765 
FXUS61 KCLE 211103
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
703 AM EDT Fri Jun 21 2024

.SYNOPSIS...
An upper level ridge will continue to slide southwest, away from
the area, today into Saturday. Low pressure will develop over
the Upper Midwest on Saturday and slide across the Great Lakes
on Sunday, extending a cold front across the area. High pressure
will build across the region for Monday.

&&

.NEAR TERM /THROUGH SATURDAY/...
Low stratus and fog hover around Northwest Ohio this morning,
where better moisture remains after showers and storms on
Thursday evening. This area will become better suited for shower
and storm development by late morning/early afternoon and have
bumped up the timing for scattered showers and storms in the
Toledo area. Otherwise, the forecast remains on track at this
time.

Previous Discussion... 
The near term forecast forecast continues to sound like a 
broken record. An upper ridge across the region will continue to
support above normal temperatures with high dew points in the 
upper 60s to lower 70s through Saturday. This air mass will 
continue to allow for heat stress on people and infrastructure 
with heat index values near 100 and the environment remains 
supportive for isolated to scattered showers and storms. 

For today, temperatures will be slightly tapered from the past 4
days with a subtle boundary laced across the southern Lake Erie
shoreline. With a slightly modified lake breeze during the
afternoon hours, this could push slightly inland and keep
temperatures a few degrees lower and offer some very light
refreshment from the days of heat. Meanwhile, with some mixing 
across the region, dew points across the area have fallen off 
just a bit with some low to mid 60s into NE OH and NW PA, 
allowing for heat index values likely staying in the low to mid 
90s. However, with the boundary sagging south during the
afternoon, this could be a focus area of isolated to scattered
convection. It appears that the best chance for storms could be
NW OH once again as the boundary will be hung up in that region
and there will be some moisture convergence and air temperatures
approaching convective temperatures to help convection to get
going. The other favored area will be interior Northeast Ohio
for areas from Wooster to Youngstown and south, but less warm
temperatures could hinder some coverage. Temperatures will fall
again into the upper 60s and lower 70s tonight with dry
conditions in a stable air mass.

For Saturday, the upper ridge is pushed pretty far south and
more zonal flow develops across the Great Lakes region. This may
actually allow for more mixing across the entire forecast area,
so daytime winds may be up a bit, but dew points may be down,
which may sufficiently hinder shower and storm development. Less
mixing in interior NE OH and NW PA may allow for some isolated
showers and storms but probability seems very low. With less of
a blocking ridge aloft, some even warmer air could advect into
the area and temperatures on Saturday should return to the
widespread 90s and heat index values will once again meander
close to 100 degrees.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
A brief trough will push east across a primarily zonal upper level 
flow during the short term period, briefly shifting the weather 
pattern from the ongoing pattern. An associated surface low is 
expected to track northeast through the Great Lakes region which 
will move a cold front east on Sunday. Models suggest a bit of a 
slow down in the progression of this boundary which will allow 
temperatures to climb into the mid to upper 80s on Sunday. The 
timing of the frontal passage now looks to be during a more 
diurnally favorable time with modeled MUCAPE values climbing to near 
1500 J/kg. The one limiting factor on Sunday is that widespread 
clouds are expected, but if areas see breaks in clouds, expect the 
instability to be a bit higher. With this potential widespread 
convection on Sunday, the primary concerns remain damaging wind 
gusts, although large hail and an isolated tornado cannot be ruled 
out given the shear and helicity values in models. In addition, a 
deep warm cloud layer and PWAT values near 2" will result in 
extremely efficient rainfall within these storms. Localized flooding 
may be possible, especially in areas that receive the strongest 
storms. To highlight this severe weather potential, SPC has issued a 
Day 3 Marginal Risk for severe weather for areas along and east of I-
71 and WPC has issued a Marginal ERO for far eastern OH and NW PA. 

