Scientific Forecaster Discussion
Area forecast discussion...corrected
National Weather Service Albany New York
415 am EDT Sat Aug 30 2014
high pressure will move east of New England overnight... with a
return southerly flow of more humid air moving into the region
Saturday. A disturbance moving along a cold front will bring showers
and thunderstorms on Sunday. Weak high pressure is expected to build
into the region Monday but isolated showers and thunderstorms are
still possible as a humid airmass will be over the region.
Near term /until 6 PM this evening/...
as of 415 am EDT...patchy clouds...associated with warm air
advection have moved through the region. IFR satellite pictures
indicated that clouds have thinned again once more.
A south to southeasterly breeze has ensued across portions of the
Hudson and Mohawk valleys as well as most of the higher terrain to
the west of the Hudson Valley. As a result in these
areas...temperatures have held close to 60 degrees. Further north
and east...the surface wind has remained nearly calm and with a
clearing sky once more...temperatures have dipped down well into the
By daybreak...look for lows ranging in the 50s throughout the region
with a mainly clear sky. There will be some patches of fog mainly in
sheltered areas from the wind...but that will the exception and not
A south to southeast wind will pickup through the area this
morning...averaging 10-15 miles per hour by afternoon. Some high and middle level
clouds will occasionally dim the sun...but it should remain dry.
High temperatures will get close to 80 through the area...so a
little warmer than Friday. Dewpoints will be in the middle to upper
50s...so still not all that humid.
Short term /6 PM this evening through Monday night/...
as of 400 am EDT...the h20 water vapor loop indicated a rather
potent middle level disturbance over Minnesota. This system will advect
eastward and move into our northern areas on Sunday. At the same
time...a weak cold front will traverse into the area as well Sunday.
Ahead of it...an elongated upper level trough will pull very moist
air from the Gulf states...and our precipitable water values will increase to
about 2 inches.
This should set the state for numerous showers and scattered
thunderstorms. These will begin to move into our area by sunrise
Sunday...and while Sunday might not necessarily be a washout...the
threat of rain will there throughout the day.
It looks as if clouds should limit instability...although it could
easily reach 1000 j/kg. However...if we receive more sunshine than
we are currently forecasting...that number could increase a lot
which would in turn increase the potency of thunderstorms. Right
now...middle level lapse rates look modest at only around 5.0 c/km.
However...the 0-6 km bulk shear looks to increase to about 35kts.
So...right not...the threat of severe thunderstorms looks slim (but
possible). The better bet is that any thunderstorm could contain
heavy rainfall so we will continue enhanced wording ("thunderstorms
might contain heavy rainfall") Sunday into Sunday evening. We will
continue to monitor.
Sunshine or not...the humidity will markedly increase on Sunday with
dewpoints climbing through the 60s...possibly touching 70. High
temperatures will range from the middle 70s across our Adirondacks...to
near 80 locally in the capital region...up to the middle 80s south of a
Sunday night...the aforementioned disturbance will exit off to the
east. The trailing front could lie down in our southern areas. While
further weakening is expected...it might be just enough of focus for
additional showers and thunderstorms to develop mainly on Labor Day.
The best chance of these will be south of the capital region. We
will continue with slight chances of showers and storms capital
region northward...low chances (30 pops) south of the capital
There should be more sunshine on Monday. As result...temperatures
look quite warm (with h850 temperatures prognosticated around +16c) surface
high temperatures will climb well into the 80s across most places
making it feel quite summery...especially since dewpoints will
remain elevated in the middle to upper 60s.
It will be muggy Monday night with a continue chance for an isolated
shower or thunderstorm and lows in the 60s.
Long term /Tuesday through Friday/...
except for a frontal passage that occurs Tuesday afternoon and
night...the long term period will feature high pressure over the
region along with above normal temperatures and little or no precipitation
Wednesday through Friday.
Have forecast probability of precipitation to increase by Tuesday afternoon to likely
values over the Adirondacks and western Mohawk Valley...ranging to
only low chance values (30 to 35 percent) over the middle Hudson Valley
and Litchfield County. For early Wednesday night probability of precipitation are forecast
to be in the 35 to 50 percent range across the entire forecast
area...then decrease to dry levels (14 percent or less) by sunrise
Generally dry weather is then forecast for Wednesday through
Friday...with the exception of a slight chance of showers or thunderstorms
late Friday afternoon over the Adirondacks and most of the Mohawk
and Schoharie valleys...due to another frontal system approaching
from the west.
Temperatures will be above normal during the long term period. Highs
Tuesday will be in the upper 70s and 80s. Lows Tuesday night in the
60s. A little cooler thereafter...but still above normal. Highs
Wednesday through Friday in the middle 70s to middle 80s. Lows Wednesday
and Thursday nights in the 50s to lower 60s.
Aviation /07z Saturday through Wednesday/...
patchy low/middle level clouds and a southerly breeze in some areas has
put a hold on fog formation thus far tonight. As a result...will
only forecast occasional IFR fog at kgfl/kpsf between 07z and 11z.
At kalb/kpou...occasional light south winds at kpou...and a decent
breeze around 10 kts at kalb will prevent IFR fog formation at these
locations. In fact...have not forecast any fog at kalb.
Any fog that does form at kgfl/kpsf should be gone by 11z/12z
Saturday...then expect VFR conditions at all the taf sites through
the end of the taf period at 00z Sunday.
Surface winds will be generally calm at kgfl/kpsf through a little
after sunrise...south at kalb between 5 and 10 kts...and light
south (under 5 kts) at kpou. After sunrise south winds will pick up
at all locations to between 5 and 10 kts...with some gusts to 15 kts
Saturday night: low operational impact. Isolated rain showers...tsra.
Sunday: high operational impact. Likely rain showers...tsra.
Sunday night: moderate operational impact. Scattered rain showers...tsra.
Labor day: low operational impact. Isolated rain showers...tsra.
Monday night: low operational impact. Slight chance of rain showers...tsra.
Tuesday: moderate operational impact. Chance of rain showers...tsra.
Tuesday night: moderate operational impact. Chance of rain showers...tsra.
Wednesday: no operational impact. No sig weather.
high pressure will move offshore today...with a return southerly
flow of more humid air moving into the region. A disturbance moving
along a cold frontal boundary north of most of the region will bring
showers and thunderstorms Sunday into Sunday evening. Weak high
pressure is expected to build into the region Monday but isolated
showers and thunderstorms are still possible as a humid airmass will
still be over the region.
Minimum relative humidity values should be between 45 and 55 percent Saturday and
65 to 75 percent Sunday. Maximum relative humidity values tonight are expected to be
80 to 100 percent with some dew formation tonight and tomorrow night.
The surface wind be south to southeasterly 5-15 miles per hour today with some
higher afternoon gusts to around 20 miles per hour. These winds will continue
through Sunday...becoming lighter Sunday night into Monday.
it will be dry today and most of tonight.
Then...it looks as if showers and thunderstorms will develop late
tonight and especially Sunday into Sunday evening. Average basin
rainfalls look to generally be under an inch so at this point...main
stream rivers will generally see little or no rises.
However...with precipitable water values forecast to increase to 2 inches...any
thunderstorm could contain locally heavy rainfall easily exceeding
an inch. Any training thunderstorms could result localized ponding
of water in areas of poor drainage...possibly even leading to
localized flash flooding.
If confidence in this scenario increases...a Flash Flood Watch might
issued later today for a portion of our area for Sunday.
Additional thunderstorms on Labor Day look isolated and generally
not expected to produce additional Hydro problems.
More showers and thunderstorms are possible late Tuesday into
Wednesday as a stronger cold front arrives.
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.