Area Forecast Discussion
Issued by NWS Cleveland, OH

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FXUS61 KCLE 202238
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
638 PM EDT Thu Jul 20 2017

.SYNOPSIS...
Diffuse boundary will push south of the area tonight then lift NE
across the area again late Friday.   Low Pressure will track along
the boundary across the area this weekend.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
Generally fair weather is expected tonight across the region as
forcing for convective initiation is difficult to discern.
Convection to the southeast continues to move away with just
scattered cu and high clouds across the region. Isolated light
showers over the western part of the CWA have diminished
recently. Instability is modest with values <1500 J/kg which
continues to drop. Will lower pops to slight chance over the
southern counties for the next few hours.

Front should be SW of the forecast area on Friday providing a
dry forecast. More convection on tap for the weekend. The front
lifts into area again Friday night and stalls, with low pressure
tracking into Central lakes by daybreak Saturday.


&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/...
Remnant convection is expected to be moving southeast into the
area along the instability gradient on Saturday morning.
Although the frontal boundary will be attempting to lift north
towards Lake Erie, incoming activity will likely align along
this boundary and tend to move southeast. The difficult
component is figuring out where the boundary gets held up at or
lift north with time. Degree of cloud cover and intensity of the
morning activity will play a role in additional development
during the afternoon/evening. If we see enough clearing, would
expect moderate destabilization to occur near and south of the
boundary with strong to severe storms possible during the
afternoon as the boundary tries to push north. Deep layer shear
should be sufficient for organized convection during the
afternoon with shortwave energy moving through the flow aloft.
Backed surface flow is expected in the vicinity of the front
with rotating storms possible.

Periods of heavy rain will be a concern over the weekend from late
Friday night through late Saturday night. Depending on the nature of
the convection as it arrives Saturday morning, training storms will
be possible as they move along the frontal boundary. The same will
be true both Saturday afternoon and again Saturday night. The
airmass will be very moist with PW values near 2 inches producing
efficient rainfall. QPF of 1-2" is likely across most of the
area over the weekend but locally higher amounts are expected.

Drier air will arrive from the west on Sunday. A chance of thunder
storms will remain but will be more scattered by Sunday afternoon
and night as a front arrives from the north. With residual low level
moisture, will continue with partly cloudy skies and a low chance of
showers in the south and east on Monday.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
As the daytime heating starts to subside, any leftover instability
shra/tsra should be ending around 00z Mon eve. High pressure over
the area should then produce dry conditions thru Wed night before a
cold front sags south near Lake Erie by late thu to bring the next
chc for shra/tsra.

Temps will start out a little below normal for Tue then moderate to
near normal by Thu along with increasing dewpoints.

&&

.AVIATION /18Z Thursday THROUGH Tuesday/...
For today expect an increasing chance of thunderstorms through
the day as a cold front drops into the area and becomes the
focus for low level forcing and convective development. High
pressure will build in from the north overnight forcing any
remaining convection south and southwest through the evening and
early overnight hours as drier air moves in from the north.
Expect VFR today outside of thunderstorms. Overnight lingering
convection south and southwest could continue restrictions.
Toward morning Friday non VFR possible due to morning fog.

OUTLOOK...Non-VFR possible Friday night through Sunday in early
morning fog/mist or scattered thunderstorms.

&&

.MARINE...
A weak frontal boundary will settle south across Lake Erie tonight
with winds shifting to the north by Friday. The wind field is
expected to be light as high pressure builds over the lake and will
become more onshore by afternoon.

Winds on the lake over the weekend will be highly dependent on
thunderstorm activity as multiple rounds of thunderstorms may cross
the lake. Winds are expected to develop out of the southeast
Saturday morning as the frontal boundary pushes back north to near
the Lake. In the absence of significant thunderstorms, winds are
expected out of the southwest. Low pressure will track along this
boundary and eventually shift around to the north late Sunday as the
front pushes south again. High pressure will expand over the Great
Lakes early next week brining improving marine conditions.

&&

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

&&

$$
SYNOPSIS...DJB
NEAR TERM...LaPlante
SHORT TERM...DJB/KEC
LONG TERM...Adams
AVIATION...DJB
MARINE...TK



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