011
FXUS61 KCLE 042350
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
750 PM EDT Thu Jul 4 2024

.SYNOPSIS...
A front currently stalled near the route 30 corridor will lift
north across the area tonight ahead of low pressure drifting
into the western Great Lakes. This low pressure will pass by to
our north Friday evening while pushing a cold front through.
Weak troughing will linger for Saturday before high pressure
builds in Saturday night through Monday.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
6:00 PM Update...
Area of showers associated with the MCV has continued moving
eastward, now located generally east of I-77. Shower
development has been on the rise over the past couple hours to
our west in northern Indiana and western Ohio, with these
showers spreading eastward into the forecast area this evening
into tonight. Lightning has trended downward, and there`s
actually no lightning with any of the activity mentioned above.
Instability has also been lowered and is expected to continue
diminishing tonight, so greatly reduced the chance of
thunderstorms through tonight with this update.

Previous Discussion...
Unsettled and humid conditions are expected for the near term.
Weak low pressure will push into the Great Lakes from the west
tonight into Friday ahead of an upper-level trough. A front
currently draped across central OH will lift north as a warm
front this evening into tonight. The low pressure will pass to
our north late Friday into Friday night while pushing a cold
front across the region. Along with the fronts, lift from
convective-enhanced shortwaves and MCVs will move through at
times, encouraging occasional shower and thunder potential.

As of 3:30 PM the front is draped from roughly Marion to
Mansfield to Chardon to Meadville with several low-topped
convective cells ongoing along it. At the same time, an MCV is
moving across central OH. The combination of the two features
will keep shower and thunder chances going through early this
evening along and south of the front, with some lighter
stratiform rain possible north of the front. In the immediate
term, the combination of enhanced flow aloft with the MCV and
the boundary itself may encourage rotating updrafts from
Mansfield to Canton points south. However, skinny and modest
instability profiles and a lack of DCAPE argue against severe
weather. Still, any more persistent rotating updrafts will need
to be watched for a brief/isolated severe threat through about 5
PM in our far south, with any slower-moving or training storms
dropping locally heavy rain in this humid environment. The next
convectively-enhanced shortwave is currently moving east out of
central IL and will move through tonight. Modest lift ahead of
this feature along with weak instability and a humid airmass
will support another uptick in showers and thunder from west to
east this evening into tonight. The frontal boundary will begin
lifting ahead of this feature and may be a focus for more
numerous cells this evening. The wave will exit to the east
after midnight, allowing for a drying trend overnight. With
such a humid airmass and light winds a bit of patchy fog may
develop pre-dawn Friday if a period of partial clearing occurs.
Otherwise, look for muggy lows on either side of 70.

We should see a general lull in activity through much of Friday
morning due to weak subsidence and perhaps a bit of dry air
advection behind the shortwave that will move through tonight.
By Friday afternoon and evening, modest height falls and upper-
level divergence ahead of the upper trough moving into the Great
Lakes along with the approach of the cold front should encourage
at least some shower and thunderstorm development across our
area. Guidance disagrees on how quickly subsidence behind
tonight`s wave will exit and on if convection will fire over
the Ohio Valley on Friday. Both could be limiting factors for
destabilization and subsequent convection local. However, still
have a mix of chance and likely POPs along and ahead of the
cold frontal passage from west to east Friday afternoon and
evening as the combination of a front, some forcing, a humid
airmass and timing near peak heating should yield at least some
convection. There is room for POPs to be adjusted higher or
lower depending on how much subsidence lingers over our area and
how robust the return of greater moisture/instability is from
the south/southwest through the day. Either way, expect muggy
conditions with highs generally in the low to mid 80s Friday.

Poor mid-level lapse rates will act against a greater severe
threat Friday afternoon and evening. However, stronger heating
could yield 1000-2000 J/KG of MLCAPE given such a moist airmass
and deep-layer shear of 40-50 knots is expected. Enough surface
heating and mid-level drying may play out to allow moderate
DCAPE to develop as well. Given a number of conflicting factors,
the current Day 2 Marginal Risk (level 1/5) for severe weather
driven by isolated damaging wind potential is reasonable.
However, there is a somewhat less-likely potential for greater
destabilization and more robust convection. Given the amount of
shear, a more robust evolution could support a mix of supercells
and small lines with a more organized wind damage threat and
potentially some marginally severe hail and tornado potential.
This may come down to a "nowcast" situation on Friday.

Activity should gradually exit to the east and diminish in
intensity Friday evening and night as the cold front continues
progressing with some clearing of the skies too. Lows will
generally fall in the mid 60s to near 70 by early Saturday.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
While the model data is not completely supportive, have added slight
chance POPs to the land portion of the CWA for Saturday given the
cold pool aloft moving in and some instability off the boundary
layer combined with peak daytime heating and perhaps a hint of PVA
aloft. Layer moisture is definitely a concerning factor and a reason
not to go above 20 percent, but could get an isolated shower to form
in this setup. Vast majority of the area will be dry. High pressure
will continue to build in the southern Great Lakes, paving the way
for a dry remainder of the weekend. Slightly warmer Sunday with
generally low to mid 80s for the most part. An upper level trough
will be working its way into the western Great Lakes by the end of
the short term forecast period, likely weakening as it does so.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Upper trough south of the axis in the Great Lakes mentioned at the
end of the short term period will be the main driver for the next
chances for showers and storms for the region. Until then, high
pressure should still be in control for one more day on Monday, but
will be on the exit to the east. Best bet for the surface low
pressure/cold front to come through is Tuesday afternoon/evening.
POPs linger in cyclonic flow aloft through mid week in the wake of
the system.

&&

.AVIATION /00Z Friday THROUGH Tuesday/...
Rain showers have developed west of I-71 with coverage of rain
expected to increase and spread eastward across the rest of the
area through the next few hours. Variable conditions within
showers are expected but VFR/MVFR conditions most likely,
although brief IFR with visibilities down to 2 SM will be
possible. Once this activity moves to the east we will see a
lull in precipitation late tonight into Friday morning, though
with the humid airmass and light winds in place some non-VFR
ceilings and visibility may develop for a few hours Friday
morning, especially along and south of US-30 where IFR and even
LIFR will be possible, primarily with ceilings. Isolated to
scattered convection likely re-develops Friday afternoon though
there is still a good deal of uncertainty with timing and areal
convection. Limited VCTS mention to KCLE and KMFD where hi-res
guidance has the greatest chance for thunderstorms.

Winds are light and variable through tonight, becoming
southwesterly 8-13 knots Friday afternoon.

Outlook...Non-VFR possible in showers and thunderstorms late
Friday into Friday night.

&&

.MARINE...
Light and variable winds through early Friday morning with wave
heights less than 1ft become southerly around 10kts Friday afternoon
ahead of a cold front with chances for showers and storms, then
southwesterly 10-20kts in the wake of the cold front Friday evening
through Saturday. Wave heights east of Cleveland 1-3ft during that
time, west of Cleveland 1-2ft away from shore in the nearshore
zones. Winds ease out of the northwest Sunday with wave heights
dropping below 1ft despite the more onshore flow at around 5kts.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...Sullivan
NEAR TERM...Saunders/Sullivan
SHORT TERM...26
LONG TERM...26
AVIATION...Saunders
MARINE...26