663
FXUS63 KMQT 250921
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
421 AM EST Mon Nov 25 2024

.KEY MESSAGES...

- Occasional snow today, mixed with rain near the Great Lakes.
  Higher snowfall rates and better accumulating snow occurs this
  afternoon into the evening, mainly over the east half of Upper
  Michigan. Snow accumulations of 3 to 6 inches expected for
  much of the interior U.P. through this evening, with lower
  totals along the Great Lakes shorelines.

- A Winter Weather Advisory has been issued for most of the U.P.
  through to this evening. Slippery travel conditions are
  possible for the morning and evening commutes today.

- Lake-effect snowfall continues for snow belts favored by west-
  northwest to northwest winds for the rest of this week
  through this weekend. Expect several inches of fluffy snowfall
  to fall over these snow belts over the next 7 days.

- Temperatures will become below normal for this time of year by
  late this week, with high temperatures failing to reach
  freezing by then.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 420 AM EST Mon Nov 25 2024

Water vapor imagery and RAP analysis show a mid-level low centered
on the southern portion of the Manitoba/Saskatchewan border. To the
s, a shortwave moving across the central Plains is the main feature
of interest for the short term. At the sfc, reflection of the wave
is low pres over western IL. Initial push of waa in response to the
wave has resulted in -sn lifting into Upper MI during the night. It
appears any mix with rain has been confined close to the Bay in
Menominee County. Webcams show that snow is accumulating on roads,
leading to slippery travel conditions. Snow has yet to arrive in the
eastern fcst area. Current temps are mostly in the upper 20s to
lower 30s F.

There has been a clear trend in recent model guidance for the initial
snow today to be lighter. In fact, there is likely to be a period
this morning, perhaps several hours, with little in the way of
snowfall for many areas. Then, the main push of accumulating snow
occurs this aftn into early evening as shortwave begins a trend
toward taking on a negative tilt. Deep layer q-vectors show a nice
increase in convergence, maximizing over roughly the e half of Upper
MI late today, and that is where guidance now paints highest qpf.
Given agreement on trends, this fcst issuance will follow suit.
Ptype along the Great Lakes is likely to remain a mix of rain/snow
or to become a mix of rain/snow for much of those areas. By 00z this
evening, expect a general 2-4 inches of snow accumulation.
Accumulations will trend down to less than 1 inch along the Great
Lakes. Expect high temps in the lower to middle 30s F.

&&

.LONG TERM /TONIGHT THROUGH SUNDAY/...
Issued at 343 AM EST Mon Nov 25 2024

Expect the transition from system to lake-effect snowfall over the
northwest snow belts tonight as the system responsible for the
snowfall today continues lifting northeastward towards the St.
Lawrence Seaway. While warm temperatures near the Lake Superior
shoreline will severely limit snowfall accumulations tonight into
Tuesday close to it (expect around a trace, if that), expect to see
an increasingly dry/fluffy 1 to 4 inches of snowfall over the
northwest snow belts tonight, with up to an inch still being seen
outside of the northwest snow belts in the interior too. That being
said, with winds increasing from the northwest up to around 35 mph
along the Lake Superior shoreline tonight through Tuesday, we could
see windy conditions by Lake Superior and the Keweenaw during this
time period as modest cold air advection works into our neck-of-the-
woods. As pre-conditioning from Lake Nipigon begins to increase the
moisture flux of the lower atmosphere over eastern Lake Superior
Tuesday, we could see heavy snowfall rates appear at times, with the
00z HRRR showing composite reflectivities over 40 dBZ in some of the
snow bands (up to 2+ inches/per hour snowfall rates)! While we plan
to extend the Winter Weather Advisories for the western U.P. for the
lake-effect snow through tonight (and possibly into Tuesday too), we
could see locally higher snow totals over the east Tuesday and
Tuesday night as Lake Nipigon-influenced bands could make their way
across this portion of our CWA; we may need to consider restarting
or continuing Winter weather headlines over there in the future.

Lake-effect snow looks to continue over mainly the west-northwest to
northwest snow belts over the next several days as general troughing
remains over eastern Canada/New England. That being said, expect to
see a weakening to the lake-effect snowfall Wednesday into possibly
Thanksgiving Day as very weak shortwave ridging skirts through the
Upper Midwest. Once we get into late this week (late
Thursday/Friday), another shortwave low drops down from the Canadian
Prairies and reinvigorates the lake-effect snowfall over the west-
northwest to northwest snow belts. Expect several additional inches
of dry and fluffy lake-effect snow to accumulate over these snow
belts through the rest of this week through this weekend, with pre-
conditioning from Lake Nipigon still enhancing totals over the
eastern half. Another shortwave low dropping down from Canada looks
to keep the strong lake-effect snow going through this weekend into
early next week. Expect temperatures to feel a little chilly, even
in comparison to this time of year climatologically speaking, as
highs are looking to remain below freezing across most of the U.P.
from Thursday onwards.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1215 AM EST Mon Nov 25 2024

MVFR conditions prevail to start the TAF period, but expect them to
deteriorate to IFR and LIFR as snowfall fills in through the early
to mid-morning hours (80% confidence in IFR or lower conditions
today). Timing for IFR conditions appears to be around 10Z for IWD
and 13Z for SAW/IWD, with lowest vsby in snowfall of less than 1 nm
from about 15-22Z (50% probability of vsby less than 1 nm). IFR cigs
likely stick around into this evening even as steady snowfall
departs. Lake effect snow showers may continue to reduce vsby at
times into the evening.

&&

.MARINE...
Issued at 343 AM EST Mon Nov 25 2024

Light winds of generally 20 knots or less continue over the lake
today until a cold front associated with a shortwave low dropping
from the Canadian Prairies brings northwest winds of 20 to 30 knots
across the lake this evening through Tuesday from west to east;
expect a few gale force gusts up to 35 knots from time-to-time near
the southern shoreline. As weak ridging skirts its way across the
Upper Midwest through the mid-week, expect the winds to lighten to
less than 25 knots late Tuesday night, remaining that way until late
this week (most likely Friday). As a shortwave low from Canada drops
back across the western Great Lakes late this week, expect the winds
to increase from the northwest to 20 to 30 knots across the lake.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Winter Weather Advisory until 7 PM EST /6 PM CST/ this evening
     for MIZ001>005-009>011-084.

  Winter Weather Advisory until 1 AM EST Tuesday for MIZ006-007-
     013-014-085.

Lake Superior...
None.
Lake Michigan...
None.

&&

$$

SHORT TERM...Rolfson
LONG TERM...TAP
AVIATION...Thompson
MARINE...TAP