641
FXUS61 KCLE 190012
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
812 PM EDT Fri Jul 18 2025

.SYNOPSIS...
A warm front lifts northeast across the area on Saturday,
followed by a cold front on Sunday. High pressure builds in for
Monday and Tuesday. A warm front crosses on Wednesday, ushering
in additional heat and humidity.

&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
The flat shortwave that provided for a rainier than expected
Friday along and south of the US 30 corridor is exiting. This
will allow weak surface high pressure to take control through
the night, bringing partly to mostly clear skies and dry
conditions. With light to nearly calm winds expected tonight
and relatively small temperature and dew point spreads already
in place, conditions will be conducive to fog development late
tonight into very early Saturday. The potential for some clouds
to linger through the night casts uncertainty, though did add
fog to the forecast for more rural and lower-lying inland
locales. It will be another pleasant night, with lows ranging
from the upper 50s in rural interior PA and even extreme
northeastern OH to the low to mid 60s across most of the area.

Active weather returns later Saturday afternoon into Saturday
night. A warm front will lift across the area on Saturday,
bringing the area into the warm sector and allowing moderate
instability (MLCAPE 1000-2000 J/KG) to build into Northwest and
Central OH by late afternoon. A later warm frontal passage will
likely lead to a CAPE gradient with a decrease across Northeast
OH and Northwest PA. A shortwave will approach out of the
southern Great Lakes late Saturday afternoon and cross the area
the first half of Saturday night. The main focus for shower and
storm potential will likely develop over MI and IN Saturday
afternoon, well within the warm sector and closer to the lift
with the approaching shortwave, and spread east-southeast across
Northwest and North Central OH late Saturday afternoon and
evening. Guidance suggests this convection will likely grow
upscale into a cluster or MCS (mesoscale convective system),
which makes sense given some forcing, fairly high atmospheric
moisture, and uncapped instability. Some cells may develop
ahead of any line or MCS moving in from the west, given
gradually increasing forcing and some low-level warm air
advection ongoing across the area. However, the main focus for
widespread/organized convection is expected to be activity
moving in from MI/IN late in the day into the evening. Have
likely to categorical (60-80%) POPs spreading into Northwest OH
late afternoon/evening, spreading east-southeast into the night.
Lower POPs spread east a bit quicker mid-later afternoon to
account for any development ahead of the main MCS/line.

We`ll see a drying trend overnight as the shortwave and
convection exit to the east-southeast. However, leave some lower
chances (generally 20-30%) in the forecast through the night to
account for the cold front approaching from the north-
northwest. Higher POPs through the night are found over and near
Lake Erie into Northeast OH and Northwest PA as the front
pushes over the lake, where the warm waters of the lake may
assist in maintaining a local max in instability overnight.

Conditions are somewhat supportive of both a severe weather and
locally heavy rainfall/flash flood threat Saturday afternoon
and evening, reflected by dueling Slight Risks from the SPC and
WPC for severe weather and excessive rainfall respectively. In
terms of severe weather, moderate instability (but skinny
provides owing to very weak mid-level lapse rates), fairly
mixed low-levels, modest to moderate DCAPE of 700-1000 J/KG,
and marginal shear (deep-layer shear of 25-35kt, with weak
low-level shear and storm relative helicity) support loosely
organized convection with potential for wet microbursts. There
is just enough deep-layer shear for rotating updrafts, so don`t
want to entirely rule out isolated large hail and perhaps a
tornado, though overall feel this is a somewhat lower-end severe
threat with damaging winds being the most likely hazard across
the board. The Slight Risk of severe weather feels most
appropriate across Northwest and Central OH, with lower
confidence farther east/northeast. Precipitable water values of
1.70-1.90" are above seasonal averages, though quite not as
high as what we enjoyed earlier this week. Deep warm cloud
depths and relatively skinny instability profiles suggest
potential for torrential rates with storms. Storms are expected
to move at 20-30kt, though there are some hints at repeated
storms across parts of Northwest and Central OH during the late
afternoon/early evening. That could lead to some localized 2-3"+
totals and an isolated flash flood concern, though overall
confidence in these types of totals (both location and
magnitude) is on the lower side.

Highs on Saturday will reach the mid to upper 80s, with peak
heat index values in the low to mid 90s across most of our Ohio
counties (80s into PA). Lows Saturday night will generally
range from the upper 60s to lower 70s.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
The cold front is expected to be draped from Northwest OH across
southern Lake Erie early Sunday and will sag south-southeast
across the area through early evening. With very little large
scale forcing or jet support, have a gradual increase to 40-50%
type POPs from north to south across the area Sunday afternoon
to account for isolated to scattered shower/storm potential. If
anything, these POPs may have a bit of room to trend down, and
the current lack of any outlooks for excessive rainfall or
severe weather seems reasonable given minimal forcing. High
pressure builds in for Sunday night and the start of the week,
bringing cooler and quieter conditions with much more
comfortable dew points.

