204
FXUS61 KCLE 281115
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
715 AM EDT Fri Jun 28 2024

.SYNOPSIS...
A warm front will push through and north of the area today. A
cold front will approach the area from the west on Saturday and
cross the area on Saturday night. High pressure will build from
the west for Sunday into Monday.

&&

.NEAR TERM /THROUGH SATURDAY/...
Returns on the radar this morning are not amounting to much of
anything this morning as mid level clouds are moving into our
dry forecast area and not much is reaching the surface. Have
kept dry PoPs despite returns in NW OH and northern Indiana.

Previous Discussion...
Today will be a return to normal across the forecast area with a
warm front pushing north across the area and return flow coming
back to the region. Temperatures will rise back into the 80s and
dew points will slowly recover through the day into the low-to-
mid 60s by nightfall. High clouds will be floating through the
region today and will obscure full sunshine and the full
potential of the warm sector and light southeast flow will be
present today. A modified lake breeze will impact areas very
close to the lakeshore, but believe there is enough of a
pressure gradient in place to prevent much inland movement.

Unfortunately, the moisture spigot continues through the night
and dew points will get rather juicy into the upper 60s and
lower 70s by daybreak on Saturday. The strong isentropic lift
across the region tonight should allow for showers and
thunderstorms to develop through the night with the greatest
coverage by daybreak. Also helping shower and storm coverage
will be a 45 kt low level jet at 850 mb that will be moving
through the region after midnight and could inflame convection
across the forecast area. For now, do not believe that
convection overnight will be severe as there is not a lot of
instability to work with and storms may be elevated. However,
these showers and storms may prime the area with an initial
round of rain that could have repercussions for Saturday. With
warm advection, clouds, and rain in the region, believe that
lows will be in the upper 60s to lower 70s with most areas
likely staying above 70.

The Saturday forecast continues to be a very active weather day
across the region with appreciable threats with both severe
weather and flash flooding. A strong southwest to northeast
oriented 850 mb low level jet with southwest flow parallel to a
surface cold front moving southeast will be the main culprits
for both threats. For the severe weather threat, the main 850 mb
jet will be departing to the northeast by the late afternoon and
early evening hours. The right entrance region will be over the
eastern half of the forecast area during this time and could
offer great support for severe storm development in this region.
The wind shear values across the area on Saturday afternoon are
rather impressive for late June with 0-6 km bulk shear values of
50 to 55 kt and 0-3 km SRH over 200 m2/s2 in the entrance
region of this low level jet. Therefore, storms have a great
chance to become organized for all severe weather hazards,
especially if some supercell thunderstorms can form. A 5%
tornado probability has been introduced in the Day 2 Severe
Weather Outlook, as that threat is beginning to look more
intriguing with some convective model output showing the sig tor
parameter over 1 in the eastern portion of the forecast area.
However, there is one big concern for the entire severe weather
setup - instability. Showers and storms are likely to be ongoing
across the region on Saturday morning and with the low level
jet overhead offering support, these will likely persist
through the day. Any break in shower and storm activity and
especially any breaks in the clouds could spell trouble as there
will be opportunity for larger amounts of surface based
instability to form in the region. Surface dew points will be
trending upward during the day on Saturday into the 70s with the
efficient moisture advecting into the region, so it won`t take
much warming to get appreciable CAPE. However, instability is
the limiting factor for the severe threat and why a Day 2 Slight
Risk for severe weather is appropriate at this time. The hail
threat on Saturday will also be limited to just supercell
development at this time. Wet bulb zero values are at 13k ft and
higher and will allow for melting hail (and flooding, more
next!) vs. observed severe hail. The Slight Risk now
incorporates almost the entire forecast area as there is enough
shear to be concerned everywhere. However, the eastern counties
have the greatest concern at this time with the highest shear
and best chance at getting a late morning break in rain and
could be a candidate for future upgrades, depending on
convective trends tonight into Saturday.

