Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Albany New York
450 am EDT Monday Apr 21 2014

Synopsis...
high pressure will continue to dominate our weather today as it
moves further offshore. Showers will overspread the area Tuesday
morning and continue into the evening hours as a low pressure system
and its associated cold front approaches and moves across the
region. Cooler air will be ushered in behind this system for middle
week.
&&

Near term /until 6 PM this evening/...
as of 445 am EDT...many surface observations in our forecast area
still indicate a southeast breeze still happening in the range of 5
to 10 miles per hour. This breeze has kept temperatures from falling a whole
lot during the past several hours and high clouds have also
prevented radiational cooling. In fact...Glens Falls was milder than
Albany! (Alb/44 versus gfl/47).

In our south and eastern zones...the wind has decoupled and the sky
was the clearest. This has allow these areas to into the lower and
middle 30s.

High clouds were streaming across mainly our northern areas but
everyone was dry.

Through sunrise...look for temperatures to fall another couple of
degrees and it will remain dry with a clear to partly cloudy sky...
except mostly cloudy up north of Glens Falls. A few spots south and
east of Albany could dip just below freezing...but most areas will
bottom out between 35 and 40 degrees.

Today looks like another fine Spring day. There will be more high
clouds around than yesterday and the breeze out of the south will be
slightly stronger, averaging 10 to 15 miles per hour with some gusts this
afternoon approaching 25 miles per hour. Temperatures look milder than Sunday.
They are projected to reach 65 to 70 degrees across most of our
forecast areas...with some of the higher terrain 60-65 degrees.

&&

Short term /6 PM this evening through Wednesday night/...
as of 445 am EDT...low pressure was located over northern Minnesota. Its
frontal boundaries extended to its east across the eastern Great
Lakes...southward into the Ohio Valley.

This system will slowly head east. By tonight...it will spread a few
more clouds into our region but all areas will likely remain dry. A
southerly breeze should be even more persistent than tonight...which
will keep temperatures from falling below the 40s in most
place...generally in the 40-45 range.

Tuesday...the system will cross into our area. Precipitable water values look to
briefly spike to nearly an inch as a low level jet increases. A
pretty sharp low level convergence signature should help wring out
this moisture as showers develop. We continue with categorical
probability of precipitation...mainly for the afternoon right ahead of the cold front
feature.

We checked instability parameters and most models indicated little
or no instability. For now...we will exclude any mention of
thunder...but later forecasters might decided to add thunder at some
point.

High temperatures Tuesday look similar to today/S...60s to around
70...with some upper 50s across the Adirondacks.

The wind ahead of the cold front will be southerly 10 to 20
miles per hour...shifting to the west by day/ end with some higher gusts.

Cooler air pours back into the region Tuesday night and Wednesday.
H850 temperatures which will crest near +10c ahead of it...will drop
to about -5c by midday Wednesday. A few leftover showers behind the
front could actually change to snow showers across higher
elevations. At this point...any snowfall accumulations look very
light and confined to the Adirondacks where an inch or less could
accumulate.

Overnight lows on Tuesday night will back to the 30s across the
higher terrain...40-45 in most valley areas. Highs on Wednesday with
a gusty west wind will be 50-55 in most valleys areas (upper 50s middle
Hudson Valley and lower litchfield)...but only 40s across the higher
terrain.

As low pressure slowly moves from the Gulf of Maine...Wednesday
night still looks breezy. This breeze will prevent of free-fall of
temperatures but it will turn chilly nevertheless. Look for
overnight lows under a clear to partly cloudy sky to be in the lower
30s most valley locations...20s across the higher terrain. The
breeze will make it feel colder.

&&

Long term /Thursday through Sunday/...
we begin the period with a rather progressive northern branch of the
westerlies which transitions toward higher amplitude blocking across
noam toward the end of the weekend. This will keep the threat for
showers /even some snow potential for the terrain/ as temperatures
begin near normal and then shade cooler than normal by the end of
the weekend.

