-- Discussion containing changed information from previous version are highlighted. --
488
FXUS61 KCLE 040521
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
121 AM EDT Tue Jun 4 2024

.SYNOPSIS...
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A warm front lifts north across the region today and tonight
followed by a cold front on Wednesday night. A trough builds in
on Thursday which will linger across the area through the
weekend.
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&&

.NEAR TERM /THROUGH TONIGHT/...
900 pm update... There were no adjustments made to the ongoing
near term forecast as this time.

Previous discussion...
Fog and low clouds have finally dissipated across NE Ohio and
NW PA, although weak onshore flow from a lake breeze is bringing
lower visibilites and haze onshore east of Cleveland at times
since patchy fog and haze continues over Lake Erie. Lakeshore
areas from KCLE to KERI will see occasional drops in visibility
to 3 to 5 miles this evening until the land breeze starts to
kick in after 00 or 01Z, shifting the winds back offshore. One
culprit to the lingering low-level moisture and resultant patchy
fog today appears to be a diffuse warm front stretching
southeastward from Lower Michigan to along the I-70 corridor in
central Ohio. This front appears to have surged northward into
southwestern Lower Michigan this afternoon where SW surface
winds are seen in surface obs from that area through Indiana,
but farther east, the frontal boundary appears to be curved
south of the lower Great Lakes struggling to move northward as
seen by generally light SE surface winds from southeastern Lower
Michigan into northern Ohio. Some moisture pooling near the
boundary and onshore flow near Lake Erie have seemed to keep the
lower clouds and haze in place today, and that will especially
remain the case over the lake tonight as dew point temps will be
close to lake surface temps (low to mid 60s). The front should
finally start to lift north and cross the lake tonight in
response to weak low pressure lifting from the Upper Midwest
this evening into northern Ontario Tuesday. This will allow the
entire region to gradually get into the warm sector, so most
areas will avoid fog tonight outside of immediate lakeshore
areas and parts of interior NE Ohio and NW PA where the boundary
will linger and combine with the nocturnal inversion. Mid/upper
ridging will amplify across the Ohio Valley and Great Lakes
Tuesday as the front quickly surges north in response to a
deeper mid/upper trough diving into the northern Plains. This
will lead to very warm and humid conditions in the warm sector
with strong warm air advection supporting highs in the mid/upper
80s and dew points reaching the mid 60s. Went slightly above
blended guidance for highs Tuesday since most areas will have no
problem warming quickly given lots of sunshine expected. The
gradient should also be strong enough to keep the lake breeze
confined to immediate lakeshore areas east of Cleveland.
Moderate instability is expected for the afternoon, but forecast
soundings suggest enough mid-level capping to keep all areas
dry, so kept PoPs out of the forecast. We`ll just need to watch
the lake breeze boundary to possibly ignite an isolated
thunderstorm.

Chances for showers and thunderstorms will gradually increase in
NW and north central Ohio Tuesday night as the aforementioned
mid/upper trough axis swings into the Upper Midwest and pushes a
strong cold front into the western Great Lakes. With the
stronger forcing not expected to arrive until Wednesday, kept
PoPs at slight chance to chance Tuesday night, so most areas
will stay dry. Lows Tuesday night will stay warm and humid with
65-70 expected in most areas.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Cyclonic SW`erly to W`erly flow aloft over our CWA through Wednesday
night becomes W`erly to NW`erly on Thursday through Thursday night
as a mid/upper-level low develops/wobbles SE`ward from near central
MB to near Georgian Bay. Simultaneously, shortwave disturbances
embedded in the flow aloft traverse our region and a surface trough
impacts northern OH and NW PA. A cold front accompanying one of the
shortwave disturbances is expected to sweep E`ward through our
region Wednesday evening through Thursday morning. Isolated to
scattered and periodic showers/thunderstorms are expected along and
ahead of the cold front due to pre-front isentropic ascent and low-
level convergence/ascent along the front itself. These lifting
mechanisms are expected to coincide with sufficient low-level
moisture and release weak to moderate instability, including
elevated instability. Some storms may be strong to severe Wednesday
afternoon and evening when moderate boundary layer CAPE in the
warm/moist sector should overlap with moderate deep layer bulk
shear. Behind the cold front, isolated/periodic rain showers are
expected during the rest of Thursday through Thursday night due
to moist isentropic ascent preceding shortwave trough axes,
low- level convergence/moist ascent along attendant surface
trough axes, and the presence of potential instability in the
surface to roughly 850 mb layer. Daytime heating of the
relatively-moist boundary layer should yield weak, yet
sufficient mixed layer CAPE for isolated thunderstorm
development Thursday afternoon into early evening.

