CLE issues Area Forecast Discussion (AFD) at Dec 30, 1:00 AM EST157
FXUS61 KCLE 300600
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
100 AM EST Mon Dec 30 2024
.SYNOPSIS...
Low pressure over Northwest Ohio will pass north of Lake Erie
tonight, wrapping a strong cold front northeast across the area. As
this area of low pressure departs to the northeast on Monday, a
ridge will briefly extend north into the Ohio Valley. Another low
pressure system will track east through the Ohio Valley on Tuesday.
&&
.NEAR TERM /THROUGH TONIGHT/...
1:00 AM Update:
Extended the Wind Advisory to 4 AM for central and eastern
portions of the forecast area to give things a bit more time to
subside. Canceled the advisory out west where winds have
diminished (was going to expire at 1 AM anyways). Advisory from
Cuyahoga east continues until 10 AM, will evaluate those
expirations with the main package towards 4 AM.
Previous discussion...
A 991mb surface low is moving into NW Ohio with much of our forecast
area located in the warm sector. Meanwhile a negatively tilted
upper level trough is curling northeast across Indiana and
western Ohio late this afternoon. We have seen a break in the
stratiform rain across central portions of the forecast area
while forcing ahead of the mid-level dry slot has resulted in a
broken line of showers with isolated thunderstorms filling in
from near Tiffin to Columbus to Lancaster. There is roughly 100
J/kg of surface based CAPE as far north as Bucyrus and has been
slightly higher to the south where a few severe thunderstorm
warnings have been issued in the Wilmington Ohio forecast area.
We do expect to see this area of showers with isolated
thunderstorms move northeast towards Cleveland through about 6
PM but chances for stronger wind gusts being brought down to the
surface are reduced by the limited instability. The wind field
is very strong with 0-6km shear of 70-80 knots, but this may
actually be disrupting the weak updrafts to some extent. We will
be monitoring radar for any stronger bowing segments that could
produce severe winds but this window is only expected to last
through about 530pm. While a tornado can not be ruled out, the
0-3km shear vector has been nearly parallel to north to south
oriented bowing segments which is less favorable. Will be
watching for breaks in the line of showers or any more robust
convection which could pose a threat.
Stable conditions have limited any stronger wind gusts within the
wind advisory thus far today. However the strongest winds are
expected to be with the cold front this evening. The cold
front currently extends south to near Cincinnati. This front will
approach from the south after 6 PM with strong wind gusts
developing. The front is accompanied by good cold advection and a
rapidly strengthening pressure gradient as the low tracks north
of Lake Erie. Westerly winds will gust to around 45 mph along
the I-75 corridor with southwesterly winds gusting between 50-55
mph to the east. Considered a high wind warning for far eastern
portions of the forecast area where the low level wind field is
the strongest but would like to see more cooling and support
from the MOS guidance if we were to upgrade. With that said, can
not rule out a location or two seeing a wind gust to 60 mph.
Upstream radars depict a good swath of rain within the deformation
axis on the back side of this system. Rain will fill in on the back
side of this surface low as it passes north of Lake Erie, bringing
additional rain from northwest Ohio across northern portions of the
area. Observed precipitation with this system ranges from around
three quarters of an inch in the west to over an inch in north
central Ohio to less than a half inch in the east. Western and
northern areas can expect another .2-.4 inch of rain tonight
with lesser amounts in the southeast. So far rivers seem to be
handling the rain well with Larue in action stage and a few
others in the Great Lakes basin nearing action stage. We should
be able to handle the additional rain given mostly light to
moderate rates over the next 12 hours.
On Monday rain will depart from west to east as a ridge briefly
builds in from the south. We should see clouds clear from west to
east late morning through the afternoon before clouds thicken
again Monday night. Temperatures will be running about 15
degrees cooler than today. The break in active weather will be
short lived as the next area of low pressure approaches from the
west late Monday night. Could see rain just getting started
late Monday night towards Findlay but the bulk of the rain will
fall during the day on Tuesday.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Everything is still coming together for a significant pattern change
to classic mid-winter weather starting during the middle of the
week, ushered in by a fast moving storm system Tuesday into
Wednesday.
