CLE issues Area Forecast Discussion (AFD) at Dec 6, 9:30 AM EST405
FXUS61 KCLE 061430
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
930 AM EST Fri Dec 6 2024
.SYNOPSIS...
High pressure builds from the west for Friday and Saturday. A
warm front lifts across the area on Saturday night with our next
low pressure system arriving Monday.
&&
.NEAR TERM /THROUGH SATURDAY/...
9:30 AM Update...
A ridge of high pressure will continue to build east into the
forecast area through today. This ridge will allow for winds to
back southwesterly through today and push any remaining lake
effect snow east towards Northwest Pennsylvania. By later this
evening, anticipate for a more organized single lake effect
snow band to primarily impact northern Ashtabula County in Ohio
and Northwest Pennsylvania through tonight.
Previous discussion...
Latest observations show lake effect snow gradually
dissipating, though a thin band of accumulating snow extending
from Lake Huron continues into parts of Northwest Pennsylvania.
Light scattered snow showers also linger in parts of Northeast
Ohio, though little to no accumulations are expected with this.
Because of this, all Ohio winter headlines (except Ashtabula)
have been cancelled.
High pressure builds in across the Ohio Valley, and as it does
so, steering flow should gradually shift from north-northwest
early this morning to westerly by early this afternoon and then
west-southwest this evening into tonight. Lake effect snow off
of Lake Michigan in northern Indiana will shift eastward, with
a period of scattered, light snow showers moving east across
parts of northwest Ohio and north-central Ohio this morning. The
Huron connection likely shifts eastward out of Northwest
Pennsylvania but new lake effect snow develops across parts of
Lake, Geauga, Ashtabula, and into Northwest Pennsylvania this
afternoon. While temperatures aloft are on the upward trend,
they remain sufficiently cold for enough lake-induced
instability. This lake effect snow should be rather brief for
areas such as Lake, Geauga, southern Ashtabula and most of
Crawford with 1-2" of additional snow expected in these areas.
Snow should be more persistent in far northeast Ashtabula, the
northern fringes of Crawford, and especially Erie County where
an additional 4 to 6 inches through Friday night area expected.
Latest model soundings suggest that lake effect snow bands may
only just barely be tapping into the dendritic growth zone, so
snow ratios may not be as high as they have been the past
several days. There could be some light lake effect lingering
into northern Erie Saturday morning but model consensus suggests
it moves offshore Lake Erie by 12Z Saturday. Weak clipper good
bring a glancing blow of snow Saturday afternoon/evening mainly
for Northwest Pennsylvania and likely to only be a few tenths of
snow accumulations at best. Lake effect snow warnings for
Ashtabula, Erie, and Crawford will continue through tonight.
Outside the snowbelt region, high pressure that builds in from
the south, so should see gradually improving conditions in the
way of more sunshine and gradually warming temperatures (i.e.
highs just below freezing this afternoon, and then into the mid
30s by Saturday afternoon).
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
A very active pattern will continue through the start of next week,
but the good news if you don't like snow is that temperatures will
be trending much milder.
Starting off Saturday night, another fast moving Clipper system will
drop through the northern and eastern Great Lakes. The upper jet
support will largely remain NE of the region, but the tight pressure
gradient between the fairly deep 998 mb surface low and strong 1024
mb surface high centered over the Tennessee Valley will lead to
gusty SW winds late Saturday night and Sunday, especially along the
lakeshore and in NW Ohio. Expect SW winds to increase to 15-20 knots
with gusts of 25-30 knots, peaking Saturday night and Sunday
morning. The pressure gradient will relax Sunday afternoon as the
low exits the coast of New England and mid-level heights quickly
rise across the Ohio Valley and southern Great Lakes. A few
rain/snow showers are possible in far NE Ohio and NW PA Saturday
night into Sunday morning, but most areas will stay dry.
The true rain chances will come Sunday night into Monday as a
northern stream mid/upper trough deepens across the Rockies and
Plains, picking up a southern Plains closed low. This southern low
will then open up into a trough and eject across the Ohio Valley
Sunday night and Monday, essentially acting as a lead piece to this
system. Strong moisture advection and isentropic ascent as a warm
front lifts across the region will bring a period of fairly steady
showers Sunday night and Monday morning before we get into the warm
sector Monday afternoon as the lead trough exits the region.
Guidance is coming into better agreement on this scenario, which
will keep QPF at manageable levels (0.25 to 0.50 inches). There
could still be some minor flooding where a deep snowpack will be
melting over the primary snowbelt of far NE Ohio and NW PA, but
otherwise, no impacts are expected. As the main mid/upper trough
further deepens and progresses across the Plains and into the
Mississippi Valley Monday night, the associated cold front will
slowly push into the region as the surface low lifts well north
toward Hudson Bay. Not expecting much additional rainfall with the
cold front Monday night into Tuesday other than light showers, but
the strong amplification of the central CONUS trough and east coast
ridge will make for a very slow frontal passage, so will need to
watch for a surface wave of low pressure to possibly develop and
ride up the front around Monday night/Tuesday which could bring
better rainfall. This is uncertain.
