CLE issues Area Forecast Discussion (AFD) at Apr 21, 4:24 AM EDT061
FXUS61 KCLE 210824
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
424 AM EDT Mon Apr 21 2025
.SYNOPSIS...
A low tracks northeastward from the Upper Mississippi Valley to
southwestern Quebec through daybreak Tuesday. Accordingly, the
attendant warm front sweeps northeastward through our region from
about daybreak through this late afternoon. The low's trailing
cold front should sweep eastward through our region from about
midday through this late evening. Behind the cold front, a ridge
builds from the Upper Midwest through Tuesday.
&&
.NEAR TERM /THROUGH TUESDAY/...
Aloft, a ridge exits toward the Canadian Maritimes through
nightfall Tuesday evening as a shortwave trough shifts NE'ward
from the Upper MS Valley to northern QC. Behind the shortwave
trough, another ridge builds from the north-central United
States through nightfall Tuesday evening. At the surface, the
shortwave trough's attendant low moves NE'ward from the Upper MS
Valley to northern QC and becomes vertically-stacked with the
mid/upper-level low embedded in the shortwave trough overnight
tonight through Tuesday. The low's surface warm front sweeps
NE'ward through our CWA from about daybreak through this late
afternoon, while the low's trailing and arcing surface cold
front should sweep E'ward through our CWA from about midday
through this late evening. Behind the cold front, a surface
ridge builds from the Upper Midwest through Tuesday.
A Wind Advisory remains in effect until 12 PM EDT today for Erie
County, PA. Here, a strengthening S'erly low-level jet (LLJ)
through daybreak this morning and mechanical mixing of the
boundary layer tapping into the lower-reaches of the LLJ are
expected to allow SE'erly to SSE'erly downslope surface winds to
gust up to 40 to 50 mph along/near the Lake Erie shore,
especially from roughly daybreak through late morning. In
addition, diurnal convective mixing of the boundary layer
tapping into stronger flow aloft is expected to allow S'erly to
SSW'erly surface winds to gust up to 30 to 40 mph within the
warm sector late this morning through early evening. Behind the
cold front, low-level winds/CAA strengthening with height,
respectively, and resulting steepening of low-level lapse rates
should allow SW'erly to WSW'erly surface winds to gust up to 30
to 40 mph through this early evening and before the boundary
layer begins to stabilize via nocturnal cooling.
Intervals of sunshine/daytime heating and low-level WAA are
expected to allow today's daytime highs to reach the mid 60's
to mid 70's within the warm sector. Behind the cold front,
stabilizing subsidence accompanying the building surface ridge
will result in considerable clearing. Thus, the combination of
nocturnal cooling and low-level CAA will allow overnight lows to
reach the 40's around daybreak Tuesday. Despite mainly clear sky
on Tuesday, weakening CAA downstream of the ridge axis at the
surface and aloft will limit daytime heating. Late afternoon
highs are expected to reach mainly the 60's. However, a weak
synoptic MSLP gradient and sufficient daytime heating of
surface air surrounding ~48F Lake Erie are expected to permit
lake breeze development during the late morning through early
evening. Highs in the lower 50's to lower 60's are expected
along/very near the lakeshore.
As for the remainder of sensible weather, isolated to scattered
showers and thunderstorms are expected to increase in coverage
the rest of this morning as the aforementioned strengthening
LLJ enhances moist isentropic ascent along the upper-reaches of
the warm front and the ascent releases weak to moderate and
solely elevated CAPE. As the warm/moist sector boundary layer
destabilizes via daytime heating later today, the initially
elevated effective inflow layer will become surface-based and
boundary layer CAPE is expected to grow to weak to moderate
magnitudes. Additional organized showers/thunderstorms are
expected along and ahead of the E'ward-advancing cold front late
this morning through evening as low-level convergence and moist
ascent along the cold front, and downshear outflow boundaries
interacting favorably with ambient low-level vertical wind shear
release the aforementioned warm/moist sector boundary layer
CAPE amidst continued moderate to strong effective bulk shear. A
low-level return flow of abundant moisture from the Gulf will
be accompanied by unusually-high PWAT's in/near our CWA, which
will likely allow showers/storms to produce periods of heavy
rainfall. However, flooding concerns are minimal since SW'erly
mean mid-level flow as strong as 40 to 60 knots will result in
fast shower/storm motions, which in turn will limit the duration
of heavy rainfall.
SPC has outlined a marginal risk of severe thunderstorms (risk
level 1 out of 5) in our CWA from roughly Knox County, OH to
Crawford County, PA and points to the southeast. In this area,
greater daytime heating/resulting destabilization of the
warm/moist sector boundary layer should yield steeper low-level
lapse rates and DCAPE values as large as 500 to 750 J/kg amidst
the moderate to strong effective bulk shear. As a result,
multicell and supercell thunderstorms capable of producing
damaging straight-line convective wind gusts are possible. The
severe hail threat appears to be minimal due to the continued
presence of weak mid-level lapse rates and MUCAPE in the hail
growth zone, respectively. Tornado potential also appears to be
minimal since model soundings suggest diurnal convective mixing
of the warm/moist sector boundary layer will limit directional
vertical shear within said layer and thus greatly limit the
magnitude of surface-based ESRH. Once the cold front clears a
given location, showers and storms should end quickly and fair
weather is then expected through nightfall Tuesday evening as
stabilizing subsidence accompanies the aforementioned post-front
ridge.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
The short term forecast period continues to look rather uneventful,
as most of the active weather will be around the forecast area but
not over it. For Tuesday night, high pressure will be over the area
and departing to the east. A warm front will enter the area on the
back side of the surface high for Wednesday. The best moisture and
upper level support continue to be west of the forecast area and
will retain a dry forecast with the warm frontal passage. High
pressure will build back southwest toward the forecast area on
Wednesday night and will keep the area dry. High temperatures on
Wednesday will be a mix of 60s and 70s. The next system will
approach from the west on Thursday. Southerly flow ahead of this
system will continue to pump warmer air into the region and
widespread 70s with some potential for lower 80s will be expected.
