Scientific Forecaster Discussion
fxus61 kaly 260152
Area forecast discussion
National Weather Service Albany New York
952 PM EDT Tue Jul 25 2017
as an upper level disturbance departs tonight, clouds
will start to break up, although lingering moisture will allow for
some patches of fog. Once any morning fog breaks up, dry and
comfortable weather is expected for Wednesday. An approaching
frontal system will bring some showers and thunderstorms for
Thursday, but clearing conditions are expected for the weekend.
Near term /until 6 am Wednesday morning/...
showers have dissipated and clearing continuing to spread west
from New England. Did some minor adjustments to cloud cover and
took the isolated showers out of the forecast for the rest of
the night. Cannot rule out a sprinkle or two, though, in some
places tonight as cloud cover mixes out as subsidence increases.
A few more details are in the previous afd which is below...
There could be some patchy fog and low clouds near rivers and
swamps in western New England once the clearing occurs late
tonight and radiational cooling drops temperatures below water
temperatures. So, just a few changes to timing of the end of the
isolated showers and some of the trends in the clearing from
west to east.
In the wake of the departing storm, plenty of lingering low
level moisture remains, which is allowing for a lot of stratus
and stratocu clouds over the area. Although some drier air will
start to work its way into the area tonight, clouds will
probably remain in place for most areas. For where clouds do
break up, some areas of fog may develop, especially by late
tonight. Lows will mainly be in the 50s, although some upper
40s are possible over the central and eastern Adirondacks.
Short term /6 am Wednesday morning through Friday/...
surface high pressure will allow for dry and comfortable weather
on Wednesday. Although the day may start with some fog/low
clouds, it should break up shortly after sunrise. With strong
subsidence overhead, skies should become mostly sunny by the
late morning hours and into the afternoon, with comfortable
temperatures and low humidity. Highs will mainly be in the 70s
Dry weather will be short-lived, as the surface high pressure
will exit to the east. The next storm system will be a frontal
system approaching from the Great Lakes and southern Canada, as
a shortwave trough passes by to the north of the area for Wed
night into Thursday. Some showers and thunderstorms will be
possible, especially right along the approaching surface
boundary. Best chance will be across northern areas, which will
be closer to the upper level dynamics. Based on expected amounts
of instability, have included thunder within the diurnally
favored afternoon and evening hours. Highs on Thursday look to
reach into the upper 70s for most areas, with dewpoints creeping
back up through the 60s.
The front looks to cross through the area for Thursday night
into Friday morning, which should be ending the threat for
rainfall. With surface high pressure nosing down into the area
from southern Canada, the front should drop far enough south to
keep any rain on Friday across the mid-Atlantic states, which is
a change in the models from other recent runs. Will continue to
monitor model trends, but it appears (at this point) that our
area should be staying dry to end the week with highs mainly in
the 70s on Friday.
Long term /Friday night through Tuesday/...
high pressure begins to build in Friday night with decreasing cloud
cover, especially in northern areas. The upper pattern becomes
complex through the weekend with an increasing consensus that an
upper low develops south of our region late Friday and tracks south
of Long Island Saturday and Saturday night. Most sources of guidance
and ensembles keep the deeper moisture and most of the extensive
cloud cover just south of our region. However, the northern extent
of clouds and isolated showers could get into the Mid Hudson valley
and northwest CT Friday night and Saturday before the high pressure builds
into our region from Canada and the Great Lakes. Highs Saturday in
the mid to upper 70s but cooler in higher terrain.
Mean upper troughing remains just east of our region Sunday and
Monday with some upper ridging building east from the Great Lakes
north of the exiting upper troughing. The upper ridging will aid in
some slow gradual warm advection. So, dry weather and more sun than
clouds Sunday and Monday as long as upper troughing does exit just
to the east as guidance suggests. Highs Sunday in the upper 70s to
around 80 but lower 70s higher terrain. Highs Monday in the lower to
mid 80s but mid to upper 70s higher terrain.
By Tuesday there is a loose consensus for the next weak cold front
to drop south out of Canada with little moisture and weak low level
forcing. So, intervals of clouds and sun with isolated to scattered
showers and thunderstorms. Highs Tuesday in the lower to mid 80s
but mid to upper 70s higher terrain.
Aviation /02z Wednesday through Sunday/...
high pressure is gradually building in from the north and a
clearing sky is building in from the north and east. Lingering
low level moisture is keeping MVFR ceilings in the kalb, kpsf
and kpou areas but the sky is improving into the VFR range at
kgfl. Based on the slow and gradual clearing trend from the
west, timing ceilings rising to VFR and becoming scattered at
kpsf, kalb and kgfl around or just before daybreak, with kpsf
and kgfl seeing the ceiling breakup first. There could be a
brief period of MVFR fog at kpsf and kgfl if the clearing occurs
early enough. Kpou may not see the break in the ceiling until
just after daybreak.
Once the ceilings have gone, just scattered clouds above 3000
feet the rest of Wednesday morning and afternoon. Light north to
east winds at less than 6 kt will become nearly calm tonight.
Winds become south at less than 10 kt Wednesday morning and
Wednesday night: low operational impact. Slight chance of rain showers.
Thursday: moderate operational impact. Chance of rain showers...tsra.
Thursday night: moderate operational impact. Chance of rain showers...tsra.
Friday: low operational impact. Slight chance of rain showers.
Friday night: no 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.
no fire weather related issues expected, as our area saw a
wetting rain yesterday into last night. Relative humidity values will fall to
40 to 70 percent on Wednesday with very light winds. The next
chance for rain showers and thunderstorms will be on Thursday.
mainly dry weather is expected tonight into tomorrow with clouds
breaking for some sunshine on Wednesday. The next frontal system
will return the chance for some showers and thunderstorms on
Thursday into Thursday evening. Model guidance is starting to
come together that it should be through by Friday morning, so
dry weather looks to return for Friday into the weekend.
Rainfall amounts will be variable on Thursday due to the track
of showers/thunderstorms, but widespread heavy rainfall is not
expected. Aside from a brief burst of heavy rainfall from a
thunderstorm, no flooding issues are anticipated with this
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.