CLE issues Area Forecast Discussion (AFD) at Nov 11, 12:55 AM EST619
FXUS61 KCLE 110555
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
1255 AM EST Mon Nov 11 2024
.SYNOPSIS...
A cold front will sweep eastward through the local area this
evening through the wee hours of Monday morning and a secondary
cold front will sweep southeastward across our region Monday
afternoon through early evening. Behind the second cold front, a
ridge builds gradually from the Upper Midwest through the
middle of this week.
&&
.NEAR TERM /THROUGH TODAY/...
9:40 PM Update:
A broken line of low-topped convection has developed right along
the cold front from central Lake Erie southwest down the I-71
corridor. This will continue to sweep east through the remainder
of the evening as the front quickly moves through the rest of
our area. The potential for "funny business" with this strongly
forced, strongly sheared convection is low but not quite zero. A
small amount of low-level instability (0-3km CAPE of 50-100
J/KG) has developed and the convection is surface-based, with
0-3km shear values of 50-60kt. There was a bit of severe weather
in Michigan earlier this evening, including a couple of likely
brief/weak tornadoes based on radar-indicated tornadic debris
signatures. The environment in our local area isn't much
different from what was in place over Michigan, though we are a
bit more displaced from the stronger forcing and the instability
is a bit shallower this far south. Thus far the activity has
behaved, but if any line segments are able to become slightly
more north-south oriented and take greater advantage of the very
strong 0-3km shear, concern could briefly/locally increase. The
main concern if anything turned severe would be very isolated
straight-line wind damage or a brief/weak QLCS tornado.
Otherwise, the prior forecast is on track and only minor
changes were needed with this update.
Previous Discussion:
Aloft, SW'erly flow veers to W'erly over our entire CWA by
daybreak Monday as a potent trough traverses our region
generally from west to east this evening through the wee hours
of Monday morning and is followed by a weak/subtle shortwave
ridge building from the north-central United States and
vicinity. At the surface, a trough lingers over our region as a
vertically-stacked and occluded low moves from the northwestern
Great Lakes to southern QC, which will allow a cold front to
sweep E'ward through our region between about 7 PM EST this
evening and the wee hours of Monday morning. Periods of rain,
heavy at times, are expected due to low-level convergence/ascent
along the cold front amidst sufficient moisture and weak
potential instability in the lowest 1 km AGL, and moist
isentropic ascent preceding the trough axis aloft. Net low-level
CAA behind the front will contribute to lows reaching the 40's
to lower 50's around daybreak Monday morning. In addition, odds
favor fair weather behind the cold front as stabilizing
subsidence accompanies the aforementioned shortwave ridge.
However, a somewhat moist W'erly mean low-level flow amidst 850
mb temperatures falling to near 2C over ~14C Lake Erie may
allow isolated/light lake-effect rain showers to stream
generally E'ward from the lake and impact the primary snow belt
of NE OH and NW PA toward and through daybreak. However,
lake-induced CAPE and equilibrium levels are expected to be
very marginal for lake-effect cumuliform clouds to be thick
enough to produce precip.
On Monday, the shortwave ridge exits E'ward by midday and is
followed by cyclonic W'erly to NW'erly aloft and embedded
shortwave troughs through daybreak Tuesday. The strongest of
these shortwave troughs is expected to move from the western
Great Lakes to New England between midday Monday and daybreak
Tuesday. At the surface, a trough lingers over our region and a
secondary cold front is forecast to sweep SE'ward through
northern OH and NW PA Monday afternoon through early evening.
Behind the front, a ridge builds very gradually from the north-
central United States and vicinity. This weather pattern at the
surface and aloft will maintain net low-level CAA across our
CWA. Limited daytime heating is expected to allow highs to reach
the 50's late Monday afternoon. Overnight lows are expected to
range from the lower 30's in southeastern Erie County and
eastern Crawford County to the mid 30's to lower 40's elsewhere
in NW PA. In northern OH, overnight lows are expected to reach
the mid 30's to lower 40's. Lows will be reached around daybreak
Tuesday.
Light lake-effect rain showers remain possible in the primary
snow belt of NE OH and NW PA through midday on Monday as the
aforementioned thermodynamic environment over Lake Erie changes
little and mean low-level flow varies between W'erly and
WSW'erly. During Monday afternoon through early evening,
scattered rain showers are possible along the cold front as it
sweeps SE'ward across our region and low-level convergence/ascent
along the front coincide with sufficient moisture and weak
potential instability in the lowest 1 km AGL. The best chance
for showers along the front exists over eastern Lake Erie and
across the primary snow belt of NE OH/NW PA as forcing for
ascent along the front combined with sufficient low-level
moisture and weak lake-induced CAPE result in somewhat steadier
lake-enhanced rain. Behind the front, 850 mb temperatures
fall to near -2C over ~14C Lake Erie amidst sufficient moisture.
