-- Discussion containing changed information from previous version are highlighted. --
448
FXUS61 KCLE 200603
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
203 AM EDT Thu Jun 20 2024

.SYNOPSIS...
Upper level ridge remains in place through this week. A weak
cold front sags southward into northern Ohio and northwestern
Pennsylvania Thursday before lifting back northward as a warm
front Friday. Low pressure system arrives by the end of the
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
8:00 PM Update:
Modest convergence over Northwest OH has led to a few strong to
severe, slow-moving thunderstorms this evening. Isolated
damaging winds and locally heavy rain are the main concerns.
Activity will gradually subside by later this evening. No major
changes were needed with this update.

Previous Discussion:
Unseasonably warm and moist environment continues as a ridge of high
pressure remains draped over the region. This air mass has allowed
for another day of strong diurnal heating leading to MLCAPE values
to rise to 2500+ J/kg and pop up thunderstorms to develop along the
Indiana/Ohio border this afternoon. Primary concern as these storms
build east into Northwest and North Central Ohio remains to be
damaging wind gusts, though enhanced shear this afternoon may lead
to instances of hail and/or a tornado. As with convection this past
week, expect for thunderstorms to diminish in intensity and
coverage this evening as we lose daytime heating.

The ridge sinks south as a weak cold front enters the region from
the north. We won`t see much relief from the heat and convection as
the front sags south of Lake Erie on Thursday. Still well above
normal with high temperatures rising into the upper 80s to
lower 90s accompanied by dew points near 70 degrees. Anticipate
for scattered thunderstorms to develop along the cold front
Thursday afternoon. Overnight lows tonight and Thursday night
will settle in the upper 60s to lower 70s.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
Upper ridge retrogrades to the west over the Mississippi Valley by
Friday. The weak frontal boundary is expected to have stalled across
inland areas with a light northerly flow across most of the area.
Locations downwind of Lake Erie in NE Ohio and NW Pennsylvania will
see temperatures drop back into the 80s while inland areas remain in
the low 90 to mid 90s. May be able to consider dropping a few
counties in our northeastern area from the Heat Advisory but will
probably be needed again by Saturday so will hold off on any changes
at this time.

Moderate instability will remain along the stalled boundary on
Friday and scattered thunderstorms are possible again. A limiting
factor will be if the boundary pushes south of the area or if
dewpoints drop off more than expected. The boundary pushes back
north as a warm front on Saturday ahead of low pressure moving into
the Upper Great Lakes. Heat indices rebound into the 95-100 degree
range for all areas although with a little more mixing and lower
humidity. Chance of thunderstorms should be a little lower on
Saturday except perhaps if a lake breeze develops in NE Ohio and NW
Pennsylvania.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Low pressure will pass north of Lake Huron on Sunday ahead of a
trough dropping into the Upper Midwest and Great Lakes. Showers and
thunderstorms are expected to develop ahead and along the cold front
that is forecast to move through the area during peak heating. While
the instability may not be as high as some of the previous days this
week, forcing along the front will be better and would expect some
potential for strong to severe thunderstorms.

Monday does bring some relief from the heat as high pressure builds
into the Great Lakes and humidity drops off. The respite is pretty
short lived as some amplification of the upper level ridge occurs on
Tuesday. The ridge axis is positioned over the Plains through the
middle of next week and a lower confidence aspect of the forecast is
if some more organized complex of thunderstorms rounds the ridge and
approaches the local area. The GFS and Canadian both show something
passing near but just west of our area Tuesday into Wednesday which
is more realistically where the higher instability will be
located.

&&

.AVIATION /06Z Thursday THROUGH Monday/...
-- Changed Discussion --
Showers and storms persist across Lake Erie this morning with a
trajectory just north of KERI. Still worth a brief VCTS mention,
but impacts at the terminal seem minimal outside of any brief
wind shift with an orphaned outflow boundary. High clouds remain
across the region from Wednesday`s convection and will continue
into the morning hours today. New diurnal cumulus will form
during the early afternoon hours, starting in NW OH and NW PA,
eventually expanding across the rest of northern Ohio. There
will be new afternoon storm chances later Thursday afternoon and
have some VCTS mentions at KYNG, KTOL, and KFDY to highlight
scattered TS in those corners of the airspace. However,
confidence in location and coverage are still fairly limited. TS
chances and diurnal cumulus will wane during the evening hours.
Winds will be very light through the period with variable
direction. Southerly flow will be favored through daybreak
before westerly winds begin inland and more northerly flow
becomes more favored off a modified lake breeze in the northern
terminals.

Outlook...Isolated to scattered thunderstorms and non-VFR
conditions are possible again Friday afternoon. More organized
thunderstorms with non-VFR conditions possible Sunday afternoon.
-- End Changed Discussion --

&&

.MARINE...
Good marine conditions with winds of 10 knots or less will continue
through Friday. The main concern will be gusty winds associated with
any thunderstorms that develop on the lake which could exceed 40
knots. Southwest winds increase to around 10 knots Saturday and 10
to 20 knots by Sunday ahead of the front, shifting to west behind
the front later Sunday. Waves build to 2 to 4 feet across the mid-
section of the lake and will monitor for any strengthening for
possible Small Craft Advisory conditions. Onshore winds of 10 to 15
knots will continue on Monday as high pressure builds over the
Central Great Lakes.

&&

.CLIMATE...
-- Changed Discussion --
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 Thursday, June 19 to Sunday,
June 23 are listed below for our official climate sites.

Date   Toledo     Mansfield   Cleveland   Akron     Youngstown   Erie
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)
06-22  99(1988)    95(1988)   98(1988)    97(1988)   97(1933)    94(1988)
06-23  96(1911)    91(1964)   94(1948)    94(1923)   94(1943)    92(1964)
-- End Changed Discussion --

&&

.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...Iverson
NEAR TERM...Iverson/Sullivan
SHORT TERM...KEC
LONG TERM...KEC
AVIATION...Sefcovic
MARINE...KEC
CLIMATE...CLE