383
FXUS61 KCLE 161413
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
1013 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 WEDNESDAY/...

10:10 AM EDT Update...
A prominent cyclonic MCV centered over southern ON, near the
north-central Lake Erie shore, is expected to move ENE`ward to
far-northern NY, just east of Lake Ontario, by this early
evening. Simultaneously, the attendant mesoscale surface low is
expected to track generally E`ward from western Lake Ontario to
far-northern NY. Moist isentropic ascent associated with the
MCV`s warm conveyor belt may release enough instability,
including elevated CAPE, to trigger isolated showers and
thunderstorms over/near central and eastern Lake Erie through
this early afternoon. In addition, SW`erly to NW`erly surface
winds gusting up to 25 to 35 knots and associated with the
mesoscale surface low`s cyclonic circulation/diurnal convective
mixing of the boundary layer tapping into stronger flow aloft
are forecast to ease by this early afternoon as the MSLP
gradient relaxes in the wake of the low. Stabilizing subsidence
behind the MCV is expected to promote primarily fair weather
through sunset this evening. However, will have to watch
expected lake breeze development within several miles of Lake
Erie this afternoon through early evening. The lake breeze front
may trigger a few showers/thunderstorms amidst weak to moderate
boundary layer CAPE, sizable DCAPE, and moderate effective bulk
shear. Thus, a few severe thunderstorms with damaging
convective gusts are possible along and downstream (i.e.
generally east) of this expected lake breeze front. Will also
have to monitor our northern OH counties, south of roughly U.S.
Route 30, where model guidance appears to suggest low-level
convergence/moist ascent along mesoscale fronts related to
differential diurnal heating may trigger a few
showers/thunderstorms amidst the aforementioned
thermodynamic/kinematic environment favorable for strong to
damaging convective gusts. Will continue to monitor trends in
obs and model guidance, including CAM`s, closely. Made minor
adjustments to POP`s/QPF/sensible WX grids per aforementioned
trends. Rest of forecast remains valid. Please see discussion
below for further details.

Previous Discussion...
A line of storms west of I-77 continued to move across the
area, producing very isolated strong wind gusts. This activity
should be out of the area by 12Z. Meanwhile, a wake low moving
to our north has been responsible for locally strong winds west
of I-71 this morning, with observed gusts of 35kts at KTOL and
33 kts at KFDY. Should see this activity spread east and may see
brief 1-3 hour period of gusty winds before winds gradually
diminish through the day today.

Additional isolated to scattered showers and thunderstorms may
develop this afternoon/evening, though trends do not look very
favorable for severe weather despite most model guidance
forecasting moderate instability (1500-2000 J/kg MUCAPE) paired
with marginal deep layer shear (20-25kts). Subsidence in the
wake of an MCV will likely prevent too many robust updrafts in
our forecast area this afternoon. Additionally, most CAM
modeled reflectivity have an MCS (and possibly another MCV)
developing over Illinois and moving east to the south of our
forecast area by this evening into tonight. If an MCV does
develop to our south, this could potentially be a focus for
additional shower/thunderstorm develop this evening into
tonight. For now, most of the area in a marginal risk for severe
weather (level 1/5) but it`s a pretty low confidence forecast
at this point. Strong winds gusts would be the most likely
weather hazard.

