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000
FXUS63 KMQT 170528
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
128 AM EDT Wed Apr 17 2024

.KEY MESSAGES...

- A low pressure tracks across the region late on Wednesday,
  resulting in two rounds of rain showers 1) tonight and 2)
  Wednesday afternoon with a 6-12 hour break in between (longest
  west).
- East winds gusting to advisory criteria (45 mph) expected across
  the Keweenaw and eastern U.P. late tonight into Wednesday.
- Temperatures trend below-normal behind a cold front Thursday
  night bringing low chances for light diurnal showers and
  perhaps a bit of lake effect rain/snow mix for
  Friday/Saturday.

&&

.SHORT TERM /THROUGH THIS EVENING/...
Issued at 200 PM EDT Tue Apr 16 2024

A deep 990mb surface low continues to spin over northeast NE this
afternoon, with a tight pressure gradient developing across
Midwest/upper Great Lakes ahead of it as a 1028mb Hudson High
remains sprawled out over Ontario. This is resulting in
strengthening southerly flow across the Midwest (see the RAP
analysis for an 850mb LLJ at 55+ kts!) and robust warm air advection
into the region. This in turn will bring rain into the area by the
evening, but the rain shield so far remains off to our southwest
across southeast MN.

High clouds continue to stream into the UP ahead of the approaching
system , but this seems to be having a pretty limited impact on
temperatures so far. Most of the area is reaching well into the 50s,
though across the Keweenaw and nearer to the shorelines of the Great
Lakes (mainly where easterly flow is onshore), temperatures may only
peak in the upper 40s and lower 50s this afternoon. Our well-mixed,
dry environment also seems to be winning out over cloud cover in
terms of dewpoints this afternoon; dewpoints are plummeting into the
teens and lower 20s across most of the UP away from the lakeshores.
Winds are on the increase across the UP this afternoon, already
gusting up to 20-30mph across the western half of the UP. As we head
into the late afternoon and evening, ensemble guidance shows around
a 60-80% chance for some spots throughout the western UP to gust
higher to 35mph - highest chances across the Keweenaw, where there
are also high probabilities (80%+) for gusts to 40mph. Winds can be
overdone at times in the hi-res guidance, but will still be
comfortable sticking with these advisory-level gusts given the look
of soundings tapping into those higher winds aloft. With elevated
fire weather conditions, particularly along the MI/WI state line,
don`t burn!

Otherwise, rain still looks to hold off until closer to 00Z, but a
few showers may begin to approach the MI/WI border and western Lake
Superior before sunset.

&&

.LONG TERM /TONIGHT THROUGH TUESDAY/...
Issued at 458 PM EDT Tue Apr 16 2024

The primary weather maker for the extended period is the 990 mb low
analyzed over northeast Nebraska at 3 PM EDT. This system brings two
distinct waves of rain 1) tonight and 2) later on Wednesday.
Additionally, strong east-southeast winds gusting to around 45 mph
are expected on the Keweenaw and across the eastern UP late tonight
until after the second round of rain later on Wednesday. We dry out
Wednesday night and Thursday ahead of a reinforcing cold front
Thursday night, which brings additional rain shower chances. The
cold core upper level low stays overhead Friday into Saturday
bringing chances for diurnal showers and perhaps a bit of lake
effect precip too.

Beginning with tonight, rain chances ramp up quickly as the systems`
warm front approaches from the southwest. I expect showers to reach
the Wisconsin state line around 10 PM - 12 AM then reaching a line
from Houghton-Marquette-Manistique about 2 hours later then the far
east about around 3-5 AM. The boundary layer appears to stay quite
warm, dry, and breezy until rain arrives. Once the rain arrives, a
sharp boundary layer inversion develops raising questions about how
windy it will be tonight. The ~40 mb gradient between surface
ridging over James Bay and the low pressure to our southwest
combined with a 50-60 kt LLJ are impressive. Other than being stable
with rainfall, I couldn`t come up with any good reasons to change
the wind advisory since ensembles and model soundings continue to
support the likelihood of gusts reaching criteria. There should
be a break in rain chances Wednesday morning before the next
round of rain arrives. The possible exception to that is near
Lake MI where east-southeasterly flow off the lake may result in
upslope drizzle. Regardless, the next round of rain arrives
during the early afternoon and continues into Wednesday night
when a cold front moves through and scours out remaining
moisture.

