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Area forecast discussion 
National Weather Service Albany New York
113 PM EDT Thursday may 28 2015

Synopsis...
a weak cold front will track through the region with scattered
showers and isolated thunderstorms through this afternoon. Weak
high pressure will build over New York and New England into
Friday...before sliding offshore Friday night. Warmer and more
humid air will return to the region Saturday. A cold front will
drop slowly southeast through the region Saturday night and
Sunday...and stall to our south Monday. It will bring more showers
and thunderstorms and cooler weather for the new week.

&&

Near term /through tonight/...

..Severe Thunderstorm Watch 233 in effect until 7 PM EDT from
Albany and points S and east into western New England...

As of 110 PM EDT...the cold front extends southeast Washington
Colorado...to just east and south of kalb...into east central Greene and
Ulster cos. Isolated showers have formed along or just ahead of
the boundary...but thus far...no cloud to ground lightning noted.
However...as the front continues moving S and east over the next few
hours...it will encounter greater instability...as latest Storm Prediction Center
mesoanalysis suggests sb convective available potential energy in the 1500-2000 j/kg range across
the middle Hudson Valley...northwest CT...Berkshires...and extreme southern
Vermont. It is in these areas that a threat for isolated severe
thunderstorms remains...at least through around 3 PM.
Thereafter...the threat should diminish. Damaging wind gusts would
be the main threat from any thunderstorms.

For areas north and west of the front...although an isolated shower could
still occur as the upper trough passes...the threat for any deeper
convection looks minimal at best.

Also...much cooler and less humid air is infiltrating the Mohawk
Valley and Adirondacks in the wake of the front...where temperatures have
fallen into the upper 60s to lower 70s. We expect temperatures to fall
off several degrees from pre-frontal temperatures this afternoon...so
after briefly reaching the lower to middle 80s in some lower
elevations...temperatures will likely fall back into the 70s for most
areas this afternoon...with some lower 70s possible in the Mohawk
Valley region. Higher elevations across the southern Adirondacks
will likely only remain in the 60s through this afternoon...with
some of the highest peaks possibly holding near 60.

Winds will increase from the west to northwest in the wake of the
front...increasing to 15-25 miles per hour...with some higher gusts possibly
reaching up to 30-35 miles per hour.

Skies will clear quickly late this afternoon and evening...with mainly
clear to clear skies forecast overnight. It will be cooler and
less humid tonight with lows in the upper 40s and 50s.

&&

Short term /Friday through Sunday night/...
Friday 500hpa heights/ridge briefly build over region and slide
offshore...as surface high pressure builds over region under it...before
sliding offshore. Another fine Summer day as high temperatures reach the
low and middle 80s in most areas with upper 70s in the hir terrain.

Friday nt and Sat the ridge at all levels slides offshore and an increase
S-SW flow of increasing moisture advection sets up across the eastern
Seaboard. Dew point increase back into the 60s with variable to increase clouds.
During the day Sat models begin to diverge in timing both the
approaching cold front and the threat of tstms/shra. The European model (ecmwf)/Gem
hold the bulk of the precipitation threat off till late Sat...the NAM/GFS
bring threat into region by afternoon. Pvs forecast...HPC favored this slower
timing of precipitation threat and cold front and given its general parallel
nature to upper flow that looks reasonable. So Sat will be variable
cloudy...warm and humid with increasing chance thunderstorms.

Sat nt and sun most of the model suite brings a cold front slowly south
through the fca...but the scenarios begin spreading. The Gem
stalls it in the middle Atlantic with surface low in the Ohio Valley rippling east
along it...and clouds and -shra persisting into Monday. The
European model (ecmwf)/GFS moves it albeit slowly through fca with clearing implied
north of i90 corridor sun nt. Its southern extent will be determined
by very subtle variations in the 500hpa flow which remains largely
parallel to the baroclinic zone.

Regardless...after days of well above normal temperatures...temperatures will turn
well below normal sun...under clouds and cooler air advecting into
fca associated with surface high over ont/qb.

&&

Long term /Monday through Wednesday/...
generally a zonal flow over north tier of USA is replaced by a
building 500 hpa ridge. The GFS keeps MST of the energy in a
500hpa cut off over S miss valley...while the European model (ecmwf) brings some to
the region as a short WV across fca Tuesday.

At same time Monday surface front remains stalled S of fca...with threat
of rain showers and clouds across S tier. Bynd Monday most of the guidance takes
cold front far enough S as surface high pressure builds east across S ont/qb
and north New York state and new eng to allow for fair conds with a gradual
warming trend to set up. However this is a low confidence fca...as a
hundred miles one way or the other will result in sig changes to
the efp. Temperatures will begin period blow normal and end slightly above
normals.

Will pop grids with HPC with only minor changes.

&&

Aviation /18z Thursday through Tuesday/...
as of 12z...abundant low-level moisture resulted in widespread
IFR/MVFR ceilings across the kgfl/kalb/kpsf/kpou taf sites...these ceilings
could linger until around 14z and have included tempo groups at all
the taf sites for IFR ceilings (mvfr at kpou) between 12z and 14z.
Otherwise mainly VFR conditions expected at the taf sites through at
least midnight tonight. There will be a cold front moving through
the region during the afternoon. This cold front will produce
isolated to scattered thunderstorms...with the potential to produce strong
to possible severe wind gusts. However...due to the isolated to
scattered nature of the convection and difficulty pining down the
timing of possible convection at the taf sites...have only included
vcsh in the tafs at this time. After about 22z expect mainly clear
to clear skies through at least midnight...then have included the
potential for MVFR/IFR ceilings/visibilities due to the potential for fog
formation...especially at those locations that get precipitation this afternoon.

Winds will be light and variable or south to southwest at 8 kts or
less through 13z-14z...the winds should pickup to 8 to 12 kts...
then switch to westerly between 18z and 20z with gusts of 15 to 18
kts after that. After 00z winds will quickly diminish and become
light.

Outlook...

Friday: no operational impact. No sig weather.
Friday night: no operational impact. No sig weather.
Saturday: moderate operational impact. Breezy chance of rain showers...tsra.
Saturday night: high operational impact. Likely rain showers...tsra.
Sunday: moderate operational impact. Chance of rain showers.
Sunday night: low operational impact. Slight chance of rain showers.
Monday: low operational impact. Slight chance of rain showers.

&&

Fire weather...
for the first time in weeks most of fca has had over a quarter of
an inch of rain. Fire weather concerns should diminish through
this period.

Relative humidity values will drop to 45 to 60 percent this afternoon before returning
to near 100 percent tonight. They will fall to 30 to 45 percent Friday
afternoon. Winds will be light becoming south Friday afternoon
around 10 miles per hour.

Another front cold front will bring showers and thunderstorms for
late Sat into sun.

&&

Hydrology...
scattered showers are possible this morning with generally dry
conditions expected from this afternoon into Sat morning. Showers
and thunderstorms will return to the region late Sat into Sunday
as another cold front drops south through the region. Locally
heavy downpours will be possible and many areas could see a half
an inch to an inch of much needed rain.

&&

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

&&

$$
Synopsis...Snyder/NAS
near term...kl/gjm/NAS
short term...Snyder
long term...Snyder
aviation...gjm
fire weather...kl/Snyder/wasula
hydrology...kl/Snyder/wasula

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