983
FXUS61 KCLE 272008
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
408 PM EDT Mon Jul 27 2026

.WHAT HAS CHANGED...
The most organized severe storms have trended mainly west of our
area this evening, but showers and thunderstorms with at least some
severe potential will impact the area at times this evening and
tonight.

&&

.KEY MESSAGES...
1) Showers and thunderstorms will first move into the area between 5
and 8 PM. A few could be severe with damaging winds and heavy rain
the main hazards, but the storms with the greatest severity and
organization should stay west of the area.

2) Additional showers and thunderstorms with lower severe potential
will accompany a cold front overnight.

3) A few lingering showers in NE Ohio and NW PA Tuesday and
Wednesday, but otherwise drier, much cooler, and less humid through
the end of the week

&&

.DISCUSSION...
KEY MESSAGE 1...The forecast continues to be very challenging and
low confidence this evening and tonight in terms of how upstream
convection will evolve and impact our region. Two complexes of
thunderstorms are currently ongoing. The largest and most
organized of the two complexes (MCS`s) is currently propagating
S to SE across eastern Wisconsin, Lake Michigan, western Lower
Michigan, northern Illinois, and NW Indiana. This MCS has
produced widespread significant wind damage and multiple
tornadoes but will continue to make a hard right turn to the S
as it follows the eastern periphery of the thermal ridge, where
a very impressive theta e/instability gradient is draped from N
to S along a quasi-stationary front. This will allow this
MCS to largely miss our area to the west this evening, but the
eastern edge of it may clip the I-75 corridor in the roughly
21-00Z (5 to 8 PM) timeframe with gusty winds and heavy
rainfall.

The second and smaller of the two MCS`s is located
over southern Lake Huron and southern Ontario Province. This MCS
is being more directly forced by the strong mid/upper shortwave trough
that is seen on water vapor imagery digging into the northern
Great Lakes this afternoon. As this shortwave dives through the
central Great Lakes this evening, the left exit of a 115-120
knot H3 jet streak will generate strong synoptic forcing to
sustain this MCS, as well as strengthen a surface low that will
move SE into southern Ontario tonight. Despite lower
instability across northern Ohio and NW PA (2000 MLCAPE)
compared to the extreme instability feeding the larger Lake
Michigan MCS, the combination of the jet support and surface low
should maintain this Lake Huron convection into our area.
Current trajectories time this MCS to reach NE Ohio and NW PA in
the 22 to 23Z (6 to 7 PM) timeframe. The aforementioned
sufficient MLCAPE combined with 40-50 knots of effective deep
layer bulk shear oriented perpendicular to the convection will
support at least scattered severe winds, especially as the
boundary layer continues to warm late this afternoon, with DCAPE
increasing to over 1000 J/Kg. Even in the absence of severe
weather, most areas will see some rain and thunder with this
activity.

KEY MESSAGE 2...
After a lull early tonight, additional showers and
thunderstorms are expected ahead of the cold front as the
mid/upper jet support moves overhead tied to the shortwave
crossing the central Great Lakes. The convection this evening
should overturn the atmosphere and effectively use much of the
instability, but the aforementioned left exit region dynamics
will encourage strong forcing ahead of the cold front to get the
additional convection going overnight. This convection should
generally not be severe given the lower instability, but gusty
winds and locally heavy rainfall will be possible. Maintained
high POPS overnight until the cold front clears the area.

KEY MESSAGE 3...
The mid/upper shortwave will become vertically stacked with the
surface low and close off over upstate New York by Tuesday
evening. This along with the parent longwave mid/upper trough
becoming negatively tilted across the eastern CONUS by Wednesday
and Thursday will allow the system to evolve into a coastal low
near Long Island. The result for northern Ohio and NW PA will
be broad cyclonic flow and associated cold air advection Tuesday
through Thursday. A secondary front or surface trough dropping
through the region Tuesday afternoon combined with the
deepening trough aloft will generate scattered showers, mainly
in interior NE Ohio and NW PA, so increased POPS Tuesday
afternoon. Otherwise, wraparound moisture in the cyclonic flow
combined with cold air advection across the warm lakes will lead
to periodic lake enhanced showers over far NE Ohio and NW PA
through Wednesday before Canadian high pressure finally builds
into the central Great Lakes and Ohio Valley late Wednesday and
persists through the end of the week, supporting pleasantly cool
and dry conditions areawide. Low temperatures will drop into
the 50s both Thursday and Friday mornings allowing the air
conditioners to get a break before gradual warming over the
weekend.

&&

.AVIATION /18Z Monday THROUGH Saturday/...
Two upstream areas of convection are being monitored for TAF
impacts for late this afternoon through this evening. The first
is currently near Chicago and the second is over Lake Huron. If
these areas of convection maintain their current
trajectories/strength, they will likely make it into the area by
around 21-22Z. Overall, confidence in rain occurring at any
given TAF site is high through this evening, but coverage of
thunderstorms is low so have maintained prevailing showers with
VCTS/PROB30 groups for thunderstorms. Amendments will likely be
needed as the upstream convection becomes closer. Either way,
any storms that move over terminals this evening could produce
non-VFR conditions and erratic and gusty winds. Additional
showers and storms are possible into the overnight hours with
rain chances decreasing early Tuesday morning. MVFR ceilings
will develop late tonight/early Tuesday morning with conditions
likely improving from the west towards the end of the TAF
period.

Winds will be out of the southwest at 6 to 12 knots with gusts
to 20 knots through tonight before becoming northwest at 8 to
14 knots with gusts to 20 to 25 knots at around 12Z Tuesday.

Outlook...Non-VFR may persist in lower ceilings and scattered
showers through Wednesday, primarily across Northeast Ohio and
Northwest Pennsylvania. Non-VFR possible in scattered showers
and thunderstorms on Saturday.

&&

.MARINE...
Scattered thunderstorms are likely this
evening and tonight and winds/waves will likely be higher in any
storms. Southwest winds will shift to the northwest and
increase to 15 to 25 knots early Tuesday morning through much of
Wednesday. The highest winds/waves will be in the nearshore and
open waters of the central basin. Small Craft Advisories and
Beach Hazards Statements have been issued from the Islands to
Conneaut Tuesday morning through late Wednesday evening and from
Conneaut to Ripley NY from Tuesday afternoon through Wednesday
afternoon. Small Craft conditions may briefly occur west of the
Islands early Tuesday morning so will need to monitor that area
for a brief expansion.

Northwest winds to 10 to 15 knots will continue through Thursday
with more light and variable flow and daily lake breezes developing
Friday into the weekend.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Beach Hazards Statement from Tuesday morning through late
     Wednesday night for OHZ009>012-089.
PA...Beach Hazards Statement from Tuesday afternoon through
     Wednesday afternoon for PAZ001.
MARINE...Small Craft Advisory from 8 AM Tuesday to 2 AM EDT Thursday
     for LEZ144>148.
     Small Craft Advisory from 2 PM Tuesday to 4 PM EDT Wednesday
     for LEZ149.

&&

$$

DISCUSSION...Garuckas
AVIATION...15
MARINE...15