529
FXUS63 KAPX 140632
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
232 AM EDT Wed Aug 14 2024

.KEY MESSAGES...

- Potential for storms with heavy rain Thursday into Friday

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 232 AM EDT Wed Aug 14 2024

...Continued warm and dry today...

High Impact Weather Potential...None.

Large area of strong high pressure remains parked over most of the
eastern half of the US early this morning...centered squarely over
Michigan. Clear skies and light/calm winds are again lending to some
patchy late night/early morning fog development across portions of
our CWA...as temps cool into the 50s.

High pressure center will gradually shift east of our state over the
next 24 hours. Strong subsidence and dry air thru the column will
continue to dominate our wx...lending to continued clear skies and
warm mid August temps.

Persistent light wind regime will again allow for lake breeze
development this afternoon. High temps this afternoon will warm into
the low to mid 80s...with overnight lows cooling into the upper 50s
and lower 60s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 232 AM EDT Wed Aug 14 2024

PATTERN SYNOPSIS/FORECAST:

Anomalous ridge centered over northern Canada/Hudson Bay. Ridge axis
building across the central US toward the Great Lakes. General N-S
line of troughing marching across the western US...though northern
stream segment over Alberta is a bit ahead of the troughing over the
Rockies. Ridge center over the Mid MS Valley with an upper trough
over northern Mexico resulting in good return flow off the Gulf into
the Lee of the Rockies, where the bulk of the convective activity is
located as of 4-5z...along a BCZ generally stretching from Alberta
down into the Lower MS Valley and Gulf Coast. Warm advection into
the Upper Midwest...though upper flow is still northwesterly into
the Great Lakes/Northern Michigan...with a little bit of moisture
advection into the region attm. (Nowhere near as good of moisture as
upstream, though.)

Expecting ridge axis to move overhead today, with upstream troughing
quickly shoving its way into the Upper Midwest going into Thursday.
Ahead of this...expecting warm advection precipitation to develop
over WI into parts of MI ahead of the primary surface low for
Thursday. Better shot at widespread precipitation looks to be
Thursday night...with the trough axis and upper jet more favorably
poised over the region. Attendant surface low to slowly meander
across northern Michigan Friday into Saturday, finally departing
eastward going into Saturday night/Sunday...with a longer-duration
rain and embedded thunderstorms to contend with in the meantime.
Beyond this...some uncertainty in how quickly broader troughing
departs the region...as the pattern begins to turn blocky, with
ridge axis over the central US going into the weekend and beyond.
Think some of this uncertainty will be related to how T.C. Ernesto
ends up getting absorbed into the flow later this week. Additional
uncertainty lies in how far south additional northern stream niblets
are able to get to reinforce the troughing over our region for early
next week. While there is at least some minor potential for a bit of
unsettled activity early next week, think the primary difference
will be how cool we remain, particularly if we end up with Canadian
high pressure overhead (or not).


Primary Forecast Concerns:

Heavy rain potential Thursday into Friday...do have concerns with
the anomalous moisture plume in the vicinity (likely overhead)
combined with more synoptic forcing for a change with that trough
and attendant surface low. This being said...think there is still a
good chance the heaviest rainfall ends up being to our southwest
Thursday afternoon/evening where the environment should be a little
more favorable....though we should still see some warm advection
activity, especially over our SW CWA toward TC, Manistee, Cadillac,
as it slowly lifts northeastward through the night. Do have some
concerns with the LLJ becoming a little more parallel to the
boundary Thursday afternoon, with respect to training potential...so
will have to keep an eye on this. In fact, this general idea of the
warm front being in the vicinity through the period as the surface
low likely tracks across northern Michigan suggests a concern for a
swath of steady, more synoptic rainfall (rather than straight-up
convective) to remain focused over parts of the area along and north
of the low track over a longer duration (Thursday night into at
least Friday afternoon, if not longer)...which could certainly lead
to some hydro concerns if this verifies. Attm, do have some moderate
confidence in this idea...with some probabilistic guidance
suggesting a greater than 40 percent chance for an E-W swath of at
least an inch in 24 hrs somewhere across northern MI. Guidance has
been hinting at this idea for the last couple days, though the
position of this swath has shifted from closer to the Straits last
night to closer to M-32 attm...so will have to keep an eye on this.

Storm potential Thursday into Friday...guidance derived soundings
show the presence of elevated instability, particularly Friday
morning into Friday afternoon. Even some potential that the
instability (perhaps 500-1000 J/kg CAPE?) could become surface based
over parts of the area, particularly in the warm sector, Friday
afternoon. Signals are not impressive with regard to deep layer
shear up here, which is fortunate...but certainly think we could
have some storms around through the day. Even if we never break out
of the clouds (and especially if we do break out of the clouds).

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1137 PM EDT Tue Aug 13 2024

Still looking at some patchy fog/mist developing early this
morning, especially at KMBL and KCIU. Any fog/mist should lift
quickly around sunrise, leaving behind VFR conditions under just
some passing high clouds and high based cumulus today. Light
winds with local lake breeze development again this afternoon.
Winds go light to calm again this evening.

&&

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

&&

$$

SHORT TERM...MLR
LONG TERM...FEF
AVIATION...MSB