Albany, NY WFO Forecast Discussion

000
FXUS61 KALY 212358
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
758 PM EDT Thu Mar 21 2019

.SYNOPSIS...
Low pressure, just southeast of Washington DC this evening,
will strengthen and slowly move northeast to just east of New
Jersey by daybreak. Impacts from this noreaster will be rain,
snow and gusty winds. Although valley areas will only see a
light accumulation of snow, some significant snow totals are
possible across the hills and mountains. Behind the storm, it
will remain cold and blustery for Saturday, before milder
temperatures return for Sunday.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 756 PM EDT...Update mainly for temperatures which have
cooled considerably this evening with many places now in the
30s. A few lower 40s Hudson Valley and far southern part of
forecast area. Most obs sites above 1500ft msl are now 33F or
below and just before dark some web cams in the higher terrain
showed snow falling.

Trend in 18Z NAM and latest HRRR runs showing snow accumulating
even in most valley locations around daybreak tomorrow, with
very heavy NNE to SSW snow band west of Hudson River. Hopefully
00Z balloon soundings will help with temperature profiles for
later tonight as precip type looks tricky.

Previous...
Low pressure is located over eastern Virginia and this storm
will be deepening this evening into tonight as it lifts
northeast along the mid Atlantic coast. This low pressure is
quickly strengthening as the result of two separate pieces of
upper level energy that have phased over the mid-Atlantic and
will be even further strengthening by yet another northern
stream shortwave moving into the region on Friday.

A strong S-SE low-level jet (850 hpa v wind anomalies are about
2-3 STD above normal) is allowing for a period isentropic lift
for late this afternoon into early evening. An area of steady
light precipitation is lifting northward from the Catskills
across the Mohawk Valley and Capital Region. Most of this precip
is rain, although some wet snow is mixing in with the rain for
areas above 2000 ft in elevation (as seen in NYS Mesonet cams).
Hi-res model guidance (such as the 3km HRRR and NAM) show this
band lifting northwest this evening and rotating into central
New York for tonight. This should allow for a brief break in the
steady precip from the Capital Region on south and east for
later this evening.

However, steady precipitation will return to the whole region
from south to north for late tonight (midnight onward), as the
low pressure continues to lift northward and strong
frontogenesis sets up south of the area. Model soundings suggest
most of the area should be starting off as rain, as the entire
profile looks to be above freezing under 825 hpa. However, by
late tonight, temps aloft should be cooling, as both dynamical
cooling processes and the approaching cold pool aloft will allow
temps to drop off aloft. This should change precip over from
rain to snow across the higher terrain towards daybreak Friday.

Temps will be starting out this evening in the mid 30s to mid
40s and will be lowering into the low to upper 30s by late
tonight.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
Complex storm will be ongoing on Friday as low pressure
continues to strengthen as it lifts northeast along the coast.
The low pressure will be moving from NJ early in the morning
towards eastern Massachusetts by afternoon and reaching eastern
Maine by evening.

Although the main surface low will be moving away from the area
through the day, there still looks to be fairly steady
precipitation through much of the day, as the upper level
shortwave moving in from the Great Lakes will be phasing with
upper level shortwave lifting up the eastern seaboard. This
should provide plenty of lift and the cyclonic flow will keep
enough moisture in place as well.

With temps aloft continuing to cool, precipitation type will be
tied to elevation and precip intensity. High terrain areas
(mainly above 1000 feet) look to see mainly snow on Friday,
while valley areas will see primarily rain. It`s possible that
some brief burst of snow are possible even in valley areas
through the day within heavier burst of precipitation, so p-type
may be changeable at times. Temps will generally be in the 30s,
although the immediate Hudson Valley may reach into the 40s
during periods of light or no precipitation.

By Friday night into Saturday morning, temps (both aloft and at
the surface) will be continuing to cool off and p-type should
be changing to just snow across the entire region. However,
coverage of snow will start to be limited to upslope and lake
enhanced areas across the high terrain (especially after
midnight Friday night). Snow may especially linger across the
northern Taconics, southern Greens and northern Berkshires into
early Saturday, as these areas generally see persistent
snowfall with the upslope flow on the backside of the departing
storm system. Any lingering snow looks to end by midday on
Saturday. By this time, about 5 to 10 inches are possible across
the high terrain will locally 10-14 inches for the Rensselaer
Plateau and across the southern Greens. While most valley areas
(under 5000 ft) should only see 1 to 3 inches, some of the
outlying hillier areas (about 500-1000 feet in elevation) could
see 2 to 6 inches of snowfall.

Temps fall into the teens and 20s across the region for Friday
night. Temps during the day on Saturday should only reach the
mid 20s to low 40s for the region.

