Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 130931

Area Forecast Discussion
National Weather Service Marquette MI
431 AM EST Fri Jan 13 2017

.SHORT TERM...(Today and tonight)
Issued at 431 AM EST FRI JAN 13 2017

Today: Low pressure will continue to slide off through Quebec as
high pressure builds in from the Northern Plains. This morning,
winds ahead of the approaching high and behind the departing low
will be gusty out of the northwest before slowly shifting to the
west and then southwest by mid afternoon. The northwest flow, along
with 850mb temperatures between -16C and -18C, will be sufficient to
keep lake effect snow going for those favored areas this morning;
however the wind shift this afternoon will allow the lake effect
snow to will shift most of the lake effect snow over Lake Superior
and perhaps the tip of the Keweenaw. As the winds shift, the
pressure gradient will continue to relax, allowing winds to steadily
decrease through the afternoon hours. Temperatures will be below
normal with most locations over the western U.P. remaining in the
single digits above zero, while eastern location remain in the low

Tonight: The surface ridge will be directly overhead during the
evening hours before shifting off to the east overnight. The main
impact that this will have on the area will be mainly clear skies in
the evening, which may allow temperatures to drop fairly quick,
before slowly rebounding as the high edges farther to the east and
winds/clouds increase from the south. The southerly winds will help
to keep most of the lake effect snow over Lake Superior, but it is
not out of the question that the tip of the Keweenaw could see some
light lake effect snow. Otherwise, expect it to be a very quiet and
cold night.

.LONG TERM...(Friday night through Thursday)
Issued at 326 PM EST THU JAN 12 2017

A hi pres rdg near the Great Lks wl bring generally dry wx to the
area this weekend. Although the weekend wl start on a seasonably
chilly note, there wl be a warming trend into early next week as upr
hgts begin to rise with the arctic branch retreating n into Canada
and an upr rdg building over the se CONUS. Depending on the track of
a polar branch shrtwv/sfc lo pres lifting ne fm the srn Plains on the
nw flank of the se upr rdg, there wl probably be a mixed pcpn event
arnd Tue. Pacific air and well above normal temps wl dominate much of
next week.

Fri ngt/Sat...A clipper shrtwv embedded in the arctic branch flow is
fcst to track across Ontario to the n of a hi pres rdg stretching fm
the ne states into the Upr MS River Valley. A lo pres trof associated
with the clipper is fcst to cross Lk Sup during this time. But with
an absence of any sgnft mstr inflow and the passage of the sharper
dpva/deep lyr qvector cnvgc to the n closer to the shrtwv track,
expect any accompanying pcpn to be light and limited mainly to areas
near Lk Sup. Some of the guidance does show a weak disturbance
tracking thru WI and bringing some lgt pcpn to the scentral right
under the sfc rdg axis, but if this pcpn does occur it wl be light.
Depending on the cld cover associated with this disturbance, some
locations over the scentral could be quite chilly on Fri ngt with
lighter winds closer to the hi pres rdg axis just to the s. More clds
and a stronger wsw flow over the nrn tier wl limit the diurnal temp
fall in that area. As h85 temps warm to arnd -8C on Sat, expect max
temps to rebound into the 20s.

Sat ngt thru Sun ngt...Hi pres is fcst to build over the Upper Lks
and bring dry wx to the cwa under rising upr hgts as the arctic
branch flow retreats into Canada and an upr rdg builds over the se
CONUS downstream of a trof over the sw states. There wl be a slow
warming trend as h85 temps recover to -2C to -4C on Sun. Lowered fcst
min temps blo the consensus on Sat ngt in areas away fm lk
moderation with light winds and moclr skies.

Mon thru Tue ngt...Concern during this time wl focus on the timing/
pops/ptype associated with shrtwv/sfc lo pres lifting out of the sw
trof toward the Great Lks. Although Mon is likely to be dry until at
least early aftn, some of the faster models indicate some waa sn
well ahead of the sfc lo wl arrive over the scentral in the aftn.
While the longer range guidance continues to show some variability on
the fcst mass/thermal fields with uncertainty on the interaction btwn
the primary shrtwv and another disturbance in the plains, current
trends sug the heaviest pcpn wl fall on Tue and over the central and
ern cwa. Since the bulk of the models show h85 temps rising aoa 0C
over much of the cwa, the associated pcpn is likely to be wintry mix.

Wed/Thu...Expect a drying trend on Wed following the passage of the
disturbance/sfc lo pres to the ne. The zonal flow of Pacific air in
its wake is fcst to lift h85 temps as hi as 5C on Wed, so expect
well above normal temps. This warm, dry wx wl linger on Thu with the
persistent flow of Pacific air.

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1221 AM EST FRI JAN 13 2017

Gusty west winds that have resulted in considerable blsn have
diminished but LES will persist keeping vsby in the IFR/LIFR range.
Winds will gradually diminish overnight with improving vsby as some
light lake effect snow showers continue into Friday morning. The LES
will end by Friday afternoon as high pressure builds into the area.

At IWD, MVFR conditions with light LES will give way to VFR
conditions as winds back to the west.

VFR conditions will prevail at SAW through the forecast period.
However, lake effect clouds may reduce cigs near the MVFR threshold

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 431 AM EST FRI JAN 13 2017

Expect northwest winds to steadily decrease this morning as the
tighter pressure gradient, between low pressure to the east and high
pressure to the west, begins to relax. Heavy freezing spray will be
possible this morning before the winds and waves decrease, so the
heavy freezing spray warning continues into the morning hours. The
pressure gradient will increase once again tonight, between a low
pressure crossing Ontario and the high pressure system moving to the
east of the area tonight, expect southwest winds to increase up to
30 kts and then shift to the west following a low pressure trough
passage on Saturday. There may be a few gale force gusts tonight
into Saturday morning; however, the coverage of these stronger gusts
are expected to be limited. High pressure will then build back into
the area Saturday afternoon into Sunday and possibly even linger
into Monday, allowing winds to diminish under 20-25 kts. An area of
low pressure will approach the Upper Great Lakes Tuesday and move
through Tuesday night; however, the system is not expected to be too
strong, so winds are expected to remain at or below 25 knots through
this time period.

Upper Michigan...
  Wind Chill Advisory until 10 AM CST this morning for MIZ009-010.

Lake Superior...
  Heavy Freezing Spray Warning until 11 AM EST this morning for

  Gale Warning until 6 AM EST early this morning for LSZ245>251-

  Heavy Freezing Spray Warning until 9 AM EST this morning for

  Heavy Freezing Spray Warning until 7 AM EST /6 AM CST/ this
     morning for LSZ240>242-245>247-263.

Lake Michigan...


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