459
FXUS61 KCLE 250809
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
409 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/...
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 MONDAY/...
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 /06Z Tuesday THROUGH Saturday/...
VFR conditions should persist across all terminals for the
remainder of tonight and for much of the day on Tuesday.
However, there is a large amount of uncertainty with how an
upstream MCS will impact the area Tuesday morning. Some hi-res
models suggest it weakening when others suggest it surging
south, and there is little agreement with the exact path it will
take. The highest confidence in the remnants impacting any
terminal is for KTOL and KFDY. The best timing for initial onset
of precipitation is generally around 15Z, but will need to
continue to monitor the ongoing convection and update as needed.
Once this surges south, a warm front will also be lifting north
and behind this boundary winds will increase from the south-
southwest to 12-15 knots, gusting up to 25 knots. Locally higher
winds are possible in any thunderstorms, along with reduction to
MVFR and possibly IFR visibilities. After sunset, winds will
weaken to 5-10 knots as a cold front approaches from the west.
Additional showers and thunderstorms are possible, but given the
spread in model agreement for the morning convection, opted to
just handle this with VCTS or a TEMPO for thunderstorms
producing MVFR distances. It is important to note that while
confidence remains low on exact timing and placement of weather
on Tuesday, there is a general consensus amongst models that
there will be impactful weather which may result in
visibility/ceiling reduction to non-VFR. Definitely a day to
keep an eye on the forecast and all updates as this will be an
evolving situation.

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 from 8 AM this morning to 7 PM EDT this
     evening for LEZ142>146.

&&

$$

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