Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
750 PM EST Monday Nov 30 2015
a warm front will approach our area late tonight...spreading
clouds and eventually rain into the region. There is a chance that
the rain could start out as a little freezing rain...mainly north
and west of Albany Tuesday morning. A storm developing to our
south will prolong periods of rain into Wednesday...possibly
ending as a little snow Wednesday over the mountains.
Near term /until 6 am Tuesday morning/...
as of 730 PM EST...the stratus cloud deck had returned to the
southeast Catskills...the middle Hudson Valley...Litchfield County
and southern Berkshire County. At the same...higher clouds were
begining to spread into the region from the southwest. Have
adjusted the sky cover grids accordingly and forecast clouds to
increase from south to north during the night. Have also made
adjustments to the hourly temperature grids to account for current
we expect most areas toreach their low temperatures at or shortly
after midnight as the clouds continue to increase. Also...a
southerly gradient might re-introduce a modest south to southeast
breeze in some areas (mainly higher terrain areas).
It looks as if isentropic lift will be induced as a low level jet
increases toward daybreak...and especially Tuesday morning.
The critical and most difficult part of this forecast is when
will precipitation begin?
The NAM and some other sref members have been a little quicker moving
precipitation before dawn (overnight). Temperatures in this scenario
would likely be cold enough for some freezing rain in most areas.
However...this idea is not supported by the GFS and most of the geffs.
One or two members do have a little freezing for Albany (0.02 inches) but
the vast majority of the members do not.
The European model (ecmwf) did not have precipitation reaching our region until most
areas will safely above freezing.
For now...overnight we have only slight chances of precipitation
well to our south...slight chances of freezing rain in some cases
but again the emphasis is on slight.
Temperatures toward daybreak could rise a few degrees and by
dawn be right around freezing in the capital region...a few
degrees higher south but middle to upper 20s further north
in areas that look to remain dry.
Short term /6 am Tuesday morning through Wednesday night/...
the most questionable time for any freezing rain would
Tuesday morning. Precipitation looks to quickly break out
from southwest to northeast across the region as low level
jet increases...inducing isentropic lift. Precipitation looks
to locally reach Albany probably at the very tail end of the
morning commute. While we do not expect freezing rain here...
there could be few ice pellets initially mixed in with the rain.
A cold rain (or possibly freezing rain) will break out
across the region. The best chance of freezing rain
(and it is only a chance not likely) would be the
northwest and north and well northeast of the capital
region. Worse case scenario would see a few hours of freezing
rain in these spots...producing up to a tenth of an inch of
ice accretion but potentially very slick roads.
Per collaboration with the surrounding offices...we decided
not to issue any advisories at this time as confidence
for any freezing rain advisories was not that high at this time.
We will continue to highlight the possibility of freezing rain
in our hazardous weather outlook (hwo).
We strongly recommend you to check with our
forecast later this evening to see if we have any indications
precipitation would move in faster than we thought.
One thing we know...Tuesday will be gray raw day with rain...reaching
everywhere by afternoon. While not heavy...periods of rain will be cold
as high temperatures look to crest only in the middle to upper 30s
north and west of Albany...40-45 Albany south.
A warm front to south will never reach our area.
Energy from a broad low pressure extending from Minnesota will
allow a secondary new low pressure area to develop along
the eastern Seaboard by late Tuesday.
This secondary low pressure will ride up
along the coast...or possibly a little inland.
At this point it will be above freezing everywhere
in the column so only rain is expected. In fact...
temperatures should change very little Tuesday night
compared to Tuesday...averaging in the middle to upper
Periods of rain should continue through Tuesday night.
While models were in good agreement on this first low pressure...they differ
a just slight as we head into Wednesday.
The main front will trail behind the secondary low pressure...stalling
as another low pressure looks to form along it Wednesday. The GFS
and Canadian models are slightly faster with this third area of low pressure...
moving it off to our east (along with the front) Wednesday evening....while
the European model (ecmwf) moves it bit slower...not clearing our reaching until Thursday
morning. Either way...an the upper level portion of the storm overnight
the threat of showers will continue even though the steadier rain will
depart. At this time...the column will cool enough so that these showers
could turn to snow...especially across the higher terrain where a small
accumulation is possible by Wednesday morning.
