CLE issues Area Forecast Discussion (AFD) at Aug 20, 1:43 PM EDT206
FXUS61 KCLE 201743
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
143 PM EDT Tue Aug 20 2024
.SYNOPSIS...
A trough exits gradually eastward from northern Ohio and northwest
Pennsylvania today as a ridge builds from northern Ontario and the
Upper Great Lakes. This ridge is expected to continue to affect our
region on Wednesday through this weekend as the embedded high
pressure center wobbles southeastward from the western Great Lakes
toward the Carolinas.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
12:30 PM Update...
The forecast remains on track this afternoon with no changes.
9:30 AM Update...
Increased cloud cover slightly over the next few hours in north
central and NE Ohio into NW PA to account for the lake-effect
clouds. These should gradually dissipate this afternoon as
strong Canadian high pressure continues to build southeastward
from the Upper Midwest, so the rest of the forecast remains on
track.
6:19 AM EDT Update...
Forecast remains valid per latest trends in obs and model
guidance. No changes appeared necessary.
Previous Discussion...
Aloft, cyclonic NW'erly to N'erly flow and embedded shortwave
disturbances affect our region through Wednesday as a low
wobbles SE'ward from southwestern QC toward northern New England
and a ridge attempts to build from the northern/central Great
Plains. At the surface, a trough continues to exit E'ward from
our CWA as a ridge continues to build gradually from the Upper
Great Lakes. This pattern will maintain primarily low-level CAA
and an unusually-cold air mass across our region. A sufficiently-
moist mean low-level flow, varying between NNE'erly and NW'erly
over/downwind of Lake Erie, and 850 mb temperatures near 4C to
6C over the ~24C lake surface will allow scattered to widespread
lake-effect stratocumulus clouds to continue to stream from the
lake and across most or all of our CWA. Lake-effect cloud
coverage is expected to be greatest this morning and again late
this evening through Wednesday morning, when Lake Erie will be
the primary source of warmth, moisture, and instability. In
addition, model soundings in BUFKIT are in good agreement that
widespread cumulus clouds will develop via daytime heating
during the late morning through early evening hours of today and
Wednesday as convective temperatures are reached or breached
easily. There is a 20% chance for isolated and very light lake-
effect rain showers to impact locations generally south of Lake
Erie through this early evening. Thereafter, fair weather is
expected during the rest of the near-term period due to the
following: Continued low-level dry air advection; a lowering,
strengthening, and stabilizing subsidence inversion accompanying
the aforementioned ridge; the two aforementioned processes
causing weak lake-induced CAPE to wane further.
Given the expected temperature advection regime and evolution of
cloud cover in our CWA, expect today's late afternoon highs to reach
only the 60's in NW PA, the mid 60's to 70F in NE OH, and the upper
60's to lower 70's farther west. Partial clearing, light or calm
surface winds, and limited humidity at/near the surface will promote
efficient radiational cooling this evening through daybreak
Wednesday morning, when low temperatures are forecast to reach
mainly the mid 40's to mid 50's. The coolest readings will be found
inland from Lake Erie. Wednesday's late afternoon highs are expected
to reach the 60's in NW PA, the upper 60's to lower 70's in NE OH,
and the lower to mid 70's farther west.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
Surface high pressure builds in by Thursday before departing to
east, while upper-level ridging gradually builds in through the
short term period. This will result in quiet weather conditions with
rebounding temperatures. Should see highs back to near normal by
Friday.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
Fairly steady-state synoptic pattern exists in the long term with
surface high pressure over the east coast and upper-level ridging
over the central CONUS. Locally, mid-level height rises are expected
with gradually rising surface temperatures. Above normal
temperatures are expected areawide Saturday through Monday (and
probably beyond). It's possible that a weak shortwave moves
southeast along the outer edge of the upper-level ridge, though
there is low confidence. Currently only have PoPs in the 5-15% range
Saturday onward.
&&
.AVIATION /18Z Tuesday THROUGH Sunday/...
VFR will prevail through the TAF cycle as high pressure
currently centered over the Upper Midwest builds across the
central Great Lakes. Scattered broken 5,000 to 10,000 foot
clouds will become mostly clear tonight as the drier air and
subsidence work in.
N winds of 10-15 knots will gust to 20-25 knots this afternoon
before turning light and variable tonight. Lighter N winds of
5-10 knots are then expected Wednesday.
Outlook...Fair weather and VFR expected Wednesday through
Sunday.
&&
.MARINE...
Currently past the peak strength of wind speeds over Lake Erie and
should see things gradually ramp down today and tonight as high
pressure builds in from the west. For now, have allowed the western
portion of the small craft advisory and beach hazard statement
expire at 4 AM, with the rest of headlines through this afternoon
and tonight. As high pressure builds in, should continue to see
improving conditions across Lake Erie on Wednesday and Thursday.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Beach Hazards Statement until 5 PM EDT this afternoon for
OHZ009-010-089.
Beach Hazards Statement through late tonight for OHZ011-012.
PA...Beach Hazards Statement until 5 PM EDT this afternoon for
PAZ001.
NY...None.
MARINE...Small Craft Advisory until 5 PM EDT this afternoon for LEZ144-
145-148-149.
Small Craft Advisory until 2 AM EDT Wednesday for LEZ146-147.
&&
$$
SYNOPSIS...Jaszka
NEAR TERM...Garuckas/Jaszka
SHORT TERM...Saunders
LONG TERM...Saunders
AVIATION...Garuckas
MARINE...Saunders
Source:
CLE issues Area Forecast Discussion (AFD) at Aug 20, 1:43 PM EDT---------------
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