CLE issues Area Forecast Discussion (AFD) at Jul 31, 1:43 AM EDT ...06z TAF Aviation Forecast Update...125
FXUS61 KCLE 310543
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
143 AM EDT Wed Jul 31 2024
...06z TAF Aviation Forecast Update...
.SYNOPSIS...
Troughing exits our region through this evening as the parent low
moves from near southern Lake Huron toward Lake Ontario. Behind
the low and trough, a ridge builds from the western Great Lakes
through Thursday. By Friday, another trough may overspread our
region from the west.
&&
.NEAR TERM /THROUGH TODAY/...
915 PM Update...
Updated weather grids to insert patchy fog after midnight
across northwest Ohio. Temperatures will dipped to near 70 and
near saturation. Therefore, mist will likely develop but
visibility should remain above 3sm through Wednesday morning.
Otherwise, afternoon package is on track.
Previous Discussion...
Aloft, a shortwave trough exits E'ward from the eastern Great
Lakes and Upper OH Valley through the wee hours of Wednesday
morning, causing mid/upper-level flow to veer from SW'erly to
NW'erly. Simultaneously, the attendant surface low moves from
near southern Lake Huron toward Lake Ontario, which will allow
the associated troughing to exit generally E'ward from our CWA.
Behind the troughing at the surface and aloft, a ridge at the
surface and aloft builds from the western Great Lakes and
vicinity through Wednesday night as predominantly NW'erly
mid/upper-level flow impacts northern OH and NW PA. However,
additional shortwave disturbances should ripple through the
ridge aloft Wednesday through Wednesday night, but exact timing
of the passages of these shortwave disturbances remains
uncertain. A very humid low-level air mass originating over the
Gulf of Mexico lingers in our CWA through Wednesday night
courtesy of the clockwise, outward circulation of a low-level
ridge focused over/near the Gulf of Mexico and southeastern
United States. This same anticyclonic circulation will maintain
low-level WAA across our region. Overnight lows are forecast to
reach mainly the mid 60's to lower 70's around daybreak
Wednesday and Thursday mornings, respectively, as the persistent
low-level warm/moist air advection regime contributes to limited
nocturnal cooling. Intervals of sunshine and daytime heating
are expected to allow highs to reach the 80's to near 90F late
Wednesday afternoon.
Isolated to scattered showers/thunderstorms are expected to exit
our region generally from west to east through the wee hours of
Wednesday morning as surface trough axes revolve around the
surface low and sweep generally E'ward. Odds favor fair weather
through the rest of Wednesday morning due, in part to
stabilizing subsidence accompanying the building ridge.
Additional scattered showers/thunderstorms are expected
Wednesday afternoon through evening as subtle surface trough
axes and associated low-level convergence/ascent traverse our
CWA generally from northwest to southeast in association with
the aforementioned shortwave disturbances. All convection
through Wednesday night is expected to produce periods of
torrential rainfall courtesy of PWAT's exceeding at least the
75th percentile per model guidance and SPC sounding climatology
for the four upper-air stations closest to our CWA.
Simultaneously, boundary layer CAPE is expected to vary from
weak to moderate in magnitude. The greatest instability is
expected late Wednesday morning through early evening, when the
moist boundary layer will destabilize via daytime heating.
Diurnal convective mixing of the boundary layer will yield
steep low-level lapse rates and sizable DCAPE near 500-1000
J/kg. Effective bulk shear is expected to primarily be weak, but
moderate effective bulk shear is expected Wednesday afternoon
through evening, which appears to be the likeliest window when
a stronger shortwave trough will ripple through the ridge aloft
and enhance the isobaric height gradient and therefore flow in
the mid/upper-levels. Given the expected thermodynamic/kinematic
environment Wednesday afternoon and early evening, a few severe
thunderstorms with damaging convective wind gusts are possible,
especially in northern OH.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
Thursday remains another warm and muggy day with dewpoints in the
low 70s. Shortwave ridging aloft will be overhead to start the day
and expect lower coverage of showers with perhaps some subsidence
through midday. By afternoon we may start to see some energy working
back into NW Ohio coupled with theta-e advection so higher chance
pops are focused across southern and western counties during the
afternoon. Mixed layer CAPE of around 1500 J/kg along with some
increase in shear is the reason for a marginal risk of severe
weather per the Storm Prediction Center.
