Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 241149

Area Forecast Discussion
National Weather Service Marquette MI
649 AM EST Wed Jan 24 2018

.SHORT TERM...(Today and tonight)
Issued at 427 AM EST WED JAN 24 2018

Fairly quiet weather expected in the short term as light lake effect
snow/flurries essentially end later this morning.

Today and tonight, winds already turning ne on Lake Superior will
continue to veer east through the late morning hours and then
southeast in the afternoon as high pressure over nw Ontario slides
se. This will eventually push any remaining light lake effect
snow/flurries (now prominently over north central Upper Mi)
across the Keweenaw Peninsula. IR satellite imagery show mid-level
clouds moving into west and central Upper Mi early this morning
in advance of an approaching shortwave trough moving through
southern Manitoba and northern MN. Models indicate this moisture
will stick around through the morning hours resulting in mostly
cloudy skies, but then drying and subsidence behind the shortwave
could result in breaks to cloud cover later this afternoon into

Expect max temps today to range from the upper teens east to the mid
20s west and south central. Min temps tonight will generally range
from the single digits above zero over the interior to the low teens
for sw flow downsloping locations along Lake Superior.

.LONG TERM...(Thursday through Tuesday)
Issued at 424 AM EST WED JAN 24 2018

With a progressive pattern the rule for the next week or so, temps
thru the end of the month will be variable in response to a
progression of ridges and trofs across the CONUS, but with a
tendency for more above normal than blo normal days. This would be
consistent with the signal from the current active MJO which is now
moving into phase 5, over the Maritime Continent, which favors
warmth/ridging over the eastern CONUS. Farther down the line,
guidance suggests the MJO will remain very active, and as it shifts
to the Western Pacific and toward the western hemisphere, it should
be mechanism to force a return to more persistent cold weather
heading into mid Feb and carrying thru the end of the month. That
said, medium range guidance has recently been indicating a building
ridge near/just off the w coast of N America by the 1st of Feb,
while a separate strong positive height anomaly builds to the nw of
AK. This will set the stage for a deepening central N America trof
and a build up of arctic air over at least much of w and central
Canada in early Feb. This suggests a switch to a more persistent
cold pattern for the Upper Lakes may be in the offing already in
early Feb with the MJO then supporting a continued cold pattern thru
the end of the month. So, it looks like we may end up with a cold
Feb with bouts of bitterly cold air. However, latest CFSv2 ensemble
mean says no to that idea as it depicts a warm mid month period. As
for pcpn, it appears the progressive pattern should only lead to
light pcpn over the next 7 days as energy tends to be focused more
in the northern parts of the passing trofs, supporting sfc low
pressures passing over or n of Upper MI which suggests the more
significant pcpn will pass by to the n.

Beginning Thu/Thu night...WAA regime will strengthen during this
time in response to a trof moving off the ne Pacific and into the
western CONUS. Since low to mid levels are quite dry during the WAA,
there won`t be any pcpn across the fcst area, only an increase in
high clouds.

Warmth will peak on Fri as approaching mid-level trof supports
organizing sfc low pres moving from ND/southern Manitoba into
northern Ontario. High temps will rise into the upper 30s to mid 40s
on gusty s winds. With low pres tracking e to the n of Upper MI Fri
night, it still appears that there probably won`t be any pcpn with
associated cold fropa as gulf moisture/deeper moisture does not meet
up with the front until it passes the area. Fropa will occur Fri
night, but some locations may still stay above freezing under
intially weak CAA. In the wake of the front, should see a fairly
blustery day on Sat under relatively tight pres gradient with 850mb
winds of 30-40kt in CAA regime. With westerly wind direction,
Keweenaw will be favored for strongest winds, probably gusting to
around 40mph. CAA will steadily lower 850mb temps, settling to -15
to -18C for Sun. As a result, LES will develop with time, beginning
for w wind favored snow belts later Sat then shifting to n wind
favored snow belts for Sun as winds veer. LES will be on the light
side, but there are indications of a shortwave passing across the
area at some point Sun or Sun night, and that would give a boost to
ongoing LES.

LES will continue into Mon, but will diminish as flow becomes
anticyclonic with sfc high pres ridge arriving. Strong
WAA/isentropic ascent regime will then quickly develop on Tue ahead
of the next mid-level trof shifting across the western CONUS, and
this should generate a band of -sn that will spread across the area
on Tue. Cold front will then move across Upper MI on Wed with much
colder air and LES following for the late week period.

.AVIATION...(For the 12Z TAFS through 12Z Thursday morning)
Issued at 634 AM EST WED JAN 24 2018

MVFR conditions at KCMX and KSAW in lake clouds should lift to
high end MVFR or VFR this afternoon. VFR conditions at KIWD will
give way to an MVFR cloud deck late morning/early afternoon. VFR
conditions at KCMX and KSAW could lower to MVFR cigs late tonight
as low-level moisture increases in a southerly flow.

.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 427 AM EST WED JAN 24 2018

Winds will remain blo 20 knots through Thursday before increasing to
southeast to south winds to 20 to 30 knots Thursday night into
Friday. South gales to 35 knots are possible over the east half of
Lake Superior Friday morning into early afternoon. Winds will then
shift southwest to west across the entire lake Friday night into
Saturday with gales to 35 knots possible for the west to north
central portions of the lake Fri night into Sat morning. Winds are
then expected to shift northwest Satuday night and northerly on
Sunday while diminishing to 15 to 25 knots.

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


LONG TERM...Rolfson
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