CLE issues Area Forecast Discussion (AFD) at Sep 7, 1:34 AM EDT
752
FXUS61 KCLE 070534
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
134 AM EDT Sat Sep 7 2024
.SYNOPSIS...
A cold front sweeps southeastward through our region through this
early evening. Behind the front, a trough lingers over and near
the eastern Great Lakes through Saturday as a ridge noses into
the Ohio Valley from the north-central United States and vicinity.
This ridge is expected to build into our entire region from the
Upper Midwest this Sunday through at least midweek.
&&
.NEAR TERM /THROUGH TODAY/...
9:30 PM Update...
The forecast overnight remains on track with no changes. The
steadiest showers should exit far NE Ohio and NW PA by 06Z with
a lull in the rain until strengthening cold air advection and
wraparound moisture kicks in lake-effect showers late tonight
and Saturday morning. This will produce frequent showers over
favored upslope areas of north central and NE Ohio and NW PA
given the 310-330 degree boundary layer flow. See original
discussion for details.
6:30 PM Update...
Increased PoPs across NE Ohio and NW PA over the next 6 to 8
hours as the cold front slowly crosses the region with abundant
coverage of light to occasionally moderate rain. This is driven
by strengthening frontogenetic forcing as a 90-100 knot H3 jet
rounding the base of the digging mid/upper trough enters the
southern Great Lakes and the front's forward progress is slowed
by the trough closing off, so feel that the steadiest showers
will take some time to end this evening and early tonight. The
rest of the forecast remains on track for tonight and Saturday.
Original Discussion...
Aloft, a trough axis moves ESE'ward from the northern Great
Lakes and Upper MS Valley to central Lake Ontario and central PA
by nightfall Saturday evening, which will cause cyclonic SW'erly
flow to veer to NW'erly over our CWA. At the surface, the
attendant cold front extended SW'ward from near the Lake Erie
Islands to just east and south of Indianapolis as of 3:45 PM EDT
this afternoon. This front will continue moving SE'ward and is
still expected to exit our CWA by ~8 PM EDT this evening. Pre-
front trough axes ahead of the front will continue moving E'ward
and are expected to exit our CWA to the east by ~6 PM EDT this
evening. Behind the front, a ridge begins to nose into the OH
Valley from the north-central United States through Saturday as
a trough lingers over/near the eastern Great Lakes. A much
colder air mass overspreads our region behind the front. Low-
level CAA will contribute to overnight lows reaching mainly the
upper 40's to mid 50's by daybreak Saturday. Late afternoon
highs on Saturday are expected to reach only the upper 50's to
lower 60's as continued strong low-level CAA greatly limits
daytime heating via peeks of sunshine.
Low-level convergence/ascent along the front and pre-front
trough axes will continue to trigger isolated to scattered
showers and thunderstorms over northern OH and NW PA, especially
in our north-central OH counties and points farther east, as
the forcing for ascent coincides with moderate effective bulk
shear, sufficient low-level moisture, and weak to moderate
boundary layer CAPE in the warm sector. A few severe
thunderstorms with damaging convective wind gusts remain
possible through this early evening from roughly Erie County, PA
to Knox County, OH and farther east, where greater diurnal
convective mixing of the boundary layer has yielded greater
boundary layer CAPE, steeper low-level lapse rates, and DCAPE
near 500-1000 J/kg. Weak mid-level lapse rates will greatly
curb severe hail potential.
Behind the cold front, fair weather is expected to impact our
I-75 corridor counties and vicinity through Saturday as
stabilizing subsidence accompanies the aforementioned low-level
ridge. Farther east, scattered lake-effect showers and isolated
thunderstorms are expected as 850 mb temperatures drop to near
3C to 5C over ~23C Lake Erie, lake-induced CAPE grows to
moderate to large magnitudes, low-level moisture remains
sufficient, and NW'erly to N'erly mean low-level flow occurs
over and downwind of Lake Erie.
