173
FXUS61 KCLE 220118
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
918 PM EDT Tue May 21 2024

.SYNOPSIS...
A strong low pressure system moving into northern Ontario
will push a cold front into the region Wednesday morning and
moving through later in the day Wednesday, stalling out along
the Ohio River Valley Wednesday night and Thursday. High
pressure Thursday. Another cold front stalls over northern Ohio
Thursday night into Friday.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
930 PM Update...
Made slight adjustments to temperatures as current temperatures
are a few degrees warmer than previously forecast. Ultimately
raised the overnight a degree or two across the area, but the
remainder of the forecast is unchanged.

630 PM Update...
The lake breeze has begun to weaken and any shower/thunderstorm
development along it has diminished. This should leave the area
dry until late tonight when the cold front approaches the area
from the west bringing with it the potential of some
showers/storms. There were minor adjustments to the wind
forecast to reflect the decaying lake breeze, but aside from
that there were no other changes needed.

Previous Discussion...
Plenty of surface based instability with heating today with low
level lapse rates over 7C/km, but there is clear evidence of mid
level drying occurring as seen on the mid level water vapor
satellite imagery. While a couple of isolated showers have formed
along the lakeshore east of Cleveland and near Erie, PA, the
thinking is that this drying will largely inhibit any large scale
convection today. However, a few more isolated cells during the
remainder of peaking heating cannot be completely ruled out along
the lake breeze boundary.

Meanwhile, a low pressure system moving into the Mississippi Valley
will continue an eastward track through the overnight hours.
Expecting a linear complex of storms to approach the western CWA
after 09Z tonight, but the thought is that moving into northwest
Ohio, these storms will likely be in a decaying phase. Cold front
enters the CWA after 12Z. Depending on the morning convective debris
moving eastward and how fast is dissolves out/moves out expecting
quick destabilization in the late morning hours with convective
initiation again after 15Z. Multiple forcing mechanisms possible here
with the cold front, old outflow boundaries, and possible
differential heating boundaries despite synoptic scale winds near
the lakeshore. Track of the low pressure system will turn northward
into the Thunder Bay region of northern Ontario and will be
occluding. Will get a noticeable decrease in the low level jet
strength Wednesday as a result with a lowering of the 0-6km shear.
Still have a wind threat with dry air above around 600mb that could
enhance gusts where the dynamics in the column may not be as strong.
The best threat for severe is roughly east of the I-71 corridor, and
still carry a slight risk from SPC for Wednesday. Some directional
shear could produce some rotating storms as well. Cold front will
ultimately be slow to exit the southeast zones into Wednesday night
with the front well out ahead of the aforementioned occluding
low.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY/...
The overall 500 mb mid level steering flow aloft will be west-
southwesterly towards the end of the week. A slow moving and weak
frontal boundary will be near central Ohio on Thursday. Afternoon
heating will allow for scattered showers and thunderstorms to once
again develop along and near this weak frontal boundary. The higher
POPs will be closer to central Ohio and lesser values near the
lakeshore areas. Thursday`s high temperatures will be a little
cooler than previous days but still in the middle 70s to lower 80s.

A shortwave trough will move across the Upper Midwest into the
western Great Lakes region on Friday. This shortwave trough will
help the stalled frontal boundary over central or southern Ohio lift
back as a warm front on Friday. Scattered showers and thunderstorms
will develop again with the warm front lifting through Friday
afternoon and evening. High temps will be warmer in the lower to
middle 80s on Friday.

A weak area of low pressure will track eastward across the Upper
Great Lakes region late Friday night into Saturday. A trailing cold
front will advance across the Great Lakes and Ohio Valley region
late Friday night. Showers and thunderstorms will be likely ahead
and along this frontal boundary late Friday night. It appears that
this system will be coming through during the weakest thermodynamics
and organized convection is not anticipated at this time.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
A cold front will be pushing through during the first half of the
day on Saturday. Showers and isolated thunderstorms will be possible
early in the day before drier air moves in from the west. High
pressure will build in over the area late Saturday into Saturday
night. Temperatures will be cooler this weekend with highs in the
70s and overnight lows in the 50s. Another shortwave trough will
track across the Ohio Valley late Sunday into early Monday with
another round of showers and storms. Temperatures will remain
slightly above average through the weekend.

&&

.AVIATION /00Z Wednesday THROUGH Sunday/...
Mostly clear skies this evening will gradually become mostly
cloudy tonight as a cold front approaches from the west.
Conditions should remain VFR through the period with the
exception of any showers and thunderstorms that develop ahead
and along of the aforementioned cold front. An initial round of
showers and isolated thunder is possible early Wednesday
morning, especially for western terminals which may briefly
reduce conditions to MVFR, but those conditions should remain
scattered. The second round of precipitation and the better
chance of thunderstorms will be along and east of I71 between
18-22Z Wednesday. Primary threat with the strongest storms will
be gusty winds, but cannot rule out some hail mixing in. Within
these showers, conditions may drop to MVFR again, but with the
scattered nature of the convection, opted to handle it in TEMPOs
for the terminals in the outlined area. Rain should end near the
end of the period and allow dry conditions to return.

South-southwest winds will slowly increase over the next couple
hours as the cold front approaches to be sustained at 10-15
knots, gusting up to 25 knots. Behind the boundary on Wednesday
late afternoon/evening, winds will shift to gain a more westerly
component and weaken to 5-10 knots.

Outlook...Scattered to numerous thunderstorms are expected
Wednesday into Wednesday night and may bring a brief period of
non-VFR conditions. Scattered showers and storms on Friday and
Saturday could also bring brief non-VFR conditions.

&&

.MARINE...
A lake breeze has developed again near the lakeshore this afternoon.
This weak lake breeze will fizzle out closer to sunset this evening.
Winds should shift from the southeast under 10 knots this evening. A
southwest flow of 10 to 15 knots will develop late tonight in
response to an approaching cold front by Wednesday morning. Winds
will diminish to 5 to 10 knots behind the front late Wednesday and
briefly become westerly Wednesday night. Winds will shift from the
south or southwest around 10 knots Thursday through early Friday.
East to southeast winds 10 to 15 knots are expected Friday night
through Saturday. No marine headlines for the lake are anticipated
at this time through the weekend.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Air Quality Alert until midnight EDT tonight for OHZ010>014-
     020>022-089.
PA...None.
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...26
NEAR TERM...Campbell/26
SHORT TERM...Griffin
LONG TERM...Griffin
AVIATION...Campbell
MARINE...Griffin