655
FXUS61 KCLE 281956
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
356 PM EDT Fri Jun 28 2024

.SYNOPSIS...
Low pressure will track from the northern Plains into the
northern Great Lakes tonight, lifting a warm front through the
region by Saturday morning. A trailing cold front will sweep
across the region Saturday night into Sunday morning as the low
tracks into Quebec. High pressure will build into the region
Sunday and Monday before moving east Tuesday.

&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
Very active weather is still expected late tonight and Saturday with
areas of heavy rainfall as well as a few severe storms likely. The
heavy rain and flooding threat is still higher confidence than the
severe weather threat, but there is uncertainty regarding where the
heaviest, most persistent thunderstorms may set up. See details
below.

Water vapor loops this afternoon show a strong mid/upper shortwave
trough and associated closed low moving from the northern Rockies
into the northern Plains. This shortwave will progress into the
northern Great Lakes late tonight and Saturday morning before
becoming absorbed into a broader mid/upper trough digging down
across the Great Lakes by Sunday. The associated surface low,
currently over northern Minnesota, will cross the UP of Michigan
tonight before exiting into Quebec Saturday night, dragging a strong
cold front through the region Saturday night into Sunday morning.
Upstream radar and surface observations show a sign of what`s to
come late tonight and Saturday, with strong warm/moist advection
bringing dew points into the 70s in the warm sector across a large
area of the corn belt, as well as widespread showers and elevated
thunderstorms driven by isentropic ascent ahead of the warm front.
This warm front will slowly lift east-northeastward across the
region tonight into Saturday morning, with strong warm/moist theta e
advection tapping into the aforementioned rich low-level moisture to
the west and southwest. Expect dew points to rise quickly this
evening and tonight, with most dew points touching 70F by 12Z
Saturday. There is no doubt that the environment will become juicy
in a hurry, but the location of the heaviest, most widespread axis
of convection is uncertain.

Regarding heavy rain/flooding details, A 40-50 knot west-
southwesterly low-level jet will feed high theta e air and elevated
instability into the region, with associated isentropic ascent
driving elevated convection ahead of the slowly lifting boundary,
but CAMS are struggling to pinpoint where the best axis will set up.
There is a wide range of possibilities from over Lake Erie to over
the southern and eastern tier of counties, so held off on a Flood
Watch for now given the uncertainty. What is certain is that any
thunderstorms late tonight and Saturday morning will contain highly
efficient (torrential) rainfall rates given PWATs rising to 2 to 2.3
inches (maximum daily value of climatology), very deep, saturated
warm cloud depths, and low LCL heights of 400-800 m to minimize
evaporation. CAMS suggest some training or repeated rounds of
convection is possible before the warm frontal boundary lifts NE,
and with the aforementioned environment supporting rainfall rates in
excess of 3 inches per hour, flash flooding is likely in areas that
see training or multiple rounds despite current 3 and 6 hour FFG`s
being high. Will wait to see where the axis starts to set up tonight
to determine where the greatest flooding threat will be, but heavy
rainfall rates are possible anywhere.

Regarding the severe weather potential Saturday afternoon and
evening, this is far more conditional and uncertain. As the warm
frontal boundary lifts ENE across the region Saturday morning, it is
likely to slow over NE Ohio and NW PA. NAM and RAP forecast
soundings and plan views suggest impressive veering with height near
the boundary leading to curved hodographs and 300-400 m2/s2 of low-
level (0-1Km) SRH. This along with low-level shear of 30+ knots and
deep layer effective shear of 40-50 knots in the morning near the
warm front could support an isolated tornado or two, aided by the
low LCL heights as well. However, instability and time of day are
the biggest limiting factors. Forecast soundings suggest elevated
CAPE over 1000 J/Kg but very little SBCAPE available, so it`s
possible that we just see some elevated rotation along with heavy
rainfall. If severe weather occurs, there is a better chance for the
afternoon and evening as the area gets fully into the warm sector
behind the warm front. Latest CAMS are suggesting a lull most of the
afternoon which could allow for breaks in the overcast and greater
heating/instability. If this occurs, then scattered severe
thunderstorms will redevelop ahead of the cold front and move across
the region from NW to SE during the afternoon and evening. These
storms could produce damaging winds, an isolated tornado or two, and
additional heavy rainfall given deep layer shear staying marginally
favorable (30-35 knots) along with marginally favorable low-level
shear of 20+ knots and low-level SRH of 100-200 m2/s2. However,
there is uncertainty in how much redevelopment will occur since
there could be extensive cloud cover and outflow lingering from the
morning convection. Some CAMS show very little redevelopment or
redevelop the convection SE of the area. At this time, the SWODY2
slight risk still looks reasonable given the shear that could
potentially take advantage of greater heating, but again, very
conditional.

