CLE issues Area Forecast Discussion (AFD) at Sep 5, 8:24 PM EDT115
FXUS61 KCLE 060024
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
824 PM EDT Thu Sep 5 2024
.SYNOPSIS...
High pressure over the northeast states will move offshore tonight
as a cold front in the upper Mississippi Valley approaches the
region. The cold front will move southeast across the region on
Friday. Low pressure and surface troughing will linger through
Saturday over the eastern Great Lakes. High pressure will build into
the region Sunday and remain in place into next week.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
We continue to see isolated shower and thunderstorm potential
across northwest Ohio where moisture is advecting in from the
west. An impressive dewpoint gradient is in place with a
dewpoint of 69 at TOL and 46 at MNN and MFD and 48 at CLE.
Strong theta-e advection is ongoing in the low levels while mid
levels remain warm and dry. With that said, did include some low
pops through the evening in NW Ohio that will gradually expand
east across the lake overnight. Can not rule out a few showers
into north central Ohio but will have to overcome the drier air
before reaching the ground. Coverage of showers will expand with
the cold front on Friday.
Previous discussion...A few showers have developed near TOL
near the eastern edge of a instability gradient that formed due
to the higher dewpoints to the west in IN. Will increase POPs
for this evening in that area.
The main feature during this period is a cold frontal passage that
is expected on Friday. Moisture and instability are expected to be
somewhat limited. Surface dewpoints will rise some ahead of the
boundary but it will take convection to raise surface dewpoints well
into the 60s which may happen at frontal passage time. CAPE values
are expected to briefly climb to over a 1000 J/KG with the onset of
convection with prefrontal wind shear of 25-30 knots. A band of
convection will likely develop near noon as the front reaches the I-
71 corridor. The front will likely clear the CWA by 23Z. The highest
chance of severe weather is east of I-71 from 18-22Z with wind
damage being the main threat but confidence is low.
The HREF indicates that QPF could reach 1-1.5" over extreme
northeast Ohio north of I-80 and east of I-71 and east into
northwest PA. These amounts are possible but may be isolated.
The convection will continue into the early evening in the eastern
half of the CWA before diminishing after midnight. Mainly drier
conditions are expected Friday night over the western half of the
CWA.
As the front moves southeast, cooler and less humid air will move
into the region later Friday night.
&&
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
A much cooler air mass will settle over the region for the weekend
as north/northwest flow develops in response to an upper trough
meandering east across the eastern CONUS. There will be quite a bit
of lake-induced instability as 850mb temperatures plummet to 1 to 4C
Saturday so scattered lake-enhanced showers and perhaps isolated
thunderstorms will likely persist across NE OH and NW PA through
Saturday afternoon. Showers should gradually dissipate by Saturday
night as dry air filters in with the arrival of a surface high and
expect dry weather with scattered lake effect clouds for the second
half of the short term period.
Below normal temperatures return for the weekend with highs in the
60s anticipated for Saturday and the 60s and lower 70s (NW OH)
Sunday. The cooling trend will be apparent in overnight lows as
well; expect minimum temps in the low to mid 40s Saturday night and
mid to upper 40s for Sunday night. Will need to keep a close eye on
temperature, wind, and sky cover for Saturday night; conditions may
end up being favorable for patchy frost in far southern zones where
minds may be a bit lighter.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
Surface high pressure with a ridge aloft will anchor over the region
for the long term period. As a result, the weather pattern will turn
tranquil with dry weather favored through the majority of the week.
Warm air advection will allow temperatures to increase throughout
the period with highs in the 70s and lower 80s Monday giving way to
highs well into the 80s by Wednesday and Thursday. Overnight lows
will gradually increase as well, but generally expect minimum temps
in the 50s through most of the period.
&&
.AVIATION /00Z Friday THROUGH Tuesday/...
VFR conditions are in place across the area with isolated
showers possible at TOL and to a lesser extent FDY overnight.
We will start to see a gradual expansion of showers east across
Lake Erie late tonight but really think it will take until a
cold front moves in from the northwest to see a better expansion
of showers. The cold front will reach TOL towards 12Z, CLE and
MFD towards 19Z and CAK/YNG towards 20Z. Tried to time showers
into the terminals along the front with vicinity thunder in for
a couple hours at eastern sites where the front will arrive
during the afternoon. Visibilites may be reduced to MVFR in
showers and locally down to IFR in thunderstorms but confidence
was not high enough yet to include a lot of these restrictions.
Ceilings will also trend down into the MVFR range behind the
cold front.
Winds overnight will tend to be south or southeast, veering to
southwest ahead of the front and northwest/north behind the
front. Winds will tend to be 8-12 knots ahead of the front and
then 10-14 knots behind the front with gusts to 22 knots.
Outlook...Non-VFR in Periodic showers into early Saturday in
the snowbelt. Scattered showers and pockets of MVFR linger in NE
Ohio and NW Pennsylvania into Sunday morning.
&&
.MARINE...
South/southwest winds increase to 10 to 20 knots tonight as warm air
advection deepens ahead of an approaching cold front. As of now, the
highest winds and waves will be focused offshore so do not
anticipate any headlines with the period of offshore flow. Winds
will diminish a bit by daybreak Friday before shifting to the
northwest and increasing to 15 to 20 knots behind the cold front by
Friday evening. Northwest winds 15 to 20 knots will continue well
into the weekend so Small Craft Advisories will likely stretch from
Friday night through at least Sunday afternoon. In addition to the
gusty winds, the cooler air mass over the warm lake will result in
an increase risk of waterspouts over the weekend, best chance with
the passage of the cold front Friday and with the strongest cold air
advection Saturday.
Winds become southwesterly and diminish to about 10 to 15 knots by
Monday before diminishing to 10 knots or less Tuesday.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
NY...None.
MARINE...None.
&&
$$
SYNOPSIS...LaPlante
NEAR TERM...KEC/LaPlante
SHORT TERM...Maines
LONG TERM...Maines
AVIATION...KEC
MARINE...Maines
Source:
CLE issues Area Forecast Discussion (AFD) at Sep 5, 8:24 PM EDT---------------
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