-- Discussion containing changed information from previous version are highlighted. --
524
FXUS61 KCLE 112039
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
439 PM EDT Sat May 11 2024

.SYNOPSIS...
Low pressure will cross into New York tonight with a trough
lingering across the Great Lakes. High pressure will build
across the region Sunday but quickly move east Sunday night and
Monday as low pressure approaches from the Midwest and a cold
front sags slowly southward through the Great Lakes.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
A strong cold front currently bisects NE Ohio and is positioned
roughly from Lake County to Knox County. Convergence along this
boundary combined with afternoon heating beneath cooling temps aloft
(850 mb temps will reach 1-2 C this evening) is resulting in a line
of loosely organized convection. The steepening low and mid-level
lapse rates associated with this cold pool aloft is resulting in a
lot of hail reports with this convection. Most calls and social
media posts have reported between pea and half inch diameter hail,
but given the aforementioned steep lapse rates and mesoanalysis
showing 500-1000 joules of SBCAPE, an isolated severe storm with
hail up to 1 inch diameter and downburst winds of 50-60 mph is
possible. A nice jet streak rounding the base of the digging
mid/upper trough has enhanced lift and resulted in locally up to 60
knots of low-level shear immediately along the cold front as sampled
by the KPBZ VAD wind profile, so this supports the possibility of a
severe storm or two this afternoon during peak heating despite the
marginal thermodynamics. Any strong to severe storm would likely be
between now and 21Z as the cold front crosses the remainder of NE OH
and NW PA. Otherwise, expect showers and occasional thunderstorms
with small hail to blossom across the rest of north central and NE
Ohio this afternoon and evening as the cold air aloft deepens over
the low-level heating, so have likely PoPs in most inland areas. NW
Ohio will see some showers too, but they should be less widespread.
This activity will diminish rather quickly as we approach sunset
since it is diurnally driven and disorganized, so have PoPs
decreasing fast after 00Z.

Moving into tonight, the axis of the mid/upper trough will swing
into the eastern Great Lakes, with an associated closed low dropping
from Lake Huron into central New York. Continued cold air advection
and cyclonic flow, fairly deep wraparound moisture, and WNW flow
across the lake will generate lake enhanced showers over the primary
snowbelt of NE Ohio and NW PA. With 850 mb temps of 1-2 C over lake
surface temps averaging 10-13 C and the wraparound moisture, there
will be a couple hundred joules of lake induced CAPE. Some boundary
layer shear will prevent the rain from being overly heavy, but
expect showers to be quite persistent in far NE Ohio and NW PA
tonight, so kept high chance to likely PoPs in that area through
late tonight. Drier air and high pressure building eastward late
tonight will slowly diminish the showers, so all areas will be dry
by mid morning on Sunday. As the surface high slides across the Ohio
Valley Sunday, skies will clear leading to mostly sunny skies for
the afternoon, although it will still be on the cool side given the
lingering mid/upper troughing over the eastern Great Lakes. Another
mid/upper trough and associated cold front will drop toward the
Great Lakes Sunday night, so have chance PoPs for showers Sunday
night.

Lows tonight will fall into the low to upper 40s, with upper 40s to
upper 50s Sunday night. Highs Sunday will reach the mid 60s to low
70s in most areas, with low 60s in far NE Ohio and NW PA.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
-- Changed Discussion --
Upper-level trough extends from Canada into the northern Great
Lakes along with another upper-level trough lifting northeast
out of the central Great Plains. At the surface, a modest low
pressure system (~1004mb) will accompany the trough out of the
Great Plains with a separate cold front moving southeast across
the Great Lakes region. Precipitation will be isolated/scattered
Monday afternoon through the first half of the night before
becoming more likely during the day Tuesday as the low pressure
approaches from the west-southwest and cold front from the
northwest. Scattered rain showers are possible Tuesday night as
the low departs. Temperatures will be warm on Monday with highs
in the upper 70s before cooling down on Tuesday as that
aforementioned cold front moves through with highs down into the
upper 60s.
-- End Changed Discussion --

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
-- Changed Discussion --
Upper-level ridging and surface high pressure builds in
Wednesday and Thursday, though there could be some lingering
isolated showers on Wednesday, mainly in the southern part of
the CWA but should be precipitation-free Wednesday night through
Friday morning. Upper-level trough and surface low move across
the region Friday evening through Saturday. There is a lot of
spread in model guidance still, so decided to hold with broad
chance PoPs during this period for now. Temperatures are
expected to rebound into the 70s Thursday through Saturday.
-- End Changed Discussion --

&&

.AVIATION /18Z Saturday THROUGH Thursday/...
Tricky TAF forecast this afternoon and evening in terms of the
timing of the showers and thunderstorms. The wave of steadier
rain that brought MVFR this morning has exited east of the area
allowing most terminals to return to VFR. However, convection is
developing along the cold front currently located over NE Ohio.
This is expected to become more widespread this afternoon as
deepening cold air aloft combined with afternoon heating
steepens lapse rates, with the greatest coverage expected over
NE Ohio and NW PA. However, it will not rain everywhere or all
of the time, so used VCSH and VCTS to reflect these convective
showers and thunderstorms. Brief drops to MVFR or IFR will
accompany the heaviest showers/storms, but since it`s impossible
to pinpoint that, did not put the lower flight categories in
the TAFs. Drier air will gradually work eastward late this
evening and tonight, so expect KTOL, KFDY, and KMFD to be dry
by mid evening, but expect chances for a few showers to persist
farther east until late tonight or Sunday morning, especially at
KERI where some lake enhanced rain showers are expected. This
will even support some MVFR cigs in NE Ohio and NW PA
overnight. Dry conditions and clearing skies are expected by
late Sunday morning as high pressure builds in.

W to NW winds of 15-20 mph will gust up to 25-35 mph in the
cold air advection this afternoon before turning more NW and
gradually diminishing to 5-10 knots tonight and Sunday morning.

Outlook...Non-VFR possible in showers Monday, Tuesday, and
Wednesday.

&&

.MARINE...
-- Changed Discussion --
West winds of 15 to 20 knots turn northwest this evening through
tonight, with winds gradually weakening through the morning
hours. Small craft advisory is out through this evening and
tonight. High pressure ridge moves east across the region on
Sunday, with winds becoming southwest Sunday night through
Monday night as low pressure approaches from the southwest and a
separate cold front approaches from the northwest. Weak
northeast winds develop behind the cold front Tuesday through
Wednesday.
-- End Changed Discussion --

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...Small Craft Advisory until 10 PM EDT this evening for
     LEZ142>144.
     Small Craft Advisory until 10 AM EDT Sunday for LEZ145>148.
     Small Craft Advisory from 11 PM this evening to 8 AM EDT
     Sunday for LEZ149.

&&

$$

SYNOPSIS...Garuckas
NEAR TERM...Garuckas
SHORT TERM...Saunders
LONG TERM...Saunders
AVIATION...Garuckas
MARINE...Saunders