023
FXUS61 KCLE 151404
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
1004 AM EDT Mon Jul 15 2024

.SYNOPSIS...
A frontal boundary will settle across the Great Lakes through
Tuesday before pushing southeast across the area as a cold front
Tuesday night into early Wednesday. High pressure will build in
from the west Wednesday night through the end of the week.

&&

.NEAR TERM /THROUGH TUESDAY/...
950 AM...
Two remnant MCVs were noted across the area this morning across
eastern MI and central OH. The stronger of the two appears to be
the one in eastern MI, with convection continuing to pulse up
along the front flank across southern Ontario and the eastern
half of Lake Erie. Will be monitoring the eastward-moving
remnant outflow currently along the I-71 corridor for
redevelopment later this morning and early afternoon across
portions of NW PA. A brief window of severe weather will exist
roughly between 1-3 PM across NW OH. Better chances will exist
further east across portions of western NY. Otherwise, large-
scale subsidence behind these convective complexes suggest a
mostly-dry and sunny forecast for this afternoon and evening.
Increased high temperatures into the lower 90s with heat indices
expected to reach the upper 90s.

Previous Discussion...
Our warm and humid, unsettled pattern continues through the
near term. Forecast uncertainty remains higher than normal due
to the dependence on the evolution of multiple rounds of
convection both overhead and upstream through Tuesday.

The remains of an MCS are approaching the I-75 corridor as of
12z/7 AM with no remaining lightning. Warm air advection ahead
of this remnant MCS is encouraging a few thunderstorms over
extreme northeast OH that are shifting into northwest PA. The
light showers will likely push into our northwest OH counties
over the next couple of hours before completely dissipating.
Isolated showers/thunder may continue to develop ahead of this
feature but most will stay dry. Outside of small hail and gusty
(sub-severe winds) am not expecting any hazards this morning
beyond the typical lightning with any thunderstorms this morning
across Lake Erie and adjacent extreme northeast OH and
northwest PA. Gave POPs a heavy edit with the 6:30 AM update and
generally reduced them notably this morning, though do hang on
to relatively higher POPs from northwest OH across Lake Erie
into extreme northeast OH and northwest PA, as these areas stand
the best shot at getting at least a bit of rain this morning.

We should see lull in activity spread in from the west-
northwest later this morning into this afternoon as we get into
subsidence and a worked over airmass behind the MCS and MCV. The
MCV will pass close to Erie, PA early this afternoon and
renewed thunderstorm development may begin ahead of it over
Northwest PA before spreading southeast. Farther west, expect an
outflow boundary to settle across our far southern counties
(likely near or south of a Marion-Akron-Warren-Meadville line)
into this afternoon that may be a focus for isolated to
scattered thunderstorm development after 1-3 PM. Synoptic
forcing is weak this afternoon and it`s uncertain where exactly
the outflow boundary settles so confidence remains somewhat low.
This morning`s MCS dissipating on the quicker side may point to
greater odds of destabilization and afternoon development across
along/ahead of the outflow boundary. Overall, have 30-60% POPs
across our southern/southeastern counties this afternoon with
drier conditions farther north. A strongly unstable airmass will
develop south of the outflow boundary this afternoon, so if we
see re-development across our far southern/southeastern counties
it will carry a conditional risk for locally damaging winds and
perhaps marginally severe hail. Given clouds/rain this morning
and a worked over airmass lowered high temps a bit today...ranging
from the low to mid 80s in northwest PA to the mid 80s to near
90 in Ohio. Peak heat index values may still reach the mid to
upper 90s (advisory criteria is 100F) from Toledo to Marion
points west with values ranging from the upper 80s to mid 90s
elsewhere.

Any re-development across our far south should exit and leave a
lull for several hours this evening into tonight. We will (once
again) then turn our attention towards the Chicago area as the
next shortwave is expected to encourage another robust MCS to
develop out that way. Any MCS would spread east-southeast along
the instability axis overnight tonight into early Tuesday. As we
saw last night into this morning, MCSs can weaken quickly once
they out-run the greater forcing and shear, so what state any
cluster is in as it moves into our area overnight tonight or
very early Tuesday is quite uncertain...as illustrated by the
SPC Marginal (risk level 1/5) risk for severe weather. However,
there may be some arguments for any MCS tonight to hold its
intensity longer...there will be a bit more shear, especially
upstream, and less convection over our region during the
afternoon and evening hours than yesterday may allow for more
instability to build in as we will be on the edge of an
extremely unstable airmass. We will as always closely monitor
trends both overhead and to our west today in sizing up our
thunderstorm/severe potential overnight tonight into very early
Tuesday, as if we see a more organized MCS spread in it would
carry some form of wind damage risk. Expect lows tonight to
range from the upper 60s to mid 70s. Currently spread 40-60%
POPs in after midnight, though expect refinement in the
timing/magnitude.

