-- Discussion containing changed information from previous version are highlighted. --
725
FXUS61 KCLE 221337
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
937 AM EDT Wed May 22 2024

.SYNOPSIS...
An occluded low pressure system over the arrowhead of Minnesota
will extend a cold front across the area today. This front will
be extremely slow to move southeast, reaching the Ohio River by
daybreak on Thursday. High pressure will nestle across the area
for Thursday. The former cold front over the Ohio River will be
lifted north as a warm front on Friday. A cold front will move
across the area on Saturday.

&&

.NEAR TERM /THROUGH THURSDAY/...

-- Changed Discussion --
Made only minor adjustments to the forecast for the afternoon.
Ongoing convection over southwest Ohio is weakening as shown by
the warming cloud top temperatures as this debris advects
northeast into the region. The showers and clouds will slow the
warming today and keep max temperatures cooler than yesterday.
There is still some uncertainty on the potential development of
more robust/severe convection this afternoon and evening
especially with the present debris clouds/showers moving into
the region. Timing of more significant convective initiation may
be after 18Z to 20Z.


Previous discussion...
Some light radar returns are showing up across
Northwest Ohio, but these largely are not making it to the
surface. Meanwhile, a complex of showers and storms is moving
along the Ohio River. Have some slight concerns that this
feature could rob some moisture away from the area and further
limit storm potential later this morning in Northwest Ohio.
Meanwhile, this complex will move northeast in some form and
could have implications for the slight risk area for the eastern
portion of the area.

Previous Discussion...
An occluding low pressure system just northeast of Duluth,
Minnesota will continue spinning northeast into Canada today, as
the main upper trough consolidates into a closed upper low over
Northwest Ontario. The occluding low has extended a cold front
well south, stretching through Southeast Wisconsin to the St.
Louis Metro and into northern Texas. Ahead of this front, a
subtle trough is moving through western Indiana, supporting the
development of some shower and thunderstorm activity. This
trough feature has the support of a mid-level vorticity maximum
advecting east across the Great Lakes and Ohio Valley regions
and will be the feature to watch today for future shower and
storm development. For Northwest Ohio, this boundary will have a
small chance at bringing some showers and storms around
daybreak, but the trend is down as the region has stabilized and
the low level jet has not be super successful in supporting new
convection. Therefore, PoP trends are down for the western third
of the area. However, still suspect this boundary to be more
successful in convective development further east as the
atmosphere is able to better destabilize this afternoon. The
other possible source for storm development today will be along
the lake/land interface in northern Ohio and NW PA, as there
could be a subtle lake boundary that will set up this afternoon
with the land/water temperature differential and become a focus
source for storms for the far eastern portions of the area.
There won`t be a bonifide lake breeze with the stronger
pressure gradient across the region to allow for a larger
boundary for storm development, but this more subtle boundary
could be enough. Finally, there is the main cold front, which is
both apart from better upper level support and will be slowing
as it enters the region. It will be present to provide one final
source of lift for convective development, but other mechanisms
may prompt new convective initiation first and this boundary is
seen more as the end of storms for the day.

The overall picture is that storms are expected to form off the
aforementioned boundaries and develop in an environment
suitable for strong to severe storm development with up to 2000
J/kg of MLCAPE and 0-6 km bulk shear of around 35 kt. Forecast
soundings across the eastern half of the area depict steep low
level lapse rates and mid-level dry air that will be favorable
for damaging wind gusts. There is enough shear to support a more
sustaining updraft and introduce some rotation for large hail
or a tornado; however, these threats appear more marginal
compared to the wind threat. The overall limiting factor for
today will be if the region remains too capped and storm
coverage ends up being low. The total aggregate of lifting
mechanisms are several subtle and mistimed features that will
not be aligned to allow for widespread, explosive convective
development. Therefore, the eastern half of the area is
delineated in a Slight Risk for severe weather for the wind
threat and the best window for anything would be Noon to 6 PM
or so for this region. For the western marginal risk, the threat
will be over quickly in the day and likely will not exist past
4 PM. The marginal areas are already starting to seem less
favorable for much to happen, given how little has happened in
Indiana overnight and the current timing of boundaries that
would be while the environment remains fairly stable.

