Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 220734
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
234 AM EST Wed Nov 22 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 407 PM EST TUE NOV 21 2017

WV imagery and RAP analysis indicated an amplified pattern with a
mid/upper level trough from Hudson Bay through the western Great
Lakes into the mid MS valley. 700-300mb Qvector div and subsidence
developed over Upper Michigan in the wake of a shrotwave trough to
the east of Lake Superior. However, another weaker shrtwv was
sliding into nrn Ontario (north of KINL). At the surface, gusty nw
winds prevailed over the region bewteen a 990 mb low se of James Bay
and 1033mb high pres building into the nrn plains. Radar indicated
that multiple wind parallel LES bands have gradually diminished this
afternoon as inversion heights drop to 4k-5k ft.

Tonight, 850 mb temps around -14C will provide enough instability
for continued LES even as 850-700 mb moisture moves out this
evening. The shrtwv moving through may provide a brief boost to the
LES. Winds backing to wnw overnight will shift the best chance for
additional accumulations from Munising eastward. Expect additional
accumulations of 1 to 3 inches in the favored nw flow locations.
Otherwise, only a few flurries or light dusting will be possible.

Wednesday, backing winds push the remaining LES bands in the east
offshore by afternoon. Mid/high clouds will increase in the aftrnoon
ahead of the next clipper shrtwv. Even with WAA, temps will only
climb into the mid to upper 20s.

.LONG TERM...(Thursday through Tuesday)
Issued at 234 AM EST WED NOV 22 2017

Nam shows a 500 mb ridge across the western U.S. and troughing
across the east half of the U.S. 12z Thu. A trough moves from
western Canada to the upper Great Lakes Fri night. Nam shows some
moisture and 850-500 mb q-vector convergence 12z Fri into Fri night
moving through the area. Overall, did not make too many changes to
the going forecast. Did remove any freezing pcpn for Thanksgiving as
it looked to cold for freezing rain. Looked like a snow/rain
possibility for that day in the ern cwa.

In the extended, GFS and ECMWF show a 500 mb ridge in the western
U.S. and a deep and broad 500 mb trough across the ern half of the
U.S. 12z Sat. 850 mb temperatures 12z Sat across Lake Superior are
from -9C to -13C and with lake temperatures around 4C, that is
enough for lake effect snow. The ridge amplifies on Sun across the
western U.S. with troughing in New England. The ridge moves into the
plains 12z Mon as troughing moves onto the west coast. The trough
moves into the Rockies 12z Tue and into the plains by 00z Wed and
into the upper Great Lakes on Wed. Temperatures look to be above
normal for this forecast period.
&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1150 PM EST TUE NOV 21 2017

MVFR conditions and lake effect -shsn/flurries will continue at
KIWD/KCMX until winds back to the sw when high pres ridge passes
this morning/early aftn. VFR conditions will then continue into the
evening hrs. At KSAW, downslope nature of the nw flow should allow
cigs to vary from high MVFR to VFR overnight with -shsn/flurries
ending. VFR conditions will then prevail at KSAW today into this
evening.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 407 PM EST TUE NOV 21 2017

NW gales across much of Lake Superior will end by late evening.
Winds will diminish to under 25 knots while becoming westerly
through Wednesday morning, before backing to SW winds of 20 to 30
knots Wednesday night. Westerly winds of 20 to 30 knots Thursday
will back to the south on Friday. Another strong low pressure system
will then bring the potential for northwest gales of 35 to 40 knots
Friday night into Saturday.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...JLB
LONG TERM...07
AVIATION...Rolfson
MARINE...JLB



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