Aloft, cyclonic NW'erly flow persists Saturday night as the
aforementioned trough exits slowly E'ward and a ridge attempts
to build from the northern Rockies and northern Great Plains. At
the surface, the trough weakens over/near the eastern Great
Lakes as the aforementioned ridge attempts to build into our
entire CWA from the Upper Midwest and vicinity. Primarily fair
weather is expected. Lingering and isolated lake-effect rain
showers/thunderstorms over and generally southeast of Lake Erie
are expected to end by the wee hours of Sunday morning as lake-
induced CAPE wanes via low-level dry air advection from the
north and west, and a lowering subsidence inversion accompanying
the ridge. Net low-level CAA will contribute to overnight lows
reaching mainly the lower 40's to lower 50's around daybreak
Sunday.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/...
The short term forecast period will be a transitional period with an
upper trough and associated surface low moving east out of the
region and surface high pressure building from the west. Northwest
flow and cold air advection will continue across the region on
Sunday. A rather dry air mass will be in place and will limit
overall potential for lake effect rain showers but there should be
enough moisture from the lake and instability to at least allow for
some clouds on Sunday. The cold flow will keep temperatures well
below normal with highs in the 60s. The trough axis will be east of
the area on Monday and subsidence with the advancing high pressure
system and continued dry air should allow for a dry forecast.
Backing flow will allow for temperatures to increase on Monday
temperatures will be in the 70s to near 80 degrees.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
The long term forecast period can be simply stated as warm and dry.
Surface high pressure will shift east of the area on Tuesday and an
upper ridge will enter overhead, potentially turning into an upper
level high. This pattern will allow for return flow and warm air
advection into the region. The ridge aloft will offer subsidence to
keep the period dry. Temperatures will start in the low to mid 80s
and increase a couple degrees each day through Friday.
&&
.AVIATION /06Z Saturday THROUGH Wednesday/...
Mixed-bag of VFR, MVFR, and IFR across the TAF sites early this
morning, associated with low ceilings. For the most part, low-
end VFR ceilings (~3.5kft) will be favored through the TAF
period, with the highest confidence of non-VFR at ERI in
persistent lake-effect clouds and rain. Non-VFR vsbys will
remain possible at TAF sites downwind of Lake Erie
(CLE/CAK/YNG) in lake-effect rain showers, though any
restrictions should be brief.
Winds are generally out of the north to northwest early this
morning, around 10 knots. Winds will persist out of the
northwest today, increasing to 10 to 15 knots with gusts of 20
to 25 knots possible by this afternoon.
Outlook...Lingering non-VFR possible in lake-effect rain/clouds
across far NE OH/NW PA on Sunday. Otherwise, mainly VFR is
expected through Wednesday.
&&
.MARINE...
A cold front is moving across Lake Erie this afternoon and will be
southeast of the lake tonight. Winds will be shifting to the west
then northwest behind the front and increasing tonight. Winds should
reach the 15 to 25 kt range and waves will respond to 4 ft or
greater and will retain the Small Craft Advisories and Beach Hazards
Statements for tonight through Sunday. With cold air advection over
the lake, there will be some lake enhanced rain with favorable
conditions for water spouts and will main the water spout mention in
the forecast and hazardous weather outlook. Winds will shift to the
west with high pressure building into the area early next week. A
strong enough pressure gradient will be present for enhanced
westerly flow on Sunday and the Small Craft Advisory for the eastern
half of the lake may need to be extended. High pressure will be over
the region for most of next week and light southwest flow will be
favored on Monday and Tuesday.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Beach Hazards Statement through this evening for OHZ003-007.
Beach Hazards Statement through Sunday morning for OHZ009-010.
Beach Hazards Statement through Sunday evening for OHZ011-012-
089.
PA...Beach Hazards Statement through Sunday evening for PAZ001.
NY...None.
MARINE...Small Craft Advisory until 8 PM EDT this evening for LEZ142-
143.
Small Craft Advisory until 8 AM EDT Sunday for LEZ144-145.
Small Craft Advisory until 8 PM EDT Sunday for LEZ146>149.
&&
$$
SYNOPSIS...Jaszka
NEAR TERM...Garuckas/Jaszka
SHORT TERM...Sefcovic
LONG TERM...Sefcovic
AVIATION...Kahn
MARINE...Sefcovic
Source: CLE issues Area Forecast Discussion (AFD) at Sep 7, 1:34 AM EDT (https://mesonet.agron.iastate.edu/p.php?pid=202409070534-KCLE-FXUS61-AFDCLE)
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