-- Discussion containing changed information from previous version are highlighted. --
082
FXUS61 KCLE 211051
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
651 AM EDT Tue May 21 2024

.SYNOPSIS...
Low pressure over the central United States will rapidly deepen
over the Midwest today as the low reaches western Lake Superior
tonight. A cold front from this well occluding low will move
across the area on Wednesday and settle near the Ohio River on
Thursday morning. High pressure will build behind the front for
Thursday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
-- Changed Discussion --
Very minor changes to the forecast with this update.
Temperatures were slightly cooler than current conditions and
have largely arrived at their morning lows across the area. Have
adjusted the temperature curve for the day based upon current
readings. Otherwise, have made some cosmetic tweaks to the sky
cover forecast based on current satellite conditions.

Previous Discussion...
Another well above normal temperature day is on tap for today,
as the forecast area resides in the warm sector of a deepening
low pressure system that will move through the Midwest toward
Lake Superior. Temperatures this morning will start not far off
from average highs and will just accelerate from there back to
the upper 80s to lower 90s and within close reach of record
highs for today. The limiting factor on temperature potential
will be the development of a lake breeze and scattered showers
and storms off the lake boundary. There was some moderate
success in convective initiation on Monday in Northwest Ohio and
this tapered temperatures down a degree or two across that
area, avoiding the 90 degree mark in some locations. For today,
the best moisture pool will be shifted further east from North
Central Ohio into Northwest PA and isolated to scattered showers
and storms should develop along the boundary this afternoon
mainly from Lorain County to NW PA but have an isolated mention
further west toward Sandusky and Toledo. Large surface based
instability and steep low level lapse rates across the region
will allow for any storms to have potential to bring down some
stronger winds. Any convection will subside with the diurnal
cycle this evening and most of the tonight period will be dry
with generally clear conditions and lows in the mid 60s to lower
70s.

Further west of the region today, a severe weather outbreak is
expected across the Midwest closer to the low pressure system
itself, as this system will be well supported by strong jet
energy and moving into a warm, moist environment that will
sustain a large thunderstorm complex. This complex will move
east across the Great Lakes region tonight toward the forecast
area. These storms will wane through the nighttime hours as loss
of diurnal heating will stabilize the low levels of the
atmosphere. However, enough jet energy should sustain convection
well through northern Indiana and southern lower Michigan and
there is a non-zero chance of thunder making it to Toledo before
dawn on Wednesday. The remnants of this complex will play a key
role in the severe weather and storm potential on Wednesday, as
the forcing of this feature will likely be the focus for new
storms over the forecast area. There is relatively high
confidence in this feature generating convection across the
upper Ohio Valley and eastern Great Lakes region. However, there
remains some question on the timing and precise location where
new convective initiation will be featured. The mean of guidance
suggests that new showers and storms will initiate along and
east of I-71 during Wednesday afternoon. However, some clusters
of guidance members are more progressive and have convection
reinvigorating further east and including less of the forecast
area. Thus, the shift in the location of the now Day 2 Slight
Risk for severe weather. Regardless, the thermodynamic
environment is fairly favorable with about 1500 J/kg of SBCAPE
over the eastern half of the area by Noon and dew points in the
mid 60s. The dynamics of the setup are a little less favorable
with 0-6 km bulk shear averaging 30 kt or so. Therefore, suspect
convection to be wind hazard dominant and organization more with
storm clusters and bowing segments vs. a well defined line of
storms with a widespread wind threat. Large hail is also
possible if an updraft can sustain itself, but it is a lesser
hazard with this setup.
-- End Changed Discussion --

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
There may be a brief lull in precipitation for the early part of
Wednesday night before additional showers and thunderstorms develop
along the cold front near or shortly after Midnight. At this point,
the atmosphere will be pretty worked over from any afternoon
convection and there won`t be much instability to work with so do
not anticipate a continued severe weather risk. With that being
said, precipitable water values will still be well above normal and
soils may be saturated from earlier heavy rainfall so will need to
keep an eye on the heavy rain/flooding potential. Showers/storms
should be progressive so the risk of training and the overall
flooding risk are low at this time. The front may be a bit slow to
exit southeastern zones on Thursday so there may be some lingering
showers/thunderstorms primarily south of the U.S. 30 corridor
through Thursday afternoon before weak high pressure very briefly
builds in from the northwest for Thursday night.

