785
FXUS63 KAPX 181233
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
833 AM EDT Sat May 18 2024

.KEY MESSAGES...

- Warm today.

- Chance of showers and embedded thunderstorms tonight into
  Sunday.

- Additional chances for showers and storms Monday through
  Wednesday with the potential for stronger storms Tuesday
  night.

&&

.UPDATE...
Issued at 833 AM EDT Sat May 18 2024

Fog/stratus is eroding in the interior, but near Lk Huron is
going to considerably more stubborn. Have extended the dense fog
advisory for the coastal counties until 11 am. Also added
eastern Mack Co to this, given poor conditions on webcams in the
Straits area. Inland counties still expire at 9.

&&

.SHORT TERM /THROUGH TODAY/...
Issued at 232 AM EDT Sat May 18 2024


Pattern Synopsis/Forecast: Broad warm southerly flow anticipated
today in advance of low pressure currently centered over southern
Manitoba. This low treks northeast to south of Hudson Bay by
this evening with a cold front set to cross northern Michigan
northwest to southeast tonight into early Sunday morning.

Forecast Details: Late night/early morning stratus and locally
dense fog continues to expand across eastern upper and
northeast lower. This should be fairly quick to burn off in most
spots this morning, but may linger towards midday in eastern
Chippewa/Mackinac counties. Otherwise, lots of sunshine and warm
temperatures with high temps away from the Great Lakes in the
low-mid 80s. Perhaps even a few upper 80s in southwesterly
downsloping locations. Mainly 70s at the coasts and in the
eastern U.P.

&&

.LONG TERM /TONIGHT THROUGH FRIDAY/...
Issued at 232 AM EDT Sat May 18 2024

Pattern Synopsis / Forecast: Sporadic unsettled conditions will
litter the forecast to close out the weekend as a shortwave races
through the upper Great Lakes, leading to a cold front passing
through northern Michigan Saturday night into Sunday. This front
will become more "strung out" as flow more parallel to the boundary
stunts the south and eastward advance of the front. Nonetheless,
expectation is that enough instability will be present to force some
showers and perhaps some thunder later Saturday night.
Aforementioned front looks to more or less stall / wash out farther
downstate, leaving a pool of low level moisture closer to Saginaw
Bay that could drum up additional showers and storms in that area on
Sunday. Weather next week will be dictated by an ejecting / digging
shortwave trough into the central Plains, and associated surface
cyclogenesis. There is potential for this system to track into the
upper Midwest as a deepening surface low, which, would conceptually
draw in rich Gulf moisture on Tuesday, and with the passage of any
associated frontal boundaries, presents an additional chance for
showers and storms, but there is much uncertainty to be had with the
evolution of this potential system. As far as temperatures go, looks
like abundant southwest flow aloft will keep things Summer-like into
the beginning of next week before a cooler surge of air is set to
intrude behind the early week system as we progress past midweek.

Primary Forecast Concerns:

Saturday Night Unsettled-ness: Big show (at least in the Great
Lakes) will be across Wisconsin / Western Yoop along the approaching
frontal boundary, as a pronounced area of thunderstorms (some
severe) erupt during peak heating. As this front approaches, it will
be losing steam from a forcing standpoint. Couple in with a more
nocturnal passage of the front, this doesn`t exactly spell an overly
robust outburst of convective development. CAMs seem to point toward
some semblance of elevated instability (250-500 J/kg MUCAPE), which
would support some shower and perhaps thunder development late
Saturday night (maybe into early Sunday morning)... highest PoPs in
the eastern Yoop owing to better forcing proximity, best chances
across northern lower favor north and west of an HTL to APN line.
Quite the mild night as well... expecting lows in the mid 50s to
lower 60s across the board, wouldn`t be shocked to see some spots
struggle to get much below 65 if more widespread showers do not
materialize.

Sunday: Signal for a lack of moisture scouring out in the vicinity
of Saginaw Bay remains during this forecast cycle. Owing to strong
differential heating between the land and colder Great Lakes (highs
in the 70s and 80s over land, water temps in the 40s) suggests lake
breezes will not hesitate to get going Sunday. Couple this with a
light WNW to NW wind, convergence zone will be maximized along
Saginaw Bay. With the development of ~500J/kg of CAPE, should be
enough to initiate some showers and thunder south and east of an HTL
to APN line. Will maintain PoPs from previous forecaster in that
area.

Monday - Tuesday: Digging trough into the Plains will drum up deep
moisture return into the Ohio Valley, surging into the Great Lakes
with time as well. Focus for this will be south of the dilapidated
stationary frontal boundary, which, with the advent of more
southerly flow, should be enough to force the front back northward
into the upper Great Lakes region through Monday. Progressive WSW to
ENE 500mb flow will allow for convectively charged waves to ride the
front... guidance seems honed in on a particular wave Monday evening
into early Tuesday, which could present the next shot at showers and
storms. Attention then turns to a potential surface low passing into
the vicinity of western Lake Superior... a noted climatological
signal for severe potential across the APX footprint. As guidance
stands for now, another nocturnal cold frontal passage looks to be
in the cards, but with much better forcing this time around. Still a
setup to watch for severe weather across the region, but overall,
the better potential for severe (at least more widespread / higher
end activity) favors the WI/IL/IA owing to instability coinciding
with peak heating. Nonetheless, with as much forcing as guidance is
spitting at me via the computer screen, the scenario presented of a
linear convective mode surging into portions of the CWA remains a
possibility at this juncture. Following the passage of this cold
front, more seasonable air is set to build in midweek and beyond,
with highs falling from the 70s and 80s to the 50s and 60s after
midweek.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 600 AM EDT Sat May 18 2024

Early morning dense fog at CIU/APN should burn off fairly quickly
with VFR conditions prevailing through the remainder of the day. A
broken line of showers and embedded thunderstorms may approach CIU
and the northwest lower MI terminals near or just after midnight,
although latest trends support primarily continued VFR. Winds out of
the south today with afternoon lake breeze development.

&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...Dense Fog Advisory until 11 AM EDT this morning for MIZ018-024-
     030-036-087-088-096-097.
     Dense Fog Advisory until 9 AM EDT this morning for MIZ022-023-
     028-029-034-035-042.
MARINE...None.

&&

$$

UPDATE...JZ
SHORT TERM...MJG
LONG TERM...HAD
AVIATION...MJG