613
FXUS63 KAPX 101945
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
345 PM EDT Wed Jul 10 2024

.KEY MESSAGES...

- Showers and embedded thunderstorms through this afternoon;
  locally heavy rain possible...

- More afternoon showers Thursday...

- Warmer and more humid this weekend into early next week with
  occasional shower/storm chances.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 343 PM EDT Wed Jul 10 2024

PATTERN SYNOPSIS/FORECAST:

Earlier punch of PV now well to our northeast...with 1000mb surface
low starting to slip into Canada north of Lake Erie. Deformation
axis overhead, and band of rain over the Sunrise Coast associated
with this, though beginning to fade as better moisture and forcing
pull away. Weak NE low-level flow over NW Lower...with diurnal
heating...allowing for development of Lake Michigan lake breeze,
allowing for enhancement of low-level convergence largely along the
US-131 corridor from Indian River down toward CAD...though a few
showers also popping up over the EUP. (Given NE low-level flow...pop-
ups are moving very little if at all...and if moving, are moving to
the SW.) Much more clearing upstream over WI...between us...and the
next niblet spinning over IA/MN...as PV strand pushes southward over
Lake Superior.

Overall trough axis should remain over us through the night; we
should start to see a bit of shortwave ridging as the upstream
trough axis digs into IL...though PV strand draped across Lake
Superior certainly has potential to shove its way down into northern
Lower toward morning. Expecting pop-ups to continue through the
afternoon, with an uptick toward early evening...and then things
should start to quiet down for the night...as remaining synoptic
moisture slips eastward. Nebulous flow tonight with some potential
for fog...followed by increasing chances for pop-up showers again
during the day Thursday ahead of both the positively tilted trough
axis aloft...as well as diurnal heating and lake breeze action, this
time across the northeastern side of the CWA. Temps/dewpoints likely
to remain similar to today...though there is some potential for
slightly lower humidity to slip in behind that shortwave trough
axis.

Primary Forecast Concerns:

Showers/embedded thunder and heavy rain potential this
afternoon/evening... Some breaks in the clouds this morning/early
afternoon have allowed decent diurnal heating to bubble up lower-
based cu. Atmosphere did already have a bit of energy (per morning
sounding`s approx. 100j/kg MUCape)...and the additional surface
heating only helping the cause as trough axis and cooler air aloft
tries to move in overhead, supportive of an additional (minor) boost
to instability this afternoon. Do think lightning and perhaps small
hail/gusty winds could be a concern with any of the more robust
storms...but for now, not expecting anything overly impressive on
storm intensity.

Rain intensity, on the other hand, could be a bit more robust
yet...given that deep moisture hasn`t yet fully departed (pwats
still 1.2-1.3in. over the area)...and freezing levels remain up
around 3km or better...further supportive of efficient warm-rain
processes in this tropical-type environment. Thermal/stability
profiles also support more efficient rain processes...so won`t be
impossible for some areas to get dumped on pretty good through this
evening under these more convective rains...especially if they
manage to hang over an area for any length of time. Current QPF
forecast is 0.15-0.50in. under this convective stuff...certainly not
impossible that some areas could see closer to an inch or better
through this evening if cells persist, esp down toward Kalkaska-ish
or so. More stratiform/synoptic-type rains over NE Lower appear to
be waning overall, per radar trends...and will expect this idea to
continue into this evening.

With the trough axis and core of coldest air aloft again sliding in
from the northwest through the day Thursday...think there will be
another good shot at afternoon pop-up showers and storms, especially
across northeast Lower. Moisture not expected to be as plentiful, so
not expecting quite as much in the way of rainfall, even from the
convective stuff that pops up...though not impossible it could put
down another half inch at best.

&&

.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
Issued at 343 PM EDT Wed Jul 10 2024

Pattern Forecast: Mid-upper level trough axis is expected to be
positioned just upstream/nearly overhead by Thursday evening before
gradually shifting off to the northeast through early-midday Friday.
Heights build Friday afternoon through early next week aiding to
bring warmer and more humid conditions to much of northern Michigan.
That said, occasional mid-level shortwaves are progged to ripple
through the flow at times with at least isolated to scattered
shower/storm chances from time to time. Latest longer range trends
support a cold front crossing the northern Great Lakes during the
Tuesday/Tuesday night time frame -- eventually delivering a return
to cooler temperatures toward the middle of next week.

Forecast Details: Early Thursday evening, perhaps a diurnally driven
rogue shower/storm lingers primarily over northern lower through
sunset. Otherwise, generally tranquil conditions anticipated
Thursday night through much of Friday with highs Friday afternoon
back into the 80s area-wide. Diurnally driven instability does build
again during the day Friday with ~500 J/kg MUCAPE anticipated by mid-
afternoon. Limited upper support for much shower/storm activity, but
enough low-level lake breeze convergence to include at least low
pops -- particularly over northeast lower.

Heat/humidity build for Saturday - Monday with highs through the 80s
to near 90 degrees for some. Dew points generally in the mid-60s
Saturday rising to near 70 degrees on Sunday/Monday...certainly
providing a more sticky mid-summer feel. Once again, likely enough
instability to warrant shower/storm chances from time to time,
perhaps with the greatest chances late Saturday night/Sunday given
some increased support from a series of mid-level waves progged to
slide overhead. Even some upstream MCS potential through this late
weekend time frame that`ll be worth keeping an eye on.

Longer ranged guidance in fairly good agreement that a cold front
approaches and eventually crosses northern MI somewhere in the
Tuesday/Tuesday night time frame. While inherent uncertainty exists
given day 6-7, this would support additional shower/storm chances
and a return to cooler (even somewhat below normal) temperatures by
the middle of next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 129 PM EDT Wed Jul 10 2024

Expecting more pop-up showers/storms to develop from EUP down toward
MBL this afternoon...between 18z and 3z. (Lake breeze noted along
the US-131 corridor from KGRR to KTVC...will monitor this region for
development that could impact TVC/MBL taf sites.) Slow-moving cells
likely to move from NE to SW given N/NE low-level flow...if they
move much at all. (Winds above 2000-3000ft from the NW, 15-25kts.)
Rain to hang out over KAPN most of the afternoon/evening...and could
hang out longer into the night. Not impossible for some sites (such
as KAPN) to go IFR at times this afternoon with a few sub-1kft cloud
bases over that way...but primarily expecting MVFR to VFR conditions
otherwise this afternoon for the area. Watching fog/low-cigs
potential for tonight as winds go light, esp at APN, MBL where most
rain is likely to fall...with IFR likely and LIFR possible.
Currently expecting improvements through the morning Thursday.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 8 AM EDT Thursday for LHZ349.

&&

$$

SHORT TERM...FEF
LONG TERM...MJG
AVIATION...FEF