Mean flow veers to NW'erly and then to N'erly and will allow
lake-effect rain showers to stream generally SE'ward and then
S'ward from Lake Erie. These lake-effect showers will likely
remain light as limited low-level moisture above 850 mb
contributes to weak lake-induced instability. Sufficient low-
level CAA and nocturnal cooling may allow a few wet snowflakes
to mix-in with rain after midnight Tuesday morning in southeastern
Erie County and eastern Crawford County in NW PA. However, no
snow accumulation is expected. Lake-effect precip is expected to
end by daybreak as low-level dry air advection and a lowering
subsidence inversion cause lake-effect CAPE to wane greatly.
&&
.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
Dry weather is favored for the majority of the short term period as
an upper ridge and surface high build over the region. Will
generally see a clearing trend with cloud cover throughout the day
Tuesday with high clouds returning as a warm front approaches from
the southwest during the day Wednesday. The warm front will lift
into the area Wednesday night and shower chances will begin to
increase on the western fringe of the forecast area in the last few
hours of the forecast period. With that being said, there's still
some uncertainty in how much moisture will be available, so it's
possible that a drier scenario with more virga than showers unfolds.
Tuesday will be the chilliest day of the week with highs in the 40s
and lower 50s and overnight lows in the 20s and lower 30s
anticipated. Temperatures begin to warm Wednesday and Wednesday
night and expect maximum temps in the 50s and minimum temps in the
upper 30s to lower 40s.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
An upper trough and surface cold front will cross the local area on
Tuesday, although there is still a bit of uncertainty in the exact
timing/track of the associated surface low as it tracks east
somewhere across the Great Lakes. Either way, most locations will
likely see at least a few light showers at some point early Thursday
morning through the afternoon. Lake-enhanced showers may continue
through Friday as upper troughing potentially persists across the
lower Great Lakes before drier weather returns for the majority of
the weekend as an upper ridge builds east from the Mississippi
Valley. The next system will begin to approach from the east at some
point late in the weekend, but still too much spread in extended
guidance to get specific with any potential precipitation timing.
Above normal temperatures are anticipated through the long term
period with temperatures in the 50s expected Thursday through
Sunday. A few spots may climb into the lower 60s on Sunday.
Generally expect lows in the upper 30s to lower 40s each night.
&&
.AVIATION /06Z Monday THROUGH Friday/...
Mainly VFR across the TAF sites early this morning with
deterioration to widespread MVFR ceilings later this morning
into the early afternoon. The first of two cold fronts has
exited east of the area, with the second and stronger of the two
expected to sweep southeast through the region later this
evening. Can't rule out isolated pockets of IFR ceilings, though
confidence remains too low at this time for any inclusion. Brief
rain showers will accompany the frontal passage later this
evening. Anticipate primarily VFR vsbys with the rain, though
can't rule out isolated pockets of MVFR vsbys.
Winds are generally out of the west to west-southwest early this
morning, 10 to 15 knots with periodic gusts of 20 to 25 knots.
Winds will gradually shift towards the west through today,
increasing to 15 to 20 knots with gusts of 25 to 30 knots by
this afternoon. Winds will then shift towards the northwest and
north behind the cold front this evening and remain elevated.
Can't rule out brief 30 to 35 knot gusts at TAF sites with the
frontal passage.
Outlook...Non-VFR possible in lingering lake-effect clouds
Tuesday morning. Non-VFR possible again in periods of rain
Wednesday night through Thursday.
&&
.MARINE...
Unsettled conditions will persist on Lake Erie through Tuesday as a
series of cold fronts cross the region. Southwest winds 20 to 25
knots are anticipated over the entire lake starting tonight, although
the open waters of the central and eastern basins may approach 30
knots overnight. The strongest winds are anticipated as the second
cold front moves over the lake late Monday afternoon into Monday
evening with sustained west to northwest winds of 25 to 30 knots
expected. Winds may briefly approach gale force in the open waters
east of The Islands with the frontal passage, but opted against any
gale headlines since winds will likely be in the 30 to 32 knot
range. Winds diminish to 20 to 25 knots late Monday night before
shifting to the northeast and diminishing to 10 to 15 knots by mid-
afternoon Tuesday.
Small Craft Advisories remain in effect for the entire lake through
Tuesday morning. Will need to keep an eye on the potential for a Low
Water Advisory in the western basin of Lake Erie, primarily with the
peak winds Monday evening. With that being said, winds may shift to
the northwest before water levels fall below the critical mark for
safe navigation (which is currently 9 inches above low water datum).
Can't completely rule out the water level at Toledo getting close to
the critical mark tonight, but would like to see winds trend a bit
higher than currently forecast.
Overall, quiet marine conditions are expected Tuesday evening
through most of Saturday. The next round of headlines may be needed
as offshore winds increase Wednesday night into Thursday, but as of
now forecast winds are below Small Craft Advisory criteria.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Small Craft Advisory until 10 AM EST Tuesday for LEZ142-143.
Small Craft Advisory until 1 PM EST Tuesday for LEZ144>149.
&&
$$
SYNOPSIS...Jaszka
NEAR TERM...Jaszka/Sullivan
SHORT TERM...Maines
LONG TERM...Maines
AVIATION...Kahn
MARINE...Maines
Source:
CLE issues Area Forecast Discussion (AFD) at Nov 11, 12:55 AM EST---------------
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