CLE issues Area Forecast Discussion (AFD) at Aug 18, 1:40 PM EDT148
FXUS61 KCLE 181740
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
140 PM EDT Sun Aug 18 2024
.SYNOPSIS...
Low pressure over lower Michigan will drift east to Lake
Ontario by this evening with a trailing surface trough moving
across the area today. High pressure will build across the area
Tuesday through Thursday before departing to the east coast by
Friday.
&&
.NEAR TERM /THROUGH MONDAY/...
1230 PM Update...
Showers are gradually becoming more widespread this afternoon as
diurnal heating is providing a bit more surface based support.
Overall forcing however remains minimal with overall CAPE values
less than 1000 J/kg and little to no shear present. With little
forcing to produce vertical development of showers, thunder will
be isolated through the afternoon with the greatest chance
between 20-00Z this evening. Aside from that, there were no
changes made with this update.
930 AM Update...
Precipitation this morning remains isolated to the eastern and
central lakeshores of Lake Erie. These showers are expected to
become more widespread through this afternoon with the potential
of thunder increasing. Aside from slightly adjusting PoPs this
morning, no other changes were needed with the forecast at this
point.
Original Discussion...
The cold front continues to move across the area, nearing the
OH/PA state line as its attendant low moves into southern
Ontario this morning. Scattered rain showers accompany the cold
front near the lakeshore in far Northeast Ohio and across
Northwest Pennsylvania this morning. As the low moves east to
near Lake Ontario this afternoon into this evening, a surface
trough rotates around the backside and southward across the area
today. This surface trough will be the focus for the
redevelopment of scattered to numerous showers this afternoon
and evening, when PoPs are maximized around 60-80%. There is
much less instability and nearly no deep- layer shear, so there
should not be a severe or flood threat like yesterday, but there
is enough instability for some embedded isolated to scattered
thunderstorm. For most of the region QPF amounts will be light
with mean QPF amounts of around 0.1-0.25", though locally
higher amounts of up to 0.5" are possible in Northeast Ohio and
Northwest Pennyslvania.
Coverage of precipitation decreases after sunset tonight as the
upper-low continues to depart to the east. Moisture wrapping
around this low, along with cooler temperatures aloft, will
likely transition the precipitation to lake-enhanced light rain
tonight into Monday. Most locations will be fairly dreary and
fall-like on Monday, especially downwind of Lake Erie in
Northeast Ohio and Northwest Pennsylvania where cloud cover will
be greatest and rain chances are highest. Temperatures will also
be quite cool with most of the region in the low to mid 70s, and
even some locations in far Northeast Ohio and NOrthwest
Pennsylvania only staying in the 60s.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Aloft, NW'erly to N'erly flow impacts our CWA Monday night through
Wednesday night as a ridge builds gradually from the northern Great
Plains and vicinity. At the surface, the attendant ridge builds into
our region as the embedded high pressure center moves from near far-
northern ON toward the Upper OH Valley. Fair weather is expected as
stabilizing subsidence accompanies the ridge. This weather pattern
at the surface and aloft will allow a low-level CAA regime, overall,
to impact our CWA. In addition, mainly clear sky, a weak synoptic
MSLP gradient, and low humidity at/near the surface will promote
efficient radiational cooling during the evening through daybreak
hours of Monday night, Tuesday night, and Wednesday night,
respectively. Thus, unusually-cold temperatures are expected.
Overnight lows will reach mainly the 50's around daybreak Tuesday.
Late afternoon highs on Tuesday are forecast to reach only the 60's
in NW PA and the upper 60's to mid 70's in northern OH. Tuesday
night is expected to be cooler, with lows forecast to reach mainly
the upper 40's to mid 50's around daybreak Wednesday morning.
Wednesday's late afternoon highs are expected to reach the upper
60's to lower 70's in NW PA and the lower to mid 70's in northern
OH. Wednesday night is expected to feature lows reaching mainly the
upper 40's to mid 50's around daybreak Thursday morning.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
The aforementioned ridge aloft is expected to continue to build
gradually from the north-central United States and vicinity during
this period. At the surface, the attendant ridge continues to affect
our CWA as the embedded high pressure center migrates from near the
Upper OH Valley toward the southern Appalachians. Fair weather is
expected to persist courtesy of stabilizing subsidence accompanying
the ridge. The aforementioned evolution of the ridge at/near the
surface will allow net low-level WAA to take hold across our region.
This factor combined with daytime heating will allow late afternoon
highs to moderate from the mid to upper 70's on Thursday to
widespread 80's on Saturday. Overnight lows should reach mainly the
50's around daybreak Friday and mainly the mid 50's to mid 60's
around daybreak Saturday.
&&
.AVIATION /18Z Sunday THROUGH Friday/...
