331 
FXUS61 KCLE 010759
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
359 AM EDT Sat Jun 1 2024

.SYNOPSIS...
High pressure departs east today, with weak low pressure moving
east across the region late tonight and Sunday. High pressure 
briefly returns Sunday night and Monday before a warm front
lifts through Monday evening. The area remains in the warm 
sector until a cold front crosses Wednesday night or Thursday.

&&

.NEAR TERM /THROUGH SUNDAY/...
After one last chillier start early this morning the atmosphere
will get the memo that it is now "meteorological summer" and
respond accordingly, with a warm and largely dry day on the
backside of departing high pressure. A shortwave and weak
surface low will be lifting out of the mid-Mississippi Valley
today which will cause high clouds to spread in and begin
thickening and lowering late this afternoon into this evening, 
however, rain chances don't begin ramping up until this evening 
and tonight. Highs will be near or better than 80 for most.

While the shortwave and surface low are not anything to write
home about from a meteorological perspective, they will bring 
enough forcing for ascent that when combined with a seasonably 
moist airmass much of the area can expect showers tonight into 
Sunday. POPs ramp up from the west starting this evening. Dry 
low-levels in place ahead of the rain make the onset time of 
rain a bit uncertain and slowed down the onset of POPs just a 
bit from the prior forecast. Regardless, by early Sunday showers
should have spread into most of our Ohio counties and will be 
spreading into Northwest Pennsylvania. A modest slowing trend 
continues with this system and our entire forecast area will be 
ahead of the shortwave trough axis and weak surface low early
Sunday, which is where forcing will generally be maximized in a
warm/moist advection regime. Given this, notably increased POPs
area-wide for Sunday morning. The shortwave trough axis should 
cross the OH/PA boarder early to mid-afternoon on Sunday with 
shower coverage decreasing behind that trough axis. Held on to 
"likely" shower wording in far Northeast OH and Northwest PA 
into early Sunday afternoon. Behind the shortwave trough axis
POPs do decrease quite a bit, though modest heating of a moist 
airmass combined with broad convergence in the vicinity of 
remnant surface low will likely support isolated to scattered 
shower re-development Sunday afternoon. Given this, increased 
POPs to keep at least a 20-30% type mention in everywhere until 
Sunday evening.

All in all Sunday will not be a true washout of a day but it 
looks showery area-wide out of the gate with fairly numerous 
showers not exiting our eastern counties until some point in the
afternoon. At least isolated pop-up activity remains possible 
in the afternoon behind the main batch of showers. Area-average 
rain amounts of 0.10-0.30" are anticipated with no concern for 
flooding. Thunder is appearing unlikely as overall instability 
will be quite limited. Lows tonight will generally remain in the
low to mid 60s with a few spots out east slipping into the 50s.
Highs on Sunday have been lowered a bit, ranging from the upper
60s to mid 70s. Light winds through the period. 

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/...
A ridge of high pressure builds in Sunday night, with cloud cover 
gradually dissipating from the west. Decreasing cloud cover, nearly 
calm conditions, and residual low-level moisture should result in 
some patch fog and low clouds late Sunday night into Monday morning, 
particularly low-lying areas along and east of I-71.

This surface ridge gradually departs eastward to the east coast 
Monday and Monday night. Southerly flow brings temps in the upper 
70s and low 80s on Monday and to the mid 80s by Tuesday, with 
moisture advection bringing dew points into the low 60s by Tuesday. 
Precipitation chances gradually increase from west to east, with 
isolated to scattered rain showers and thunderstorms to develop, 
mainly during the afternoon on Tuesday when there is likely to be 
some marginal uncapped instability (around 1000 J/kg or less). 
Currently have PoPs around 30-50% (higher out west such as Northwest 
Ohio, lower out east such as Northeast Ohio and Northwest 
Pennsylvania). However, some models have a weak shortwave moving 
northeast across the area on Tuesday, so it's possible PoPs could 
increase if this shortwave can provide forcing for a more focused 
area of convection. Either way, any rain that occurs is likely to be 
short-lived, with most of the day being precipitation-free.

&&

.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
An upper-level negatively-tilted low builds in from the northwest on 
Wednesday, with the trough axis likely extending southeastward 
across the upper Midwest and mid-Mississippi Valley at the start of 
the long term period. A surface low (likely occluded) will be 
located way back along the Quebec/Manitoba border in Canada, though 
a cold front will bisect the CONUS, extending across much of the 
Mississippi Valley to our west. We'll likely be within the warm 
sector and Wednesday will be our best best for modest instability as 
dew points are expected to rise into the upper 60s. This cold front 
and upper-trough axis should provide sufficient forcing for ascent 
and with modest instability forecast, have raise PoPs so that the 
entire forecast area has a period of 70-80% chance of precipitation. 
It won't necessarily be an all-day washout (in fact, most of the day 
will probably be rain-free) but synoptic-scale forcing is increasing 
confidence in a solid period of showers and thunderstorms some time 
between Wednesday afternoon through early Wednesday night. There is 
a low chance of severe weather with this activity, which is really 
dependent on the evolution of the upper-level trough. Some models 
have the best mid-level flow (and thus deep-layer shear) lagging 
behind, which would inhibit severe convection. Latest CSU-ML 
available to us (00Z/31) only shows a 5% chance of severe weather.

The upper-level low continues to build in, likely encompassing much 
of the Great Lakes region Thursday through Friday. This will likely 
bring cooler temperatures (near normal on Thursday, below normal on 
Friday), with scattered rain showers and afternoon isolated 
thunderstorms.

&&

.AVIATION /06Z Saturday THROUGH Wednesday/...
VFR through most of the day today. A weak area of low pressure
will begin spreading rain into TOL and FDY this evening,
approaching MFD near the end of the TAF period and arriving at
CLE after 6z Sunday as reflected in their 30 hour TAF. Dry low-
levels ahead of the rain will likely result in ceilings only 
slowly lowering. Expect some non-VFR by later tonight into early
Sunday due to lower ceilings and perhaps some periods of reduced
visibility in steadier rain, though only begin hinting at it at
TOL, FDY, and CLE near the end of their TAFs. 

Light and variable winds will shift out of the south-southeast
at 6 to 12 knots today. A lake breeze will likely flip winds
onshore for a few hours at ERI this afternoon. Currently think
the lake breeze won't quite reach CLE though it will be close.

Outlook...Some non-VFR likely spreads east late tonight into 
Sunday due to showers and lower ceilings before gradual
improvement through Sunday afternoon. Thunderstorms and
associated non-VFR possible at times Tuesday and Wednesday.

&&

.MARINE...
Conditions are expected to remain quiet with no marine headlines 
expected through at least the next few days. High pressure departs 
to the east coast today before a weak low moves to the vicinity of 
Lake Erie tonight and Sunday, dissipating and filling in as it does 
so. This low is replaced by a high pressure ridge that builds across 
the Great Lakes region Sunday night and Monday before it departs to 
the east coast. Southwest to southeast flow will be the prevailing 
winds Tuesday through Wednesday, with a low chance for near 20 knot 
winds on Wednesday.

&&

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

&&

$$

SYNOPSIS...Sullivan
NEAR TERM...Sullivan
SHORT TERM...Saunders
LONG TERM...Saunders 
AVIATION...Sullivan 
MARINE...Saunders