Severe Thunderstorm Warning 165, NWS Cleveland, OH

Area Forecast Discussion
National Weather Service Cleveland OH
349 PM EDT Tue Oct 21 2025

.SYNOPSIS...
A trough moves east across the area this evening, with another trough
crossing the area Wednesday night into early Thursday. High pressure
builds into the Ohio Valley and moves across the area this weekend. A
weak disturbance moves through the Ohio Valley Monday and Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
A large closed low is moving east into the Great Lakes. A sharp
surface trough (really more of a secondary cold front) will move east
across the area through about midnight...it is near the Ohio/Indiana
border as of 3 PM. With assistance from the left-exit quadrant of a
jet streak rotating around the closed low and an embedded vort max, a
broken band of low-topped convective showers and some storms will
accompany the surface trough east across our forecast area. Activity
should exit to the east with the trough by midnight, with thunder
potentially gradually decreasing after 9 or 10 PM. The main focus
overnight will then turn towards a developing band of robust lake
effect rain, which may initially graze the eastern lakeshore as it
takes shape around midnight before lifting offshore and into western
New York overnight amid deep-layer west-southwest flow. It will be a
mostly cloudy but mainly dry rest of the night elsewhere, though as
various spokes of moisture and weak mid-level vorticity rotate around
the larger closed low a few passing sprinkles or light showers
continue to remain possible anywhere. Forecast rain amounts are
generally on either side of 0.10" with this evening's low-topped
convection, with amounts with any overnight activity very light. Lows
tonight will range from the upper 30s to mid 40s, with brisk west-
southwest winds gusting 20-30 MPH, driving "wind chills" into the 30s.

The SPC has placed a Marginal Risk for severe weather (level 1 of 5)
across a good portion of our area this evening. Relatively steep low
to mid-level lapse rates beneath the cold core aloft and deep low-
level inverted-v soundings suggest efficient momentum transfer, with
sub-cloud evaporational cooling supporting cold pool development with
any organized convection. With moderate flow aloft, it won't take a
ton of convective enhancement to get some strong (40MPH+) to perhaps
locally severe (58MPH+) wind gusts with this convection, along with
small/soft hail. Some convective allowing models suggest the
convection briefly congealing into a couple of more solid line
segments between about 5-8 PM, which would be the greatest potential
for locally severe wind gusts. So, will monitor this activity east
across the area for Special Wx Statements and perhaps a warning or two
through the evening. Expect the bite of any wind gusts (and any
severe threat) with the convection to start decreasing after 8 PM, as
nocturnal stabilization perhaps adds just enough of a near-surface
inversion to limit momentum transfer to the surface.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
The Great Lakes closed low will gradually shift east-northeast towards
Quebec and New England through Thursday night, with occasional surface
troughs and embedded weak shortwaves continuing to rotate around the
larger closed low. This will continue chilly, breezy, and showery
weather. Shower chances outside of the lake effect will largely be
tied to any surface trough and shortwave passages, with some
enhancement from Lake Michigan into Northwest Ohio at times. The main
focus for heavier precipitation will be with the lake effect off of
Lake Erie into the primary snowbelt region.

The lake effect will be offshore and into western New York to start
the day Wednesday. A weak shortwave and surface trough move across the
area late Wednesday morning and early afternoon, bringing an uptick in
isolated to scattered showers elsewhere and pushing the lake effect
band southeast towards the shoreline between Lake County OH and Erie
County PA. Lake effect will struggle to really push inland late
Wednesday afternoon through much of Wednesday night (despite what some
convective allowing models show), given flow quickly wanting to back
southwest ahead of the next surface trough and shortwave, which will
approach Wednesday night and cross early Thursday morning. This idea
is further supported by the warmth of the lake, arguing for a strong
lake aggregate trough, a feature that notoriously causes strong,
single lake effect bands to remain tied closer to the shoreline than
modeled. For this forecast, heavily favored the RGEM for the general
placement of the lake effect band. The trough passage early Thursday
may bring a few sprinkles or showers anywhere, especially downwind of
Lake Michigan, and will veer the mean flow more substantially, pushing
the main lake effect band closer to the Cleveland area and farther
inland across the primary snowbelt. The lake effect will likely
transition from an organized single band to more disorganized multi-
bands at some point on Thursday as the mean flow over the lake goes
closer to northwest. From there, lake effect will continue to ebb and
flow in general west-northwest flow through Thursday night as any
addition troughs rotate through, with guidance hinting at another
trough Thursday evening. Passing sprinkle/shower chances diminish
outside of the lake effect Thursday night as the closed low gradually
exits, allowing high pressure to approach from the southwest.

Over lake water temperatures of 17-18C, 500mb temperatures bottoming
out around -26C, 700mb around -12C, and 850mb around -2C suggest very
strong and deep instability, which is validated by raw model forecast
soundings depicting CAPE extending to 20k feet or higher at times,
which is enough instability for charge separation/lightning and small
hail/graupel in the more intense lake effect band when it's cranking.
The thermodynamics are most favorable through Thursday morning before
temperatures aloft slowly start warming. There will be abundant
synoptic moisture into Thursday within the influence of the large
closed-low, with fairly minimal amounts of wind shear except for brief
periods of stronger shear near the trough passages. All this to say
that lake effect will be intense through Thursday morning, with heavy
rain, thunder/lightning, and some frozen hydrometeors at times near
the lake. A shorter fetch, somewhat more shear, and gradually
decreasing instability will lead to intensity gradually decreasing
Thursday afternoon, though not nearly to the point where it stops.

