lks states wl dominate the sfc pattern, h85 temps rising fm
about 0C at 12Z Sun to arnd 4C over the w half by 00Z Mon as well as
a good deal of sunshine wl support well above normal temps,
including max temps on Sun that reach at least near 50 away fm lk
moderation. But light winds under the sfc rdg axis wl allow for lk
breeze dvlpmnt and sgnft cooling closer to the shores that hold hi
temps in the 30s. There could be some fog on Sun ngt over mainly the
e half with lgt winds under the slowly passing rdg axis that wl
support lower min temps in the 20s. Strengthening sly flow over the
w that holds up the min temps there wl limit the potential for fog

Mon into Tue...Shrtwv energy lifting out of the wrn trof wl support
a sfc lo pres moving fm the nrn Plains toward Hudson Bay. After some
sunshine on Mon mrng, there wl be thickening clds under the incrsg
deep sly flow/waa btwn the retreating sfc hi pres and the lo passing
to the w. Since the lo pres wl be moving to the w of Upr MI, pcpn
that falls under the associated slowly passing warm conveyor belt
mstr ribbon wl fall as rain as h85 temps are fcst to rise up to
8C. Pwats rising aos an inch and slow moving warm conveyor belt
could result in some locally heavy ra. Depending on how quickly
winds diminish late Mon night into Tue, there could also be some
at least locally dense fog later Mon ngt into Tue over mainly the w
after the warm conveyor belt shifts to the e, allowing for mid lvl
drying after the steadier ra diminishes over the melting sn pack.
Arrival of vigorous mid lvl drying/sfc hi pres on Tue wl cause the
ra to diminish w-e. The return of more sunshine in the presence of
h85 temps arnd 5C should allow max temps to rise aoa 50 away fm lk

Tue ngt-Wed ngt...Another shrtwv emerging fm the mean wrn trof is
fcst to ride ewd thru the Upr Lks. Although mstr inflow wl be
limited, fcst 12hr h5 hgt falls aoa 100m on cyc side of supporting
h3 upr jet axis and rather sharp cyc flow along attendant cold fnt
that passes on Wed wl support at least a chc of some showers. Since
h85 temps are fcst to fall no lower than -2C to -5C on Wed ngt
behind the fropa, there wl be no lk effect pcpn.

Thu/Fri...Another potent, incrsgly negatively tilted shrtwv and deep
sfc lo pres are fcst to lift newd fm the Plains toward the Upr Lks.
Although there have been some sgnft model differences on the fcst
track and intensity of this disturbance/lo pres, the 12Z guidance,
with the support of the 00Z GFS ensemble mean, has come into better
agreement showing a trend toward a deeper sfc lo tracking farther to
the nw. Raised fcst temps a bit to reflect this trend. But there
remain some timing differences, with the faster 12Z GFS showing pcpn
arriving as soon as Thu aftn as compared to the 12Z Cndn model that
indicates pcpn wl hold off until Fri aftn. The trend toward a
deeper, farther nw track would support more mixed pcpn changing to
mainly ra. Wl retain extended model consensus fcst for now.

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1227 AM EST SAT FEB 18 2017

Expect mostly prevailing VFR conditions through Sat. There is a
slight chance of MVFR cigs developing at KIWD and KCMX late tonight
into Sat morning as winds shift westerly to onshore/upslope
direction in the wake of a cold frontal passage. However, confidence
in lower cloud deck forming was too low to include in the fcst at
this time. Did include a tempo group from 06-08z overnight for MVFR
fog at KSAW. Expect LLWS at most sites tonight into early Sat.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 332 AM EST SAT FEB 18 2017

No gales or heavy freezing spray is expected in the forecast period.

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


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