-- Discussion containing changed information from previous version are highlighted. --
471
FXUS61 KCLE 242335
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
735 PM EDT Fri May 24 2024

.SYNOPSIS...
Low pressure over the Upper Midwest will swing a cold front east
across the region late tonight into Saturday. High pressure briefly
returns Saturday night before another low pressure system out of the
Great Plains lifts northeast into the Ohio Valley Sunday night into
Monday.

&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
-- Changed Discussion --
730 PM...A complex of sub-severe thunderstorms continues to move
east across eastern Indiana this evening, though recent
satellite cloud-top warming suggests that a weakening trend may
be imminent as it moves into a more stable environment.
Nonetheless, did increase PoPs a bit out west, particularly
along the I-75 corridor as a few isolated to scattered
thunderstorms cannot be ruled out this evening into the early
overnight.

Previous Discussion...High level clouds will begin to filter
overhead this evening ahead of a weakening line of showers and
storms moving across Indiana along a cold front. Quiet for much
of the evening and overnight with warm lows in the low to mid
60s. Expect for showers and storms to continue to decrease in
intensity and coverage as they move toward the I-75 corridor
overnight tonight and early Saturday morning. Some isolated
showers may persist Saturday morning and early afternoon before
shower coverage increases Saturday afternoon and evening along
and east of I-71. Temperatures rise into the upper 70s
accompanied by dew points in the low to mid 60s Saturday
afternoon and evening as the atmosphere destabilizes. This warm
and moist atmosphere will support MLCAPE values in the 1500-2000
J/kg range east of I-71 with roughly 20-30 knots of 0-6 km
shear. There is a Marginal Risk (Level 1/5) for severe weather
across the eastern half of our forecast area on Saturday.
Damaging wind gusts and large hail will be the primary hazards
with any strong to severe storm Saturday afternoon and evening.
The general timing for showers and storms looks to be between 2
and 8 PM.

Showers and storms exit to the east Saturday evening as a brief area
of high pressure builds overhead. Overnight lows on Saturday night
will be closer to normal as they settle in the mid 50s. An active
pattern continues into the short term period, for more information
on Sunday`s hazardous weather threat, see the below discussion.
-- End Changed Discussion --

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
Sunday will be a day that folks across the Ohio Valley and lower
Great Lakes region should stay updated and weather aware this
Memorial Day Weekend for the threat of widespread severe weather
potential, especially during the time frame of late Sunday afternoon
into the overnight hours. The day 3 outlook from SPC currently has a
marginal to slight risk area into portions of northern and
northwestern Ohio. But the trends with the forecast models, and more
so with the latest 12z guidance, is indicating that severe weather
potential and threat may be increasing as well as shifting
northeastward closer to the lower Great Lakes region for Sunday
afternoon and evening. We are now getting into that time window of
48 to 60 hours out where the CAMS and high-res short term models are
able to start seeing this weather system and narrowing done the
severe weather potential with more details and confidence. With
that said, it is looking very possible that when SPC does the
next severe weather outlook update for Sunday, there may be a
shift of those higher probabilities into northwest and north
central Ohio, including the Toledo and Cleveland metro areas.

A developing and deepening surface low pressure system will track
northeastward across the Cornbelt Region and Upper Midwest through
the western Great Lakes region on Sunday. There will be a moisture
rich and very warm airmass over the Ohio Valley and lower Great
Lakes region Sunday afternoon into the evening ahead of this
approaching cold front. Most of the day Sunday up through late
afternoon will be fairly quiet with mostly sunny skies and very warm
temps climbing into the lower to mid 80s. As for the thermodynamics
and the atmospheric parameters, that is looking a more
favorable for severe storms to develop and organized convection.
CAPE may climb to into very unstable range of 2000-3500+ J/kg
with the higher values of potential energy expected across
northwest Ohio. A low level jet of 50-60 knots will push into
the region which will aid in direction and speed wind shear. PW
values will be on the higher levels between 1.5 and 1.8 inches
that will help with a heavy rainfall threat and rainfall rates
as well with deeper convection. There is a slight excessive
rainfall threat and a limited risk for some localized heavy
rainfall amounts and flash flooding possible. Some of the severe
weather composite parameters and index with the CAMs are on the
moderate to higher side of the scale. The supercell index
parameter is in the higher range for northwest and north central
Ohio Sunday evening. And the tornado parameter (sig tor) index
has increased with the latest 12z guidance as well.