The surface cold front will eventually work its way through the
area behind the main severe show and would generate some light
shower/storm activity, if the environment isn`t already worked
over this afternoon. This front will be the ending point for
convection and have trended the forecast drier sooner from
northwest to southeast across the area. High pressure will build
into the area behind the front and keep most of the area dry for
tonight into Thursday. The front will settle near the Ohio River
tonight and attempt to nudge north on Thursday and have some
small PoPs in the southern counties, but overall, Thursday
should be dry. Temperatures won`t have to do much to return to
the 80s today. The cold front isn`t all that strong with the air
mass change and a mix of 70s to lower 80s will be expected for
Thursday.
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
Dry weather will prevail Thursday night into at least the first half
of Friday as a ridge expands east into the region. A cold front over
the Ohio Valley will begin to lift north as a warm front throughout
the day Friday as a vertically stacked low drifts north-northeast
across the Upper Midwest. Most of the area will likely be in the
warm sector by Friday afternoon/evening and an approaching shortwave
will allow PoPs to increase from the southwest Friday afternoon and
especially Friday evening into Friday night as the low`s associated
cold front approaches from the west. Still some uncertainty in the
timing of the front and the resulting precipitation chances. The GFS
has a bit more low to mid level moisture and higher precip chances
than other deterministic guidance members Friday afternoon and
Friday evening, whereas the ECMWF, NAM, and Canadian hold off on
precipitation until the front arrives later Friday night or early
Saturday morning. The best thermodynamics will likely remain to the
south of the area and do not anticipate organized convection,
especially since the highest rain chances will occur during a
diurnally unfavorable period. PoPs will be highest in the western
half of the CWA Friday night and in eastern zones Saturday
afternoon. Dry weather should return by Saturday evening as high
pressure briefly builds over the region.

Warm air advection will result in above normal highs in the low to
mid 80s Friday with overnight lows in the low to mid 60s. Saturday
will be slightly cooler with maximum temps in the upper 70s to lower
80s and minimum temps in the mid to upper 50s.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
The dry forecast will be short-lived as the next system, likely an
upper trough with a deepening surface low, lifts northeast from the
central Plains/Mississippi Valley Sunday. The approaching system
will lift a warm front across the region Sunday before tracking into
the Great Lakes or northern Ohio Valley Sunday night into Monday.
Still a lot to iron out with the synoptic setup for this system, but
all guidance indicates a decent chance of precipitation Sunday
evening through Monday, which is reflected with chance to likely
PoPs across the area. Cyclonic flow both at the surface and aloft
may persist through Tuesday and there might even be some lake-
enhanced rain showers over the area.

Above normal temperatures (upper 70s to lower 80s) continue into
Sunday before temps cool to near normal values (low to mid 70s) for
Monday. By Tuesday, cyclonic flow/cold air advection will likely
provide slightly below normal highs in the upper 70s to lower 70s.
Overnight lows will be in the 50s and lower 60s each night.

&&

.AVIATION /12Z Wednesday THROUGH Sunday/...
VFR conditions are in place this morning with mid-level clouds
moving into the region ahead of a cold front. Some radar returns
are present in Northwest Ohio, but these aren`t making it to the
ground, let alone impacting a terminal. The cold front, along
with a complex of storms in SW Ohio will enter and help generate
additional showers and storms in the region. The main area for
additional convection would be KCLE to KMFD and east, although
confidence in a TS at a terminal is still just limited to just
KCAK, KYNG, and KERI at this time, and have a TEMPO window when
the best chance for a TS at those terminals would be this
afternoon. Additional TS is unlikely after a brief window this
afternoon and clouds will be present across the region until the
final cold frontal passage. Behind the front, skies will trend
to VFR and in many places, clear, and winds will favor a
generally westerly flow.

Outlook...Scattered showers and storms on Friday and Saturday
could also bring brief non-VFR conditions.

&&

.MARINE...
Southeast winds will increase to 10 to 20 knots by late morning or
early afternoon as a cold front approaches from the west. Showers
and thunderstorms are possible well ahead of this front this
afternoon. As of now, a Small Craft Advisory is not needed since
waves will be under 4 feet due to offshore flow. Winds diminish
below 10 knots and shift to the west/northwest behind the front
before becoming variable and remaining under 10 knots Thursday
through much of Friday. Expect flow to shift from the southeast to
southwest and increase to 10 to 15 knots as a cold front crosses the
lake Saturday before gradually backing to the east/northeast
Saturday evening into Sunday. A warm front will cause winds to shift
to the southeast Sunday evening.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...Sefcovic
NEAR TERM...LaPlante
SHORT TERM...Maines
LONG TERM...Maines
AVIATION...Sefcovic
MARINE...Maines