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Area forecast discussion 
National Weather Service Albany New York
725 am EDT Thursday may 28 2015

Synopsis...
an upper level disturbance will cross the region this morning
with scattered showers and isolated thunderstorms. High pressure
will build over New York and New England this afternoon into
Friday..before sliding offshore Friday night. Warmer and more
humid air will return to the region to start the weekend. 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/...
as of 400 am EDT...the main cold front...and upper level trough
were entering western New York. There was a band of scattered showers
ahead of these features that stretched from the Tug Hill plateau
to near Syracuse to north-central Pennsylvania. With enough
heating ahead of the band of showers...thunderstorms will also develop
along this band by late this morning or early afternoon. The
showers from this band will likely reach the extreme northwest
part of the forecast around sunrise...with the axis of this band
reaching a line from Lake George to the capital district to the
eastern Catskills around noon...then from southern Berkshire
County to the southern Taconics and Litchfield County 3-4 PM.
By sunset...all showers/thunderstorms will have exited the Albany
forecast area. Expect the showers/thunderstorms along this band to remain
scattered...so have forecast no higher than chance probability of precipitation in any
part of the forecast area. Highs today will be in the upper 60s
over the western Adirondacks...and the 70s to middle 80s elsewhere.
Winds will shift from south or southwest to west or northwest
during the day as the cold front moves through with wind gusts of
20 to 25 miles per hour possible.

The storms prediction center (spc) has placed a small portion of
east central New York...southern Vermont and Berkshire County in a slight
risk of severe thunderstorms for today...with much of the rest of the
forecast area (except for the northwest third)...in a marginal
risk. Will update the zones to reflect this outlook.

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 /12z Thursday through Monday/...
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
near term...gjm
short term...Snyder
long term...Snyder
aviation...gjm
fire weather...kl/Snyder/wasula
hydrology...kl/Snyder/wasula

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