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000
FXUS61 KCLE 170018
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
818 PM EDT Tue Apr 16 2024

.SYNOPSIS...
Low pressure over the Central Plains will lift a warm front
north across the region tonight into Wednesday. This system
will then extend a cold front east through the area by Wednesday
evening. Another cold front will cross the region towards the
end of the week. High pressure will return for the weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY NIGHT/...
8:15 PM Update:
Made a few tweaks to the forecast this evening. Decreased POPs
slightly tonight and Wednesday morning. Do expect a batch of
showers/thunder to lift through and bring rain to most of the
area early Wednesday, though models disagree on the exact
coverage/organization of this activity, so favored "likely"
wording over categorical (80%+ POPs) wording. Also decreased
POPs slightly, mainly across southwestern counties, for
Wednesday afternoon/early evening with the cold front. Hi-res
guidance disagrees on coverage of storms with the cold front
farther south across our CWA, possibly due to the strongest
forcing lifting towards Michigan/southern Ontario with a bit of
subsidence behind the weak morning shortwave and associated
precip. Given this, maintained a brief period of categorical
(80%+ POPs) wording from Northwest OH east towards Cleveland,
and then expanding into much of Northeast OH and Northwest PA
with the cold front, though opted for "likely" wording farther
southwest. Also bumped up wind gusts Wednesday afternoon,
especially across Northwest and North Central OH, as a period of
sunshine and deep mixing into a solid 35-40kt low-level jet
should allow for 30-40 MPH wind gusts, especially west of I-71.

Regarding the severe weather threat with the cold front
Wednesday afternoon and evening, feel that a Slight Risk (risk
level 2/5) for some combination of all severe hazards (wind,
hail, a tornado or two) is a fair assessment of the overall
threat at this time. Taking a close look at guidance and
trends, am concerned that the deeper mixing could help to
straighten out the low-level hodographs and raise LCL heights,
with the possible exception of far eastern OH and PA. This could
act to limit the tornado threat a bit, though with all guidance
suggesting a 40-50 knot 700mb jet there will still be enough
bulk/speed shear for organized convection so don`t want to rule
out a tornado or two. Another concern is that there is
disagreement among guidance with regards to if a shortwave
moving through moves east across our area, or lifts more towards
Michigan and southwestern Ontario. If the shortwave (forcing)
lifts into MI/ON, that could somewhat delay initiation and
limit coverage of storms farther south/southwest in the area.
Overall, most guidance still has at least scattered storms (if
not a line) affecting most of the area with sufficient
instability and shear for a wind, hail, and possible tornado
threat, but do want to point out possible limiting factors or
uncertainty that are evident in guidance this evening.

Previous Discussion:
An active near term period is in store across the region with
confidence in strong to severe thunderstorms increasing for
Wednesday afternoon and evening. All hazard types are possible,
including large hail, a couple of tornadoes, and damaging wind
gusts.

For this evening and overnight, surface observations indicate a
warm front trying to lift north across the OH Valley, although
it is encountering a stubborn lake breeze which has already made
it to roughly the US-30 corridor, enhanced by exiting high
pressure across New England. A few isolated showers/storms could
scrape the far southwest tier of the area through this evening.
Otherwise, a pre-frontal trough is expected to arrive overnight
which will eventually force the warm front north across the area
and result in scattered to widespread showers with perhaps a few
rumbles of thunder resulting from marginal elevated instability.

Behind the morning convection, anticipate rapid recovery to
occur in the vicinity of Indiana and Ohio, indicated by a 40 to
50-knot SWerly 700 mb jet punching into the region. The dry air
associated with the 700 mb jet is likely a result of large scale
subsidence on the back side of the occluded low across the Upper
Midwest. The latest HREF is suggesting mean MLCAPE values around
1000 J/kg with 35 to 40 knots of bulk shear, most of which is
contained within the 0-3km layer. Hodographs are fairly
impressive, especially below 700 mb with clockwise- curved
profiles. Mean-layer shear vectors oriented SWerly should aid in
sustaining bowing segments with embedded circulations and/or
semi- discrete cells as they move west to east across the area.
In terms of timing, anticipate a 2-6 PM window generally along
and west of the I-71 corridor and a 6-10 PM window east of the
I-71 corridor.

