-- Discussion containing changed information from previous version are highlighted. --
218
FXUS61 KCLE 060605
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
205 AM EDT Thu Jun 6 2024

...06z TAF Aviation Forecast Update...

.SYNOPSIS...
A cold front will cross the area this evening into tonight with
a secondary cold front following on Thursday. A trough will
persist over the Great Lakes late this week through the weekend.

&&

.NEAR TERM /THROUGH TODAY/...
Showers and thunderstorms across the scope this evening will
need to be monitored over the next couple of hours. The most
robust area of storms has been over Lake Erie, moving into Lake
and Ashtabula Counties and will continue east into NW PA. Winds
with this cluster have been in the 35-45 mph range and Special
Marine Warnings are out for Lake Erie. Another stronger area of
storms has been in central Ohio, moving through Marion and
Morrow Counties. There has not been too much of a bite with
these storms with wind or hail, but heavy rainfall has been
occurring in this region and a flood advisory is out for a few
counties. Rain will continue east across the area, but intensity
will wane.

Previous Discussion...
Clearing is still occurring across the area and have seen rapid
destabilization with SBCAPE values approaching 2000-2500 J/kg
near the I-75 corridor and MLCAPE values approaching 1000-1500
J/kg in the western half of the CWA. A line of storms, currently
over the I-75 corridor, will move farther east into the area
over the next several hours before exiting to the east later
this evening. CAMs have generally underestimated the amount of
destabilization this afternoon and most high res guidance from
earlier in the day has held off on stronger convection until the
cold front (currently over eastern IL) approached from the west
late this afternoon into this evening. Based on how things are
looking right now, this line should be the main show with benign
showers/thunderstorms with the front later this evening since
the atmosphere will be worked over.

Given the amount of moisture (PW values are over 1.5 inches
which is well above normal for this time of year),
buoyancy/CAPE, and effective bulk shear values to 20 to 25
knots, there may be isolated damaging wind gusts/downbursts. So
far there have only been a couple of instances of wind gusts
over 40 knots (still below severe limits), but the severe
weather risk may increase at least a little bit as clearing and
destabilization continue late this afternoon. Heavy rain will
be a big concern since PW values are so high, CAPE profiles are
tall and skinny, and warm cloud layers are deep. Storm motion
may be a hair fast, but torrential rainfall rates and potential
for backbuilding could result in flooding primarily in low-
lying and urban areas. Can`t totally rule out isolated large
hail since instability is a bit higher than previously
anticipated, however the tornado threat remains low since shear
values are marginal. The severe weather risk will diminish
throughout the evening as diurnal instability wanes. Long story
short, isolated damaging wind gusts and heavy rain/flooding are
the main threats today.

Scattered showers will likely persist behind the line of
convection and ahead of the front tonight. The front should be
to the east of the area by mid-morning Thursday, but the next
trough/reinforcing surface cold front will pivot across the area
by Thursday afternoon/evening. Moisture will be somewhat
limited, but there will still be slight chance to chances of
scattered showers and isolated thunderstorms. Lake-enhanced
rain chances increase further across NE OH and NW PA Thursday
night as cold air advection settles in behind the reinforcing
cold front and 850mb temperatures fall to 5 to 10C.

Tonight`s lows will be in the low to mid 60s with highs reaching
the mid to upper 70s Thursday. Cyclonic flow aloft in addition
to cold air advection will result in cooler minimum temperatures
in the low to mid 50s.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
Aloft, cyclonic W`erly to NW`erly flow and embedded shortwave
disturbances affect our region through the short-term period as a
mid/upper-level low wobbles E`ward and then NE`ward from near
Georgian Bay to near central QC. At the surface, troughing lingers
over/near our CWA and trough axes will accompany the aforementioned
shortwave disturbances. This pattern will maintain a chilly air mass
for early June across northern OH and NW PA. Periods of isolated to
scattered rain showers are expected due to moist isentropic ascent
preceding shortwave trough axes, low-level convergence/moist ascent
along attendant surface trough axes, and the presence of potential
instability in the surface to roughly 850 mb layer. Daytime heating
of the relatively-moist boundary layer coinciding with considerably
colder air farther aloft should yield weak, yet sufficient mixed
layer CAPE for isolated thunderstorm development each afternoon
through early evening. The greatest potential and coverage of
convection are expected each afternoon through early evening because
a typical diurnal cycle in boundary layer temperatures and
instability is expected. In addition, a sufficiently-cold/moist
low/mid-level atmospheric column and the seeder-feeder process
should support periods of lake-enhanced rain over/generally east or
southeast of ~18C Lake Erie, in/near our snowbelt counties, during
the late evening through morning hours of Friday into Saturday and
Saturday into Sunday. Late afternoon highs should reach the mid 60`s
to lower 70`s on Friday and the upper 60`s to mid 70`s on Saturday.
Overnight lows should reach mainly the upper 40`s to mid 50`s around
daybreak Saturday and mainly the 50`s around daybreak Sunday.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Cyclonic W`erly to NW`erly flow aloft and embedded shortwave
disturbances should continue to affect our region on Sunday through
Monday. At the surface, troughing persists over/near the eastern
Great Lakes and Upper OH Valley, and multiple trough axes will
accompany the shortwave disturbances. This pattern at the surface
and aloft will allow an unusually-cool air mass to remain entrenched
across our CWA. Periods of isolated to scattered showers and
thunderstorms are expected for the same reasons noted in the short-
term discussion. The greatest potential and coverage of convection
are expected each afternoon through early evening due to a continued
typical diurnal cycle in boundary layer temperatures and
instability, and self-destructive sunshine. Periods of lake-enhanced
rain remain possible over and generally east or southeast of Lake
Erie Sunday morning and again Sunday evening into Monday morning for
the same reasons noted in the short-term discussion. Daily afternoon
highs are forecast to reach the mid 60`s to mid 70`s. Overnight lows
should reach mainly the 50`s around daybreak Monday morning.