The cold front will settle southeast of the area late Sunday night 
and allow for the remainder of the short term period to be dry as 
high pressure again builds in. Although it is a cold front moving 
through, it will not impact temperatures all that much with Monday 
highs still expected to climb into the upper 80s for areas west of 
I71, but will be a tad cooler east only climbing into the upper 70s 
to low 80s. Overnight lows both nights will be a bit cooler dropping 
into the mid 60s both nights.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
High pressure will remain over the area on Tuesday , keeping 
conditions primarily dry but also increase temperatures also into the 
mid 90s for western counties and mid 80s for eastern counties. There 
is a potential for afternoon convection to develop given enough 
moisture and instability and the positioning of the area within the 
warm sector. By Tuesday night, models diverge quite a bit in what 
will happen for the remainder of the long term period. The ECMWF 
suggests a broad upper level trough that moves across the northern 
Great Lakes with an associated weak cold front pushing east on 
Wednesday. The GFS and Canadian however suggest a deeper upper level 
trough extending over the eastern US with a surface low over the 
Mississippi River Valley and another over the Great Lakes region. 
Although the driving mechanisms are different amongst models, there 
looks to be a consistent chance of showers and storms on Wednesday 
into Wednesday night before high pressure returns and dries out the 
area for the end of the long term period. 

Tuesday looks to be the warmest day during the long term period with 
temperatures gradually cooling to the low to mid 80s by the end of 
the period. Overnight lows will follow a similar pattern with 
temperatures falling into the upper 60s to low 70s Tuesday night, 
but then cooling into the upper 50s to low 60s by Wednesday night.

&&

.AVIATION /12Z Friday THROUGH Tuesday/...
Low clouds and fog have persisted across Northwest Ohio this
morning after showers and storms last night with a continued
moist, stable boundary layer. These should lift with sunrise
this morning. Another warm and unstable day will allow for some
iso/sct storms with the edges of the airspace being the most 
favored once again with TS mentions in the vicinity of KTOL, 
KFDY, and KYNG. Afternoon cumulus should also fill in across the
region. Any shower/storm threat and cumulus should fade with 
sunset and have conditions returns to just high clouds and light
winds. Winds will favor a west to northwest direction for the 
day. Return flow will return to the region for Saturday with
southerly flow across all terminals.

Outlook...Thunderstorms will increase in coverage Sunday 
afternoon with non-VFR conditions possible.

&&

.MARINE...
A stalled boundary will linger near the southern shore of Lake Erie 
today, allowing for generally light and variable winds with the 
exception of locally high winds and waves in the afternoon and 
evening with any thunderstorms that develop. Winds will increase to 
10-15 knots from the southwest on Saturday as a warm front lifts 
north of Lake Erie and a cold front approaches from the west. On 
Sunday, the aforementioned cold front will move east across the 
area. Winds will briefly increase from the southwest to 15-20 knots 
ahead of the boundary, gradually shifting to the northwest and 
weakening to 10-15 knots by Sunday night. This period on Sunday 
looks to be the next potential time for a Small Craft and Beach 
Hazard needed, but with uncertainty lingering in the timing of the 
front, will continue to monitor. High pressure returns late Monday 
through Tuesday, allowing winds of 5-10 knots to gradually shift and 
gain more of a southerly component. Generally winds will remain from 
the south-southwest through Wednesday as high pressure lingers 
before shifting to gain more of a northerly component on Thursday. 
Models diverge in timing of boundaries past Wednesday, so will need 
to continue to monitor those trends in the coming updates.

&&

.CLIMATE...
The records for Friday, June 21 through Sunday, June 23 are listed 
below for our official climate sites. 

Date   Toledo     Mansfield   Cleveland   Akron     Youngstown   Erie                
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)

&&

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

&&

$$

SYNOPSIS...Sefcovic
NEAR TERM...Sefcovic
SHORT TERM...Campbell
LONG TERM...Campbell
AVIATION...Sefcovic
MARINE...Campbell
CLIMATE...CLE