Scientific Forecaster Discussion
fxus61 kaly 241806
Area forecast discussion
National Weather Service Albany New York
206 PM EDT Fri Mar 24 2017
unsettled conditions will arrive this morning and will persist
into the upcoming weekend, with a wintry mix of precipitation
expected. Initially, the warm front will bring a mix of snow,
sleet and freezing rain before transitioning over to rain by the
mid to late afternoon today.
Near term /through tonight/...
a Winter Weather Advisory has been allowed to expire at 2 PM
for the eastern Catskills, Schoharie valley, Mohawk Valley,
greater capital region, northern and central Taconics, as well
as the Berkshires...
A Winter Weather Advisory remains in effect from 6 am to 4
PM today for the southern Adirondack region, Lake George
northern Saratoga region and southern Vermont...
As of 200 PM EDT, the precipitation is continuing to exit the
area allowing for conditions to improve. We did see some large
snow flakes transiting to sleet then freezing rain during the
late morning hours. But this has come to an end so most
locations should see a break in precipitation through the
afternoon (except maybe the far northeastern spots). Therefore
will be letting the Winter Weather Advisory expire at 2 PM for
all of the southern locations. Glen Falls is still reporting up
so plan on letting the northern zones west-southwest continue until 4 PM.
In terms of the forecast, have trended pops back but will likely
trend them back further in the next package given recent trends
in radar. Seems as if the latest few hrrr runs have had a good
handle on the precip. Also updated the hourly temps to better
reflect most recent obs.
the strengthening isentropic lift and steadier
precip shield across the eastern Great Lakes and western New York state
will overspread the region from the west between roughly 8-11 am
this morning. Regional vwp's indicate a low level jet currently
translating NE across central/western New York and PA. As this low
level jet impinges on the region, we expect sufficient
moistening of the sub cloud layer to initiate precipitation,
particularly from around the I-88 and I-90 corridors northward
between roughly 8-11 am this morning.
P-type should initially be snow at its leading edge, before a warm
nose aloft between h750-850 causes sleet to mix in, and eventually
rain/freezing rain. We expect some wet bulb processes to cool the
boundary layer in areas where precipitation occurs, so even though
temps may briefly rise to or slightly above freezing in some areas
prior to precipitation developing, it likely will fall back to
freezing or slightly lower for a period, resulting in the potential
for freezing rain.
The steadiest precipitation and greatest wet bulb processes are
expected to remain mainly north of I-90, with a snow/sleet mix
changing to freezing rain/sleet later this morning into early
afternoon. Warm advection should allow for temps to gradually rise
above freezing this afternoon, but it could take until late
afternoon across portions of the southern Adirondacks and sheltered
valleys of southern VT, and perhaps portions of eastern Berkshire
Colorado. Will have to watch temperatures closely in these areas in case
current winter weather advisories need to be extended later in time.
Snow/sleet accumulations should generally remain light from I-90
south, generally a coating to less than an inch. To the north, a
coating to up to an inch is possible for lower elevations, while 1-2
inches occurs across higher terrain, esp across southern Vermont and the
Ice accretion should generally be a trace to less than one tenth of
an inch, with the greatest amts across portions of the western
Late day highs should reach the mid/upper 30s for northern and
eastern areas, with lower 40s farther south across the Mid Hudson
For tonight, the best forcing should lift north of the region, but
pockets of light rain and drizzle may continue. As winds shift into
the north toward daybreak across northern areas, there could be some
pockets of freezing rain/drizzle developing, and trends will need to
be watched. Low temperatures will mainly be in the 30s.
