761
FXUS63 KAPX 030357
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
1157 PM EDT Tue Jul 2 2024

.KEY MESSAGES...

- A few thunderstorms producing locally heavy rain at times
  tonight.

- Trending dry for the Independence Day holiday (Thursday).

- Heavy rain and possible stronger storms return for the weekend.

&&

.UPDATE...
Issued at 1053 PM EDT Tue Jul 2 2024

Current forecast remains on track as rain with embedded
thunderstorms is beginning to spread across northwest lower and
areas near Saginaw Bay. As noted in the short term discussion below,
convective cores within this activity may lead to locally heavy
rainfall tonight in the midst of an environment supportive of
efficient rain (PWATs near 1.7" on this evening`s 00Z launch).
Heaviest rainfall overnight is anticipated across northwest lower
and eastern upper Michigan where localized amounts over 1" will be
possible. However, most areas are more likely to see around 0.5" by
Wednesday morning. Rain chances will diminish from west to east
during the morning hours, leaving mostly sunny skies in place
by the afternoon.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 259 PM EDT Tue Jul 2 2024

Pattern Synopsis/Pattern Forecast:

Increasingly moisture rich southwest flow overspreading the area
early this afternoon...with northern Michigan sandwiched between
Gulf States centered subtropical ridge and broad troughing slicing
east across central Canada into the northern Plains. Initial wing of
moisture advection into the region mostly of the elevated type, with
stubborn to yield low level dry air remaining the main detriment to
more widespread rain this afternoon. Juxtaposition of better deep
layer moisture advection and a more unstable atmospheric profile
remains just a bit upstream, and that indeed is where the most
organized and intense rain has remained.

Upstream troughing and embedded shortwave will continue to work east
into the western Great Lakes tonight into early Wednesday. Attendant
cold front will lead the charge, bringing with it a more organized
rain threat tonight.

Primary Forecast Concerns/Challenges:

Main focus and shower and thunderstorm evolution and possible heavy
rain threat tonight.

Details:

Low level jet forced moisture advection will only increase with time
this evening into the overnight, sending precipitable water values
to over an inch and a half. Isentropic upglide will become maximized
on the nose of this 50+ knot southwest low level jet, with pattern
recognition strongly supporting an expanding area of rain within
this forced ascent axis. While primary corridor of instability folds
south with time, just enough elevated instability looks to remain to
produce at least some embedded non-severe thunderstorms. Given
available moisture through a deep layer of the atmosphere and what
appears to be an appreciable warm cloud depth, we should see some
rather respectable rainfall rates...especially with any deeper
convective cores. Axis and orientation of low level jet argues for a
relatively narrow corridor of heavier rain potential. Still some
discrepancy where this axis will center itself, but trends generally
support tip of the mitt counties into eastern upper Michigan for
heaviest rain potential. Wouldn`t be terribly surprised to see an
inch or more where this axis lines up. Enough to produce some local
ponding on roads and in poor drainage areas, but otherwise no
significant impacts expected. Definitely a mild night, with most
areas not falling out of the 60s.

Front sweeps rapidly east of the area Wednesday morning, ending the
rain threat for most in the process. Post-frontal west synoptic flow
definitely supports the all to typical lake breeze convergence
corridor across central upper Michigan during the afternoon.
Lingering moisture looks more than adequate to potentially kick off
a few showers and perhaps isolated thunderstorms in this region
during the afternoon. Post-frontal cold air advection far from
impressive, helping temperatures recover into the upper 70s and
lower/middle 80s during the afternoon.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/...
Issued at 259 PM EDT Tue Jul 2 2024

PATTERN SYNOPSIS/FORECAST:

Longwave troughing swinging through the area will keep the Great
Lakes Region active throughout the long-term. A shortwave trough
will track overhead late Thursday night into Friday, increasing
higher to mid level clouds ahead of a deepening low pressure system
that will track into the region for the weekend.

PRIMARY FORECAST CONCERNS:

- Independence Day: A shortwave trough will track overhead Thursday
evening. Looking at forecast soundings, it appears that the
atmosphere will be too dry in the lower levels to support rainfall
on Independence Day. However, clouds will build in later in the
evening in response to the aforementioned shortwave. Mainly Westerly
winds will create a downsloping component across Northeast lower,
making temperatures warmer in these areas (mid 80s) compared to
elsewhere in Northern Michigan (high 70s to low 80s).

- Weekend Precipitation Chances:  Attention then quickly turns to a
trough and its associated low pressure digging across the Midwest
and into the Great Lakes Region for Friday/ Saturday. Current
guidance continues to show moderate instability and a relatively
deep moisture fetch (PWATS above 1.2") into the region for this
weekend. The most favorable day for possible strong to severe?
storms to develop will be Friday, but showers are expected to
continue through most of the weekend and an embedded rumble of
thunder or two cannot be ruled out. Stay tuned as we continue to
fine tune these details!

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1156 PM EDT Tue Jul 2 2024

Rain and embedded rumbles of thunder continue to spread across
northern Michigan as associated CIGs will lower tonight, and are
expected to drop to MVFR across most of the area shortly after 06Z.
IFR CIGs are also anticipated for many areas late tonight into
Wednesday morning. Brief drops to MVFR VSBYs will be possible within
heavier rainfall. Strong winds just off the surface lead to the
inclusion of LLWS across all northern lower Michigan TAF sites into
Wednesday morning. Cloud cover will clear from west to east as rain
chances depart Wednesday morning, leaving VFR conditions in place
from late morning/early afternoon Wednesday through the end of the
issuance period.

&&

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

&&

$$

UPDATE...DJC
SHORT TERM...MSB
LONG TERM...NSC
AVIATION...DJC