000
fxus61 kcle 181823
afdcle
area forecast discussion
national weather service cleveland oh
123 pm est mon jan 18 2021
.synopsis...
a trough will linger over the great lakes region today and
tonight. a faster moving trough will move southeast across the
great lakes tuesday night. high pressure will build through the
area wednesday and will remain in control over the region
through thursday. another trough will move southeast through the
great lakes during the friday into saturday timeframe.
&&
.near term /through tuesday/...
lake effect snow continues into erie county pa this afternoon,
although with a bit less intensity than earlier this morning.
will maintain the lake effect snow warnings as additional
amounts of 2 to 4 inches are possible through the end of the
warning at 1 am. totals across the region are already at 6 to 10
inches so some locations getting one foot of snow is now
expected once this round of snow is all said and done tonight.
elsewhere, snow remains fairly isolated/scattered but new
accumulations are light. another inch or two in the ne oh and nw
pa snow belts are possible through tonight. temperatures will
remain very stagnant near 30 degrees.
original discussion...
focus for the near term will be lake effect/enhanced snow
primarily impacting erie pa. a fairly potent snow band is
materializing offshore of ashtabula/erie counties this morning,
which right now is primarily impacting western ny. guidance
suggests this band will focus more over the northeastern part of
erie county through mid morning. although the thermodynamic
setup is marginal/fair, frictional low level convergence along
the lake/land interface will increase steadily over the next
several hours, with snowfall rates up to an inch per hour at
times. this may drop a quick 3 to 6 inches by this afternoon,
and will need to be closely monitored for locally higher amount
if the band becomes stationary for a period of time. have opted
to increase snowfall amounts and hold with the advisory, with
the higher accumulations expected to be concentrated to a small
area in the northeast part of the county. if higher amounts
become more widespread or increase in general, an upgrade to a
warning may be necessary. the convergence/forcing should weaken
a bit towards midday/early afternoon as the background flow
backs slightly, disrupting the organization of the bands with
more showery activity expected. hi-res guidance shows a strong
signal for reorganization of the bands this afternoon and
evening as the flow becomes better aligned, although some
uncertainty as to the location of the band has led to a bit more
conservative snowfall forecast for the afternoon/early evening.
have opted to extend the advisory through 1 am to cover this
potential. the bands should push into mainly western ny
overnight as the flow backs a bit further, but will be really
close to the erie shoreline overnight into tuesday, but should
disrupt and focus more into the buffalo area during the
afternoon.
elsewhere across the area, light snow along and northeast of a
cleveland to youngstown line will persist for a few more hours,
although any accumulations will be mainly a dusting to a few
tenths outside of the stronger lake effect band. additional snow
showers may develop this afternoon as a pv anomaly tracks east
across the area, with fairly steep low level lapse rates
developing east of the i-71 corridor. this could result in some
brief moderate snow showers, but in general snow accumulation
with this activity should be a half inch or less. mainly dry
conditions are expected outside of the lake band tonight into
tuesday, although another pv anomaly tracking across central oh
overnight into tuesday morning could bring some light snow to
the far southern portion of the forecast area. highs today will
again be in the low to mid 30s, and perhaps 1 or 2 degrees
colder on tuesday. lows tonight will be in the 20s.
&&
.short term /tuesday night through thursday night/...
westerly flow aloft becomes northwesterly tuesday night as a
shortwave trough moves eastward over the great lakes region and the
mid to upper oh valley, and a longwave ridge begins building behind
the shortwave disturbance. at the surface, a lake-aggregate trough
begins to be replaced by a surface ridge building from the west.
steady lake effect snow (i.e. les) should settle southward across
the snowbelt as the mean low-level flow veers from westerly to west-
northwesterly and synoptic-scale low-level moisture remains abundant
in the cold air mass. periods of heavy les are possible since model
soundings indicate strong ascent may be maximized in a cloudy dgz at
times. in general, les accumulations of 1 to 4 inches are expected
in the snowbelt, but slightly greater amounts are possible in
localized areas. additional winter weather headlines may be needed.
outside the les, isolated snow showers may accompany the
aforementioned shortwave trough and amount to less than one inch.
low temperatures should reach the upper teens to mid 20`s.
