567
FXUS63 KAPX 150158
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
958 PM EDT Sun Jul 14 2024

.KEY MESSAGES...

- Showers and storm chances early Monday morning and afternoon

- Shower/thunderstorm chances Monday evening and Monday night. A few
strong storms will be possible, with the primary hazards of damaging
winds and locally heavy rainfall.

- Cooler, less humid weather Tuesday through the end of the
  week.

&&

.UPDATE...
Issued at 958 PM EDT Sun Jul 14 2024

Typical summertime pattern in place...broad ridging and largely
capped environment across the central US with hot and humid weather
through the Midwest filtering NE-ward on return flow to aid in
convective development along the perimeter of the ridge,
particularly when aided by various small perturbations in the upper
flow. One of these perturbations is to our north, scraping Lake
Superior, though better defined vort max is yet just upstream. Cold
front extends down from the former perturbation over central
Ontario...with additional energy over MN/WI leading to a surface low
over IA...and convection developing over southern WI/northern IL.
The Lake Superior niblet, combined with some afternoon lake breeze
generation and a bit of weak surface troughing, has allowed for
convective activity over the UP through this evening...though this
is slowly starting to drift south/southeastward as of 0z.

Primary concern for the evening will be monitoring the upstream
convection, both to our north and southwest. Environment over
northern Lower this evening, per 0z sounding, still appears
favorably unstable (at least till we lose diurnal heating)...though
do think incoming convection will have to contend with the marine
boundary layer, which we`ll start to see shortly as it approaches
the northern end of Green Bay...though if it holds together and
stays on course...it`d reach northern Lower`s shores sometime around
midnight. Beyond this...will assess fog potential for tonight,
given the abundant moisture around (esp in the form of low-level
moisture over the UP where it`s been raining today) as well as weak
flow overall...and potential for convective complex over southern WI
to try to hold together across the lake tonight into the
morning.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 306 PM EDT Sun Jul 14 2024

Pattern Synopsis and Forecast:
A stronger upper level ridge remains anchored over the central
Rockies through the short term period. West winds aloft will set
up over the north side of the ridge and reach into the Great
Lakes region. Surface observations depict a wet and warm air
mass has settled in over MI with surface dewpoints in the high
60s and even some sites in the low 70s. Paired with temperatuers
in the low 80s, heat indices are reaching into the mid to high
80s and low 90s for a few sites. Skies do have some bubbling CU
around, with even some higher clouds moving overhead, however
surface temperatures are still able to warm. A lake breeze
boundary is currently forming over the eastern U.P. and will aid
in storm chances later this afternoon and evening. A favorable
environment does exist for isolated to scattered discrete
convection along any boundary that can help it initiate this
afternoon into late evening. Isolated storm chances will linger
overnight over northern lower as a stronger complex of storms
will likely move over south/central MI. Patchy fog and haze
could be seen along the northern Lk Michigan coast early Monday
morning, however skies should clear throughout the mid morning
hours. More chances for isolated storms Monday afternoon as
temperatuers warm in a humid airmass. Heat indices could reach
into the low to mid 90s for northern lower in the afternoon
hours.


Primary Forecast Concerns/Key Messages:
Uncertainty is high with Monday`s forecast for thunderstorms.
Exactly when and where storms will occur is up for debate as it
is highly dependent on convection upstream over WI/MN.
Reflection of this high uncertainty can be seen in CAMs, which
output different footprints of storms at different times almost
each run. What we do know, is that the environment is capable of
producing storms that can organize and dump heavy rainfall as
well as some gusty outflow/downburst winds tonight into Monday
afternoon. Chances for these hazards to be severe increase as we
move into Monday afternoon. At this time, the most likely
scenario is that an MCS will form over SE WI later this
afternoon and reaching SW MI overnight. Remnant moisture and
local boundary interactions could help a few storms near M-55
early Monday morning with hazards likely remaining sub-severe.
With skies clearing Monday morning, storms will be possible
along the Lk breeze boundaries however chances are low. The
complex of storms moving to our south could stabilize the air
upstream, resulting in temperatures near the surface slightly
cooler and more dry that the forecast. This would lead to less
chances for afternoon showers and storms Monday afternoon.