Highs on Sunday will generally reach the low to mid 80s, warmer
to the south. Lows Sunday night will be noticeably cooler,
ranging from the upper 50s to mid 60s for most. Highs on Monday
will generally reach the upper 70s and lower 80s, with another
pleasant night Monday night with many inland locales dipping
into the 50s. The northeastern edge of a heat dome will begin
spreading towards the local area Monday night, so will need to
watch for remnant convection to spread in from the northwest.
Overall confidence is low and the forecast currently is dry.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
A heat dome centered over the mid-Mississippi Valley will flex
its muscles through Thursday, before enough troughing builds
into New England to shift the heat back a bit farther to the
southwest to end the week. The main focus for the long term
period will be a combination of heat and convection.

In terms of convective potential, low potential for remnant
convection to spill in from the northwest on the periphery of
the building heat ridge persists through Tuesday night. However,
confidence is low and POPs are generally 20% or less, allowing
the forecast to read as dry (20% POPs are "silent" in the
extended). A warm front lifts through on Wednesday, which may
bringing with it somewhat increased convective potential.
However, rising mid-level heights and generally minimal model
QPF lead to low confidence, so again only have "silent" 20%
POPs for Wednesday. Greater potential is evident Thursday into
Friday as troughing begins building into New England, pushing
the westerlies south and closer to the area and allowing a cold
front to approach. Confidence in timing and coverage of any
convection isn`t high that far out, so have some broad-brushed
30-50% (chance) POPs both Thursday and Friday. Given the hot and
humid airmass am not expected a shortage of instability across
the region, so will need to keep an eye on severe weather
potential, especially Thursday and Friday afternoons.

Temperatures begin climbing towards the mid and upper 80s on
Tuesday, though dew points will remain reasonable. Dew points
climb towards and likely over 70F at times starting Wednesday
and until the cold front sags through towards the end of the
week. 850mb temperatures near 20C Wednesday through Friday
support highs in the low to perhaps mid 90s each day, with the
warm dew points suggesting overnight lows will stay in the 70s,
particularly Wednesday and Thursday nights. The potential exists
for at least parts of the area to reach Heat Advisory criteria
(heat index of 100-104F for two or more hours) each day
Wednesday through Friday, with lower potential to reach Warning
criteria (heat index of 105F+ for two or more hours). The
airmass appears quite moisture-rich, so do not expect a mixing
out of dew points to save us from ugly heat index values as much
as sometimes happens. However, convective potential does add a
wrench to the high temperature forecast. The main message is
that another round of hot, humid weather is distinctly possible
Wednesday through Friday of next week, though that considerable
uncertainty exists regarding the specifics. Stay tuned.

&&

.AVIATION /00Z Saturday THROUGH Wednesday/...
Clouds near KMFD and KCAK will gradually erode over the next
couple of hours allowing mainly clear skies to develop. This
combined with light winds, wet ground from today`s showers, and
small temp/dew point depressions overnight will lead to fairly
widespread fog. Continued to add fog more aggressively at all of
the inland terminals late tonight and early Saturday morning
(KFDY, KMFD, KCAK, and KYNG). Periods of 1/4 mile visibilities
are possible, but kept at 1/2 mile for now. Some fog is possible
at KTOL, KCLE, and KERI, but much less likely. Best chance for
some MVFR visibilities is at KTOL.

Fog will dissipate by mid morning Saturday allowing for VFR to
prevail, however, an approaching cold front will combine with
building heat and humidity in the afternoon to generate
scattered thunderstorms. The best potential is from KTOL and
KFDY southeast through KMFD and KCAK in the 20-00Z timeframe,
but any site could see at least a few showers late Saturday
afternoon and evening. Brief periods of MVFR/IFR are likely
with passing showers/storms.

Light and variable winds tonight will turn SW at 5-10 knots by
mid morning Saturday.

Outlook...Non-VFR possible with lingering showers and storms
Sunday. Low non-VFR chances for Monday through Wednesday with
isolated shower/storm chances.

&&

.MARINE...
The lake remains between high pressure to the north and a stationary
boundary to the south and north to northeast flow will continue on
the lake through tonight. The front will lift north as a warm front
on Saturday and allow for south to southwest flow to develop with
some southwest winds of 15 kts or so with the long fetch of the lake
in play. A cold front will cross the lake Saturday night into Sunday
and north to northwest flow will take over with some 1 to 3 ft waves
building by Sunday afternoon and evening. High pressure will arrive
again for Monday and Tuesday and north to northeast flow will become
favored again. High pressure will pass to the east on Tuesday night
and a warm front will lift north across the lake for Wednesday,
allowing for offshore flow to return.

&&

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

&&

$$

SYNOPSIS...Sullivan
NEAR TERM...Sullivan
SHORT TERM...Sullivan
LONG TERM...Sullivan
AVIATION...Garuckas
MARINE...Sefcovic