-- Discussion containing changed information from previous version are highlighted. --
630
FXUS63 KMQT 282325
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
725 PM EDT Tue May 28 2024

.KEY MESSAGES...

- Below normal temperatures through Wednesday night, then
  warming up through early next week.

- Areas of frost expected Thursday morning.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 241 PM EDT Tue May 28 2024

RAP analysis shows a 500mb shortwave axis over western Lake Superior
while the main surface features are a 992mb low over Quebec and a
1026mb high over Manitoba. Surface flow will be mainly northerly
through the forecast period, which will help keep the Lake Superior
shores in the 50s for highs today while the Lake Michigan shores
stay in the mid-60s. The shortwave approaching the western portions
of the UP this afternoon has been deamplifying much of today,
reducing the forcing available for showers. Persistent cloud cover
through the first portion of the day today has also limited diurnal
heating. These have factored into a reduction in the chances of
thunderstorms in the interior west and south today, though enough
CAMs have simulated reflectivity values above 40 dBZ near Menominee
to keep at least 15% chances of thunder along the WI/MI border in
Menominee County.

Overnight, a subtle shortwave will drop from the north over Lake
Superior overnight. While some model runs in the past 24 hours had
resolved showers here, the airmass descending onto the lake should
dry out the column as it approaches the UP. There is enough upslope
forcing to keep clouds in the forecast through the overnight period
for the central UP, but rainfall is not expected. This cloud cover
will act to reduce radiational cooling, with only isolated portions
of the interior west now expected to see patchy frost overnight.
Lows will mainly be around 40 tonight.

&&

.LONG TERM /WEDNESDAY THROUGH TUESDAY/...
Issued at 431 PM EDT Tue May 28 2024

The extended forecast starts off with a quiet and dry period through
Thursday night thanks to sfc high pressure and mid level ridging
moving through the region. This is followed by precip chances for
the weekend into early next week as we track out shortwaves into the
Upper Great Lakes. Temperatures are expected to be cooler than
normal through Wednesday night, warming through the early part of
next week as ridging shifts toward the Atlantic coast and WAA
increases.

Starting on Wednesday, mid level ridging will be centered over the
Northern Plains with a trough over the Pacific Northwest and a
closed low over northern Quebec. A shortwave departing southeast
from the area early in the morning with sfc high pressure building
in over the Upper Great Lakes will result in sunny skies for the
entire UP by mid morning. This sfc high pressure extending from
James Bay will also yield dry north flow to the UP with PWATs
dropping to around 0.25" to 0.3" by the end of the day. The 5/28 0Z
NAEFS indicates PWATs of these values are below the 10th
climatological percentile for our region. With model soundings
indicating mixing up to 800 mb in the interior and around 900 mb by
the lakeshores and in the east, min RHs Wednesday afternoon are
expected around 25-30%. This means the UP flirts with borderline
elevated wildfire conditions as the west is warmer with highs in the
mid 60s, but gusts stay mainly below 15 mph. Slightly cooler temps
are expected over the east in the 50s near Lake Superior to low 60s
in the interior with gusts approaching 15-20 mph. That being said,
the wet pattern we have observed over the last few days leaves
little fire weather concerns at this time.

PWATs continue to drop for Wednesday night (nearing the minimum of
the NAEFS climatology of 0.15" to 0.25") with sfc high pressure
continuing to build over the Upper Great Lakes. Good radiational
cooling will bring lows below normal into the 30s, coldest in the
interior. With near calm conditions, a dry airmass, and colder
temps, areas of frost are likely away from the Great Lakes
lakeshores late Wednesday night into Thursday morning.

Thursday sees more mixing and dry conditions similar to Wednesday as
mid level ridging builds in. While mixing is not expected to be as
high, temps are expected to be warmer in the upper 60s to mid 70s in
the interior with cooler temps by the lakeshores. This brings min
RHs in the interior into the 20% range, higher near the lakeshores
(30-50%). Winds are expected to be lighter (gusts mainly below 15
mph save for the Keweenaw), so wildfire conditions stay low.
Thursday night brings lows mainly in the 40s under mostly clear
skies.

PoPs return to the forecast on Friday as a weak cold front moves
into the west. With minimal instability (highest CAPE below 100
J/kg) and a weakening frontal boundary, mention of thunder was
removed from the forecast through Friday night. Chances for showers
and thunderstorms increase on Saturday as a shortwave moves from the
Northern Plains Friday night over just north of Lake Superior late
in the day Saturday with ridging shifting toward the Atlantic coast.
An additional shortwave lifts northeast from the Southern Plains
Friday into the lower part of the Great Lakes Basin for late in the
weekend. Another shortwave tracks east from the northern Rockies
Sunday night through the Great Lakes region Monday/Tuesday ahead of
a deeper trough for late next week. The rapid shortwaves progressing
through the region this weekend into next week yields a wetter
pattern for the weekend into early next week. That said,
accumulations are not expected to be high as NBM probabilities of at
least 0.1" of QPF in a 24 hour period for the most part stay below
50%. With spread in the guidance among timing and track of the
shortwaves, opted to leave NBM PoPs as is.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
-- Changed Discussion --
Issued at 715 PM EDT Tue May 28 2024

Expect VFR conditions to prevail in this forecast period at all
TAF sites under surface high pressure. The biggest threat to VFR
is a low-chance probability (around 20%) of some MVFR clouds
developing at SAW this evening. Isolated showers early this
evening are not expected to impact the terminals and are not
mentioned in the TAFs. Gusty northerly winds to 20 knots at SAW
will die down after sunset.
-- End Changed Discussion --

&&

.MARINE...
Issued at 431 PM EDT Tue May 28 2024

High pressure builds southeast into the Great Lakes through tonight,
slowly continuing southeast over the Great Lakes Basin into this
weekend. This leaves light northerly winds through tonight, mainly
below 20 knots; variable winds around 5 to 15 knots are expected for
Wednesday and Wednesday night. With probabilities of winds exceeding
22 knots below 20% through this weekend, winds are expected to
mainly remain below 20 knots into the early part of next week with
no major systems in the vicinity of Lake Superior.

&&

.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.

&&

$$

SHORT TERM...GS
LONG TERM...Jablonski
AVIATION...Voss
MARINE...Jablonski