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000
FXUS63 KMQT 170728
AFDMQT

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

.KEY MESSAGES...

- A low pressure passing through the Upper Peninsula today will
  bring with it wind gusts in excess of 45 mph in the eastern
  third and western Keweenaw Peninsula
- Additional rainfall totals of a half inch to inch are expected
  (50+%), highest from Escanaba to Newberry
- 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 TONIGHT/...
Issued at 326 AM EDT Wed Apr 17 2024

GOES-16 WV imagery and radar reflectivity show multiple bands of
precipitation passing through the UP from the southwest this
morning. RAP analysis shows a 994mb low over the Iowa/Minnesota
state line on a weakening trend as it approaches the Upper Great
Lakes basin today. As the low is contrasted with a 1030mb Hudson Bay
high, the enhanced pressure gradient is causing some windy
conditions at some UP and Lake Superior sites. HREF wind
probabilities show near 100% probability of frequent wind gusts over
45 mph for the eastern third of the UP through the early afternoon
hours as well as on the west-facing slopes of the Keweenaw
Peninsula. In addition to the surface gradient, an 850mb LLJ of
around 55 kt is passing over the UP this morning, which BUFKIT
soundings show that some areas may see sufficient mixing to tap into
that jet to some extent. Therefore, the ongoing Wind Advisory will
continue as-is for this forecast package, and if any adjustments are
made, they will likely come after the upcoming 12Z HREF guidance is
available.

As the low pressure passes over the UP today, some dry slots
between bands of precip will cut into precip totals somewhat,
as the 00Z HREF shows a mean of around 0.5 inches of QPF still
to come across most of the UP through early Thursday morning,
with higher amounts closer to 1 inch more likely in a band from
Escanaba to Newberry. A few rumbles of thunder cannot be ruled
out throughout the day in Menominee County as HREF maximum CAPE
values rise to 100-200 J/kg, though impacts should be minimal.
Tonight, expect showers to end from southwest to northeast
starting around midnight and with showers ending nearly
completely by 12Z Thursday as pressure rises behind the
departing surface low. Winds will fall below advisory criteria
in the evening as the low weakens to above 1005mb per the GFS,
significantly slackening the pressure gradient.

&&

.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-
     251-264>267.

  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.

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...GS
LONG TERM...EK
AVIATION...TAP
MARINE...EK