Low-level WAA and peeks of sunshine should allow Wednesday`s late
afternoon highs to reach the upper 70`s to mid 80`s prior to the
cold front passage. Gradual low-level cold/dry air advection behind
the cold front should contribute to overnight lows reaching the
lower to mid 60`s around daybreak Thursday morning. Late afternoon
highs should reach the 70`s on Thursday and overnight lows should
reach mainly the 50`s around daybreak Friday as colder air continues
to overspread our region.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Cyclonic W`erly to NW`erly flow aloft and embedded shortwave
disturbances continue to affect the Great Lakes and Upper OH Valley
as the aforementioned mid/upper-level low wobbles in vicinity of
central ON province. At the surface, a troughing lingers over/near
our CWA and trough axes accompany the shortwave disturbances. This
pattern will maintain an unusually-cold air mass across our region.
Periodic and isolated to scattered showers/thunderstorms are
expected during the long-term period for very similar reasons noted
in the Thursday through Thursday night portion of the short-term
discussion. The greatest potential/coverage of convection are
expected each afternoon through early evening due to the expectation
of a typical diurnal cycle in boundary layer temperatures and
instability, and self-destructive sunshine. Late afternoon highs
should moderate gradually from the mid 60`s to lower 70`s on Friday
to the 70`s to 80F on Monday. Overnight lows should reach mainly the
50`s Friday night through Sunday night, respectively.

&&

.AVIATION /06Z Tuesday THROUGH Saturday/...
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VFR conditions are observed and are expected to be the
predominant condition through the TAF period. The exception
could be some patchy BR, especially for central and east-central
Ohio, early this morning between 08-12Z. Isolated rain showers
might start moving in from the southwest late tonight, but this
is low confidence. Only added VCSH to KFDY and KCLE.

Winds will be light and variable or from the south tonight under
5 knots. Winds become predominantly out of the south and
strengthen to 5 to 10 knots during the daytime hours today.
Another lake breeze is likely this afternoon, though probably
most make as much inland progress as yesterday.

Outlook...Non-VFR is expected with periods of showers and
thunderstorms Wednesday and Wednesday night. Non-VFR will be
possible with scattered rain showers and isolated afternoon
thunderstorms Thursday through Saturday.
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&&

.MARINE...
Variable winds around 5 to 15 knots are expected through Tuesday
as the western flank of a ridge affects Lake Erie. These winds
will have on onshore component through this early evening and
again late Tuesday morning through early evening due to lake
breeze development. SE`erly winds around 5 to 15 knots veer
gradually to S`erly Tuesday night into Wednesday as a warm front
drifts N`ward across the lake. A cold front is then poised to
sweep E`ward across Lake Erie Wednesday evening through Thursday
morning. The cold front passage will cause S`erly to SW`erly
winds around 5 to 15 knots to veer to W`erly. Behind the cold
front, a trough is expected to linger over the Lake Erie region
through Saturday and be accompanied by WSW`erly to NW`erly winds
around 10 to nearly 20 knots. Waves are expected to be mainly 3
feet or less, but occasional 4 footers are expected, especially
east of The Islands, on Friday through Saturday.

Of note, patchy advection fog is expected to linger over Lake
Erie, especially east of The Islands, for the time being.
Mesoscale subsidence associated with a stronger lake breeze
circulation over/near Lake Erie should allow the fog to
dissipate by the early afternoon hours of Tuesday.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
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OH...Air Quality Alert until midnight EDT tonight for OHZ010>014-
     020>022-089.
PA...None.
NY...None.
MARINE...None.
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&&

$$

SYNOPSIS...Garuckas
NEAR TERM...Garuckas/Griffin
SHORT TERM...Jaszka
LONG TERM...Jaszka
AVIATION...Saunders
MARINE...Jaszka