NWS Cleveland, OH wrote its last area forecast discussion before the first event at Dec 18, 10:47 AM EST, 1 hour 13 minutes earlier.
Area forecast discussion, Dec 18, 10:47 AM EST, 1 hour 13 minutes before
Area Forecast Discussion
National Weather Service Cleveland OH
1047 AM EST Mon Dec 18 2023
.SYNOPSIS...
A strong low pressure will track north from the mid-Atlantic across
New England today. Meanwhile an upper level trough will dive south
across the Great Lakes region bringing an influx of colder air. High
pressure will expand north up the Ohio Valley on Tuesday and remain
over the Appalachians through Thursday.
&&
.NEAR TERM /THROUGH TUESDAY/...
9:30 AM Update...
Increased PoPs in most of the area this morning, as well as
this afternoon and tonight since everyone will see precipitation
from now through at least mid evening. The axis of the mid/upper
trough and associated H5 low is currently crossing southern
Michigan and northern Indiana, with an impressive signature on
water vapor loops. The associated cold front/surface trough will
move east/southeast across our region the rest of the this
morning through mid afternoon. A band of snow squalls is already
developing along this feature in northern Indiana, aided by Lake
Michigan moisture, and expect these snow showers to expand in
coverage and move into the western and northern tier counties by
early afternoon. Light rain mixing with wet snow and occasional
graupel is already expanding over Lake Erie and most of northern
Ohio ahead of the mid/upper trough axis and associated surface
boundary, and expect a fairly quick transition to snow this
afternoon as 850 mb temps cool and wet bulbing also helps to
drop surface temps. Most areas will be seeing wet snow by 18Z
except near the lakeshore east of Cleveland to Erie, PA where a
rain/snow mix will continue. Roadways should just remain wet
this afternoon, but that will change around sunset, during the
evening commute.
A secondary surface trough will cross Lake Erie in the 23-01Z
timeframe bringing the true cold air with 850 mb temps falling
to -10 to -14 C behind it for tonight. This boundary will bring
a burst of lake enhanced snow to all of north central and NE
Ohio into NW PA this evening, with scattered snow showers from
Lake Michigan continuing in NW Ohio. Saturation and strong lift
through the DGZ combined with the boundary layer flow turning
NW will lead to moderate to heavy snowfall over the upslope
areas of the primary and secondary snowbelt for several hours
this evening. Stronger winds near the lakeshore will lead to
lighter snow and far less accumulation, but the aforementioned
inland areas will see several inches this evening making roads
hazardous, even as far south as Akron/Canton. By 02 or 03Z,
strong cold air advection, well-aligned NW boundary layer flow,
and lingering wrap around moisture and lift within the DGZ will
support moderate lake induced instability for a transition to
lake-effect snow. Multiple bands of snow showers will bring
additional accumulations to inland portions of the primary
snowbelt and the secondary snowbelt overnight, with the heaviest
amounts tied to wherever a Lake Huron feeder band sets up. HREF
members are suggesting that this band will wobble near the
county lines of Ashtabula, Trumbull, Erie, and Crawford Counties
most of the night, but it could briefly move as far west as
Lake and eastern Geauga Counties. This warrants near 100 PoPs
for inland snowbelt areas much of the night. NW winds gusting
between 25 and 35 mph will lead to blowing snow, especially
across areas east of Cleveland through PA.
Storm total snowfall continues to look reasonable given the
aforementioned factors, with 2 to 6 inches in most of the
secondary snowbelt from southern and eastern Cuyahoga through
Medina, northern Summit, and Portage Counties, with lighter
amounts of 1-3 inches along the lakeshore from Cleveland to
Erie, PA. The big winners will be Geauga, inland Ashtabula,
southern Erie, and Crawford Counties where 5-9 inches will occur
in many places, with locally up to 12 inches where the Huron
band persists. Stayed with 2-5 inches in Trumbull County, but if
the Huron band gets in there, amounts will be locally higher.
Outside of these snowbelt areas, most areas will see anywhere
from a half inch to 2 inches, mainly this evening. Lake-effect
snow showers will quickly weaken and shift east Tuesday morning
as surface ridging builds into the area.
Original Discussion...
Water vapor imagery shows the upper trough moving south over
Lake Michigan. Precipitation has been expanding across lower
Michigan in response to this feature. We are also seeing
temperatures in NW Ohio solidly in the mid 30s with 33 already at
MFD. No significant changes made to the forecast with this
update but these trends may support more of a wet snow then a
rain/snow mix.
