005 
FXUS61 KCLE 111947
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
347 PM EDT Thu Jul 11 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 FRIDAY NIGHT/...
For most of northern Ohio, it turned out to be a fairly nice
afternoon with partly cloudy skies and seasonably warm
temperatures with low humidity as a bonus. Portions of far NEOH
and NWPA are still stuck under lake effect cloud cover that has
been stubborn to scatter out. There is a weak area of high
pressure that is currently centered northwest Ohio this
afternoon and will continue to slowly move eastward tonight.
Winds have also been decreasing throughout the afternoon and
will continue to relax the area tonight. As we head into the
evening hours and especially after sunset, we will see the 
fair weather cumulus and lake effect clouds over NEOH and NWPA
quickly fade away and clear out. 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 /18Z Thursday THROUGH Tuesday/...
Most of northern Ohio has cleared out of the thicker lake effect
cloud cover with VFR conditions this afternoon. There is still a
pocket of MVFR ceilings due to lake effect clouds over far NEOH
and NWPA impacting YNG and ERI this afternoon. We expect these
areas to eventually break out of the MVFR ceilings and scattered
out the clouds later this afternoon into the early evening
hours. All areas will be VFR tonight into Friday morning. There
could be a little light fog around ERI after 06z tonight and
have this possibility mentioned in a TEMPO group for 5sm light
fog or BR through about sunrise. Some mid level cloudiness may
move into NWOH by Friday morning and there could be a couple
isolated rain showers around TOL and FDY but think the overall
chances are too low to mention in the TAF at this time for those
locations. 

Winds continue to slowly decrease this afternoon out of the
north and northwest 10 knots or less. Winds will be become
lighter tonight under 5 knots. Most areas will either have light
and variable winds or nearly calm conditions this evening into
the overnight. A light southeast winds may return 5 knots or
less over northwest and north central Ohio by Friday morning. A
lake breeze will shift the winds from the north-northeast by
midday or early afternoon for CLE and ERI about 8 knots or less.

Outlook...Isolated showers/thunderstorms with non-VFR possible
in NW Ohio Friday. 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
SHORT TERM...Kahn
LONG TERM...Kahn
AVIATION...Griffin
MARINE...Kahn