While the severe threat is trending upward across the forecast
area, the flash flooding threat is also increasing across the
region. Rain late tonight into Saturday will help prime the area
with some water to reinvigorate a relatively dry region. Most
areas received rain on Wednesday that was quickly absorbed, and
this initial round should allow for a few tenths to an inch or
so of rain to prime the area ahead of more potent rainfall
rates later on Saturday. Coincident with the timing of
Saturday`s severe weather threat during the afternoon and
evening are also some pretty good parameters for flash flooding
in the region, precipitable water values near/above 2 inches
will be near/above daily maximums for the region, wet bulb zero
values over 13k ft will allow for more melting hail and heavier
rainfall in thunderstorms, the southwest flow of the 850 mb jet
is parallel to the surface cold front and it will be likely that
storms train over the same areas until the storms are pushed
out of the area Saturday night with the cold front. With that,
QPF has been raised considerably across the entire forecast
area, especially the southeast areas, where more convective
cores are expected. For these areas, have contours of 2+" of
rain in the forecast and it is likely that this will occur
quickly, posing a flash flood threat, especially in urban and
poor drainage areas. This area is also under a Day 2 Slight Risk
for Excessive Rainfall to highlight the flood potential.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
Cyclonic W`erly flow aloft and embedded shortwave disturbances
affect our CWA Saturday night as a cold front sweeps SE`ward through
northern OH and NW PA. Behind the front, a low-level ridge builds
from the north-central U.S. and vicinity. Additional
scattered/organized showers and thunderstorms with periods of
torrential rainfall are expected along and ahead of the cold front
as the warm/very moist sector boundary layer remains weakly to
moderately unstable amidst moderate to strong deep layer bulk shear.
Given the projected thermodynamic/kinematic environment, strong to
severe thunderstorms and localized flash flooding remain a concern
beyond sunset. The shower/storm threat will end from northwest to
southeast with the passage of the front and fair weather is expected
CWA-wide by daybreak Sunday morning as stabilizing subsidence
accompanies the building ridge. Low-level CAA behind the front will
contribute to lows reaching the 60`s around daybreak Sunday.

Fair weather is still expected on Sunday through Monday as the low-
level ridge continues to build from the north-central United States
and vicinity and is accompanied by stabilizing subsidence and net
low-level cold/dry air advection. Simultaneously and farther aloft,
cyclonic W`erly to NW`erly flow and embedded shortwave disturbances
eventually give way to a ridge building from the Great Plains. Late
afternoon highs are expected to reach the upper 60`s to upper 70`s
on Sunday and Monday, respectively. Overnight lows should reach the
50`s to lower 60`s around daybreak Monday.

Net albeit weak low-level WAA is expected to develop across our CWA
Monday night as the core of the low-level ridge begins to exit
toward New England and the ridge aloft crests E`ward over/near our
CWA. Fair weather persists as stabilizing subsidence continues to
affect our region. Overnight lows should once again reach mainly the
50`s to lower 60`s around daybreak Tuesday since partially clear
sky, limited low-level humidity, and weak surface winds are expected
to promote efficient nocturnal cooling Monday evening through
daybreak Tuesday.

&&

.LONG TERM /TUESDAY THROUGH THURSDAY/...
Tuesday is still expected to feature fair weather as high pressure
at the surface and aloft exits slowly E`ward, yet associated
stabilizing subsidence persists over/near the eastern Great Lakes
and Upper OH Valley. Continued net WAA along the western flank of
the low-level ridge will contribute to late afternoon highs reaching
the upper 70`s to lower 80`s in NW PA and the 80`s in northern OH.

Cyclonic W`erly flow aloft and embedded shortwave disturbances
affect our region Tuesday night through Wednesday night as surface
troughing becomes established across northern OH/NW PA. A warm front
will sweep N`ward through our region Tuesday night and usher-in a
much warmer/more humid air mass originating over the Gulf of Mexico.
In addition, a cool front is still expected to sweep generally
SE`ward through our region Wednesday night and usher-in a slightly-
cooler and less-humid air mass. The lifting mechanisms (i.e.
shortwave disturbances/attendant surface trough axes and fronts) are
expected to release weak to moderate instability, including elevated
instability, to trigger periodic showers/thunderstorms. Moderate
deep layer bulk shear will allow convection to be organized. Severe
thunderstorms are possible given the projected thermodynamic and
kinematic environment. The best chance for severe thunderstorms is
expected Wednesday afternoon through early evening, when daytime
heating of the warm/moist sector boundary layer will allow MUCAPE to
be maximized. Overnight lows should reach the 60`s to lower 70`s
Tuesday night and Wednesday night, respectively. Daytime highs on
Wednesday should reach the 80`s to lower 90`s.