As for specifics...
a ridge both at the surface and aloft will provide a seasonable day
for the region with some increase in higher and some middle level cloud
cover later in the day. As a good deal of late April sunshine is
expected and h850 temperatures moderating from negative single digits to
around 0c by days end...majority of the area should climb into the
50s with around 60s for the middle Hudson Valley.

As the upper air pattern across the northern plains begins to
exhibit signs of becoming cut off from the main westerlies...its
attending cold front /transitioning toward occlusion/ will be
approaching Thursday night into Friday. As per the previous
forecast...we will gradually increase probability of precipitation from west to east with
mainly rain showers as the boundary layer appears too warm.
Overnight lows average in the 40s with daytime highs into the 50s
and lower half of the 60s for valley locations.

Friday and into the weekend...the global models begins to show
deviations as the upper pattern becomes higher amplified and rather
blocky. Transitions into these synoptic flows are problematic for
models as we attempt to ascertain individual short waves that will
impact our weather. The GFS wants to develop a cut off low over New
England as well as the previous run of the dgex. The European model (ecmwf) is much
more progressive with the passage of the frontal system and colder
air advects into the region with a return to sub zero h850 temperatures.
Wpc seems to follow this idea as we too will lean in this
direction. With still a cyclonic flow aloft...the chance for some
wintry type precipitation will exist across the higher terrain mainly at
night with lows dipping back toward freezing. Daytime highs will
drop back into the 40s for the terrain and lower half of the 50s for
valley locations.

&&

Aviation /08z Monday through Friday/...
VFR conditions will continue through the entire taf period ending
at 06z Tuesday.

A light southerly wind overnight with few-scattered high and middle level
clouds...mainly north of the thruway.

During the day Monday...middle and high level clouds will slowly
increase and thicken during the day...with broken ceilings of 12-15 kft in
place by the afternoon hours for kalb/kgfl. Southerly winds will be
around 5-10 kts...with the highest speeds during the best mixing in
the afternoon/early evening hours.

Outlook...
Tue: high operational impact. Occasional rain showers.
Tuesday night: high operational impact. Likely rain showers.
Wed: low operational impact.Breezy.
Wednesday night: low operational impact. Breezy. No sig weather.
Thursday-Thursday night: no operational impact. No sig weather.
Fri: moderate operational impact. Scattered rain showers.

&&

Fire weather...
most of our entire region is snow free now (except for some patches
of snow still left in the Woods of the Adirondacks and southern
greens).

Relative humidities will be low again this afternoon with minimums
in the 20s...

Relative humidity values are expected to recover to 60 to 80
percent tonight. Minimums values are expected to be in the 20s
Monday afternoon...with a recovery to 75 to 95 percent Monday
night.

The winds will be south or southeast today 10 to 15 miles per hour...with a few
higher gusts. A south wind will be 5 to 15 miles per hour tonight then increase
back up to 10 to 20 miles per hour on Tuesday.

Showers will overspread the area by midday Tuesday...then continue
into the evening hours as a low pressure system approaches and moves
across the region. Most areas look to receive a quarter inch or more
of rainfall.

Wednesday will be breezy with a wind out of the northwest as low
pressure very slowly moves to our east.

&&

Hydrology...
the Flood Warning for the Schroon river at riverbank continues.
The forecast has been consistent and it is expected to drop below
flood stage today sometime after 2 PM.

Dry weather will continue to dominate our weather through tonight.

Showers are expected to overspread the area by midday Tuesday
..then continue into the evening hours as a low pressure system
approaches and moves across the region. Generally quantitative precipitation forecast amounts of a
quarter to a third of an inch are expected with locally higher
amounts possible.

This rain will only bring minor within bankfull rises on some rivers
and streams.

Dry weather returns on Wednesday.

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...iaa/hwjiv
near term...hwjiv
short term...hwjiv
long term...bgm
aviation...frugis/bgm
fire weather...hwjiv
hydrology...iaa/hwjiv