847
FXUS61 KCLE 021836
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
236 PM EDT Sun Jun 2 2024

.SYNOPSIS...
Weak low pressure moves through the southern Great Lakes today.
High pressure briefly returns tonight and Monday before a warm
front lifts north Monday night. Low pressure will cross the
Upper Great Lakes on Wednesday and push a cold front through the
local area Wednesday night or Thursday morning.

&&

.NEAR TERM /THROUGH MONDAY/...
Breaks in the clouds across NW Ohio have allowed a minimal
amount of instability to develop. Regional radars show scattered
showers starting to develop both ahead of and along the front
while morning activity is still exiting to the east. Left a
slight chance of thunderstorms in the forecast mainly west of a
line from Cleveland to Akron but chances of thunder are pretty
low given warming in the mid-levels and meager instability. With
that said, did raise pops slightly and linger them into the
evening an extra hour or two as several 12Z CAMs show showers
filling in along the front. Eastern areas still remain rather
cool with temperatures in the low to mid 60s at 2 PM.

Previous discussion...A shortwave trough axis and associated
trough of surface low pressure are moving across the local area
this morning. The shortwave will exit to the east by the mid-
late afternoon hours. Modest ascent head of the shortwave trough
axis (largely in the form of isentropic lift/warm air
advection) is supporting fairly numerous light to briefly
moderate showers. While the system is on a slow weakening trend
showers will be fairly numerous ahead of the shortwave. A drying
trend is expected from west to east as the shortwave shifts
east. While this will lead to an increasingly drier forecast
later this morning into this afternoon from west to east,
convergence associated with the surface trough of low pressure
will combine with modest destabilization of a moist low-level
airmass to support isolated to scattered shower re-development
across Northwest and North Central Ohio this afternoon, with
this pop-up activity spreading into Northeast OH late this
afternoon into this evening. This is enough to keep low POPs
going into early this evening. Maintained a slight thunder
mention generally west of I-77 this afternoon, though thunder
potential will be limited by warming mid-levels and there`s no
severe wx concern. Much of the area will see 0.10" or less of
additional rainfall today...though a few more moderate showers
could produce highly localized amounts up to 0.50". There will
be some limited breaks of sun by this afternoon, especially out
west, with highs ranging from the upper 60s across PA and far
eastern Ohio to the upper 70s along the I-75 corridor.

Lingering pop-up showers should fade fairly quickly with the
setting of the sun this evening. Weak ridging surface and aloft
will lead to a quiet forecast tonight and into Monday. With
plentiful low-level moisture and light winds tonight fog
development is a concern. There is some question over how
quickly a broken low cloud deck erodes this evening, though
where skies clear expect at least patchy fog to develop
overnight. More widespread and dense fog is possible...given a
radiation fog setup river valleys will be the greatest concern.
Otherwise, hi-res guidance generally likes the Mid Ohio region
for potentially more widespread / dense fog, with some potential
to leak into Northwest Ohio and interior portions of Northeast
Ohio and Northwest PA if clearing is more widespread. A weak
shortwave moves through Monday afternoon and some hi-res models
toy with popping a few showers along any lingering low-level
convergence zones during the afternoon. Forecast soundings
reveal warm and dry mid- levels on Monday and a majority of
models remain dry. Given the lack of stronger forcing and
arguments against rain held a dry forecast for the day. Lows
tonight will generally settle into the upper 50s and lower 60s.
Highs on Monday will range from the upper 70s to mid 80s.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
High pressure departs to the east coast Monday night with a weak
warm front lifting northeastward across the area on the backside of
the departing high. Southerly flow ensues, with temperatures rising
to the mid to upper 80s by Tuesday afternoon. Moisture content will
be on the rise as well with dew points into the low to mid 60s on
Tuesday. Some modest uncapped instability should develop Tuesday
afternoon in response to increasing surface T/Td, and some models
have convection developing to our west (i.e. Indiana) in advance of
a shortwave trough lifting northeast across the state. This is a low
predictability situation though because there is large spread in
model guidance prediction of the shortwave trough evolution, which
makes it uncertain when and where convection develops during the
afternoon. Additionally, shear is weak, and MLCIN develops during
the evening/overnight so even if convection develops out west,
there`s no guarantee it continues eastward into our forecast area.
For now, have gradually increasing low PoPs from west to east
(generally in the 20-40% range) to account for this potential.

