Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Albany New York
652 PM EDT Thursday Aug 21 2014

Synopsis...
a slow moving upper level low over the eastern Great Lakes region
will continue to bring showers and thunderstorms...some with locally
heavy rain...as it drifts eastward through tonight. The upper level
low will track off the coast tomorrow with a few lingering showers
and cool temperatures over the area. Improving conditions are
expected over the weekend as high pressure builds at all levels of
the atmosphere from Quebec into the northeast. It will bring increasing
amounts of sunshine and warmer temperatures into next week.

&&

Near term /until 6 am Friday morning/...
as of 652 PM EDT...an upper level low is currently situated over the
eastern portion of Lake Ontario. This upper level energy has
provided the lift for the showers and thunderstorms that have been
ongoing from the afternoon and into the evening hours so far.

With plenty of cloud cover in place...surface based instability is
limited...which is helping keep the threat for severe weather low.
The latest laps analysis shows only up to 1000 j/kg of surface based cape
currently present...with the highest values in the western and
southern parts of the County Warning Area. There is more surface based cape across
central New York and into NE PA...and these are the locations where a
handful of severe reports have occurred today. With the loss of
daytime heating...we see no reason why cape should continue to
wane...and keep the threat for severe storms from our area.
Thunder will continue to occur...as elevated instability will be
present.

Also...with precipitable waters above normal /around 1.63 inches from this
mornings kaly sounding/...dew points into the 60s...and high fzl
levels /fzl levels around 12000 ft/....the threat for heavy
rainfall will continue to be possible with any shower or
thunderstorm...as warm rain processes will dominate. Several
clusters of showers/thunderstorms have produced one to two inches
of rain in a short period of time...and a few flood advisories
have been issued to address these showers/thunderstorms. With
showers/thunderstorms still ongoing...especially across the
Adirondacks and Mohawk Valley...the threat for additional minor
flood concerns will continue...as this activity moves eastward.
Luckily...there is enough flow to keep the showers/thunderstorms
moving along...and prevent too much from falling over any one
particular location. Still...we will continue to monitor for the
potential for localized flooding over the next few hours. See our
Hydro discussion for more details.

Probability of precipitation taper down to chance for late tonight /by about midnight or so/ as
the core of the upper level low moves overhead...and the best
forcing starts to shift east of the area. However...it still looks
to remain cloudy through the overnight hours...with min temperatures
mainly in the upper 50s to middle 60s.

&&

Short term /6 am Friday morning through Saturday night/...
tomorrow...the upper level low will start to shift offshore.
However...cyclonic flow around this system will continue to allow
for the threat for some scattered showers...especially during daytime
heating. Any rainfall will be much lighter on Friday...as the best
moisture will be starting to shift south and east towards
southern New England. It still looks to stay fairly cloudy with
the upper low nearby...so temperatures will be held down. Maximum temperatures will
only be in the upper 60s to middle 70s.

The upper level low will continue to move away from the region
between Friday night and Saturday. A lingering sprinkle or shower
cannot totally be ruled out over the high terrain...otherwise it
looks to be dry. Finally...some breaks in the clouds will start to
occur...especially by Sat morning from north to south...as drier air
starts to work in from southern Canada. Min temperatures Friday night will
be in the 50s...with highs on Saturday in the 70s.

Upper level ridging will start to build into the area for Saturday
night from the Great Lakes and Ohio Valley. With clearing skies
and light winds...good radiational cooling can be
expected...allowing for temperatures to fall easily. Overnight lows will
range from the upper 40s over the Adirondacks to the middle 50s in
the capital region and middle Hudson Valley.

&&

Long term /Sunday through Thursday/...
high pressure dominates the weather over the region Sunday through
Wednesday with gradual warming each day as the high pressure builds
offshore. Highs Sunday and Monday in the middle 70s to lower 80s. Highs
Tuesday and Wednesday in the lower to middle 80s...with upper 70s to
lower 80s in higher terrain.

A weak cold front just begins to approach Wednesday night and
Thursday but the low level thermal ridging should still be in place.
So...just some isolated showers and thunderstorms Wednesday night
and Thursday with highs Thursday in the 80s.

&&

Aviation /00z Friday through Tuesday/...
primary 500hpa short WV is moving into fca west/its associated weak surface trough...and
scattered -shra/thunderstorms are evolving into more widespread -shra...and embedded
thunderstorms as they are mvng into areas of elevated cape. Ceilings and or
visibilities will be MVFR during this evening...with areas IFR in thunderstorms
this evening...becoming IFR overnight with lowering ceilings and areas of
fog forming. Winds will be light northeast to southeast this
evening becoming near calm overnight.

Friday the surface trough will linger near western periphery of fca...as several
500hpa short waves drop southeast in wake of the departing 500hpa cutoff.
Scattered-broken -shra will dim through the day as drier air filters in
llvls from high pressure building south under 500hpa ridge over
qb. Winds will becoming light NE. Ceilings/visibility will be MVFR much of the
day...impvg to VFR twrds evening.

Outlook...

Friday night: low operational impact. No sig weather.
Saturday: no operational impact. 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: no operational impact. No sig weather.
Tuesday: no operational impact. No sig weather.

&&

Fire weather...
showers and thunderstorms late this afternoon into tonight will
keep fire weather concerns at a minimum. Relative humidity values will be near
100 percent in most locations tonight. With clouds and scattered showers
around tomorrow...relative humidity values will remain above 70 percent through
the entire day...with light and variable winds.

&&

Hydrology...
showers and thunderstorms are currently moving across the region
thanks to a slow moving upper level low. These heaviest of these showers
and thunderstorms are producing heavy rainfall of up to two inches
per hour.

Some areas...generally from around Amsterdam northeast across the
Sacandaga Lake and into western Saratoga County...saw two to four
inches of rain last night. Some parts of the Adirondacks and
Mohawk Valley saw an additional one to two inches of rain with the
latest activity late this afternoon into this evening. Elsewhere...ground
conditions have been rather dry...due to a lack of recent
rainfall. As a result...most areas will be able to handle some
rainfall. However...if heavy rain occurs over those areas that saw
rainfall last night or if rainfall repeatedly moves over the same
location through into evening...then some minor flooding of
urban...poor drainage and low lying areas may occur. An isolated
flash flood cannot totally be ruled out...although any possible
flood issues would likely be more of the poor drainage/urban type
concerns.

The threat for heavy rainfall will end tonight...as the best
forcing starts to shift away from the area. Even though there may
some lingering rain showers into tomorrow...no additional heavy
rainfall is expected.

While there may be some rises on main stream rivers due to the
rainfall...no flooding of larger rivers is expected. With dry
weather returning for Sunday into next week...river levels will
recede and/or hold steady into next week.

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...frugis/Snyder
near term...frugis
short term...frugis
long term...NAS
aviation...irl/Snyder
fire weather...frugis
hydrology...frugis

National Weather Service Glossary of Abbreviations