NWS Area Forecast Discussion

000
FXUS61 KBUF 252328
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
628 PM EST Thu Feb 25 2021

.SYNOPSIS...
A weak system tracking in from the Upper Great Lakes will help
flare up the lake effect east of Lake Ontario tonight through
daybreak. Will be a dry end to the work week though, then
another low pressure system will bring some rain and snow to the
region Saturday. Our region will become progressively milder as
we head into the weekend.

&&

.NEAR TERM /THROUGH FRIDAY/...
Tonight, colder air remains with H85 temps -10c to -12c across the
region. Weak system tracks in from the Upper Great Lakes and will
combine with already sufficient over-water instability to result in
some lake enhanced snow east of Lake Ontario mainly after late
evening. Forecast soundings where lake effect is persistent
overnight indicate at least a 6 hour period (03z-09z) where
inversions lift to 5-7kft with good portion of lake convective layer
in the DGZ. Most model guidance not showing much qpf or snow, so
increased both east of Lake Ontario over the higher terrain. Snow
totals later tonight into Friday morning could reach at least 3
inches, if not even 5 inches locally if more favorable setup for
lake enhanced snow persists longer. This still falls short of CIPS
analogs which would point to low-end advisory amounts. Upper pattern
in those analogs looks a bit too amplified compared to what occurs
tonight though.

Away from the lake enhancement east of Lake Ontario, dry conditions
will prevail tonight into Friday with just a bit more clouds later
tonight through daybreak Friday before skies clear out by afternoon.
Lows tonight will fall back into the teens to low-mid 20s, coolest
inland east of Lake Ontario and warmest across the lake plains.
Highs on Friday will reach the low 30s east of Lake Ontario and into
the mid or even upper 30s elsewhere as warm air advection ramps up
between high departing off east Coast and low pressure system tracking
over south central Canada.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
Dry weather will last through the first half of Friday night under a
longwave upper level ridge. As the ridge pulls away to the east, a
mid level shortwave trough will bring a warm front through the upper
Great Lakes and move through the area late Friday night and through
Saturday morning. With the frontal passage, precip looks to spread
southwest to northeast through the CWA. Forecast thermal profiles
are marginally cold enough to support snow as the precip first
arrives. A quick changeover to rain is expected shortly afterward,
particularly across the lake plains where southerly winds will
result in downslope warming. Gusts of around 45 mph are possible off
the Chautauqua Ridge. Expect at least some snow further inland, but
amounts will be light, up to an inch before the rain moves in.
Temperatures on the Tug Hill will be a bit slower to warm Saturday
morning, allowing for slightly higher accumulations on the order of
an inch or two. Mainly dry weather is expected Saturday afternoon as
the boundary exits to the east and weak surface high pressure works
into the area from the southwest. Lows Friday night will be in the
upper 20s to low 30s. Warm air advection will provide a mild
Saturday, with highs in the mid 40s for most of the area.

High pressure will continue to provide mostly dry conditions
Saturday night with temperatures in the low 30s, but some cloud
cover may linger. Another warm front will approach the region as
this high exits off the New England coast. Precip may start out as
snow Sunday morning, but given the warm overnight temperatures, any
frozen precip will quickly change over to rain. Low chances for rain
showers will linger throughout the day, otherwise it will be warmer
with highs in the mid 40s to lower 50s.

A cold front will cross the region Sunday evening into early Monday
morning. Any leftover rain may change back over to snow with the
frontal passage, but the overall best chances for precip look like
they should be well north and south of the area, associated with the
main low pressure to the north and another developing area of low
pressure well south of the region.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Progressive pattern through the period will support increasingly
mild weather. The relatively fast flow will also lend itself to low
confidence with the details in timing and track of systems.

Monday will be notably chillier than the weekend...as a secondary
cold front will sweep through the region. It will also be breezy to
downright windy...pending which guidance solution verifies. At this
point though...the GFS is the outlier and given its relative poor
performance to 4D VAR packages will throw it out at this time. ECMWF
and Canadian NH preferred.

High pressure moves thorugh the region Monday night and Tuesday.
Very limited lake effect response off Ontario will be possible...
otherwise quiet period.

Complex southern stream system approaches Wednesday and moves
through on Thursday. Question of phasing will come into play. While
operational guidance (ECMWF...Can NH and GFS) is suggesting
unsettled weather...ensembles leaning dry.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Expect mainly dry weather through early evening with VFR conditions.
While conditions will deteriorate somewhat over and east of lake
Ontario with cigs lowering to MVFR levels...VFR conditions should
persist across the western counties.

Expect mainly VFR weather Friday through the first half of Friday
night.

Outlook...

Saturday...VFR/MVFR. A chance of rain or snow showers, becoming all
rain by Saturday afternoon.
Sunday...VFR. Chance of rain showers.
Monday...MVFR. Chance of rain and snow showers.
Tuesday...MVFR to VFR. A chance of snow showers.

&&

.MARINE...
WNW to NW winds will remain elevated over Lake Ontario through this
evening as pressure gradient stays fairly tight between high
pressure to the west and an area of low pressure exiting northern
New England. Thus, Small Craft Advisories (SCA) for Lake Ontario run
through late this afternoon for western zones, and through this
evening for central and eastern zones.

Conditions will remain below SCA criteria overnight and Friday,
before south winds freshen later Friday night bringing the
possibility for the next round of SCA headlines.

Beyond the weekend, those with interests on the lakes should keep
eye on Monday as there looks to be potential for high-end gales from
the west across especially the waters of Lake Ontario.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...None.
MARINE...Small Craft Advisory until 11 PM EST this evening for
         LOZ043>045.

&&

$$

SYNOPSIS...JLA/JM
NEAR TERM...JLA
SHORT TERM...Apffel/PP
LONG TERM...RSH
AVIATION...JLA/JM
MARINE...JLA/JM

NWS BUF Office Area Forecast Discussion