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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCLE 092347
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
747 PM EDT Fri Jun 9 2023

.SYNOPSIS...
High pressure will slide into the Ohio Valley tonight and remain
in place Saturday before exiting off the east coast Saturday
night. This will allow low pressure to develop over the
Mississippi Valley Saturday night and Sunday and slowly move
across the region through Tuesday. High pressure returns by mid
week.

&&

.NEAR TERM /THROUGH SATURDAY NIGHT/...
-- Changed Discussion --
The cu field has dissipated in Ohio with cloud cover in
Pennsylvania slowly eroding from west to east. Have removed any
lingering mention of showers in the far east given continued
dry low level air and only weak echos appearing on radar in
eastern Erie and Crawford counties.

Previous discussion...As of mid afternoon, the old closed low
was still pinwheeling over New England embedded within deep
mid/upper longwave troughing carved out across the eastern half
of the country. A weak vort max and associated cold
front/surface trough pushing south across eastern Lake Erie is
generating a few light showers in Erie and Crawford Counties,
but most of these are not reaching the ground other than
occasional sprinkles due to the dry low-levels. Any leftover
showers will quickly exit this evening as broad surface high
pressure over the Upper Midwest slides into the Ohio Valley
tonight, and the closed low begins to move out of New England.
Much of the smoke/haze has cleared out of the region with nearly
all ASOS sites across northern Ohio and NW PA reporting
unlimited visibilities this afternoon, and expect the rest to
clear out tonight as low-level flow backs more southwesterly.
This will lead to mostly clear skies tonight with lows in the
low/mid 50s. A few places in far NE Ohio and NW PA may still
fall into the upper 40s.

The surface high will remain across the Ohio Valley and
Appalachians Saturday before moving into the Mid Atlantic
Saturday night. At the same time, mid/upper heights will rise
Saturday and Saturday night ahead of a strong shortwave trough
diving into the Upper Midwest. The right entrance region of an
associated 85-90 knot H3 jet will induce weak surface low
pressure over the mid Mississippi Valley Saturday night as the
parent mid/upper trough axis swings toward the western Great
Lakes. This will set up a low and mid-level warm air advection
pattern Saturday and Saturday night with highs warming into the
upper 70s/low 80s Saturday and lows staying in the upper 50s/low
60s Saturday night. Clouds will increase Saturday night as mid-
level moisture advection and isentropic ascent increase, but
slowed down the onset of PoPs due to the very dry antecedent
low-levels causing dew points to be slow to rise out of the 40s.
Only put slight chance PoPs in NW Ohio toward sunrise Sunday
morning.
-- End Changed Discussion --

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
An upper-level trough, turned closed upper low, moves south
towards the Great Lakes region, meandering across the central
Great Lakes through Monday night. At the surface, low pressure
over the mid- Mississippi Valley lifts northeast across the
southern Great Lakes and Ohio Valley Sunday afternoon through
Sunday night. Moisture advection ahead of the low will lead to
modest moisture content available with the right entrance region
of an 80-90 knot upper- level jet and associated upper low
producing substantial forcing for ascent. Model guidance
continues to support an areawide beneficial rainfall for the
region, with this forecast iteration continuing a period of
80-90% PoPs for Sunday afternoon through Monday morning. Timing
of the system is just a touch quicker than previously forecast,
with precip shifting into the Sunday afternoon period, and less
precipitation expected on Monday, though still expecting most of
the rainfall to fall overnight Sunday night. QPF didn`t change
too much with most of the area generally expecting around a half
inch, with ensemble guidance forecasting the lowest QPF for
northwest Ohio (mean of around 0.3") and highest QPF for eastern
Ohio and Northwest Pennsylvania (closer to 0.5-0.75").

By Monday, there is a split in ensemble guidance, though most
members are having the main low become occluded as it continues
eastward away from the Great Lakes, while a secondary low moves
north into southern Ontario and then retrogrades back west to lower
Michigan, becoming vertically stacked with the upper low. Meanwhile,
a dry slot is likely to develop behind the departing primary low,
resulting in gradually decreasing sky cover and lower PoPs for
Monday and Monday night for this forecast period. Below normal
temperatures (by around 5-8 degrees) moves into the region on Monday
and Monday night.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
The upper low, makes eastward progress across the region on Tuesday,
bringing rain showers and anomalously cool temperatures Tuesday and
Tuesday night. Cold temperatures aloft may allow for enough
instability for isolated afternoon thunderstorms to develop on
Tuesday. A weakly forced regime ensues, with a good deal of
uncertainty with the forecast for Wednesday through Friday.
Generally low PoPs and slightly below normal temperatures are
expected.

&&

.AVIATION /00Z Saturday THROUGH Wednesday/...
-- Changed Discussion --
Good aviation conditions with VFR expected through the TAF
cycle as low levels of the atmosphere remain dry. Skies will
tend to clear aside from scattered high clouds overnight and
Saturday. Northwest winds will become light and variable before
developing out of the southwest overnight into Saturday. Winds
on Saturday afternoon will be in the 7-12 knot range. A lake
breeze with wind shift to the west is expected at CLE/ERI in the
15-18Z range.

Outlook...Non-VFR possible with showers and storms Sunday
through Tuesday.
-- End Changed Discussion --

&&

.MARINE...
Weak high pressure slides southeast to the Atlantic coast this
weekend, with weak southwest flow persisting across Lake Erie. Low
pressure over the mid-Mississippi Valley lifts northeast to south of
Lake Erie on Sunday, and then northward across eastern Lake Erie
into southern Ontario Sunday night into Monday. This will result in
rapidly changing cyclonic flow, with winds generally easterly in
advanced of the low Sunday evening, becoming north Sunday night,
then west by Monday. There may be periods of wind approaching or
reaching 20 knots, and thus it`s possible a small craft advisory may
be needed, though there still exists a great deal of uncertainty in
the evolution of the low pressure system and associated winds. West
to southwest winds continue through Tuesday.

&&

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

&&

$$
SYNOPSIS...Garuckas
NEAR TERM...KEC/Garuckas
SHORT TERM...Saunders
LONG TERM...Saunders
AVIATION...KEC
MARINE...Saunders