On Tuesday morning, an expansive mid/upper longwave trough trapping
a large pool of arctic air will be settling through the northern
Rockies, northern Plains, and northern Great Lakes as a significant
mid/upper shortwave trough progresses through 130+ knot H3 flow at
the base of this broad longwave trough. This shortwave and the
aforementioned strong jet will support a deepening surface low over
central Illinois and Indiana that will rapidly progress ENE across
the Ohio Valley during the day before the energy transfers to a
coastal low offshore of New Jersey and Long Island Tuesday night as
the longwave trough continues to deepen in its wake. Widespread rain
will overspread the area from SW to NE early Tuesday morning owing
to abundant moisture advection and isentropic ascent, so increased
the speed of the categorical PoPs moving into the region. The
surface low track has trended farther north during the day Tuesday,
with consensus now tracking it south of Lake Erie in the late
afternoon, so this will pull greater moisture into the region.
Consequentially, increased QPF a bit, with many areas seeing 0.25 to
0.50 inches of rain. We will need to monitor river levels for minor
or nuisance flooding due to the heavy rain that fell Sunday and
continued runoff with this rain added to it.
As the energy transfers to the East Coast Tuesday night, colder air
will start to quickly wrap in behind the system. Guidance has
continued to speed up this process, which makes sense given the
quickly developing NW flow behind the system and deepening longwave
trough. The NAM now shows H85 temps of -5 C by 09Z Wednesday, so
lowered temps from NBM guidance Tuesday night and changed the
lingering precip over to snow faster. The greatest moisture and
dynamics rapidly transferring to the coast will limit the intensity
of the snow, but with lingering mid-level frontogenesis (deformation
zone), NW upslope flow, and lake enhancement, there should be steady
light snow late Tuesday night and Wednesday morning. This will lead
to a couple tenths of an inch of snow in most areas, with 0.5 to up
to 1 inch in the higher terrain/upslope areas such as the central
highlands and primary and secondary snowbelts.
The coastal low will rapidly move up the coast of Maine by Wednesday
evening and into the Canadian Maritimes by Thursday, and this
combined with the deep longwave troughing elongated from the
northern Rockies through the Great Lakes will support an extended
period of broad cyclonic WNW flow and lake-effect snow downwind of
the lakes. Lingering lake enhanced snow over far NE Ohio and NW PA
Wednesday afternoon and evening will transition to pure lake-effect
snow Wednesday night as the cold air deepens. H85 temps cooling to
-12 to -14 C combined with lingering synoptic moisture over the 3 to
4 C Lake Erie surface water and well-aligned WNW flow will lead to
bands developing over the primary snowbelt east of Cleveland into NW
PA. There is already a hint of lake aggregate thermal troughing near
the south shore east of Cleveland as the boundary layer flow
gradually backs to more of a pure W flow Wednesday night, so a
fairly heavy west-east band could set up. Continued categorical PoPs
in the snowbelt for this potential. Snowfall rates will not be as
high as events early this season since the lake is colder now
(conditional instability vs extreme), but given the long fetch and
possible convergence, rates of 1 inch per hour are possible with
several inches of accumulation by Thursday morning. Exact band
placement is still uncertain 3.5 to 4 days out, but the pattern
supports a band over the eastern Lakeshore counties from Lake,
northern Geauga, and Ashtabula Counties into northern Crawford and
Erie Counties.