Short term /Saturday through Monday/...
a very complex forecast including a wide variety of
precipitation types are in the forecast during the short term
period. The complexity of the forecast requires speaking in
general terms as positioning of frontal boundaries relative to
the large ridge of high pressure to the north hold the key to
the forecast. Much of the short term forecast period will have
Saturday through Monday...much of the precipitation types will
be diurnally driven with mainly rain during the daytime hours
and mainly freezing rain and sleet across northern areas during
the overnight hours into early morning hours as indicated by
partial thickness values and BUFKIT model soundings. A frontal
boundary is expected to drop southward into the middle Atlantic
region on Sunday as a wave of low pressure over the Midwest
tracks northeast reaching the eastern Great Lakes by Monday
morning. The best chances for freezing rain appear to be between
around midnight and 10 am both Sunday and Monday. While it is
still too early to pinpoint ice accretion there is certainly the
possibility of a tenth to a third of an inch of ice accretion
totals across the northern half of the forecast area. Fortunately
it does not look like temperatures will be below freezing
during the afternoons which will allow what freezing rain which
accretes to melt in most areas. Highs on Saturday are expected
to be in the upper 30s to mid 50s with highs on Sunday in the
mid 30s to mid 40s and highs on Monday in the upper 30s to
around 50. Lows Saturday night will be in the upper teens to
mid 30s with lows Sunday night in the upper 20s to mid 30s.
Long term /Monday night through Thursday/...
generally cool and unsettled conditions are expected through at
least Tuesday, as another upper level impulse tracks toward the
region from the Southern Plains, producing rain and drizzle. Once
this system lifts north and east of the region, there remains
significant uncertainty regarding the timing of yet another southern
stream impulse approaching. Latest 00z/24 deterministic models and
ensembles suggest there could be a break from the clouds and precip
Wed into Thu, and will therefore lower pops during this period, but
with low confidence. It is possible that a stronger northern stream
impulse produces some snow showers across portions of the region
Wed. Temps will remain below average, with highs Tue mainly in the
lower/mid 40s, if not cooler, with highs Wed-Thu in the mid/upper
40s in valleys and 30s to lower 40s across higher elevations.
Overnight lows will mainly be in the 30s Monday night, with 20s and
lower 30s for Tue-Wed nights.
Aviation /18z Friday through Wednesday/...
precipitation has moved out of the area early this afternoon,
except at gfl where up is still being reported. Current thinking
is that gfl will transition over to plain rain by 20z and this
is the only site that may be affected by additional
precipitation this afternoon. So expect mainly VFR/MVFR
conditions through the afternoon.
For tonight, most of the best forcing will be north of the taf
sites. However, some spotty drizzle may develop. In addition,
low ceilings and some fog could develop as well given the moistening
boundary layer. Expect areas of MVFR to IFR, with worst
conditions expected at kgfl and kpsf. The frontal boundary will
drop south through the area tomorrow as high pressure pushes
south. As the front moves south, it will bring potential for
rain/snow showers to all of the taf sites.
Southerly winds around 10-15 kt with gusts of 20-30 kt will be
possible through the afternoon hours, especially at kalb/kpsf.
Winds will then reduce to 10 kts or less tonight and tomorrow as
high pressure builds south into the area.
Saturday night: moderate operational impact. Chance of rain...sn...fzra...sleet.
Sunday: moderate operational impact. Chance of rain.
Sunday night: high operational impact. Likely rain.
Monday: high operational impact. Definite rain.
Monday night: moderate operational impact. Chance of rain.
Tuesday: moderate operational impact. Chance of rain.
Tuesday night: moderate operational impact. Chance of rain showers...ra.
Wednesday: slight chance of rain showers.
a deep snow pack remains in place across much of eastern New
York and western New England. Unsettled conditions will arrive this
morning and will persist into the upcoming weekend, with a
wintry mix of precipitation expected. Initially, the warm front
will bring a mix of snow, sleet and freezing rain before
transitioning over to rain by the mid to late afternoon today.
there is a potential for several rounds of precipitation today
into the upcoming week, with a mix of rain, freezing rain, snow
and sleet possible. Temperatures look to be warm enough during
the afternoon hours each day that most of the precipitation
should fall in the form of rain before changing over to a wintry
mix at night. While there is still some uncertainty with
precipitation types and amounts, there is the potential for
between three quarters of an inch of rain up to an inch and a
half today through Sunday night. Latest mmefs forecast
indicates a few locations going into action stage by next week.
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
New York...Winter Weather Advisory until 4 PM EDT this afternoon for
Vermont...Winter Weather Advisory until 4 PM EDT this afternoon for