Previous discussion...Wintry conditions expected to return
during the near term with falling temperatures, rain
transitioning to snow today, and heavy snow with blustery
conditions for portions of the area tonight. A cold front moved
through the area overnight and much colder air will continue to
filter into the region through tonight as strong low pressure
tracks from the Mid-Atlantic north through New England. A
surface trough extends back across the Great Lake Region which
will tighten up today and tonight as a potent upper level trough
closes off overhead. Rain showers will expand through the
morning as large scale lift and moisture ramp up ahead of this
trough. Temperatures are already into the upper 30s to lower 40s
and not expected to climb today as cold advection increases
with the strengthening pressure gradient and wind field.
Temperatures at 850mb range from -1 to
-6C this morning and will fall to between -6 to -11C by 00Z
tonight as colder air originating over the Upper Midwest is
pulled southeast around the lakes.
Precipitation today will be almost convective in nature at times as
mid levels undergo more drastic cooling with the arrival of a -35C
cold pool at 500mb. Showers will steadily fill in late this morning
into this afternoon. Precipitation will be a wet rain/snow mix and
could see occasional graupel mixing in. The timing of the transition
to snow is hard to pin down given the variable precipitation rates
and likelihood for higher elevations to change over to snow first.
The overall trend has been for the cooler air to arrive earlier,
allowing for more of the precipitation to fall as snow vs rain and
resulting in a higher snowfall forecast. In general, a rain/snow mix
is likely through midday with most areas changing over to snow
through 4 PM although lakeshore areas could lag slightly. Always
questionable how long it will take for snow to start to accumulate
given the wet ground, but in this case think most areas will see
accumulations by sunset if not sooner given high precipitation rates
and the loss of insulation.
A window of moderate to heavy snow is expected during the evening
commute and untreated roads could quickly become snow covered in the
Advisory/Warning area as the center of the upper low passes just
south of Lake Erie. Strong lift and enhanced snow will move in off
the lake with widespread snow developing. Snow will be enhanced for
several hours into the overnight as shortwaves continue to move
south through the upper trough and good lift continues in the
dendritic growth zone through at least 3 AM. The earlier start makes
for a little longer duration of good quality snow then what was
expected in previous days leading to the upward trend in the
snowfall forecast. Moisture depth is good through at least 12Z
before diminishing across the headline area through the morning.
Model soundings show steep lapse rates from the surface to
nearly 18K feet for several hours. This will lead to high
precipitation rates but somewhat uncertain in the quality of the
snow. Overall don't think this will limit amounts too much with
qpf of 0.6 to 1.00 across the warned counties. Decided to go
with a winter storm warning instead of a Lake Effect Snow
Warning as the coverage of snow will be pretty widespread across
the snowbelt tonight. It will certainly be enhanced by the
lakes but this dynamic upper low is the bigger driver for
precipitation. We do expect to see a band set up off Lake Huron
and high resolution models are now in better agreement focusing
it towards Ashtabula/Erie/Crawford Counties. Higher snowfall
amounts are not out of the question where this band sets up.
Otherwise, upslope areas will be favored with northwest flow
through the duration of the event. In addition, winds will be
strong tonight with a 40-50 knot jet at 850mb sliding from lower
Michigan towards Central Ohio. Gusts of 30-40 mph are possible
tonight and the strong winds may focus the heavier snow farther
inland from Lake Erie which is part of the reason the lakeshore
counties are only in an Advisory. As accumulations start to pile
up, these strong winds will also contribute to some blowing of
snow. Temperatures will fall into the 20s tonight so snow ratios
become much higher later in the event, transitioning from an
early 8:1 to 16:1. Wind chills will be chilly as they fall into
the low teens for most areas by Tuesday morning. The falling
temperatures may also result in some ice forming under the snow
as the first coating will be a wetter layer with drier snow
falling on top of it.
Snow will diminish rather quickly on Tuesday morning as moisture
pulls away from west to east. Cloud depth decrease rather quickly
and snow rates will be much lighter. The Warnings last a little
longer in Pennsylvania where a Lake Huron band may still be a
factor. Otherwise, western areas will see sun by Tuesday morning,
expanding east through the afternoon. Wind chills will be brisk
through Tuesday morning but winds drop off Tuesday afternoon as high
pressure builds into the Ohio Valley.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
An upper level ridge and associated surface high pressure will begin
to push into the area Tuesday night and is expected to be the
primary influence of weather through the short term period, marking
the return of dry conditions across the area with partly cloudy
skies. Clearing on Tuesday and Wednesday nights will result in the
the low temperatures dropping into the low to mid 20s. Increasing
clouds on Thursday night ahead of the next system will keep
temperatures a bit milder, only dropping into the upper 30s to low
30s. High temperatures through the period will linger in the low
40s.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
Looking ahead to next weekend, including the Christmas holiday,
chances of precipitation return, but unfortunately (in regards to a
white Christmas) looks to remain all rain. The first chance of rain
comes Friday evening into Saturday as a surface low over the central
US extends a warm front towards the area. Overall support from the
upper levels remains marginal, so not expected any heavy rain and
conditions should mostly dry out on Saturday and Sunday as a ridging
pattern lingers over the Great Lakes region. Chances of rain return
Sunday night into Monday as another surface low tracks northeast out
of the southern Plains. Overall confidence in the timing and extent
of showers remains low as models diverge quite a bit in handling the
deepening upper level trough and its progression eastward.
