-- Discussion containing changed information from previous version are highlighted. --
436
FXUS61 KCLE 140537
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
137 AM EDT Tue May 14 2024

.SYNOPSIS...
A cold front will slowly sag across the region tonight through
early Wednesday as low pressure slowly tracks from the
Mississippi Valley tonight to the Ohio Valley by Wednesday. High
pressure will finally build in by Thursday before low pressure
moves into the northern Great Lakes Friday and drags another
cold front into the region.

&&

.NEAR TERM /THROUGH TODAY/...
Will continue a dry forecast for the first half of the
overnight. The main concern for rain will be the batch along the
Ohio River in southern Indiana and northern Kentucky that will
lift north and enter the region late tonight. Low confidence in
the coverage and will keep the iso/sct wording in the forecast.

Most of Previous Discussion...
By tonight, the broad shortwave will start to cross the Mid
Mississippi Valley with an associated surface low moving through
southern Missouri into southern Illinois. This will be a slow
process however since this shortwave will continue to be fairly
closed off and separated from the polar and subtropical branches
of the jet, causing the nearly vertically stacked low to not
make much eastward progress through the period. The center of
the system only looks to reach the vicinity of southern Indiana,
southern Ohio, and northern Kentucky by early Wednesday. As
this shortwave/vertically stacked low migrates slowly eastward
tonight through Tuesday night, a cold frontal boundary will
slowly sag through the region from NW to SE. This all points to
increasing chances for showers and a few pockets of convection
tonight and Tuesday, with the rain chances only slowly tapering
off from NW to SE Tuesday night into Wednesday. Despite the
elevated rain chances through the period, coverage does not
appear to be overly widespread (more scattered in nature). This
is due to weak overall forcing with this system being displaced
from the jet dynamics. However, persistent moisture advection
and weak isentropic ascent as the center of circulation slowly
progresses east combined with some mid-level PVA supports high
chance to likely PoPs, with the greatest coverage coinciding
with the diurnal maximum Tuesday afternoon. Most of the rain
will be light, but locally higher amounts will occur with any
convection. The best opportunity for convection/thunder will be
Tuesday afternoon when HREF guidance projects a few hundred
joules of surface based CAPE.

Lows tonight will range from the upper 50s to low 60s. Highs
Tuesday will stay in the low/mid 70s due to the increased clouds
and precip. Lows Tuesday night will average mid/upper 50s as
cooler air gradually filters in.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
Surface low pressure will be tracking through the Ohio Valley
Wednesday morning as an upper trough and embedded closed upper low
trail just behind it. Guidance has been trending gradually slower
over the last few runs with the departure of this system and the
area will still be along or just ahead of the upper trough axis
Wednesday morning. It`s looking increasingly likely that showers and
perhaps some thunder will be around on Wednesday, taking longest to
exit our eastern/southeastern counties. This has led to POPs for
Wednesday trending a bit higher with further room to trend up if the
recent trends prove to be correct. We should dry out later Wednesday
afternoon through Wednesday night. Thursday looks to be mainly dry
as an upper-level ridge axis slides through, though a combination of
some weak instability developing with heating and the next shortwave
approaching from the southwest late in the day may lead to at least
isolated to widely scattered shower/thunder chances late in the
day...especially across far eastern OH and PA, and from the west
into the I-75 corridor. POPs spread east Thursday night as the
shortwave slides through, though we`ll be fighting nocturnal
stabilization and the forcing should be modest well ahead of the
next front, so generally have chance POPs for Thursday night.