Meanwhile an upper-level negatively-tilted trough builds in from the
west, with the trough axis extending southeastward to just west of
the Great Lakes region Wednesday morning. Southerly flow continues
to build the moisture within the warm sector, with dew points likely
into the mid to upper 60s. As this trough approaches, this should
contribute to moderate instability and convection developing within
the warm sector during the afternoon/evening hours across the
forecast area. Confidence is high in the occurrence of showers and
thunderstorms areawide, so continued to gradually increased PoPs to
80-90%, primarily targeted towards a couple hours of showers and
storms during the afternoon/evening hours. Most model guidance have
25-40 knots of mid-level southwesterly flow, which should contribute
to a low-end severe weather threat.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
The upper-level low builds into the Great Lakes region on Thursday,
remaining there through Saturday. The actual evolution of the upper-
level has some spread but the overall trend and pattern of the
forecast is fairly consistent with cooler than normal temperatures
(talking highs around 70) and showery pattern. It`s difficult to
pinpoint when exactly are the best chances for showers but that will
become more apparent as we get closer. GFS/CMC are cooler and more
showers, while the ECMWF has the low centered a bit farther north
with less precipitation.

&&

.AVIATION /18Z Sunday THROUGH Friday/...
Light showers are exiting the area to the east while scattered
showers are filling back in along the cold front in NW Ohio from
roughly PCW to FDY. Given the lingering low level moisture and
weak instability expect showers to continue to fill in and move
southeast through early evening. Added a tempo for showers to
the forecast at FDY and MFD and may need to add to CAK if they
hold together and approach the terminal after 22Z. Any shower
could produce brief MVFR visibilities. Chances of thunder are
too low to include in the terminals but can not entirely rule an
isolated storm given the weak instability.

For tonight, low level moisture is expected to remain high with
very light winds. Breaks in the clouds are likely to widespread
IFR conditions with low stratus and fog. Fog could be dense,
especially in the window from 09-13Z. Terminals most likely to
experience dense fog are TOL/MFD/CAK/YNG. Light downsloping
winds may keep visibilities up closer to a half mile or a mile
at CLE/ERI. Ceilings should lift and visibilities improve
quickly on Monday morning between 13-15Z. Clouds will gradually
scatter out into afternoon.

South to southwest winds of 10 knots or less today will shift to
the west or northwest behind the front at TOL/FDY. The front
tends to weaken before making it farther east and winds are more
likely to go light and variable or calm after 01Z. Winds will
return out of the south on Monday morning.

Outlook...Thunderstorms and associated non-VFR possible at
times Tuesday through Friday.

&&

.MARINE...
A weak low moving east across Lake Erie has resulted in brief 15-20
knot winds in the western basin early this morning, though this
should rapidly taper off though as this low dissipates and fills in,
being replaces by a high pressure ridge by tonight. Afternoon lake
breeze develops on Monday, with some locally enhanced onshore flow
likely in the immediate nearshore, especially in the western basin
with east to northeast flow. Southerly flow prevails on Tuesday and
Wednesday, with speeds possibly approaching 15-20 knots during the
day Wednesday before a cold front crosses the lake Wednesday
evening/night. West to southwest flow likely to develop behind the
front with periods of 15-20 knots possible. Some small craft
advisory and beach hazard statements may be needed at some points
Wednesday night onward.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...Sullivan
NEAR TERM...KEC/Sullivan
SHORT TERM...Saunders
LONG TERM...Saunders
AVIATION...KEC
MARINE...Saunders