CLE issues Area Forecast Discussion (AFD) at Jul 24, 3:36 AM EDT070
FXUS61 KCLE 240736
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
336 AM EDT Thu Jul 24 2025
.SYNOPSIS...
Northern Ohio and northwest Pennsylvania remain along the
northwestern flank of a high pressure ridge for the time being. A
cold front should sweep generally southward through our region on
Friday and stall in vicinity of central Ohio by Friday evening.
The front should then waver across our region on Saturday and then
sweep generally southward through our area as a cold front once
again on Sunday as lows of varying intensity move generally
eastward along the front.
&&
.NEAR TERM /THROUGH FRIDAY/...
Aloft, a ridge focused over the interior southeast U.S. and
southern Great Plains becomes "flattened" today through Friday
as shortwave disturbances embedded in W'erly flow impact the
north- central U.S., Great Lakes region, including our CWA, and
the northeast U.S. At the surface, our region remains along the
northwestern flank of the Bermuda-Azores subtropical ridge for
the time being as a cold front approaches our area from northern
and eventually central portions of the Great Lakes. The
anticyclonic circulation of the ridge will continue to result in
low-level warm/moist air advection from the Gulf. Accordingly,
our surface dew points are expected to rise to the lower to mid
70's by this late morning/early afternoon and then remain in
that range through tonight, ahead of the front. Between about
daybreak and nightfall on Friday, the weak cold front is
expected to move SSE'ward through our region and result in
limited air mass change.
Daytime heating amidst abundant sunshine and the aforementioned
low-level WAA will allow today's late afternoon highs to reach
the upper 80's to lower 90's in NW PA and mainly the lower to
mid 90's in northern OH. The combination of heat and high
humidity will allow maximum heat indices to reach 95F to around
100F in NW PA and mainly 100F to around 105F in northern OH late
this afternoon and early evening. Accordingly, a Heat Advisory
is in effect from 11 AM to 8 PM EDT today for all of our
northern OH counties. Refrained from expanding the advisory to
Erie and Crawford Counties in PA since maximum heat indices of
100F should be localized in that area. Sufficient daytime
heating of land surrounding ~77F Lake Erie and a weak synoptic
MSLP gradient are still expected to allow a lake breeze to
develop along and within several miles of the lakeshore in
northeastern Cuyahoga County through Erie County, PA. However,
the lake breeze is expected to provide little relief from the
heat and high humidity. Increasing cloud cover should contribute
to lows reaching the upper 60's to mid 70's around daybreak
Friday and cooler highs in the 80's late Friday afternoon.
Stabilizing subsidence accompanying the above-mentioned ridge
should allow fair weather to persist in our CWA through sunset
this evening. Later this evening through Friday, periods of
scattered multicell showers and thunderstorms are expected to
impact our region as low-level convergence/moist ascent along
the synoptic cold front and downshear outflow boundaries release
weak to moderate boundary layer CAPE amidst moderate deep layer
bulk shear. Despite boundary layer stabilization via nocturnal
cooling and resulting weakening of low-level lapse rates,
forecast model soundings suggest relatively-dry mid-level air
will support DCAPE near 500-1000 J/kg and the potential for
isolated straight-line convective wind damage tonight into
Friday morning. Later on Friday, isolated straight-line
convective wind damage remains possible, especially farther
south in our CWA, as the warm/moist sector boundary layer
destabilizes via peeks of sunshine, diurnal convective mixing of
the boundary layer causes low-level lapse rates to steepen, and
DCAPE remains at least roughly 500-1000 J/kg. Periods of heavy
rain are expected due, in part to unusually-high PWAT values in
the warm/moist sector. Due to this factor and the expectation
of training showers/thunderstorms along the front as W'erly
mean mid-level flow exhibits a large component parallel to the
front, localized flash flooding remains a concern tonight
through Friday.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
W'erly flow aloft through Saturday night should become NW'erly
over our region on Sunday through Sunday night as a portion of
the aforementioned ridge aloft amplifies over/near the southern
and central Great Plains due, in part to several consecutive
days of strong daytime heating. Shortwave disturbances embedded
in the flow aloft will continue to affect our region. At the
surface, the weak synoptic front should stall in vicinity of
central Ohio Friday evening and then waver between the OH Valley
and central Great Lakes on Saturday through Saturday night as
multiple weak lows move generally E'ward along the front. The
front should finally sweep generally S'ward through our CWA on
Sunday, following the E'ward passage of a somewhat stronger
frontal low accompanying a stronger shortwave trough aloft.
Behind the front, a weak ridge should build briefly from central
ON before the front sweeps back NE'ward through our CWA
overnight Sunday night as a primary low begins to move
generally E'ward across the northern Great Lakes.
