361
FXUS61 KCLE 251521
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
1121 AM EDT Tue Jun 25 2024

.SYNOPSIS...
Low pressure will continue to move east across the northern Great
Lakes region, moving a warm front north today followed by a cold
front Wednesday. High pressure returns for Thursday and Friday
before another low pressure impacts the region this weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
11 AM Update...
Cancelled the severe thunderstorm watch for NW OH as the line of
convection has weakened and pushed east and south of the watch.
Expecting a continued downtrend with convection over the next
several hours with an area of stratiform rain and embedded
thunder impacting much of the area through mid afternoon before
diminishing. A few stronger storms are possible over the next
hour south of US-30 before the activity pushed south of the
forecast area. Attention will then turn to atmospheric recovery
across the area and any potential redevelopment of storms
across the area late this afternoon and evening, which is
looking increasingly unlikely given the nature of the ongoing
convection.

Original Discussion... To start off, this forecast is extremely
tricky given the upstream MCS currently ongoing and how this
will continue to evolve as it tracks south-southeast towards the
area. Hi-res models diverge quite a bit in the handling of this
system and there are multiple potential outcomes that can
impact the area. The first is that the MCS continues to decay,
reaching the northwest periphery of the area near 15Z and
resulting in locally gusty winds and heavy rainfall keeping
overall impacts fairly minor. The other potential outcome will
be that the strength of the MCS maintains and surges south
across Lake Erie, impacts a larger portion of the area with
strong winds, heavy rain, and isolated hail. There are many
factors that will determine how this evolves, including how much
instability will ramp up ahead of the MCS and more importantly
if that will be enough to break the cap. High EMLs and steep
mid-level lapse rates may be able to continue the decaying trend
of the MCS, but again if the instability ramps up quick ahead
of it then that may be enough to generate more surface based
storms and increase the potential for damaging wind gusts.

As this initial round of showers pushes south and continues to
decay, a warm front will move across the area late afternoon/early
evening, resulting in an increase of WAA and moisture across the
area. It is important to note that due to the models slowing the
progression of the warm front east, high temperatures for today are
not only forecast to climb into the low to mid 80s. There remains a
lot of uncertainty in any additional convection this afternoon and
into the overnight hour, specifically with uncertainty in how well
the atmosphere will recover after this mornings convection. Given
the increasing moisture and diurnally driven instability, opted to
maintain a chance of PoPs this afternoon into the evening ahead of
an approaching cold front. Temperatures tonight will drop into the
upper 60s to low 70s. To account for the potential of severe weather
today and tonight, SPC and WPC has placed much of the area in a Day
1 Marginal Risk for severe weather and excessive rainfall. Primary
concerns will be strong, damaging winds and localized flooding.

Late tonight and on Wednesday, a cold front associated with the
aforementioned low pressure will begin to move east across the area.
With good synoptic support and strong isentropic lift, expect
another round of showers and thunderstorms to impact the area for
Wednesday. To account for this severe potential, SPC & WPC has
placed much of the area in a Day 2 Marginal Risk for severe weather
and excessive rainfall. The primary hazard with these storms will be
damaging winds and efficient, heavy rainfall which may result in
localized flooding. High temperatures on Wednesday will climb into
the mid to upper 70s.

Again, it is important to note that this entire forecast is highly
dependent on the evolution of the ongoing MCS over the upper Midwest
and is valid to change/be adjusted in the coming updates as models
begin to handle the evolving complex better.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
The short term forecast period will be fairly quiet, especially
compared to the days before and day after the period. A cold front
will be exiting the forecast area on Wednesday night and have
quickly fading PoPs with clearing skies and falling temperatures
into the lower 60s. High pressure will build in behind the cold
front for Thursday and Thursday night and temperatures will be
cooler than normal in the 70s during the day. Clear conditions and a
decoupling atmosphere should allow for temperatures to fall
considerably on Thursday night into the 50s with some upper 40s here
and there, mainly NE OH and NW PA. The surface high pressure will
shift east for Friday and return flow back into the region will
allow for temperatures to climb back into the 80s. The return flow
will also allow for better moisture to return with 60 degree dew
points returning by evening. Shower and thunderstorm activity
upstream will start to enter the region on Friday night. While the
atmosphere will have more moisture to work with by Friday night, a
stabilizing air mass with nightfall will allow for just some
scattered convection with minimal concerns.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
A cold front with a supporting upper trough will move through the
region on Saturday and allow for widespread chances of showers and
thunderstorms. The intensity of convection will be based mainly on
the timing, which at this point could be during the afternoon hours,
so storms could have some punch with them. Temperatures before any
showers and storms  on Saturday could rise into the upper 80s and
perhaps give 90 degrees a brief tap, if the system slows up a bit.
The trend for Sunday into Monday will be dry with high pressure
building back into the region and temperatures will remain slightly
below normal with the cooler air mass in place behind the cold
front.

&&

.AVIATION /12Z Tuesday THROUGH Saturday/...
Pleasant aviation conditions this morning with winds from the
south at 5-10 knots will become less desirable beginning mid to
late morning, especially for KTOL. An MCS continues to trek
across central Michigan this morning and is expected to impact
NW OH between 13-16Z with strong, damaging wind gusts and heavy
rainfall the primary concern. Conditions in these storms will
quickly diminish to IFR, but possibly MVFR, as heavy rain
reduces visibilities at KFDY and KTOL. The remainder of the
terminals will likely see precipitation onset late this
morning/early afternoon, although impacts should remain minimal
for these terminals. As the environment tries to recover this
afternoon, there is an additional threat for scattered showers
and thunderstorms across the area, but confidence in timing and
location is fairly low at this point as it is highly dependent
on what happens over the next couple hours. Opted to handle the
uncertainty with VCTS at most terminals, but cannot rule out
MVFR conditions in any terminals that get storms. By Wednesday
morning, a cold front will move towards the area, bringing
widespread showers and thunderstorms and lowering ceilings to at
least MVFR conditions. Quite a messy aviation day going forward,
but storms should not be widespread until late tonight/early
Wednesday morning.

Winds from the southwest will quickly ramp up this morning to
12-16 knots, gusting up to 20-25 knots through the afternoon
hours. After sunset, winds will weaken to 5-10 knots and remain
from the southwest through the end of the period.

Outlook...Non-VFR possible in showers and thunderstorms today
and Wednesday. Non-VFR possible again in showers and
thunderstorms on Saturday.

&&

.MARINE...
High pressure will continue to the east of the region today and
return flow with south to southwest winds behind a warm front will
persist across the lake. The pressure gradient and surface winds
will increase later this morning and into the afternoon as a storm
complex enters from the northwest and will allow for winds of 20-25
kt for a 6-8 hour period. Believe the 20 kt sustained mark gets to
about Cleveland and have extended the Small Craft Advisory east. The
window for stronger winds is later than previously forecasted and
have a later end time to encapsulate the entire event. Showers and
storms will be possible across the basin today and tonight and
convective marine headlines will be possible. A cold front will
cross the lake on Wednesday and flow will become northwest. The
pressure gradient over the lake does not look impressive enough to
have substantial northwest flow to allow for a great increase in
waves. Flow will become lighter and northerly with high pressure on
Thursday. Southeast flow returns to the lake on Friday with a warm
front lifting across the region, as high pressure moves east. A cold
front will cross the lake on Saturday. Southwest flow will increase
ahead of the feature and could approach the need for a headline.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...Small Craft Advisory until 7 PM EDT this evening for
     LEZ142>146.

&&

$$

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