Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 231759

Area Forecast Discussion
National Weather Service Marquette MI
1259 PM EST Thu Nov 23 2017

.SHORT TERM...(Today and tonight)
Issued at 356 AM EST THU NOV 23 2017

No major weather impacts expected through the short-term portion of
the forecast.

Today: A weak shortwave and weak surface trough sliding through
the U.P. this morning will bring some light snow showers or
flurries over the far eastern U.P., mainly east of Munising as
winds become west to west-northwesterly. Otherwise, a surface
ridge over the Mid-Mississippi Valley into the Ohio River Valley
will link up with a weak ridge sliding southeast across Canada.
This will place high pressure across the Upper Great Lakes
throughout the day. This, along with drier air pushing into the
area and warmer air aloft, will bring an end to the precipitation
throughout the day. Cloud cover may linger over the Keweenaw
Peninsula with continued upslope flow off Lake Superior. 850mb
temperatures are progged to steadily warm; however, they should
only warm to around -6C by 00Z/24, again, cool enough for
continued cloud cover, but not cold enough for lake effect
precipitation. Southern and central portions of the U.P. will
likely see the sun sneak out throughout the day, allowing
temperatures to warm into the mid to upper 30s, again, the cooler
areas will be where cloud cover linger through the day, most
notably over the Keweenaw.

Tonight: The surface ridge will shift to the east allowing winds
to become more southerly across the area. At the same time, low
pressure will slide south and eastward into Ontario. This will
allow a weak stationary front to lift north and eastward across
the northern portions of Lake Superior as a warm front. This will
be where the better moisture and forcing/isentropic upglide will
be through the overnight hours. The warmer southerly flow on the
back side of the front and behind the departing surface ridge will
allow temperatures to warm enough, both aloft and at the surface
to keep the precipitation in the form of rain over Lake Superior.
Most of the U.P. is expected to stay dry; however, cloud cover
will steadily increase through the overnight hours. Overnight lows
will be in the upper 20s to low 30s.

.LONG TERM...(Friday through Wednesday)
Issued at 244 AM EST THU NOV 23 2017

Nam shows a shortwave in the northern plains 12z Fri that will move
through the area Fri night. Nam brings in some deeper moisture and
850-500 mb q-vector convergence across the area on Fri and both move
out Fri night. Did not make too many changes to the going forecast

In the extended, GFS and ECMWF show a 500 mb ridge across the
Rockies with a trough off the west coast and another in New England
12z Sun. The ridge moves into the plains 12z Mon. GFS then shows a
trough moving into the upper Great Lakes 12z Tue with cold air while
the ECMWF is slower with the trough by keeping it in the Rockies.
The GFS continues to move things through with a brief cold spell on
Wed while the ECMWF continues to lag behind and waits until Thu to
bring in the colder air. Looks like the manual progs have followed
the GFS solution closely with a brief shot of cold air Tue into Wed.
Temperatures will be at or above normal for this forecast period.

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1259 PM EST THU NOV 23 2017

MVFR cigs at KCMX will give way to VFR conditions by late this
afternoon as winds gradually back to the sw. Otherwise expect expect
VFR conditions throughout the forecast period at KIWD and KSAW. LLWS
is expected to develop late this evening into the overnight hours as
a low-level wind max noses in from the west. Expect gradually
lowering cigs Friday morning as a cold front approaches from the
west. However, conditions should remain VFR.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 356 AM EST THU NOV 23 2017

West to west northwest winds of 15 to 25 knots will back to the
south late tonight into Friday at 20 to 30 knots with gale force
gusts to 35 knots expected. This has led to the issuance of a gale
warning from late tonight into Friday afternoon for most of Lake
Superior. On the back side of the strong low pressure system
additional gales of 35 to 40 knots are possible on colder northwest
flow into the area for Friday night into Saturday. Winds are then
expected to remain in the 20 to 30 knot range through at least mid

Upper Michigan...
Lake Superior...
  Gale Warning from 7 AM Friday to 5 AM EST Saturday for

  Gale Warning from 5 AM EST /4 AM CST/ Friday to 1 AM EST
     /midnight CST/ Saturday for LSZ240>245-263-264.

Lake Michigan...
  Gale Warning from 4 AM to 4 PM EST Friday for LMZ221-248-250.



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