Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
203 PM EDT Tuesday Sep 2 2014
high pressure offshore will supply the region with another day of a
southwest flow which will bring very warm temperatures once more. A
cold front will approach the region late today into the evening
bringing showers and thunderstorms...some of which could contain
heavy rainfall and gusty winds. Slightly cooler and noticeably drier
air will follow on Wednesday. The dry weather is expected to
continue the rest of the work week with warming temperatures once
Near term /through tonight/...
some isolated to scattered showers are exiting...but more isolated
showers tracking into the Schoharie valley and heading toward the
helderbergs. Partly to mostly sunny spreading east now and even
though temperatures have been slow to rise in some areas...
should rise to near forecasted levels by late this afternoon.
Better upper dynamics and low level forcing are in the eastern
Great Lakes and Ohio Valley where organized convection is expected
to form and track across the region this afternoon and tonight.
Instability and increasing low level jet energy could support
isolated marginal severe wind gusts and locally heavy rain.
Some minor adjustments to temperatures...rain chances and sky
cover through this afternoon...until new convection develops and
can refine forecast later based on newer data. Highs well into the
80s to around 90 with increasing coverage of showers and
thunderstorms through this afternoon and evening.
Rain should end tonight with partial clearing and lows in the middle
50s to lower 60s.
Short term /Wednesday through Thursday night/...
Wednesday will feature a good deal of sunshine...a northwest breeze
10-15 miles per hour and high temperatures 80-85 in the valleys (warmest near
poughkeepsie) middle to upper 70s over the higher terrain. Dewpoints
will drop into the 50s.
Wednesday night as high pressure moves overhead...and the sky is
expected to clear...temperatures will dip into the 50s region wide
with middle to upper 40s across the Adirondacks and portions of the
southern greens. It looks as if some patchy fog should form
Thursday...high pressure will begin to drift offshore...allowing a
southerly flow to begin to pump warmer and slightly more humid air
back into the region. Highs will reach around 80 over the higher
terrain...closer to 85 in the valleys. Dewpoints will be around
Thursday night will be mild with lows ranging from the upper 50s in
outlying areas...60s most other places...locally upper 60s in the
Long term /Friday through Monday/...
the large and warm high pressure system will hold over the region
for most of Friday with slowly increasing clouds expected and highs
in the 80s as 850 mb temperatures reach +16 to +18 degree celsius. Late in the
day there is a chance of showers or thunderstorms across the northwest part
of the forecast area as a cold front and upper level trough approach
from the west.
Friday night into Saturday...most active portion of the long term with
a cold front interacting with a moist and unstable air mass. Model
timing of the boundary is still variable...but the models are closer
than they were 24 hours ago. All the medium range models now agree
that any showers associated with this frontal boundary will be out
of the region before Sunday...with some models much sooner. Will
continue to keep chance probability of precipitation across the region Friday night and
Saturday...then lower probability of precipitation to only slight chance by late Saturday
night. Lows Friday night will be in the upper 50s and 60s. Highs
Saturday in the upper 60s across the Adirondacks...and the 70s to
lower 80s elsewhere. Lows Saturday night in the upper 40s and 50s as
the cooler air behind the front begins to seep in.
On Sunday a sprawling high pressure system will build into the
region and control our weather into early next week. This high
pressure area is of Canadian origin so it will be noticeably cooler
Sunday and Monday. Highs Sunday and Monday will be in the middle 60s to
middle 70s. Lows Sunday night in the middle 40s to middle 50s.
Aviation /18z Tuesday through Sunday/...
a cold front moves across the region this evening with scattered showers
and thunderstorms. The front should be south of eastern New York and western New
England by daybreak tomorrow with high pressure building in from
the Ohio Valley.
VFR conditions will persist this afternoon with scattered cumulus and
scattered-broken cirrus. An isolated shower or thunderstorm is possible prior
to sunset. An organized band of showers and scattered thunderstorms will
reach the Hudson Valley between 01z/Wednesday and 04z/Wed. This frontal band
of showers and thunderstorms will produce MVFR ceilings/visibilities with
isolated IFR conditions. Thunderstorms may be needed to be added to
the taf later. It has been placed in kpou at this time.
In the wake of the front some MVFR/IFR visibilities/ceilings may linger at
kpsf/kgfl/kalb until the stronger cold advection arrives towards 12z/Wed.
VFR conditions should arrive between 11z-13z/Wed.
The winds will be from the S/SW at 5-10 kts shifting to the west/SW
at 5-12 kts 00z-04z/Wednesday with the front. The winds will continue to be
from west/northwest at 6-12 kts after 12z/Wed.
Wednesday to friday: no operational impact. No sig weather.
Friday night to saturday: moderate operational impact. Chance of
high pressure will move east of our region today allowing a cold
front to move in late today into this evening. This front will bring
another round of showers and thunderstorms to the area...mainly late
this afternoon into the early evening hours.
It will be a rather hot day with partial sunshine before the showers
and storms arrive. Relative humidity values will only drop to the 55-65 percent
range this afternoon. A south to southwest wind will average 5-15
miles per hour.
Rainfall from the thunderstorms look reach around a quarter inch or
better in most areas from Albany northward...a quarter inch or less
south of Albany. However...any thunderstorm could produce heavy
rainfall producing localized amounts easily exceeding an inch in any
Relative humidity values tonight will be in the typical 80-100 percent range
although a bit of breeze might persist in many areas...as the wind
shifts from southwest to northwest.
Wednesday will feature lower humidity along with a good deal of
sunshine. A northwest breeze will average 10-15 miles per hour with some higher
gusts into the 20s...mainly over the higher terrain/Mohawk Valley
and greater capital region. Afternoon relative humidity values will drop into the
35-45 percent range.
A full recovery Wednesday night with the wind going calm...and relative humidity
values near 100 percent with plenty of dew expected.
The next chance for showers and thunderstorms will be late Friday
it will be mainly dry through midday. Then...shower and thunderstorm
coverage should increase from northwest to southeast through the
afternoon into the early evening. Average basin rainfall with these
storms is projected to be around half an inch across northern areas
of our hydrological service area (hsa)...north of Albany. Look for
around half an inch in and around the capital region...and lesser
amounts of a quarter inch or less further south.
Precipitable waters are expected to exceed two inches today. This will allow for
the potential for any thunderstorm to produce locally much heavy
rainfall...possibly exceeding an inch and this rain could fall in a
short time. Therefore there is the potential for significant ponding
of water on roadways and areas of poor drainage. While the threat
for any organized flash flooding is very low...a high localized
flash flood cannot be ruled out.
Drier weather returns by Wednesday...lasting through the remainder
of the workweek.
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.