565
FXUS63 KAPX 041759
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
159 PM EDT Sat May 4 2024

.KEY MESSAGES...

- Showers and a few thunderstorms likely tonight.

- Thunderstorm potential Tuesday and Wednesday.

&&

.UPDATE...
Issued at 1207 PM EDT Sat May 4 2024

Low cloud/fog across the southeast half of the CWA continues to
erode as daytime heating intensifies, which should warm these areas
quickly over the next few hours. Other areas are already heating up
fast, with some locations near the Lake Michigan shoreline already
climbing into the low 70s before noon. Have raised high temperatures
even further from the vast majority of guidance as models struggle
with these efficient mixing scenarios. Many areas along and west of
I-75 are expected to warm into the mid to upper 70s -- and
potentially even low 80s for some localized areas near the lakeshore
where downsloping southeast winds mix low-level profiles the most.
Otherwise, a few showers will be possible near Saginaw Bay this
afternoon before better shower and isolated thunderstorms return
this evening.

&&

.SHORT TERM /THROUGH TONIGHT/...
Synopsis/pattern: A skinny ridge of high pressure extends into
the area from the ene. Low pressure system are over far northern
Ontario, and over KS. The KS low will track ne across upper MI
and Lk Superior tonight, sending another cold front across the
area.

Forecast: Fog/status has been expanding early this morning. Fog
is most extensive over Lk Huron, into parts of central lower MI.
Dense fog has been at times in obs from APN/OSC/HTL/W Branch.
Will be entertaining a dense fog advisory in that area later
this morning.

Persistent synoptic e to se surface winds will aid in making
these clouds slow to erode, especially close to the coast.
Strong early May sun will do a number further inland...at least
mixing into a stratocu deck. Meanwhile, mid-high clouds ahead of
our next system will gradually encroach on western sections
from midday thru the afternoon. A general increasing cloud is
progged this afternoon and evening. And not only from the
west...a slug of deeper moisture will get drawn northward into
the eastern lakes, scraping by eastern lower MI. Parts of se
lower MI (including the Thumb) could see a few showers pop, but
we are slightly displaced from this better moisture thru 8 pm.
Perhaps, toward early evening, some initial showers from the KS
system could reach far western Mack Co.

Max temps toward the high end of guidance, mainly 70s, with 60s
near Lake Huron.

Cold front gradually crosses the area tonight. Best precip
chances for this event look to slightly lag this boundary, while
best instability (MuCape 300-500j/kg) is directly on the front.
The highest pops (likely showers and a slight chance for
thunder) will progress w to e across the area tonight
(especially from late evening on). Moisture availability is not
ideal, and QPF is progged at around or less than 0.25" across
the area. Though we do have some shear around, instability this
far north does not appear conducive to a svr threat from
elevated convection tonight.

Min temps lower 40s to lower 50s.

&&

.LONG TERM /SUNDAY THROUGH SATURDAY/...
PATTERN SYNOPSIS/FORECAST:

It was a period of atmospheric upheaval over the Plains...as
convection fired along a dryline in the warm sector of a southern
stream system over the southern Plains. Low-amplitude longwave
troughing across the northern Plains, with some increase in
warm/moist advection into the Upper Midwest ahead of this. Here in
the Great Lakes...high pressure briefly taking over parts of the
area, especially northern MI, in the wake of a system that brought
early-day rain to the region...and lingering low-level moisture
causing reduced visibilities across NE Lower. Upstream...another
potent trough approaches the Pacific NW.

This latter trough looks to set the tone for next week...as it plows
into the central US this weekend into early next week. Brief ridging
ahead of this Sunday into Monday, with pleasant weather to start the
week, will give way to this shortwave trough lifting across the
central CONUS as we go into Tuesday. All eyes are on this feature
for a period of active weather through at least midweek...as it
drags a warm front northward into the Great Lakes going into Tuesday
night or so. A second wave of energy slipping through lingering
longwave troughing over the Plains should keep the activity going
into the latter half of next week. Signals currently point toward
troughing hanging over the region into late next week, and perhaps
beyond....with some potential for cooler weather (at least "normal",
if not even slightly below) to be the norm for a change going to mid-
month...just when we don`t want it.

Primary Forecast Concerns:

Thunderstorm potential Tuesday/Wednesday...Still way too early to
nail down the major details...but setup is definitely supportive of
activity for Tuesday into Wednesday... as current signals for
negatively tilted trough axis to lift across the Upper Midwest
during this timeframe have piqued at least my interest, and
certainly the interest of convection fanatics, as these tend to be
more dynamic systems with more oomph. Additionally...this idea could
lead to an occluding surface low along a warm front in our vicinity,
which could further complicate/enhance potential thunderstorm
hazards with this system. Some potential for anomalous deep moisture
along said warm front as well, which bears watching as well, for
hydrology purposes, depending on how dry we are ahead of the front.
All this being said...not impossible that the better ingredients for
severe weather may end up remaining to our south/southwest, as
usual, particularly if the warm front stalls over us/low occludes in
our region...in which case it may be more likely we`ll be in
stratiform rain with embedded thunder...which, for what it`s worth,
could also lean a little toward a locally heavy rain threat. Bottom
line...keep an eye on the forecast for Tuesday/Wednesday next week.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...

IFR/MVFR CIGs are expected to continue at APN through this afternoon
and tonight as southeast winds keep low stratus/BR/FG in place, and
will eventually rise to VFR later Sunday morning. Otherwise, VFR
conditions are anticipated at other northern Michigan TAF sites
through the early evening hours. MVFR/IFR CIGs are expected to move
in late this evening and overnight, accompanying chances for rain
showers into Sunday morning. VFR conditions are anticipated across
all TAF sites by early Sunday afternoon.

&&

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

&&

$$

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