CLE issues Area Forecast Discussion (AFD) at Dec 8, 9:11 PM EST665
FXUS61 KCLE 090211
AFDCLE
Area Forecast Discussion
National Weather Service Cleveland OH
911 PM EST Sun Dec 8 2024
.SYNOPSIS...
A warm front lifts northeast across the region tonight before a
cold front tracks through on Tuesday. Cooler weather with
increased snow chances Wednesday and Thursday.
&&
.NEAR TERM /THROUGH MONDAY NIGHT/...
910 PM EST Update...
The forecast remains on track and no changes were needed with
this update. Still expect rain to arrive from the southwest late
tonight or very early Monday morning before widespread rain
exits to the east Monday afternoon.
Previous Discussion...
Upper level trough will kick out of the southern plains region
into the Ohio Valley tonight with a surface warm front tracking
across the CWA southwest to northeast. Will have a band of PVA
aloft out ahead of the overrunning, and could see some sprinkles
in advance of the made shield of stratiform rain that will come
with isentropic ascent. Low level moisture advection being
utilized in the off surface lift where precipitable water values
are in the area of one inch, on the higher side for December.
No warm cloud processes, so not looking at unmanageable QPF, but
now looking at half to one inch for most locations. System
should be progressive enough that it does not cause too many
issues, but the snowbelt areas where 1-2ft of snow remains on
the ground will need to be watched. Rain should be out of the
eastern CWA before the dewpoints get into the mid 40s, so the
snow on the ground is more likely to hold some of the QPF, at
least at first. Do not expect all of the snowpack to be gone
with this first round of rain in the forecast. The hope remains
that the snowmelt is balanced through the near and short term
period to prevent hydrologic issues, but ponding in those areas
should be expected. Drying out for a short period late Monday
through Monday night while the next upper trough axis organizes
over the plains region. Temperatures mainly lower 50s, with mid
to upper 40s on Monday where snow remains.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
An active short term period is in store as a potent upper-level
trough will move east across the central and eastern CONUS Tuesday
into Wednesday. At the surface, a low pressure system is expected to
develop along the spine of the Appalachians Tuesday night and deepen
as it reaches southern Quebec Wednesday night. Large uncertainty
remains on the evolution of this system. At this point, the best
chance for precipitation on Tuesday appears to be along and east of
the I-71 corridor. A weak cold front will be slowly moving east
through the area on Tuesday which could result in snow mixing in
with the rain Tuesday evening and overnight.
As mentioned above, there remains large uncertainty on the evolution
of the low pressure system as it rapidly deepens across New England
into southern Quebec Wednesday into Wednesday night. Simultaneously,
a strong cold front will be sweeping east through the region on
Wednesday, which will usher in perhaps the coldest air of the season
thus far. Any precipitation that falls on Wednesday will likely be
snow, although any accumulations should be limited to around an inch
or less. Behind the strong cold front Wednesday night, 850 mb
temperatures will plummet to -15 degrees C, setting the stage for
another round of lake effect snow along the primary snowbelt. More
details to follow in the long term section. In addition, single
digit to near-zero wind chills are likely, with perhaps a few sub-
zero wind chills possible late Wednesday night into early Thursday
morning.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
The arctic air mass will remain overhead on Thursday, as 850 mb
temperatures fall further to near -20 degrees C. High temperatures
will only reach the upper teens to lower 20s with daytime wind
chills in the single digits likely. A mid-level shortwave is
expected to traverse the base of the larger upper-level trough
Thursday morning which could enhance any existing lake effect snow
bands across the primary snowbelt. The location of the lake effect
snow will be similar to that of the Thanksgiving event (closer to
the lakeshore), though the magnitude will be lower. Still some
uncertainty on where the snow bands will develop, with model
disagreement on the strength of the thermal lake-aggregate trough.
BUFKIT soundings do indicate the potential for two dominant single
bands to develop on Thursday, one with a more WSW component
impacting western NY, and one with a more W component impacting
portions of the primary snowbelt in Northeast OH and Northwest PA.
Blowing snow does appear more likely with this event, given the
higher snow ratios (near 20:1) in addition to gusty W to WSW winds
of 35 to 40 mph. Watches may be needed in future forecast iterations
if trends continue.
The arctic air mass will begin to lift on Friday, though single
digit to near-zero wind chills will remain likely early Friday
morning. A weak ridge will attempt to build across the Eastern
CONUS late Friday into Saturday, signaling an end to lake effect
snow across the snowbelt. However, a weak upper-level trough appears
favored to replace this ridge late Saturday into Sunday which could
result in another round of rain and/or snow showers with
temperatures at or just below normal in the upper 30s to lower
40s.
&&
.AVIATION /00Z Monday THROUGH Friday/...
Conditions will gradually deteriorate from the west/southwest
starting at about 04Z tonight with a period of MVFR ceilings
anticipated before ceilings/visibility drop to IFR and possibly
lower as rain overspreads the local area early Monday morning.
Widespread rain should exit to the east by about 18Z Monday
afternoon, but some patchy drizzle/mist may persist for a few
hours after the rain ends. Regardless, MVFR/IFR in low stratus
will continue at all TAF sites through 00Z Tuesday.
Winds will be out of the south at about 6 to 12 knots tonight
before shifting to the southwest and increasing by a few knots
Monday morning. A few gusts to 20 knots are possible at western
terminals where there is a slightly higher chance of mixing.
Outlook...Non-VFR expected late Monday through Tuesday in low
ceilings/rain. More non-VFR expected in post cold frontal
snow/lake effect snow in Northeast Ohio and Northwest
Pennsylvania Wednesday through Thursday and possibly into
Friday.
&&
.MARINE...
A generally quiet marine period is anticipated through Tuesday with
offshore flow of 15 to 20 knots favored. A strong cold front will
sweep east across the lake on Wednesday, ushering in westerly winds
to 30 knots and necessitating the return for at least Small Craft
headlines into Friday. Confidence is increasing for westerly Gales
behind this cold front, particularly Wednesday night into Thursday
and will be something to continue to monitor.
The strong cold front will usher in an arctic air mass across the
lake, with air temperatures in the mid-20s. Lake surface
temperatures in the 40s in addition to marginally-cold air
temperatures across the lake should largely limit any freezing spray
concerns, but will be something to monitor in future forecast
updates.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...None.
&&
$$
SYNOPSIS...26
NEAR TERM...Maines/26
SHORT TERM...Kahn
LONG TERM...Kahn
AVIATION...Maines
MARINE...Kahn
Source:
CLE issues Area Forecast Discussion (AFD) at Dec 8, 9:11 PM EST---------------
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