By Friday, a shortwave will lift northeast across the Ohio Valley as
a vertically stacked low begins to develop across the Upper Midwest.
There`s still quite a bit of uncertainty in how far north the
shortwave tracks; 00Z guidance has trended a bit farther north, but
would like to see a bit more consistency amongst runs before
increasing PoPs. Have chance PoPs Friday and Friday night with
higher PoPs to the south for the time being, but will continue to
refine as confidence increases.

Generally expect above normal temperatures through the short term
period with lows in the upper 50s to lower 60s and highs in the
upper 70s to lower 80s each day.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
The aforementioned vertically stacked low will lift north Saturday
and quasi zonal flow will likely develop across the region for the
start of the weekend. A few shortwaves may ripple across the area
through Sunday as a warm front begins to lift into the region and
from there guidance diverges quite a bit with additional shortwaves
or perhaps a more synoptically robust system on the table for the
latter half of Sunday through Monday. Regardless, there could be
periodic showers and thunderstorms throughout the long term period
with the highest precip chances with better forcing on Monday.
Temperatures won`t change much from the short term period with
maximum temps in the 70s and 80s and minimum temps in the upper
50s to lower 60s likely.

&&

.AVIATION /12Z Tuesday THROUGH Saturday/...
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VFR conditions should be expected at the terminals for the TAF
period today. Mid and high level clouds remain across the
airspace this morning with light southerly flow. Some clearing
has entered Northwest Ohio and will try to spread east through
the late morning hours. A lake breeze is expected to develop
and some diurnal cumulus is also expected across the region this
afternoon. Isolated to scattered showers and thunderstorms will
be expected in the lake breeze areas, especially NE OH and NW PA
this afternoon and have a brief VCTS at KCLE for possible TS in
the area. Other terminals remain low confidence for a TS mention
at this time. Winds will be southwesterly this afternoon with a
shift to the west then north with the lake breeze at KCLE and
KERI. Convection and cumulus will fade with sunset this evening
and southerly flow with largely clear conditions will be
expected through much of tonight. A thunderstorm complex will
develop across the Midwest today and push toward the airspace by
the end of the TAF period. Some residual showers and storms will
enter NW OH before 12z and have a vicinity mention at KTOL. Have
timed possible convection further east to KCLE with the longer
TAF. Overall, coverage is scattered and non-VFR is likely in any
TS that hits a terminal. Winds will increase out of the
southwest with gusts of 20 to 25 kt possible during the daytime
hours on Wednesday.

Outlook...Scattered to numerous thunderstorms are expected
Wednesday into Wednesday night and may bring a brief period of
non-VFR conditions. Scattered showers and storms on Friday and
Saturday could bring brief non-VFR conditions.
-- End Changed Discussion --

&&

.MARINE...
Southwest winds 5 to 10 knots will prevail across the majority of
the lake for most of today before a lake breeze produces onshore
flow in the nearshore zones this afternoon. Winds should shift to
the southeast this evening, but expect southwest flow to develop in
response to an approaching cold front by Wednesday morning with
winds increasing to around 15 knots. Behind the front, winds
diminish to 5 to 10 knots and briefly become westerly Wednesday
night before shifting to the south/southwest Thursday into the first
half of Friday. Anticipate east/southeast winds 10 to 15 knots for
Friday night through Saturday. As of now, no marine headlines are
expected unless winds trend higher with the deep warm air advection
on Wednesday.

&&

.CLIMATE...
High temperatures will approach record values today.

Daily Record High Maximum Temperatures

Date    Toledo         Mansfield      Cleveland      Akron          Youngstown     Erie
05-21   93(1941)       89(1941)       89(1941)       91(1934)       89(1934)       88(1911)

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Air Quality Alert until midnight EDT tonight for OHZ010>014-
     020>022-089.
PA...None.
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...Sefcovic
NEAR TERM...Sefcovic
SHORT TERM...Maines
LONG TERM...Maines
AVIATION...Sefcovic
MARINE...Maines
CLIMATE...CLE