Scientific Forecaster Discussion

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Area forecast discussion 
National Weather Service Albany New York
945 PM EDT Wednesday Apr 16 2014

Synopsis...
Arctic high pressure will build into the region through tonight
with continued cold temperatures. Temperatures on Thursday will
moderate...but will still be below normal. High pressure will
dominate through Friday with tranquil conditions. Temperatures
will moderate further by Friday...with the next chance of rain
beginning the first half of the weekend.

&&

Near term /until 6 am Thursday morning/...
as of 930 PM EDT...very quiet weather across our region. Large
1040mb high pressure will build directly overhead. The sky will be
initially clear...wind light or calm...with perhaps a few cirrus
streaming in later tonight. Ergo...we will have near ideal
radiational cooling conditions.

For this update...only extremely minor re-tooling of the hourly
grids. Otherwise overnight lows look right in the ballpark.

Temperatures will drop quickly into the overnight period. Lows will
be well below normal with values ranging from the middle teens in the
high terrain to the lower 20s in the immediate capital region. We
are forecasting to tie a record low at Albany...which is 21 degree
set back in 1971.

&&

Short term /6 am Thursday morning through Friday night/...
high pressure will dominate our weather pattern for the first half
of the short term period with tranquil weather conditions along with
large scale upper level convergence keeping winds light and
variable. Latest 12z model and numerical guidance shows the center
of a large surface high moving northeast into Maine as we go through
the day on Thursday. With easterly winds around the departing high
pressure in conjunction with a weak surface warm front moving north
from the Great Lakes associated with a low pressure system over Lake
Michigan...a southeasterly to east-southeasterly flow will develop
across the region. T850 and t925 profiles show cold air funneling
down equatorward on the east side of the high pressure system.
This will funnel in cooler conditions for western New England with
t850 ranging between -2c and -5c and t925 ranging between -1c and
1c. This will cause temperatures to have some gradient developing
based off of terrain. High temperatures on Thursday will struggle
to get out of the 40s for the Adirondacks and especially in the
Berkshires and southern Green Mountains where down slopping winds
will cause local valley areas to reach the lower and middle 50s under
tranquil weather conditions. Temperatures Thursday night will be
well below normal with low temperatures ranging from the low to
upper 20s with light and variable winds

As we go into the day on Friday...latest probabilistic guidance
shows a progressing upper level trough with a weak surface front
that is very limited in moisture sources. This will limit quantitative precipitation forecast to
areas well north and west of the immediate capital region Friday
afternoon into Friday night where the highest confidence exists.
Some model guidance shows a southerly stream jet streak that will
phase into the northerly flow that might enhance upper level
dynamics for greater quantitative precipitation forecast amounts. At this time...due to initial
limited moisture sources and the jet streak being displaced further
east of the region when dynamics become favorable..chances of a high
quantitative precipitation forecast situation are limited but will be monitored. Diurnal temperature
trends in the evening hours will support rain/snow mix in the
highest terrain. Otherwise...lowest probability of precipitation will exist south and east
of the immediate capital region farthest removed from the upper
level trough location. High temperatures on Friday will range from
the upper 40s/lower 50s in high terrain to upper 50s in valley
locations with lows Friday night ranging from low to middle 30s.

&&

Long term /Saturday through Wednesday/...
the European model (ecmwf) is now trending warmer...and the long term period will
begin on the wet side...with showers for the start of the weekend...
but things will quickly dry out as a cold front slides southeast
across the forecast area...and high pressure moves in from James Bay
and Ontario. A relatively weak and moisture-starved frontal
boundary will move into the region Sunday night...rendering a chance
of showers for Monday. Chance probability of precipitation will linger through Tuesday...
though...given the high uncertainty of where this weak frontal
boundary actually ends up as it taps on increasing Gulf moisture.
Eventually...a large ridge of Arctic high pressure pours down
through the Great Lakes region...and Wednesday will likely finally
be dry again.

Despite it being an Arctic high moving in for Wednesday...this will
be a well modified air mass...and temperatures from about the upper
50s to around 70 degrees on Tuesday will be only a few degrees
cooler on Wednesday. Saturday will be the coolest day of the
period...with high temperatures from the middle 40s to middle 50s.
Sunday...like Wednesday...will see temperatures in the 50s and
60s...and Monday will be almost a Carbon copy of Tuesday/S warmth.
Low temperatures Saturday night will be in the middle 20s to upper 30s
range...and these will rebound about 5 to 10 degrees for Sunday
night...and another 5 degrees for Monday night. Tuesday night
should be slightly cooler under partial clearing.

&&

Aviation /02z Thursday through Monday/...
VFR conditions will prevail through the 24 hour taf period ending
00z Friday...as high pressure crests over the region tonight and
moves into New England on Thursday. Skies will remain clear except
for some occasional high level cirrus clouds.

Winds will be light and variable tonight...becoming east-southeast
around 10 knots by late Thursday morning.

Outlook...

Thursday night to friday: no operational impact. No sig weather.
Friday night: low operational impact. Slight chance of rain showers.
Saturday: moderate operational impact. Chance of rain showers.
Saturday night to sunday: no operational impact. No sig weather.
Sunday night: no operational impact. No sig weather.
Monday: moderate operational impact. Chance of rain showers.

&&

Fire weather...
old front that passed through the region earlier in the day
provided a half an inch to one and and a half inches of rainfall
across the region. This was followed by snowfall ranging from around
one inch to around four inches of snowfall.

With a strong April sunshine...most of the snow should be gone by
dark. The only exception would be wooded areas...and of course
portions of the Adirondacks where old snow covered still remain.

The wind will go calm tonight with temperatures well below freezing
region wide.

Dry weather with a slow moderating trend for Thursday and Friday.
Daytime winds will be lighter...generally from the southeast to
northeast 5 to 15 miles per hour.

The next chance of precipitation will be on Saturday. Some of this
might be mixed with snow in the mountains. At this point...the quantitative precipitation forecast
looks light...below a quarter of an inch in the valleys...but we
might exceed that amount across the southern greens of Vermont.

&&

Hydrology...
rainfall and snow melt have lead the western Mohawk Valley and
southern Adirondacks and upper Hudson River valley. Flood warnings
are in effect at many river points in these areas with mainly
minor or moderate flooding occurring. However there is major
flooding occurring along the Schroon river at riverbank. Larger
main Stem rivers have crested.

Dry weather will be in store through Friday...and rivers continue
to recede into the weekend. The next chance of precipitation
looks to be Saturday. Some precipitation could fall as wet snow
across the higher terrain. Quantitative precipitation forecast amounts look fairly light at this
time which will be updated with future forecasts.

&&

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

&&

$$
Synopsis...lfm/jpv
near term...hwjiv/lfm/jpv
short term...lfm
long term...elh
aviation...jpv
fire weather...hwjiv/lfm
hydrology...snd/hwjiv/lfm