Look for high temperatures in the 40s on Thursday (perhaps around 50
in the middle Hudson valley)...cooling to the lower to middle 30s
Thursday night with some upper 20s across the Adirondacks.
Long term /Thursday through Monday/...
the long term period will be characterized by mainly dry weather
with high pressure in control...except for some scattered rain/snow
showers primarily north of the capital region Thursday and Friday.
At the start of the long term period...long range guidance continues
to be in good agreement during the long term period...starting with
an upper-level low situated across much of the northeast. This upper-
level low will be gradually opening up and weakening with time...but
still have pieces of shortwave energy rotating through the base of
the trough as the trough axis swings through the region during the
day Thursday. This will promote scattered rain/snow showers mainly
north of the capital region and across higher terrain locations. Any
snowfall accumulations will be limited to the higher terrain of the
southern Adirondacks and southern greens...where generally a few
tenths to a little over a half an inch of snow will be possible.
Cyclonic northwest flow and one last piece of shortwave energy
rotating through the upper-level flow will continue Thursday night
through Friday night...with widely scattered upslope rain/snow
showers possible across the windward facing slopes of the southern
Adirondacks. Any snow accumulation will be light on the order of a
few tenths of an inch.
Sprawling high pressure will build across the region for the weekend
and start of next week resulting in a period of dry weather and
partly cloudy skies.
Temperatures will be near average during the long term period...with
highs ranging from the upper 30s to upper 40s...except for some low
to middle 30s across the highest terrain of the southern
Adirondacks...and lows ranging from the middle 20s to lower 30s.
Aviation /01z Tuesday through Saturday/...
mainly VFR (p6sm skc) conditions this evening hours will slowly
give way to a stratus deck with MVFR/VFR ceilings between 2500 and
4000 feet early tonight.
Middle/high clouds will also be increasing later tonight and
eventually bring rain to the kalb/kgfl/kpou/kpsf taf sites. The
rain will spread from south to north...starting at kpou around
sunrise...and eventaull reaching kgfl around midday. There is
some concern that rain could initially start as freezing at any of
the taf sites...but right now this threat remained very low to
even mention a prob30 group. For now...we just went vsch but keep
in mind there could be a brief freezing rain sprinkle early
tomorrow morning. Any light freezing rain should change to rain
quickly and again the threat was very low.
Once the steady rain begins to move...ceilings and visibilities will
deteriorate...becoming IFR at kpou after around 15z...16z at
kpsf...18z at kalb...and 20z kgfl.
Surface winds will be light and variable or calm tonight and
through most of the day on Tuesday...but will become southeast at
8 kts or less at kalb/kpsf.
Tuesday night: high operational impact. Periods rain.
Wednesday: moderate operational impact. Periods rain.
Wednesday night: moderate operational impact. Likely rain.
Thursday: low operational impact. Slight chance of rain showers.
Thursday night: no operational impact. No sig weather.
Friday: no operational impact. No sig weather.
Friday night: no operational impact. No sig weather.
Saturday: no operational impact. No sig weather.
this will be the last issuance of our fire weather product...
nfdrs (already sent) and fire weather aviation afd.
Remember...our fire weather grids will continue to be populated
twice a day through the year.
Dry and seasonably cold tonight with a nearly full recovery.
Rain will overspread the region on Tuesday...possibly starting
as a brief period of freezing rain in the colder sheltered
valleys away from the capital region.
Periods of rain are expected Tuesday night into Wednesday
before precipitation tapers off to rain or snow
showers Wednesday night.
Thursday will be breezy with widely scattered rain or
mountain snow showers...especially north of Albany.
hydrologic problems are unlikely over the next five days.
Dry tonight but rain develops on Tuesday possibly starting
out as a little freezing rain in the colder sheltered valleys.
Periods of rain (mostly light) expected Tuesday night into early
Wednesday night...tapering to showers of rain or snow
late Wednesday night.
Rainfall amounts look to be around an inch region wide...possible
a little more in the favorable upslope areas of the higher
This rain will probably produce some within bank rises on rivers and
streams...but at this time...no rivers or streams are forecast to
reach action stage.
Drier weather returns later 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