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212
FXUS61 KCLE 261045
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
645 AM EDT Sun May 26 2024

.SYNOPSIS...
Low pressure will track northeast from the Mississippi Valley
toward the central Great Lakes today and tonight, lifting a warm
front into the area today followed by a cold front on Monday. A
few disturbances will cross the area Tuesday into Wednesday
before high pressure returns Thursday.

&&

.NEAR TERM /THROUGH MONDAY/...
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630 AM Update...
Dense fog/low stratus have expanded west into southeastern
Cuyahoga County and northern Summit County. Opted to expand the
Dense Fog Advisory to include these zones. Diurnal mixing should
kick in pretty quickly this morning so still think that 10 AM is
more than sufficient for an expiration time. No changes needed
with this update beyond making adjustments to the headline.

Previous Discussion...
Areas of dense fog have developed across interior NW PA and NE
OH, primarily in river valleys and locations that received
rainfall on Saturday. A Dense Fog Advisory is in effect for
inland zones including Geauga and Portage counties east, however
a period of patchy dense fog is possible in Summit, Lake, and
far eastern Cuyahoga counties right around sunrise. The advisory
ends at 10 AM, but it`s likely that most fog is gone by 8 or 9
AM since diurnal mixing will kick in pretty quickly.

The forecast becomes quite challenging later today. A warm
front will lift north into at least the southern half of the
area today as low pressure lifts northeast from the Mississippi
Valley towards the central Great Lakes with a shortwave crosses
the area along the warm front late this afternoon into this
evening. The shortwave will lift a line of showers and
thunderstorms into southwestern zones at around 21Z/5 PM. There
has been quite a shift in guidance in the last 12-24 hours with
most CAMs hinting at a bit more instability across the area and
the better LLJ support over the area this afternoon into early
to mid evening rather than overnight, which could result in an
earlier window for severe weather potential and perhaps slightly
higher chances since convection will be occurring during a more
diurnally favorable period. With that being said, stronger
convection to the south could rob the area of additional
moisture and destabilization will depend on the location of the
warm front when the shortwave crosses the area. If
destabilization does occur, damaging wind gusts will be the
primary threat but can`t rule out large hail in the Slight Risk
area. Instability wanes with the loss of diurnal heating this
evening, so the severe weather risk should diminish as the
storms track northeast. There may be enough helicity/shear
(shear values are ~30 knots) for potential for a few tornadoes
in the western half of the area. If a scenario with higher low
level moisture pans out, heavy rainfall will be possible but the
flooding threat will be low since storms will be quite
progressive.

The line should exit the area shortly before midnight. The next
round of showers and thunderstorms will likely clip the area
overnight into Monday morning as an MCS tracks across the Ohio
Valley and a pre-frontal shortwave ripples across the region.
The nocturnal severe weather risk has shifted south into the
Ohio Valley where the MCS will take advantage of the best LLJ
and instability. Will need to keep an eye on guidance and
mesoscale features throughout the day though, especially if the
afternoon/earlier evening convection does not materialize. Any
precip may less progressive and PWAT values as high as 1.5
inches may result in locally heavy rainfall and a low-end
flooding threat, primarily south of US-30.

The aforementioned low will track northeast across the central
Great Lakes Monday and its cold front will cross the CWA Monday
morning and afternoon. Scattered showers/storms remain likely in
the eastern half of the local area Monday morning and afternoon
and can`t rule out a few stronger storms in far eastern zones
as the front begins to exit during peak heating. By that time,
the best forcing/instability will likely be to the east of the
area so the severe weather threat is low in NW OH/NW PA.

Today`s highs will be in the low to mid 80s with overnight lows
in the 60s. Temps will be a bit cooler Monday and anticipate
maximum temps in the mid 70s.
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&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Shortwave troughs will continue to move along the parent upper level
trough for much of the short term period, resulting in additional
potential for showers and thunderstorms on Tuesday and Wednesday.
Initially on Monday night, a few lingering showers are possible
across the eastern counties as a surface cold front moves east of
the area, but any dry period will be shortly lived as another
shortwave advects energy across the area Tuesday morning. The best
chance of showers and thunderstorms on Tuesday should be downwind of
a northwest flow across Lake Erie, but with diurnally instability
and enough moisture elsewhere, cannot rule out additional showers
and thunderstorms over the remainder of the area through Tuesday
night. On Wednesday, another weak cold front will move southeast
across the area, marking the transition to a dry period for the end
of the week. By Wednesday night, high pressure and an associated
upper level ridge will finally be pushing east and drying out the
area.

High temperatures on Tuesday will climb into the upper 60s to low
70s for much of the area before cooling behind the departing cold
front to only reach into the 60s on Wednesday. Overnight lows will
also gradually cool from the mid to upper 50s on Monday night to the
mid 40s by Wednesday night.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
A dominant upper level ridge and associated surface high pressure
over the central portion of the US will act as the primary moderator
of weather through the long term period. This will allow for at
least a couple dry days, but will also result in temperatures again
climbing to above normal for this time of year with highs reaching
into the upper 70s to low 80s by Saturday. There is a bit of
difference in the timing of the progression of the ridge, but either
way it looks to remain over the area.

&&

.AVIATION /12Z Sunday THROUGH Thursday/...
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Patchy fog and low stratus are producing non-VFR conditions at NE
OH/interior NW PA terminals. Conditions should improve to VFR no
later than 14Z.

A line of showers and thunderstorms will lift northeast into
the area late this afternoon or early this evening (~20-21Z)
and reach NW PA before Midnight. The showers/storms should be
progressive so any non-VFR visibilities should be short-lived at
any given terminal. A few strong gusts to 25 to 35 knots are
possible within thunderstorms from KCLE to KMFD west. There
will likely be a brief break in precipitation before the next
round of showers begin to lift into the area towards after 06Z
tonight. This round of showers will likely bring better chances
of non-VFR conditions. There will likely be at least some
embedded thunder, but guidance is variable with the coverage.

Outlook...Non-VFR possible in showers and thunderstorms
Monday. Periodic Non-VFR conditions may persist in scattered
showers and thunderstorms on Tuesday and Wednesday.
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&&

.MARINE...
Low pressure over the Plains will move northeast towards the region
today, extending a warm front north of Lake Erie this afternoon.
This will result in east winds of 5-10 knots transitioning to south-
southwest winds at 10-15 knots which will persist into Monday. On
Monday, a cold front will move east, again shifting the winds to
gain a more westerly component and increasing to 15-20 knots for the
nearshore waters and up to 25 knots for the open waters. With an
established onshore component, waves will build to 3-5 feet
throughout the day on Monday, additionally creating hazardous
swimming conditions with an increased risk of rip currents. One or
two additional weak cold front will move east across the area on
Tuesday and Wednesday, keeping winds from west-northwest, but
gradually weakening them to 10-15 knots by Wednesday morning. This
period will likely need a Small Craft Advisory, but held off for one
more forecast period to get a better handle on timing.

Late Wednesday into Thursday, high pressure will build across the
region, allowing for winds on Lake Erie to persist on Thursday from
the north-northwest at 10-15 knots before weakening to below 10
knots through the end of the week.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
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OH...Dense Fog Advisory until 10 AM EDT this morning for OHZ011-013-
     014-021>023-033.
PA...Dense Fog Advisory until 10 AM EDT this morning for PAZ002-003.
NY...None.
MARINE...None.
-- End Changed Discussion --

&&

$$

SYNOPSIS...Maines
NEAR TERM...Maines
SHORT TERM...Campbell
LONG TERM...Campbell
AVIATION...Maines
MARINE...Campbell