A small concern will be the heavy rain threat, although given
PWATS of 1 inch or less and the fairly progressive easterly-
moving storms, believe the flash flooding threat remains low.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
Thursday night cold front will be a significant airmass change for
the region with showers and storms as it passes west to east through
the CWA. Expecting a low level jet and modest deep layer shear, but
somewhat lacking in the instability above the boundary layer. Still
should see storms, but there does not appear to be much of a severe
threat at this point which could change with any appreciable
increases in instability. 850mb temperatures in the mid teens will
plummet behind the front through the remainder of the short term
forecast period. Likely to get a secondary reinforcement to the
colder air late Friday night into early Saturday and those low level
temperatures dropping below 0C. Northwest winds prevail through the
period at 15-25mph gusting to 30mph behind the initial cold front.
Mid 60s to lower 70s Thursday become upper 50s to lower 60s
Friday.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
In the wake of the second cold front, temperatures continue to fall,
and looking at a not so favorable weekend with the coolest air of
the 7 day forecast. Temperatures Saturday and Sunday in the upper
40s to lower 50s, and mainly dry through Monday. Concerns arise
Saturday night and Sunday night with the overnight low temperatures
in the frost/freeze range. With the growing season started across
northern Ohio and northwest Pennsylvania, may need headlines for
these overnight periods.

&&

.AVIATION /00Z Wednesday THROUGH Sunday/...
VFR this evening through most of tonight. A batch of showers and
perhaps some embedded thunder will move west to east across the
area Wednesday morning as a warm front lifts through. At most
sites any restrictions to vsby/ceiling with the showers/thunder
will be brief, though could see brief MVFR ceilings as the warm
front is near a given site. After a dry slot and lull in any
showers / thunder, a cold front sweeps through from west to east
between about 19z at TOL/FDY and 2z at ERI. Another line or
broken line of thunder is expected with this front. Coverage of
storms may be greatest near TOL, CLE, ERI and YNG, though
included at least VCTS for a brief window at all sites. Thunder
potential will quickly exit into Wednesday night as the front
moves east of the area. A few storms may be severe with wind
gusts up to 50kt and up to quarter-sized hail.

Light E winds will gradually turn SE and S tonight, veering SSW
Wednesday morning behind the warm front. Winds will turn more SW
into Wednesday evening behind the cold front. Speeds will
become light this evening, increase to 5 to 12 knots overnight
and 12 to 20 knots with gusts 30 to 35 knots Wednesday
afternoon. Maintained a brief low-level wind shear mention at a
number of sites early Wednesday as a 30-40kt SSW low-level jet
develops over light S-SE surface winds.

Outlook...Non-VFR possible for Friday into Saturday in rain.

&&

.MARINE...
Easterly flow this evening and tonight 15-20kts becomes offshore
later tonight into Wednesday 15-20kts after a warm front pushes
through the region. Nearshore zone wave heights in these areas will
decrease to less than 2ft, increasing away from shore. Winds
southwesterly Wednesday night into Thursday, briefly becoming
southerly 10-15kts late Thursday ahead of a sharp cold front. Winds
then become northwesterly 15-25kts late Thursday night into Friday
behind the cold front with wave heights increasing to 3-5ft in the
central basin.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...Small Craft Advisory until 4 AM EDT Wednesday for LEZ142>146.

&&

$$

SYNOPSIS...Kahn
NEAR TERM...Kahn/Sullivan
SHORT TERM...26
LONG TERM...26
AVIATION...Sullivan
MARINE...26