Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 140607

Area Forecast Discussion
National Weather Service Marquette MI
107 AM EST Tue Nov 14 2017

.SHORT TERM...(This evening through Tuesday)
Issued at 243 PM EST MON NOV 13 2017

...Freezing drizzle possible late tonight into Tue morning...

Quiet at this time, though still mostly cloudy, with high pressure
overhead. Had some slippery roads this morning due to light freezing
drizzle off Lk Superior. Could see repeat of that Tue morning,
mainly over western forecast area as drizzle increases in warm/moist
air advection regime btwn the departing high and sfc low sliding
over scntrl Canada. Already seeing signs of increased near sfc
moisture with cigs blo 010 and fog seen over Iowa/northern Illinois
this aftn. This moisture is projected to lift toward northern WI and
western Upper Michigan after 09z on Tue. South winds not that strong
but any additional upslope lifting/moistening would be maximized
over inland west, especially affecting IWD, LNL and IMT. Temps over
inland west half will not rise above 33-34F until later Tue morning
so with any light drizzle there could be icing potential on
untreated roads. QPF from all the models is very light late tonight
into Tue morning so am going to handle fzdz/icing with a SPS.
Evening shift can put out a winter weather advy if more precip looks
to occur.

Later Tue morning into Tue aftn, expect light drizzle to increase to
light rain especially over central U.P. with south winds off Lk
Michigan adding moisture. Overall even though the most widespread
light rain/drizzle will occur during the aftn, the biggest impact
will likely be during the morning due to the temperatures at or just
below freezing.

.LONG TERM...(Tuesday night through Monday)
Issued at 330 PM EST MON NOV 13 2017

A trend toward colder weather and more unsettled weather for the end
of the week into the upcoming weekend. Model solutions still have
significant differences with the weekend system, but it will be
worth keeping an eye on as models come into better agreement.

Tuesday night into Wednesday: The main focus for this time period
will be precipitation associated with a low pressure system sliding
from southern Manitoba eastward into Ontario.  An associated cold
front is progged to shift from the Northern Plains, Tuesday night,
into the far eastern U.P. by Wednesday afternoon. Widespread forcing
and deep moisture along and ahead of the front, will lead to
widespread precipitation across much of the U.P. At this point,
soundings show that the lower levels of the atmosphere are warm
enough that the precipitation should mainly be in the form of light
rain or drizzle at times through early Wednesday afternoon. In fact,
several places may see highs early in the day in the upper 30s to
low 40s. Temperatures will steadily cool through the afternoon hours
as the cold front slips off to the east of the area. As colder air
advects into the area on the back side of the low, expect breezy
conditions to develop through the day with gusts as high as 25 to 35
mph along the Lake Superior shoreline during the afternoon. As
temperatures cool aloft, expect lake effect snow showers to begin
developing by late Wednesday afternoon, probably closer to 00Z/16
before the lake effect really gets going.

Wednesday night through Thursday night: As the low continues off to
the east Wednesday night into Thursday, expect 850mb temperatures to
drop down to around the -10C to 12C range. This, along with north to
northwesterly winds, will allow lake effect snow to develop in the
evening and then continue through much of the overnight hours.
Moisture is not overly deep, just barely into the DGZ, which will
help limit snowfall accumulations. Additionally, inversion heights
are only expected to be around 5kft to perhaps briefly up to 8kft,
which again points to only light lake effect snow. High pressure
will begin building into the area by late Wednesday night through
Thursday, allowing drier air to push into the area. This, along with
winds shifting to the south on the back side of the high, will allow
the lake effect snow showers to end throughout the day.

Thursday night through Saturday: Still some some model differences
on the handling of the lake week into the early weekend system, with
the potential for a stronger storm system moving through the region.
This is largely the result of the phasing of waves moving into the
central U.S. Both the GFS/EC still phase the waves; however, this
happens as the low or just after the low passes off to the east an
northeast of the area and the latest 12Z EC is actually backing off
this idea. In fact, the latest run of the GFS is a little weaker
than the previous run too; however both are still fairly strong. The
EC has a similar idea with the waves phasing just off to the
northeast of the area; however, the 12Z run has actually shifted the
low farther southeast and is much weaker with the system. The
general idea will be WAA advection ahead of the approaching system
with isentropic upglide and increasing moisture allowing widespread
rain showers to overspread the area late Thursday night through much
of the day Friday. In addition, with the increasing pressure
gradient across the area, expect southerly winds to become fairly
gusty Thursday night into Friday. In fact, winds could gust to 25 to
35 mph from the south through this time period. Friday night into
Saturday is the favored time for any phasing to take place to the
east of the area. As this happens, a secondary low is progged to
develop over lower MI; however, there are still some differences in
exact placement of the developing storm system. Much of this, again,
will be directly associated when these waves phase. Either way, it
does still look like a stronger system will develop and likely cause
very strong gusty winds over at least the eastern half of the U.P.
along with some very large waves, possibly leading to some minor
lake shore flooding and beach erosion. Cold air advection on the
back side of the system will allow the rain to transition to lake
effect/lake enhanced snow from west to east throughout the day
Sunday. At this point, west to northwest wind favored snow belts
would be the most likely to see the heavier lake effect snow;
however, with the lack of model agreement on the system details, it
is tough to pin down where the better snow totals may occur.
Additionally, the system is progged to move fairly quickly, so this
may end up pulling the totals back a bit as well. In the end, the
system does have some potential to be a bigger storm; however,
overall confidence in any one solution is not the greatest at this

Rest of the extended: Model solutions continue to diverge for the
rest of the forecast period; therefore will stick with a consensus
of the models. Bringing lower chances of lake effect snow for Sunday
through Monday.

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 104 AM EST TUE NOV 14 2017

Mainly VFR conditions overnight. Conditions will deteriorate Tue
morning to IFR at KIWD and MVFR at KCMX and LIFR at KSAW. Conditions
will stay down at KSAW through the period. Could be some light
drizzle/freezing drizzle Tue morning as well.

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 243 PM EST MON NOV 13 2017

...Gales at times Wed into the weekend...

South winds increase to 20-30 kts Tue/Tue night as pressure gradient
tightens btwn departing high pressure and low pressure tracking over
scntrl Canada. The low crosses Lk Superior and northern Ontartio Wed
morning and expect northwest gales to 35 kts over the east half of
Lk Superior Wed aftn into Wed night. Gale watches have been posted.
Winds diminish Thu but more strong winds are expected Fri-Sun as
strong low pressure system tracks from Upper Great Lakes to eastern
Canada. At the least we`ll see gales with this system and there
could even be storm force winds behind the storm system Sat Night
into Sun morning.

Upper Michigan...
Lake Superior...
  Gale Watch from Wednesday afternoon through Wednesday evening
     for LSZ264>267.

Lake Michigan...


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