Area Forecast Discussion
Issued by NWS Cleveland, OH

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
378
FXUS61 KCLE 111214
AFDCLE

Area Forecast Discussion
National Weather Service Cleveland OH
714 AM EST Wed Dec 11 2019

.SYNOPSIS...
A ridge of high pressure over the region this morning will get
pushed south as a cold front moves through the eastern Great
Lakes this afternoon. Behind the front, high pressure will
reassert itself over the Ohio Valley for Thursday before moving
off the East Coast for Friday. A pair of low pressure systems
will then surround the region for the weekend, as a low moves
through the northwest Great Lakes, eventually merging with a
stronger low moves up the East Coast.

&&

.NEAR TERM /THROUGH THURSDAY/...
Minor changes to the forecast this morning. Added areas of
blowing snow to Erie County PA and Ashtabula County OH where
winds and moderate to heavy snow will impact the region later
this afternoon. Snow forecast remains on track at this time.

Previous Discussion...
Lake effect snow that prompted a Winter Weather Advisory on
Tuesday evening has moved north over Lake Erie this morning, as
low level winds have backed around to the southwest over Ohio
and Pennsylvania. These winds, along with drier air associated
with a ridge of high pressure extending in from the southwest,
will keep much of the forecast area dry for the morning hours,
as the focus for snow development will be over Lake Erie and
into western New York. Later this afternoon, a strong upper
trough will enter the Great Lakes region and the trough axis and
associated 500 mb vorticity maximum will swing through the
eastern Great Lakes, supporting a surface cold front. This front
will push the snow back south into the PA and OH Snow Belt
region this afternoon with moderate to heavy lake effect snow.
The thermodynamics for this event appear impressive for a
period. The cold air surging into the region will allow for the
convective boundary layer depth to grow to 8000 ft, help good
low level lapse rates and ascent in the DGZ, and the lake and
antecedent moisture will present fairly good saturation in the
low levels. All of this would indicate a period of heavy snow
around the evening commute, especially for Erie County PA. The
one limiting factor will be how quickly the arctic, continental
dry air will settle into the region. 850 mb moisture will
disappear quickly after dark and the inversion heights begin
decreasing quickly. With all of that said and the over-
performance of snow last evening, have extended the Winter
Weather Advisory for Erie County PA through 1 AM on Thursday.
The moderate to heavy snow, plus strong winds of 15 to 20 mph
with gusts to 35 to 40 mph, will bring a quick period of 3 to 5
inches of snow, which will also be blowing and drifting. Further
west into Ohio, there is less confidence on the extent of
snowfall as the dry air will enter more quickly. Have 1 to 3
inches of snow for Lake, Geauga, and Ashtabula Counties for now,
but these areas will need to be evaluated. Snow will continue
through the overnight, but any additional accumulations appear
to be very light after 1 AM. Temperatures will be in the 20s
during the day time hours and will fall back into the teens over
the region at night. This, along with some gusty winds with the
frontal passage, will allow for wind chills to fall into the
single digits for a period this evening.

The upper trough swings through and surface high pressure builds
into the region for Thursday. Dry air and lack of forcing will
make for a dry and partly cloudy forecast. Low level flow will
back around to the southwest during the day on Thursday and
temperatures will recover into the 30s for highs.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SUNDAY/...
High pressure will continue east towards the New England Coast
by Thursday night as a weak shortwave passes across the Upper
Great Lakes. Development of a low pressure system is expected
Friday across the Southeast and could impact the area with rain
by Saturday as the system slides northwards along the East
Coast. The ECMWF and GFS are similar with the timing of the low,
but somewhat differ in the placement and strength of the low
pressure center. By Saturday morning, the ECMWF solution has a
stronger and more inland-centered low while the GFS is slightly
weaker and just offshore the Delmarva Peninsula. At the same
time, another low pressure system is expected to dive down into
the Ohio Valley from the Northern Plains, increasing
precipitation chances in the western half by Saturday afternoon.
Precipitation will likely remain all rain for most of Saturday,
changing over to a rain/snow mix by Saturday night. As this low
passes east and drags a cold front across the area, increasing
westerly winds and an influx of colder air will lead to lake
effect rain and snow showers late Saturday night into Sunday
afternoon, turning to all snow by Sunday night.

Have increased low temperatures Thursday night into the upper 20s to
low 30s across the area due to cloudier conditions and increased
southerly winds. Highs will reach the mid 40s on Friday, low
40s on Saturday, then struggle to reach freezing by Sunday
following the cold frontal passage.

&&

.LONG TERM /SUNDAY NIGHT THROUGH TUESDAY/...
High pressure will move east across the region on Sunday night. Both
the 00Z GFS/ECMWF with some support from the Canadian model show an
upper level trough developing over the Rocky Mountains during this
time frame, then curling northeast towards the Eastern Great Lakes
Monday into Tuesday. Precipitation will accompany this system with
storm track critical to both precip types and temperatures. The
latest ECMWF favors a colder solution which would bring snow to
portions of the area while the GFS track is 200 miles to the
northwest and much warmer. Our official forecast will be on the
cooler side of the blend with just chance pops given a lot can
change with day 7 storm track and timing. Lake effect snows will
also be possible on the back side of this system.

&&

.AVIATION /12Z Wednesday THROUGH Sunday/...
A ridge of high pressure extends into the area this morning and
has pushed all lake effect snow out over Lake Erie and into
western New York. Some miscellaneous low clouds have entered NW
Ohio this morning and some brief MVFR ceilings are possible.
Otherwise, the area is VFR will just some high clouds about. The
main concern for today will be more snow that will enter the
snow belt region this afternoon and evening, especially around
KERI, as a cold front enters from the northwest. Snow will be
moderate to heavy in intensity with strong winds that will
present a blowing snow scenario. Have a window of MVFR snow in
the KERI TAF with a heavy hitting tempo group for moderate snow,
blowing snow, and LIFR conditions, as confidence is increasing
in poor aviation conditions this afternoon. Snow will depart
overnight and all areas should return to VFR. Winds with the
cold front will be briefly strong and gusts of 20 to 30 kts are
expected.

.OUTLOOK...Non-VFR possible Friday night into Saturday with a
snow/rain mix to start, before transitioning to all rain.

&&

.MARINE...
Southwest winds will ramp up today to 25-35 knots on Lake Erie ahead
of the next cold front that will slide south across Lake Erie this
afternoon. A Gale Warning remains in effect for the nearshore and
open waters generally east of Conneaut with 35 knot gales expected.
Small Craft Advisories remain in effect for the remaining nearshore
waters. As southwest winds ramp up today, water levels will drop on
the western basin of Lake Erie. The water level is expected to
approach but remain just above the critical mark for safe navigation
but will need to be monitored closely today. High pressure will
quickly build east across the lake tonight resulting in rapidly
improving conditions.

&&

.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...Winter Weather Advisory until 1 AM EST Thursday for PAZ001-002.
MARINE...Small Craft Advisory until 4 AM EST Thursday for LEZ142>148.
     Small Craft Advisory until 9 AM EST this morning for LEZ149.
     Gale Warning until 7 PM EST this evening for LEZ149-169.

&&

$$
SYNOPSIS...Sefcovic
NEAR TERM...Sefcovic
SHORT TERM...Kahn
LONG TERM...KEC
AVIATION...Sefcovic
MARINE...KEC



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.