Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 252341
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
641 PM EST Sun Feb 25 2018

.SYNOPSIS...
High pressure will begin to build in tonight. The high is
expected to dominate our weather into the middle of the
week bringing sunshine and mild temperatures.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As of 641 PM EST...IR satellite imagery shows plenty of clouds
remain in place across the region, although clearing is upstream
over the eastern Great Lakes. Through the remainder of the
evening hours, sky cover will remain cloudy with temps ranging
from the low 30s to low 40s and only slowly falling.

Higher pressure will begin to build in at the surface tonight
in the wake of an occluded front. Until then conditions will be
favorable for fog with light winds, high low level moisture, wet
or snow cover ground, and decreasing cloud cover. Conditions
should begin to improve late tonight as winds shift to the west
and increase in speed mixing the low levels. Expecting lows in
the upper 20s to lower 30s.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/...
Heights aloft will begin to rise Monday with the passage of the
short wave with ridging remaining over the region into mid week.
The center of the surface high is forecast to pass to our south
and moving gradually off the mid Atlantic coast Tuesday and
Wednesday. This will result in fair and mild weather for the
area with sunshine. Expecting daytime highs around 10 degrees
above normal Monday and Tuesday and around 15 degrees above on
Wednesday. Monday night will be the coldest night with lows in
the upper teens and 20s with lows Tuesday night in the upper 20s
to lower 30s.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Although the weather will be quiet to begin the long term period, a
complex coastal storm looks increasingly likely to impact the region
for Thursday into Friday.

High pressure looks to depart offshore on Wednesday night.  Although
it should be dry for most areas on Wednesday night, temps won`t be
too cold, with lows in the upper 20s to mid 30s and a partly cloudy
sky.

Although the details are still far from certain, it appears that a
storm system lifting out of the Mississippi Valley will be moving
towards the Great Lakes and Ohio Valley for Thursday.  This storm
looks to be phasing with some southern stream energy and moisture as
well and will be closing off to our southwest.  As this closed low
aloft slides eastward, a new surface low looks to develop off the mid-
Atlantic states and slowly drift northeast for Friday.  This storm
will be very slow to depart, as a strong blocking high will be in
place over Greenland and the North Atlantic, making the pattern
aloft rather stagnant.

With both a strong surface low and closed low aloft passing to our
south, our region will be dominated by very strong easterly flow
with the low to mid levels. The 12z GEFS suggest 850 hpa u-wind
anomalies of 3-5 STD below normal.  The 250 hpa u-wind anomalies are
also 2-3 STD below normal, signaling a slow-moving storm system.

Usually, in this type of pattern, precip is highly variable across
the area, with high terrain areas seeing moderate to heavy
precipitation, especially easterly facing slopes.  Some valleys will
have a tendency to downslope, although this doesn`t always mean
significant precip cannot occur in valley areas as well.  P-type
will be very tricky, as the boundary layer won`t have a ton of cold
air in place initially, although strong lift and wet-bulbing
processes can still allow for wintry precip.  Based off the latest
model and ensemble guidance, it appears high terrain areas may start
as rain/snow mix going over to snow, while valley areas may begin as
rain and eventually change to a mix or snow by later in the storm,
although there may be times when heavy precip rates flips p-type
over to all snow for periods of times.  For now, will go a little
colder than the model blend guidance with temps in the 30s to low
40s, although temps could be colder if the storm tracks further
south.  As expected, the operational models and ensembles still show
a huge range regarding total precip amounts, but there is certainly
the potential for heavy precip across our area.

Precip should be tapering off by Saturday morning, although this is
still far from certain. Behind this storm, some ridging may try to
build in from the west, allowing for dry weather with temps a little
above normal for the weekend, although this will also ultimately
depend on what happens with the late week storm.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Abundant low-level moisture and light winds will keep plenty of
low ceilings around this evening. Flying conditions are
generally MVFR with cigs 1500-2500 ft, although periods of IFR
have been occurring and are possible over the next few hours.
Towards midnight, the clouds may start to break up, but with
only light winds in place, the abundant low-level moisture will
lead to the development of radiational fog, which should
continue for the remainder of the night for all sites, with
IFR conditions expected thanks to visibility around 1-2 SM.

Around sunrise, westerly winds will allow for more mixing and
some drier air to work into the area. This should allow for
improvement back to VFR conditions for all sites on Monday
morning, with nearly clear skies. During the day Monday, west
to northwest winds will be around 10 kts, with a few higher
gusts at KALB/KPSF.

Outlook...

Monday Night: No Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: Moderate Operational Impact. Chance of RA.
Thursday Night: High Operational Impact. Likely RA.
Friday: High Operational Impact. Likely RA.

&&

.HYDROLOGY...
Rivers experiencing some minor rises in response to the the
runoff from the rainfall. Have had no reports of any flooding.
Looking at fair weather into mid week with mild days for meting
ice and snow with nighttime lows to freezing or below to slow
and even stop melt.

A moderate to heavy precipitation event is possible Thursday
through Friday night at a storm system impacts the region.
There is still much uncertainty as to QPF amounts and even
precipitation types.

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.
NY...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...IAA
NEAR TERM...IAA/Frugis
SHORT TERM...IAA
LONG TERM...Frugis
AVIATION...Frugis
HYDROLOGY...IAA



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