Scientific Forecaster Discussion
fxus61 kaly 161117
Area forecast discussion
National Weather Service Albany New York
617 am EST Mon Jan 16 2017
high pressure will allow for seasonable temperatures
with plenty of sunshine today. A storm system approaching from the
Great Lakes will bring a wintry mix of snow, sleet and freezing rain
to the region for Tuesday into Wednesday. Afterward, temperatures
will be above normal for the remainder of the week with mainly dry
Near term /until 6 PM this evening/...
as of 617 am EST...surface high pressure is located over central
New England, which is allowing for clear skies over the majority
of our forecast area. The exception is a patch of lower clouds
over the western Adirondacks, which are in place due to a moist
flow off Lake Ontario upsloping the higher terrain. These clouds
should dissipate through the morning hours, allowing for a mostly
sunny sky across the entire region today.
As the high pressure area slowly slides eastward off the New
England coast, a light southerly return flow will develop this
afternoon. After a cold start, daytime temps look to reach the
30s across the area, with the warmest temps across the Mid-Hudson
valley and northwest CT.
Short term /6 PM this evening through Wednesday/...
..wintry mix expected Tuesday into Wednesday...
Low pressure will be lifting across the Midwest and plains towards
the southern Great Lakes tonight. Although skies will start off
fairly clear across our area this evening (allowing temps this
evening to drop off rather quickly), sky cover will gradually
increase and thicken as this storm system approaches. Skies look
to become mostly cloudy after midnight, and temps will stop
dropping and hold steady in the mid to upper 20s for the remainder
of the night. Any precip looks to hold off until after daybreak
As the low pressure area moves across the southern Great Lakes, it
will push a warm front towards the area. The low and mid level
flow out of the S-southeast will allow for warm air advection/isentropic
lift and some light precip looks to spread from southwest to
northeast across the area on Tuesday morning, becoming more
steadier and widespread by the afternoon hours. Model soundings
suggest a warm layer will be in place around 800 hpa. This warm
nose will allow for a variety of p-types across the area, as
boundary layer temps and the exact temp within the warm-nose will
determine what occurs across the area, which will vary greatly
from southwest to northeast and with elevation as well. Northern
and northeastern areas (such as the Adirondacks and southern
vermont) will likely stay mainly snow/sleet during this event,
while areas further south will see generally sleet changing to
rain. There's the potential for several inches of snow/sleet
across the Adirondacks, Lake George region into southern Vermont,
with the best potential across Windham County, VT, where locally
2-6 inches of snow will be possible.
Further south across the Berkshires/northwest CT, temps aloft will be
warmer, but some colder air trapped at the surface may allow for
a prolonged period of freezing rain for late Tuesday into Tuesday
night, as the departing high pressure area allows for some colder
air to remain locked in sheltered valley areas. In collaboration
with weather forecast office box, have gone with a Winter Weather Advisory for Tuesday
afternoon into Tuesday night to account for the potential for this
freezing rain across the Berkshires/northwest CT. Icing may locally
exceed 0.25", which will make for slippery travel and possibly a
few power outages.
Elsewhere, additional winter weather advisories will likely be
needed for other northern/high terrain areas for the wintry mix
threat, but the best chance for seeing fzra will be across the
higher terrain and eastern areas. Model soundings suggest that
surface temps could remain very close to freezing for areas
around 500-1000 ft in elevation, so a prolonged period of freezing
rain could also occur across the helderbergs and some parts of the
eastern Catskills and Taconics.
Across the capital region, the threat for a wintry mix looks only
to be a few hours initially on Tuesday afternoon, but the Tuesday
evening commute could be locally slippery in spots. Also, there's
also the chance that precipitation could start to go back to sleet
or even some snow by late Tuesday night, as the approaching upper
level shortwave trough starts to cool temps aloft, just before
precip starts to taper off. Temps on Tuesday into Tuesday night
will remain in the 30s, with northern/sheltered valley areas
staying right at or just below the freezing mark.
Behind the storm's occluded front on Wednesday morning, precipitation
will taper off to light rain or drizzle. Spots that remain below
freezing could still see some freezing rain, but as precip
lightens up, temps should be able to rise everywhere on Wednesday
morning above freezing by midday. There could even be a little
lingering rain into Wednesday afternoon thanks to the trough
overhead and cyclonic flow. As temps continue to cool aloft, this
could change to some light snow for the high terrain, but any
additional accumulation looks minor at this time. Temps should
rise through the 30s on Wednesday.
Long term /Wednesday night through Sunday/...
an gefs/wpc ensemble mean approach was utilized for this forecast
package as the 00z European model (ecmwf) remains an outlier for the end of this week
and into the start of the weekend with an aggressive wave impacting
A split flow across North America through the long term as energetic
Pacific systems come ashore and dig southward across the central and
Southern Plains states. The downstream affects will be a ridge
extending along the i95 corridor which should deflect most of the
activity upstream of our local region through most of the long term
portion of the forecast.
A weak trough axis is expected to cross the region Wednesday night
with the chance for some light scattered snow showers. Then the
ridge axis begins to evolve with building surface pressures across
the northeast corridor of the Continental U.S. Through most of the upcoming
weekend. At this time, a slight chance for some rain/snow showers
will be south of Albany toward the i84 corridor Friday night as a
weakening upper wave tracks east and off the middle Atlantic coast.
The next chance for more widespread precipitation appears to be
Otherwise, temperatures will begin near average then moderate to
above normal as thermal column moderates through the period.
Aviation /12z Monday through Friday/...
VFR conditions through this forecast cycle ending 12z/Tue.
Mainly clear skies with light and variable winds this early Monday
morning. Winds become a bit more southerly during the day at speeds
less than 10kts. Those winds become light and variable once again
Higher levels clouds will be on the increase today and thicken later
today into tonight. A solid broken to overcast conditions will
overspread the entire region overnight from southwest to northeast
with ceilings at 5000 feet or higher.
Tuesday: high operational impact. Definite rain...sleet.
Tuesday night: high operational impact. Definite rain.
Wednesday: moderate operational impact. Chance of
Wednesday night: low operational impact. Slight chance of
Thursday: low operational impact. Slight chance of
Thursday night: no operational impact. No sig weather.
Friday: no operational impact. No sig weather.
dry weather is expected today into tonight with high pressure in
control. A storm system will bring a wintry mix to the region on
Tuesday into Wednesday. Total liquid equivalent amounts will be
one half inch to one inch. Although some of this precipitation
will be frozen, some minor rises on rivers and streams can be
expected. However, no flooding is expected.
Behind this storm system, temperatures will average above normal
for the remainder of the week. Some snow melt over the Adirondacks
and southern Vermont may contribute to some additional runoff,
but any rises on rivers and streams will only be minor. Little (if
any) precipitation is expected for Thursday into the weekend.
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
CT...Winter Weather Advisory from 3 PM Tuesday to 7 am EST
Wednesday for ctz001-013.
Massachusetts...Winter Weather Advisory from 3 PM Tuesday to 7 am EST
Wednesday for maz001-025.