-- Discussion containing changed information from previous version are highlighted. --
131
FXUS61 KCLE 180536
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
136 AM EDT Tue Jun 18 2024

.SYNOPSIS...
An upper level ridge will persist over the region through this
week, resulting in widespread near-record temperatures across
the area. The next system won`t arrive until the end of the
weekend.

&&

.NEAR TERM /THROUGH TODAY/...
930 PM Update...
Slight adjustments were made to the temperatures to reflect
current observations, but not big changes were needed with this
update.

630 PM Update...
The biggest update/change with this forecast was lowering
temperatures in areas that have seen precipitation between 15-20
degrees in the hourly forecast. Across NW OH, temperatures
continue to linger in the 90s, but some areas out east have
fallen into the 70s do to evaporative cooling. This should not
impact overnight lows much with them still expected to drop near
70. Opted to introduce patchy fog across the southeastern tier
of counties primarily due to these cooling temperatures but
dewpoints remaining high. Cannot rule out patchy fog occurring
elsewhere in areas that it rained this evening. A similar
situation may occur tomorrow with afternoon thunderstorms
locally lowering temperatures, but will need to continue to
monitor that potential.

Previous Discussion...
Scattered showers and thunderstorms are developing across the
forecast area this afternoon, as convective temperatures are
being reached in the mid 90s and surface dew points start
broaching the 70 degree mark across northern Ohio. However, with
no real forcing other than the diurnal forcing, coverage is
just scattered across the region. However, the environment for
these storms is generally supportive for strong to severe
convection with SBCAPE values reaching over 3500 J/kg, DCAPE
values exceeding 1000 J/kg, and low level lapse rates in excess
of 8 C/km, which will support robust, quickly growing updrafts
that will support severe sized hail and tall enough cores that
could descend as downbursts with winds over 60 MPH. Several
Severe Thunderstorm Warnings and Special Weather Statements are
ongoing and the environment appears favorable for strong to
severe storms through early evening. Convection will move east
of the area later this evening and subside with a more stable
environment with the loss of diurnal heating. Residual cloud
cover across the region from this afternoon`s storms could
remain for some portion of tonight and help keep temperatures
slightly elevated with lows likely not escaping the 70s for most
of the forecast area.

Tuesday appears to be a rinse and repeat of today. An abnormally
warm summer air mass will allow for temperatures to exceed 90
degrees and dew point values will once again approach the 70
degree mark. This will allow for heat index values to exceed 100
degrees and the Heat Advisory will remain valid. Temperatures
should hit convective temperatures again with the diurnal cycle
and scattered showers and storms will be present again. Storms
could once again have a bite with an generally unstable
environment to support some strong to severe wind and hail. Any
convection will also taper off temperatures and heat index
values from hitting the Heat Advisory values. Residual clouds
and abnormally warm air mass will have another dry, but warm
Tuesday night with lows likely staying above 70 degrees.

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
Strong upper high will maintain itself over the eastern CONUS
through the short term period with southerly flow, deep moisture
advection, and steamy temperatures continuing through mid to
late week. As stated in the previous discussion from last night,
the main challenge is how much convection occurs during this
time and how much that will impact the temperatures and dew
points. Regardless, temperatures will likely climb well into the
90s each day with spots in NW OH most likely reaching the upper
90s to around 100 degrees. There won`t be a ton of respite
overnight; overnight lows will be in the 70s with the warmest
temps expected in urban areas and dew points in the upper 60s
to lower 70s. In locations that don`t receive rainfall, heat
indices will likely climb into the upper 90s to lower 100s and
the Heat Advisory remains in place through the entirety of the
long term period.

As far as precip chances go, maintained slight chance PoPs
during peak diurnal heating/instability; shower and thunderstorm
placement will rely on the exact placement of the upper ridging
over the area in addition to any boundaries from daily lake
breezes since there won`t be much lift otherwise. Similar to
today, there will be quite a bit of buoyancy and moisture in the
atmosphere so any storms that develop could produce gusty
downbursts and locally torrential rainfall.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
By Friday, the upper ridge will largely weaken and flatten out,
but deep southerly flow and warm air advection will persist
through Saturday so still expect highs in the 90s with heat
indices in the upper 90s to lower 100s on Friday. Dew points may
begin to decline slightly Saturday, so heat indices will likely
remain in the 90s. As with previous days, there may be diurnal
convection so there are slight chance PoPs during each
afternoon.

Still some uncertainty in the time of arrival of the next
system, but a cold front will likely slowly advance east towards
the area late in the week and into the weekend with a cold
front likely sweeping across the area at some point Sunday or
Sunday night. This will deliver the next widespread chance of
showers and thunderstorms and finally some relief from the
heat to the CWA. By Sunday, highs will be back into the upper
80s to lower 90s with much cooler highs in the 80s (even 70s in
NW PA!) likely by Monday.

&&

.AVIATION /06Z Tuesday THROUGH Saturday/...
-- Changed Discussion --
Went with a lesser used route of PROB30 groups in the TAFs for
expected isolated to scattered thunderstorm activity that will
peak with heating Tuesday. Some of this is a persistence
forecast, based on the amount of storms that occurred Monday,
but still, terminals themselves not guaranteed to get affected
directly. This may be switched to TEMPOs or VCTS/CB in upcoming
issuances, but feel the this setup is ideal for the PROB30
usage. Otherwise, mainly southerly wind components 5-10kts away
from storms and cumulus clouds developing with heating after
15Z.

Outlook...Primarily VFR expected through Friday. Isolated
thunderstorms are possible Wednesday afternoon.
-- End Changed Discussion --


&&

.MARINE...
Outside of the potential for isolated showers and thunderstorms
(best chance this afternoon/evening and Tuesday), quiet marine
conditions with offshore winds under 10 knots and brief periods
of light onshore flow with daily lake breezes are expected
through Saturday. Do not expect any marine headlines this week.

&&

.CLIMATE...
A prolonged stretch of hot weather is expected this week.
Temperatures are forecast to approach or exceed record highs on
several days. The records for Monday, June 17 to Friday, June
21 are listed below for our official climate sites.


Date   Toledo     Mansfield   Cleveland   Akron     Youngstown   Erie
06-17  97(1994)    94(1936)   94(2018)    94(2018)   95(1994)    90(2018)
06-18  98(1994)    93(1994)   96(1944)    96(1944)   95(1994)    92(2018)
06-19  98(1995)    94(1994)   92(1995)    94(1994)   94(1994)    92(1931)
06-20  98(1953)    94(1988)   96(1988)    95(1933)   95(1933)    92(2016)
06-21  100(2022)   96(1988)   95(2022)    97(1933)   98(1933)    95(1933)

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Heat Advisory until 8 PM EDT Friday for OHZ003-006>014-017>023-
     027>033-036>038-047-089.
PA...Heat Advisory until 8 PM EDT Friday for PAZ001>003.
NY...None.
MARINE...None.

&&

$$

SYNOPSIS...Maines
NEAR TERM...Campbell/Sefcovic
SHORT TERM...Maines
LONG TERM...Maines
AVIATION...26
MARINE...Maines
CLIMATE...