Additional periods of scattered showers and thunderstorms are
expected as weak to moderate instability, including elevated
CAPE, is released by the following: moist isentropic ascent
ahead of the shortwave trough axes; low-level convergence/moist
ascent along the front and associated with the cyclonic
circulations of the frontal lows. Moderate deep-layer bulk shear
should exist over/near our region and allow showers and
thunderstorms to organize into multicells. The aforementioned
instability and vertical wind shear may allow some storms to
become strong to severe, especially during the afternoon and
early evening hours of Saturday and Sunday, when peeks of
sunshine and daytime heating allow the moist boundary layer to
destabilize. South of the front, a warm and very humid air mass
originating over the Gulf will reside in our region and likely
be accompanied by unusually-high PWAT values. Thus, periods of
heavy rain are likely. W'erly mean mid-level flow should exhibit
a large component parallel to the synoptic front and a lake
breeze front that may become established just inland from Lake
Erie during the afternoon and early evening hours of Saturday
from northeastern Cuyahoga County through Erie County, PA. Thus,
training showers/storms may occur along both air mass boundaries
and contribute to localized flash flooding concerns. Fair
weather is still expected Sunday night, when stabilizing
subsidence accompanying the aforementioned surface ridge should
affect our region. Current odds favor fair weather Sunday night,
due to boundary layer stabilization via nocturnal cooling and
stabilizing subsidence accompanying the ridge expected to build
briefly into our area.
Lows mainly in the mid 60's to lower 70's are expected around
daybreak Saturday, Sunday, and Monday. Peeks of sunshine should
allow late afternoon highs to reach the 80's to near 90F on
Saturday and Sunday.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
NW'erly flow aloft and embedded shortwave disturbances should
continue to affect our region on Monday through Wedneday as the
amplified ridge aloft persists over/near the southern and
central Great Plains and a deepening trough aloft shifts from
central to eastern portions of Canada. At the surface, a ridge
should build from the Lower MS Valley on Monday before a cold
front sweeps SE'ward through our CWA Monday night as the
aforementioned primary low moves from the northern Great Lakes
toward the St. Lawrence River Valley. Behind the cold front, a
ridge associated with a somewhat cooler and drier air mass
should build gradually from central Canada through Wednesday.
Periodic isolated to scattered showers and thunderstorms are
possible during the long-term period, due in part to the release
of weak to moderate CAPE, including elevated CAPE, by the
following: moist isentropic ascent preceding the aforementioned
shortwave trough axes; low-level convergence/moist ascent along
subtle surface trough axes expected to accompany the shortwave
disturbances. Late afternoon highs should reach mainly the mid
80's to lower 90's on Monday and Tuesday, and the upper 70's to
mid 80's on Wednesday. Overnight lows should reach mainly the
mid 60's to mid 70's around daybreak on Tuesday and Wednesday.
&&
.AVIATION /06Z Thursday THROUGH Monday/...
Warm sector environment ahead of a cold front that will meander
southeastward towards northwest Ohio after 00Z Friday. Daytime
heating cumulus cloud formation expected after 16Z today around
FL045. Southwest winds 10kts with gusts to 20kts possible,
especially at TOL/FDY, but also carrying gusts further east as
well. POPs work their way into Toledo late in the TAF period,
but too low for prevailing or even VCSH/VCTS for now.
Outlook...Non-VFR possible in showers and thunderstorms Thursday
night, particularly across northwest Ohio. Non-VFR chances will
continue to increase areawide Thursday night into Friday in
scattered to perhaps widespread showers and thunderstorms. Non-
VFR chances may persist on Saturday in Sunday in scattered
showers and thunderstorms. Generally VFR favored for Monday.
&&
.MARINE...
Weak offshore winds today will allow a lake breeze to develop
Cleveland and east with light chop forming in the afternoon. A late
Thursday night/early Friday morning cold front brings northwesterly
winds 10kts and wave heights 1-3ft Friday, easing to less than a
foot Friday night. Variable winds becoming offshore less than 10kts
Saturday will allow for another lake breeze to develop and more
afternoon chop. A Sunday cold front brings winds westerly to west
northwesterly 10-15kts and wave heights 1-3ft. Winds back to
offshore Monday and wave heights a foot or less.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Heat Advisory from 11 AM this morning to 8 PM EDT this evening
for OHZ003-006>014-017>023-027>033-036>038-047-089.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...Jaszka
NEAR TERM...Jaszka
SHORT TERM...Jaszka
LONG TERM...Jaszka
AVIATION...26
MARINE...26
Source:
CLE issues Area Forecast Discussion (AFD) at Jul 24, 3:36 AM EDT---------------
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