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Area forecast discussion 
National Weather Service Albany New York
148 PM EDT sun Apr 19 2015

Synopsis...
high pressure will be in control of our weather today with lots
of sunshine and pleasant temperatures. However...a series of
weather systems will impact the region for most of next week
resulting in cool...damp...and unsettled conditions. We will begin
the week with a widespread rainfall Monday and Monday night.

&&

Near term /until 6 PM this evening/...
seasonably warm day with abundant sunshine and light winds.
Only made some minor adjustments were made to the forecast. Have
some thin cirrus clouds streaming in well in advance of the
approaching low pressure system as ridging over region gradually
weakens and shifts eastward.

&&

Short term /6 PM this evening through Tuesday/...
the aforementioned plains system will spawn a deepening surface
low and track across the Great Lakes region through the short term
period.

An impressive isentropic lift and strengthen moisture transport
advection will overspread the region from west to east tonight.
Clouds will quickly invade along with an increase probability for
showers/rain. The issue will be middle level dry air seen in the plan
view and forecast bufr profiles which will hold back the onset of
the precipitation initially. So the lower probability of precipitation will be east of the Hudson
River overnight with likely probability of precipitation expected west of the Hudson.
Furthermore...the low level southeast jet at or above 50kts
evolves which may result in brisk conditions across the higher
terrain. Temperatures and wet bulb processes for the dacks may see
some a wintry mix of rain/snow but no accumulation is expected at
this time.

This southeast wind per the wind anomalies will be significant
/4-5 Standard deviations above normal/ which may have
implications for the southeast Catskills on Monday. As seen in
many previous cases...this region will likely see enhanced
rainfall but per the NCEP model suite analysis...this feature will
be rather progressive limiting significant concerns. For the rest
of the region...a soggy day is expected. Where breaks in the
precipitation occur.

The strong eas-southeast winds could result in enhanced wind
magnitudes across the Berks and Taconics and western greens. So
have added mention in our hazardous weather outlook for this area
that a Wind Advisory may be needed if stronger wind gusts are
expected.

A little dry slot is prognosticated to move into the region late in the
day Monday into Monday early evening as the main moisture
transport advection slides east of the area. A more dynamic driven
upper wave coming out of the Ohio Valley and with the warm sector
will set the stage for another round of showers/convection. The
difference this time will be a little steeper middle level lapse
rates and middle level instability with showalters dropping back at
or below 0c for most of the region. In coordination with
neighboring offices and Storm Prediction Center...we will introduce a slight chance of
thunderstorms during the late evening into the early overnight
period Monday night into early Tuesday morning.

Tuesday...that wave passes quickly to our northeast leaving our
region well within the cyclonic flow yet most of the lift/dynamics
are upstream of the region. We will lower probability of precipitation to the chance
category with slight chance for the middle Hudson Valley and
northwest Connecticut. Highs Tuesday will fall generally between
55-65f.

&&

Long term /Tuesday night through Saturday/...
cool and unsettled weather is expected through the entire
extended period...as a large and slow moving trough settles in
over the northeastern US.

At the start of the extended period...a cutoff low will be situated
over the northern Great Lakes and slowly sitting and spinning in
place. Our region looks to be in a break from the large scale lift
for Tuesday night into Wednesday morning...so will only go with only lows
probability of precipitation. However...with the lowering heights and a few breaks in the
clouds...temperatures looks cool for Tuesday night with lows in the 30s. Highs
on Wednesday will reach well into the 50s for most areas...as there will
be a brief period of southerly winds ahead of an advancing surface cold
front.

This cold front will be associated with a piece of vorticity
swinging around the cutoff low for Wednesday afternoon into Wednesday night. A band
of rain showers will accompany this feature as it rotates across our
area for late Wednesday into Wednesday night. Behind this rainfall...temperatures look
to fall back into the 30s for most areas for Wednesday night with cloudy
conditions...as cooler air works into the region.

The cutoff upper level low will only slowly slide eastward across
Ontario into Quebec for Thursday into Friday...and then into
northern New England by Saturday. This will keep the cloudy and cool
conditions in place for the rest of the week...with a continued
slight to low chance for showers...especially for northern and high terrain
parts of the region. Upper level heights will be rather low with the
proximity of the upper level low nearby...and 850 hpa temperatures will
fall as low as -7 degrees c for northern areas. This may allow for
some of the precipitation to fall as wet snow at times...mainly for high
terrain areas during the late night and early morning hours. Valley
areas should remain just warm enough to keep precipitation as liquid...as
any precipitation will be fairly light in intensity...and won't be falling
hard enough to cool the column down fully in valley areas. High
temperatures for Thursday through Sat look mainly in the 40s to low 50s...and
lows will be in the 30s.

&&

Aviation /18z Sunday through Friday/...
VFR conditions will start
the taf period and by the end of the taf period...all taf sites will
change to MVFR/IFR conditions. A surface low pressure system moving
north over Michigan as we go into early Monday morning. Associated
with that surface low pressure system is a slow progressing warm
front that will move northeast toward all taf sites during the day
on Monday. Highest probability of rain for all taf sites will be
after 12z Monday through the end of the taf period. Rain will be
steady at times. Where breaks in the rain activity occurs...wind
gusts could be rather gusty....especially at kalb and kpsf. Visibilities
and ceilings will decrease as we go past 12z toward the end of the
taf period where MVFR/IFR conditions are expected.

Winds will be from the southeast between 5-10 knots with gusts over
20 knots at times...especially at kalb/kpsf.

Outlook...

Monday: high operational impact. Breezy. Definite rain.
Monday night: high operational impact. Definite rain.
Tuesday: moderate operational impact. Chance of rain showers.
Tuesday night: low operational impact. Slight chance of rain showers.
Wednesday-thursday: moderate operational impact. Chance of rain showers.

&&

Fire weather...
Haines index today at 5 today...

High pressure today will result in dry conditions and less wind
with minimum relative humidity values ranging between 20-30
percent.

Clouds increase through the day...and especially tonight with
showers/rain advancing from southwest to northeast overnight into
the day Monday. Relative humidities will climb to between 60 and
90 percent tonight.

A rainy day setting up for Monday to significantly reduce fire
weather related concerns. In fact...rather cool and unsettled
conditions will last through most of the upcoming week.

&&

Hydrology...
low probability for hydrology related concerns through the period.

Per the latest qpf/S...basin averages around one inch are expected
with up to one and one-half inches into the southeast Catskills
Monday into Monday night. Mmefs suggests a couple points may
approach or slightly exceed minor flood stage...Gilboa and
Hinckley dams.

The National operational hydrologic remote sensing center (nohrsc)
indicates that there is still a few inches of water equivalent in
the snow pack across the southern Adirondacks and northeastern
Berkshire County. Portions of the southern Green Mountains still
have 4 to 9 inches of snow water equivalent.

The rainfall combined with rises from ongoing snowmelt in the
above areas...may result in within bank rises Monday and Tuesday.

For details on specific area river and lakes...including observed
and forecast river stages and lake elevations...please visit the
advanced hydrologic prediction service /ahps/ graphs on our web-
site.

&&

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

&&

$$
Synopsis...gjm/bgm
near term...iaa/gjm/bgm
short term...iaa/bgm
long term...frugis
aviation...lfm
fire weather...bgm
hydrology...gjm/bgm

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