Albany, NY WFO Forecast Discussion

Forecast Discussion for ALY NWS Office
000
FXUS61 KALY 221143
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
643 AM EST Tue Jan 22 2019

.SYNOPSIS...
After a very cold start to the day, mostly sunny and dry
weather is expected today, with temperatures not as frigid for this
afternoon.  Clouds will increase tonight, with temperatures
generally holding fairly steady.  A light wintry mix changing to
rain is expected for tomorrow into tomorrow night with much milder
temperatures, with the precipitation perhaps changing back to snow
before ending on Thursday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 643 AM EST...1040 hpa high pressure area is located over
western and central PA and continues to slowly slide eastward.
IR satellite imagery shows mainly clear skies over the area.
There are a few lake effect clouds reaching into southern
Herkimer County, although the bulk of the lake effect clouds
extends westward across central and western New York. The
pressure gradient is finally showing signs of relaxing, as winds
are now light to calm at nearly all reporting sites.

With the deep snowpack, clear skies and diminishing winds,
early morning temperatures are very cold. NYS Mesonet is showing
some locations in the Adirondacks as cold as -23 F. Even parts
of the upper Hudson Valley are very cold, as Schuylerville is
down to -21 F and Glens Falls is -15. With a light breeze still
in place in a few spots, wind chill values continue to be 10 to
30 below zero across the region, so anyone venturing out early
this morning is encouraged to bundle up, as frostbite will
continue to be a concern.

After the cold start, temperatures should be warming up today as
upper level heights starts to rise. Although it will be
noticeably warmer than yesterday, it will still be quite cold,
with highs mainly in the teens (perhaps a few low 20s for far
southern areas). With the high pressure areas sliding eastward
through the day, skies will continue to be mainly sunny and
winds will be fairly light.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
As the high pressure area starts to depart, a light southerly
flow will start to develop for this evening into tonight, as
high clouds will start to increase. Temps may initially fall a
few degrees this evening, but will then start to level off and
may even start to rise for later tonight thanks to the
increasing southerly flow and more clouds starting to arrive.
Some light snow may arrive into the western Adirondacks towards
daybreak, otherwise, it will be dry through the overnight hours.

Low pressure will be lifting across the Great Lakes and into
Ontario on Wednesday. Ahead of this system, broad south to
southwest flow at low to mid levels will allow for warm air
advection/isentropic lift. The southwest low level jet will be
increasing to 50+ knots by late in the day, allowing for light
precip to spread into the area from southwest to northeast.
During the morning hours, precip may be limited to far
northwestern areas and will be primarily be snow or snow/sleet,
where a few inches will accumulate across the western and
central Adirondacks. However, by afternoon, precip will be
spreading across the rest of the area. P-type will be transiting
to mainly rain or freezing rain by later in the day, depending
on surface temps (although some sleet may linger across the
Adirondacks as well). Valley areas should primarily be changing
to rain, as the southerly flow allow temps to rise. However,
some northern and sheltered high terrain areas will struggle to
rise above freezing, as the low- level cold air remains trapped,
especially due to the snowpack in place. Some freezing rain may
even occur for areas where the surface temp is just above
freezing, as very cold ground temps could still allow for precip
to freeze on contact as well.

Temps will continue to rise into Wednesday night through the
30s, so most areas should be seeing just a steady cold rain for
Wednesday night (a few isolated pockets of sleet/freezing rain
may continue across the Adirondacks). Temps may even spike near
40 across far southern areas by late Wednesday night ahead of
the advancing cold front.

The storm`s cold front should cross the area on Thursday
morning, although the front will slow down as a wave of low
pressure develops along the boundary. This may allow for a
period of steady precip to continue into the day, mainly the
morning through the mid afternoon. As colder air, both at the
surface and aloft, surges into the region from the west, a
changeover back to snow is possible for western and high terrain
areas by late Thursday morning into Thursday afternoon. It is
still unclear how much precip will be left to occur before temps
cool enough, but a light accumulation is possible for high
terrain areas by precip ends. High temps in the mid 30s to low
40s will occur early in they day before temps fall into the mid
20s to mid 30s for late in the day.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Anomalously strong upper low with sub-490 dam heights at 500 mb will
be located over Hudson Bay to start the period. It will drift
southward toward into Ontario/Quebec by the weekend. Disturbances
will rotate around this low during the period, providing periodic
chances for snowfall. Given the source region for these disturbances
is Continental Polar from Canada, expect any snowfall to remain
light and preferentially located over the higher terrain, especially
over the southern Adirondacks where a lake effect/enhancement will
occur when flow trajectories sufficiently align.

