517
FXUS61 KCLE 140013
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
813 PM EDT Thu Jun 13 2024

.SYNOPSIS...
A ridge exits generally eastward before a cold front sweeps
southeastward through our region during the predawn through
mid-morning hours of Friday. Behind the front, a ridge builds
from the Upper Midwest through Saturday before it begins to
exit slowly toward New England on Sunday.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
Showers and thunderstorms that developed across SW Lower
Michigan this afternoon have weakened in intensity as they moved
into the more stable air across NW Ohio. Light rain with a few
thunderstorms has filled in across the greater Toledo area
where a narrow ribbon of moisture advection is focused to the
south of the shortwave crossing the Great Lakes Region. We do
expect the coverage of showers to decrease as they gradually
settle south into the drier air across Ohio. Some models try to
develop isolated to widely scattered showers or thunderstorms
east of Lake Erie along the pre-frontal trough with the better
location focused towards Ashtabula/Erie Counties through 10 PM.
Otherwise, the chance of showers and thunderstorms does remain
in the forecast for late tonight as the cold front settles
south.

Previous discussion...
Aloft, W`erly flow and embedded shortwave disturbances affect
our region through Friday afternoon. Flow veers to NW`erly
Friday evening with the passage of a stronger shortwave
disturbance and as a subsequent ridge builds from the central
U.S. and vicinity. At the surface, a ridge exits generally
E`ward before a cold front sweeps generally SE`ward through our
region during the predawn through mid-morning hours of Friday.
Behind the front, a ridge builds from the Upper Midwest and
vicinity through daybreak Saturday. Tonight`s lows are expected
to reach the 60`s around daybreak Friday. On Friday, low-level
CAA behind the front will contribute to cooler late afternoon
highs. Readings are expected to reach the lower to mid 70`s in
NW PA and mainly the mid 70`s to mid 80`s in northern OH. The
warmest highs are expected in our I-75 corridor counties. Friday
night`s lows are forecast to reach mainly the 50`s around
daybreak as continued low-level cold/dry air advection and
considerable clearing accompanying the building ridge contribute
to efficient radiational cooling.

Primarily fair weather is expected during the near-term period
due to stabilizing subsidence accompanying the pre-front and
post-front ridging. However, upstream showers/thunderstorms
initiating along a pre-front surface trough may overspread our
I-75 corridor counties, Lake Erie, and vicinity this evening,
especially after sunset. Additional isolated showers and
thunderstorms are expected along the surface cold front and
along the upper-reaches of the front. The frontal convection
should exit gradually E`ward or SE`ward between roughly daybreak
and early evening on Friday. However, a few showers/thunderstorms
associated with low-level convergence/moist ascent along the
prominent shortwave trough`s attendant surface trough axis may
enter NW OH from the northwest Friday evening before dissipating
around sunset as the boundary layer stabilizes via nocturnal
cooling. Showers/thunderstorms are expected to be organized
given the expectation of weak to moderate instability, including
elevated CAPE, amidst moderate to strong deep layer bulk shear.
Weak mid-level lapse rates and development/growth of DCIN
associated with nocturnal cooling-related boundary layer
stabilization should contribute to very limited potential for
severe thunderstorms through Friday morning. However, during
Friday afternoon through early evening, a few thunderstorms may
become severe with damaging convective wind gusts, especially
roughly along/south of the U.S. 30 corridor, where greater low-
level moisture should yield greater MUCAPE and sufficient
diurnal convective mixing of the boundary layer should yield
moderate to strong DCAPE and weak or no DCIN amidst steep low-level
lapse rates.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
A dominant upper level ridge will begin to push east across the
region on Saturday. This will produce a large area of subsidence
over the region, allowing for dry conditions to persist. The bigger
story over the weekend and into next week will be the rising
temperatures. Behind the departing cold front from Friday night,
temperatures on Saturday will only climb into the mid 70s along and
east of I71 and possible touch 80 west of I71. With dewpoints
lingering in the mid 40s to low 50s, the weather will feel pleasant.
Saturday night will cool into the mid to upper 50s. On Sunday, as
WAA increasing, temperatures will climb into the mid 80s to low 90s,
but again with dewpoints in the low 50s the apparent temperature
will feel close to the actual temperature. Overnight lows will be
warmer Sunday night, only falling into the mid to upper 60s,
possibly not dropping below 70 in some locations.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
On Monday, a shortwave trough is expected to move along the northern
edge of the ridge becoming established over the eastern US. With
south-southwesterly flow expected to establish both WAA and
increased moisture advection across the area, cannot rule out a few
afternoon thunderstorms developing when instability is at its
greatest, especially across the northern counties. Confidence in
this is low, especially if the vort max shifts further north and
limits upper level support. For the remainder of the period, there
is a non-zero chance of isolated afternoon thunderstorms, but given
the non-favorable synoptic pattern, not expecting anything
widespread.

