954
FXUS61 KCLE 120607
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
207 AM EDT Fri Jul 12 2024

.SYNOPSIS...
High pressure will over the southern Great Lakes region and the
Upper Ohio Valley tonight. A weak trough will track across the
Ohio Valley Friday with not much impactful weather associated
with it. High pressure will return Saturday and Saturday night.
A warm front will lift across the region from the southwest on
Sunday.

&&

.NEAR TERM /THROUGH TONIGHT/...
The northeast extent of rain in Indiana and western Ohio has
fallen apart immensely as it reached the forecast area this
evening, where dew points are barely into the mid 60s. This
first round of returns into the area did bump these dew points
up slightly, and will help the next round persist a touch more
later tonight. Have slowed down PoPs a bit over the next several
hours, but have some 20-30 PoPs near daybreak in the I-75
corridor.

Previous Discussion...
A system with lingering cloud cover continues to slowly depart
to the east. A component of a lake breeze has actually helped
clear some skies in far NE OH and NW PA from the broader low
overcast across the NE United States. This system will continue
to depart tonight. Meanwhile, across Indiana, an area of deep
moist convergence with surface dew points in the lower 70s and
the upper trough axis overhead has allowed for some showers and
storms to form. As these storms have moved northeast, they have
struggled to maintain as dew points in the forecast area are in
the lower 60s at best and the showers have not fended off this
more drastically dry air mass. Suspect the moisture in the local
area will improve with time tonight into Friday as the upper
trough shifts east and have PoPs entering late tonight into
Friday. However, do not have PoPs imminently into NW OH, as this
first wave is struggling.

Most of the Previous Discussion...
With light winds and mostly clear skies tonight, we will see
overnight low temperatures rather comfortable due to the
slightly drier airmass. Low temps will drop into the lower and
middle 60s for most of the area with a few upper 50s possible in
those favored cooler spots.

The next weather system to talk about is a very weak and
somewhat moisture starved trough that is currently over
Illinois and western Indiana this afternoon. This rather weak
system will move towards western Ohio by early Friday morning
with an increase in high and mid level clouds and the chance for
a few scattered showers and isolated thunderstorms. These
spotty rain chances could move into NWOH by daybreak Friday
morning. Overall we kept POPs at 20 to 35 percent for mainly the
western half of the CWA or basically west of I-71 for Friday
morning into the afternoon. It appears that any showers or
isolated convection will be mostly diurnally driven on Friday
and should showers will fade away by early Friday evening.
Temperatures will be warmer Friday afternoon with highs in the
middle to upper 80s. With relatively weak low level winds, there
will likely be a lake breeze that develops midday through the
afternoon on Friday and push inland from the lakeshore. Quiet
weather is expected for Friday night with temps in the middle to
upper 60s for overnight lows.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Late Sunday marks what could be the beginning of an active stretch
of convective weather across the Great Lakes region.

Current water vapor imagery depicts a well-defined Elevated Mixed
Layer across the Southwest CONUS, with the morning NUCAPS pass
indicating mid-level lapse rates as high as 10C/km. A developing
upper-level trough leeward of the Canadian Rockies is expected to
develop on Sunday and Sunday night, advecting some of these rich,
mid-level lapse rates eastward across portions of the Upper Midwest
and Great Lakes into early next week. At the surface, a warm front
is expected to lift northeastward through the area on Sunday. Some
scattered showers and storms associated with isentropic lift along
the front are possible beginning late Sunday morning into the early
afternoon, though not anticipating any strong to severe storms.

Behind the front late Sunday afternoon and evening, steep mid-level
lapse rates and enhanced flow begin to enter the region from the
west. Warm mid-levels may result in a capping inversion initially,
but do anticipate convection to fire along the instability gradient
at some point Sunday evening/overnight with support from ensemble
clusters, suggesting the arrival of a 30 to 35 knot 500 mb
shortwave. The question remains as to where convection is able to
fire, given uncertainty in the location of the instability gradient
and capping strength. Any storms that are able to develop Sunday
evening and overnight would carry a strong to severe weather
potential.

For Saturday, a few isolated showers and thunderstorms are possible
in the afternoon and early evening hours, aided by a developing lake
breeze and residual low-level moisture from Friday night. However,
forecast soundings do indicate quite a bit of dry mid-level air
which could be a limiting factor for updraft strength.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The potential for active weather will continue through much of the
long term period as steep mid-level lapse rates contribute to strong
instability across the region in addition to persistent northwest
flow aloft. Large uncertainty remains in the forecast with regards
to location and timing of thunderstorm initiation, particularly on
Monday. There is slightly higher confidence in thunderstorms on
Tuesday and Tuesday night as a cold front is expected to sweep
southeast across the area. Depending on how fast the cold front
progresses through the region, there could be additional
thunderstorm development on Wednesday as well. Any thunderstorms
that develop through this period (Monday to Wednesday) will have the
potential to bring severe weather across the region, given the
strong to perhaps extreme instability in addition to persistent mid
and upper-level west to northwest flow of 35 to 40 knots.

Because of uncertainty on storm timing and location, there also
remains uncertainty in the temperature forecast. However, if storms
are able to hold off during the daytime hours, we`ll need to monitor
potential heat impacts as well, with Heat Indices reaching into the
upper 90s to near 100 on Monday and Tuesday.

Quiet and more seasonable weather should return by Thursday as
confidence grows that the cold front will be south of the area.

&&

.AVIATION /06Z Friday THROUGH Tuesday/...
Will be monitoring for some fog this morning, mainly in typical
locations including YNG. Based on some ground fog already being
reported at YNG with clear/calm conditions continuing did hit
the fog a bit harder with this TAF cycle there. Otherwise am
expecting limited impact at other TAF sites, though maintain a
brief MVFR TEMPO at ERI near and just before sunrise. Locations
that see reduced visibility/low ceilings in fog should see quick
improvement 12-13z as the sun comes up.

The main aviation concern for the rest of the TAF period will be
potential for a few showers (and isolated thunder this
afternoon) as a weak disturbance currently over Indiana works
east across Ohio today. Showers are beginning to expand across
northern Indiana and will drift into the TOL and FDY areas this
morning. Activity will slowly drift east-northeast through the
afternoon, and may expand a bit this afternoon. For now
maintained a broad VCSH mention, though may be able to time more
specific mention within the next several hours to TOL and FDY.
Also added VCSH to MFD, as much of Northwest and North Central
OH may see isolated to scattered showers later this morning into
this afternoon. Thunder potential is more isolated so didn`t
include anywhere for now, though future cycles may be able to
add some brief/targeted thunder to a site or two. Some mid
level ceilings will spread east across the other terminals
through the day. Winds will generally be light and variable
through the period, though a period of 5-10 knot onshore flow is
likely at CLE and ERI due to a lake breeze this afternoon.

Outlook...Periodic rounds of showers and thunderstorms with
non-VFR may be possible this Sunday through Tuesday.

&&

.MARINE...
Marine conditions will continue to improve tonight as high pressure
builds in across the Great Lakes. Relatively quiet marine conditions
are then expected to persist into early next week as offshore flow,
10 to 15 knots, will be favored beginning Sunday. Strong to severe
thunderstorms chances may begin to increase late Sunday into early
next week and will continued to be monitored.

&&

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

&&

$$

SYNOPSIS...Griffin
NEAR TERM...Griffin/Sefcovic
SHORT TERM...Kahn
LONG TERM...Kahn
AVIATION...Sullivan
MARINE...Kahn