With the cooling temps aloft, good mixing is expected up to
about 850 hpa and some gusty winds will be picking up.
Based on model soundings, northwest winds may gust 30 to 45 mph
(and possible even a few higher gusts as well) for Friday night
into Saturday.

Although there will be plenty of clouds to start on Saturday,
there should finally be some breaks by midday and into the
afternoon. Even further clearing looks to occur Saturday night,
as high pressure starts to approach from the west, with temps
falling into the teens and 20s.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
A rather strong arctic front moves through Sunday night into early
Monday, then it appears an extended period of dry weather with a
moderation in the temperatures.

12Z Global Models are in rather good agreement with the overall
synoptic set up heading into the long term forecast period as
progressive trough will slowly be replaced by rising heights along
the eastern seaboard.  First, a dry start to Sunday as narrow ridge
slowly moves off the mid-Atlantic coastline as we will endure yet
another arctic frontal boundary that is set to move across the
region Sunday night.  Now, trends in the model RH and QPF fields
continue to diminish as this arctic boundary appears to not only be
limited in moisture, but also faster timing which limits moisture
entrainment from developing Central Plains storm system.  So with
this forecast update we will reduce PoPs a bit with a chance of
light rain/snow.  By Monday afternoon, the arctic boundary is
forecast to be well south of the region as dry air advection is
underway with a brisk northwest wind.

Tuesday through Wednesday, high confidence with large area of high
pressure of 1030-1035mb moves across the region.  This will keep the
weather tranquil with partly cloudy to mostly clear skies and light
winds.  Late March sun angle and slowly rising heights and thermal
column moderation should allow for seasonable temperatures to be
felt by the mid-week period.  The next potential for wet conditions
may not be until next weekend.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Showers have become less numerous with southeasterly winds
allowing ceilings to improve with VFR cigs except at KGFL which
is currently MVFR. Some improvement possible at KGFL before
next round of steady precipitation moves in bringing MVFR/IFR
conditions to the TAF sites.

Rain may mix with snow for a period at ALB and PSF 22/09Z -
22/15Z which could lower visibilities down towards 1-2SM with
GFL potentially becoming all wet snow for a period. Ceilings
should improve some by late morning trended back towards MVFR.
However, a round of snow accompanied by gusty northwest winds
could begin near the end of this TAF period around 22/23Z.

The winds will generally be from the northeast overnight ranging
from 5-15 kts. The winds will become northwest towards after
22/16Z.

Low-level wind shear may increase below 2 kft AGL at KGFL, KPOU
and KPSF after 06Z/FRI.

Outlook...

Friday Night: High Operational Impact. Windy. Likely RA...SN.
Saturday: Moderate Operational Impact. Windy. Slight Chance of
SHSN.
Saturday Night: Low Operational Impact. Breezy. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: Moderate Operational Impact. Chance of RA...SN.
Monday Night: No Operational Impact. NO SIG WX.
Tuesday: No Operational Impact. NO SIG WX.

&&

.FIRE WEATHER...
A coastal storm will bring rain and snow to the region for
tonight through early Saturday. High terrain areas will see a
moderate to heavy snow accumulation, which will add to the
snowpack already in place. This will help limit fire weather
concerns for the time being across the region.

&&

.HYDROLOGY...
No hydrologic issues are anticipated through early next week.

A slow moving coastal storm will bring rain and snow to the
region for tonight through early Saturday. About 0.75 to 1.25
inches of liquid equivalent is expected with this storm, with
much of this being in the form of snow across the higher
elevations.

The combination of high terrain snowfall and chilly temperatures
will allow for only limited immediate runoff with this storm
system. While some small rises are possible on rivers and
streams, no flooding is anticipated at this time. Dry weather is
then expected behind the storm for later Saturday into Sunday.
Just some scattered light rain or snow showers are expected on
Monday with the next frontal system.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory from 2 AM Friday to noon EDT Saturday
     for CTZ001.
NY...Winter Weather Advisory from 2 AM Friday to noon EDT Saturday
     for NYZ048-051-058-061-063.
     Winter Storm Warning from 2 AM Friday to noon EDT Saturday for
     NYZ032-033-038-042-047-054-082.
MA...Winter Weather Advisory from 2 AM Friday to noon EDT Saturday
     for MAZ025.
     Winter Storm Warning from 2 AM Friday to noon EDT Saturday for
     MAZ001.
VT...Winter Storm Warning from 2 AM Friday to noon EDT Saturday for
     VTZ013-014.

&&

$$
SYNOPSIS...SND/Frugis
NEAR TERM...SND/Frugis
SHORT TERM...Frugis
LONG TERM...BGM
AVIATION...SND
FIRE WEATHER...Frugis
HYDROLOGY...Frugis

NWS ALY Office Area Forecast Discussion