Most terminals have rebounded to VFR conditions this afternoon
with scattered ceilings ranging from 1-2kft. Isolated terminals
across NE OH, including KYNG, continue to be impacted by
MVFR/IFR ceilings, which should gradually improve this afternoon
to allow for a period of VFR. Looking at radar, scattered
showers have begun to develop across the area and are expected
to continue through the evening. These showers have the
potential to produce heavy rainfall, which may briefly lower
visibilities at terminals they impact. In addition, a rumble or
two of thunder cannot be ruled out, but given a lack of
instability and shear to maintain any storms that develop not
expected anything widespread. Given the scattered nature of
convective potential this afternoon, opted to handle the mention
of thunderstorm potential and diminished conditions in a TEMPO
primarily from 20-00Z. After sunset, any lingering thunder
potential will dwindle, leaving scattered showers primarily
across the eastern terminals.
Overnight, KTOL should remain VFR as the axis of the trough
shifts east. However, all other terminals will linger in the
MVFR to IFR range as lower ceilings once again settle across the
area. Highest confidence in IFR ceilings is at KMFD, KCAK, and
KYNG. Conditions will gradually begin to improve from west to
east on Monday for most terminals with the potential of light
showers lingering across the typical snowbelt areas.
Winds this afternoon will persist from the northwest at 5-10
knots, gradually becoming northerly by 04Z tonight. These winds
will quickly ramp up by Monday morning, increasing at all
terminals to 10-12 knots with sustained winds up to 15 knots
possible for terminals along the lakeshore. By late morning,
wind gusts of 20-25 knots are possible with the strongest gusts
expected at KERI and KCLE.
Outlook...Non-VFR possible in showers and thunderstorms through
Monday mainly in the afternoon and early evening. Widespread
non-VFR appears most likely in low ceilings Sunday night into
Monday.
&&
.MARINE...
Small Craft Advisory and Beach Hazards Statement in effect from 8 PM
EDT this evening to 4 AM Tuesday from Maumee Bay to The Islands.
Farther east, a Small Craft Advisory and Beach Hazards Statement are
in effect from The Islands to Conneaut from 8 PM this evening to 5
PM Tuesday. An occluded low will drift from southern Lake Huron to
eastern Lake Ontario through Monday morning. This will allow the
trailing cold front over western Lake Erie early this morning to
drift E'ward and clear the rest of Lake Erie by midnight Monday
morning. Behind, the front, a trough lingers over Lake Erie through
Monday morning. Later Monday through Thursday, a ridge builds
gradually from the Upper Midwest and vicinity. Note: Waterspouts are
possible through Monday, especially along the cold front and post-
front surface trough axes.
The aforementioned cold front passage will cause SW'erly winds to
veer gradually to NNW'erly through tonight. Winds are expected to be
around 10 to 15 knots over the eastern basin, where waves will
remain 3 feet or less. Farther west, winds around 10 to 15 knots
freshen to around 15 to 25 knots this evening and overnight tonight
as the lingering trough interacts with the aforementioned ridge.
Accordingly, waves of 3 feet or less today build to as large as 3 to
6 feet this evening and overnight tonight. On Monday, NNW'erly to
N'erly winds around 15 to 25 knots and waves as large as 3 to 6 feet
persist over western and central Lake Erie. Over the eastern basin,
NNW'erly to N'erly winds are expected to freshen to 15 to 20 knots.
In response, waves of 1 to 3 feet with occasional 4 footers are
expected and a Small Craft Advisory/Beach Hazards Statement will
eventually be needed between Conneaut and Ripley. N'erly to NNE'erly
winds around 15 to nearly 25 knots are expected Monday night basin-
wide. Waves will remain as large as 3 to 6 feet, especially in the
central basin, where fetch will be maximized.
N'erly to NNE'erly winds are expected to ease gradually to 10 to 15
knots on Tuesday, which will allow waves to subside to 3 feet or
less by sunset Tuesday evening. Winds become variable in direction
and ease further to around 5 to 10 knots Tuesday night through
Thursday in response to the aforementioned building ridge. This will
allow waves to subside further to 2 feet or less by sunrise
Wednesday morning.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Beach Hazards Statement from 8 PM EDT this evening through
late Monday night for OHZ003-007.
Beach Hazards Statement from 8 PM EDT this evening through
Tuesday afternoon for OHZ009>012-089.
PA...None.
MARINE...Small Craft Advisory from 8 PM this evening to 4 AM EDT
Tuesday for LEZ142-143.
Small Craft Advisory from 8 PM this evening to 5 PM EDT
Tuesday for LEZ144>148.
&&
$$
SYNOPSIS...Saunders
NEAR TERM...Campbell/Saunders
SHORT TERM...Jaszka
LONG TERM...Jaszka
AVIATION...Campbell
MARINE...Jaszka
Source:
CLE issues Area Forecast Discussion (AFD) at Aug 18, 1:40 PM EDT---------------
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