Area Forecast Discussion
Issued by NWS Cleveland, OH

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FXUS61 KCLE 151035
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
635 AM EDT Tue Aug 15 2017

.SYNOPSIS...
A cold front will push southeast across the region today, settling
just north of the Ohio River late tonight into Wednesday morning.
The front will lift north through the region Wednesday night into
Thursday as low pressure develops over the Plains and tracks into
the Great Lakes region. The low will bring a cold front through the
region Friday, with high pressure building across the region behind
the front this weekend.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
No changes to the forecast with the early morning update.
Watching showers/storms across southern lower MI, but currently
thinking this activity will translate more eastward, skirting
north of the forecast area, with current pops on track for NW
OH.

Original discussion...
Upper shortwave noted on W/V imagery early this morning near
Lake Michigan and associated surface low/boundary will work
eastward across lower MI towards Lake Erie through the morning
hours. Some scattered showers/iso thunder on radar near the
surface reflection in SW lower MI warrants a slow increase to
slight chance pops in NW OH around 12Z. As increased 925-700mb
flow translates eastward with the quick moving shortwave, any
convection should diminish a bit mid/late morning.

Uptick in convective activity possible this afternoon as the surface
reflection becomes more diffuse as the remnant cold front/trough and
aggregate lake breeze settle south into the forecast area. Modest
destabilization ahead of the boundary, up to 1000 j/kg, will promote
convection along and south of the boundary through the afternoon.
Coverage should be rather isolated/scattered, as depicted by the
latest run of several hi-res CAMS, with a bit of weak capping around
600 mb and rather dry low levels outside of the 850 mb layer.
Therefore, will maintain slight chance pops through the afternoon
for much of the area, with a quick downward trend near sunset with
the loss of daytime heating, although a stray shower/storm could
linger into the overnight.

Southerly flow will ramp up ahead of developing Plains low pressure
on Wednesday. Most of the area should remain dry through the daytime
hours, and have removed the slight chance pops given meager
instability, dry air and lack of forcing. Pops increase late in the
evening into the overnight. No major changes to temps today or
Wednesday, with highs in the low/mid 80s for most locations.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
High pressure at the surface and aloft will take a while to move
east but the low level jet will begin to push into the area
Wednesday night. The best chance to see any showers/storms would be
across NW OH after midnight.

By Thursday, the main short wave will be crossing the northern lakes
with a trailing short wave crossing the western Great Lakes. The low
level jet and a broad area of warm advection will spread across the
area, likely resulting in a fair amount of clouds and a scattering
of showers and thunderstorms. CAPE is progged to slowly increase
above 2000 with the heating of the day but not much of a trigger
until the short wave and front approach later in the day and
Thursday night. Will have 50-70 pops across much of the area
Thursday into Thursday night. Temperatures are tricky depending on
the amount of clouds and showers but there will likely be enough dry
time during the day for high temperatures to sneak into the mid 80s.
Dew points should be well in the 60s.

The front may take until sometime Friday to cross the area,
especially for the eastern counties. The model soundings show drying
aloft and increasing subsidence as the short wave lifts out. Will
keep a small chance of showers in the forecast, mainly across NE OH
and NW PA.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
Another progressive short wave is progged to cross the eastern Great
Lakes on Saturday. The air mass will be drier and relatively stable
and convection may occur primarily to the south where the air mass
is more unstable. Nonetheless, we could end up with clouds and at
least a small chance for a shower or thunderstorm.

High pressure should build in by Sunday. The models are not as cool
with the forecast air mass as they were yesterday. High temperatures
by Sunday and Monday will probably end up near normal.

&&

.AVIATION /12Z Tuesday THROUGH Saturday/...
Cold front will sink southeast across the region today, with
mainly VFR conditions expected. Any MVFR BR will lift quickly
this morning at the terminals. The cold front will bring
isolated to scattered thunderstorms across northern Ohio.
Coverage is expected to be fairly scattered, which precludes TAF
mention at this point. Winds will pick up out of the
west/southwest this afternoon, veering more northerly as the
front moves through the area.

OUTLOOK...Patchy BR possible each morning. Areas of Non-VFR possible
Wednesday evening through Thursday with scattered storms.

&&

.MARINE...
Light south winds on Lake Erie will become southwest ahead of a
weakening cold front today. The front will sag across the lake this
afternoon although the gradient will be so weak that the lake breeze
will cause wind shifts earlier in many locations.

The northeast wind will pick up behind the front tonight and
Wednesday. Not expecting enough of a push for anything significant
but the prolonged northeast fetch could cause the lake to get a
little choppy on Wednesday.

The next cold front is due Friday morning. The wind will veer from
northeast to south on Thursday and not expecting speeds to increase
until Thursday night. Winds will shift to northwest behind the front
on Friday and a small craft advisory may be needed Friday into
Friday night. High pressure will build in rather quickly this
weekend. The west wind may continue to make the east half of the
lake choppy on Saturday but the lake should quiet down as the
weekend goes on.

&&

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

&&

$$
SYNOPSIS...Greenawalt
NEAR TERM...Greenawalt
SHORT TERM...Kosarik
LONG TERM...Kosarik
AVIATION...Greenawalt
MARINE...Kosarik



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