The main focus for heavy QPF is late Wednesday through early
Thursday, when activity may persist along the general I-90 corridor
between Lake County and Erie County PA while intense. The forecast
maintains 1-3" of rain between Lake, far northeast Cuyahoga, and
northern Geauga Counties northeast across northern Ashtabula and much
of Erie Counties through Thursday night. Some hi-res models suggest
locally up to 4-5" of rain is possible if the band is especially
intense/persistent in one spot, though those gaudier totals will be
more feasible just offshore of Erie County PA than on land. Still,
will monitor for localized flooding concerns if a period of focused
and persistent heavy rain can materialize. Rain amounts with the lake
effect dramatically drop off towards a CLE-YNG line, which is about as
far southwest as the organized band may get Thursday morning before
breaking up into multi-bands. Locations outside of the lake effect
should see less than 0.25" of rain during the short term period.

Highs both days will be stuck well down into the 50s, with the higher
terrain of far Northeast OH and Northwest PA in the 40s. Overnight
lows will range from the mid 30s to mid 40s, warmest in the primary
snowbelt and downwind of Lake Erie. Some frost is possible across our
western and southwestern counties Thursday night, as approaching high
pressure brings a somewhat weaker pressure gradient and clearer skies.
Wind gusts of 30-40 MPH are likely Wednesday afternoon across the area
in association with the expected trough passage.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
High pressure gradually builds in for Friday and Saturday. Lingering
lake effect continues Friday and perhaps even into Saturday across far
Northeast Ohio and Northwest PA, though will not be particularly
significant by then. Guidance has been gradually trended towards
stronger high pressure this weekend, which would keep a weak system
moving across the south out of our picture and lead to dry weather.
Some low POPs linger in the forecast for Sunday and Monday for now,
but are trending down. Temperatures gradually moderate to near or
slightly warmer than average to start next week. Some additional
frost/freeze concerns are possible Friday-Saturday nights.

&&

.AVIATION /18Z Tuesday THROUGH Sunday/...
VFR will continue this afternoon, but showers and some embedded
thunderstorms will spread across the region from west to east
this evening ahead of the next cold front. This activity will
bring gusty winds of 30-40 knots and brief periods of MVFR or
lower. Timing looks to bring this line into KTOL and KFDY
after 20Z, KMFD, KCLE, and KCAK by 22 or 23Z, and through the
OH/PA border affecting KYNG and KERI by 23 to 00Z. Drier air
will move back in behind the line of showers/storms allowing for
a return to mainly VFR tonight, but a lake-effect pattern will
quickly set up as cold air deepens across Lake Erie and winds
become well-aligned from the west-southwest. This will lead to
lake-effect rain showers affecting KERI and the adjacent
lakeshore of extreme NE Ohio and NW PA at times late tonight
and Wednesday bringing periods of MVFR or lower. Yet another
cold front/trough could also bring a burst of rain showers to a
larger area of NE Ohio and NW PA mid to late Wednesday morning.
Periods of MVFR or lower will accompany any of these showers
too. Any terminal could see isolated showers during the day
Wednesday, but as mentioned, NE Ohio and NW PA will have the
best potential.

WSW winds of 10-15 knots will gust to 20-25 knots at times
through tonight before increasing to 15-25 knots with gusts of
30-35 knots late Wednesday morning into the afternoon.

Outlook...Periods of non-VFR are expected through Saturday as
scattered to widespread rain showers and isolated thunderstorms
accompany disturbances. In addition, localized lake-effect rain
showers and perhaps occasional lake-effect thunderstorms will
impact the Snowbelt of NE OH/NW PA and vicinity and result in
periodic non-VFR conditions.

&&

.MARINE...
A closed upper level low pinwheeling over the northern Great Lakes
tonight and Wednesday will gradually lift across Quebec Thursday and
Friday. This will support a period of active marine conditions on
Lake Erie for the rest of the week as a series of reinforcing
troughs rotate through the region, keeping gusty west and eventually
northwest winds in place as well as lake-effect showers and
waterspouts.

WSW winds will increase to 20-30 knots tonight behind a secondary
cold front/trough that crosses this evening. These WSW winds will
further increase to 35 knots gales on much of the lake Wednesday,
with gusts up to 45 knots during the afternoon. This will build wave
heights to 7-10 feet on the central and eastern basins tonight and 9-
14 feet Wednesday. Upgraded to Gale Warnings from the Islands to
Ripley, NY from 12Z Wednesday through 03Z Thursday for these high
winds and waves, with Small Craft Advisories continuing on the far
western basin. Additionally, the favorable WSW direction will cause
water levels to drop below the critical mark of -1 inches above low
water datum tonight through Wednesday, so issued a Low Water
Advisory. Winds will gradually lessen Wednesday night, but W winds
of 15-25 knots are likely to continue through at least Thursday
night and possibly into Friday while turning more NW by then, so
Small Craft headlines will eventually be extended through the end of
the week. High pressure will finally build across the Great Lakes
over the weekend supporting much calmer conditions.

Waterspouts will accompany lake-effect rain bands tonight into
Friday, so Special Marine Warnings and statements will be issued as
needed for this activity.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Small Craft Advisory until 4 AM EDT Thursday for LEZ142>144.
     Small Craft Advisory until 11 AM EDT Wednesday for LEZ145>148.
     Gale Watch from Wednesday morning through Wednesday evening
     for LEZ145>148-165>168.
     Small Craft Advisory until 10 AM EDT Friday for LEZ149.

&&

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

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