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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCLE 141355
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
955 AM EDT Sun Apr 14 2024

.SYNOPSIS...
A ridge exits eastward before a cold front sweeps southward
through northern Ohio and northwest Pennsylvania this evening.
Behind the front, another ridge builds from the north-central
United States and vicinity through Monday. The ridge then exits
generally eastward on Monday night through Tuesday as a warm front
approaches from the Mid Ohio Valley and vicinity.

&&

.NEAR TERM /THROUGH MONDAY/...
-- Changed Discussion --
A look at area soundings indicates that the low levels of the
atmosphere are rather dry. There should be deep mixing today so
any cumulus that develop should be a bit higher based than
usual for this time of year. The deeper mixing will allow for
gusty winds through mid afternoon then decreasing into the
evening as the cold front approaches. The deeper mix will also
allow temperatures to be slightly warmer than earlier thinking.
We have nudged highs up slightly, especially across NW OH. A
few spots may touch 80 degrees.

The better depth of moisture looks to be in the 925mb to 700 mb
levels near and east of I-77. This would be the region where the
greatest chances of thunder exist. However locations further to
the west still will see some isolated/scattered thunderstorms.
The potential for damaging winds and larger hail remains near
and south of a line from Wattsburg to Upper Sandusky. We will
continue to monitor for any low level convergence which will
drive the initial convection.

Previous Discussion...
Cyclonic NW`erly flow aloft and embedded shortwave disturbances
affect northern OH and NW PA through tonight. At the surface, a
ridge exits generally E`ward before a cold front sweeps S`ward
through our region this evening. Behind the front, another ridge
builds from the north-central United States and vicinity.
Intervals of sunshine, daytime heating, and low-level WAA are
expected to allow highs to reach mainly the lower to mid 70`s in
NW PA and mainly the 70`s to 80F in northern OH late this
afternoon. In addition, diurnal convective mixing of the
boundary layer tapping into stronger flow aloft will allow
SW`erly surface gusts to reach as high as 30 to 40 mph late this
morning through early evening, ahead of the front. Low-level
CAA behind the front and nocturnal cooling should allow
overnight lows to reach the 40`s to lower 50`s around daybreak
Monday.

Primarily fair weather is expected through this early afternoon
as an elevated mixed layer (EML) and attendant strong capping
inversion aloft continue to overspread our region from the Upper
Midwest. However, moist isentropic ascent aloft and the release
of weak, solely elevated CAPE ahead of a shortwave trough axis
and along the nose of a WSW`erly LLJ should trigger a few
showers and thunderstorms amidst moderate effective bulk shear
over/near eastern Lake Erie and NW PA this morning, especially
between roughly 6 AM and 10 AM EDT. Given steep mid-level lapse
rates accompanying the EML, small hail may accompany any morning
thunderstorms. This convection should end by midday due, in
part, to weakening of the nocturnal LLJ.

Mid-level cooling and large-scale ascent tied to the aforementioned
shortwave troughs are expected to weaken the EML`s capping
inversion over the course of today. As a result, isolated to
scattered, surface-based, and organized thunderstorms are
expected to develop along the S`ward-moving cold front and pre-
front surface trough axis from about mid-afternoon through
evening as the front encounters moderate to strong effective
bulk shear, non-excessive boundary layer CIN, and weak to
moderate boundary layer CAPE. The combination of daytime heating
and surface dew points of about 50F to 55F will allow the
greatest boundary layer CAPE to materialize this afternoon
through early evening before the warm sector boundary layer
stabilizes via nocturnal cooling later this evening. Severe
thunderstorms in the form of multicells and supercells are
possible this afternoon into early evening. Damaging convective
wind gusts amidst DCAPE near 500 to 1000 J/kg and damaging hail
the size of quarters to perhaps hen eggs (i.e. 1" to perhaps 2"
in diameter) courtesy of steep mid-level lapse rates, hail
growth zone MUCAPE of 400 to 600 J/kg, and favorable melting
levels near 10kft AGL are expected to be the main severe
convective weather hazards. The greatest potential for severe
hail will accompany the relatively-strong updraft of any
supercell. Low-level winds veering slightly and increasing
quickly with height will yield strong surface-based ESRH, which
may support the development of a tornadic supercell. However,
mixed layer LCL`s near 1500 to 1750 meters AGL should curb
tornado potential. Unusually-high PWAT`s are expected within the
warm sector and will allow showers and storms to produce
torrential rainfall. Given soils are already very wet, localized
flash flooding may develop where multiple rounds of showers and
storms manage to occur. Compared to 24-hours ago, the concern
for localized flash flooding has increased given W`erly mean
mid-level flow is now expected to essentially parallel the cold
front and pre-front surface trough axis, which should lead to
training convection, especially if convection coverage is
scattered along/ahead of the front. The best potential for
showers/storms, including severe storms, exists east of roughly
I-71 and south of roughly I-90. Fair weather is expected CWA-
wide after midnight tonight, following the passage of the cold
front.

