555
FXUS63 KAPX 042300
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
700 PM EDT Tue Jun 4 2024

.KEY MESSAGES...

- Scattered to numerous thunderstorms on Wednesday.

- Unseasonably cool with shower chances late week into weekend.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 208 PM EDT Tue Jun 4 2024

Pattern Synopsis and Forecast:

Potent, elongated and or messy, upper trough and subsequent low
pressure system centered over southern Saskatchewan-Manitoba will be
the focus for this upcoming period. Southern short wave either
associated with, or advecting along the southern periphery of the
parent upper low, will swing through the Great Lakes Region
during the day on Wednesday. This short wave, warm (very) moist
advection early on Wednesday, and an approaching cold front will
facilitate an environment favorable for thunderstorm
development throughout the day as the parent upper low and sfc
low move east across southern Canada. Cooler temps on the way
behind this frontal system.

Primary Forecast Concerns:

Any isolated convection early this evening will diminish
shortly into the overnight hours. Next system in the form of a
short wave trough and cold front will move into the region
largely on Wednesday with scattered to numerous thunderstorms
thanks to dewpoints surging into the mid 60s, weak to modest
instability, and ample lift. Largely expecting these storms to
be general thunderstorms due to the combination of only modest
instability and shear but cannot rule out a stronger storm or
two with gusty winds. Progged soundings (and Plainview 2D maps)
do show PWATs well into the 1.5" to 1.8" range, which would
easily be a daily record according to the spc sounding
climatology page. In fact, model soundings show a very favorable
environment for efficient, heavy rain with these storms due to
the following: skinny CAPE, very high low to mid RHs (80-90%+),
and a relatively deep warm cloud layer. Only thing working
against this environment is the quicker storm motions, but any
training/additional development aside from along the cold front
could produce locally heavier pockets of rain. On the bright
side, this should be a good wetting rain for a good chunk of the
area. Not really too many other hazards/impacts with this
system other than lightning, pockets of heavy rain, and maybe
some isolated gusty winds, but temperatures will be on the
decline behind this frontal system.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 208 PM EDT Tue Jun 4 2024

Pattern/synopsis: An upper low, which initially develops over s
central Canada, will move/evolve into the Great Lakes area. And here
it will sit, and sit, and sit a little longer.

Forecast: Unseasonably cool and, at times, showery wx will persist
for the bulk of the long-term forecast. Thursday into Friday into
particular look soggy, as the upper low moves directly overhead.
This will combine with abundant moisture, and any contribution from
weak diurnal heating, to result in showers (and a few t-storms on
Thursday). Though the core of the upper low shifts toward Georgian
Bay and Lk Ontario this weekend, significant troffing lingers back
into the northern lakes. This will maintain some showers, with a
diurnal contribution/amplification in the afternoon and evenings. As
we head into early next week, the upper trof pivots toward the
southern lakes and northern OH Valley. That allows heights to start
to rebound, with temps starting to do the same, and eventually pops
will slacken.

How cool will temps be Fri/Sat? There is plenty of model guidance
that keeps readings in the 50s in at least the eastern UP and higher
elevations of northern lower MI. Most of our blends are a little
warmer than that. Any sort of diurnal heating at all will push
readings higher and fast (it is still June). The idea of a diurnal
temp swing of less than 10f seems kind of difficult...but we did
manage it just a week ago, on a rainy/cold advection Memorial Day.
Have taken max temps down a hair on Fri/Sat.

Min temps won`t depart too far from normal during the long term
period, but max temps will. Highs mid 60s to mid 70s Thu, but then
mid 50s to mid 60s Fri-Sat. Hopefully a gradual rebound after that,
with 60s Sun, near 70f Mon, in the 70s Tue.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 700 PM EDT Tue Jun 4 2024

A few showers and possibly an isold thunderstorm remains
possible thru tonight as low level WAA and moisture advection
continues across Michigan well in advance of an upstream cold
front. Widespread showers and thunderstorms will develop on
Wednesday as the cold front sweeps thru our state. Prevailing
conditions will remain VFR thru tonight...but will drop to MVFR
on Wednesday...and possibly IFR at times within some heavies
showers and storms. Surface winds will remain from the S/SE at
10 to 20 kts thru Wednesday.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...None.

&&

$$

SHORT TERM...JLD
LONG TERM...JZ
AVIATION...MLR