Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Albany New York
429 PM EDT Thursday Apr 17 2014

Synopsis...
high pressure will dominate our weather through Friday
with temperatures moderating toward normal levels. However...a weak
disturbance in the upper levels of the atmosphere will move across
the region Friday night into early Saturday bringing some showers to
the area mainly to the north and west of the capital district. High
pressure will build in from Canada to close out the weekend.

&&

Near term /until 6 am Friday morning/...
cirrus clouds will continue to further diminish across the Mohawk
Valley...Adirondacks and Lake George Saratoga region as we go into
the late afternoon hours.

As we go into tonight...tranquil weather conditions under mostly
clear skies will dominate the region as high pressure over northern
Maine will continue to influence our near term forecast.
Temperatures will drop to below average values ranging between the
lower 20s in the Adirondacks to middle and upper 20s in valley
locations. Winds will be light and easterly. Enhanced flow between
10 to 15 miles per hour is expected in some areas across the Berkshires into
the southern Green Mountains.

&&

Short term /6 am Friday morning through Saturday night/...
a elongated domain of high pressure expanding from the Ohio Valley
northeast into the Canadian Maritimes will dominate the first half
of Friday with tranquil weather conditions. Latest 12z model and
numerical guidance shows a secondary high pressure system off the
coast of New Jersey that will enhance a southerly to southwesterly
wind flow developing Friday afternoon. This wind flow in conjunction
with an approaching upper level low will work to funnel into the
region a large Continental dry airmass from the Ohio Valley.

This shows a decreasing trends in 12z model probabilistic guidance
and numerical calculations of a low probability of precipitation and quantitative precipitation forecast setting up for
Friday night into Saturday. Latest 12z models run outputs show an
agreement of the upper level system moving faster across northern
New York along the Canadian border. With a weakening cold front
trailing the moisture starved system with dry air in the lower
levels. As we go into 00z Saturday as the system approaches...t850
and t925 winds will drive temperatures at the respectable level
between 1c to 3c and 4c to 6c. This will support a mainly liquid
precipitation event with the exception of a possible rain/snow
mixture in the highest elevation of the Adirondacks with no snow
accumulation expected at this time. Highest probability of precipitation and quantitative precipitation forecast will be
confined to the Adirondacks where only chance probability of precipitation exist as the best
upper level forcing downstream of the absolute vorticity advection
on the downstream side of the upper level trough axis near the
US/Canada border just north of our County Warning Area. Quantitative precipitation forecast amounts
at this time will be around a tenth of an inch. High temperatures on
Friday will range from the lower 50s to upper 50s. Low temperatures
with an enhances southwesterly flow will range only from near
freezing in the Adirondacks to middle and upper 30s for the rest of the
region.

As we go into Saturday...winds will switch to a more westerly
direction behind the departing upper level low as we go into 12z
Saturday. With the departing upper level low and an upper level
ridge over the Great Lakes...the height gradients will deepen
between the two upper level systems which will lead to gusty
westerly flow which at times may gust between 20 and 25 miles per hour.
Tranquil weather conditions will return Saturday as the region sits
downstream of the large ridge over the Great Lakes with large
surface divergence present over the region. Temperatures on
Saturday will range from the lower 50s in the Adirondacks to lower
60s int he middle Hudson Valley. Low temperatures on Saturday under
clearing skies will range from the middle 20s to lower 30s across the
region.

&&

Long term /Sunday through Thursday/...
overall model guidance is in good agreement with the longwave
pattern which become more amplified as we head into next week. Flow
will be zonal across the Great Lakes region and across the northeast
to start out the period with a ridge building over The Rockies early
next week. The ridge will shift eastward as an upper low moves into
the Pacific northwest. As this occur shortwave energy will dive
southeastward out of central Canada digging a trough over over the
Great Lakes region by middle week.

Dry weather will persist into early next week with chances for
precipitation increasing as we head into Tuesday as a low pressure
system and its associated cold front move into the region. There are
some model differences with the amplitude of the system which ties
into the shortwave energy dropping out of Canada. At this time the
bulk of the precipitation would be Tuesday.

Temperatures are expected to be around normal Sunday with above
normal ahead of the cold front Monday and Tuesday...cooling back
down to normal for middle week.

&&

Aviation /21z Thursday through Tuesday/...
VFR conditions are expected through the taf period...18z/Friday as
high pressure dominates. High level cirrus clouds will continue to
stream over the region into this evening. Mainly clear skies are
expected overnight with more cirrus streaming in on Friday
especially in the afternoon.

Winds vary from northeast to southeast at the taf sites and will
remain light. Winds will diminish this evening with calm winds
expected to develop overnight. A light southeast to south flow will
develop Friday morning.

Outlook...
Friday night: low operational impact. Slight chance of rain showers.
Saturday: low operational impact.Breezy no sig weather.
Saturday night:no operational impact. No sig weather.
Sunday: no operational impact. No sig weather.
Sunday night: no operational impact. No sig weather.
Monday: no operational impact. No sig weather.
Monday night: moderate operational impact. Slight chance of rain showers.
Tuesday: moderate operational impact. Chance of rain showers.



&&

Fire weather...
recent rainfall and snowfall we have in the past one to two days has
made the ground have a good moisture content. Relative humidity values will recover
to values between 70 and 80 percent with light winds and clear skies.

As we go into Friday...the wind will turn south to southeasterly 10
to 15 miles per hour. Relative humidity values look low...but not quite as low as this
afternoon.

Friday night into early Saturday there could be some showers of rain
or snow around...mainly north of Albany. Amounts look
light...generally well under a quarter of an inch.

By Saturday afternoon...the wind will turn northwesterly behind the
disturbance as it become breezy...especially in the Mohawk
Valley/higher terrain and capital region where wind gusts could
exceed 25 miles per hour at times. Sunshine will increase.

&&

Hydrology...
riverbank on the Schroon river is at major flood and has crested.
Based on current forecast it is only expected to drop to below
moderate flood stage Saturday morning with many more days until it
falls below flood stage.

Overall looking at dry weather into early next week. Some light
precipitation is possible Friday night into Saturday mainly north
and west of the capital district. Main stems rivers will continue to
recede. Our next widespread chances for precipitation is not
expected until Tuesday.

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...iaa/lfm
near term...lfm
short term...lfm
long term...iaa
aviation...iaa
fire weather...hwjiv/lfm
hydrology...iaa/lfm