344
FXUS61 KCLE 230758
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
358 AM EDT Sun Jun 23 2024

.SYNOPSIS...
A cold front will move east this afternoon before high pressure
builds in for Monday and Tuesday. Another cold front associated with
a low pressure over Ontario will move east across the area on
Wednesday before high pressure returns for the end of the work
week.

&&

.NEAR TERM /THROUGH MONDAY/...
Currently, a broad trough aloft is providing support for a surface
low pressure to continue to move northeast through the western Great
Lakes region. The area currently lingers in the warm sector of the
low pressure with temperatures across the area in the 80s and
dewpoints lingering in the mid to upper 60s. Looking upstream across
northern Indiana, a line of convection continues to track east,
gradually weakening in terms of intensity, but still maintaining
widespread thunderstorms with gusty winds and lightning. A LLJ of 40-
45 knots has moved across the area resulting in non-convective gusty
winds up to 20 knots this morning. This LLJ and mid-level support
should be enough to maintain the line of convection, where locally
higher gusts are possible. In the heaviest storms, expect very
efficient rainfall of over 1"/hr as PWAT values climb over 2" and
warm cloud layers deepen to over 13 kft. With this overall limited
instability this morning, still expecting a general weakening trend
with locally higher wind gusts and heavy rain possible.

The trickier part of the forecast is for this afternoon as the
aforementioned line of convection exits east of the area late
morning. This afternoon, the cold front is expected to push east
across the area, stirring up another potential round of scattered
convection. Many ingredients, including a moist boundary layer,
increasing instability to 1000-1500 J/kg, and a lingering LLJ will
couple with strong isentropic ascent along the boundary to provide
enough support for additional storms development along and east of I-
71. Primary concern with any storms that develop with be strong
damaging winds, although with effective shear values of 20-30 knots
isolated large hail cannot be ruled out. In addition to the severe
potential, the PWAT values remaining over 2" and deep warm cloud
layers will produce heavy rainfall. In areas that received
precipitation with the initial round of storms, may see some
flooding especially in urban and low lying areas. The biggest
question mark with this forecast is in regards to how fast the
atmosphere will be able to recover behind the initial round of
convection. Widespread clouds are expected today which typically
would limit instability and potentially limit convection, but given
the strong surface lift and moisture rich environment confidence is
low that the clouds will have as strong of an effect. To highlight
these threats, SPC has issued a Slight Risk SWO for the far eastern
counties and a Marginal Risk SWO for the remainder of the areas
along and east of I-71. In addition, WPC has issued a Day 1 Marginal
ERO for those far eastern counties.

Showers and thunderstorms should primarily dissipate once the cold
front pushes east late this evening. A few showers and storms may
linger into late evening, but with a northwest flow becoming
established across the area, colder 850mb temperatures near 10C will
begin to push across Lake Erie and transition the lingering
precipitation to primarily be lake enhanced with limited thunder
potential. By mid-Monday morning all precipitation should end across
the area as high pressure becomes established over the area.

High temperatures today and Monday return to more seasonal, climbing
into the low 80s for much of the area with the portions of the
eastern counties possibly only reaching into the upper 70s.
Overnight lows tonight will drop into the low 60s.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
A dry, stable pattern will allow for a pleasant night on Monday with
temperatures falling below 60 degrees for a large portion of the
forecast area - first time in about 2 weeks! Unfortunately, the
remainder of the short term period will feature a more active
pattern and return to warmer temperatures and high humidity. Surface
high pressure will move east for Tuesday and return flow across the
region will allow for temperatures to soar back into the upper 80s
to lower 90s and dew points reach the 60s again. A minor shortwave
will move through the region on Tuesday and allow for some small
shower and storm chances, but the main show appears to be on
Wednesday as better synoptic forcing will enter the region with a
larger upper trough and surface cold front. Have PoPs increasing to
likely and even categorical for Tuesday night into Wednesday. Have
come concern about severe weather potential for Wednesday, as the
present consensus for the timing of the main synoptic forcing
features is Wednesday afternoon and evening, which coincides with
peak heating of the day with upper 80s and near 70s dew points that
would support a fairly robust thermodynamic environment for storms.
This day will be one to watch moving forward.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
Thursday should be a repeat of Monday with high pressure entering
behind the main synoptic system, allowing for a dry, stable
environment with cooler than normal temperatures and pleasant
conditions. The surface high will shift east on Friday as the ridge
axis enters and return flow once again enters the region with highs
achieving the mid to upper 80s again. A shortwave will override the
ridge later on Friday into Saturday, followed by a stronger upper
trough for the weekend. This will once again contribute to an active
pattern with increasing storm potential for the weekend.

