CLE issues Area Forecast Discussion (AFD) at Aug 11, 10:08 PM EDT944
FXUS61 KCLE 120208
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
1008 PM EDT Sun Aug 11 2024
.SYNOPSIS...
A trough will drop southeast across the region tonight before
high pressure builds in from the southwest Monday and Monday
night. Low pressure approaches towards the end of this week.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
10:08 PM EDT Update...
Most of forecast remains valid per latest trends in obs and
model guidance. Only change was to increase coverage of lake-
enhanced/effect showers and thunderstorms and QPF of at least
0.01" over and generally east-southeast of central and eastern
Lake Erie through the predawn hours of Monday morning based on
latest trends in obs, higher-res forecast model guidance, and
expectation of another shortwave disturbance and attendant
surface trough axis to sweep SE'ward across the lake very late
this evening through the wee hours of Monday morning. This
surface trough axis will encounter moderate to strong lake-induced
CAPE and lake-induced equilibrium levels near 30kft AGL amidst
WNW'erly to NW'erly mean low-level flow and WNW'erly mean mid-
level flow. Behind the surface trough axis, a few lake-effect
showers/thunderstorms remain possible over and generally
southeast of central and especially eastern Lake Erie through
about daybreak as a similar thermodynamic environment persists
over the ~24C lake and mean flow in the low-level and mid-level
atmospheric column, respectively, becomes NW'erly/well-aligned
behind the shortwave disturbance's axis. Please see discussion
below for further details.
Previous Discussion...
A longwave trough is digging into the northeast tonight into
Monday. One last little embedded upper- level shortwave trough
and associated surface reflection will drop southeast across
Lake Erie and adjacent northeast OH and northwest PA overnight
tonight. The longwave trough will begin shifting east by Monday
night, allowing surface high pressure to build in from the
southwest. As this happens, a flat shortwave (with no surface
reflection) will enter the region from the west Monday night.
A mainly dry near term forecast period is expected. Daytime
heating beneath the trough aloft is allowing scattered showers
and storms from southern Ontario across Lake Erie into far
northeast OH and northwest PA this afternoon. This activity
should shift east-southeast and dissipate towards sunset this
evening with diurnal cumulus elsewhere also dissipating with
sunset. However, as Lake Erie becomes the primary heat and
moisture source overnight some lake effect showers will remain
possible from far northeast OH into northwest PA, especially as
the final shortwave and surface trough drop through. Outside of
a few lingering showers in northwest PA we should be dry on
Monday. Did introduce a slight chance (20%) chance of showers
Monday night ahead of the next shortwave. While surface high
pressure will be dominant, modest lift, moisture, and
instability (especially near Lake Erie overnight) may contribute
to a few showers as several hi-res models indicate.
Lows tonight will once again settle into the 50s and lower 60s.
Highs on Monday will tick up a bit, generally into the upper 70s
and lower 80s, with low to mid 70s in PA. Lows Monday night will
generally range from the mid 50s to lower 60s, slightly milder
than tonight.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Base of the upper trough will be to the east of the local area by
the start of the short term as an upper ridge begins to build over
the Mississippi Valley. Upper shortwave moving along the upper trough
may allow for scattered showers and thunderstorms to develop Tuesday
afternoon and evening before the high builds in for Wednesday.
Broad northwesterly flow will keep temperatures a few degrees below
normal with highs in the upper 70s and lows in the upper 50s on
Tuesday and Tuesday night respectively. High temperatures approach
normal values Wednesday as they rise into the lower 80s with
overnight lows Wednesday night settling in the upper 50s to lower
60s.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
More active period comes later this week and into the weekend as an
upper low over the Upper Midwest glides east into the Great Lakes
region. At the surface, low pressure will lift a warm front east
across the Ohio Valley Friday before swinging a cold front on
Saturday. Still some uncertainty on timing but shower and
thunderstorm chances will increase Thursday night into the weekend.
Expect seasonable temperatures with highs in the low/mid 80s and
overnight lows in the low 60s. Humidity returns by the end of the
week as dew points rise into the mid/upper 60s for the weekend.
&&
.AVIATION /00Z Monday THROUGH Friday/...
At the surface, a trough over our region exits E'ward very
gradually through 00Z/Tues as ridge builds from the Mid/Upper MS
Valley and vicinity. Our regional surface winds are expected to
be around 5 to 15 knots and vary between WSW'erly and NW'erly.
Mainly VFR and fair weather are expected. However, isolated
lake-enhanced/effect rain showers/thunderstorms with brief MVFR
are expected over central/eastern Lake Erie, far-NE OH, and NW
PA through about 12Z/Mon. These showers/storms are expected to
move generally E'ward or SE'ward.
Outlook...Periods of isolated to scattered showers/thunderstorms
with non-VFR are possible Monday night through Tuesday and
Thursday afternoon through Friday.
&&
.MARINE...
Small Craft Advisory and Beach Hazard Statement for Avon Point OH
to Ripley NY (Cuyahoga Co. to Erie Co. PA) remains in effect through
early Monday morning. Surface troughing has allowed for west to
northwest winds to remain elevated between 15-20 knots with wave
heights of 3-6 feet. Surface trough exits Monday morning as surface
high pressure builds over the lake and will bring quieter marine
conditions by late Monday. High pressure remains over the region
through mid-week with no marine headlines anticipated through
mid-week.
Given the seasonably-cool airmass across the region, the waterspout
potential will likely remain over the lake into Monday
afternoon.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Beach Hazards Statement until 4 AM EDT Monday for OHZ089.
PA...Beach Hazards Statement until 4 AM EDT Monday for PAZ001.
NY...None.
MARINE...Small Craft Advisory until 4 AM EDT Monday for LEZ148-149.
&&
$$
SYNOPSIS...Sullivan
NEAR TERM...Jaszka/Sullivan
SHORT TERM...Iverson
LONG TERM...Iverson
AVIATION...Jaszka
MARINE...Iverson
Source:
CLE issues Area Forecast Discussion (AFD) at Aug 11, 10:08 PM EDT---------------
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