Temperatures through the period will begin in the low 40s, but
increase into upper 40s to low 50s by Christmas Day as a WAA regime
becomes established. Overnight lows will drop into the mid to upper
30s. These temperatures will be above normal for this time of
year.
&&
.AVIATION /12Z Monday THROUGH Friday/...
A few light rain showers have been ongoing across the area
overnight, mainly focused across the snowbelt region.
Temperatures will continue to fall today into tonight as colder
air filters into the region. Ceilings are primarily MVFR but
may drop to IFR at times, especially in heavier bursts of
precipitation today. Showers will fill in this morning as a
compact upper level low approaches the region from the
northwest. best chances at NE Ohio terminals. Showers will
start as a rain/snow mix in the west and rain in the east but
the transition to snow has been trending faster with most areas
seeing snow by 18-21Z. Some locations may change over to snow
faster in heavier bursts then change back to rain before a final
transition to snow occurs this afternoon. Sites at higher
elevations like MFD may also transition a little faster than
surrounding terminals. Visibilities will fluctuate considerably
with the rain/snow mix, sometimes dropping to a mile or less.
Winds become rather gusty during the afternoon with northwest
winds gusting to between 25-35 knots. A trough is expected to
cross Lake Erie after 00Z with all eastern terminals seeing a
period of snow. Snow on Monday night will be moderate to heavy
at times with visibilities dropping below a mile at times at
CLE/ERI/YNG/CAK and perhaps MFD. Best windows of showers and
heavier snow will need adjusted but the trend will be for
blustery conditions and occasional IFR. Some improvement will
start to work into CLE by 09Z and by YNG by 12Z.
Winds will increase this morning with westerly winds starting
to gust to 20-25 knots. Winds shift to the northwest with the
passage of a trough between 15-22Z. The strongest winds will be
in NW Ohio and at terminals closer to Lake Erie where gusts to
30-35 knots are possible at times.
Outlook...Non-VFR conditions will continue into Tuesday morning
with occasional snow showers still at YNG/ERI and possible CLE.
&&
.MARINE...
A deepening low pressure system moving up the East Coast is expected
to bring hazardous marine conditions across Lake Erie beginning this
morning and continuing into Tuesday, with the primary concern being
strong winds and subsequent high waves. Winds will begin to ramp up
from the west-northwest this morning to 20-25 knots by 15Z for all
basins. These winds will intensify to gales across the western and
central basin by and 25-30 knots for the eastern basin. This strong
onshore flow will result in waves building to 5-10 feet, with the
highest waves expected in the central basin up to 12 feet. One
important thing to note is how the headlines are laid out for this
period. A Gale Warning goes into effect at 15Z for the western and
central basins which is also accounting for the ramping up period
before gales are reached this evening. The Gale Warning will
continue through 09Z Tuesday for those highlighted basins, which
will then be replaced by a Small Craft Advisory that will likely
extend into Tuesday evening. For the eastern basin, a Small Craft
Advisory for the lakeshore zones will be in effect through the
duration of the event, but with this update opted to extend it until
00Z Wednesday.
As the aforementioned low pressure moves northeast towards Nova
Scotia, high pressure will build across the Great Lakes region and
allow calmer marine conditions to move in. For Tuesday night, winds
will shift to become southwesterly at 10-15 knots which will persist
into Thursday. By Thursday winds become 5-10 knots from the south
gradually shifting to become east-southeasterly by Thursday night.
These light winds are expected to persist into the weekend.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Winter Weather Advisory until 10 AM EST Tuesday for OHZ011-012-
020>023-089.
Winter Storm Warning until 10 AM EST Tuesday for OHZ013-014.
PA...Winter Weather Advisory from 3 PM this afternoon to 10 AM EST
Tuesday for PAZ001.
Winter Storm Warning from 3 PM this afternoon to 1 PM EST
Tuesday for PAZ002-003.
MARINE...Gale Warning until 4 AM EST Tuesday for LEZ142>147-162>167.
Small Craft Advisory until 8 PM EST Tuesday for LEZ148-149.
&&
SYNOPSIS...KEC
NEAR TERM...KEC/Garuckas
SHORT TERM...Campbell
LONG TERM...Campbell
AVIATION...KEC
MARINE...Campbell