Showers/storms have a decent likelihood to still be ongoing
across parts of our area Tuesday morning. How quickly this
activity exits will heavily dictate how widespread and intense
thunderstorm development ahead of an approaching cold front is
Tuesday afternoon. Shear and forcing will be a bit stronger over
the local area on Tuesday as the front approaches but
instability may end up being a limiting factor if we are too
worked over from any storms late tonight into Tuesday morning
and struggle to re-cover. Either way, have POPs ramping up to
the 60-70% range for most of the area (a bit lower towards
Toledo) Tuesday afternoon and evening. With a very moist airmass
and storm motions nearly paralleling the approaching cold front
locally heavy rain and flash flood may also be concerns Tuesday
afternoon and early evening. Lowered highs a bit on Tuesday,
now generally ranging from the mid to upper 80s. Dew points in
the 70s may still bring heat index values into the low to mid
90s but advisory criteria values look to be avoided.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
Convection that develops Tuesday afternoon/evening is likely to
persist into Tuesday night. However, despite the cold front
slowing/stalling to just north of our forecast area, a lot of model
guidance is starting to shift south of convection Tuesday night. The
NAM is one model that is still holding onto the idea of persisting
convection and heavy rain through much of Tuesday night, however the
overall trend is a southward shift. This is captured by WPC`s latest
D2 ERO where the slight risk area now only encompasses from
Youngstown to Marion (and points south). The severe risk will likely
be waning through Tuesday night.

The aforementioned cold front moves south across the area early
Wednesday morning through early Wednesday afternoon. Lingering
isolated showers and thunderstorms will be possible ahead of this
cold front. With abundant deep-layer shear, would not be surprised to
see a stronger/spiny storm or two, but the severe risk is
minimal for Wednesday.

High pressure gradually builds in behind this cold front, with dry
weather Wednesday night and onward. The airmass accompanying this
high is cooler as well, with high temperatures in the upper 70s to
low 80s on Wednesday and mid 70s on Thursday (running about 6-10
degrees below normal. Thursday night could even be a touch chilly
for some with overnight lows in the mid to upper 50s.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
High pressure becomes centered over the region by Friday, with the
high remaining steady but gradually weakening through Saturday and
Sunday. A gradual rebound to the temperatures are expected through
the weekend with highs back in the low to mid 80s on Saturday and
Sunday. With no precipitation and low humidity, it should be a
rather pleasant summer weekend.

&&

.AVIATION /12Z Monday THROUGH Friday/...
A decaying cluster of showers is approaching TOL and FDY. A few
showers and storms across extreme Northeast OH are moving east.
This decaying cluster may bring some light showers (no
restrictions expected) to TOL, FDY, and perhaps CLE this
morning. Some thunderstorms may develop from MFD, CAK, YNG and
ERI points east/southeast this afternoon before exiting
southeast by this evening. A lull is expected for several hours
tonight before the next cluster of showers and storms approaches
from the west pre-dawn Tuesday. Outside of any thunderstorms
mainly VFR is expected, though some brief MVFR ceilings are
possible this morning, especially at TOL.

Winds turn southwest while increasing to 8-14 knots with some
gusts 20-25 knots this afternoon. Higher winds and gusts will
occur in any thunderstorms.

Outlook...Mainly VFR outside of occasional thunderstorms through
Tuesday evening.

&&

.MARINE...
Starting off this morning with southwest winds generally in the 10
to 15 knot range. A Mesoscale Convective Vortex (MCV; a low caused a
large cluster of thunderstorms) is expected to move just north of
Lake Erie later today. Latest model guidance suggested a brief
period of 3-6 hours of enhanced wind speeds in the 20-25 knot range
late this morning through the afternoon hours. Confidence is
somewhat low in this occurring but will continue to monitor
observations today to see if this materializes and some sort of
headline needs to be a issued.

By tonight, conditions become a bit quieter (outside of any
thunderstorms that cause issues) with flow of 5-10 knots out of the
south. Southwest winds increase to 10-15 knots out of the southwest
on Tuesday with a possibility for brief periods of 20 knot winds at
times during the day time hours. Winds weaken Tuesday night,
becoming 10-15 knots generally out of the north by Wednesday
afternoon following a cold frontal passage. Winds become light and
variable by Friday as high pressure gradually builds in from the
west.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Beach Hazards Statement until 8 PM EDT this evening for OHZ012-
     089.
PA...Beach Hazards Statement until 8 PM EDT this evening for PAZ001.
NY...None.
MARINE...Small Craft Advisory until 4 PM EDT this afternoon for
     LEZ142>146.
     Small Craft Advisory until 8 PM EDT this evening for
     LEZ147>149.

&&

$$

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