360
FXUS63 KMQT 202056
AFDMQT

Area Forecast Discussion
National Weather Service Marquette MI
456 PM EDT Thu Jun 20 2024

.KEY MESSAGES...

- Widespread rain chances still seem likely for the first half
  of weekend with latest guidance trending southward with the
  axis of heaviest accumulations.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 252 PM EDT Thu Jun 20 2024

Generally tranquil weather will persist through tonight. Surface
ridging over Lake Superior is allowing for light onshore flow along
the shoreline keeping temperatures in the 50s along the immediate
shore to 60s inland. Where sun has been prevalent over the eastern
U.P., temperatures have climbed into the 70s.  A weak disturbance
aloft lifting northeast in the southwesterly flow aloft is producing
widespread mid-level clouds over the western half of the area with
even a few sprinkles. Much drier air in the sub cloud layer,
however, is causing many of the returns being seen on radar to
evaporate before hitting the ground. Not many changes are expected
through the night. Best chance for enough sprinkles or light showers
to wet the ground will be over the far west and along the WI border
through the early evening.  Temperatures will be seasonable tonight
around 50 and into the lower 50s with clouds keeping temperatures
from falling too much despite light winds.

&&

.LONG TERM /FRIDAY THROUGH THURSDAY/...
Issued at 456 PM EDT Thu Jun 20 2024

This weekend will be an active period as troughing currently over
the western U.S. coast moves east through the Great Lakes. A brief
dry period starts Sunday evening continuing through Monday, but
another trough progressing east through Canada early next week
brings a round of shower and storm chances for Monday night/Tuesday.
A drier pattern then sets up for the rest of next week. The CPC`s 6-
10 day precipitation outlook reflects this extended forecast well
with 40-50% chances for above normal precipitation for the entire UP.

Starting Friday, sfc high pressure will diminish and WAA will touch
off some light to moderate showers along the WI/MI state line in the
west mid to late morning. Showers expand northeast across the UP
throughout the day as a warm front lifts through southern WI and a
shortwave rides over the UP. The best chances for showers are
expected in the later part of the afternoon in the southwest and
south-central UP; areas closer to the frontal boundary. Model
soundings show a decent cap and instability is lacking (MUCAPE
around or below 100 J/kg late Friday afternoon through Friday night
along the WI/MI state line and in the south-central UP). So a few
rumbles of thunder are possible, but strong storms are not expected.
The warm front is progged to stall across central WI Friday night as
a sfc low lifts northeast from the Central Plains into southern MN
by Saturday morning. Meanwhile, moisture will increase Friday night,
continuing through Saturday with PWATs around 1.6" to 1.9" (highest
south-central during that period).

The main shortwave passes east over the Upper Great Lakes Saturday
and Saturday night with the sfc low deepening as it follows
northeast through the Upper Great Lakes. As the low moves northeast,
the warm front lifts with it and drags along the northern end of
Lake MI; this is where the axis of heaviest rainfall is expected.
Latest guidance has trended this axis southward and diminished event
total QPF, but this still will be a wet period for the area. Total
QPF Friday through Saturday is around 0.5" in the Keweenaw,
increasing southeastward to 1" across the UP with higher amounts to
2" possible in the south-central and southeastern UP along Lake MI.
This is a 0.5" to 1" decrease from the previous forecast package
with the southward trend. Also with this southward trend, the
Keweenaw may not see any measurable precip until Saturday morning
when the low lifts through the area. The SPC slight risk reaching
into the western UP for Saturday seems a bit high considering the
6/20 12Z LREF probs of at least 500 J/kg of CAPE are around 20-40%,
but some embedded thunderstorms are possible along the passing
frontal boundary with bulk shear ~35-40 kts.

Another trough dives southeast over the area on Sunday bringing an
additional round of showers and possibly some thunder. However,
model soundings are rather moisture starved and instability remains
fairly low, so showers should be light and strong storms are not
expected. A brief dry period then follows through early next week as
weak ridging and high pressure moves southeast over the area. The
next round of showers and storms arrives late Monday night/Tuesday
as a trough moves east through northern Ontario.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 143 PM EDT Thu Jun 20 2024

VFR conditions will prevail for most of the TAF period with light
easterly winds. Ceilings will begin to lower at IWD very late in the
period possibly approaching IFR just beyond 18Z tomorrow. Light rain
chances will also increase at IWD towards the end of the TAF
period.

&&

.MARINE...
Issued at 456 PM EDT Thu Jun 20 2024

A stretch of light north to northeast winds mainly below 15 kts is
expected through early Saturday with surface high pressure over Lake
Superior. This high pressure weakens through Friday and a surface
low lifts northeast through the Upper Lakes Saturday and Saturday
night. This results in northeasterly winds to around 20 kts over the
west half of the Lake during the day Saturday. Northwesterly winds
behind the departing low should stay around or below 20 kts on
Sunday. South winds return on Monday veering southwest Monday night
and increasing to 20-25 kts ahead of another weak cold front by
Tuesday afternoon.

&&

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

&&

$$

SHORT TERM...MZ
LONG TERM...Jablonski
AVIATION...MZ
MARINE...Jablonski