Higher chances of rain are expected Thursday night and likely into
Friday although uncertainty exists in evolution and timing of
convection. A compact upper level trough crosses the Midwest on
Thursday night and reaches western Ohio on Friday. Showers and
thunderstorms will likely increase in coverage Thursday night as a
30 knot low level jet feeds into the area unless convection favors
the higher instability air to the south and disrupts moisture
transport. Some deterministic models show dry air wrapping into the
area on Friday before moisture returns late in the day but expect
that forcing ahead of the trough with broad cyclonic flow at the
surface will result in thunderstorms filling in. Rainfall rates will
remain efficient with this warm and humid airmass and any
thunderstorms will be capable of producing locally heavy rain. High
temperatures will be in the upper 80s again on Thursday with most
areas dropping back into the mid 80s for Friday with greater
coverage of clouds and showers. Overnight low temperatures will be
warm and will struggle to drop below 70 degrees.
&&
.LONG TERM /SATURDAY THROUGH TUESDAY/...
Upper trough axis remains overhead on Saturday with higher chances
of showers and thunderstorms focused generally east of I-71. The
trough will shift south and east of the area on Saturday night with
chances of precipitation decreasing. Surface high pressure builds
into the Ohio Valley on Sunday with humidity levels finally dropping
to more normal values. A broad upper level trough passes north of
the Great Lakes and then deepens across New England Sunday into
Monday. It is a little to soon to say if we may see a few
thunderstorms develop along a trailing frontal boundary on Monday
but will continue with a dry forecast for now given limited
instability and moisture. Temperatures briefly drop back to near
normal values on Monday but will be short lived with highs staring
to warm again by Tuesday.
&&
.AVIATION /06Z Wednesday THROUGH Sunday/...
We are expect mainly VFR conditions for this morning through
this evening. We may see some light, shallow fog with
visibility perhaps down between 3sm and 5sm for a few TAF sites
this morning between 9z and 12z. We have mentioned this
possibility in TEMPO at select sites. There are MVFR ceilings
between 1500 and 3000 feet still lingering around ERI early this
morning. This stratus should lift out and scattered around by
12z or sunrise this morning.
The forecast becomes somewhat uncertain with a low confidence
forecast late this afternoon into this evening. We have chances
for widely scattered convection that could develop with the
afternoon heating across the area. We are not confident enough
to place that potential in any TAFs with timing and coverage at
this time. It will be something we will monitor trends in
forecast guidance and may be something to add with the next TAF
update if needed. Otherwise, we will keep the ceilings VFR for
now through this evening. Winds will be from the southwest or
west 5 to 10 knots today and around 5 knots this evening into
overnight. There will likely be a lake breeze switching the wind
direction from the northwest up to 10 knots during the
afternoon for ERI. We will take another look at CLE where there
also could be a light lake breeze but did not included it in the
TAF with this update.
Outlook...Non-VFR possible in scattered and periodic showers
and thunderstorms Thursday through Sunday.
&&
.MARINE...
Low pressure will pass just north of Lake Erie today with southwest
to westerly winds around 15 knots crossing the central and eastern
portion of Lake Erie early this evening. This will lead to waves
building to 1 to 3 feet. Winds become northwesterly behind the
trough on the east end of Lake Erie tonight with continued choppy
conditions. Occasional thunderstorms are possible during the
Wednesday through Saturday time frame and will impact wind
directions and speeds. Otherwise winds on the lake are generally
expected to be 15 knots or less where thunderstorms do not play a
role.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...None.
&&
$$
SYNOPSIS...Jaszka
NEAR TERM...Jaszka
SHORT TERM...KEC
LONG TERM...KEC
AVIATION...Griffin
MARINE...KEC
Source:
CLE issues Area Forecast Discussion (AFD) at Jul 31, 1:43 AM EDT ...06z TAF Aviation Forecast Update...---------------
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