However, additional moisture will enter the region and some
isentropic lift could allow for some scattered rain showers to enter
later in the day on Thursday and have PoPs creeping up to a low
chance.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
Unsettled weather continues to be expected for Friday into Saturday,
although the trend is slightly later, as the low pressure system and
cold front are a bit slower. Therefore, have PoPs ramping up through
Friday with the best window for rain on Friday evening and have
categorical PoPs then. The front should clear the forecast area by
Saturday afternoon and have some residual low PoPs through that
time. High pressure will be quick to build in from the west for
Saturday night into Sunday and dry weather will be expected. If the
slowing trend in the late week system continues, then high
temperatures on Friday will be in the 70s. Temperatures would then
fall into the 60s behind the cold front for Saturday and Sunday.
&&
.AVIATION /06Z Monday THROUGH Friday/...
Aloft, SW'erly flow over our region becomes W'erly after
00Z/Tues as one ridge exits toward New England, a disturbance
shifts NE'ward from the Upper MS Valley to northeastern ON
through 06Z/Tues, and a ridge behind the disturbance shifts
from the northern/central Rockies toward the Mid/Upper MS
Valley through 06Z/Tues. At the surface, the disturbance's
attendant low moves NE'ward from the IA/WI/IL border area toward
the ON/QC border, just south of James Bay. This low track will
allow a warm front to sweep NE'ward through our region between
~10Z/Mon and ~19Z/Mon, while an arcing cold front should sweep
E'ward through our region between ~16Z/Mon and ~02Z/Tues. Behind
the cold front, a surface ridge builds from the Mid/Upper MS
Valley region through 06Z/Tues.
Ahead of the warm front, E'erly to SE'erly surface winds around
5 to 15 knots are expected and may gust up to 20 to 25 knots at
times. However, at/near KERI in NW PA and far-NE OH, SE'erly
winds are expected to be as strong as 15 to 25 knots and gust
up to 30 to 40 knots at times between ~09Z/Mon and ~16Z/Mon.
Behind the warm front, our regional surface winds will be S'erly
to SW'erly around 15 to 20 knots and gust up to 25 to 35 knots
at times. Behind the cold front, SW'erly to W'erly winds around
10 to 20 knots, gusting up to 20 to 30 knots, are expected.
The post-cold front winds/gusts are expected to be strongest
prior to 00Z/Tues.
Widespread low/mid/upper-level cloud cover is expected over our
region ahead of the cold front. Ceilings associated with this
cloud cover should tend to be no lower than 5kft AGL. Behind the
cold front, low clouds and resulting ceilings near 5kft AGL are
expected to scatter-out from west to east through 06Z/Tues.
Scattered showers/thunderstorms are expected along/ahead of the
surface warm and cold fronts. Brief MVFR/IFR are expected with
showers and especially storms. Brief/erratic surface wind gusts
up to 40 to 50 knots are possible with thunderstorms behind the
warm front and along/ahead of the cold front.
Outlook...Non-VFR possible with scattered rain showers and
thunderstorms this Thursday afternoon through Friday.
&&
.MARINE...
A complex marine weather day expected today and tonight with low
pressure moving through the heart of the Great Lakes and a cold
front extending across Lake Erie. Ahead of the system, strong
offshore flow is expected to develop. Southeast flow over the
eastern basin will develop with downslope off the higher terrain of
NW PA/W NY and sustained 20 kts or so of wind with gusts of 30 to 35
kts will be expected this morning and will issue a Small Craft
Advisory for this region. Further west, southwest flow will increase
later this morning through the afternoon and evening hours with
sustained winds in the 20 to 25 kt range in offshore flow. This will
expand eastward with time and will issue a separate set of Small
Craft Advisory headlines for this offshore flow. The cold front will
cross the lake by this evening and winds will shift to the west and
slowly decrease. Waves will build up for the eastern half of the
lake tonight into Tuesday and a new Small Craft Advisory will be
needed for the eastern basin. High pressure will build into the
region for Tuesday and flow will become variable at 10 knots or
less. This high will move east for Wednesday, allowing a warm front
to approach the lake and easterly flow will return. This front will
struggle to cross the lake until Friday, when a low pressure system
will move through the Great Lakes region. South to southeast flow
will overtake the lake for Friday.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...Wind Advisory until noon EDT today for PAZ001-002.
MARINE...Small Craft Advisory until 4 AM EDT early this morning for
LEZ142-143.
&&
$$
SYNOPSIS...Jaszka
NEAR TERM...Jaszka
SHORT TERM...Sefcovic
LONG TERM...Sefcovic
AVIATION...Jaszka
MARINE...Sefcovic
Source:
CLE issues Area Forecast Discussion (AFD) at Apr 21, 4:24 AM EDT---------------
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