&&

.AVIATION /06Z Sunday THROUGH Thursday/...
Widespread VFR conditions are being observed across the area
this morning ahead of an approaching line of storms being
observed in northern IL/IN and southern MI. This line of storms
will continue to progress east towards the region this morning,
initially impacting KTOL and KFDY between 08-09Z. Within these
showers, heavy rainfall will likely reduce visibilities to MVFR
distances, possibly IFR in the heaviest showers. There is an
overall weakening trend with the line given the diurnally
unfavorable environment, but still expected thunder to be heard
at most stations through this morning. This initial line will
depart east by late morning, but a secondary round of storms is
expected along the cold front that move east today. Highest
confidence in the storm potential is along and east of I71,
although if western counties rebound quick enough cannot rule
out a thunderstorm or two for KTOL and KFDY. Confidence in this
occurring is limited, so opted to only mention additional
thunder at terminals east of those. Quite a bit of uncertainty
remains with the strength of convection this afternoon given
these morning storms, but any terminal impacted will likely see
periods of MVFR and possibly IFR given the heavy rain potential.
In addition, MVFR ceilings will push east along the cold front,
but should rebound for all terminals around sunset tonight.

Southwest winds this morning will ramp up to 10-15 knots,
gusting up to 25 knots into the early afternoon. Behind the cold
front that moves through, winds will shift to become
northwesterly at 10-15 knots with gusts up to 25 knots
initially, but are expected to quickly weaken by 00Z Sunday to
be 5-10 knots across the area.

Outlook...Non-VFR possible in scattered showers and
thunderstorms across Northeast Ohio and Northwest Pennsylvania
Sunday night into Monday. Additional non-VFR possible in showers
and thunderstorms Tuesday evening through Wednesday.

&&

.MARINE...
After a rather benign marine weather week, the weather will be more
active this week with several windows for marine headlines, several
widespread storm chances, and generally increased winds across the
lake. For today, southwest flow will increase ahead of a cold front
this morning, winds will get close to 20 kt and will have a Small
Craft Advisory for the winds starting this morning. The front and
convection will cross the region later today and onshore flow will
increase wave action, which will allow for a longer period for the
Small Craft Advisory and these areas will be the land zones with the
Beach Hazards Statement for increased swimming risk with the higher
waves. Have tweaked the areas and timing of the marine hazards this
morning just slightly to align with the current wind and wave
forecasts. High pressure across the region on Monday will allow for
decreasing northwest flow during the day, followed by light and
variable flow overnight. Return flow on the back side of the high on
Tuesday will allow for increasing south to southwest winds and there
are some minor chances for showers and storms. A potent cold front
will enter for Wednesday and bring widespread showers and storms to
the region. Southwest flow will increase ahead of the front to at
least 15 kt during the day on Wednesday. Winds will shift to the
northwest behind the front on Wednesday night and will increase
waves. This window could potentially need a Small Craft, but the
forecast remains below at this time. High pressure will return to
the region for Thursday and bring decreasing northerly flow.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Beach Hazards Statement from 11 AM EDT this morning through
     late tonight for OHZ010>012-089.
PA...Beach Hazards Statement from 11 AM EDT this morning through
     late tonight for PAZ001.
NY...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for
     LEZ142>144.
     Small Craft Advisory from 8 AM this morning to 4 AM EDT Monday
     for LEZ145>147.
     Small Craft Advisory from 11 AM this morning to 4 AM EDT
     Monday for LEZ148-149.

&&

$$

SYNOPSIS...Campbell
NEAR TERM...Campbell
SHORT TERM...Sefcovic
LONG TERM...Sefcovic
AVIATION...Campbell
MARINE...Sefcovic