Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
636 am EDT Sat Sep 20 2014
surface high pressure will slide further offshore today. The
return southerly flow of air will result in a milder weekend as
temperatures climb above normal. A cold front approaches on Sunday
with a good chance for showers...perhaps a thunderstorm too.
Cooler and brisk conditions in the wake of the frontal passage
return Sunday night into Monday. Most of next week looks dry and
near seasonable temperatures.
Near term /through tonight/...
as of 630 am EDT...stratus deck has nearly overtaken the region
per 11u-3.9u and metars this early Saturday morning. Temperatures
were already climbing and have adjusted hourly grids accordingly.
As for drizzle...no reports as of yet despite model quantitative precipitation forecast/S
attempting to suggest this idea /mainly into the terrain/. No
other changes at this time to the remainder of the near term
Previous disc...1030mb surface high was centered over Nova Scotia.
Pressure gradient has increased across the northeast
corridor...along with low level moisture. The latest 11u-3.U
satellite imagery this morning nicely depicts the ever-expanding
stratus deck extending along the Appalachian Mountains into
western New England. This will be the initial forecast challenge
as too the extent and longevity of this stratus deck. Latest model
relative humidity fields suggest this stratus deck will linger across most of the
region through this morning. However...through the day...overall
wind magnitudes increase which should assist with mixing potential
and some breaks in clouds for partial sunshine. Despite the
clouds...the thermal column is milder and per our forecast mixing
layer heights today...we should see valley temperature approach or
just exceed 70f with 60s elsewhere.
The southwest flow will persist into tonight with a partly cloudy
sky. Surface winds should remain elevated due to the persistent
gradient across the region. Overnight lows will be mild as
dewpoints climb through the 50s keep lows ranging from the upper
50s to lower 60s. There could be some showers/drizzle developing
across areas south of i90 as additional entrainment of Atlantic
moisture is expected.
Short term /Sunday through Monday/...
approaching cold front and stronger height falls with increasing
shear profiles all point toward an organized area of showers
moving through the region. As per the previous
forecast...instability parameters remain weak but elevated enough
to continue with the slight chance for thunderstorms. Per timing
of when peak heating and low level convergence occur...this
appears to line up across the Mohawk Valley and Adirondack region.
In fact...this lines up with the swody2 5% contour. So we will
remain with the scattered to likely probability of precipitation on Sunday. Still a mild
day in store as valley locations should climb well into the 70s
/maybe 80f for the middle Hudson Valley and southern Litchfield
County/ and 60s elsewhere.
Frontal passage timing differs from the NAM as it remains much slower than
the other available guidance...so we favored the consensus
approach of a bit faster timing. Nevertheless...there will still
be a strong upper level short wave moving through overnight Sunday
into Monday. Low level moisture remains quite high so can not rule
out another shower or two in the wake of the frontal passage. Temperatures
will begin to drop back within the cold advection as the zero
degree isotherm at h850 is proged to be over eastern New York on Monday.
West- northwest winds too will be increasing Sunday night into
Monday as combination of tight gradient and mixing layer heights
between h800-h900 yields gusts to around 20kts.
Long term /Monday night through Friday/...
an upper level trough will be situated over the northeast to
start the extended period. A shortwave will dive through the main
upper trough over southern Canada for Monday night into Tuesday.
Although the bulk of the upper level dynamics will remain north of
the region...it may be close enough for an isolated shower across
far northern areas between Monday night and Tuesday. Otherwise...it
will be dry with a partly cloudy sky for the remainder of the
area. Mins Monday night will be in the upper 30s to middle 40s...and
highs on Tuesday will be in the upper 50s to upper 60s.
A large sprawling area of high pressure will then take over and
control the weather through the remainder of the week. The high will
move from over the Great Lakes on Tuesday/Tuesday night towards upstate
New York/New England for Wednesday...and off the coast for thurs/Fri. This
high pressure allow will allow for dry conditions with mostly clear
skies. Temperatures will gradually warm up throughout the week...with
valley highs in the middle to upper 60s on Wednesday...to near 70 on
Thursday...and low to middle 70s for Friday. With the clear skies and
light winds...good radiational cooling will occur each night...and
lows will generally be in the 40s /some upper 30s over the high
terrain. Most areas that still have the growing season ongoing look
to avoid a frost/freeze through the upcoming week.
Aviation /12z Saturday through Wednesday/...
with a southerly flow in place...bkn-ovc low clouds have moved
into the region. For the valley terminals...flying conditions are
still VFR...with ceilings at 3500-5000 feet. Meanwhile...kpsf has seen
MVFR conditions with ceilings around 2-3 kft. Although we cannot
totally rule out some MVFR ceilings at kgfl...flying conditions look
to stay VFR for the valley terminals...and MVFR for kpsf. Based on
upstream conditions and model soundings...no IFR conditions are
expected through the morning hours.
By the middle morning hours...daytime mixing will help thin out the low
clouds...and kpsf should return to VFR conditions as well. Scattered-broken
clouds at 4-7 kft will then be in place through the remainder of the
day. Southerly winds will continue to be around 10 kts with some
higher gusts in the Hudson Valley.
With the continued southerly flow in place...a return to MVFR ceilings
is possible for all sites tonight...especially kpsf. Southerly winds will
continue around 5-10 kts. Confidence in IFR conditions occurring is
low at this time...so we will not mention any IFR with this taf
issuance. It should remain dry...as any showers look to hold off
until Sunday as well.
Sunday night: moderate operational impact. Chance of rain showers...tsra.
Monday: low operational impact.Breezy slight chance of rain showers.
Monday night through thursday: no operational impact. No sig weather.
low level moisture will be increasing through the weekend which
will keep relative humidity fields a bit elevated with values ranging between 50
and 70 percent. Those values increase to between 80 and near 100
percent tonight with the chance for some showers.
The shower potential increases on Sunday with a moist atmospheric
profile to keep relative humidity values at or above 60 percent.
Southerly winds of 10 to 15 miles per hour with some higher gusts
today...remain near 10 miles per hour tonight then return to between 10 and
15 miles per hour on Sunday with some higher gusts.
no widespread Hydro problems are expected through the weekend and
into next week.
A low pressure system will approach and cross the region this
weekend bringing some much needed rainfall to the area Sunday into
Sunday night. Rainfall amounts are anticipated to generally be a
quarter to a third of an inch with higher amounts of 1/2 to 1 inch
across the southern Adirondacks and lower amounts of less than a
quarter inch across the middle Hudson Valley and Litchfield County.
A return to dry weather is expected for most of 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.
For the latest updates...please visit our webpage at