Henrietta, New York 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

415
FXUS61 KBUF 211945
AFDBUF

Area Forecast Discussion
National Weather Service Buffalo NY
245 PM EST Thu Nov 21 2024

.SYNOPSIS...
Transition of energy between two surface low pressure systems
this afternoon, will support the surface low over the New
England coastline to retrograde back into the Great Lakes
tonight and Friday before returning to the New England coastline
by Friday night, resulting in cold rain and wet snow. The lower
elevations will see little to no snow accumulation, while the
higher terrain will see a few inches of slushy snow
accumulations this evening through Friday. Lake effect showers
will continue into Sunday morning before petering out late in
the afternoon. However the break in dry weather won`t last long
as the next system will be approaching our doorstep early next
week.

&&

.NEAR TERM /THROUGH FRIDAY/...
Complicated surface pattern this afternoon supporting the lingering
synoptic lower elevation rain/higher elevation snow and across both
western New York and the North Country. Two area of precipitation
are being depicted by radar, with a few scattered showers across far
northwestern Niagara county, some snow showers across the higher
terrain of Allegany and Cattaraugus counties and steady rain
continuing across the North Country. Overall these areas of
precipitation are being supported by the transfer of energy from the
surface low centered over northern Lake Michigan, which is settling
southward and the strengthening low off the New Jersey coastline.

This afternoon and tonight, with the transfer of energy between
these two systems, an abundance of moisture will continue to advect
into the region, causing the rain across the North County to expand
westward into the Genesee Valley this afternoon and into western New
York by this evening. While temperatures across the lower terrain
remain above freezing this afternoon, rain will likely be the main
precipitation type, however some locations across the higher terrain
will be below freezing supporting some wet snow to mix in. Any snow
accumulations this afternoon will remain marginal.

Tonight, while the surface low over northern Michigan currently
drops south into the Ohio Valley, the surface low off the coast of
New Jersey will deepen and retrograde northwest into the Catskills,
continuing widespread lower elevation rain and high terrain snow.
Forecast thermal profiles will be ever-changing with time due to
milder air from the east being pulled into the low, supporting a
difficult higher terrain snow forecast. While temperature will cause
a difficult precipitation type forecast, moisture will be plentiful
due to moisture being advected in to the area from the Atlantic and
support a large precipitation shield. This all being said, lower
elevations will likely remain as rain with some possible wet snow
early tonight, and despite the snow little to no accumulation is
expected. The one caveat that would support a slushy coating would
be if precipitation rates are high enough keeping temperatures on the
cooler side due to evaporative cooling. The colder air however will
remain across the higher terrain (above 1500 ft) where the surface
temperatures will be in the lower 30s. Given the deepening
retrograding (westward movement) of the surface low, this will
support favorable set up for mesoscale forcing to produce bands of
heavier enhanced precipitation from the Finger Lakes into the
Southern Tier of western New York. Snowfall amounts will range
between 2 to 7 inches at elevations above 1500 ft. The snowfall
range is set a bit larger due to the complex nature of the surface
low track and thermal profiles.

Winter Weather Advisories have been issued for the Wyoming Hills,
higher terrain of the western Southern Tier and Tug Hill tonight
through Friday morning.

The surface low will then move southward into eastern Pennsylvania
Friday, causing dry air to filter into the forecast area and
precipitation to begin to dwindle down from east to west. However,
due to northwest winds supporting orographic lift and limited lake
enhancement western New York, especially the western Southern Tier
showers will continue. Temperatures will gradually modulate Friday
supporting precipitation to change back over to rain.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY NIGHT/...
P-type might become a bit of a challenge by Friday night as drier
air begins to wrap in around the departing low. While precipitation
will `likely` continue in the liquid form below 1000 feet, above
that elevation there will be a transition gradually over to snow.
That said...there is one caveat, as was mentioned drier air moving
into the mid-levels may produce just drizzle. This is indicated in
BUFKIT sounding profiles with a pronounced dry layer in the DGZ (-10
to -20 layer). Additionally...the airmass circulating in across the
Lower Lakes is not all that cold, with 850T`s only down to -3C to
-4C) aloft. Therefore...have limited snow accumulations to under an
inch Friday night into Saturday morning across the S. Tier. The
higher terrain of the Tug/Western Dacks it will be matter of how
much precipitation lingers as the low pulls further away overnight.
Even so...we are only looking at nuisance accumulations of an inch
or less there too.

As the low moves further out to sea Saturday it will then draw
Atlantic moisture back eastward across the forecast area. A cool WNW
flow (850H temps still around -2C/-3C) with the increase in moisture
will lead to a reinvigorated lake response causing showers to expand
across much of the area. The main lake enhanced/upslope areas east
and southeast of the lakes will see the most activity, though the
warmer daytime temps will `likely` support rain as the dominant p-
type for all locales. Temps cooling overnight Saturday night may
support some wet snow across the higher terrain areas.

