045
FXUS61 KCLE 011137
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
737 AM EDT Tue Sep 1 2026

.WHAT HAS CHANGED...
Forecast remains on track with Advisory level heat indices for
northern and western Ohio and severe weather potential for
northeastern Ohio and northwestern Pennsylvania.

&&

.KEY MESSAGES...
1) Hot and humid conditions are expected over the next few days with
heat indices approaching the low 100s. Little relief is expected
overnight with lows in the low to mid 70s.

2) There is potential for multiple rounds of thunderstorms today
through Friday bringing with it the potential for severe weather and
heavy rain.

&&

.DISCUSSION...
KEY MESSAGE 1...
The upper level ridge continues to build across the southeastern
CONUS allowing for temperatures and humidity to build across the
Great Lakes region through mid week. Low level flow will generally
be out of the west to southwest into Friday morning that will be the
main driver to advect in the warmer and moist air mass from the
south. 850mb temperatures will begin to warm today to around 20-22C
across the region and persist through Thursday. The warmer side of
those temperatures will be across western Ohio with temperatures a
few degrees cooler to the east. Regardless, high temperatures are
expected to rise into the upper 80s to low 90s today then with more
widespread 90s on Wednesday. Dew points will also climb into the
upper 60s to low 70s. This will push heat indices up to the upper
90s to low 100s with the higher end out west where the current heat
advisory is issued. Additionally, there will be little relief
overnight as lows will only drop down into the mid to low 70s. The
advisory is currently valid starting this afternoon through
Wednesday evening. As with normal summer heat, take precautions when
outdoors and limit strenuous activities during peak heating periods.

There is some uncertainty with how warm the eastern Ohio and
northwestern Pennsylvania will get as rounds of precipitation is
expected through Thursday. This will generally keep temperatures
"down" a bit with the precipitation and consistent cloud coverage.
Though, there maybe enough breaks in the precipitation to allow for
temperatures to rise enough for heat indices to reach the upper 90s.
Will have to watch how each system develops to see if an eastward
expansion of the advisory will be necessary over the next couple of
days. For Thursday, a low pressure system will be moving to the
north, and will sweep a cold front through the region that day.
There should be enough widespread precipitation during the day to
keep temperatures down. The upper level ridge will begin to weaken
across the region and temperatures will fall to be more seasonal
this weekend.

KEY MESSAGE 2...
Along the upper level ridge, a series of shortwaves are expected to
move through the Great Lakes region beginning today through Thursday
resulting in rounds of unsettled weather. A warm and moist air mass
will be in place across the region with a large surface high to the
south. Ample instability of around 2000 MLCAPE will be in place for
much of the week with bulk shear vectors of around 35-40 knots.
PWATs will also be elevated during this time period at 1.5-2.0", so
any thunderstorms that move through will have the threat for heavy
rain as well.

The first of the shortwaves are expected to move into the region
late tonight into early Wednesday morning. There`s plenty of
uncertainty regarding the timing and placement of thunderstorms as
most CAMs disagree with each other. Any storms should follow the
instability gradient which will be situated across northeastern
Ohio, though how far west or east it sets up depends on if any
precipitation forms today along the lake shore and limits the
instability or if there is no development today and it builds east
further. Timing is also an issue as some models have the feature
moving into northeastern Ohio by 6Z Wednesday morning whereas other
are a few hours later. Once the feature gets going up stream, there
will be a better idea of the timing and placement as it moves into
the region. There should be enough in place though that if storms do
form, the would be a damaging wind threat with a secondary threat of
large hail.

There will be a break in the precipitation after this feature moves
late Wednesday morning into the afternoon. Confidence is low, but
some thunderstorms are possible Wednesday afternoon into the evening
developing off a lake breeze or outflows from the mornings storms.
Though the majority should remain dry throughout the day. The next
round of thunderstorms are expected later Wednesday night into
Thursday morning. A low pressure system will be moving north of the
Great Lakes Wednesday night into Thursday and will sweep a cold
front through the region on Thursday. The timing of the front is
still fairly uncertain as it has shifted over the past few model
runs and varies between models as well. If the front slows, then
there may be enough time Thursday morning into the mid day to allow
for a greater severe weather threat. Though, if it is on the quicker
side, then the severe threat may be lower. Will need to monitor how
this develops with the convection earlier in the day and timing of
the front.

For the remainder of Thursday into Friday, showers and thunderstorms
are likely though should be more widespread with the front and with
the surface high to the south retreating. Additionally, another
shortwave is possible late Thursday into Friday that will provide
enough support to keep scattered showers and thunderstorms around
the region into overnight Friday. The weekend forecast currently is
trending dry as Canadian high pressure builds southward over the
region.

&&

.AVIATION /12Z Tuesday THROUGH Saturday/...
A pronounced heat dome will remain in place across the region
today, with ridging/northwest flow aloft. This will allow
scattered to broken mid and high cloud to spill over the top of
the ridge, with occasional isolated showers possible. Light
southwest winds less than 10 knots this morning will become
breezy, with gusts 15-20 knots by mid-day. Hot and humid
conditions will continue.

Outlook...Several rounds of thunderstorms are possible across
Northeast Ohio and Northwest Pennsylvania late Tuesday through
Wednesday night, with a better chance at showers and storms
elsewhere in the area Thursday and Thursday night. A few storms
are expected to be severe with strong winds and large hail. Dry
weather returns Friday and Saturday, with light winds and
cooler temperatures. Occasional non-VFR conditions are expected.

&&

.MARINE...
Broad southwest flow is expected to continue as a stationary
front parks northeast of Lake Erie, with high pressure
entrenched to the south. This pattern will persist through
Wednesday before a cold front moves south across the lake on
Thursday and Friday. Winds could briefly gust to 20 knots with
frontal passage, though small craft advisories are not expected
at this time. Unsettled conditions with multiple rounds of
thunderstorms are expected through Friday, though exact timing
and location of thunderstorms is uncertain at this point. Any
thunderstorms that do occur could become severe, with winds > 34
knots and hail > 0.75".

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Heat Advisory from 2 PM this afternoon to 8 PM EDT Wednesday
     for OHZ003-006>011-017>021-027>031-036-037-047.
PA...None.
MARINE...None.

&&

$$

DISCUSSION...23
AVIATION...27
MARINE...27