Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 190659

Area Forecast Discussion
National Weather Service Marquette MI
259 AM EDT Thu Oct 19 2017

.SHORT TERM...(This evening through Thursday)
Issued at 345 PM EDT WED OCT 18 2017

...Windy into this evening then again on Thu...

Surface low over northern Manitoba down to 973mb at 19z/4-5 standard
deviations below mid October mean is resulting in warm and windy day
across much of Upper Michigan. Temps over portions of western U.P.
have reached over 20F above normal in the middle 70s. Warm spot as
of 3 pm in Upper Michigan is on the Keweenaw near the Upper Entrance
of the Portage Canal. Houghton Co Airport not far behind at 75F.
Pretty warm for mid to late October. Should note the record high for
today in the Houghton area is 80F set in 1910.

Dry airmass ahead of the low and associated cold front is leading to
just a batch of mid clouds over northern Ontario into western Upper
Michigan. Cold front crosses region late tonight with winds shifting
from southwest to west. Based on RAP soundings showing mixed layer
winds over 35 kts/40 mph, current obs and pressure falls crossing
north of Lk Superior into early this evening, expect wind gusts over
40 mph from north central into eastern forecast area. Issued special
weather statement into early evening to cover the strong winds.

West winds ramp back up on Thursday behind the cold front. Strongest
wind gusts 30-40 mph will be across Lk Superior and Keweenaw
Peninsula but 15-30 mph gusts could also occur over rest of forecast
area. Even with cooler airmass compared to today, temps on Thursday
will top out in the low to mid 60s, which is still well above
normal. Min RH values will bottom out in the 20-25 percent range so
fire weather concerns may be elevated especially given the recent
stretch of warm/dry weather.

.LONG TERM...(Friday through Wednesday)
Issued at 259 AM EDT THU OCT 19 2017

Troughing in the west and a ridge over the ern U.S. will be found
12z Fri. The ridge moves to the eastern seaboard 12z Sun while the
trough moves into the plains. Dry weather looks to hold into Sat
before chance pops move into the west late and then they gradually
move to the east. Did not make too many changes to the going
forecast. Above normal temperatures continue this period.

In the extended, GFS and ECMWF show a 500 mb trough over the central
U.S. Sun with a sfc cold front moving through the area. More
troughing remains over the area for Mon and then cold air with a
digging trough comes in for Tue. This 500 mb trough digs further for
Wed with 850 mb temperatures dropping to -5C to -6C. With Lake
Superior being around 10C to 12C, this would be enough for lake
effect pcpn. The trough moves into the ern U.S. on Thu. Above normal
temperatures continue into Mon and then cooler and near normal
temperatures come in for Tue and beyond.

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 105 AM EDT THU OCT 19 2017

VFR conditions are expected to prevail over the next 24 hours. A
cold front will push east across all terminals tonight veering winds
to the west. Breezy winds will likely persist behind the front. LLWS
is also expected to develop after surface cooling and decoupling
Thursday evening with a developing inversion.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 345 PM EDT WED OCT 18 2017

South to southwest winds to 30 kts with a few gale gusts to 35 kts
over eastern sections will continue into the evening. Cold front
crossing tonight will shift winds to west and these may gust to 30
kts late tonight into early Thu aftn and once again there may be
gale gusts to 35 kts over east half. Overall, expect winds to stay
25 kts or less Thu night into early next week. Winds could increase
to 30 kts late Fri night into Sat though as pressure gradient
briefly tightens up ahead of low pressure tracking across south
central Canada.

Upper Michigan...
Lake Superior...
  Gale Warning until 5 PM EDT this afternoon for LSZ266-267.

  Gale Warning until 5 PM EDT this afternoon for LSZ243>245-264.

  Gale Warning until 2 PM EDT this afternoon for LSZ263.

Lake Michigan...


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