Odds favor fair weather on Monday night through Tuesday night as the
cyclonic flow aloft and associated surface troughing exit generally
E`ward, a ridge at the surface and aloft builds generally E`ward
over/near our CWA, and stabilizing subsidence accompanies the ridge.
Low-level WAA will eventually impact northern OH and NW PA as our
CWA becomes located generally west of the low-level ridge axis.
Overnight lows should reach mainly the upper 40`s to upper 50`s
around daybreak Tuesday and be followed by highs in the lower 70`s
to lower 80`s late Tuesday afternoon. Overnight lows should then
reach mainly the 50`s to lower 60`s around daybreak Wednesday. At
the surface and aloft, the ridge should begin to exit E`ward on
Wednesday as a trough begins to enter from the Upper Midwest and
vicinity. A few showers and thunderstorms are possible on Wednesday
as low-level isentropic ascent preceding the trough axis aloft
coincides with increasing low-level moisture from the Gulf of Mexico
and releases at least weak instability, including elevated
instability. Late afternoon highs should reach mainly the mid 70`s
to lower 80`s.

&&

.AVIATION /06Z Thursday THROUGH Monday/...
-- Changed Discussion --
The main message for this aviation weather and TAF update will
be some patchy fog will be possible as well as some low stratus
redeveloping with some of the fog. Conditions will vary
across the area through sunrise this morning with clearing skies
pushing in from west to east through the early morning. But
where areas saw rainfall this evening and overnight, those
clearing skies may help with the development of some fog and
broken IFR/LIFR ceilings due.

For NWOH TAF sites, generally just VFR is expected for the next
24 hours through the rest of this overnight through Thursday
evening. For NEOH and NWPA TAF sites, have some partial clearing
but again there may be the potential for some fog and low
stratus redevelopment off the surface. Confidence level is not
overly great with how much fog could form and how much will be
impacting individual airports through sunrise this morning. In
general, have TEMPO group highlighting 08z to 12z this morning
for 3sm to 5sm light fog and broken ceilings around 700 feet at
a couple locations like MFD, CAK, and YNG. As for ERI, there may
be a slightly better chance for some lake enhanced fog with 2sm
possible during the 08z to 12z timeframe. Any fog and low
stratus should burn off fairly quickly by 13z or so this morning
with the strong sun angle and a cold front that will be
tracking through the area later this morning.

Winds will be light and variable through sunrise or from the
south around 4 to 7 knots. Gusty winds will return for all
locations after 15z or 16z today behind a cold front from the
west direction with speeds of 12 to 16 knots and gusts up to 20
to 25 knots midday through the afternoon. Gusts and winds will
relax after sunset or 00z this evening but remain from a
westerly direction 8 knots or less.


Outlook...Non-VFR will be possible with the chance for
scattered rain showers Thursday night through this weekend. An
isolated general thunderstorm or two could also be possible
Friday through the weekend.
-- End Changed Discussion --

&&

.MARINE...
A cold front is still poised to sweep E`ward across Lake Erie this
evening through early Thursday morning and clear Lake Erie by
daybreak. Otherwise, a trough lingers over the lake. The cold
front`s passage will cause SSE`erly to SW`erly winds around 5 to 15
knots to veer toward W`erly. Waves remain 3 feet or less through
Thursday. Occasional 4 footers are possible east of The Islands on
Thursday, especially in open waters.

Winds around 10 to 20 knots are expected to vary between SW`erly and
NW`erly on Thursday night through Sunday as a trough continues to
linger over Lake Erie. Waves are expected to be as large as 3 to 6
feet east of The Islands and 3 feet or less elsewhere. One or
multiple Small Craft Advisories and Beach Hazards Statements for the
adjacent shore will likely be needed. W`erly to N`erly winds around
5 to 15 knots are expected Sunday night into Monday as the trough
weakens over the eastern Great Lakes region and a ridge attempts to
begin to build from the north-central United States. Waves are
expected to subside to 3 feet or less.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...Maines
NEAR TERM...Maines/Sefcovic
SHORT TERM...Jaszka
LONG TERM...Jaszka
AVIATION...Griffin
MARINE...Jaszka