Any showers and thunderstorms will quickly end from NW to SE
Saturday night as the cold front passes through the region and drier
air works in behind it thanks to broad surface high pressure over
the Upper Midwest.

Highs Saturday will range from the low/mid 80s in most areas, but
more precip could keep NW PA and NE Ohio in the upper 70s to around
80. It will be oppressively humid with dew points in the low to mid
70s. The cooler air will start to come in Saturday night with lows
in the low to mid 60s.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
An upper level trough will be over the Great Lakes region extending
into southern Ontario and Quebec during the later part of the
weekend. High pressure at the surface will be centered over the
Upper Midwest on Sunday slowly building into the region. Cooler air
will advect in with a northwesterly flow Sunday. There will be mix
of sun and clouds across the area with more cloud cover down
downwind of Lake Erie. There also could be a few isolated lake
effect rain showers early Sunday morning before the atmosphere dries
out. Afternoon temperatures will reach the lower and middle 70s on
Sunday.

High pressure will continue to build over the region Sunday night
into Monday. Skies will clear out Sunday evening and overnight low
temperatures will fall into the lower 50 middle 50s away from the
immediate lakeshore. Monday will be very nice day with plenty of
sunshine and light winds with the center of high pressure nearby.
Afternoon temps will be in the lower to middle 70s Monday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
A summertime ridge of high pressure will develop across the Lower
Ohio Valley and Mid-Mississippi River Valley regions by the middle
of next week. Our area will be on the edge of this ridge. Southerly
flow will return on Tuesday with a return to summer like
temperatures climbing into the middle and upper 80s. The humidity
will also start returning Tuesday into Wednesday. A shortwave trough
will move through the Upper Great Lakes region on Wednesday with a
trailing cold front. Wednesday will likely be the hottest day of
next week with temperatures reaching the upper 80s and lower 90s. A
weak cold front will move into the area next Wednesday night with
scattered showers and thunderstorms. This frontal boundary may stall
out from west to east over Ohio Thursday into Friday with multiple
rounds of showers and storms possible towards the end of next week.
High temperatures will remain in the middle to upper 80s late next
week.

&&

.AVIATION /18Z Friday THROUGH Wednesday/...
VFR will continue the rest of today into tonight, but cigs will
gradually lower this evening and tonight as a warm front and
associated showers and thunderstorms approach from the west.
There is a fairly consistent signal for widespread showers and
thunderstorms late tonight into Saturday morning, but uncertain
in where the heaviest and most widespread axis of thunderstorms
will set up. Any thunderstorms will produce torrential rainfall
rates and resultant low cigs and vis. At this time, stayed with
widespread showers/storms and MVFR conditions spreading in from
west to east in the 06-12Z timeframe. IFR is possible at times
as well, but this will all be fine tuned once we see where the
axis sets up. There will be a solid warm sector behind the warm
front late Saturday morning through the afternoon, and this is
leading to far less coverage of showers/storms during the
afternoon than previously thought, so kept precip mentions to
VCSH in the afternoon with cigs improving to VFR for sites along
and west of I-71.

S winds of 5-10 knots this evening into early tonight will
become SW and increase to 10-20 knots late tonight and Saturday
morning with gusts of 20-25 knots at times.

Outlook...Non-VFR possible in showers and thunderstorms
Saturday afternoon into Saturday night. Non-VFR possible in
showers and thunderstorms Tuesday night and Wednesday.

&&

.MARINE...
Southerly, offshore flow will continue at 10 to 15 knots tonight.
The flow will become southwesterly on Saturday and increase 15 to 20
knots ahead of an approaching cold front. The front will move across
Lake Erie Saturday evening. Winds will shift from the northwest and
onshore around 15 knots Saturday night through Sunday afternoon. We
could briefly reach SCA conditions for a few hours Saturday night
into Sunday behind the front but confidence is uncertain at this
time. Waves will be higher along the lakeshore by Saturday evening
and overnight. High pressure will build in Sunday night into Monday.
Winds will be northerly Sunday night 10 to 15 knots. On Monday,
winds will shift from the northwest around 10 knots becoming light
and variable by Monday evening. South to southeasterly winds around
10 knots will return on Tuesday and further increase 15 to 20 knots
from the southwest by next Wednesday.

&&

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

&&

$$

SYNOPSIS...Garuckas
NEAR TERM...Garuckas
SHORT TERM...Griffin
LONG TERM...Griffin
AVIATION...Garuckas
MARINE...Griffin