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fxus61 kaly 212340 
afdaly

Area forecast discussion
National Weather Service Albany New York
640 PM EST Tue Feb 21 2017

Synopsis...
a weak disturbance approaching from the eastern Great Lakes will
move across the area tonight, bringing chances for light rain or
light freezing rain in some spots. Mild conditions with well above
normal temperatures are then expected to build in for the remainder
of the week.

&&

Near term /until 6 am Wednesday morning/...
as of 630 PM EST...not much change to ongoing forecast as line
of showers continues to advance east and will arrive around
03-07z timeframe for the region.

Prev disc...Freezing Rain Advisory in effect for portions of
the southern Adirondacks, Lake George Saratoga region, central
Mohawk Valley, western Schenectady County, northern Taconics,
southern Vermont and the Berkshires from 8 PM this evening to 6
am Wednesday.

Temperatures have warmed into the mid 30s to mid 40s across the
region this afternoon, although a very dry air mass remains in place
with surface dewpoints in the teens to lower 20s. So when light
precip arrives this evening/overnight, wet bulb cooling is expected
and temperatures should drop into the lower to mid 30s.

An upper level disturbance and jet streak quickly moving across the
region this evening and overnight will result in some light
precipitation developing. Output from hi-res guidance such as the
hrrr and the 4km NCEP WRF continues to indicate greater coverage of
precip than the lower resolution models such as the NAM/GFS. So will
continue to mention 40-60 pops for much of the area with scattered to
likely coverage.

Temperatures expected to cool to around or slightly below freezing
for portions of the area, mainly north of and outside of the capital
district. Even though quantitative precipitation forecast will be light, we have issued a Freezing
Rain Advisory for a trace to 0.05 inches of ice. Even trace amounts
can cause a driving/walking hazard on untreated surfaces, thus
opting for the advisory.

Light rain will occur for areas outside the advisory, with precip
generally ending before sunrise Wednesday as the disturbance quickly
moves eastward. A few sprinkles will be possible early Wednesday
morning.

Lows tonight will generally be in the upper 20s to mid 30s with
temperatures rising a few degrees towards sunrise Wednesday.

&&

Short term /6 am Wednesday morning through Thursday night/...
the main story for the short term period of the forecast will be
very mild temperatures. Milder air will start to build in on
Wednesday, with temps aloft warming to around +5c to +6c. Mixing
does not look very favorable to reach full warming potential though.
Some breaks of sunshine are expected to develop by late morning and
afternoon, so will mention high temps in the mid 40s to lower 50s.
Relatively cooler locations will be north of the capital district,
but still quite mild for late February.

Mild temps continue Wednesday night, with the entire area expected
to remain above freezing with lows mainly in the mid to upper 30s
due to a light southerly flow. A few showers may brush portions of
the western/southern Adirondacks with a disturbance approaching from
the Great Lakes. Patchy fog should develop across areas with
snow still on the ground.

Zonal flow aloft to persist on Thursday, with even warmer conditions
expected. Forecast soundings indicating better mixing potential,
although degree of cloud cover is somewhat uncertain. At this time
will mention partly sunny skies for most of the area. Highs could
approach or exceed 60 degrees in some valley locations depending on
how much sunshine can occur. The record high for Albany Thursday is
62 degrees set back in 1984. Cooler lower/mid 50s expected over the
Adirondacks and southern greens with more cloud cover.

A short wave ridge of high pressure will briefly build in Thursday
evening, but a warm front approaching form the Midwest and Ohio
Valley will bring increasing chances for showers late Thursday night
into early Friday morning. Mild temps continue, so plain rain
expected for p-type.

&&

Long term /Friday through Tuesday/...
as mentioned in previous discussions, an active period of weather
is expected through this last weekend of February.

Highly energetic jet interacting with increasing baroclinic zone
over the center of the nation will aid in the development and
strengthening surface low across the mid and upper Mississippi River
valley and through the Great Lakes region. Downstream impacts will
be a warm front lifting north with clouds and the chance for light
precipitation to develop through Friday into Friday evening. As low
level jet increases to 50kts or greater, this will assist with
advecting warm and moist air over a snowpack. This should result in
patchy fog and the chance for drizzle with little diurnal
temperature drop expected.

The main impact day still remains on Saturday. Gefs precipitable water anomalies
remain 2-3 Standard deviations above normal with v-component of the
925-850mb winds approaching 5 Standard deviations above normal. This
is ahead of a digging trough that evolves toward a negative tilted
pattern. Given a highly dynamic pattern, expectations are for
periods of moderate to period of heavy rain, snow melt (where recent
nohrsc suggests 10-12" of water equivalent was present in the
mountains) and the chance for thunderstorms as showalter values drop
to around 0c from the global model consensus.

Frontal passage occurs during the early evening Saturday as h850
temps drop from near +10c on 18z/Sat to -10c 18z/sun. This will set
the stage for lake effect snow to develop downwind of Lake Ontario
for portions of the dacks and western Mohawk Valley. Furthermore,
strong gusty winds are expected due to tight pressure gradient and
around 40kts at h850.

Another fast moving clipper type system is expected to race across
the region for early next week. However, moisture profiles appear
disconnected as chances for precipitation appear slight chance at
this time.

Temperatures will be on a unique swing from well above normal to
near or below normal through the weekend.

&&

Aviation /00z Wednesday through Sunday/...
VFR expected into the evening hours tonight as mid and high
clouds increase and gradually lower throughout the evening. A
weak system has the potential to bring some light/MVFR rain
showers after 03z tonight, with a chance for some freezing rain in the
high terrain, mainly at kpsf. There is also potential for IFR
conditions to develop prior to dawn with moisture becoming
trapped beneath a lowering inversion north of kpou. Have
continued the previous forecast of prevailing IFR at kgfl/kpsf
after 09z for the time being with gradual improvement back to
MVFR towards the end of taf period.

Southerly winds are 5 to 10 kts with some gusts up to 20 kts
for kalb. Winds will then slacken overnight tonight through
Wednesday.

Outlook...

Wednesday night: low operational impact. Patchy fog.
Thursday: low operational impact. Slight chance of rain showers.
Thursday night: moderate operational impact. Chance of rain showers.
Friday: moderate operational impact. Chance of rain showers...dz.
Friday night: moderate operational impact. Slight chance of rain showers...dz...fg.
Saturday: high operational impact. Definite rain showers...tsra.
Saturday night: moderate operational impact. Chance of rain showers...shsn.
Sunday: no operational impact. No sig weather.

&&

Hydrology...
no widespread Hydro problems are expected through the rest of the
work week, with just light precipitation forecast and overnight
temperatures falling into the upper 20s and 30s the next few nights.

However, mild temperatures that will be well above normal, are
expected for later this week. This will cause snowmelt and
subsequent runoff. Also, a strong storm system may bring a period of
moderate to heavy rainfall on Saturday. The meteorological model
ensemble river forecasts /mmefs/ continue to suggest significant
river rises will occur, with flooding possible Saturday into Sunday
due to the combination of snow melt and locally heavy rain.

At this time, at least minor flooding appears likely for a few to
several points along main Stem river. Depending on the degree of
snow melt, flooding could reach moderate levels in some locations.
We will have more specific information as the weekend draws
nearer.

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...none.
New York...Freezing Rain Advisory until 6 am EST Wednesday for nyz033-
039>043-048-054-082>084.
Massachusetts...Freezing Rain Advisory until 6 am EST Wednesday for maz001-025.
Vermont...Freezing Rain Advisory until 6 am EST Wednesday for vtz013>015.

&&

$$
Synopsis...11/jpv
near term...bgm/jpv

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