369
FXUS61 KCLE 160538
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
138 AM EDT Tue Jul 16 2024

.SYNOPSIS...
A frontal boundary will settle across the Lower Great Lakes today
before pushing southeast across the area as a cold front Tuesday
night into early Wednesday. High pressure will build in from the
west Wednesday night through the end of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
1:30 AM Update...
The severe thunderstorm watch has been expanded eastward to
include several counties in Northwest Ohio and the western
basin of Lake Erie. Mesoanalysis suggests there is a still a
good plume of instability (as high as 3000 J/kg of MUCAPE) into
the I-75 corridor. This core of instability is expected to
advance eastward into the forecast area, which should provide a
good amount of buoyancy to the MCV/QLCS that is approaching from
the west. This line is still producing severe weather winds at
the IN/OH state line with numerous reports of severe wind gusts
and damaging winds (mainly tree damage at this point). Even so,
we are generally expecting an overall weakening trend as this
QLCS moves across the area. However, since there is still good
instability and the MCV is likely producing enhanced lift/shear,
it`s quite uncertain how long this QLCS progresses before truly
weakening below severe limits. The current expectation is for
sporadic/isolated severe-level wind gusts within the severe
thunderstorm watch area, before it weakens to sub-severe levels.

Previous discussion...
An active near term period is expected with multiple chances for
thunderstorms through Tuesday. Some storms may be strong to
severe after midnight tonight with the primary threat being
damaging wind gusts.

As of 330 PM, a roughly west to east axis of cumulus exist along
a pseudo warm front, extending from central IA towards
Northwest Ohio. Strong to extreme instability resides along and
just south of this axis, with MLCAPE as high as 4000 to 4500
J/kg in some spots across the Midwest with surface dew points
in the mid to upper 70s. Water vapor imagery reveals a well-
defined upper trough axis arriving across southern MN this
afternoon, with storms beginning to develop along this
instability axis across central IA. Thunderstorms are expected
to increase in coverage across portions of IA/IL/southern WI
through this afternoon, roughly following this instability axis
east- southeastward. Anticipate this axis to slowly drift
northwards through the rest of this afternoon and evening,
reaching roughly the Lake Erie/southern MI vicinity ahead of the
approaching complex which is expected to arrive just after
midnight tonight.

Given the overnight timing of the storms, confidence is on the
lower side for widespread damaging wind gusts, although can`t
rule out isolated instances of 60 to perhaps 70 mph gusts,
particularly across NW OH where instability and DCAPE will be
highest. Heavy rain and localized flooding is also possible,
given PWATs around 2.0 inches and warm cloud depths exceeding
10kft.

For Tuesday, a cold front will be beginning to sag south across
the Great Lakes, though storm coverage may be more limited due
to large-scale subsidence from the overnight thunderstorm
complex, similar to what occurred this morning. It appears
higher chances for storms may reside further to the south near
the US-30 corridor along remnant outflow boundaries (i.e. pre-
frontal). Any storms that do occur would bring a damaging wind
and hail threat, in addition to heavy rain and localized
flooding.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
The cold front will slowly make its way south through the region
during the day Wednesday, ushering in a refreshing pattern change.
However, the front`s progress will be slowed by the positively
tilted mid/upper trough axis digging across the Upper Midwest and
western Great Lakes. This will cause the boundary to hang near the
southern CWA until Wednesday evening, and pooling low-level moisture
along it combined with synoptic forcing from a 90-100 knot H3 jet
streak rounding the base of the digging trough will lead to some
additional shower and thunderstorm development. Cloud cover and
morning showers should limit the instability, so expect the severe
weather potential to largely be south of the region, but cannot rule
out a strong storm or two with locally heavy rain and gusty winds
given the forcing and lingering juicy airmass. The greatest coverage
of showers and thunderstorm will be from roughly Findlay to
Youngstown.

