Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 210011

Area Forecast Discussion
National Weather Service Albany NY
811 PM EDT Tue Mar 20 2018

A storm system organizing over the mid-Atlantic region will
move off the eastern seaboard tonight, allowing for a moderate
to heavy snow for areas mainly south interstate 90 and east of
interstate 87. Behind this storm, dry and cold weather will
continue into the upcoming weekend.


As of 646 pm EDT...Mid and high clouds will continue to
increase from the south and west across the forecast area, as
the next storm system moves closer to the region. The latest
clean longwave IR channel /10.35 micron/ continues to show the
canopy of clouds expanding north and east of the Capital Region.
Temps will not drop off as much tonight.

Previous near term...

The precip shield associated with the storm system is spreading
out across PA through NJ and now moving into Long Island, NY. It
will have a slow northward push, s high pressure lifts away, a
coastal low develops, as well as fairly dry air at the surface
gradually moderating. Dew point depressions across the forecast
area are over 20 degrees attm, so it will take some time for the
column to saturate.

Overnight tonight, temperatures will be coolest north of the
Capital District where cloud cover is less, in the low teens.
Whereas temperatures to the south of the district will only drop
into the mid 20s with overcast skies and precip nearby. Some
snow showers may eek into the far southern extent of the
forecast area by daybreak. Further details regarding the
storm system follow in the short term discussion.


Surface wave developing along the east coast of Virginia this
afternoon is bringing snow to portions of Maryland and southern
Pa. This wave will shift east later today and tonight with
associated precipitation moving east off the east coast and
remaining south of our area. The main mid-to-upper level
dynamics will approach the east coast on Wednesday with another
surface low forecast to develop along the east coast early in
the day. This surface cyclone will develop just east of the
Delmarva peninsula early Wednesday then drift slowly east
northeast becoming vertically stacked with mid-level low
pressure south of Long Island. Strong upper level dynamics will
combine with a band of mid-level frontogenesis and reduced lapse
rates around the north edge of a closed 700 mb cyclone to set
the stage for bands of moderate to heavy snow across southeast
NY Wednesday afternoon into the evening. The main questions for
our area will center around how far north significant snow can
reach into Hudson Valley and southern New England.

Model guidance is coming into better agreement with this storm
and forecast confidence is slowly increasing. Last night`s 00z
NAM appears to be an outlier bringing heavier precipitation
north to the Capital District, although a few SREF members from
the 09z run today are still showing some heavier amounts
reaching as far north as ALB while the GEFS has a few members
with as much as 0.1 to 0.20 inches of QPF at ALB. GEFS spread at
POU is still rather large with values ranging from 0.10 to 1.0
inches and the majority of members clustered around 0.5 inches.
SREF snowfall amounts at POU are mostly clustered between 5 and
10 inches. Finally, the latest ECMWF has come in a bit lighter
and further south with the heavier QPF than many of these
models indicating that heavy snow in our area could be confined
to southern Dutchess and southern Litchfield Counties, and
points southward.

To summarize, a majority of our operational models and ensemble
members continue to indicate that warning criteria snowfall
with amounts from 5 to 10 inches is a good possibility from
Dutchess to Litchfield Counties, however a fairly rapid drop-
off in snow is expected farther north with most likely
accumulations in the Capital District around or less than an
inch Areas north and west of the Capital District will get no
snow. Have edited grids to reflect these trends.

Behind the storm, dry and cold weather will continue for
Thursday, with highs mainly in the 30s and lows in the teens and
20s, along with a partly cloudy sky. An upper low will drop
south across and south of the area on Friday with limited
moisture and scattered snow showers mainly across the higher
terrain west of the Hudson Valley.


The mean longwave trough over the eastern CONUS and the Northeast
will continue in the long term with below normal temperatures.

