000
FXUS63 KMQT 162100
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
500 PM EDT Tue Apr 16 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 /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 200 PM EDT Tue Apr 16 2024

VFR prevails at all TAF sites through this evening with just some
high clouds streaming through the area. Tonight, an advancing low
pressure out of the Plains will cause widespread -SHRA. Ceilings
lower to MVFR at all terminals, and MVFR or IFR visibility will be
possible at times in light to moderate SHRA (40-60%). Ceilings lower
further to IFR into tomorrow morning, most likely at CMX and SAW
(80+%) compared to IWD (60%). After a brief break in rain showers
during the morning, another round of rain moves in for the afternoon
with MVFR to IFR visibility. As the low approaches tonight, E and
ESE winds will be gusty, with IWD seeing gusts up to 35 kt and CMX
seeing gusts up to 45 kt. An advancing low level jet will create a
LLWS threat at all sites tonight, ending during the morning.

&&

.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 from 2 AM to 5 PM EDT Wednesday for MIZ001-003-
     006-007-014-085.

Lake Superior...
  Gale Warning from 11 PM this evening to 8 PM EDT Wednesday for
     LSZ243>246-250-264>266.

  Gale Warning until 2 PM EDT /1 PM CDT/ Wednesday for LSZ162.

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

  Small Craft Advisory until 11 PM EDT this evening for
     LSZ242>246.

  Gale Warning from 11 PM this evening to 2 PM EDT Wednesday for
     LSZ242-263.

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

  Gale Warning from 4 AM to 8 PM EDT Wednesday for LSZ251-267.

Lake Michigan...
  Small Craft Advisory until 8 PM EDT this evening for LMZ221-
     250.

  Gale Warning from 8 PM this evening to 2 PM EDT Wednesday for
     LMZ221-250.

  Small Craft Advisory until 11 PM EDT this evening for LMZ248.

  Gale Warning from 11 PM this evening to 8 PM EDT Wednesday for
     LMZ248.

&&

$$

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