Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Albany New York
159 am EDT Tuesday may 26 2015
it will be mainly dry tonight with a few showers scattered mainly
north of the capital region. A warmer and more humid air mass will
be across the region through most of the upcoming week. A series
of upper disturbances and frontal passages will bring about the
chance for showers and thunderstorms. Some of these storms will
have the potential to produce heavier rainfall.
Near term /until 6 am this morning/...
batches of showers continue to move across the northern most
portion of the forecast area. Guidance shows this activity will
diminish before sunrise so have probability of precipitation lowering to slight chance.
Have also adjusted overnight lows based on observational data.
Now have lows in the 60s except for some upper 50s across a
portion of the eastern Catskills and western Adirondacks.
Short term /6 am this morning through Wednesday night/...
a warm and muggy air mass across the entire region through through
the short term with an increasing chance for showers and
thunderstorms. The aforementioned Theta-E axis is expected to be
along or south of i90 where we will retain the chance-scattered probability of precipitation. This
boundary is forecast to lift northward through the day as the
chance for convection too will lift northward into Tuesday afternoon.
While some breaks in the cloud cover are expected...additional
clouds will fill in through the day with temperatures into the
lower half of the 80s for valley locations and upper 70s for the
terrain. Meanwhile...precipitable waters too will be on the rise with values
expected to be at or above 1.50 inches.
Moisture transport along with higher precipitable waters arrive in advance of a
pre-frontal boundary on Wednesday. This is where the best
potential will exist for deeper convection. As noted in the
previous discussion...Storm Prediction Center continues to place our region in a
marginal category with decent linear shear profiles with
magnitudes around around 30kts...sbcapes between 2-3k j/kg but
marginal middle level lapse rates of around 6c/km. Precipitable waters are prognosticated
to continue the upward climb with NCEP model suite suggesting
values approaching 2 inches which would be 2-3 Standard deviations
above normal. So the potential remains of moderate to heavy
rainfall as the current severe weather potential statement remains in excellent shape.
Temperatures through the period will be above normal with mainly
80s for valley locations and 60s for overnight lows.
Long term /Thursday through Monday/...
Thursday through Friday night...a very hazy hot and humid airmass
continues to be anchored over the region as the latest 25/12z global
model and probabilistic data continues to show a large surface high
pressure and a broad 500 hpa high pressure over the North Atlantic
providing a southwesterly flow bringing warm and humid air into the
region. This stacked anticyclone will slowly drift to the east south
of the Canadian Maritimes by Friday night which will allow a rather
large synoptic system upstream to move into the region by the
weekend. For Thursday and Friday...diurnally triggered thunderstorms
will be main focus of precipitation with scattered to chance probability of precipitation
over the region to indicate uncertainty in pop-up storm activity.
High temperatures on Thursday and Friday will range from the upper 70s in
the high terrain to lower and middle 80s for valley locations.
Saturday through Monday...a distinct frontal boundary will move its
way across the Great Lakes area and into our region as we go into
the afternoon and evening hours on Saturday. A developing and
deepening of an upper level trough axis over northern Ontario will
move eastward into Quebec as we go into Saturday night. A surface
low pressure system will develop over Canada with a trailing cold
front over the northern tier Continental U.S.. as this noticeable baroclinic
zone works eastward...showers and thunderstorms may become more
numerous as we head into Saturday afternoon. In-conjunction with
the frontal system...latest 25/12z data also indicate a developing
120 knots 250 hpa jet over southern Quebec by Saturday night. With our
region in the right entrance region of the jet with upper level
divergence...there is the chance of some widespread thunderstorms
over the region. Model guidance does differ in timing and intensity
with the frontal passage and quantitative precipitation forecast amounts but we will continue to
monitor this potential active weather event and update accordingly.
High temperatures ahead of the front on Saturday will range from the
u70s to l80s in the high terrain with u80s to near 90 in the middle
Hudson Valley areas. The front will be through the entire region by
Sunday afternoon with high temperatures on Sunday and Monday closer
to average with high in the middle 70s. There remains a chance of an
isolated shower as the exact timing of the frontal passage between
the latest 12z data is not at high confidence at this time.
Aviation /06z Tuesday through Saturday/...
a warm front has lifted north of the forecast area into northern New
England and southern Quebec. Most of the forecast area will be in a
warm sector with high pressure over the western Atlantic Ocean today
Middle and high level clouds prevail for kgfl/kalb/kpsf/kpou this
morning with VFR conditions. A few showers may get close to kgfl so
a vcsh group was used. The clouds will thin late this morning with
mainly some high clouds around with scattered-broken cumulus for the PM.
Some pop-up showers or thunderstorms may develop by the middle to late
PM in the humid air mass. Vcsh groups and ceilings bkn050-060 were
Confidence was not high enough to place prob30 groups in for
thunderstorms. Middle and high clouds will linger into the overnight
The winds will be from south at 5-12 kts this morning with some
gusts around 20 kts at kalb/kpsf. The winds will continue from the
S to SW at 10-15 kts with some gusts close to 25 kts at kalb/kpsf in
Tuesday night through friday: moderate operational impact. Chance of
rain showers...tsra...mainly during the afternoon and evening hours.
Friday night...low operational impact. Slight chance of thunderstorms and rain.
Saturday...moderate operational impact. Chance of rain showers...slight
chance thunderstorms and rain.
warm temperatures and increasingly humid conditions are forecast
for this week with chances for showers and thunderstorms...
especially middle week.
Relative humidity values tonight recover between 70 and 90 percent tonight...then
expected to range between 40 and 60 percent Tuesday afternoon
with values between 50 and 70 percent Wednesday afternoon.
The better chances for thunderstorms will be during the afternoon
into early evening hours.
no widespread Hydro problems expected this week...however
thunderstorms will be capable of producing heavy downpours.
The U.S. Drought monitor has now included much of eastern New York and
western New England in the d1 category...which is considered
It will turn warm and humid this week and there will be chances
for showers and thunderstorms especially middle week. Precipitable
water values are forecast to rise to over 1.5 inches so storms
will be capable of producing heavy downpours. The best potential
will be during the middle week period.
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