-- Discussion containing changed information from previous version are highlighted. --
537
FXUS61 KCLE 300607
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
207 AM EDT Tue Apr 30 2024

.SYNOPSIS...
A cold front will move east across the area tonight into
Tuesday. High pressure will return to the area late Tuesday
through Wednesday before another low pressure system moving
through the Midwest moves a warm front north across the area
Wednesday night into Thursday. A cold front associated with this
low will move east Friday night into Saturday.

&&

.NEAR TERM /THROUGH TONIGHT/...
905 PM Update...
Have an outlfow boundary that is cutting through the Cleveland
area with a 202-5kt gust but also providing an initiation point
for new cell development out ahead of the main line of showers
with embedded thunder. Lightning has been hard to come by this
evening, but the threat going into the overnight is still non-
zero. POPs adjusted for latest mesoscale developments with minor
edits to the overnight low temperatures.

Previous Discussion...
Currently a low pressure system over the Upper Midwest has
extended a warm front north of the area with a cold front
extending south near the IN/IL border. This has left the entire
CWA in the warm sector of this low today, allowing for continued
WAA and moisture advection. Looking at observations,
temperatures have climbed into the upper 70s to low 80s with
dewpoints in the mid to upper 50s. These conditions have allowed
for a field of diurnal CU to become established over much of
the area. These skies will gradually transition to overcast
skies as the aforementioned cold front continues to move east
towards the area this evening and overnight. In addition,
showers and thunderstorms are currently being observed upstream
and are expected to gradually push east beginning this evening.
Overall the mesoscale environment remains marginal, but with a
nose of instability and wind shear 30-35 knots over NW OH, would
not be surprised to see some stronger thunderstorms with the
primary concern being heavy rainfall and gusty winds between
21-00Z this evening. Due to the marginal environment, SPC has
maintained a general thunder outlook across the area.

As the cold front moves east tonight, showers will become more
widespread with the chance of thunder diminishing, especially
east of I71. Overall impacts should be minimal with this system,
although scattered heavier rainfall may result in nuisance
flooding such as ponding on roadways. QPF totals for the event
are highest in west counties generally ranging from 0.5-0.7" and
are much lower in the eastern counties once the system weakens
with total rainfall only expected to be 0.2" or less.

As the cold front departs east on Tuesday, high pressure will
build in behind it and allow for dry conditions to return for
the remainder of the near term period. High temperatures on
Tuesday will be a bit milder, climbing into the low to mid 70s.
Overnight lows will only drop into the low 60s with lows Tuesday
night cooler behind the cold front as they drop into the low
50s.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Broad mid/upper ridging will reamplify over the central and eastern
CONUS Wednesday in response to broader mid/upper troughing
developing over the northern Rockies. This will quickly bring back
temperatures that are 10-20 degrees above normal for Wednesday and
Thursday allowing trees, shrubs, and other vegetation to continue to
leaf out at a rapid pace this week. A lead shortwave ejecting out of
the main trough will progress through the Upper Midwest and northern
Great Lakes Wednesday, with an associated surface low traversing a
warm front lifting through the central lakes. At this time, think
any convection will stay north of the region given the building
ridge and warm frontal boundary lifting quickly north, so kept
Wednesday dry. A weak cold front may sag into the area behind this
deamplifying/weakening shortwave and surface low Wednesday night,
but it should wash out in response to heights continuing to build
through Thursday, so kept Wednesday night and Thursday dry as well.
By Thursday night, the main mid/upper trough over the Rockies will
progress toward the Upper Midwest while evolving into a vertically
stacked, closed low that will extend a cold front slowly eastward.
Have slight chances for showers/storms reaching NW Ohio Thursday
night, but most precip will hold off until Friday. More on that in
the Long Term section below.

Highs will reach the mid 70s to low 80s Wednesday, with upper 70s to
low 80s Thursday. Lows Wednesday night will range from the mid to
upper 50s, with upper 50s to low 60s Thursday night.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
The aforementioned closed low over the Upper Midwest will gradually
fill and lift north across the US/Canadian border Friday through
Saturday. The deterministic GFS, ECMWF, and Canadian are still
struggling to pinpoint how far east the closed low will make it
before it drifts into Canada, but the guidance is at least in
agreement on it lifting into Canada. This will extend an initial
cold front through the area Friday night. The mid/upper ridge over
the eastern CONUS will be very amplified/sharp ahead of this front
during the day Friday. Given this strong ridge and the closed low,
it is not surprising to see that the cold front has been slowing
down, with most guidance now showing a late Friday night into
Saturday morning frontal passage. Would not be surprised to see some
additional slowing. At this time, stayed with chance PoPs in the
warm sector for showers/storms ahead of the front Friday, but with
forcing trending farther west, most may hold off until Friday night.
Have likely PoPs Friday night into Saturday as the front slowly
moves eastward. The front will be weakening due to the upper support
becoming further displaced to the NW, so not expecting widespread
severe weather (overnight timing further reduces the potential), but
a few strong storms are possible given at least weak to moderate
instability and marginal shear. This looks like a better set-up for
slow moving convection with locally heavy rainfall due to the jet
dynamics displaced to the NW leading to weak flow. PWATs will be
seasonably high, so will need to watch for areas of slow moving or
training convection Friday night into Saturday.

Periods of showers and possibly thunderstorms will continue over
eastern areas through Saturday afternoon since the cold front will
be slow to exit, so kept likely PoPs in eastern Ohio and western PA.
We`ll again need to watch for locally heavy rainfall. There should
be some drying Saturday night into Sunday, but kept chance PoPs
through the entire Saturday night through Monday period because
guidance suggests a secondary cold front around Sunday or Sunday
night/Monday as a deeper trough attempts to dig into the Great Lakes
behind the departing closed low. Lots of uncertainty on timing with
this, but it will definitely not be a washout.

Highs in the 80s Friday will cool into the mid/upper 70s Saturday
through Monday.

&&

.AVIATION /06Z Tuesday THROUGH Saturday/...
-- Changed Discussion --
An area of rain with some localized embedded thunder continues
in a slow SSW to NNE orientation across the airspace this
morning. Rain will slowly propagate east across the terminals
with rain just exiting KTOL and about to enter KMFD and KCLE.
Rain will progress through the late morning hours. Some lower
ceilings will enter with the rain and some trend to MVFR is
expected but it may be in and out of the terminals, but not
worth getting cute over a prevailing vs. a TEMPO group. The MVFR
ceilings should persist briefly behind the rain before lifting
later in the afternoon. With the cold front out of the region,
dry air will enter and skies will clear this evening and into
tonight. Winds through the period will be generally light and
will shift from the south to the west with the frontal passage.

Outlook...Non-VFR may return in showers and thunderstorms
Thursday night through Saturday.
-- End Changed Discussion --

&&

.MARINE...
A quiet week is expected on the lake as pressure gradients remain
weak. WSW winds of 5-15 knots are expected behind a weakening cold
front tonight and Tuesday, becoming SW at 5-10 knots Tuesday night
and Wednesday. Winds then go light and variable Wednesday night
until turning east at 10-15 knots Thursday and SW at 10-15 knots by
Friday. SW winds will gradually weaken to 5-10 knots Friday night
and Saturday as a weakening cold front shifts eastward.

&&

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

&&

$$

SYNOPSIS...Campbell
NEAR TERM...Campbell/26
SHORT TERM...Garuckas
LONG TERM...Garuckas
AVIATION...Sefcovic
MARINE...Garuckas