Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
217 PM EDT Sat Sep 20 2014
high pressure will hold on for one more day. Southerly winds will
help warm temperatures close to normal levels this afternoon and
above normal on Sunday. A low pressure system and the associated
cold front will approach from the west on Sunday...bringing some
rain showers to the area...along with the threat of thunder. Cooler
and brisk conditions in the wake of the frontal passage will return
for Sunday night into Monday. Most of next week looks dry...with
Near term /through tonight/...
the ridge centered off the New England will provide the area with
another fair weather day...although there will be partly to mostly
cloudy skies. The region will be in the warm sector this afternoon
with highs expected to be around 10 degrees warmer than Friday...
in the middle 60s into the middle 70s.
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 /18z Saturday through Thursday/...
have deep southwesterly flow across the region as its squeezed
between the departing ridge and an approaching low pressure system.
It has been gradual but the clouds are lifting and breaking up. This
will continue through the afternoon hours into the early evening.
MVFR ceilings persist at kpsf...however they are expected to
improve to VFR. A brief period of scattered cloud should occur.
However...tonight lower clouds will return with MVFR and IFR
conditions expected to develop especially for the overnight hours.
Conditions are expected to gradually improve Sunday...however
MVFR should persist into the early afternoon.
A vigorous short wave is diving into the longwave trough over the
region and will result in the development of a low on the cold front
approaching from the west. In addition...a low has develop along the
southeast coast. The pattern remains progress and the front and its
associated low will pass through the region Sunday as the coastal
low will move northeastward passing south of Long Island and Cape
Some isolated to scattered showers are expected to move across the
southeast portion of the forecast area in association with the
coastal low late tonight and early Sunday morning. Have addressed
this threat with vcsh in kpou and kpsf tafs. As for showers
associated with the cold front...they should hold off until after
18z/Sunday so no mention in tafs at this time.
Southerly winds will continue through the taf period. They will be
gusty this afternoon and will weaken tonight.
sun night: moderate operational impact. Chance of rain showers...tsra.
Mon: low operational impact.Breezy slight chance of rain showers.
Monday night-Thu: 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.