Additional periods of showers/thunderstorms are expected on Thursday
(July 4th) through Friday as W`erly flow aloft and embedded
shortwave disturbances affect our region, net surface troughing
persists, and the aforementioned front wavers in a generally south-to-
north manner and vice versa, in vicinity of our CWA, in response to
the aforementioned shortwave trough passages. Daytime highs are
expected to reach the 80`s on Thursday and Friday, respectively, and
overnight lows are expected to reach the 60`s to lower 70`s around
daybreak Friday morning as the front will separate a warmer/more
humid air mass to the south from a slightly cooler/less humid air
mass to the north.

&&

.AVIATION /12Z Friday THROUGH Tuesday/...
VFR conditions are expected for the first half to two-thirds of
the TAF period. High clouds across the region will thicken
today as a warm front moves across the airspace and north of the
area. East to southeast flow will be favored across the area
today. Some form of a lake breeze may develop but confidence in
the boundary reaching KERI or KCLE is low. Increasing moisture
across the region and a cold front approaching from the
northwest for Saturday will allow for mid-level clouds to enter
the region this evening. Convection will move in largely after
midnight with coverage increasing through the night. Have VCTS
to TS mentioned across the TAF sites with conditions
deteriorating to MVFR. There could be windows of moderate to
heavy rain with the TS toward daybreak on Saturday and TAFs may
need to be refined to a more pessimistic IFR as confidence in
timing increases.

Outlook...Non-VFR possible in widespread showers and
thunderstorms on Saturday and Saturday night.

&&

.MARINE...
Winds around 5 to 15 knots vary between SE`erly and NE`erly today as
a ridge affects Lake Erie and the parent high pressure center moves
from the Lake Ontario region to Atlantic waters near Nantucket.
These winds are expected to trend onshore (i.e. NE`erly) late this
morning through early evening courtesy of lake breeze development.
NE`erly to SE`erly winds around 5 to 15 knots veer to S`erly and
freshen to 10 to 20 knots tonight as the ridge exits E`ward and a
warm front sweeps N`ward across Lake Erie. Waves remain mainly 3
feet or less, but occasional 4 footers develop in open U.S. waters
of the central and eastern basins tonight. Given these very marginal
conditions, the need for a Small Craft Advisory is not expected.

S`erly to SW`erly winds around 10 to 20 knots on Saturday veer to
NW`erly Saturday night as a strong cold front sweeps SE`ward across
Lake Erie and is followed by a building ridge. During the day on
Saturday, waves are forecast to vary from 3 feet or less in
nearshore U.S. waters to 3 to 6 feet in open U.S. waters. Following
the passage of the cold front, waves as large as 3 to 6 feet are
expected in nearshore and open U.S. waters, especially east of The
Islands. A Small Craft Advisory will likely be needed.

NW`erly winds around 10 to 20 knots veer gradually to N`erly on
Sunday through Sunday night as the aforementioned ridge builds from
the Upper Midwest and western Great Lakes. Waves as large as 3 to 5
feet are expected, especially east of The Islands. N`erly winds
around 5 to 15 knots are expected to veer gradually to SE`erly on
Monday through Tuesday as the ridge continues to impact Lake Erie
and the parent high pressure center moves from the western Great
Lakes toward Atlantic waters near NJ. Waves are expected to subside
to 3 feet or less.

&&

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

&&

$$

SYNOPSIS...Sefcovic
NEAR TERM...Sefcovic
SHORT TERM...Jaszka
LONG TERM...Jaszka
AVIATION...Sefcovic
MARINE...Jaszka