Tuesday will be the last mild day with highs in the low/mid 40s,
cooling into the mid 30s Wednesday. Lows Tuesday night will fall
into the low 30s, with low/mid 20s Wednesday night.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
As we have been messaging for several days, winter will be here to
stay in the long-term period as the deep and expansive longwave
trough becomes entrenched across the central and eastern CONUS in
response to a series of mid/upper ridges building into the West
Coast. The associated cold, cyclonic flow will continue Thursday
into the weekend, with a series of shortwaves shifting boundary
layer winds and lake-effect snow bands. Trended PoPs northeastward
toward the lakeshore of eastern Lake, Ashtabula, and Erie Counties
Thursday since the flow should back ahead of a stronger shortwave
dropping into the Great Lakes, but even colder air (850 mb temps of -
16 to -18 C) in the wake of this shortwave late Thursday night
through Saturday will keep lake-effect snow showers going as the
flow turns more west-northwesterly again. A weak surface response to
the Thursday night shortwave could lead to light snow over north
central Ohio around the central highlands and US 30 corridor. This
has been consistent in guidance the past several runs, so kept
chance PoPs down there. This will be monitored for possible
accumulations. There remains a good possibility of 6-12 inches of
snow over the primary snowbelt east of Cleveland through NW PA late
in the week into the weekend, with locally higher amounts where
squalls persist. Wind chills will also be in the teens to single
digits.
Weak ridging at the surface and aloft late Saturday into
Sunday may finally weaken the snow bands and push them toward
western NY, but light snow may develop areawide Sunday as isentropic
ascent increases ahead of another system. Deterministic and ensemble
guidance have significant uncertainty with the evolution of the next
system late next weekend/early the following week, so gradually
introduced areawide chance PoPs Sunday.
Highs will stay in the upper 20s to around 30 Thursday, with
generally low to mid 20s Friday through Sunday.
&&
.AVIATION /06Z Monday THROUGH Friday/...
Mainly MVFR has overspread the area as wrap-around rain wraps in
from the west. As this rain works east ceilings and vsby should
fall a bit more from CLE-MFD points east. The rain and vsby
restrictions will exit from west to east through this morning.
MVFR ceilings will generally prevail through most of today. Most
areas should see a break to VFR ceilings late this afternoon or
this evening before the next low pressure and associated
restrictions approaches from the west-southwest tonight.
Gusty southwest winds continue at 15-25kt with gusts 30-40kt
early this morning. Winds will gradually ease through today,
though gusts don't come out of play until later this afternoon
or early this evening at most sites.
Outlook...Non-VFR is likely in periods of rain and snow Tuesday
and Wednesday.
&&
.MARINE...
Strong low pressure will lift across the western basin of Lake Erie
this evening and into southeastern Ontario Monday morning, pulling a
strong cold front across the lake tonight. This will lead to SSE
winds this evening turning WSW tonight and increasing to 30-40 knot
gales as somewhat colder air starts to mix down with strong pressure
rises. The strongest winds will occur over the central and eastern
basins, building wave heights to 10-15 feet. Kept Gale Warnings
tonight into Monday morning east of the islands and through the
afternoon in the far eastern basin where winds will be slower to
diminish. Winds will reach 20-30 knots with higher gusts at times
west of the islands tonight, but likely staying just below gales.
Winds will quickly diminish Monday night before turning E to NE at
15-20 knots Tuesday as another low moves just south of Lake Erie.
The winds will turn NW to WNW Tuesday night and Wednesday and
increase to 15-25 knots as the low departs and a trailing cold front
crosses the lake. Mainly W winds of 15-25 knots, occasionally 30
knots, will then persist late Wednesday through Friday, so a long
period of Small Craft headlines will be needed.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Wind Advisory until 4 AM EST early this morning for OHZ009-010-
019>023-029>033-038.
Wind Advisory until 10 AM EST this morning for OHZ011>014-089.
PA...Wind Advisory until 4 AM EST early this morning for PAZ003.
Wind Advisory until 10 AM EST this morning for PAZ001-002.
MARINE...Small Craft Advisory until 1 PM EST this afternoon for LEZ142-
143.
Low Water Advisory until 10 AM EST this morning for LEZ142>144-
162>164.
Gale Warning until 7 AM EST this morning for LEZ144>148-
164>168.
Gale Warning until 4 PM EST this afternoon for LEZ149-169.
&&
$$
SYNOPSIS...KEC
NEAR TERM...KEC/Iverson
SHORT TERM...Garuckas
LONG TERM...Garuckas
AVIATION...Sullivan
MARINE...Garuckas
Source:
CLE issues Area Forecast Discussion (AFD) at Dec 30, 1:00 AM EST---------------
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