-- Discussion containing changed information from previous version are highlighted. --
954
FXUS61 KCLE 281058
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
658 AM EDT Tue May 28 2024

.SYNOPSIS...
A cold front will cross the region this morning with a broad
trough of low pressure remaining over the Great Lakes and Ohio
Valley in its wake through Wednesday. High pressure will start
to build in from the northwest late Wednesday then will become
centered overhead Thursday and Friday.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
6:30 AM Update...

Increased PoPs along the lakeshore of north central and NE Ohio
this morning since showers are moving onshore a little faster
than expected as a shortwave and associated cold front moves in.
Otherwise, today`s forecast remains on track.

Original Discussion...

An unseasonably cool pattern will be found across the Great
Lakes, Ohio Valley, and Northeast U.S. through Wednesday as an
amplified pattern characterized by a strong mid/upper ridge
over the Rockies and Plains and downstream mid/upper trough over
the eastern U.S. keeps conditions cool and unsettled. Multiple
shortwaves pivoting through the NW flow and their associated
moisture and lift will generate waves of showers, and diurnal
heating each afternoon will lead to pockets of thunder, but
timing of the greatest precip chances is relatively low
confidence. It will definitely not rain all of the time, and dry
time will be much longer than the duration of precip, but all
areas will see at least some rain during the period.

In terms of details, IR satellite and water vapor loops early
this morning show the mid/upper trough axis digging across the
Upper Midwest and Great Lakes. One lead shortwave currently
positioned from roughly Detroit to Indianapolis will cross the
region after sunrise leading to an expansion of showers as mid-
level moisture increases. Regional radar already shows showers
increasing in SE Lower Michigan and southern Ontario tied to
this mid-level moisture and lift, and expect these to spill
across the lake as the shortwave pivots through, so have
increasing PoPs this morning. As the shortwave progresses E/SE
this afternoon, even cooler air aloft (500 mb temps around -3 C)
combined with wraparound moisture and even subtle lake
enhancement as the boundary layer flow veers W to NW will
support fairly widespread showers in NE Ohio and NW PA. Daytime
heating from the very strong late May sun beneath this cold air
aloft will steepen low and mid-level lapse rates to near 7 C/Km
leading to SBCAPE over 1000 J/Kg, so expect scattered
thunderstorms to develop in all areas away from the lake,
although the greatest precip coverage will be in the
aforementioned areas of NE Ohio and NW PA. Again, it will not
rain all of the time, but expect good coverage this afternoon,
especially in the NE areas. Small hail could accompany the
strongest convective cells given the cold air aloft, along with
gusty winds of 30-40 knots.

Expect showers to decrease in coverage this evening before the
next shortwave rotates across the region late this evening into
tonight. This shortwave looks to be stronger with a mid-level
low and associated PVA dropping through Lower Michigan and
across Lake Erie by Wednesday morning, so expect all areas to
see some rain tonight into Wednesday morning. In fact, this may
be the best window to see some steadier rain, so areas that miss
out this afternoon will likely see some rain tonight into
Wednesday morning. Amounts look to be light though with QPF only
averaging a few tenths to 0.30 inches. Drier air will gradually
work in from the north Wednesday afternoon as the
shortwave/mid-level low departs to the SE and large surface high
pressure over the Upper Midwest tries to extend ridging into
the region, but deep longwave mid/upper troughing remaining
overhead will keep temperatures well below normal.

Highs today will show quite a bit of spread with mid/upper 60s
in NE Ohio and NW PA where precip coverage is greatest and low
70s in north central and NW Ohio. Wednesday will be cooler with
highs in the mid/upper 60s areawide. Lows tonight will average
low/mid 50s.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
Upper trough will remain over the eastern Great Lakes through
Thursday, but dry weather will return by the start of the period as
a strong surface high building east over the Great Lakes pushes dry
air over the area. Northwest flow will result in continued below
normal temperatures Wednesday night through Thursday night with
overnight lows in the low to mid 40s (50s closer to the lakeshore)
and Thursday`s highs reaching the mid to upper 60s to around 70
degrees. There will be a decent amount of radiational cooling with
light winds and clear skies Wednesday and Thursday nights, so may
need to keep an eye on the potential for slightly cooler temps in
the upper 30s, primarily in higher elevations of interior NE OH and
NW PA.

The trough will fully exit to the east Thursday night as a ridge
builds east from the Mississippi Valley and the surface high centers
over the local area. Dry weather will prevail through Friday night
and temperatures will begin to moderate to near normal values with
highs in the 70s expected areawide. While there will be radiational
cooling Friday night, the ridge axis will likely center over the
area Friday night so overnight lows will likely be a few degrees
warmer.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
Surface high and upper ridge axis will drift east of the area
Saturday with zonal flow developing over the area by Saturday
afternoon. A shortwave may ripple across the region Saturday
afternoon/evening, which could result in a small chance of
showers/thunderstorms. Guidance diverges from there, but another
shortwave or trough may lift northeast into the Ohio and Tennessee
valleys late Sunday into Monday. Either way, the zonal flow will
provide chances for diurnal showers/thunderstorms, so have slight
chance to chance PoPs Saturday afternoon through Monday.

Temperatures continue to rise this weekend into early next week.
Expect highs in the mid to upper 70s Saturday with afternoon temps
climbing back into the 80s for Sunday and Monday.

&&

.AVIATION /12Z Tuesday THROUGH Saturday/...
-- Changed Discussion --
Low confidence TAF forecast as a shortwave and associated cold
front this morning generates scattered showers followed by more
diurnally driven showers and thunderstorms this afternoon. The
scattered nature makes it difficult to time when precip may
impact a terminal, but VFR should generally prevail outside of
precip. The exception is a period of longer MVFR to IFR this
morning in NE Ohio and NW PA which should improve this
afternoon. Otherwise, drops in cigs and vis should be mainly
tied to showers and thunder. By tonight, a stronger shortwave
will generate a more widespread area of rain, and that could
support longer periods of MVFR or lower cigs and vis.

WSW winds of 10-20 knots early this morning will turn more
W to NW from mid morning through the afternoon with speeds
staying in the 10-20 knot range. Occasionally higher gusts will
occur this afternoon.

Outlook...Periodic Non-VFR conditions may exist in scattered
showers and thunderstorms through Wednesday.
-- End Changed Discussion --

&&

.MARINE...
Northwest winds 15 to 20 knots will continue on Lake Erie with waves
of 3 to 6 feet expected east of The Islands through this afternoon.
Winds will gradually diminish this afternoon and all marine
headlines should end by no later than 00Z/8 PM this evening when
winds diminish to 10 to 15 knots. North/northwest flow continues
through Wednesday and additional Small Craft Advisories/Beach
Hazards Statements will likely be needed as winds increase to 15 to
20 knots behind a reinforcing cold front Wednesday afternoon into
Wednesday night. Winds should diminish to 15 knots or less by
Thursday morning with similar flow persisting through Thursday night
before winds become a bit more light and variable Friday. A ridge
axis will cross the lake Friday night, allowing winds to shift to
the southeast through Saturday. Do not anticipate any marine
headlines Thursday through Saturday.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Beach Hazards Statement until 5 PM EDT this afternoon for
     OHZ009-010.
     Beach Hazards Statement through this evening for OHZ011-012-
     089.
PA...Beach Hazards Statement through this evening for PAZ001.
NY...None.
MARINE...Small Craft Advisory until 5 PM EDT this afternoon for LEZ144-
     145.
     Small Craft Advisory until 8 PM EDT this evening for
     LEZ146>149.

&&

$$

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