Area Forecast Discussion
Issued by NWS Cleveland, OH

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FXUS61 KCLE 242217
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
617 PM EDT Mon Jul 24 2017

.SYNOPSIS...
A trough extending from low pressure over the eastern Great Lakes
will swing south across the area this evening. High pressure will
build over the central Great Lakes on Tuesday then to the New
England coast on Wednesday. A wave of low pressure will track east
along a cold front over the area on Thursday.

&&

.NEAR TERM /THROUGH TUESDAY NIGHT/...
A trough moving south toward Lake Erie at this time will force
some slightly lower stratocumulus clouds into the forecast area
this evening. Will go with overcast skies in the eastern half of
the forecast area for this evening. Then, as drier air pushes
south into the local area, we should start to see some
improvement in the cloud cover overnight. Latest satellite
imagery currently shows some clearing pushing south across
southern lower Michigan at this time and this supports the
clearing forecast overnight.

Cool air advection will take place and knock temperatures back a
few degrees compared to the last several nights. So it will feel
rather refreshing.

Made some minor updates to extend light rain showers a bit
further west to the Cleveland area through 02z this evening
with the trough.


Previous Discussion...

Satellite imagery shows cloud cover thickening from the north
as a secondary trough extending from low pressure over the
eastern Great Lakes slides south across Lake Erie. As the trough
crosses Lake Erie, weak convergence over the warm waters of the
lake may be sufficient for a few showers to develop, mainly for
points east of Cleveland into NW PA. Anticyclonic flow and
subsidence will reach NW Ohio later this evening with clouds
attempting to scatter out. Meanwhile expecting mostly cloudy
skies to hold across the eastern half of the area and gradually
drift southwest later tonight. Went with a blend of the RAP/NAM
lows for tonight given the expected cloud cover which is
slightly warmer than the MOS guidance.

Clouds will gradually scatter out on Tuesday as we mix out the
shallow moist layer. Clearing across the west half of Lake Erie will
expand inland with time. Some clouds may linger across PA through
the day where highs will be near 70 degrees again. Temperatures will
be warmer in the west with highs near 80. Any lingering cumulus
should clear out Tuesday night. Lows will generally be in the upper
50s with high pressure overhead and light winds.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
Wednesday begins with
high pressure centered over New England extending a ridge back
across Lake Erie. A cold front will extend northeast/southwest
across the western lakes. During the day the ridge weakens
however the airmass across the region will remain dry. Wednesday
night the front will continue to approach the region from the
northwest. By 12Z Thursday the front will be near a line from
the thumb of Michigan to Chicago and is expected to move into
the area during the day. Models a bit different with the
progression of the boundary through the area with the GFS
seemingly drier than the ECMWF. Have shaded the forecast more
toward the ECMWF and will bring likely pops to the region for
Thursday, tapering from west to east Thursday night. Friday will
begin with chance pops east but should dry out quickly with
high pressure building into the region from the northwest.
Seasonal highs to start dropping to a few degrees below normal
by Friday.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
By Friday evening the front is well south of the forecast area and
large area of Canadian high pressure will be centered over the Great
Lakes.  The high will remain anchored over the great lakes providing
dry with temps a little below normal into the weekend.   GFS tracks
low across the Tennessee Valley on Saturday but ECMWF is further
south with the system.  Either way will be a dry forecast. Another
system tracks into the Tennessee Valley on Monday.   Still  appears
far enough south that the forecast should remain dry.

&&

.AVIATION /18Z Monday THROUGH Saturday/...
VFR stratocu deck in place across the region today with just a
few pockets of MVFR ceilings remaining. Expecting ceilings to
lift to VFR all sites by later this afternoon with clouds
starting to scatter out in NW Ohio this evening. NW winds will
be breezy at times this afternoon, mainly at CLE/ERI/CAK/YNG. A
trough will swing south across Lake Erie by 21Z with a few
stray showers possible near ERI. Any showers will be brief.
Ceilings will tend to lower to MVFR at NE Ohio/NW PA sites
tonight as wrap around moisture gets trapped beneath a
strengthening inversion.

OUTLOOK...Non-VFR in thunderstorms with a cold front expected
Thu.

&&

.MARINE...
Winds currently from the northwest at 15 to 20 knots with gusts into
the mid 20s behind a cold front now south of the lake. Waves central
and east are between 4 and 5 feet. Models show another surface
trough dropping across the lake this evening which should sustain
winds into the evening before diminishing. Will continue with
headlines unchanged however if winds remain up an hour or two longer
waves small craft will need to be extended into Tuesday morning
given the northerly direction. Also for this evening will include
the potential for an isolated waterspout east half given favorable
conditions.  Otherwise high pressure will build in for Tuesday
allowing winds and waves to diminish. The next significant weather
maker will be Thursday when a weakening cold front crosses the lake
out of the northwest. Winds with the front are not expected to be a
problem however would expect the need for a small craft advisory by
Friday as north to northeast flow increase to about 15 knots as
building high pressure behind the front tightens the gradient as it
expands east across the lakes and low pressure strengthens in the
lower Ohio valley. Northeast flow will continue through Saturday
although at diminished speeds.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Beach Hazards Statement until 4 AM EDT Tuesday for OHZ009>012-
     089.
PA...Beach Hazards Statement until 4 AM EDT Tuesday for PAZ001.
MARINE...Small Craft Advisory until 4 AM EDT Tuesday for LEZ144>149.

&&

$$
SYNOPSIS...KEC
NEAR TERM...Lombardy
SHORT TERM...TK
LONG TERM...DJB
AVIATION...KEC
MARINE...TK



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