There still is some uncertainty regarding the full severe weather
threat and how this event will develop and unfold just west of our
area late Sunday. It is starting to appear that a line of intense
convection may develop along the cold front west of our area late
Sunday afternoon and push into Northwest Ohio by early to mid
Sunday evening. There will also be the threat of isolated
supercells just ahead or embedded with this line of severe
storms. All modes and severe weather threats will be possible.
Damaging wind gusts up to 70 mph or higher will be the main
threat followed by large hail up to golfball size potentially
given the strong CAPE values. There will be a tornado threat as
well, especially if we have supercells to develop and that
higher potential may be closer to northwestern Ohio. This line
of severe storms will move across northern Ohio and across Lake
Erie through the late evening. It will continue through
northwest Pennsylvania into the late night hours but also weaken
as it advances eastward across NEOH and NWPA. The cold front
and associated convection should be east of our CWA by 12z
Monday morning. We will have improving weather conditions on
Monday behind the frontal passage with slightly cooler high
temps.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
The weather pattern will remain somewhat unsettled into the middle
of next week. A large upper level trough will carve out across the
Great Lakes region by the middle of next week. A secondary cold
front will swing through on Tuesday and usher in a much cooler
airmass for the middle and end of next week. There will be off and
on scattered rain showers Tuesday through early Thursday morning
associated the upper level trough. The scattered rain showers and
isolated thunder will be mainly diurnal driven with the daytime
heating and colder air aloft. There will be periods of clouds and
sun during for the middle of the week but it will also not with
instablilty driven showers. High temps will be in the 60s to
near 70. Overnight temps will be cool in the 50s with a couple
night late next week getting down in the middle and upper 40s. A
large surface high pressure system will build down across the
Great Lakes Thursday and Friday with nicer weather and clearer
skies. Temperatures will slowly rebound upward by the end of the
week.

&&

.AVIATION /00Z Saturday THROUGH Wednesday/...
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VFR across the TAF sites this evening with mainly VFR to persist
through the TAF period outside of thunderstorms. As of this
evening, there is a cluster of thunderstorms off to our west
across eastern Indiana, though expect this activity to weaken
over the next couple of hours as it enters a less favorable
environment. Given uncertainty in strength and timing, opted for
vcts mention at FDY/TOL generally through the rest of this
evening. Otherwise, attention then turns to Saturday morning and
afternoon as another round of thunderstorms are possible, mainly
along and east of the I-71 corridor. There may be multiple
rounds of thunderstorms; one in the mid to late morning and
another in the mid to late afternoon. The highest confidence for
thunderstorms to impact TAF sites are at YNG/ERI so opted to
include a brief tempo group at both sites in this update.

Winds are quite variable this evening, out of the north 5 to 10
knots behind a lake breeze, and out of the south to southwest 5
to 10 knots behind an approaching warm front. Winds will become
southerly by Saturday morning, 5 to 10 knots, then abruptly
shift towards the west and northwest behind a cold front
Saturday afternoon and evening.

Outlook...Non-VFR possible in showers and thunderstorms Sunday
evening into Monday. Periodic Non-VFR conditions may persist in
scattered showers and thunderstorms on Tuesday and Wednesday.
-- End Changed Discussion --

&&

.MARINE...
Tonight, winds will become south-southeasterly as a warm front lifts
north of the area and increase to 10-15 knots. An associated cold
front will move east Saturday afternoon into the evening, allowing
winds to shift to become west-northwesterly at 5-10 knots into
Sunday. A very similar progression of another low over the Plains
will occur on Sunday into Monday as a warm front lifts north of the
lake on Sunday, increasing southerly winds to 10-15 knots. The most
notable winds of this forecast period will occur on Monday afternoon
as the associated cold front moves east across the area, shifting
winds to gain a more westerly component and increasing them to 15-20
knots. On Monday evening into the overnight, winds across the
central and eastern basin may briefly increase to 20-25 knots and
will be the period to monitor for any marine headlines. Boaters
should continue to monitor the forecast, especially given that
Monday is a holiday and increased boating is possible. In addition,
with warming Lake Erie temperatures, beach goers for the holiday
should be aware of the potential for rip currents and stay up to
date with the forecast. A secondary cold front is expected to move
southeast across the area on Tuesday into Wednesday, allowing winds
to become 10-15 knots from the northwest before high pressure builds
in on Thursday and winds becomes 5-10 knots.

&&

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

&&

$$

SYNOPSIS...Iverson
NEAR TERM...Iverson/Kahn
SHORT TERM...Griffin
LONG TERM...Griffin
AVIATION...Kahn
MARINE...Griffin