Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 150804

Area Forecast Discussion
National Weather Service Marquette MI
404 AM EDT Thu Mar 15 2018

.SHORT TERM...(Today and tonight)
Issued at 402 AM EDT THU MAR 15 2018

No major weather impacts expected during the short-term portion of
the forecast.  Light lake effect snow for northwest wind snow belts
will be the only minor issue early in the day.

Today: Upper level troughing over the eastern half of the U.P. this
morning, will give way to steady height rises throughout the day.
Early in the day, a couple quick moving shortwaves will brush the
eastern U.P., allowing for light lake effect snow showers under
ideal temperature differentials between the surface and 850mb.
Again, due to limited overall moisture sliding through, only light
snowfall accumulations are expected through the morning hours.
During the afternoon a dry high pressure system is expected to build
into the western U.P. The anticyclonic flow along with even drier
flow into the area will lead to a steady decrease in lake effect
snow over the west half along with a decrease in cloud cover. The
eastern U.P. will likely see some lingering snow showers into the
afternoon, along with continued low to mid cloud cover.

Tonight: As the aforementioned surface high becomes more centered
over the U.P., expected winds to steadily decrease and become nearly
calm. The combination of calm winds and little to no cloud cover,
will create ideal conditions for maximum radiational cooling. This
will likely lead to temperatures in the single digits below zero
over the inland west, while the eastern U.P. may stay slightly
warmer as that area will be a bit closer to pressure gradient.
Otherwise, quiet weather conditions can be expected tonight.

.LONG TERM...(Friday through Wednesday)
Issued at 402 AM EDT THU MAR 15 2018

A quiet stretch of late winter/early spring weather is on the way
thru next week. Currently, an amplified ridge extending from the
western Plains n thru the Northwest Territories is supporting a deep
trof over the eastern CONUS. Over the next few days, the upstream
ridge will fade away, and split flow will become more pronounced
across N America thru the middle of next week. With the northern
stream featuring a trof over eastern Canada, shortwaves and
associated pcpn tracking across the CONUS in the southern stream
will likely be forced s of Upper MI by the eastern Canada trof.
During the last half of next week, ridging will build across the
Plains then shift to the Great Lakes in response to a trof
developing into the western CONUS. These large scale changes will
support a dry period of weather for Upper MI. It`s quite possible
that many locations will not see any pcpn for the next 7 days, and
the dry weather may even extend thru the end of next week, depending
on how progressive the late week pattern is across the CONUS. There
will be some LES off Lake Superior today which will diminish/end
from w to e this aftn/tonight. The only other potential of any pcpn
over the next 7 days, and that looks doubtful, will be early next
week as a shortwave dropping into the eastern Canada trof pushes
colder air into the Upper Lakes, possibly cold enough to support a
little light LES off Lake Superior. As for temps, readings on most
days won`t stray far from normal, but max departures from normal
will be as much as around 10 degrees over the next few days. The
coldest day will be today and the warmest day Sat.

Beginning Fri/Sat...With sfc high pres dominating Fri, expect a
sunny day though there may be some stratocu over the e in the
morning before 850mb temps moderate further. Expect high temps in
the 30s, but some locations over the interior w may reach 40F. A
very weak sfc trof will slip s across the area Fri night with
essentially no impact on the weather. Under mostly clear skies/light
winds, favored the global CMC bias corrected for mins since it is
typically a superior performer on radiational cooling nights.
Traditional cold spots should see temps bottom out around 5F. Temps
will range up to 15-20F near the Great Lakes. Model RH fields
suggest there be some sct clouds on Sat, particularly across the n
and e. High temps will be higher than Fri, rising well into the 40s
over the interior w half.

Shortwave tracking thru northern Ontario will send a cold front s
across Upper MI late Sat night or Sun morning. Limited
moisture/forcing and 850mb temps too high to support lake
enhancement as the front passes suggest fropa will likely be dry.
Models have waivered on the degree of CAA in the wake of the cold
front, but the last 24-36hrs of models runs have generally suggested
850mb temps only perhaps just reaching the marginal threshold for
LES. Given that the low-level flow will become notably anticylonic
by the time the coldest air arrives, it seems unlikely that any LES
will develop Sun night into Mon. Meanwhile, shortwave tracking
across the CONUS in the southern stream early next week is likely to
pass well s of the area due to the se Canada troffing in the
northern stream. Compared to the last 2 runs, there are considerably
fewer CMC ensembles now in the 00z run that track the wave far
enough n to bring pcpn into the fcst area, and there are only a few
GFS ensembles that do. Medium range models do show an inverted sfc
trof extending from the sfc low back into the Dakotas/western MN in
response to an upstream shortwave diving from the western Dakotas
toward the mid Mississippi Valley. SE track of this energy while sfc
high pres dominates northern Ontario to provide a feed of dry air
suggests this pcpn will not reach Upper MI. As a result, will carry
a dry fcst Mon thru Wed. Building mid-level ridge shifting from the
Plains to the Great Lakes should then maintain dry weather Thu/Fri
as well.

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 140 AM EDT THU MAR 15 2018

Lake effect clouds and snow will continue into Thursday. Models
continue to handle lake effect quite poorly, so there is uncertainty
with visibilities. Don`t think visibilities will drop too far given
light snowfall expected, but that will need fine tuning as
conditions develop. VFR conditions will occur at all sites Thu

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 402 AM EDT THU MAR 15 2018

North to northwest winds of 20 to 30 knots can be expected today,
strongest over the east half of the lake. There could be a few gale
force gusts to 35 knots through this afternoon, but currently not
expecting widespread gales. Otherwise, the rest of the week into the
weekend, winds should remain at or below 20kts on Lake Superior.

Upper Michigan...
Lake Superior...
Lake Michigan...


LONG TERM...Rolfson
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