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Area forecast discussion 
National Weather Service Albany New York
1035 am EDT Thursday Sep 3 2015

Synopsis...
a weak cold front will track across the region today. This will be
the main focus mechanism for isolated to scattered showers and
thunderstorms today...with the best probabilities across the
terrain. Thereafter...high pressure builds across the region for
the Holiday weekend with mainly dry conditions and above
seasonable temperatures.

&&

Near term /through tonight/...
as of 1025 am EDT...no shower activity noted on area radars and
any cloudiness over the region showing little vertical extent. As
a result...have removed any chance for showers for the rest of the
morning...but left the probability of precipitation for the afternoon as they were. Much
of the forecast area still sunny or mostly sunny...and have
lowered the amount of cloudiness in the sky cover grids for the
rest of this morning and early afternoon.

Previous disc...
during the afternoon...the combination of relatively high low
level moisture and the approach of the weak cold front will allow
for low level convergence to increase and for some convection to
develop. Latest NCEP model suite offer quite a different approach
to the amount of instability across the region with the NAM
remaining the highest with sbcapes climbing in excess of 2k j/kg.
The GFS is about half as much which is in closer agreement with
the hourly mesoscale updates from the rap13/hrrr. This is likely
the culprit of the forecast surface dewpoints as upstream values were
currently in the middle 60s as opposed to the NAM with values close
to 70f. As for lapse rates...modest values seen in the bufr
profiles with an average 6.5-7.0 c/km within the h850-500 layer.
Yet the wind shear is less than ideal for organized convection
with values 20kts or less. Per Storm Prediction Center coordination...general
thunderstorm threat and per those soundings...could not rule out
1-2 events across the region as the combination of inverted-v type
soundings and precipitation loading convection could result in an
isolated downburst.

Temperatures remain above normal once again but slightly cooler
than wednesdays highs due to the aforementioned cloud coverage
and the chance for precipitation with mainly middle 80s for valley locations
and 70s for the terrain.

Tonight residual convection should dissipate as surface
anticyclone builds in from northeast Canada. Trends in the model
suite suggest low level moisture from the east-northeast trajectories along
with upslope conditions into The Greens...Berks and northwest CT and slow
movement of the frontal movement south of i90 could keep clouds a
bit longer and perhaps an isolated shower. MOS values overnight
are very close and a blended approach was utilized. Fog potential
is not that clear at this time as we watch the potential for
stratus development.

&&

Short term /Friday through Saturday night/...
Friday...still some question just how much low level stratus will
be across the region as the GFS is more aggressive than the NAM.
However...they both agree the weakening frontal boundary may get
hung up along the i84 corridor where we will keep the slight
chance probability of precipitation at this time along with additional cloud coverage.
Otherwise...breaks in the cloud coverage and as h925-850 cool off
from the east-northeast into the lower teens...this should yield even cooler
afternoon highs with near 80f for valley locations with mainly 70s
for the entire County warning forecast area.

Friday night...a pleasant evening is expected with gradual clearing
to mostly clear skies and calm winds...as the surface high moves over
New York and New England. Ideal radiational cooling conditions will
occur...and lows will be mainly in the lower to m50s with a few
u40s in the southern dacks. Some patchy or areas of radiational fog may
form...and may need to be added to the forecast later in time for more
widespread fog.

Saturday...a good deal of sunshine as temperatures will be slightly
warmer than Friday with a middle and upper level ridge building in
over the northeast. A closed anticyclone may set up over New York and
New England late in the day. H925-850 temperatures rebound back into the
middle teens celsius along with increasing subsidence with the middle
and upper ridge...and the surface anticyclone for 80s in the valleys
and 70s for the terrain.

Saturday night...big bubble...little trouble as the combination of
clear skies...calm winds and longer nocturnal period should allow
for radiational fog to form once again and could be even more
widespread. This will continue to be monitored and evaluated in
later forecasts. Lows mainly into the 50s for the region.

&&

Long term /Sunday through Wednesday/...
the long term portion of the forecast will feature above normal
temperatures and below normal precipitation...continuing the trend
from the short term.

