Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 221504
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
1004 AM EST Thu Feb 22 2018

.SYNOPSIS...
Much colder and more seasonable temperatures are expected today
along with some mixed precipitation in the form of mainly snow
and sleet. More unsettled weather is expected Friday and during
the second half of the weekend, including some wintry
precipitation.

&&

.NEAR TERM /THROUGH TONIGHT/...
Winter Weather Advisory issued for Berkshire County until 6 PM
today...

Winter Weather Advisory remains in effect until 6 PM today for
the eastern Catskills, Schoharie County and the Helderbergs...

As of 1004 AM EST...Finally starting to see precipitation reach
the ground in some areas, mainly south and west of the Capital
District at this time. 12Z KALY sounding revealed a significant
dry layer in the low-levels, resulting in virga occurring
initially. Current radar reflectivity depicts this well, with an
absence of echos around the Capital District. Precip will fill
in as the column moistens, but also significant web-bulb effect
will lead to precip starting out as sleet and/or rain
(especially south of Albany), then transitioning to snow as the
column is expected to rapidly cool. Less freezing rain now
mentioned in the Catskills due to less magnitude of warm nose
aloft based on hi-res guidance from this morning. Just a limited
area of southwest Ulster County may have some freezing rain.
Otherwise, just snow/sleet for much of the area with rain/sleet
across southern portions of the mid Hudson Valley changing to
snow later this afternoon.

Expanded the Winter Weather Advisory to include Berkshire
County to the with 2-4 inches of snow expected. Otherwise,
current Advisory for the eastern Catskills, Schoharie County and
the Helderbergs remains with slightly greater snowfall totals of
around 3-5 inches now mentioned. Generally 1-3 inches of snow
forecast outside of the Advisory area, with lesser amounts near
Kingston/Poughkeepsie with rain/sleet initially through this
morning. HRRR/3km NAM indicating decent precip rates this
afternoon when the strongest forcing occurs. So snowfall rates
could approach 1 inch per hours this afternoon, which would
impact travel. Will monitor and issue Special Weather Statements
as needed.

This will be a fast-moving system, with precipitation ending
between 5-7 PM. High pressure over southern Canada will expand
southward somewhat tonight, resulting in the precipitation being
shunted south of the forecast area. Cloud cover may clear
somewhat for areas along and north of I-90, but will likely
increase again toward sunrise Friday ahead of the next system.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
A round of wintry mixed precipitation is possible Friday into
Friday evening. This would include light accumulations of sleet
and freezing rain.

Friday, the high shifts eastward over Nova Scotia while the low
level jet magnitudes increase. This will result in a renewed round
of moisture transport and isentropic lift, with precipitation
becoming likely by the afternoon. We`ll start out the day cold
with early morning temps in the teens and 20s, so some mixed
precipitation is likely especially at the onset. The high is not
in an ideal location to keep cold air locked in place, at least
in the north/south valleys below 1000 feet, so currently do not
expect much in the way of wintry accumulation there, as temps
aloft and at the surface warm enough to support mainly rain as
the p-type. Over the higher elevations of the Catskills and
Adirondacks, thermal profiles support more in the way of a
mixture of sleet and freezing rain for a good portion of the
day. This will especially be true over the Adirondacks where a
fairly deep snow pack still exists, and it has proven very
difficult to scour out the cold air in similar circumstances.
Still considerable uncertainty with respect to how much
precipitation falls as sleet vs freezing rain, but additional
winter weather headlines are a good possibility for the higher
terrain above 1000 feet. As the temps aloft increase from west
to east, the higher terrain of western New England may hold onto
the colder temps longer, so perhaps more sleet or even light
snow compared with freezing rain there.

Low-level winds veer Friday night spelling a gradual end to the
isentropic lift, with weak high pressure expanding in late. A
good deal of low-level moisture will still be around, so could
see a continuation of light spotty showers or drizzle.
Temperatures Friday and Friday night are not expected to budge
much, remaining mainly in the upper 20s to upper 30s. Temps
across the Adirondacks and western New England above 1500 feet
will likely drop back below freezing at night, so could see some
lingering icy issues there.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
The long term period will feature mainly dry weather and slightly
above normal temperatures, with only one main threat for wintry
precipitation during the second half of the weekend.

At upper levels, a ridge will hold steady over Florida and the
eastern Gulf through the first part of the week. This ridge will
eventually dampen and flatten out by mid-week, allowing for a more
zonal flow through the end of the forecast period.

