CLE issues Area Forecast Discussion (AFD) at Aug 28, 7:21 AM EDT350
FXUS61 KCLE 281121
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
721 AM EDT Wed Aug 28 2024
.SYNOPSIS...
A weak cold front extending from low pressure over Canada will
settle south across the area today. This front will stall near the
Ohio Valley on Thursday before lifting back north as a warm front on
Friday. Low pressure will pass north of the Great Lakes with a
stronger cold front settling south across the area Friday night.
&&
.NEAR TERM /THROUGH THURSDAY/...
Scattered showers with a few thunderstorms continue to move
northeast across the area this morning. This activity is likely
to diminish through the morning with clouds thinning. The degree
of clearing will impact both the temperature forecast and degree
of destabilization. Models soundings show some degree of a cap
remaining today so uncertainty remains in regards to amount and
degree of additional thunderstorms.
Previous discussion...
Active weather remains possible today as a trough crosses the Upper
Great Lakes and flattens the ridge axis south across the area. Low
pressure has moved into southern quebec with a cold front extending
westward across Central Lower Michigan. With the front still to
the north, moisture continues to advect into the region today,
interacting with a southward moving cold front, and potential
for additional showers and thunderstorms. The airmass remains
hot with humidity values higher than yesterday, but also
expecting varying degrees of cloud cover and thunderstorms to
develop this afternoon so it will be hard to achieve the 100
degree heat index values needed for an Advisory. It will be
close in several of our southern counties if precipitation takes
until late in the day. Overall pattern has too many items that
could limit temperatures today so did not issue a Heat Advisory
at this time.
The challenge for later today revolves around timing and
coverage of showers and thunderstorms. Moisture advection will
continue today with a ribbon of high theta-e air in place
across the area. Light showers with a few embedded thunderstorms
have spread northeast across the area this. This is expected to
wane this morning with the question becoming where and when
additional thunderstorms develop this afternoon. It may take
until the front settles south into the area between 18-23Z for
scattered showers and thunderstorms to develop. Convection could
fire with convergence along the front or a remnant outflow
boundary from the morning activity. Differential heating
boundaries may also come into play with varying degrees of
cloud cover. Another option is a stronger complex of
thunderstorms moving out of Indiana towards Central Ohio later
today which could impact southern counties or miss us entirely.
In general, a broad 30-50 pop is in the forecast for today with
some limiting factors. CAPE values of 1500-2000 J/kg are
possible for areas that experience more sun. A slight risk of
severe thunderstorms is in place for most of the area with 25
knots of shear and moderate instability. Heavy rain will also be
a concern given the moisture rich airmass and high rainfall
rates, especially if any training occurs.
Cold advection will increase behind the front tonight as high
pressure builds to the north. Highs on Thursday are forecast to be
closer to normal in the low to mid 80s. We don't really lose the
higher boundary layer moisture with dewpoints still forecast to
be near 70 degrees. Residual instability remains on Thursday
and added a low pop into the forecast where there is a little
better surface convergence in the east.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
A warm front will lift northeast across the area Thursday night into
early Friday. Not much forcing, but there may be just enough warm
air and moisture advection with the front to support a few showers
or storms. Introduced slight chance (20%) POPs Thursday night as a
result. We'll break into the open warm sector on Friday, leading to
a dry first several hours of the day. A cold front will begin
approaching from the northwest late in the day and the atmosphere
ahead of the front will become weakly to moderately unstable thanks
to strong heating of a fairly moist low-level airmass. For these
reasons have 30-40% POPs across most of the area for the mid-
afternoon to early-evening timeframe on Friday. The cold front and
better jet support sweep through Friday night, so have the highest
POPs (in the 60-80% range) Friday night. The front will not clear
our southeastern counties until Saturday afternoon and has trended a
bit slower in recent model runs, so linger 30%+ POPs into Saturday
southeast of a Sandusky to Findlay line, with likely wording (60%+)
from near Mt Vernon to Akron to North East, PA points southeast. Dry
weather sweeps into our entire area from the northwest by later
Saturday afternoon as the front finally exits. Poor mid-level lapse
rates, weak shear, and unfavorable diurnal timing of the front argue
against a severe weather risk Friday afternoon and evening. However,
don't want to entirely rule out isolated gusty winds/heavy rain.
After lows generally in the mid to upper 60s Thursday night one more
hot day is in store for Friday. 850mb temperatures climbing to 20-
22C and what should be a decent amount of sunshine through at least
the early afternoon will support high temperatures in the mid to
upper 80s in northwestern PA and far northeastern OH and in the low
to mid 90s elsewhere across northern Ohio. Dew points ranging from
the mid 60s to near 70 at peak heating will support peak heat index
values in the mid to upper 90s across much of northern Ohio, cooling
to the low to mid 90s in far northeastern OH and into PA. Values the
last several forecast cycles have been consistently just below the
100 degree advisory criteria, though aren't far off. Lows Friday
night will fall into the 60s with highs on Saturday cooling a good 7
to 10 degrees from Friday, generally in the low to mid 80s with
perhaps some upper 70s in PA. Lows Saturday night are expected to
range from the upper 50s in some outlying areas to the mid 60s.