After a mainly dry Thursday night in the wake of the midweek frontal
wave, the first disturbance is likely to generate high terrain/lake
effect snow showers on Friday. Behind this disturbance, Friday night
into Saturday night will likely be the coldest portion of the long
term as H850 temps will fall to the -15 to -20C range, 1-2SD below
normal. It appears the best chance for accumulating snow outside of
the high terrain/lake effect zones will be toward the end of the
period (Sunday/Monday) as stronger warm advection ahead of a sharper
shortwave trough is indicated by model consensus. There is still
considerable uncertainty toward the end of the long term period,
however.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
A narrow ridge of high pressure will cross the region during the TAF
period, resulting in a continuation of VFR conditions. Winds will
also diminish and temperatures will not be quite as cold during the
day today as we have seen recently. Skies will be mainly clear
aside from some increasing high cirrus this afternoon and evening.
Clouds will continue to thicken and lower late tonight but remain
around 10 kft.

West to northwest winds will continue to diminish today, 5 to 10 kt
at KALB/KPSF early, becoming light and variable. Winds will increase
out of the south at 5 to 10 kt at KALB late in the TAF period. LLWS
conditions are possible after 06Z/Wed as winds aloft increase.

Outlook...

Wednesday Night: High Operational Impact. Definite RA.
Thursday: High Operational Impact. Definite SHRA...SHSN...RA...SN.
Thursday Night: Low Operational Impact. Slight Chance of SHSN.
Friday: Low Operational Impact. Slight Chance of SHSN.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: Low Operational Impact. Slight Chance of SHSN.
Sunday: Moderate Operational Impact. Chance of SHSN.

&&

.HYDROLOGY...
Continued cold temperatures today into tonight will continue to
allow for river and lake ice to thicken and strengthen.

The next storm system will arrive late tonight into Wednesday.
Initially, precip will begin as snow or mixed precip before
changing to rain over most of the region by Wednesday night.
The precip may also change back to snow before ending on
Thursday.

Total precipitation amounts are still somewhat uncertain,
although most areas should see around an inch of liquid
equivalent. There is the potential for some high terrain areas
of western New England to see as much as two inches. In
addition, milder temperatures above freezing are expected,
although these temperatures may be rather brief (generally only
18-24 hours at most).

For most of the area, much of the precipitation will be
absorbed by the snowpack on the ground, however, some river
rises are possible, especially for southeastern parts of the
area. Some minor river flooding cannot be ruled out, mainly for
the Housatonic and Hoosic basins. Some isolated ice jam issues
are possible as well, although the limited amounts of total runoff
should prevent this from being a major concern.

Mainly dry weather and colder is expected for Friday into the
weekend and any precip during this time would be scattered snow
showers. This will allow any rivers to slowly recede.

For details on specific area rivers and lakes, including 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...Wind Chill Advisory until 7 AM EST this morning for CTZ001-013.
NY...Wind Chill Warning until 7 AM EST this morning for NYZ032-033-
     038>043-047-048-051-054-058-061-063-082>084.
     Wind Chill Advisory until 7 AM EST this morning for NYZ049-050-
     052-053-059-060-064>066.
MA...Wind Chill Warning until 7 AM EST this morning for MAZ001-025.
VT...Wind Chill Warning until 7 AM EST this morning for VTZ013-014.
     Wind Chill Advisory until 7 AM EST this morning for VTZ015.

&&

$$
SYNOPSIS...Frugis
NEAR TERM...Frugis
SHORT TERM...Frugis
LONG TERM...Thompson
AVIATION...Thompson
HYDROLOGY...Frugis

NWS ALY Office Area Forecast Discussion