At the surface, high pressure will be in place on Saturday with
temperatures in the 40s to near 50 degrees. By Saturday night, a low
pressure system will be strengthening and lifting across the western
Great Lakes into Quebec. Warm air advection associated with the
system should bring widespread precipitation into our CWA from
southwest to northeast late Saturday night into Sunday. At the
onset, temperatures should be warm enough for rain or a rain/snow
mix in the high terrain. But by Sunday morning, dew points are still
below freezing so with evaporative cooling and potential cold air
damming, precip will transition to a wintry mix from north to south.
A warm front associated with this system will attempt to lift
northward through the area on Sunday as well but the cold air may be
stubborn to mix out north of Albany. This would allow for the wintry
mix to continue into early afternoon.

By 18z Sunday, the 850mb jet strengths to 40-50kts which may help
warm air mix into the boundary layer as the warm sector moves closer
to our CWA. Thus, there is more confidence in the precip type
changing to rain after 18z Sunday but still this is a low confidence
forecast as cold air is often stubborn to scour out. The cold front
should finally move through Sunday night, ending the precipitation
from west to east.

High pressure noses into the Northeast from the Ohio Valley in the
wake of this system which would lead to breezy conditions Monday
with temperatures slightly above normal in the upper 30s to upper
40s. A secondary cold front associated with the 500mb trough axis
should then arrive by 00z Tuesday with colder air in the 20s
following for Monday night. Despite northwest flow setting up for
the mid-week period, temperatures remain seasonable with highs in
the upper 30s to mid 40s and overnight lows in the 20s. Ridging also
sets in mid-week which should keep eastern NY/western New England
mainly dry.

&&

.AVIATION /15Z THURSDAY THROUGH MONDAY/...
Intermittent mixed precipitation is expected to begin at all TAF
sites this morning. There could be a mix of snow, sleet and rain.
After about 15Z, mixed precipitation is expected to become steadier
and ceilings and visibilities will lower from VFR to the MVFR/IFR
levels. KGFL may have VFR bordering on MVFR since much of the
precipitation could track mainly south of KGFL. By this afternoon,
precipitation type should be snow at KGFL and KALB but may remain a
mix at KPSF and KPOU. Precipitation should taper off by 00Z/Fri with
conditions potentially improving towards the end of the TAF period,
especially at KALB and KGFL.

North winds at less than 10 Kt are expected through the TAF period.

Outlook...

Friday Night: Moderate Operational Impact. Chance of SHRA...RA.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: Moderate Operational Impact. Likely RA...SN.
Sunday: High Operational Impact. Definite RA.
Sunday Night: Low Operational Impact. Slight Chance of RA...SN.
Monday: No Operational Impact. NO SIG WX.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.

&&

.HYDROLOGY...
Significant developments with the ice jam along the Mohawk in
Schenectady County and heading into northeast Albany County. The
ice jam became dislodged earlier this morning from Lock 7, Lock
8, Stockade and downstream to Freemans Bridge then through the
Rexford Bridge and impacting Crescent Dam, Cohoes, and
depositing into the Hudson near Troy. Ice and resulting water
continue to move through the Mohawk as please refer to the flood
warnings for additional details. Water levels in these areas
will continue to fluctuate today. Elsewhere, water levels have
remained rather steady or slowly falling at this time.

Snow and wintry mixed precipitation is expected today, with a
quarter to half inch of QPF expected mainly along and south of
I-90. More rounds of precipitation are expected Friday into the
weekend. Current forecasts call for around a quarter to three
quarters of an inch of precipitation during this timeframe,
highest south of I-90. This may result in additional river
rises. Temperatures are expected to average above normal during
this time, but not as warm as we have seen the last two days.

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.

&&

.CLIMATE...
High temperature records were broken in many areas on
Wednesday.

KALB reached 73 degrees at 244 PM EST
KGFL reached 66 degrees at 243 PM EST
KPOU reached 76 degrees at 415 PM EST which broke the all-time
February high temperature.

Wed Feb 21st Previous record highs:
KALB 65F set in 1981
KGFL 65F set in 1981
KPOU 67F set in 1953

All-time February highs:
KALB 74F set Feb. 24, 2017
KGFL 70F set Feb. 25, 2017
KPOU 73F set Feb. 24, 2017

RECORDS FOR KPOU DATE BACK TO 1949... HOWEVER...DATA IS MISSING
FROM JANUARY 1993 - JULY 2000.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Winter Weather Advisory until 6 PM EST this evening for NYZ047-
     051-058-063.
MA...Winter Weather Advisory until 6 PM EST this evening for MAZ001-
     025.
VT...None.

&&

$$
SYNOPSIS...JVM
NEAR TERM...BGM/JPV/JVM
SHORT TERM...BGM/Thompson
LONG TERM...JVM/Speciale
AVIATION...NAS/JVM
HYDROLOGY...BGM/Thompson/JVM
CLIMATE...NWS ALY



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