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Area forecast discussion 
National Weather Service Albany New York
408 am EST Friday Feb 12 2016

Synopsis...
a weak high pressure will build across the region today
followed by an Arctic cold front Friday night with snow showers and
some snow squalls. In the wake of this cold front...windy and
bitterly cold temperatures will remain across the region throughout
the weekend.

&&

Near term /until 6 PM this Evening/...
Lake effect snow showers will be confined across our western
areas...especially across the western Adirondacks during the daytime
hours. A west southwesterly to southwesterly wind upstream of a
small amplitude ridge of high pressure in conjunction with a
westerly flow on the southern edge of a southeastward moving upper
level low pressure system will Orient the bands of snow showers from
SW to NE. Slight chance probability of precipitation are reflected across far northern
Herkimer and Hamilton counties that best reflect the orientation
of the wind field and snow bands set up. Otherwise...mostly clear
skies for the rest of the region. Clouds will build across the
entire region from west to east as we go into the evening hours
ahead of our next weather system.

High temperatures during the day on Friday will remain well below
average with highs ranging from the upper teens in the high terrain
to lower and middle 20s for the rest of the region.



&&

Short term /6 PM this evening through Sunday night/...
wind chill warnings in effect for Saturday-Sunday morning for all
areas...

Friday night through Saturday night...as we go through the overnight
hours Friday night into Saturday..a northwesterly wind shift along
an Arctic front and associated surface low pressure system will
work its way east across the region. Chance and likely probability of precipitation are
through Saturday morning across western areas where 500 hpa
vorticity advection will elevate the chances of snow showers/snow
squalls near the front closer to the Great Lakes. As we go through
the day on Saturday...slight chance and chance probability of precipitation...especially
across western areas will continue with scattered lake effect
snow showers with a dominant northwesterly flow.

The main weather impact with this frontal system is in its
wake...very cold and likely dangerous windchill temperatures will
follow as we go throughout the day on Saturday into Saturday night.
Latest 12/00z model and numerical data shows a predominant
northwesterly flow advecting very cold air into the region. Some of
the latest data shows a strong upper level low pressure system
moving southeast into northern New York and New England by Saturday
night. Temperature data for h925 and h850 by 06z Sunday across the
region will range from -24c to -29c and -30c to -35c respectively.
With very cold temperatures and winds between 10 to 15 kts with
gusts higher than 20 kts at times during the afternoon hours on
Saturday...wind chill values will be very low well below zero across
the entire region. High temperatures on Saturday will be reached in the
early morning before falling steadily throughout the day. Low
temperatures on Friday and high temperatures on Saturday will remain
well below normal. As we go into Saturday night...low temperatures
will be the coldest values we have seen so far this season. Low temperature
values will range between -5 and -10 across the Lower Middle Hudson
Valley and southern Litchfield County to
-10 to -20 across the rest of the region...with the exception of the
Adirondacks where low temperatures will range from -25 to -35.

Sunday into Sunday night...the large cold upper level low pressure
system will move east into the Gulf of Maine by Sunday morning.
Another ridge of high pressure from the Ohio Valley will move
northeast into the region. Temperatures will modify slightly with
a wind shift to more of a due westerly direction. With high
pressure moving into the region...tranquil weather conditions are
expected under mostly clear skies. Temperatures on Sunday will
still remain well below average for middle February.

&&

Long term /Monday through Thursday/...
a significant storm is expected to impact the region during the
extended period...however...the exact types of precipitation and
amounts are still far from certain.

At the start of the period...cold high pressure will be departing
off the New England coast. After a very cold start on Monday
morning...the southerly flow around the departing area of high
pressure will allow temperatures to rebound into the 20s. Although skies
will start off mostly to partly clear...they will become mostly
cloudy by late in the day.

By Monday evening...an area of low pressure will be heading
northward from the deep south towards the southeast/middle Atlantic
coast. This system will have a surge of Gulf of Mexico and Atlantic
moisture running up the eastern Seaboard. At the same time...another
shortwave system will be diving across the Great Lakes...and will be
helping to influence the eventual track of this deepening southern
stream system.

Models suggest precipitation in the form of snow will break out
our region from south to north on Monday night thanks to the
strong warm air advection in place. A few inches of snow will
likely accumulate across much of the region on Monday night.
However...based on a consensus of the latest deterministic and
ensemble guidance...the strong warm air advection will allow temperatures
to rise above freezing aloft from south to north overnight. Precipitation
will start to mix with sleet/freezing rain across southern areas
by around 06z...and start mixing in the capital region towards
daybreak.