By Wednesday night, the mid/upper trough axis will swing into the
central Great Lakes, pushing the front south of the region with
broad Canadian high pressure ridging in from the Upper Midwest. This
will bring dry conditions and the beginning of the true airmass
change, setting up mostly sunny and beautiful weather for Thursday
as the large surface high becomes elongated from the heart of the
cornbelt through the Ohio Valley by Thursday night.

Highs in the upper 70s/low 80s Wednesday will cool into the low/mid
70s Thursday with much lower humidity levels. Lows Wednesday night
will fall into the upper 50s/low 60s, with impressive lows of 55 to
60 Thursday night given the clear skies and light winds. Open the
windows!

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
An amplified pattern will remain in place through early next week
characterized by broad mid/upper troughing over the Great Lakes and
Northeast US downstream from strong mid/upper ridging over the
Intermountain West. This will keep the major summer heat out West
while below normal temperatures dominate the eastern US. At the
surface, the broad Canadian high will remain elongated across the
Midwest and Ohio Valley Friday and Saturday, gradually drifting into
the eastern Great Lakes and New England by Sunday and Monday. This
will keep pleasantly cool and dry conditions in place Friday through
the weekend, with very slowly moderating temps as return flow
develops by Sunday and Monday. Uncertainty increases for Monday with
some guidance hinting and warm/moist advection north of an
approaching warm front, so at this time, kept NBM slight chance
PoPs.

Highs will be in the mid/upper 70s Friday warming into the upper
70s/low 80s Saturday and Sunday and low/mid 80s Monday.

&&

.AVIATION /06Z Tuesday THROUGH Saturday/...
An organized line of thunderstorms located along the IN/OH
continues to progress eastward, with recent reports of 60 mph
wind gusts. However, latest radar structure appears to suggest
that it`s weakening as it approaches the I-75 corridor. Did time
out this line of thunderstorms across all TAF sites, with
greater confidence in timing and impact for our western TAF
sites, and much lower confidence for eastern TAF sites. There
is a possibility that this dissipates quickly enough for little
to not thunderstorms to occur at sites along and east of I-77.
Will continue to monitor though. Brief lower ceilings and
visibilities will be possible within thunderstorms.

Thunderstorms should exit the area by 12Z. Additional scattered
showers and thunderstorms should develop later this afternoon
into early tonight. Timing and areal extent of these storms is
very uncertain though, so started with VCSH/VCTS mentions for
now. MVFR ceilings become

Southwest to west winds 10-12 knots with occasional gusts 18-22
knots will diminish this evening to 5-8 knots while becoming south.
Winds gradually turn southwest to west while increasing to 12-15
knots with gusts to 20-22 knots by mid Tuesday morning/early
afternoon. Winds gradually weaken tonight.

Outlook...Non-VFR possible in isolated to scattered showers and
thunderstorms Tuesday afternoon and evening. Non-VFR possible in
patchy fog Tuesday night into Wednesday morning.

&&

.MARINE...
The Small Craft Advisory for the western and central basins will
expire at 20Z since winds and waves have subsided behind the exiting
MCV/wake low. Winds are gradually subsiding in the eastern basin
from Willowick to Ripley, but still seeing enough observed winds in
the 20-25 knot range at buoys and lighthouses to keep the Small
Craft Advisory and Beach Hazards statement going through 00Z. By
tonight, winds will turn SSW and decrease to 5-10 knots for a few
hours, but trends are increasing for another uptick in SW winds of
15-25 knots by Tuesday morning associated with another MCV/wake low.
This will be leftover from a large convective complex that is
expected to develop to the west this evening, so Small Craft
headlines may be needed again Tuesday morning. WSW winds decrease to
10-15 knots Tuesday afternoon and evening, turning NNW Tuesday night
and Wednesday behind a cold front. N winds of 10-15 knots are then
generally expected Wednesday night through Thursday night as
Canadian high pressure builds in from the west, decreasing to 5-10
knots Friday and Saturday.

&&

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

&&

$$

SYNOPSIS...Kahn
NEAR TERM...Kahn/Saunders
SHORT TERM...Garuckas
LONG TERM...Garuckas
AVIATION...Iverson
MARINE...Garuckas