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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCLE 250129
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
929 PM EDT Sat Oct 24 2020

.SYNOPSIS...
High pressure will build east across the Great Lakes tonight
into New England on Sunday. A trough will move northeast through
the Ohio valley late Sunday into Monday. A stationary boundary
will set up just south of the area early next week before high
pressure builds across the region by midweek.

&&

.NEAR TERM /THROUGH SUNDAY NIGHT/...
Cloudy skies continue to linger across much of the area,
although NW Ohio has cleared out for the time being, allowing
temperatures to quickly drop over the area into the upper 30s.
Light winds around 5 knots are beginning to shift and become
northeasterly as the ridge continues to push eastward over the
area. Weak instability across the lake, coupled with the wind
direction, should give way to light lake effect rain showers
along the western lakeshore of Lake Erie through the overnight
hours. Opted to continue the chance PoPs with reports of patches
of steady rain with onshore bands earlier. However, agree with
earlier discussion that this may be overdoing it. A band of
clouds will develop with these showers, again making NW Ohio
cloudy. Overnight lows will drop into the low 30s in the
northeast to the upper 30s to low 40s out west. The remainder of
the discussion for Sunday remains on track and unchanged.

Any lake induced light precip/clouds will weaken/scatter through
the day on Sunday as the ridge moves into New England. Precip
chances will increase late in the day into Sunday night as an
inverted trough builds northeast through the upper Ohio valley
into the far eastern part of the area. This, in combination with
a tightening baroclinic zone and a vorticity stream moving
northeast along this boundary, will see an increase in cloud
cover and light precip chances through the night, with the
highest pops across the eastern part of the area. Highs on
Sunday will be a bit warmer, with low 50s expected. Lows Sunday
night will be in the upper 30s across NW PA to the low/mid 40s
elsewhere.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
An inverted trough over the region on Monday will allow for showers
to be possible over the eastern half of the forecast area to start
on Monday as a small vorticity maximum ripple through aloft. Rain
chances will decrease through the day as this feature exits the
region. The surface boundary will stall over the area for much of
the short term forecast period and be the focus for additional rain
development for Monday night into Tuesday as moisture advects back
into the region and another ripple of energy aloft will support rain
development. Will maintain higher PoPs across the area for the
Monday night period. Rain will taper off on Tuesday as the boundary
drifts south and moisture cuts off into the region but will maintain
chance PoPs while the boundary is still in the vicinity.
Temperatures through the period appear to remain on the cooler side
of normal; however, the range of temperatures between the GFS and
ECMWF solutions is large and will maintain temperatures near 50s for
highs.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The forecast area will find itself between systems on Wednesday with
mostly dry air and weak high pressure building into the area. Will
maintain a dry forecast with cooler than normal temperatures at this
time. An upper trough over the southern plains will advance east on
Thursday and support low pressure through the southern CONUS.
Placement and timing of the low is still uncertain as this system
will likely absorb a tropical feature from the Gulf of Mexico. With
that, will maintain some form of PoPs on Thursday into Friday with
the forecast area remaining on the cool side of this system. A
strong ridge and surface high pressure will build in for the
weekend, but this will come with cooler than normal temperatures for
the Halloween holiday.

&&

.AVIATION /00Z Sunday THROUGH Thursday/...
Much of the low cloud decks have begun to erode as the ridge
continues to build over the area, giving way to primarily VFR
conditions across the area. KMFD and KYNG still have ceiling
bouncing between MVFR and VFR which is expected through 03Z.
Winds are expected to shift from north to northeasterly and
remain at 5 to knots through the period. Light lake effect
showers may impact KTOL and KCLE periodically throughout the
overnight hours, however confidence in timing and duration are
not high so opted to keep it out of the TAFs. All sites should
improve to VFR conditions for the duration of the forecast
period, however remain cloudy as the next low pressure system
approaches the area toward the end of the period.

Outlook...Non-VFR expected with periods of SHRA Sunday night
through Wednesday.

&&

.MARINE...
A ridge will continue to enter the Great Lakes region tonight and
allow for winds to become more northeasterly over the lake. As this
feature increases in strength over the lake, winds will increase on
Sunday with winds to 20 knots over the central portions of the lake.
An unfavorable northeast fetch could allow for some higher waves in
the central and western basin, but for now should remain below small
craft criteria. A trough will sneak in from the south Sunday night
and winds will become more easterly over the lake, offshore in some
areas, and waves will be less problematic for the nearshore waters.
A cold front will sweep across the lake on Monday and winds will
shifts around to the north across the basin. The front will stall
over the Ohio Valley and north flow should continue over the lake.
High pressure will attempt to build in midweek and westerly winds
will be favored, no higher than 15 knots at this time.

&&

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

&&

$$
SYNOPSIS...Greenawalt
NEAR TERM...Campbell/Greenawalt
SHORT TERM...Sefcovic
LONG TERM...Sefcovic
AVIATION...Campbell
MARINE...Griffin/Sefcovic