Sunday....a mid-level shortwave dropping southeast through the
region is advertised to bring a brief shot of colder air (850H temps
-4 to -8C) to the region. This will likely be just enough to
maintain at least a chance for showers (rain/wet snow higher
terrain) east/southeast of the lakes through the day. However, drier
air again filtering into the region should limit the lake effect
potential despite the injection of colder air.

Sunday night...continued drier air working into the region and then
warming mid-levels will slowly bring about an end to any lake
induced showers by Monday morning.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Surface high pressure will briefly ridge across the region Monday
morning, resulting in mainly fair and warm weather for the day.
After this, a mid level trough digging across the upper Great Lakes
will lead to surface low pressure developing and tracking across the
eastern Great Lakes Monday night into Tuesday. This will bring a
shot of widespread rain showers with modest rainfall amounts around
a quarter inch. It will also become windy and cooler Tuesday in the
wake of the passing surface low.

Consensus 850mb temperatures drop down to around -8C by late Tuesday
night, with a fairly moist cyclonic flow aloft. This will support
some lake effect precipitation, with it cold enough for some of this
to be snow. Westerly winds will direct most of the lake effect and
upslope enhanced precipitation across the typical snow belts east of
the lakes Tuesday night and Wednesday. Accumulating snows are
likely, with advisory level amounts (greater than 4 inches) possible
but far from a certainty. Due to the marginally cold air mass,
greater accumulations would be more likely across higher terrain
such as the Chautauqua Ridge and Tug Hill.

A more zonal flow aloft develops by Thursday, with some models
developing a wave of low pressure and tracking it to our south. This
possible system in addition to lingering lake effect may produce
some rain or snow showers.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
Complicated surface pattern this afternoon supporting the lingering
synoptic lower elevation rain/higher elevation snow and across both
western New York and the North Country. Two area of precipitation
are being depicted by radar, with a few scattered showers across far
northwestern Niagara county, some snow showers across the higher
terrain of Allegany and Cattaraugus counties and steady rain
continuing across the North Country. Conditions within the showers
are supporting MVFR conditions, especially for KART and KJHW, with
all other TAF sites supporting low end VFR.

The initial parent low over the central Great Lakes will give way to
secondary cyclogenesis off the southern New England coast this
afternoon, supporting deep moisture to wrap back into the area from
the east, with rain spreading back westward along with CIGS lowering
to MVFR/IFR. Rain will stay the main precip type for lower
elevations, but some wet snow may mix in across higher terrain.

MFR and IFR conditions will continue tonight due to the deepening
retrograding low pressure system over the Catskills. A wide swath of
precipitation with some mesoscale banding will continue to support
widespread rain and higher elevation snow overnight.

Outlook...

Friday...Widespread IFR with periods of rain and higher elevation
wet snow.
Saturday...MVFR/IFR with a few rain and wet snow showers.
Sunday...VFR/MVFR with a chance of a rain or snow shower.
Monday and Tuesday...MVFR/IFR with rain and snow showers possible.

&&

.MARINE...
Weak to calm winds this afternoon will shift north/northwesterly and
ramp up on the backside of a deepening retrograding coastal low
pressure system. Widespread small craft advisory conditions will
begin this evening and last into Friday night.

As the low moves south and then southeast into Pennsylvania and back
to the New England coastline Friday night, the pressure gradient
will weaken supporting a drop in winds and waves.

&&

.BUF WATCHES/WARNINGS/ADVISORIES...
NY...Winter Weather Advisory from 6 PM this evening to noon EST
     Friday for NYZ008-012-019>021.
MARINE...Small Craft Advisory from 7 AM to 7 PM EST Friday for LEZ020.
         Small Craft Advisory from 10 PM this evening to 1 AM EST
         Saturday for LEZ040.
         Small Craft Advisory from 10 PM this evening to 7 PM EST
         Friday for LEZ041.
         Small Craft Advisory from 10 PM this evening to 7 PM
         EST Friday for LOZ043-044.
         Small Craft Advisory from 4 AM to 7 PM EST Friday for
         LOZ030.
         Small Craft Advisory from 10 PM this evening to 10 PM EST
         Friday for LOZ042.
         Small Craft Advisory from 10 PM this evening to 4 PM EST
         Friday for LOZ045.
         Small Craft Advisory from 4 AM to 1 PM EST Friday for
         SLZ022-024.

&&

$$

SYNOPSIS...EAJ
NEAR TERM...EAJ
SHORT TERM...AR
LONG TERM...Apffel
AVIATION...EAJ
MARINE...EAJ/RSH