Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kaly 212323 
afdaly

Area forecast discussion
National Weather Service Albany New York
623 PM EST Thu Nov 21 2019

Synopsis...
high pressure will move east of the region tonight.
A warm front will bring a light rain and snow shower mix overnight
with a fast moving low pressure system. The cold front will move
through tomorrow with isolated to scattered rain to snow showers and
blustery conditions. High pressure will bring fair and cold
conditions to open the weekend before a complex storm system brings
potentially a wintry mix of precipitation types Saturday night into
Sunday.

&&

Near term /until 6 am Friday morning/...
clouds thickening and lowering and showers in western New York moving
east. Just minor adjustments to sky cover, temperatures and
timing of showers. Previous afd has a few more details and is
below...

High pressure at the sfc and aloft will slowly move east of the
region tonight. The mid and upper level ridge axis moves off
the New England coast after 06z/Fri. Mid and upper level heights
fall, as a warm front lifts north and east across the region.

The weak warm advection or isentropic lift on the 290k surfaces
will allow for some light snow showers to impact the western
Mohawk Valley north and east into the southern Adirondacks. The
best synoptic forcing moves into the North County. A few ice
pellets may mix in but we are expecting a brief spell of snow
transitioning to light rain showers, as temps will fall off
quickly prior to midnight, but then rise after midnight or
steady. The 3-km hrrr and namnest support a quick snow to rain
transition. Lows should be early in the mid to upper 30s in the
lower elevations and lower to mid 30s over the higher terrain.
The winds will increase out of the south to southwest. Any snow
accumulations especially over the higher terrain of the
Adirondacks will be in the coating to less than a half an inch
range.

C&&

Short term /6 am Friday morning through Saturday night/...
tomorrow...a trough of low pressure lifts poleward across
south-central Quebec. A rather strong cold front will sweep
across the region in the late morning through the early/mid PM.
Temps should rise to normal to above normal levels. However,
temps may fall quickly in the wake of the front. Strong low-
level cold advection will occur and the latest BUFKIT momentum
Transfer profiles do show the possibility of mixing 35 kts or
so from 2-2.5 kft above ground level. If we mix a little higher a few 40 kt
gusts are possible, but this should be briefly and mainly with
the frontal passage, and an Special Weather Statement may be able to handle it. The
stronger winds should be from the Mohawk Valley, capital region,
Berkshires northward. The h850 winds will increase to 35-45 kts
or so by the early to mid PM.

A few heavier snow showers or an isolated squall is possible
over the western Adirondacks where better low-level moisture and
vorticity advection is in place with steepening low and mid-
level lapse rates. Most the region will see isolated to
scattered rain to rain/snow showers with the frontal passage. It
will become blustery and cold. The better convergence with the
boundary is from the I-90 Corridor North. Highs will be in the
mid 40s to a few spotty 50f readings in the Mid Hudson valley
and northwest CT, except across the southern Adirondacks and southern
greens where upper 30s to lower 40s are possible. Temps will
fall into the 30s west of the Hudson River valley. It will be
blustery with west to northwest of 15 to 25 mph. Some scattered
light dustings to a few tenths of an inch of snow are possible
especially over the Adirondacks.

Friday night...a brief connection with lake effect snow showers
and flurries may impact the northern Catskills, and western
Mohawk Valley early in the evening. Otherwise, clearing skies
and diminishing winds will occur, as high pressure builds in
from the Ohio Valley with cold and dry conditions with lows in the
20s with a teens over the southern Adirondacks and southern
greens.

Saturday...the weekend opens with fair and cold weather with
high pressure over the upper mid Atlantic states and northeast.
Max temps will be below normal by at least 5 degrees. Sunshine
will give way to increasing mid and high clouds late. Highs
will be in the upper 30s to lower 40s in the lower elevations,
and upper 20s to mid 30s over the hills and mtns.

Saturday night...a southern stream system lifts northeast
towards the forecast area from the mid Atlantic states. The
region will see clouds thicken and lower with low-level
isentropic lift increasing from the southern stream system, and
a northern stream short-wave will be approaching from the Great
Lakes region. The CMC/ec/GFS/ensembles show an increase of
thermal advection for initially some snow perhaps transitioning
to sleet/freezing rain well after midnight south of the capital
region. Some light accumulations are possible. This forecast may
change based on the thermal profiles, track and evolution of the
system. The 12z NAM keeps this system unphased with little
impact. Overall, some snow to start perhaps transitioning to a
wintry mix. We will keep mention in the severe weather potential statement. Lows will be in the
20s to lower 30s.