Highs on Wednesday are expected to range from the mid 60s to lower
70s, warming into the low to mid 70s for Thursday. Nighttime lows
settle well into the low to mid 50s Wednesday night, trending a bit
milder (from the mid 50s to near 60 for most) Thursday night. Not
expecting any severe weather this period. Slow cell motions could
lead to locally heavy rain on Wednesday, though any flooding
potential should be quite isolated and may depend on if any heavier
rain amounts occur in the near term and saturate the ground more.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
A warm and somewhat unsettled long term forecast period is on tap.
For Friday, a trough and associated cold front will be approaching
from the west with ridging along the East Coast. Expect sufficient
moisture return and instability ahead of the front for decent shower
and storm chances Friday afternoon and evening. Agreement on timing
of the trough and frontal passage for Friday has improved enough to
introduce likely (60-70%) POPs. We should dry out Friday night into
Saturday as the trough and cold front exit east, though there is
still enough uncertainty regarding how quickly the system exits to
linger low POPs through Saturday, especially farther east/southeast.
Saturday night and Sunday should be mainly dry as ridging builds in
from the southwest. We may need to monitor for a decaying cluster of
showers/storms to ride overtop the ridge and bring some clouds and
rain potential, especially on Sunday as a warm front lifts through.
Confidence in the timing / placement of such a feature this far out
is quite low. Overall it should be a mainly dry weekend, though with
some uncertainty revolving around if it does rain a bit at some
point. Greater shower and storm potential is possible Sunday night
or Monday as the next shortwave and cold front approach from the
west/northwest, though confidence in details that far out is low.

Temperatures will be slightly above normal (generally in the 70s)
Friday and Saturday. While the exact values may depend on the timing
and coverage of any rain, much of the area has the potential to
surge into the 80s both Sunday and Monday.

&&

.AVIATION /06Z Tuesday THROUGH Saturday/...
-- Changed Discussion --
Widespread VFR conditions are expected to continue through much
of this period with the exception of periodic diminished
conditions to MVFR in showers that develop. Currently a cold
front is located west of the area and will very slowly move east
before becoming near stationary this afternoon. This front slows
so much primarily due to an interaction with it and an upper
level trough/surface low over the western Ohio River Valley.
Much of the forcing needed for shower development will occur
when this low move east across the Ohio River Valley late today
into Wednesday, increasing the confidence in showers and
thunderstorms after this TAF period. There is consistency in
models that suggest some light showers will build north over the
area this afternoon into the evening, but they should remain
scattered in nature making it very difficult to pinpoint timing
for showers in the TAF. Opted to introduce VCSH/VCTS this
afternoon with -SHRA expected for most terminals after 00Z
Wednesday. If the boundary slows anymore, the chances of shower
development will be pushed even later and likely into the next
TAF period so will continue to monitor. With this update, only
opted to decreased KMFD to MVFR ceilings with lowering of cloud
decks expected as the low pushes closer to the area, but
confidence wasn`t high enough elsewhere. Cannot rule out brief
MVFR visibilities in the heaviest showers today as well.

Southwest winds of 5-10 knots will persist through this
afternoon before gradually shifting to become east-northeast
tonight. Overnight winds will be light and variable expect in
heavier showers/thunderstorms.

Outlook...Non-VFR possible in showers and thunderstorms Tuesday
night through Wednesday and again on Friday through Saturday.
-- End Changed Discussion --

&&

.MARINE...
Generally light (15 knot or less) southerly flow continues through
Tuesday morning ahead of a cold front. The cold front will sink
south across the lake Tuesday afternoon, flipping winds around to
the north-northeast. These north-northeast winds do pick up to
around 15 knots Tuesday night into Wednesday as weak low pressure
tracks across the Ohio Valley. This will build some 2 to 4 footers
west of Cleveland Tuesday night into Wednesday morning. The wind and
wave forecast remains below small craft criteria for this period,
though it does get fairly close for a time late Tuesday night or
Wednesday morning. Will continue to monitor trends in the forecast
given the notoriously annoying northeast wind direction. Winds
become generally east-northeast through Thursday and should subside
enough by Wednesday afternoon to allow waves to diminish more into a
1 to 3 foot range, if not simply 2 or less Wednesday night and
Thursday. Winds flip around to the south-southwest Thursday night
into Friday ahead of a cold front. Winds will vary some through the
weekend as fronts glance the lake but generally look to remain out
of a west to south direction with headlines appearing unlikely.

A few thunderstorms are possible over the lake Tuesday into Tuesday
evening with a cold front, and may again be possible late Thursday
night and Friday ahead of a cold front. Additional thunderstorm
chances are possible Sunday and Monday but with low confidence.

&&

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

&&

$$

SYNOPSIS...Garuckas
NEAR TERM...Garuckas/Sefcovic
SHORT TERM...Sullivan
LONG TERM...Sullivan
AVIATION...Campbell
MARINE...Sullivan