Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Cleveland Ohio
832 PM EDT Sat Aug 29 2015
weak surface low pressure over the middle Mississippi Valley will
dissipate as a weak tough aloft slides east across the area late
tonight. Bermuda high pressure along the East Coast will remain
nearly stationary and build through much of the new week.
Near term /until 6 am Sunday morning/...
update...boosted probability of precipitation to likely northestern Ohio and northwestern PA for the
evening. No other changes at this time.
Original...the weakening short wave aloft will continue sliding
east over the top of the ridge overnight and Sunday. Will have to
deal with a few showers that have bubbled up from the afternoon
and will have a slight chance of showers out of The Gate this
evening except for around Erie PA.
Decent upper divergence is prognosticated aloft in the left entrance region
of the jet tonight. Pretty feeble low level jet though...prognosticated to
drop to 15-20 knots tonight over the local area. These weak warm
advection positively tilted systems tend to do better at night...and
do anticipate some expansion of the showers across northwest and
north central Ohio. The activity will spread across northeast Ohio
and northwest PA later. Not a big risk of thunder given the
relatively weak upward motion and warm temperatures aloft but cannot rule
it out and will keep it in the forecast across Northwest Ohio to
about the I-71 corridor.
Lows from the middle 60s across Northwest Ohio where it will be
cloudier and dew points have come up...to lower 60s/around 60 extreme
NE Ohio/northwest PA.
Short term /6 am Sunday morning through Tuesday night/...
Sunday will likely feature a diminishing of the early morning
showers and few new showers/storms bubbling up. Probably not a lot
of duration but 30-50 pop for most areas. Temperatures may not get as
warm as they could given the amount of cloudiness. Highs mostly in
the lower 80s with some middle 80s where there is more sunshine.
The ridge aloft is prognosticated to rebound on Monday with subsidence
behind the exiting trough. The ridge begins to look like a classic
Bermuda high this week. Despite the heat and increasing
dew points...afternoon convection tends to be minimal this time of
year given the ridging aloft...lower sun angle and lack of a trigger
so not real excited about much in the way of thunderstorms. Cannot
rule out a few storms with the best chance over the Appalachians and
to the west where there is better low level moisture and slightly
less ridging. Some of the activity to the west may spill over into
northwest and north central Ohio. Highs generally in the middle 80s
with upper 80s in some of the warmer spots. Lows in the 60s to near
70. Summer hangs on.
Long term /Wednesday through Saturday/...
the models generally still keep a large upper ridge over the
region during the period but now there is some indication of a
weak backdoor system dropping in from the north around the
Thursday time frame. Will show slight chance probability of precipitation for this
possibility...otherwise will keep slight or less chance probability of precipitation going
for mainly afternoon and evening isolated convection. Temperatures should
stay above normal.
Aviation /00z Sunday through Thursday/...
scattered showers are moving through the area ahead of a
trough approaching from the west. Thunder has been very isolated
thus far so just carried showers at most sites...except at tol/fdy
where it seemed chances were slightly better as area of thunder in
western Indiana approaches after 03z. Conditions will generally be
VFR through 06z except brief MVFR visibilities in the heavier
Dewpoints will continue to come up overnight and visibilities may
drop into the MVFR range after 08z. Expect visibilities to improve by
14z with scattered showers and possibly thunderstorms increasing
with daytime heating...mainly at eastern sites. Winds will be light
and somewhat variable overnight...developing out of the south on
Outlook...non VFR possible into Monday with isolated showers and
thunderstorms. Areas of non VFR in morning fog.
the pattern will show little change with high pressure in
control producing light mainly S to SW winds. There is some
possibility that a weak backdoor cold front could drop down around
the lake by Thursday that would turn winds to the NE but even if this
does occur winds still look to stay 10 knots or less.