By tomorrow a cold front moves in from the northwest. Most
models have a broken line of showers and thunderstorms
developing along this front during the afternoon hours. There
will be much less instability (~750-1000 J/kg MUCAPE) but
greater deep-layer shear (30-50 kts, depending on the model).
The 06Z HRRR/NAM Nest both have weak updraft helicity tracks but
it seems unlikely for this to happen. Even so, this will be
worth monitoring.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
If you`re tired of the warm and humid weather with low-
predictability convection then this portion of the forecast is for
you. Wednesday`s cold front may still be exiting during the evening
so do linger low chances for showers across our southeast the first
part of Wednesday night. Otherwise, a seasonably deep longwave
trough will be settling into the Great Lakes Wednesday night into
Thursday before shifting east-northeast into Quebec and New England
to end the work week. We may actually get lake effect clouds and a
few sprinkles Thursday morning as the trough digs in amid strong
cold air advection over the lake. Otherwise, strong high pressure
builds in Thursday night and persists through the end of the work-
week bringing mainly clear and refreshingly cooler conditions. Look
for highs in the low to mid 70s on Thursday and in the mid to upper
70s on Friday with dew points falling safely into the 50s by
Thursday afternoon. Overnight lows will likely still be in the low
to mid 60s Wednesday night but should get into the 50s outside of
the immediate lakeshore and denser urban corridors Thursday and
Friday nights. As the prior discussion said, open those windows.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
Strong high pressure remains in control through Saturday night as we
remain beneath upper-level confluence on the backside of the
departing longwave trough. High pressure slowly weakens Sunday into
Monday as the trough to our northeast continues to depart, with the
next modest trough deepening across the Mississippi Valley by the
beginning of next week, encouraging broad and light south-
southwesterly flow over our region. High confidence in dry weather
through Saturday night. The weakening high pressure and some
moisture return on Sunday make it a bit harder to completely rule
out any chance for an increase in clouds and perhaps a stray shower
but odds in any one spot are still under 20%, precluding a forecast
mention. No major systems on Monday but gradual return flow
continues, so do begin including some 20% POPs (which does not
garner a forecast mention in our text products that far in the
future). Overall, very low impact weather for this period. Highs
will return to the low to mid 80s through the weekend with overnight
lows ranging from the upper 50s to mid 60s Saturday and Sunday
nights, with low to upper 60s in the forecast for Monday night.

&&

.AVIATION /12Z Tuesday THROUGH Saturday/...
Brief MVFR ceilings may move across the area this morning, with
areawide VFR expected this afternoon/evening. Isolated to
scattered showers and thunderstorms are possible this evening
into tonight. For now, went with VCSH and removed any mention of
thunderstorms, as confidence in the occurrence of thunder has
decreased from previous TAF issuance. Some MVFR ceilings may
develop late tonight, especially across the southern part of the
forecast area (e.g. at TAF sites such as KMFD, KCAK, and KYNG).

Winds briefly increase to 10-15 knots this morning with gusts of
up to 20-25 knots (perhaps even very brief 30 knot gusts). These
winds should diminish by the afternoon, remaining under 10 knots
through the rest of the TAF period.

Outlook...Non-VFR possible with isolated showers and
thunderstorms on Wednesday.

&&

.MARINE...
Similar to yesterday an MCV (small low pressure generated by
thunderstorms) is currently over southeastern Michigan and will move
over or just north of Lake Erie this morning through early this
afternoon. Several hi-res models depict enhanced west-southwest
winds of 20 to perhaps briefly 30 knots moving west-east across the
lake on the south side of the MCV, and are already seeing that
across Northwest OH and the waters off of Toledo. Given that, have
issued a short-fused Small Craft Advisory until noon west of
Vermilion and 4 PM farther east. Otherwise, mainly light winds are
expected on the lake over the next several days. In decent cool air
advection northerly winds will increase to around 15 knots late
Wednesday night into early Thursday which will build some 2-4
footers in the nearshore waters. Will closely monitor that wind
forecast as an uptrend could result in a Small Craft Advisory,
though the current wind/wave forecast is below criteria.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Beach Hazards Statement until 4 PM EDT this afternoon for
     OHZ011-012-089.
PA...Beach Hazards Statement until 4 PM EDT this afternoon for
     PAZ001.
NY...None.
MARINE...Small Craft Advisory until noon EDT today for LEZ142>144.
     Small Craft Advisory until 4 PM EDT this afternoon for
     LEZ145>149.

&&

$$

SYNOPSIS...Saunders
NEAR TERM...Jaszka/Saunders
SHORT TERM...Sullivan
LONG TERM...Sullivan
AVIATION...Saunders
MARINE...Sullivan