Highs will warm into the mid/upper 40s in most areas Sunday and
upper 40s/low 50s Monday. Slightly cooler in far NE Ohio and NW PA.
Lows Saturday night will fall into the upper 20s/low 30s, with
low/upper 30s Sunday night and Monday night.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/...
The large central CONUS mid/upper trough will gradually progress
into the Great Lakes Tuesday through Wednesday. This will push the
cold front slowly through the rest of the region Tuesday, but as
mentioned above, guidance is hinting at a possible wave of low
pressure that could bring better rainfall coverage and slow the
front even further. Given the uncertainty, have higher PoPs in
eastern Ohio and western PA Tuesday. Temperatures will plummet
behind the cold front later Tuesday through Wednesday as another
surge of arctic air drops through the Great Lakes. Wraparound
moisture and broad cyclonic flow as the mid/upper trough axis
crosses the Great Lakes will bring lake-effect snows to the favored
snowbelts Tuesday night into Thursday, but cannot pinpoint wind
directions at this time, so just included broad likely PoPs in NE
Ohio and NW PA. The lake-effect snow showers should gradually
diminish Thursday as ridging attempts to build in from the west.
&&
.AVIATION /12Z Friday THROUGH Tuesday/...
A very light snow showers in Northeast Ohio counties continue to
dissipate, though a Huron band should continue to produce lake
effect snow across Northwest Pennsylvania through at least this
morning. Lake effect cloud will persist across Northeast Ohio
however, with ceilings in the 3-5kft range. Steering flow
currently out of the north-northwest will veer to the west today.
This will allow the Lake Michigan lake effect snow to traverse
parts of northwest and north-central Ohio, producing brief
periods of MVFR ceilings and light snow showers during the
morning hours. For the lake effect downwind of Lake Erie, the
main Lake Huron band will shift east out of Northwest
Pennsylvania with a new lake effect snow band developing along
the lakeshore counties (e.g. mainly Lake, Ashtabula, and into
Northwest Pennsylvania) this afternoon into tonight. This snow
could be heavy at times and KERI would be the primary TAF site
affected by this. It's uncertain how much KERI is affected as
some models keep it to the south of the airport will moderate to
heavy snow after 00Z. Some models have moderate to heavy snow
beginning earlier in the afternoon. For now, have various
periods of 2SM snow though visibility could drop to as low as
1/4SM at times.
For winds, 7-12 knots of northwest winds (with gusts to 20
knots) becomes west this morning with slightly stronger winds
of 11-13 knots (with gusts to 20 knots or so) by this afternoon.
Slightly stronger winds are expected closer to the lakeshore.
Winds become southwest tonight weakening to around 7 to 10
knots.
Outlook...Non-VFR may continue through Saturday for Northeast
Ohio and Northwest Pennsylvania with lake effect snow showers
across the Snowbelt region. Non-VFR possible with rain is
expected as a low pressure system crosses the region on Monday
and Tuesday.
&&
.MARINE...
Active weather will continue on Lake Erie over the next 5 days. The
winds on the western basin will diminish slightly this morning,
however, an areawide increase is expected this afternoon into
tonight as winds turn WSW and increase to a solid 15-25 knots. The
Small Craft Advisory between the Islands and Vermilion may need to
be extended into tonight, but the Small Craft Advisories for the
central and eastern basins will continue into Monday as winds turn
more SW over the weekend and remain solidly 15-25 knots. A low end
Gale is possible Saturday night and Sunday as the pressure gradient
tightens, where SW winds increase to 25-30 knots, approaching 34
knots at times. This will be monitored. Winds will slowly decrease
Monday and Tuesday while gradually turning more westerly.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...Lake Effect Snow Warning until 1 AM EST Saturday for OHZ014-
089.
PA...Lake Effect Snow Warning until 1 AM EST Saturday for
PAZ001>003.
MARINE...Small Craft Advisory until 4 AM EST Saturday for LEZ144.
Small Craft Advisory until 7 AM EST Monday for LEZ145>149.
&&
$$
SYNOPSIS...Saunders
NEAR TERM...Iverson/Saunders
SHORT TERM...Garuckas
LONG TERM...Garuckas
AVIATION...Saunders
MARINE...Garuckas
Source:
CLE issues Area Forecast Discussion (AFD) at Dec 6, 9:30 AM EST---------------
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