071
FXUS63 KAPX 130735 CCA
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
335 AM EDT Sat Jul 13 2024

.KEY MESSAGES...

- Warm and humid with shower and thunderstorm chances Sunday
  through Tuesday.

- Trending drier, cooler, and less humid Tuesday night and
  beyond.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 331 AM EDT Sat Jul 13 2024

Pattern/synopsis: Surface ridging is trying to hold on across
central and southern lower MI. Abundant return flow is in place
to the west; 70f dew point air is as far north as Winnipeg. A
cold front will advance across the Dakotas and into MN thru
tonight. Aloft, there are weak impulses in the nearly zonal flow
over the n central US; the more prominent waves will be
generated by MCSs.

Forecast: Weak synoptic sw-erly low level flow develops today,
as surface ridging downstate gradually weakens. That flow
increases tonight, and especially overnight, when theta-e
advection ramps up locally. 900-850mb sw winds over northern
Lake MI increase to 25-30kt after 06Z.

For today, still light surface winds will allow lake breezes to
develop (once early morning fog/stratus erodes). Surface dew
points are a little lower early this morning (mid-upper 50s in
parts of northern lower MI). This will hold thru the day today.
Between that and the loss of the upper trof that was in place
the past couple of days, and deeper instability will be largely
lacking today. However, Lake MI will contribute a touch of
moisture in upper MI, and once you get away from Lake MI/Huron
more substantial heating will be realized. 500j/kg of MlCape is
possible over central and northern Chippewa Co. A developing Lk
Superior breeze will be the primary forcing mechanism. Have
expanded slightly the pops that were previously in place here,
from early afternoon into early evening. Elsewhere, mostly sunny
(once morning fog/stratus is mixed out).

Tonight, have a bit of a lull mid-evening, before return flow
steadily ramps up. A stray cell or two could be possible in
advance of any MCS from the west, and will have a small chance
for a storm near Manistee as soon as midnight. Better pops will
await more organized clusters of convection trying to push
east, along with stronger/richer return flow. Best MuCape (above
1k j/kg) is going to remain a little south of our latitude late
tonight, centered on the south half of Lake MI. Though an
organized MCS is likely to track across WI late tonight, an
expected ese-ward movement will mainly target central Lake MI
and sw lower MI by Sunday morning. Will mention a few strong
storms possible very late tonight in our far sw. Chance pops
expand across most of northern MI after 2 am tonight, but hard
to go with likely pops anywhere yet. The highest pops will
occur after 12Z.

Max temps today well into the 80s, though a bit cooler near Lake
MI. Muggy lows tonight in the 60s.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 331 AM EDT Sat Jul 13 2024

Pattern Synopsis / Forecast:

Two dominant features will work together to create a corridor of
speedy zonal flow out of the WNW, aimed directly at northern
Michigan. The first will be an absolute unit of a ridge / upper
level high over the western CONUS (currently driving record
dismantling heat in the desert SW... Las Vegas has been 115+ for 7
days). The other feature will be well to our north: a deep longwave
trough anchored over far northern Manitoba and Saskatchewan. This
classic flow regime will be accompanied by deep Gulf moisture
return... as pointed out by previous forecaster, Gulf plume has made
the long journey into North Dakota, and with this current pattern,
should easily be able to leak dewpoints well into the 60s and even
perhaps low 70s into northern Michigan through the weekend and into
next week... accompanied by temperatures well into the 80s and
perhaps breaching 90 in places barring any convection suppressing
warming in the morning hours. Given expected fire brigade of
shortwaves / embedded height disruptions passing through zonal flow,
it sure looks like a quality "MCS Mania" setup from Montana to the
Great Lakes, and pending the exact trajectory / evolution of these
convectively charged waves, could have implications on northern
Michigan as early as late tonight into Sunday. Most pronounced wave
looks to pass Monday night into Tuesday, with accompanying surface
low pressure deepening while passing through Lake Superior as the
aforementioned longwave digs southward through Ontario. This will
result in a much more refreshing airmass after Tuesday, with highs
returning into the 70s and nighttime lows ranging from near 50 to
the upper 50s to close out the work week.

Primary Forecast Concerns:

Sunday: Admittedly a frustrating amount of uncertainty with the
evolution of storms at this juncture. Following passage of morning
line of storms (see Short Term for Sat. night details), looks like
diurnal instability could make a return as partial clearing allows
for sfc temps to build back into the 80s with a newfound surge of
dewpoints, generally ranging from 65 - 73. This should drive MLCAPE
values back up to 700-1,500 Joules, and thus should be enough to
drive some returning showers and thunder. given lack of deeper
forcing overhead, pattern recognition says initiation probably get
limited to lake breezes, which, with a general WSW flow regime,
should target the eastern Yoop and NE lower. Will have to watch for
some of these storms to pack a punch... unidirectional WNW shear
profile with an ESE storm motion suggests that these storms may have
some streamwise vorticity to tap into, and thus could pose a
damaging wind / hail threat. Certainly a tricky forecast, as morning
convective activity could just slap a cloud deck over the region,
leaving us in a proverbial sweat box of 70s air temps and dewpoints
with little to no instability, and thus making me look like an
absolute walnut for even mentioning returning convection Sunday
afternoon. Safe to say that more concise updates will be had in the
coming forecast cycles.

Monday night - Tuesday: More pronounced wave and associated
deepening low pressure progged to pass through Lake Superior Monday
night into Tuesday, dragging a cold front through northern Michigan
some time between later Monday night and Tuesday afternoon. Much
like Sunday, uncertainties in timing and convective evolution cast
instability into the forecast, but most guidance seems on board with
this disturbance passing through. Conceptually, this brings more
showers and thunder to the region given the presence of deeper
moisture and better forcing. In the wake of this activity, cold air
advection set to commence as stout troughing digs into the Great
Lakes from Canada, with surface high pressure likely scouring out
lingering moisture. This should lead to a stretch of pleasant
temperatures by midweek and into the end of the week, with dry
conditions accompanying the cooldown as well.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1149 PM EDT Fri Jul 12 2024

Shallow fog potential the concern for the overnight...KMBL
already hinting at reduced visibilities. May be enough of a
breeze at KCIU to prevent any issues...always a question at
KPLN/KMBL given cold air draining and propensity to see some
fog. Should not be a long-lived issue...with VFR conditions
expected Saturday...perhaps with some convection north of KCIU.

&&

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

&&

$$

SHORT TERM...JZ
LONG TERM...HAD
AVIATION...JPB