CLE issues Area Forecast Discussion (AFD) at Aug 19, 6:20 AM EDT684
FXUS61 KCLE 191020
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
620 AM EDT Mon Aug 19 2024
.SYNOPSIS...
A trough exits gradually eastward from northern Ohio and
northwest Pennsylvania through Tuesday as a ridge builds from
the Upper Midwest. 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 TUESDAY/...
6:20 AM EDT Update...
Forecast remains valid per latest trends in obs and model
guidance. No changes appeared necessary.
Previous Discussion...
Aloft, cyclonic W'erly to NW'erly flow and embedded shortwave
disturbances affect our region through Tuesday as a trough axis
drifts E'ward from the eastern Great Lakes and Upper OH Valley
toward northeastern NY and the Delmarva Peninsula, and a ridge
attempts to build from the northern/central Great Plains. At
the surface, a trough exits E'ward gradually as a ridge builds
from the Upper Midwest and vicinity. This pattern will maintain
a net low-level CAA regime and unusually-cold air mass across
our CWA. A sufficiently-moist northerly mean low-level flow
over/downwind of Lake Erie and 850 mb temperatures falling from
near 12C to near 6C over the ~24C lake surface during the near-
term period will allow scattered to widespread lake-effect
stratocumulus clouds to continue to stream generally S'ward from
the lake. Lake-effect cloud coverage is expected to be greatest
this morning and again late this evening through Tuesday
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 Tuesday as convective
temperatures are easily reached or breached. Isolated lake-
enhanced/effect rain showers over and generally south of Lake
Erie are expected to end by this early evening as lake-induced
CAPE wanes via low-level dry air advection and a lowering
subsidence inversion, and plummeting mid-level moisture causes
the seeder-feeder process to end by sunrise or so this morning.
Fair weather is expected during the rest of the near-term
period as the stabilizing subsidence inversion accompanying the
aforementioned ridge continues to lower/strengthen.
Given the net low-level CAA regime and expected evolution of cloud
cover in our CWA, expect today's late afternoon highs to reach only
the 60's to 70F in NW PA, the upper 60's to lower 70's in NE OH, and
the lower to mid 70's farther west. Tonight's lows should reach
mainly the 50's around daybreak Tuesday morning. However, lows are
expected to reach the upper 40's in the interior valleys of NW PA.
Tuesday's late afternoon highs will be slightly cooler. Widespread
60's are expected in NW PA. Highs are forecast to reach the mid 60's
to 70F in NE OH and the upper 60's to lower 70's farther west.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
An upper-level low move south across the eastern Great Lakes Tuesday
night before slowly moving east through the rest of the short term
period. There is some variance but most model guidance has decent
moisture around 850mb, which when paired with cold air aloft (and
thus some modest lake-induced instability), should result in some
light rain showers in parts of Northwest Pennsylvania, and scattered
to broken cloud cover downwind of Lake Erie Tuesday night and
possibly into Wednesday. This upper-low will only act to reinforce
the cold airmass and below normal temperatures, so expect chilly
temperatures to continue Tuesday night through Wednesday night.
Surface high pressure should build in by Thursday with temperatures
beginning to rebound Thursday and Thursday night (although still
below normal).
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
High pressure will depart to the east coast through the weekend,
with temperatures rebounding back to the 80s by Saturday and Sunday.
Precipitation is unlikely during the long term period as an upper-
level ridge gradually builds in from the west.
&&
.AVIATION /12Z Monday THROUGH Friday/...
W'erly to NW'erly flow aloft and embedded disturbances affect
our region through 12Z/Tues. At the surface, a trough exits
very slowly E'ward as a ridge builds from the Upper Midwest. Our
regional surface winds will vary between NW'erly and NNE'erly
around 5 to 15 knots. Gusts up to 20 knots or so are expected at
times, especially between ~14Z and ~22Z/Mon.
Lake-enhanced/effect rain showers over and generally south of
Lake Erie are expected to end gradually from west to east
through ~22Z/Mon. Brief MVFR visibility is possible in precip
through ~15Z/Mon. Otherwise VFR visibility is expected.
Scattered to broken low cloud bases are expected to be mainly in
the 2kft to 5kft AGL range through the TAF period. However,
pockets of IFR ceilings are expected through ~14Z/Mon,
especially in interior northeast and north-central OH, including
at KMFD, KCAK, and KYNG.
Outlook...VFR and fair weather likely Tuesday through Friday.
&&
.MARINE...
Strong north to northwest flow of 15 to 25 knots continues through
at least Tuesday afternoon. Small craft advisory and beach hazard
statements remain unchanged with this forecast update, although it's
possible that some of these headlines may need to be extended into
the Tuesday evening or early Tuesday night. Flow continues into
Wednesday, although should be much weaker (~10-15 knots). High
pressure builds in by Thursday.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Beach Hazards Statement through late tonight for OHZ003-007.
Beach Hazards Statement through Tuesday afternoon for
OHZ009>012-089.
PA...Beach Hazards Statement through Tuesday afternoon for PAZ001.
NY...None.
MARINE...Small Craft Advisory until 4 AM EDT Tuesday for LEZ142-143.
Small Craft Advisory until 5 PM EDT Tuesday for LEZ144>149.
&&
$$
SYNOPSIS...Jaszka
NEAR TERM...Jaszka
SHORT TERM...Saunders
LONG TERM...Saunders
AVIATION...Jaszka
MARINE...Saunders
Source:
CLE issues Area Forecast Discussion (AFD) at Aug 19, 6:20 AM EDT---------------
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