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000
FXUS63 KMQT 180700
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
300 AM EDT Thu Apr 18 2024

.KEY MESSAGES...

-Cooler temps Friday and Saturday with low (30%) chances for
 light rain showers this afternoon/evening and perhaps a light
 lake effect rain/snow mix for Friday/Saturday.
-Localized fire wx concerns could resurface again Friday into
 Saturday with more widespread concerns emerging by Sunday and
 Monday as a drier airmass moves in with breezy W to NW winds.

&&

.SHORT TERM /THROUGH THIS AFTERNOON/...
Issued at 259 AM EDT Thu Apr 18 2024

GOES-16 Channel 10 Water Vapor imagery shows the stacked low
pressure that has driven rainfall over the last day or so over the
Upper Peninsula. That feature, now at 1006 mb and weakening, will
exit the eastern end of Lake Superior throughout the morning,
leaving surface pressure rises and shortwave ridging aloft in its
wake. However, any clearing behind the low`s departure will be brief
as wraparound moisture from the low will help clouds linger as well
as clouds streaming northeast from a shortwave trough exiting the
Central Plains. The broad trough associated with this shortwave is
based over the Canadian Prairie this morning and that trough will
shift east today, sending various rounds of PVA towards the UP
today. A few light rain showers are the result, with the 00Z HREF
showing the chance of measurable rain ranging from 30-70% mainly in
the central UP bounded to the west by Baraga and to the east by
Manistique. Hourly PoPs are a bit harder to nail down as each
ensemble member resolves the light showers slightly differently, but
the highest chances for any given hour seem to be mainly in the
Menominee area at 15-20% prior to 21Z before overspreading the rest
of the central UP (20-40%) from 21Z-00Z this evening. The absolute
maximum rainfall totals prior to 00Z in the HREF look to be around
0.2 inches, with ensemble means at only a couple hundredths, so
impacts should be minimal. A slackening pressure gradient will make
for lighter winds today, with a few hi res models even showing a
brief lake breeze off of Lake Superior, though not penetrating far
inland. Patchy fog has been observed in the wake of the low with
METARs from CMX varyiung wildly between 1/4SM and 4SM visbility much
of the night already. The fog will likely be gone after sunrise as
by 12Z this morning, HREF probability of visibility 1/2SM or less is
only 20% on the upslope areas of the Keweenaw Peninsula.

&&

.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
Issued at 525 PM EDT Wed Apr 17 2024

Overall, the extended period is characterized by mostly quiet
weather save for a few low-end chances for light precip (mainly
rain). Cold air advection behind Thursday night`s cold front passage
leads to deep mixing within westerly flow that is favorable for
strong winds on the Keweenaw. Model soundings dry out on Saturday
and stay dry through early next week while still advertising deep
mixing leading to a return of fire wx concerns. Temps for the entire
extended period should average near to above-normal, but Fri thru
Sat night will be chilly before moderating ahead of a system
tracking across the region Monday night or Tuesday.

Starting with Thursday morning, the area should be dry and in-
between features of interest. A modest cold front moves through late
on Thursday with cold air advection aloft decreasing stability
throughout the day. By afternoon/evening model soundings advertise
potential for diurnal showers developing with equilibrium levels
around ~10kft. Not expecting much in the way of precipitation with
this but isolated afternoon showers seem like a good bet. A drier
post-frontal air mass ends rain chances and should also allow for
clearing skies. This should allow low temps to dip to near the
freezing mark.

Friday into Saturday appears to be the most active period of
weather as the upper level low moves overhead. Almost due west
winds are expected on Friday which raises concerns about 1)
strong gusts on the Keweenaw and 2) fire wx potential with
temperatures/winds possibly exceeding guidance elsewhere within
a very deeply mixed boundary layer (perhaps up to ~9 kft at
IMT/MNM/ESC). The primary limiting factor appears to be
sufficient low level moisture for a robust cumulus field,
possibly including another shot at diurnal showers. Away from
Lake Superior, a 5kft deep inverted-v suggests rain drops will
struggle to reach the ground without a fairly robust shower.
Closer to Lake Superior, isolated to scattered showers are
expected by Friday night as deeper synoptic moisture moves into
the area. With wet bulb temps around freezing there`s a good
chance for snow to mix in if not completely change-over,
especially at higher elevations of the traditional WNW to NW
wind snow belts. Potential for lake enhanced showers continues
into Saturday morning (west) and afternoon (east) before
synoptic moisture departs to our east. QPF amounts stay light so
snowfall is unlikely to cause impacts. Drying appears to occur
late enough in the day for fire wx concerns to be delayed until
Sunday, but it`s something to keep an eye on especially south-
central where winds are downsloping.

Successively warmer days brings above normal temps back to the UP
for Sunday into Monday. Deep mixing continues except by Sunday we`ll
be mixing into a mid-level dry layer that is more favorable for fire
wx concerns. Winds could get gusty both Sunday and Monday afternoon,
but the wind fields appear slightly stronger on Sunday with gusts of
20 to 25 mph currently forecast. Models indicate the next wnw flow
shortwave will move through Mon night into Tue bringing the next
chance of rain showers. Given its west-northwest trajectory suspect
moisture inflow ahead of this shortwave will be somewhat limited so
only expect light rain showers at this time Mon night into Tue. It`s
worth noting that recent model guidance has trended toward a better
organized low pressure that may be capable of moderate precip
amounts, but ensembles indicate chances are still low around ~25%.
Models and ensembles advertise drier and somewhat cooler conditions
behind this shortwave into the middle of next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 127 AM EDT Thu Apr 18 2024

As the low lifts northeast from Lake Superior into Ontario early
this morning, expect a general trend towards improving conditions,
even though the TAF sites are currently MVFR/IFR/LIFR due to
low-level clouds and patchy fog. The conditions across the TAF
sites look to improve to VFR by late this morning as drier air
moves into the region behind the low. A shortwave low moving
from the Plains into the Midwest today could bring some light
rain showers back over KSAW this afternoon and evening; that
being said, KSAW looks to remain VFR this afternoon and evening.

&&

.MARINE...
Issued at 525 PM EDT Wed Apr 17 2024

East-southeast gales of 35 to 40 kts persist across much of north-
central and eastern Lake Superior late this afternoon. Gales subside
this evening as the weakening low pressure moves into eastern Upper
Mi later this evening. Generally stable conditions persist over the
lake tonight into early Friday morning with WSW winds gusting up to
25 kts. A cold front moves across the lake late Thu into Thu night
with decreasing stability supporting increasing up to near gale
force, especially north of the Keweenaw Peninsula. Another
front/trough crosses the lake late on Friday shifting winds west-
northwesterly with a few gale force gusts to 35 kts possible Friday
night and Saturday before subsiding by the afternoon or evening.
Otherwise winds back westerly and subside to 15 to 25 kts across the
lake Sat night thru Monday.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
  Small Craft Advisory until 8 AM EDT this morning for
     LSZ244>248.

  Small Craft Advisory until 11 AM EDT this morning for LSZ250.

  Small Craft Advisory from 8 AM this morning to 2 PM EDT this
     afternoon for LSZ251.

Lake Michigan...
None.

&&

$$

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