&&

.LONG TERM /MONDAY NIGHT THROUGH SUNDAY/...
Issued at 306 PM EDT Sun Jul 14 2024

Pattern Synopsis:
Longwave troughing looks to pivot over the upper Midwest and Great
Lakes through the majority of the upcoming work week. A shortwave
rotating around the base of said troughing will punch over the Great
Lakes Monday night, providing favorable support aloft for a surface
cyclone that is expected to trek across the northern Great Lakes
into Quebec Monday night into Tuesday, sweeping an attendant cold
front across the region during that timeframe. Surface high pressure
then looks to build across much of the north-central CONUS through
the second half of the week as expansive ridging folds eastward
across the continent.

Forecast Details:
Showers/storm chances Monday evening/night -- Relatively high
uncertainty remains in the evolution of shower/storm chances across
northern Michigan beginning Monday evening as much depends on
potential multiple rounds of convection further upstream tonight and
Monday -- specifically the potential for a severe MCS to track
across parts of the Midwest on the other side of Lake Michigan in
the Monday afternoon/evening timeframe. Current confidence is that
any potential MCS to our west/southwest will still leave a window
for convective initiation along the cold front towards the start of
the period. Even greater uncertainty lies in the southwestern extent
of convective initiation along the cold front, but the best chances
for showers and storms Monday evening into Monday night appear to be
across the eastern U.P. and Tip of the Mitt -- further away from the
negative influence of the potential MCS and in closer proximity
favorable upper-level support from the shortwave and low-level
forcing near the cyclone center.

The primary hazards with any strong storms Monday evening into
Monday night will be damaging winds and locally heavy rainfall.
MUCAPE around 1,000 J/kg and deep-layer shear near 40 kts in place
ahead of the boundary will support organized storms, and an expected
quick evolution to a linear storm mode would make damaging winds
more likely. Hail will also be possible, but chances for severe hail
are limited due to aforementioned storm mode and relatively warm
temperatures/meager lapse rates aloft creating less favorable
buoyancy through the hail growth layer. PWATs around 1.6-1.8" in
place will also support efficient rain processes, bringing the
potential for torrential rainfall underneath any strong storms that
may lead to localized ponding on roadways and briefly impact driving
conditions.

Cooler, less humid weather ahead -- After the cold front swings
across the state Monday night, cooler temperatures and less humid
air will follow behind through the rest of the work week. Highs
primarily in the 70s are anticipated Tuesday through Friday. While a
few showers may linger near Saginaw Bay Tuesday, the next main
chances for rain and potentially a few storms will be on Wednesday.
Otherwise, the second half of the week is currently expected to stay
rain-free as high pressure builds into the Great Lakes.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 740 PM EDT Sun Jul 14 2024

Storms over central UP slowly drifting ESE this evening; could
bring VCSH/TS to CIU/PLN/TVC in particular...have VCSH in tafs for
now. Think these could make it into MBL late...closer to 7-9z. Fog
to develop overnight...with IFR cigs expected at most sites and
perhaps down to LIFR at times (explicitly in CIU tafs given greatest
confidence attm). Improvements expected toward 10-14z, but not
impossible additional showers/storms pop in the morning. May need to
watch for a round of showers/storms to scrape MBL/TVC/APN toward
morning...though not clear attm...but would expect reduced visbys
with heavier rains if this occurs. Better chance of afternoon
showers/storms in the afternoon, esp at KAPN and KCIU...with
increasing southwesterly flow at most sites. Watching for another
round of storms to move in late in the TAF period and/or likely
beyond this TAF period ahead of a cold front...but have not yet
explicitly alluded to this in the TAFs.

&&

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

&&

$$

UPDATE...FEF
SHORT TERM...ELD
LONG TERM...DJC
AVIATION...FEF