Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Albany New York
909 PM EST Friday Nov 28 2014

Synopsis...
high pressure will briefly ridge into the region tonight with cold
temperatures and clearing skies. The surface high will drift off the
middle Atlantic coast tomorrow...as a warm front will approach from the
lower Great Lakes region and Pennsylvania Saturday night with a
light mix of precipitation. Milder weather will return for
Sunday...as temperatures moderate closer to normal to close out the
Holiday weekend.

&&

Near term /until 6 am Saturday morning/...
as of 900 PM EST...disorganized lake effect/enhanced snow showers
and flurries continue in the west/northwest flow across parts of eastern New York and
western New England. The scattered snow showers are the most numerous on the
kenx radar across the capital district...Mohawk Valley...northern Berkshires.
As indicated by the hrrr and hireswrf model comp reflectivity this
activity will diminish over the next several hours as the flow
moves back to the west and band loses its lake connection.

This also makes sense with the lowering inversion...and surface
anticyclone building in. The low-level flow will back and become
more westerly...so the best chance of an inch or so of snow will be
in the western dacks...prior to 06z/Sat...and then we have diminished
probability of precipitation thereafter. As the ridge builds in across the middle Atlantic
region...and the northeast...expect the skies to become clear or
partly cloudy. Some radiational cooling is expected with the
partial clearing with light to calm winds...and a fairly fresh
snow cover.

Low temperatures will be tricky...as the gfsmos values are about 10 to
15 degrees colder than the metmos values. We have gone with a
blend of the guidance values...and a shade closer to the European model (ecmwf) MOS
guidance. Lows will be in the teens from the capital district
south...and 5-10 degrees to the north.

&&

Short term /6 am Saturday morning through Sunday night/...
Saturday...the h500 flow becomes zonal...as the surface high begins to
shift off the middle Atlantic coast. A warm front will be approaching
from the Great Lakes region...and Ohio Valley. Most of the day
should be dry with an increase of middle and high clouds during the
afternoon. The return flow from the surface high will help increase the
warm advection over the forecast area...as h850 temperatures rise to -1c to
-4c by 00z/sun. Some scattered snow showers due to the increasing
isentropic lift may move into locations north and west of the
capital region before sunset. Highs will still be on the cold side
with highs in the u20s to m30s in the valley areas...and mainly
20s over the higher terrain.

Saturday night...tough part of the forecast where low and middle level
warming will continue with the warm front approaching from
PA...and the eastern Great Lakes region. Critical partial thicknesses
and BUFKIT model soundings for kalb/kgfl/kpou from the NAM and GFS
indicate a very light wintry mix of snow to sleet/freezing rain is
possible. The strongest qg forcing from the isentropic lift is over
the northern zones...especially north of the capital region. We have
placed a slight or low chance of -fzra and/or -ip in the forecast
especially after midnight. This could be a situation where a
Special Weather Statement could handle the very light mix...but we will
mention it in the severe weather potential statement with the slight and low chance probability of precipitation. Temperatures will
be rising...and model quantitative precipitation forecast from the NAM/GFS/ECMWF/Canadian guidance
is generally 5 hundredths or less. A non-diurnal temperature trend was
used in the forecast...as done by the previous shift...with lows in
the 20s to l30s prior to midnight.

Sunday to Sunday night...the warm front lifts north and east of
the region with any spotty mixed precipitation early on transitioning to
light rain showers or drizzle. Snow melt will likely occur...as
h850 temperatures pop up to +3c to +5c...and surface temperatures are expected to
be in the lower to middle 40s with some u40s across western New
England...and the middle Hudson Valley. A weak impulse or prefrontal
trough ahead of the main cold front may bring isolated-scattered showers
into the forecast area late Sunday afternoon into Sunday night. Clouds
should dominate in the warm sector on Sunday...and the better chance
of rain showers will shortly before or just after
midnight...especially north and west of the capital district. Lows
will be in the middle and u30s for most of the region Sunday night.

&&

Long term /Monday through Friday/...
at the start of the extended period...a frontal boundary will be
moving through the region early on Monday. Not that much moisture
associated with this front so probability of precipitation have only been forecast in the 30
to 50 percent chance range...with the highest probability of precipitation over the
Adirondacks. Much colder air behind this front...but Monday will
still be relatively mild with highs in the upper 30s and 40s.

The colder air will definitely be felt Monday night when temperatures drop
to lows in the teens to middle 20s...and there will be isolated snow
showers.

Fair but cold Tuesday and early Tuesday night as a large surface
high moves across the region. Mainly clear to partly cloudy skies
expected with highs Tuesday in the 20s to lower 30s. Later Tuesday
night clouds will increase as another frontal boundary approaches
from the northwest. There will also be a chance of snow late at
night. Lows will be in the upper teens and 20s.

This frontal boundary will be very slow to move south...so the
chance of precipitation will linger into at Wednesday night. The GFS even
suggest the front will stall over the region with a prolonged period
of precipitation. Have followed NCEP guidance for the period Thursday through
Friday with a generally dry forecast Thursday and Thursday night...
and then a chance of precipitation again on Friday.

Milder again on Wednesday with highs in the upper 30s and 40s. Lows
Wednesday night in the middle 20s to lower 30s. A little colder
Thursday and Friday with highs in the 30s and lower 40s. Lows
Thursday night 20 to 30.

&&

Aviation /02z Saturday through Wednesday/...
mainly VFR conditions expected at the taf sites through the end of
the taf period ending at 00z Sunday as a high pressure ridge
moves across the region during the period. Mainly just scattered clouds
overnight...with increasing middle level cloudiness Saturday morning
as a warm advection pattern takes hold.

Winds will be west 3 to 9 kts. This evening. Mainly light winds
overnight...generally less than 5 kts. Winds will shift to
southerly on Saturday at 4 to 8 kts.

Outlook...

Saturday night: moderate operational impact. Chance of shsn...fzra...sleet.
Sunday: low operational impact. Slight chance of rain showers.
Sunday night: moderate operational impact. Chance of rain showers.
Monday: moderate operational impact. Chance of rain showers.
Monday night: low operational impact. Slight chance of shsn.
Tuesday: no operational impact. No sig weather.
Tuesday night: moderate operational impact. Chance of shsn.
Wednesday: moderate operational impact. Chance of rain showers...shsn.

&&

Hydrology...
no significant hydrologic problems are expected the next 5 days
ending Wednesday.

Additional light precipitation amounts are expected with basin
averages at a tenth of an inch or less the next few days.

Snowfall accumulations will be a coating to a few inches with the
higher amounts downwind of Lake Ontario into portions of the western
Mohawk Valley and western Adirondacks.

A warm front will bring a light mix of precipitation Saturday
night into early Sunday morning.

Milder temperatures are expected Sunday with some snow melt. However...
temperatures are expected to cool off quickly during Monday with
the passage of a strong cold front. Additional quantitative precipitation forecast will be light
with a few hundredths to a tenth of an inch.

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...none.
Massachusetts...none.
Vermont...none.

&&

$$
Synopsis...wasula
near term...11/wasula
short term...wasula
long term...gjm
aviation...gjm/11
hydrology...bgm/wasula

National Weather Service Glossary of Abbreviations