Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 190506

Area Forecast Discussion
National Weather Service Marquette MI
106 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...(Thursday night through Wednesday)
Issued at 404 PM EDT WED OCT 18 2017

Thursday night through Friday night: Fairly quiet weather is
expected through this time period as high pressure will remain in
control. Aloft, upper level ridging in place will keep temperatures
above normal through this time period, in fact, many places will be
around 15 to 20 degrees above normal through this time period. For
perspective, average temperatures this time of year area right
around the low 50s.

Saturday into Sunday: An upper level trough is expected to slide
from the Plains eastward through the Upper Great Lakes region
through this time period. At the surface, the associated strong
surface low is expected to slide north of the area, and remain
mainly over Canada. This will drag a cold front through the Upper
Peninsula Saturday afternoon and night and then to the east of the
area by Sunday evening. Increased moisture and forcing and
moisture ahead of the front will allow for widespread rain showers
to spread across the U.P. Current model trends have roughly a
half inch of precip across the area by the time the precipitation
ends Sunday afternoon. There may be just enough instability around
for Saturday afternoon and Saturday evening ahead of the front
for a few thunderstorms; however, thunderstorm potential does look
to be fairly marginal overall. Temperatures will be about 10 to
15 degrees above normal through this time period.

The rest of the extended: There will likely be a brief break in the
precipitation Sunday night as a brief ridge builds into the area;
however, another slow moving low pressure system is expected to
slide through for Monday through Wednesday. Aloft, a much deeper
trough will dig into the Upper Great Lakes region. This will allow
enough cold air to slide into the region to cause some snow to mix
in with the rain over the higher terrain of the west. The ground is
still warm and overall QPF is not expected to be that impressive, so
not expecting too much in the way of accumulation. 850mb
temperatures are progged to drop into the -5C to -7C range, creating
delta-T values in the 17 to 19C range. This will be prime for lake
enhancement. The favored areas will have to be pinned down as models
come into better agreement, but it looks like the northwest wind
lake effect prone areas would have the best chance at this point.
Model consensus was used and appeared to work well for this time

.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...
Lake Michigan...


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