585
FXUS61 KCLE 130158
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
958 PM EDT Sun May 12 2024

.SYNOPSIS...
High pressure over the Ohio Valley this evening will exit
offshore of the Mid Atlantic coast tonight allowing a weak cold
front to drop to the vicinity of Lake Erie. This front will
return north as a warm front Monday as low pressure moves across
the Mississippi Valley. The low will then lift across the Great
Lakes Monday night and Tuesday extending a cold front into the
area.

&&

.NEAR TERM /THROUGH MONDAY NIGHT/...
No changes to the forecast at this time.

Previous Discussion...
Clouds that lingered much of the day over NE Ohio and NW PA have
cleared nicely allowing for a fair but cool afternoon as mid/upper
troughing lingers over the eastern Great Lakes. We only have to look
to the west and northwest to find our next weather makers though in
the form of a mid/upper shortwave trough in the Upper Midwest and a
southern stream closed low over the southern High Plains. Surface
high pressure currently over the Ohio Valley will quickly move
offshore of the Mid Atlantic coast tonight allowing the upstream
shortwave over the Upper Midwest to progress across the northern and
central Great Lakes. This will push a weak cold front southward into
Lake Erie late tonight before stalling in response to the southern
stream closed low and associated weak surface low approaching the
Mid Mississippi Valley. The cold front will be displaced well south
of the synoptic forcing tonight leading to very limited convergence
and moisture return, so expect any showers or rumbles of thunder to
be very isolated. However, with the boundary dropping into the area,
have slight chance to chance PoPs for lakeshore areas late tonight
and Monday morning, mainly in the 06-12Z timeframe.

The boundary will likely not make it any farther south than the
south shore of Lake Erie before it retreats back north as a warm
front Monday morning in response to the system over the Mid
Mississippi Valley. That closed low will become more of an open
shortwave trough as it lifts across Missouri and into Illinois
during the day Monday. Strong warm air advection ahead of this
system will lead to much warmer conditions and a sharp change to
well above normal temperatures Monday. NAM and RAP forecast
soundings suggest a weak cap in the 850-700 mb layer Monday
afternoon, so do not expect to see much in the warm sector, and low-
level moisture is also slow to return limiting MLCAPE values to a
couple hundred joules. However, the 3-KM NAM hints at some
convection near a lake breeze boundary in far NE Ohio and NW PA in
the afternoon, so it cannot be entirely ruled out. Most areas
will just be warm and dry Monday though. Precipitation chances
will expand east into the area Monday night as the weak surface
low associated with the shortwave rides up the boundary across
northern Illinois, finally supporting stronger moisture
advection and isentropic ascent into the southern Great Lakes.
This will support fairly widespread showers, and there will be
enough elevated instability for pockets of thunder, so have
likely PoPs in most areas Monday night.

Lows tonight will be milder ranging from the mid/upper 50s in NW and
north central Ohio to the mid 40s to low 50s in NE Ohio and NW PA.
Highs Monday will rise into the upper 70s/low 80s. Lows Monday night
will only fall into the upper 50s/low 60s.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Unsettled Tuesday in southwest flow aloft, a warm front draped
lengthwise along the Lake Erie axis, and the slow moving upper
trough axis just to the west of the CWA. Modest instability and
shear, but a drier layer sitting above 600mb in which the limited
instability could still tap into could make the convective scenario
slightly tricky. Will need to see how these details unfold a little
more going forward. System finally moves through late Tuesday night
into early Wednesday, transitioning to northeasterly flow into the
region with some lingering POPs in onshore low level moisture
advection. High pressure gradually builds into the Great Lakes
Wednesday night, and dries out the forecast as it does so.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
After brief ridging in the area Thursday, the next low pressure
system moves in for the end of the week and the first part of the
weekend. Significant differences exist in the evolution of this
system, so the details are not there right now but will carry POPs
in the extended that peak in the Friday/Friday night time frame.
Should get a little warmer from the short term into the long term
forecast period, and too early for now to try to dive into any sort
of storm threat for the long term.

&&

.AVIATION /00Z Monday THROUGH Friday/...
VFR conditions are expected through the TAF period. High
pressure is in control this evening into the first part of
tonight and will allow for light winds and clear conditions. A
cold front will pass to the north of the region and will allow
for some cirrus to enter late tonight. For NW PA and far NE OH,
some mid level clouds and some scattered rain showers could
enter late tonight into Monday and have a brief vicinity shower
mention. Return flow will allow for southwest winds to be
favored during the day on Monday and some wind gusts in the 20
to 25 kt range are expected. The next system will approach late
the period and have mid-level clouds returning with rain/storm
chances best expected after the TAF period.

Outlook...Non-VFR possible in showers and thunderstorms Monday
night through Wednesday.

&&

.MARINE...
Offshore winds 10-20kts through Monday weaken to 5-15kts Monday
night. Immediate nearshore waters less than a foot while the open
waters will reach 1-3ft during this time frame. A low pressure
system moves through Tuesday turning winds northeasterly 10-15kts,
increasing to 15-20kts Wednesday. Central and western basin wave
heights will be higher during this period as well where the higher
winds exist, pushing 2-4ft Wednesday. Onshore winds continue through
Thursday, but in lighter flows, waves subside to 1-3ft.

&&

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

&&

$$

SYNOPSIS...Garuckas
NEAR TERM...Garuckas/Sefcovic
SHORT TERM...26
LONG TERM...26
AVIATION...Sefcovic
MARINE...26