A ridge of high pressure at all levels of the atmosphere will
provide the dry and very warm conditions through at least Labor Day.
500 mb heights and 850 mb temperatures are forecast to be +1 to +2
stdev according to the gefs which will result in middle level capping
suppressing convection with plenty of sunshine. Normal high
temperatures for Albany by early next week will be the middle
70s...however we will experience temperatures in the middle to upper
80s...with some temperatures possibly approaching 90 in portions of the middle
Hudson Valley by Monday. Overnight low temperatures should fall into
the 50s to lower 60s for Monday am...then mainly Lower/Middle 60s for Monday
nt/Tuesday am although some 50s could still occur in portions of the
Adirondacks and eastern Catskills...as well as portions of the
southern greens and in the Berkshires. Humidity levels should remain
somewhat comfortable through Monday.

The next chance of any precipitation arrives on Tuesday as a
weakening frontal boundary approaches from the north and west.
Latest models suggest that this front weakens quite a bit before
reaching our region...as the best upper level support shears well north
and west of the region. This energy should flatten out the upper level
ridge a bit. Will only include some slight chance to low chance probability of precipitation
for the Adirondacks for late Tuesday...and slight chance Tuesday nt into Wednesday
for mainly the northern half of the region. Tuesday maximum temperatures should
still reach the middle/upper 80s for most areas...except for lower 80s
across higher elevations. Only slightly cooler conditions will occur
behind the front...leaving well above normal readings to persist.
Overnight mins for Tuesday nt/Wednesday am should fall into the Lower/Middle
60s...except for 50s across some higher elevations.

There are some indications that a stronger cold front may approach
the region late next week...but this remains uncertain. For now...
above normal temperatures can be expected to continue through the
next 7-10 days.

&&

Aviation /15z Thursday through Monday/...
a weak cold front will settle southward across the taf sites this
afternoon/early evening. Isolated showers/thunderstorms will be
possible with or just ahead of this front.

Areas of low clouds/fog should dissipate at kgfl and kpsf between
12z-14z/Thu. Thereafter...VFR conditions are expected...outside
of isolated showers/thunderstorms which should develop between
18z- 22z/Thu. Most of the convection is expected to remain west
and east of the taf sites...but can not rule out a couple
impacting the taf sites later this afternoon. Brief periods of
MVFR/IFR visibilities could occur within the cores of any
showers/thunderstorms.

Convection should decrease after 00z/Fri...with mainly VFR
conditions continuing through 06z/Fri.

Some low clouds may develop and/or spread westward between 09z-
12z/Fri...especially at kpsf and kpou. Generally MVFR ceilings will be
possible...although kpsf could approach IFR ceilings.

Light/variable winds should persist through 13z/Thu...then trend
into the north to northwest at 5-10 knots this afternoon. Winds will
then shift into the north to NE between 01z-04z/Friday in the wake of the
cold front...at 5-10 knots...although could briefly gust into the
10-20 knots range...especially at kgfl due to channeling down the upper
Hudson/Champlain Valley and Lake George.

Outlook...

Thursday nt-labor day: no operational impact. No sig weather.

&&

Fire weather...
our recent dry weather...and more expected in the
forecast...continues to be monitored. However...low level moisture
remains elevated and with the approach of a weak cold front could
touch off isolated to scattered showers and thunderstorms later
this morning into the afternoon hours. Most of this activity
should dissipate for the region tonight but a shower or two may
linger south of i90 into Friday.

The relative humidity values will fall to 45-60 percent this afternoon. An
excellent recovery is likely Friday morning with maximum relative humidity values
once again of 90 to 100 percent.

The winds will be light and variable in direction this morning.
The winds will then shift to the northwest to north at 5-15 miles per hour
this afternoon...and then will become north to northeast at 5 to
10 miles per hour by this evening.

&&

Hydrology...
no Hydro problems are expected the next 5 days ending Labor Day.

Isolated to scattered showers and or thunderstorms will be
possible today...as a backdoor cold front moves southward across
the region....otherwise it will be dry through the period.

Rainfall amounts may range from a tenth to quarter inch with
locally higher amounts from any thunderstorms.

Above normal temperatures will continue through the
Holiday weekend...as high pressure dominates. River flows will
remain below normal for early September.

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.

&&

Aly watches/warnings/advisories...
CT...none.
New York...none.
Massachusetts...none.
Vermont...none.

&&

$$
Synopsis...bgm
near term...gjm/bgm
short term...bgm/wasula
long term...kl/jpv
aviation...kl
fire weather...bgm/wasula
hydrology...bgm/wasula

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