Area Forecast Discussion
Issued by NWS Cleveland, OH

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FXUS61 KCLE 191317

Area Forecast Discussion
National Weather Service Cleveland OH
917 AM EDT Sat Aug 19 2017

Weak low pressure associated with a disturbance aloft will drop
across the lower Great Lakes and Ohio Valley today. High
pressure will build across the Ohio Valley and eastern Great
Lakes Sunday, then move east of the area on Monday. The next low
will move northeast across the Great Lakes Tuesday and take a
cold front across the local area Tuesday night.


Update...Updated sky cover lowering clouds west and increasing
clouds central and east to start. Also updated pops increasing
to likely invof and east of showers and thunderstorms moving
through the area as well as dropping morning pops west where
skies were partly cloudy. Still like afternoon pops highest
southeast counties. Sharpening upper trough swinging through the
area and developing diffuse front/trough which will increase
afternoon convergence southeast will interact with increasing
instabilities moving into the area this afternoon. Mid level
drying could also interact with storms causing strong
gusts/downbursts with convection.

Previous discussion...Fairly sharp shortwave/upper trough to
cross the area today. The surface reflection is rather weak
though. Mid/high clouds already beginning to overspread the area
before dawn. System will be working with limited moisture so
expect shower/thunderstorm coverage to be scattered at best.
Latest guidance brings the small cluster of storms from northern
IN into northwest OH followed by a diurnal lull and then a
flare up again along or just east of the I-71 corridor. Marginal
instability with daytime heating and decent lapse rates with
the trough could produce a few feisty storms but by the time
that all comes together activity should be across eastern
counties and it would not be much longer before it would be out
of the county warning area. Overall this is a quick system and
any one place has just a few hours for the threat for
precipitation. Highs a little on either side of 80 degrees.

Clearing and light/variable winds in the wake of today`s
disturbance for tonight. This may introduce a patchy fog for
early Sunday morning. With high pressure building overhead,
Sunday will be quiet with partly cloudy afternoon skies and
seasonable temperatures.


High pressure will drift across the region Sunday night with it east
of the area on Monday. This will allow southerly winds to develop
and begin the return flow of moisture. Warm advection and some weak
convergence along a lake boundary may be enough to cause an
isolated thunderstorm across inland NW PA and maybe over NW OH. For
the most part expect to see some afternoon cumulus with highs in the
mid to upper 80s. Thunderstorm chances will increase after midnight
Monday night but the best chances arrive Tuesday afternoon into the
evening as the cold front moves across the region. Thunderstorms
will end from west to east overnight with the cold front passage.
Cooler Tuesday with the added cloud cover and thunderstorms but highs
will still reach the lower to mid 80s. A gradual decrease in
humidity Tuesday night with lows in the lower to mid 60s.


There could be some lingering showers across NE OH/NW PA into
Wednesday afternoon. High pressure will begin to increase its
influence at the surface Wednesday night into Thursday. However
another upper level trough will be approaching. This trough will
cross the area on Thursday but with low level moisture in question
we will not place more than 20 percent POP`s in the forecast. By
Friday high pressure should take control of the area.

Cooler temperatures area expected through the long term forecast
with highs in the lower to mid 70s. Lows most locations will dip
into the 50s. A few upper 40s may occur across inland NW PA by
Friday night.


.AVIATION /12Z Saturday THROUGH Wednesday/...
A few showers/thunderstorms to start off the morning will be on
the doorstep or in the vicinity of CLE/MFD as of 12Z. It is
expected to weaken beyond that. While there is only a weak
surface reflection with the system moving across the Ohio Valley
today, the upper trough is a bit potent and will spark more
isolated to scattered showers/thunderstorms this afternoon. Have
maintained best coverage across YNG/CAK with tempo mentions.
Brief MVFR/IFR possible with any storm. Light south winds will
shift to the west for this afternoon before backing and becoming
light south again late tonight. BR/FG a possibility late

OUTLOOK...Non-VFR possible eastern OH/inland nw PA Sunday
morning. Non-VFR possible in scattered showers/tstms on


A reinforcing surge of cooler air will move across the area this
afternoon with an upper level trough. Westerly winds will persist
through the day and may become strong enough to produce 2 to 4 foot
waves from Willowick to Ripley. There is a possibility of waves
building to 3 to 5 feet for a few hours mid afternoon into the
evening. Later shifts will need to watch this potential as winds
shift around to the northwest this afternoon.

High pressure will then build across Lake Erie tonight into Sunday.
This high will shift east of the region on Monday as the next area
of low pressure moves into the Western Great Lakes by Tuesday.
Southwesterly winds will increase ahead of a cold front on Tuesday.
Winds will likely be the strongest in the wake of the cold front
Tuesday night into Wednesday with strong cold advection anticipated.
This should be enough to require small craft advisories.




NEAR TERM...TK/Oudeman
LONG TERM...Mullen
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