Friday night into Saturday...The cold pool of the H500 upper level
low drifts south and east of the region.  Short-wave energy in the
northerly flow may focus some isolated snow showers and flurries
especially north of the Capital Region tied to the diurnal heating.
H850 temps remain in the -10C range.  Lows Friday night will be in
the teens to mid 20s, and highs will be in the upper 20s to mid 30s
over the hills and mtns, and upper 30s to lower 40s in the valleys.
These temps will be around 10 degrees or so below normal

Saturday night into Sunday...A large sfc Canadian anticyclone /1040
hPa/ attempts to ridge in from north-central Quebec. A sfc trough
pivots through the region based on the 12Z ECMWF/GFS/GEFS for
isolated snow showers and flurries at night. A few may linger south
and east of the Tri Cities during the late morning and early
afternoon.  Lows will be similar to Fri night, and highs will be a
tad warmer than Saturday by a few degrees.

Sunday night into Tuesday...A high amplitude ridges builds in from
the Southeast through the Great lakes Region and into eastern
Canada.  The H500 ridge folds over into the Northeast and the
Canadian Maritimes early in the week with a big cutoff cyclone off
the East Coast.  Fair and cold/cool weather is likely into Tuesday,
unless the oceanic cyclone backs westward.  Temps moderate slightly,
but will still be below normal with highs possibly reaching the mid
and upper 40s in the valleys on Tuesday, and mid 30s to lower 40s
over the higher terrain.  A cold front may bring some rain and snow
showers into the forecast area Tue night into Wednesday.


High pressure will continue to ridge in from southern Quebec
tonight into tomorrow. Low pressure will move northeast from
near the Delmarva region tonight into tomorrow morning, and then
slowly moves east to northeast well south of Long Island in the
afternoon to early evening.

VFR conditions for all the TAF sites prior to 12Z/WED. The mid
to high clouds continue to thicken and lower from south to north
across eastern NY and western New England. Some light snow may
break out near KPOU between 11Z-14Z/WED. Conditions rapidly
deteriorate at KPOU in the late morning into the afternoon with
light to moderate snow with IFR/LIFR conditions. Some of the
light snow may reach KPSF by 19Z, and expect MVFR to IFR
conditions with perhaps some reductions to LIFR in moderate snow
in the afternoon. Further north towards KALB/KGFL it will take
some time for the cloud bases to lower and the column to
saturate. A PROB30 group was used for KALB from 18Z-00Z/THU with
perhaps MVFR vsbys.

The winds will light from the north to northeast at 4-7 kts
tonight, but will then increase in the late morning to 8-15 kts
with some gusts in the afternoon at 20-25 kts especially from
KALB/KPSF south and east.


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


The Fire Weather season has officially begun across eastern New
York and western New England. Despite this, snow cover is in
place across much of the region, which will mitigate any
potential fire weather hazards for the time being. Additional
snowfall is expected late tonight through Wednesday night which
will continue to prevent issues in the near future as well.

High pressure over southern Canada will continue to allow for cold
temperatures today with a mostly sunny sky.  A storm system
organizing over the mid-Atlantic region will move off the eastern
seaboard for tonight through Wednesday night, allowing for a
moderate to heavy snow for areas south and east of the Capital
Region. Behind this storm, dry and cold weather will continue for
the remainder of the week.


No hydrologic issues are anticipated through the week.

Dry weather will continue through the remainder of the week for
areas north and west of the Capital Region. Meanwhile, southern
and eastern areas will see some snow between late tonight and
Wednesday night, with the heaviest amounts across Dutchess,
Litchfield counties. Total liquid equivalent in these areas
will approach up to an inch. Dry weather is then expected behind
this storm for the remainder of the week and into the weekend.
This snowfall won`t have any immediate impact on area rivers and

A slow diurnal snowmelt is expected over the next several days,
with temperatures above freezing during the day, and below
freezing at night. There will be little impact on the waterways
with minimal, if any, rises.

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.


Astronomical Spring or the Vernal Equinox officially began at
1215 pm EDT.


CT...Winter Storm Warning from 5 AM Wednesday to 8 AM EDT Thursday
     for CTZ001-013.
NY...Winter Weather Advisory from 8 AM Wednesday to 8 AM EDT
     Thursday for NYZ061-063-064.
     Winter Storm Warning from 5 AM Wednesday to 8 AM EDT Thursday
     for NYZ065-066.
MA...Winter Weather Advisory from 8 AM Wednesday to 8 AM EDT
     Thursday for MAZ025.


LONG TERM...Wasula
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