The biggest story through the long term period will be the rising
temperatures to well above normal for this time of year. Monday
temperatures will start in the low to mid 90s everywhere and will
persist through Thursday. With dewpoints expected to linger in the
60s, possibly reaching into the 70s at times, the conditions outside
will be quite muggy and the apparent temperature values will
approach 100 degrees, especially across western counties. Important
to note that the forecast reflects a bit warmer of a trend than some
long range models to try and account for the very dry antecedent
conditions at the surface and the impacts that will have on overall
temperatures. As a result of these conditions, the NWS HeatRisk tool
has ranked the impact from these temperatures as major to extreme,
noting that people will be affected without effective cooling and/or
adequate hydration and that there will be little relief overnight as
temperatures linger in the 70s. The greatest impacts will be felt in
some health systems, heat-sensitive industries,and infrastructure.
Please remain updated with the latest forecast and prepare for the
hot conditions in advance.

&&

.AVIATION /00Z Friday THROUGH Tuesday/...
A mid level cloud deck will expand across the area this evening
with light rain and isolated thunderstorms ongoing near TOL at
00Z. This rain is expected to decrease in coverage as it
encounters drier and more stable air to the south and east.
There is a low 20-30 percent chance of a few showers and
thunderstorms developing east of Lake Erie this evening through
approximately 02Z. Otherwise the next round of precipitation is
expected to occur after 08Z when a cold front settles south
across the area. Eastern terminals could see a few showers and
can not rule out a thunderstorm through 14Z but confidence in
thunderstorms during the pre-dawn hours is not high enough to
include in the TAFs at this time. Better chances of
thunderstormswill be focused from CAK south during the midday
period (15-19Z) where some instability will develop before the
front pushes south on Friday. Ceilings will primarily be VFR but
MVFR is possible at mainly the inland terminals between 11-15Z.
IFR visibilites will be possible in thunderstorms on Friday.

Wind gusts will drop off shortly after 00Z this evening.
Southwest winds will veer to northwesterly and eventually
north/northeast behind the frontal passage overnight into Friday
morning.

Outlook...VFR through this Tuesday.

&&

.MARINE...
Low pressure currently centered over Lake Superior will drag a cold
front east across Lake Erie tonight. Showers and thunderstorms are
possible along and ahead of the boundary. In addition, winds ahead
of the cold front will remain from the southwest at 10-15 knots
before shifting to north-northwest flow by Friday morning and
weakening to 5-10 knots. This shift to northerly flow will result in
waves up to 2 feet along the coast of Lake Erie. As a dominant upper
level ridge and associated high pressure shift over the region,
winds will shift out of the east-northeast at 5-10 knots for
Saturday and Sunday. Offshore flow of 5-10 knots becomes established
Sunday night and looks to persist for much of next week as the
aforementioned ridge remains in place.

&&

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

&&

$$

SYNOPSIS...Jaszka
NEAR TERM...KEC/Jaszka
SHORT TERM...Campbell
LONG TERM...Campbell
AVIATION...KEC
MARINE...Campbell