The post-frontal air mass is considerably drier and may result in a
nice day of weather for Thursday with the GFS advertising deep
mixing to 6-7 kft away from Lake Superior implying more fire wx
concerns. A reinforcing cold front moves through Thursday night with
modest cold air advection resulting in steep low level lapse rates
through Friday. Additionally, isolated rain showers cannot be ruled
out along the front, especially across the eastern UP. By Friday,
chilly conditions are expected due to blustery west winds possibly
reaching up to near 40 mph. The final surface trough moves through
Friday night shifting winds more NWerly and bringing a chance for
some light lake effect rain/snow mix. This potential appears to
coincide with a decaying deformation zone pivoting across the area.
Regardless, QPF appears light so not expecting impacts at this time.

Temperatures stay below normal on Saturday, but a warming trend
begins with any lake effect potential ending during the day. The
next weather-maker appears to arrive next Monday night implying
successively warmer temps Sunday and Monday. Given the time of year
and expected dryness of the incoming air mass, fire wx concerns seem
likely to return. The weather-maker next Monday night appears
clipper-ish and somewhat moisture starved so only expect light rain
showers at this time.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 127 AM EDT Wed Apr 17 2024

As the first band of light to moderate rain showers moves through
early this morning, expect the conditions to tank to IFR across the
TAF sites before a second wave of light to moderate rain showers
moves through the U.P. after dawn. Behind this second wave, we could
see scattered light rain showers, with vis and cigs bringing
conditions down to LIFR across all of the TAF sites by this
afternoon. Expect a slow improvement in terminal conditions
beginning late in the TAF period. Meanwhile, LLWS is being realized
across the TAF sites this morning and looks to continue until around
12z.

&&

.MARINE...
Issued at 458 PM EDT Tue Apr 16 2024

Northeasterly gales up to 45 kt are occurring across far western
Lake Superior this afternoon with sub-gale force gusts elsewhere.
Easterly gales up to 45 kts spread across Lake Superior tonight and
continue through Wednesday as a 991 mb low currently over Nebraska
approaches the lake. On Wednesday, the strongest winds are expected
over the north central and east half of the lake as gales subside
across the western lake. Probabilities of storm force gusts to 47
kts remain low at less than 15%. Winds fall below gale force as the
low pressure moves onto the lake late on Wednesday. Generally stable
conditions persist over the lake limiting additional periods of high
winds, but the enhanced pressure gradient should keep westerly gusts
of 20-30 kt from late Wednesday night through Friday. Significant
wave heights up to 10-13 feet are expected across the far east this
evening before 8-12 feet waves spread across the whole lake on
Wednesday. Locally higher waves up to 16 feet are possible between
Isle Royale and the tip of the Keweenaw Peninsula Wednesday morning
and afternoon.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
  Wind Advisory until 5 PM EDT this afternoon for MIZ001-003-006-
     007-014-085.

Lake Superior...
  Gale Warning until 2 PM EDT /1 PM CDT/ this afternoon for
     LSZ162-263.

  Gale Warning until 8 PM EDT this evening for LSZ243>246-250-
     264>266.

  Small Craft Advisory until 8 AM EDT /7 AM CDT/ this morning
     for LSZ240-241.

  Gale Warning until 8 AM EDT this morning for LSZ242.

  Small Craft Advisory until 8 PM EDT this evening for
     LSZ247>249.

  Gale Warning until 8 PM EDT this evening for LSZ251-267.

Lake Michigan...
  Gale Warning until 2 PM EDT this afternoon for LMZ221-250.

  Gale Warning until 8 PM EDT this evening for LMZ248.

&&

$$

SHORT TERM...LC
LONG TERM...EK
AVIATION...TAP
MARINE...EK