Area Forecast Discussion
Issued by NWS Cleveland, OH

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115
FXUS61 KCLE 172002
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
402 PM EDT Thu Aug 17 2017

.SYNOPSIS...
Low pressure will track northeast across the Upper Great Lakes
tonight with a cold front moving east across the area. The low will
continue northeast into Canada with high pressure expanding up the
Ohio Valley Friday night into early Saturday. A secondary upper
trough will swing across the Great Lakes region on Saturday.

&&

.NEAR TERM /THROUGH FRIDAY NIGHT/...
Vigorous convection has not been able to get established this
afternoon along the line in northern Ohio. The convection has
outpaced the better height falls to the west and convective
debris cloud has outpaced the line and had a limiting effect on
destabilization. We will continue to monitor for any stronger
cells that develop as we head into peak heating, but the severe
weather threat appears to be isolated in nature. Rain will
continues to move northeast and most areas will see some showers
with just scattered thunderstorms as this line continues to the
east.

Much drier air aloft spread in from the west overnight as the mid-
level dryslot wraps around the trough. High dewpoints will make
conditions feel humid overnight and some areas of stratus could
develop as the high cloud clears out aloft. Patchy fog also possible
but not expecting it to get too bad with southwest winds of 5 to 10
mph.

Low pressure will continue to track northeast into Canada on Friday
with breezy west southwest winds gusting to around 20 mph. Trimmed
back any chance of rain on Friday to just a low chance in NW PA.
Expecting partly to mostly cloudy skies as a healthy cu field
develops with daytime heating. High pressure will expand up the Ohio
Valley Friday night. Clouds will begin to increase late ahead of
the next trough approaching from the west.
&&

.SHORT TERM /SATURDAY THROUGH MONDAY/...
A trough is progged to move east across the cwa on Sat. Upper
support looks good but surface moisture and focusing is weaker so
will keep pops in chc category. A few leftover shra could still be
in NW PA Sat night, otherwise high pressure spreads in from the west
and should dominate thru Mon and keep conditions dry. Temps should
start out near to a little below normal Sat then warm to be above
normal by Mon.
&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
A fast moving upper level trough will push east across the eastern
United States during the extended periods Monday night through
Wednesday.  This will cause a fast moving surface low pressure to
race across the Great Lakes region during the same time period.
Models are suggesting the low pressure system will begin to spread
some moisture into the local area Monday night into Tuesday with a
chance for showers and thunderstorms along the cold front.  Once
storm system moves east of the area, a large area of high pressure
will begin to nose southeast toward the local area for the latter
half of the forecast period.  Warm air advection will take place in
advance of the low pressure but after frontal passage, we should see
some cold air advection.  Possibility exists for some lake effect or
better yet lake enhance rain showers after frontal passage across
the northeast.  Would not be surprised with cold air sliding south
across the area that we see some waterspouts and cold air funnels
during the latter half of the week.

&&

.AVIATION /18Z Thursday THROUGH Tuesday/...
A broken line of showers and thunderstorms moving into NW Ohio
will continue to spread northeastward ahead of a low pressure
system moving towards the upper Great Lakes. Tried to time a 2-3
hour window of thunderstorms into most terminals this
afternoon. Conditions ahead of this line are mostly VFR.
Thunderstorms will produce very heavy rainfall and brief IFR
conditions if they pass over a terminal. Isolated wind gusts in
excess of 40 knots are also possible if thunderstorms intensify.
Otherwise southwest winds will be breezy with gusts up to 25
knots outside of thunderstorms through 23Z

A cold front will move east across the area this evening with
much drier air arriving behind it. Clouds expected to scatter
out although some MVFR stratus will attempt to develop across NE
Ohio overnight. A broken cu field of 2500-3500 feet will expand
across all areas on Friday. Southwest to westerly winds will be
breezy on Friday with gusts 25 knots.

OUTLOOK...Areas of Non-VFR possible in showers Saturday.

&&

.MARINE...
The cold front moving across the lake tonight will gradually veer
winds from SW to West thru Fri afternoon with speeds increasing to
15 to 25 knots eventually bringing 4 foot or better waves into the
nearshore Fri aftn. Winds will slowly settle down into Sat night
while wavering back and forth as a trough crosses the lake Sat. High
pressure will tend to dominate Sun into Mon with winds eventually
turning out of the SW by Tue and increasing to 10 to 20 knots ahead
of the next cold front.

&&

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

&&

$$
SYNOPSIS...KEC
NEAR TERM...KEC
SHORT TERM...Adams
LONG TERM...Lombardy
AVIATION...KEC
MARINE...Adams



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