146
FXUS63 KAPX 160131
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
931 PM EDT Sat Jun 15 2024

.KEY MESSAGES...

- Increasing potential for showers/storms tonight and especially
  Sunday.

- High heat and humidity to kick off the week.

- Some shower/thunder potential at times into next weekend.

&&

.UPDATE...
Issued at 931 PM EDT Sat Jun 15 2024

Warm/moist advection continues to increase in over the western
Great Lakes, in the wake of high pressure over the eastern
lakes. A surface warm front is seen along the IA/MN border, and
across far southern WI and southern Lake MI. Precip coverage is
increasing north of the front, in parts of WI and MN. Frankfort
MI has recently reported light rain, though it man not be much
more than a sprinkle. Still, given radar/ob/near-term guidance
trends, have trended the forecast a bit wetter. Chancy pops
initially in nw lower MI will gradually expand northward and
increase, with the most significant rain (in this forecast
area) expected overnight in western Chip/Mack Cos in eastern
upper MI.

Min temps from lower 50s to low 60s, warmest near Lake MI.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 337 PM EDT Sat Jun 15 2024

PATTERN SYNOPSIS/FORECAST:

High pressure slowly departing northeast this afternoon. Lingering
mid clouds across the EUP with the weak PV niblet slipping through
up there. More widespread clouds upstream over WI in advance of PV
max located over S. IA/N. MO; some radar returns over central WI,
though unclear how much of this is reaching the ground attm. Worth
noting that some mid-level clouds starting to develop to our south
over Lake MI/MKG as high clouds and weak bit of energy (possibly
some longwave gravity waves?) move into the region.

Expecting PV niblet over IA/MO to continue to slip northeastward
into WI tonight; bit of energy ahead of this should try to pivot
through here overnight, though unclear if anything will actually
make it to the ground in our CWA with this...though not impossible.
Setup late tonight into Sunday appears quite favorable for upstream
MCS development, as 700mb cap builds in as close as IA/western
WI...with strengthening SSW/SW-ly LLJ advecting weaker stability off
this atmospheric plateau, amid an increasingly moist and unstable
environment. Question remains, how quickly will this reach our CWA?
Could depend on how things evolve tonight/Sunday morning...as well
as how the pattern ultimately sets from our west into the region.

Primary Forecast Concerns:

Increasing potential for showers/storms tonight and
especially Sunday...

As mentioned above...pattern setup favors upstream MCS
development...though questions remain as to exactly how/where this
will occur. First, appears we may have to watch for an initial bout
of warm advection nonsense into the region late tonight (9-
12z)...which will be fighting against the dry air mass in place
attm. Bonus is that this could serve to prime the mid/low levels in
our area for the next round of activity expected to slide in with
the niblet itself Sunday afternoon...and this assumes the timing
works out as such, with two distinct areas of convection as opposed
to nuisance convection turning to nuisance decaying convection,
which isn`t impossible. However... any activity that develops in the
afternoon could become somewhat interesting, given that this is when
the best theta-e advection off the upstream ridge appears to occur,
and should also have better synoptic support with the PV anomaly
itself. May need to keep an eye out for some training
development/hydro concerns? We`ll see how it all pans out; we may
not fully know till we start to see the whites of its eyes tonight.

Aforementioned morning junk will throw a wrench in the
forecast, with the possibility that all of the activity ends up less
bullish and remains broadly north...or, if far enough north (which
would allow for better diurnal heating near the M-55 corridor),
could allow for a secondary area of convection to initiate in the
afternoon...though we will have a cap in place around 800mb which
could be problematic for storm development. Bulk shear values around
30-40kts could be supportive of storm organization with anything,
though think the best threat would be for hail, given that storms
/should/ be elevated. To be honest...max instability (esp in the
form of MUCAPE) appears to remain to our west through the
period...though instability should be on the increase during the
later afternoon to support at least some kind of activity trying to
make it in. Do have to wonder if morning convection will mess up
diurnal heating potential for parts of our area...so will have to
keep an eye on this. For now...think the greatest chances for storms
will be the EUP and areas more or less west of I-75-ish, closer to
the forcing/BCZ and better moisture/instability.

BOTTOM LINE...Sunday`s forecast remains very unclear beyond broadly
that it should be warm/humid with some kind of activity during the
day.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 337 PM EDT Sat Jun 15 2024

Pattern Synopsis/Pattern Forecast:

No doubt remains...anomalously strong subtropical ridge set to
mature across the eastern Conus early this week. Direct surge of
warm air advection between this ridge and broad western troughing
set to deliver quite the warm and humid airmass into the Northwoods.
Some hints that above pattern will attempt to break down as we head
into the mid and end portions of the week as upstream trough axis
shears northeast with time.

Primary Forecast Concerns/Challenges:

Again, main focus centers on upcoming heat and humidity...with a
secondary concern remaining on shower and thunderstorm potential.

Details:

Complete analysis of low level thermal profiles continue to support
much of northern lower Michigan making a run into at least the lower
90s both Monday and Tuesday afternoons....with readings a bit cooler
near those big waters and north of the Straits. Uncertainty has only
increased beyond this period...all dependent on just how fast this
amplified pattern breaks down. Given anticipated strength of
upstream ridging, wouldn`t be surprised if any significant relief is
delayed until at least Thursday. Again, low level streamline wind
analysis shows at least a partial connection to subtropical moisture
plume, supporting elevated dewpoints into the 60s. This will not
only force apparent temperatures to at or above actual temperatures,
but will not allow significant cooling during the overnight hours...
with lows likely not falling out of the 70s for some areas. While
specific heat headline criteria may not be met, no doubt early next
week continues to look uncomfortably warm at least, and perhaps
dangerously so for those who work outdoors and for those who do not
have access to home cooling.

Pattern recognition continues to support primary area of renewed
convective development remaining off to our west and northwest
through Tuesday where best juxtaposition of instability and deep
layer moisture convergence will reside. May see some scattered
diurnally-driven convection across our area, especially if lake
breeze convergence axes can mature. Definitely not expecting
anything widespread, with most areas likely remaining dry through
Tuesday. Questions with regards to shower and storm trends only
increase thereafter, again centered on just how fast early week
pattern can relax. Definitely could get a bit active the second half
of the week into next weekend, with some hints of a slow moving
baroclinic axis interacting with a well established moisture rich
environment across the Great Lakes. Only time will tell of course.

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 727 PM EDT Sat Jun 15 2024

Warmer and more humid air will return northward, as high
pressure departs to the east. Mid and high clouds will be
prevalent for much of the forecast. Rain chances will be highest
on Sunday at CIU, though at this point still don`t warrant more
than a VCSH. Conditions should stay VFR, with enough clouds and
a breeze to prevent fog tonight. If a TAF site sees precip on
Sunday (SHRA, perhaps a TSRA), then restrictions enter the
picture.

Se winds increase slowly tonight, becoming south and gustier on
Sunday. LLWS early Sunday morning at MBL.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory from noon to 11 PM EDT Sunday for LHZ348.
     Small Craft Advisory from noon Sunday to 2 AM EDT Monday for
     LHZ349.
     Small Craft Advisory from 8 AM to 10 PM EDT Sunday for LMZ323-
     341-342.
     Small Craft Advisory from 8 AM Sunday to 2 AM EDT Monday for
     LMZ344>346.

&&

$$

UPDATE...JZ
SHORT TERM...FEF
LONG TERM...MSB
AVIATION...JZ