Ultimately...the duration/length of the changeover will depend on
the exact track of the storm....which is still yet to be determined.
A period of icing due to freezing rain could be possible in some areas if
cold air is able to hang in. The models currently suggest a track
very close to the aly County Warning Area...and a slight deviation to the west to
east could make a big difference on p-type...quantitative precipitation forecast amounts...and
temperatures. Based on the latest guidance...precipitation will start to change
from mixed to plain rain from south to north during Tuesday
morning...with much of the area seeing a plain rain by Tuesday
afternoon. The models are showing a large amount of quantitative precipitation forecast on
Tuesday...and the precipitation could be locally moderate to heavy at
times. East of the storm track...temperatures could rise well into the
40s...while west of the storm track will remain in the low to middle
30s. With the storm expected to be under 990 hpa and feature a
strong low level jet...there will be the possibility of some gusty winds...especially
for the higher terrain and across western New England. We will
continue to mention all these hazards in our severe weather potential statement statement.

As the storm lifts into northern New England and southern
Canada...it will continue to rapidly strength. With cold air rushing
behind the storm...any lingering precipitation will change back to snow
before ending on Tuesday night into Wednesday. There is the
possibility of some additional light snow accums with the backside
precipitation...but again...this will depend on the exact track of the
storm.

Mainly dry weather will seasonable temperatures will occur behind this
system for Wednesday night through Thursday. Some additional light snow
showers are possible late in the week with some passing northern
stream clipper systems as well.



&&

Aviation /09z Friday through Tuesday/...
flying conditions are currently VFR at all terminals. Aside from a
few passing leftover clouds from lake effect activity to the west of
the region...skies are mainly clear and will continue to be so
through the remainder of the overnight hours. West winds continue to
be around 5-10 kts for most sites...with a few higher gusts at times
near kpou/kpsf. However...approaching high pressure will allow winds
to diminish over the next few hours...with winds expected to be 5
kts or less by late tonight.

During the day on Friday...winds will be S-SW at around 5 kts. Skies
will be fairly clear to start the day...but will slowly increase by
the late afternoon hours or into the evening...with scattered-broken ceilings at 4-8
kft...with continued VFR conditions.

An approaching Arctic frontal boundary may allow for a rogue snow
shower or snow squall by later Friday evening into Friday
night...which could temporarily lower flying conditions from the
VFR conditions. Otherwise...it should continue to be VFR into Friday
night with broken-overcast ceilings around 4 kft...and SW winds around 5 kts.

Outlook...

Saturday: moderate operational impact. Windy. Scattered shsn.
Saturday night: low operational impact. Breezy. No sig weather.
Sunday: no operational impact. No sig weather.
Sunday night: no operational impact. No sig weather.
Washington's birthday: low operational impact. Slight chance of snow.
Monday night: moderate operational impact. Chance of snow.
Tuesday: high operational impact. Likely rain...sn...sleet.

&&

Hydrology...
with bitter cold air in place...ice coverage on rivers and lakes
will continue to increase and strengthen over the next few days. A
few light snow showers are possible...mainly this evening...but this
will amount to little of hydrologic significance.

However...there is the potential for a heavy precipitation event to
impact the region Monday night through Wednesday. There remains
considerable uncertainty regarding the types of precipitation that
may occur...which will ultimately depend on the exact track of this
potential storm system. At this time...model guidance is suggesting
one to three inches of liquid equivalent could occur...and much of
this could be in the form of rain. If this rain were to
materialize...it could have a high impact on rivers and
streams...especially considering the ground will be fully frozen by that
time...allowing much of the precipitation to be runoff. Details will
become more certain over the next few 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.



&&

Aly watches/warnings/advisories...
CT...wind chill warning from 1 PM Saturday to 1 PM EST Sunday for
ctz001-013.
New York...wind chill warning from 3 am Saturday to 1 PM EST Sunday for
nyz032-033-038-042-047-051-058-063-082.
Wind chill warning from 1 PM Saturday to 1 PM EST Sunday for
nyz039>041-043-048>050-052>054-059>061-064>066-083-084.
Massachusetts...wind chill warning from 1 PM Saturday to 1 PM EST Sunday for
maz001-025.
Vermont...wind chill warning from 3 am Saturday to 1 PM EST Sunday for
vtz013>015.

&&

$$
Synopsis...lfm
near term...lfm
short term...lfm
long term...frugis
aviation...frugis
hydrology...frugis

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