Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 212041 CCA
AFDMQT

Area Forecast Discussion...CORRECTED
National Weather Service Marquette MI
341 PM EST Tue Feb 21 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 250 PM EST TUE FEB 21 2017

Skies have cleared nicely this afternoon and has allowed to
temperatures to climb into the upper 40s and 50s, with a few
isolated 60s. Water vapor imagery shows shortwave energy lifting
northeast of the area and allowing more zonal flow to develop
across the northern plains.

Expect fairly tranquil conditions to prevail tonight and through
much of the day on Wednesday. With dew point temperatures expected
to remain around/slightly above freezing tonight, we should see yet
another night where overnight lows remain above freezing. There is
the potential to see fog, especially across eastern portions of the
area where boundary layer winds will be lighter. Could see some
drizzle develop; however, with how dry the low-levels look via
soundings not too confident that any drizzle will accompany the
fog.

On Wednesday, expect another day with unseasonably warm
temperatures, but expect increasing cloud cover throughout the
day as low pressure begins to move in from the west as shortwave
energy approaches the area. Precipitation should hold off until
the late afternoon/evening hours as it spreads west to east upon
the arrival of the deeper lift. Forecast soundings show
temperatures should remain above freezing, so expect precipitation
to remain all liquid at least through the afternoon and evening
hours, before transitioning back over to wintry precipitation late
Wednesday night.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 312 PM EST TUE FEB 21 2017

Models have backed off some on strength of shortwave/system moving
through the Upper Great Lakes late Wed/Wed night. Still plenty of
model uncertainty with track and details regarding system, but at
this time it looks like a light mixed pcpn event focused mainly over
the northern tier counties of Upper Mi.

After a dry and cooler Thu, attention then turns to Fri into Sat as
models continue to bring a strong low pressure system toward the
Upper Great Lakes. Although there continues to be uncertainty on the
track/timing of the sfc low, most of the models have trended farther
north in the past run with a track closer to northern Lower
Mi/Straits of Mackinac. Would expect poor model continuity and
consistency to continue until the shortwave associated with the
system moves onshore late Wed. Given the current track of the GFS,
NAM, ECMWF and GEMnh, the nw half of the CWA would see mostly snow,
with moderate to possible heavy snow over the higher terrain of west
and north-central U.P. where upslope and lake enhancement will add
to synoptic amounts. The southeast half of Upper Mi would see more
mixed pcpn. Both the GFS and NAM show the system`s dry slot moving
across the area on Fri into Fri evening which in this scenario would
lead to freezing drizzle/light freezing rain accumulation for
portions of central Upper Mi...especially those locations favored by
an upslope nne flow. Blowing snow could also be an issue during the
event, especially near Lake Superior where forecast soundings show
the potential for wind gusts at or above 30 mph. At any rate, with
plenty of uncertainty will need to keep an eye on model trends with
this system over the next few days. No SPS statement will be
issued as yet, but will continue to mention in HWO statement moderate
to possibly heavy snow accumulation for portions of west and central
Upper Mi late Thu night into Sat.

Sat-Sun...Snow will transition to pure lake effect sometime Sat
afternoon as falling H85 temps in the wake of the departing system
will sustain LES in the NW-W wind snow belts downwind of Lake
Superior and bring temps back down closer to seasonal norms.

Models indicate ridging building over the area on Mon which should
bring an end to LES as well as some slight moderation in temps.
&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 106 PM EST TUE FEB 21 2017

Skies will remain mostly clear through this afternoon, with a few
lingering scatter low-level clouds across the Keweenaw and
lightening winds as weak surface ridging moves overhead. Tonight
into Wednesday morning as a surface low will begin to track across
the area, winds look fairly light and even variable at a few
terminals, especially KCMX/KSAW. Models are fairly consistent with
stratus filling in across all terminals early Wednesday morning.
Not terribly confident in how low visibilities will get, with
boundary layer winds between 10-15 knots, so have opted to go with
high-end IFR ceilings and MVFR visibilities for now.
&&

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 300 PM EST TUE FEB 21 2017

Winds will back to the south overnight ahead of a weak area of low
pressure progged to traverse the northern plains tonight. The
pressure gradient will remain maximized, albeit still on the weaker
side across eastern portions of the lake where winds of 15 to 25
knots can be expected. Late Wednesday as low pressure traverses the
area, winds will veer to the north from west to east across the
lake, around 10 to 20 knots. As low pressure exits the region
Wednesday night into Thursday expect north winds to increase in
speeds to around 25 knots. Winds will decrease in speed during the
day on Thursday as the pressure gradient relaxes. However, expect
winds to become northeasterly and increase in speed Thursday night
into Friday ahead of a system progged to lift north across the area.
By Friday morning, northeast winds will increase to around 25 to 30
knots, and further increase to gales during the afternoon hours.
Friday night into Saturday, could still see the gale force gusts
continue, but winds will back to the north.
&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&

$$

SHORT TERM...Ritzman
LONG TERM...Voss
AVIATION...Ritzman
MARINE...Ritzman



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