104
FXUS61 KCLE 080134
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
934 PM EDT Tue May 7 2024

.SYNOPSIS...
A warm front will lift north of the area this evening before a
cold front sweeps east across the region late tonight into
Wednesday morning. A series of disturbances will cross the local
area Wednesday night through the end of the week.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
930 PM Update...
Thunderstorms have entered the western CWA, although they have
quickly begun to weaken with weakened instability closer to the
warm front. A Tornado Watch remains in effect for western
counties through 3Z and an additional Tornado Watch has been
issued for additional counties in the southern portion of the
CWA until 8Z. ESRH values continue to linger near 300 m2/s2 with
shear values estimated to be near 40-60 knots. These values are
higher south of the area, resulting in the ongoing convection,
but development further north cannot confidently be ruled out at
this point. Highest confidence of strong thunderstorm
development and isolated tornadoes is along the southern CWA.
Will continue to monitor over the next few hours to see how the
atmosphere evolves given the convection south of the area.

630 PM Update...
A warm front continues to slowly move north this evening with it
currently extending east near the southern shore of Lake Erie.
The positioning of this boundary has allowed the entire CWA to
remain in the warm sector of the low this evening and in an area
of enhanced instability and high shear values. Looking upstream,
numerous discrete cells have already produced large, damaging
hail and tornadoes. These cells will continue to move east,
entering the CWA around 00Z for western counties and moving east
throughout the early overnight. Hodographs continue to suggest a
favorable environment for rotating updrafts which suggests a
continued threat of tornadoes and large hail into the area. Will
continue to monitor the mesoscale environment. The Tornado Watch
remains in effect for western counties, but have added Marion
and Morrow Counties to the watch with this update.

500 PM Update...
A Tornado Watch has been issued for the western 2 tiers of
counties that will remain in effect through 11PM EDT. Weak
showers are currently moving east across the area, but are not
acting to stabilize the atmosphere. Upstream scattered
thunderstorms will continue to strengthen and move into the
watch area around 8PM EDT. A couple tornadoes are possible,
along with damaging wind gusts up to 70 mph and large hail.

Previous Discussion...
The first round of showers and non-severe storms, associated
with a shortwave, are lifting across the local area this
afternoon. The showers and storms are already showing signs of
weakening. It`s important to note that this round of
precipitation is not the main show for severe weather today; the
main show is currently blossoming across northeastern Illinois
and northwestern Indiana which will continue moving east towards
the CWA this afternoon into the first few hours of this
evening. By 8 PM or so, the storms should be approaching or
entering the western reaches of the CWA before continuing to
track east through the CWA through about Midnight.

Overall, the severe weather threat remains unchanged and there`s
still potential for all hazards of severe weather (tornadoes, hail,
and damaging wind gusts) given the impressive wind field, effective
bulk shear values of over 60 knots, and hodographs/soundings that
support potential for strong and rotating updrafts, but there`s
still a touch of uncertainty regarding the instability and warm
air/moisture advection. Latest high resolution guidance members have
a narrow corridor of MLCAPE values of 1500 to 2000 J/kg in the
western and especially southwestern zones of the CWA (aka the area
in the Enhanced and Slight risks), but this window may be brief
which could make the difference between a severe weather risk and a
more significant severe weather risk. However, as of writing, MLCAPE
values are currently around 1000 J/kg just to the west of the CWA
with slightly higher values further southwest and expect instability
to increase over the next several hours so don`t have concerns with
the forecast at this point. Biggest area of concern for severe
weather potential will lie near the I-75 corridor, where soundings
support an environment favorable for tornadoes and large hail.
Storms should weaken as they move east across the CWA especially as
the sun goes down and diurnal instability wanes. Storms should exit
to the east near or shortly after Midnight tonight.

Generally expect dry weather for much of Wednesday before the next
wave of showers/thunderstorms lifts northeast towards the CWA by
Wednesday night.

Tonight`s lows will be in the upper 50s to lower 60s with
Wednesday`s highs climbing into the upper 70s to lower 80s on
Wednesday. Wednesday night`s lows will be in the 50s.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Upper-level trough swings southeast across the Great Lakes region on
Thursday with the associated surface low moving east across the Ohio
Valley. Rain showers are expected with isolated thunderstorms,
especially during the first half of the day. Precipitation chances
decrease through the evening/overnight hours with isolated to
scattered light rain showers lingering into the day Friday as
troughing persists on the backside of the departing low. High
pressure briefly builds in Friday night.

Temperatures in the short term period will be a bit cooler than the
previous few days as that first upper-level trough swings through,
with highs in the 60s.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Another upper-level trough and weak low move southeast across the
Great Lakes region with scattered showers and isolated afternoon
thunderstorms Saturday through Sunday (best PoPs of 50-60% on
Saturday). Uncertainty in the synoptic-scale pattern makes for a low
confidence forecast on Monday and Tuesday. Main trend is for low
chance PoPs each day and gradually warming temperatures (likely in
the 70s by Tuesday).

&&

.AVIATION /00Z Wednesday THROUGH Sunday/...
Generally widespread VFR conditions are being observed across
the area this evening other than in patchy areas of lower
ceilings resulting in isolated MVFR conditions at terminals.
Over the next couple hours, convection is expected to push east
across the area with strong to severe convection possible.
Looking upstream, discrete cell convection is nearing the OH/IN
border with some storms having a history of producing large hail
and tornadoes. With the entire area in the warm sector of the
low pressure system, conditions remain favorable for this severe
weather to continue into the area. As a result, KTOL and KFDY
remain under a Tornado Watch until 11 PM EDT. As these storms
moves east after sunset, some instability will be lost and
storms will gradually weaken, but cannot rule out isolated
stronger storms moving through the entire area. Generally
speaking, all storms should exit the area by 06Z Wednesday. With
the discrete nature of these cells it was difficult to pinpoint
the exact location of the storms and thus opted to handle storms
with a TEMPO that highlights the best timing for impacts. These
conditions include wind gusts up to 35 knots and visibilities
dropping to MVFR, possibly IFR in the heaviest showers. As the
showers taper from west to east, conditions should rebound to
VFR with the exception of KYNG and KERI which may have lingering
MVFR ceilings until sunrise Wednesday.

Winds this evening will remain out of the south-southwest at
10-14 knots, occasionally gusting up to 25 knots for western
terminals. These winds will gain a more westerly component by
Wednesday morning at 5-10 knots. Near sunset on Wednesday, winds
will become light and variable.

Outlook...Non-VFR likely with periodic showers and thunderstorms
through Sunday.

&&

.MARINE...
A warm front lifts north across Lake Erie this evening with winds
becoming southwest around 15 knots. A subsequent cold front moves
east across the region late tonight into early Wednesday morning
with westerly winds of 10-15 knots expected through the day
Wednesday. Low pressure moves east across the Ohio Valley on
Thursday with easterly to northeastly flow Thursday morning becoming
more north and northwest by Thursday night. A small craft advisory
is possible primarily for wave heights around 4 feet in the central
basin Thursday and Thursday night. A weak low moves southeast across
the Great Lakes but winds look to stay at or below 10 knots.

&&

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

&&

$$

SYNOPSIS...Maines
NEAR TERM...Campbell/Maines
SHORT TERM...Saunders
LONG TERM...Saunders
AVIATION...Campbell
MARINE...Saunders