Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 132347

Area Forecast Discussion
National Weather Service Marquette MI
647 PM EST Tue Feb 13 2018

.SHORT TERM...(This evening through Wednesday)
Issued at 1247 PM EST TUE FEB 13 2018

Mid-level clouds continued to stream across much of the area this
afternoon as warm air advection ahead of a subtle shortwave
increased across the region. Gusty winds increase through the late
morning and early afternoon hours as pressure falls began to
overspread the region. Through the morning and early afternoon
hours, radar returns have showed up across the area; however, little
if any snow has reached the ground due to the sharply dry low-level
air in place.

No precipitation concerns over the next 24 hours, but we will see
breezy and warming conditions. Tonight, a synoptically enhanced 45
to 50 knot low-level jet is progged to track across the area. Given
the increasing warm air advection associated with this low-level
jet, lapse rates through the low-levels will not support
persistently strong and gusty winds, but it`s not out of the
question that we will see occasional wind gusts upwards of 25 to
30mph at times tonight, especially across the higher terrain, over
the Keweenaw Peninsula, and near the shoreline of Lake Superior
around and east of Marquette. This warm air advection coupled with a
turbulent boundary layer should limit the degree of diurnal cooling,
keeping overnight lows fairly mild compared recently.

A clipper system will track towards the Arrowhead of Minnesota,
drawing in even warmer air for Wednesday. With 850mb temperatures
approaching 2-4C by the afternoon hours, this should easily support
temperatures climbing above freezing, even pushing into the lower
40s where sunshine and/or downsloping flow develop due to southwest

.LONG TERM...(Wednesday night through Tuesday)
Issued at 333 PM EST TUE FEB 13 2018

Summing it up we will see varying temperatures through the extended
time range. After a prolonged period of quiet weather could see some
chances of at least light system snow this weekend into early next

After the brief warm up this week, much colder air returns later
Thursday into Saturday as upper level troughing drops across Upper
Great Lakes region. Initially moisture is shallow and temps in moist
layer are warmer than -8c, so as long as there is enough saturation
blo cloud base, drizzle would be prime precip expected. Eventally by
late Thursday, enough cold air works in 2-3kft AGL to lead to only
snow as ptype, but that may take until Thursday night over the
eastern forecast area. If there is drizzle, could see issues with
light icing as sfc temps will be falling from middle 20s to the
teens Thursday afternoon. Upslope flow/lift will be most pronounced
over west and northwest forecast area so that could be where main
issues would occur. Colder air arrives in full force Thursday night
into Friday as H85 temps drop to -22c to -24c. Though plenty cold
for lake effect, expansive ice on Lk Superior and overall dry
airmass with anticyclonic flow dominating will put crimp in lake
effect Thursday night and especially on Friday as sfc ridge builds
into western Great Lakes.

Core of coldest air slides off Friday Night and Saturday but another
shot of colder air pushes back across Saturday night into Sunday.
Brief period of warm air advection may lead to light snow in some
areas on Saturday (mainly less than 1 inch). If recent runs of GFS
are correct, better setup for some light or moderate snow would
occur late Sunday into Sunday night. ECMWF keeps main focus for snow
north of Upper Michigan while latest GEM is more in line with GFS.
Though operational GFS would support a lower end advisory especially
northern forecast area, even the highest snowfall projections from
GFS ensemble system (GEFS) would indicate snowfall from this event
stays below advisory levels.

Strong jet on front side of trough exits off east coast on Sunday
with upstream jet digging over western conus leading to troughing
developing over western half of the Conus early next week. Expect
warmer and more active weather pattern into next week. Degree of
warmth not apparent yet. GEM is quite aggressive with warming next
week but does not come even close to matching GEM ensemble mean.
Could see additional widespread snow early in the week but not sure
how far northwest the system causing that snow will track. Probably
turns colder later in the week as long as the much warmer operational
GEM idea is not on the right track.

.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 647 PM EST TUE FEB 13 2018

VFR conditions should prevail at KIWD/KCMX/KSAW thru this fcst
period. There is some concern that melting snow that occurred today
well upstream and the moisture added to the low levels could yield
some low clouds later tonight. For now, that potential appears very
low. Otherwise, low-level wind shear is expected tonight as the axis
of a low-level jet translates across the area. The stronger winds
aloft will also reflect down toward the surface and allow for
intermittent gusty winds at all terminals.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 1247 PM EST TUE FEB 13 2018

Southwest gales to 35 knots are expected this afternoon through
tonight across central and eastern Lake Superior, diminishing before
sunrise Wednesday. These will be the strongest winds for this
forecast period, with gusts up to 30 knots expected through
Wednesday, and again on Saturday.

Upper Michigan...
Lake Superior...
  Gale Warning until 1 AM EST Wednesday for LSZ266-267.

  Gale Warning until 10 PM EST this evening for LSZ265.

  Gale Warning until 7 AM EST Wednesday for LSZ263-264.

Lake Michigan...


SHORT TERM...Ritzman
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