200
FXUS63 KMQT 300521
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
121 AM EDT Thu May 30 2024

.KEY MESSAGES...

- Widespread frost expected tonight across much of the UP away
  from the shores of the Great Lakes. Localized hard freezes
  can`t be ruled out but is not expected to be widespread.

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

- A more unsettled pattern returns on Friday, continuing into
  next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 230 PM EDT Wed May 29 2024

GOES Visible imagery shows a near-perfectly clear sky over the
UP today with fair weather cu staying to the south and west of
the UP. This is caused by a RAP-analyzed 1025mb high pressure
centered over west-central Lake Superior this afternoon,
supported by ridging aloft over the Great Plains. High temps
this afternoon in response to the clear skies will climb into
the 60s for much of the interior UP, though lingering northerly
wind gusts will keep the Lake Superior shores in the 50s.

Overnight, clear skies will continue. With a well-mixed airmass that
has already seen RHs falling into the 20s, radiational cooling is
expected to be quite efficient. However, various rules of thumb
point to temperatures only reaching around freezing or just above
freezing, with MOS guidance trending warmer with recent model runs.
Forecast lows overnight are now forecast to be as low as 30F as a
result, though it would not be a surprise for the typical cold spots
in valleys and other low-lying areas to have hard freezes. While
hard freezes will be limited to localized areas, frost should be
widespread in the early morning areas for all of the UP away from
the shores of the Great Lakes.

&&

.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
Issued at 409 PM EDT Wed May 29 2024

The quiet and dry period ends on Friday as a cold front moves into
the west. This is followed by precip chances for the weekend into
early next week as we track out shortwaves into the Upper Great
Lakes. Temperatures warm through the early part of next week as
ridging shifts toward the Atlantic coast and WAA increases.

Starting on Thursday, high pressure continues to shift southeast
over the Great Lakes Basin as mid level ridging builds in. This
results in more mixing and dry conditions similar to today. While
mixing is not expected to be as high (mixing to around 4-6kft),
highs are expected to be warmer in the upper 60s to mid 70s in the
interior with cooler 60s by the Great Lakes lakeshores. This brings
min RHs in the interior into the 20s, higher near the lakeshores (30-
40%). Light southerly winds are forecast save for some east winds in
the Keweenaw and the varying wind directions near Lake Superior as a
lake breeze pushes in off the lake during the afternoon. The warm
and dry conditions flirt with borderline elevated wildfire criteria
with winds being the limiting factor as gusts are mainly expected
below 15 mph. Skies stay mostly clear Thursday night with lows in
the low 40s to low 50s, warmer in north central and western Upper MI
where there is southerly downslope flow.

A weak cold front associated with a sfc low over northern
Saskatchewan moves into the western UP on Friday. This brings in a
band of showers over the west on Friday, but not much eastward
progression is expected as the front weakens and stays relatively
stationary. Chances for thunderstorms on Friday remain low (>15%)
with minimal instability (high-end of MUCAPE guidance around 100-200
J/kg), lower bulk shear (25-30 kts), and a weakening frontal
boundary. Where precip holds off and skies remain clearer over the
east on Friday, mixing could result in borderline wildfire
conditions with gusts to 20 mph and minimum RHs back into the 20s.

Chances for showers increase Friday night into Saturday as a
shortwave lifts northeast from Iowa through the Upper Great Lakes
and isentropic ascent increases. This will be quickly followed up by
another shortwave tracking east from the Northern Plains Friday
night through Lake Superior Saturday into Saturday evening. Better
chances for thunderstorms accompany the secondary shortwave on
Saturday when there is better instability and shear. A brief dry
period is expected to follow into Sunday as we warm into the upper
60s to upper 70s.

The rather active weather pattern continues into early next week
with an additional shortwave expected to pass over Lake Superior and
Upper Michigan on Monday ahead of a deeper trough for mid next week.
That said, accumulations are not expected to be high as 5/29 0z LREF
probabilities of at least 0.25" of QPF in a 24 hour period stay
below 50%. With spread in the guidance among timing and track of the
shortwaves, opted to leave NBM PoPs as is.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 121 AM EDT Thu May 30 2024

Under high pressure, VFR will prevail at all TAF sites.

&&

.MARINE...
Issued at 409 PM EDT Wed May 29 2024

High pressure slowly shifts southeast over the Great Lakes Basin
into this weekend. This leaves light and variable winds mainly below
15 kts through Thursday morning. Winds become easterly Thursday
morning, veering south Thursday evening. South winds then increase
to 10-20 kts through Friday as a weak low level jet passes overhead.
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...
  Frost Advisory until 10 AM EDT /9 AM CDT/ this morning for
     MIZ002-004>007-009>014-084-085.

Lake Superior...
None.
Lake Michigan...
None.

&&

$$

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