&&
.LONG TERM /SUNDAY THROUGH TUESDAY/...
An upper trough will dig into the Northeast Sunday into Monday
before beginning to start lifting out on Tuesday. A secondary cold
front will cross late Sunday into Sunday night as the trough digs
in. A decent Canadian high pressure for this early in the season
will follow for Monday and Tuesday. Have some 20-30% shower chances
in late Sunday into Sunday night with the secondary front, highest
near the eastern lakeshore. Otherwise, dry and mainly clear
conditions can be expected for the long term. Temperatures will be
cooler than normal, especially Monday and Tuesday. A number of areas
away from the lakeshore and larger urban centers should see lows dip
into the 40s Monday and Tuesday nights.
&&
.AVIATION /12Z Wednesday THROUGH Sunday/...
Scattered showers and a few thunderstorms are spreading
northeast across the area this morning. This activity is likely
to wane this morning with some thinning of the clouds. Less
certain is the coverage of additional thunderstorms this
afternoon. A cold front remains will north of the area and is
expected to move southeast in the 18-23Z window. Thunderstorms
are possible along this axis but coverage remains in question.
Thunderstorms this afternoon also have the potential to be
strong but it remains difficult to pin down coverage and timing.
Most likely chances are at MFD/CAK/YNG and included a vicinity
mention of thunderstorms this morning. Conditions will be VFR
outside of precipitation but IFR is possible with heavy rain and
gusty winds. Later tonight a secondary push of cold air will
arrive and ceilings will trend towards MVFR from north to south.
Moist boundary layer conditions will remain tonight and if
breaks in the clouds develop could see fog formation. Have
introduced some MVFR and IFR conditions into the TAFs late
tonight but may need to trend more pessimistic.
Winds are generally 10 knots or less out of the south this
morning but will veer around to northwest with the passage of
the front this afternoon and eventually northeast tonight.
Outlook...Non-VFR will be possible tonight behind a cold front.
Non VFR possible again with thunderstorms on Friday/Friday
night. Non-VFR possible behind the cold front on Saturday.
&&
.MARINE...
A cold front will cross the lake today, flipping winds around from
the west-southwest at 6-12 knots this morning to the north-northeast
at similar speeds this afternoon. Winds turn more east-northeast
tonight through Thursday evening and will increase to 10-15 knots
during the day Thursday, which will build 2-3 footers for a period
of time, especially east of the islands. Winds will shift south at 6-
12 knots later Thursday night into Friday as a warm front lifts
across the lake. Winds will turn west-northwest Friday night into
Saturday with a cold front. There may be a brief period of 10-15
knot winds with the frontal passage, otherwise winds will remain
modest. The more onshore flow could produce a period of 1-3 footers
in the nearshore waters east of the islands into Saturday. Winds
turn west-southwest Saturday night into Sunday and increase to 12-16
knots during the day Sunday ahead of a secondary cold front. Winds
turn northerly at 13-18 knots Sunday night into Monday behind this
front. Winds turn more east-northeast Monday night into Tuesday and
subside a bit to 6-13 knots as high pressure builds in from the
north. The stronger northerly flow Sunday night into Monday will
likely build 2-4 footers in the nearshore waters. Given a pretty
chilly airmass (for the beginning of September) advecting in behind
this secondary front, a brief period of stronger winds and higher
waves, potentially necessitating a Small Craft Advisory, is not
ruled out Sunday night into Monday.
Thunderstorms remain possible over the lake into this morning ahead
of the approaching cold front. Any thunderstorms this afternoon or
evening appear more likely to focus just inland from the lake. A few
more thunderstorms are possible over the lake Friday into Friday
night as the next cold front moves through.
&&
.CLIMATE...
Temperatures will approach record values at some climate sites Today.
The following are record highs for Wednesday August 28.
Date Toledo Mansfield Cleveland Akron Youngstown Erie
08-28 96(1973) 92(1973) 98(1953) 94(1973) 96(1948) 93(2018)
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...None.
&&
$$
SYNOPSIS...KEC
NEAR TERM...KEC
SHORT TERM...Sullivan
LONG TERM...Sullivan
AVIATION...KEC
MARINE...Sullivan
CLIMATE...
Source:
CLE issues Area Forecast Discussion (AFD) at Aug 28, 7:21 AM EDT---------------
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