on wednesday, the high pressure ridge at the surface and aloft
continues building eastward, resulting in fair weather in most of
our cwa. lingering les should shift northward across the snowbelt
and exit the snowbelt by sunset as the low-level mean flow backs
from wnw toward sw. simultaneously, the les weakens as lake-induced
cape wanes via a lowering subsidence inversion and dry air advection
in the low-levels. any additional les accumulations should be an
inch or less. daytime highs should mainly reach the mid 20`s to
lower 30`s.
fair weather is likely in our cwa wednesday night as the ridge at
the surface and aloft exits to the east and a trough at the surface
and aloft approaches from the northwest. low temperatures should
reach the upper teens to upper 20`s, with the coldest readings in
interior northwest pa. on thursday, the trough will continue
settling over the great lakes and vicinity. at the surface, a cold
front should sweep eastward across our cwa as a low moves eastward
across northern on. models continue to suggest this cold frontal
passage will primarily be dry. however, a marginally-cold air mass
and westerly mean low-level flow may allow light lake-enhanced snow
and rain showers to impact the snowbelt. little or no snow
accumulation is expected as daytime highs reach the mid 30`s to
lower 40`s.
cyclonic westerly to northwesterly flow aloft and embedded shortwave
disturbances affect our cwa thursday night as the longwave trough
persists over the great lakes and vicinity. cold air advection
allows a lake-aggregate surface trough to develop over and near the
relatively-warm lakes, including our region. lake-enhanced snow
should evolve into pure les and continue affecting the snowbelt as
mean low-level flow veers from westerly toward west-northwesterly.
snow accumulations of several inches should occur as lows reach the
mid to upper 20`s. fair weather is expected outside the lake-
enhanced/effect snows.
&&
.long term /friday through sunday/...
aloft, cyclonic westerly to northwesterly flow and embedded
shortwave disturbances on friday should be followed by a high
pressure ridge building from the west friday night through sunday.
at the surface, the lake-aggregate trough should persist on friday
before a building ridge begins overspreading our cwa from the west
through the rest of the long-term period. les bands should continue
downwind of lake erie friday through saturday as the mean low-level
flow of cold air veers from wnw to nnw. this les should finally end
saturday night as a lowering subsidence inversion contributes to
waning lake-induced cape. at least several inches of fresh les
accumulation are possible. odds favor fair weather outside the les
through saturday night. on sunday, widespread light snow showers are
possible as broad isentropic lift aloft may begin overspreading our
cwa ahead of an evolving low pressure system over the western and
central u.s. temperatures should be near or slightly below-normal
through the period.
&&
.aviation /18z monday through saturday/...
widespread non-vfr continues across the region this afternoon as
a surface trough lingers near lake erie and ample low-level
moisture remains in the region behind an upper level trough.
expect mvfr to continue for most with intermittent light snow
showers as a weak shortwave aloft ripples through the region
this afternoon. in ne oh and nw pa, ifr or lower expected at
terminals where lake effect snow will continue through tuesday,
especially keri where lake effect snow has lashed the terminal
over the last 10 hours. lake snow will diminish on tuesday and
become more scattered and have improving conditions for keri for
now. winds will remain a variance of west to southwest across
the region, although some stronger gusts are possible on
tuesday, especially keri and kcle.
outlook...non-vfr possible through wednesday morning and then
again wednesday night into thursday morning. non-vfr possible
friday.
&&
.marine...
a small craft advisory is in effect from 1 pm today to 7 pm est
wednesday from willowick to ripley. in addition, a small craft
advisory is in effect from 4 pm tuesday to 7 pm est wednesday from
vermilion to willowick.
marine conditions will tend to be unsettled on lake erie through
friday as a series of troughs affect the lake. these unsettled
conditions include the expectation of westerly winds as strong as 15
to 25 knots and waves as large as 3 to 8 feet in the central and
eastern basins today through at least wednesday morning. a brief and
relative lull in winds and waves may affect the lake wednesday
afternoon and early evening in association with a high pressure
ridge. conditions should then deteriorate once again later wednesday
through friday.
&&
.cle watches/warnings/advisories...
oh...none.
pa...lake effect snow warning until 1 am est tuesday for paz001-002.
marine...small craft advisory until 7 pm est wednesday for lez147>149.
small craft advisory from 4 pm tuesday to 7 pm est wednesday
for lez145-146.
&&
$$
synopsis...greenawalt
near term...greenawalt/sefcovic
short term...jaszka
long term...jaszka
aviation...sefcovic
marine...jaszka