&&



Long term /Sunday through Thursday/...
at the start of the long term period, low pressure will be quickly
strengthening off the mid Atlantic coast as it lifts northeast to
the south of New England. Meanwhile, the primary low pressure area
over western New York will be weakening, as the offshore storm takes
over. With our area on the northwest side of the storm, there looks
to a steady shield of precip that occurs through much of the day.
Precip type will likely be tied to elevation and precip intensity.
12z GFS BUFKIT soundings show temps warming up just enough in the
boundary layer for the capital region and other valley areas to the
south and east for precip to be mainly rain through the day as
surface temps warm into the mid to upper 30s. However, the profile
may be more isothermal near 0 c across the higher terrain, as well
as areas north/west of the capital region, which could allow for wet
snow (perhaps some pockets of sleet) for those areas. Will allow
for some light snow accumulation on Sunday for areas outside the
immediate capital region, Mid Hudson valley, and northwest CT, but will
keep amounts of generally just a coating to a few inches, as gefs
suggest quantitative precipitation forecast amounts will only be a few tenths of an inch. Most
areas should be done seeing precip by late afternoon or early
evening, with precip exiting western New England last. Most areas
look dry for Sunday night, although some lake enhanced flurries or
light snow showers are possible for the western Adirondacks, with
temps falling into the 20s across most of the area.

Behind this departing storm, brief shortwave ridging and surface
high pressure will pass across the area for Monday into Tuesday.
This should allow for dry conditions with a partly to mostly clear
sky. Highs on Monday will be in the lower to mid 40s for valley
areas, with highs a little milder on Tuesday, generally in the mid
to upper 40s.

Warm advection will be underway for Tuesday night, so temps may not
fall off too much with clouds increasing. A few showers are possible
across the Adirondacks by late in the night, otherwise, it looks dry
with temps generally remaining above freezing.

Strong low pressure will be passing across the Great Lakes and into
southern Canada on Wednesday. The storm's cold front should be
moving through area for Wednesday with a band of rain showers. Temps
look to warm up plenty ahead of the front, both at the surface and
aloft, so any precip should be just plain rain. Highs should be
well into the 40s for most locations.

Behind the front, temps will cool off and some lingering wrap around
showery precip will occur for Wednesday night into Thursday
(thanksgiving day) as the upper level trough cuts off and slowly
moves across the area. Precip looks mainly rain showers for valley
areas due to surface temps in the mid 30s to low 40s, but high
terrain areas could be seeing some snow shower activity with temps
in the low 30s.

&&

Aviation /23z Thursday through Tuesday/...
localized fog over gfl will mix out as higher clouds thicken
and showers move into the region. Then VFR conditions will
prevail at the taf sites this evening. Clouds with ceilings at
or above 5000 feet will increase ahead of a warm front this
evening, then scattered light showers will develop overnight at
gfl/alb/psf. A little freezing rain is possible with these
showers at gfl as temperatures will be near freezing. Ceilings
and visibilities may briefly lower to MVFR in showers after
midnight tonight and until around 14z-15z. VFR conditions will
prevail on Friday as a cold front moves east of the area.

Gusty westerly winds will develop along and behind the front
with speeds increasing to 15 to 25 kts along with a few higher
gusts into the afternoon.

Outlook...

Friday night: low operational impact. Breezy no sig weather.
Saturday: no operational impact. No sig weather.
Saturday night: moderate operational impact. Likely rain...sn.
Sunday: high operational impact. Likely rain.
Sunday night: low operational impact. Slight chance of rain showers...shsn.
Monday to tuesday: no operational impact. No sig weather.

&&

Fire weather...
the fire weather season ends today. The issuance of this
product will resume in Spring 2020.

&&

Hydrology...
no widespread problems are expected on the main Stem rivers and
within the aly hsa the next several days into the middle of
next week.

The precipitation from the system tonight into tomorrow will
have little effect on the aly hsa waterways.

A complex storm system may bring some rain, snow and or a wintry
mix Saturday night into Sunday with light to moderate amounts of
qpf, but their is still uncertainty in the track, evolution and
the amount of quantitative precipitation forecast with this system. The bottom line, there will
be minimal rises on the waterways.

For details on specific area rivers and lakes, including latest
observed and forecast river stages and lake elevations, please
visit the advanced hydrologic prediction service /ahps/ graphs
on our website.

&&

Aly watches/warnings/advisories...
CT...none.
New York...none.
Massachusetts...none.
Vermont...none.

&&

$$
Synopsis...wasula
near term...NAS/wasula
short term...wasula

National Weather Service Glossary of Abbreviations