Fair weather is expected on Monday as the aforementioned high
pressure ridge at the surface and aloft builds from the north-
central United States and western Great Lakes, and is accompanied
by stabilizing subsidence. A weak synoptic MSLP gradient and
sufficient daytime heating of surrounding land will allow a lake
breeze to occur and impact locations within several miles of
Lake Erie during the late morning through early evening. Late
afternoon highs are expected to range from the mid 50`s to lower
60`s in NW PA and the mid 50`s to lower 70`s in northern OH.
The coolest highs are expected within several miles of Lake
Erie, while the warmest highs are expected well to the west and
south in the OH portion of our CWA.
-- End Changed Discussion --

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Surface high pressure and upper ridging will gradually build
eastward Monday night into Tuesday morning as low pressure centered
over the Great Plains lifts a warm front northeastward across the
northern Ohio Valley. Precipitation likely arrives Tuesday afternoon
moving from southwest to northeast through the evening hours.
Showers with some embedded thunderstorms are possible Tuesday
afternoon, though there continues to be some model differences in
how much instability will be realized. Rainy weather continues
through Wednesday as the parent low enters the Upper Midwest and
drags a cold front east across Northern Ohio. Can`t rule out some
embedded thunderstorms ahead of the cold front Wednesday afternoon
but the question remains on how unstable we`ll be able to get given
lingering showers and cloud debris from precipitation associated
with the warm front on Tuesday.

The warm front will allow for above normal temperatures in the short
term period with highs in the upper 60s to lower 70s Tuesday rising
into the low to mid 70s on Wednesday. Lows in the 40s Monday night,
mid to upper 50s Tuesday night, and low 50s Wednesday night.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
Unsettled weather will continue into the beginning of the long term
period as the aforementioned low drags a secondary cold front
eastward across the local area on Thursday. We may see a brief dry
period as an upper ridge and surface high attempt to build overhead
on Friday before another upper level trough digs south Friday
evening. Have slight chance to chance PoPs in place through
Saturday.

Near normal temperatures in the 60s on Thursday before cooler
weather returns to the region as high temperatures fall into the
lower 50s by Saturday.

&&

.AVIATION /12Z Sunday THROUGH Thursday/...
Cyclonic NW`erly flow aloft and embedded disturbances affect
our region through 12Z/Mon. At the surface, a ridge exits
generally E`ward before a cold front sweeps generally S`ward
through our area between ~22Z/Sun and ~04Z/Mon. Behind the
front, a ridge builds from the north-central United States and
vicinity. Our regional surface winds trend S`erly to W`erly
around 10 to 20 knots ahead of the front. Gusts up to 20 to 35
knots are expected, especially between ~14Z and ~23Z/Sun. Note:
LLWS is expected over northern OH prior to 14Z/Sun as a WSW`erly
jet streak of about 50 knots at/near 925 mb affects the area.
Behind the front, NW`erly surface winds around 10 to 15 knots
are expected for several hours before becoming variable in
direction and easing to around 5 knots as a relaxing MSLP
gradient accompanies the post-front ridge.

Primarily fair weather and VFR are expected during the TAF
period. However, ascent ahead of a subtle disturbance aloft may
trigger isolated showers/thunderstorms over/near eastern Lake
Erie and NW PA through ~14Z/Sun. Additional isolated to scattered
showers and thunderstorms are expected along and just ahead of
the cold front, especially south of roughly I-90 and east of
roughly I-71. These storms may produce brief/erratic surface
gusts up to 55 knots and damaging hail. The cold front-related
showers/storms should last no more than several hours at any
impacted TAF site. Brief MVFR/IFR are possible with
showers/storms.

Outlook...Non-VFR expected with periodic rain showers and
thunderstorms Tuesday through Thursday.

&&

.MARINE...
Ended up expanding the small craft advisory to cover all nearshore
zones of Lake Erie has a strong 40-50 knot low level jet moves
overhead through this evening. This should allow for higher westerly
winds in excess of 20 knots to mix down to the surface through this
evening. High pressure briefly builds in behind a cold front late
tonight into Monday. The high will allow for winds to diminish below
10 knots. Easterly winds increase to 15-20 knots on Tuesday
afternoon ahead of another warm front. Winds will turn southerly by
Wednesday afternoon as a cold front swings eastward across the lake.
Westerly winds will finally fall below 20 knots Thursday into Friday
as high pressure builds in behind a secondary cold front late
Thursday night.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...Small Craft Advisory until 6 PM EDT this evening for
     LEZ142>145.
     Small Craft Advisory until 8 PM EDT this evening for
     LEZ146>149.

&&

$$

SYNOPSIS...Jaszka/MM
NEAR TERM...Jaszka/MM
SHORT TERM...Iverson
LONG TERM...Iverson
AVIATION...Jaszka
MARINE...Iverson