Area Forecast Discussion
Issued by NWS Albany, NY

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957
FXUS61 KALY 220608
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
208 AM EDT Fri Mar 22 2019

.SYNOPSIS...
Low pressure, over Delaware this evening, will strengthen and
slowly move northeast to near Boston by Friday Afternoon.
Impacts from this noreaster will be rain, snow and gusty winds.
Although valley areas should see only 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 THIS MORNING/...
Upgrade to Winter Storm Warning for the Helderbergs and eastern
Catskills. Also Winter Weather Advisory expanded to include the
central/eastern Mohawk Valley, Capital District and Lake George
Saratoga Region.

As of 1245 AM EDT...Main change for this update was to increase
snowfall totals for the areas mentioned above where headlines
were expanded/upgraded. We are concerned about a large band of
heavy precip developing early this morning resulting in dynamic
cooling due to precipitation intensity. This will allow rain to
change to snow, even in valley locations from the Mohawk Valley
and Capital District northward. 00Z guidance including the HRRR,
NAMNest, and HREF all indicating increasing potential for a 2-4
hour period of moderate/heavy wet snow this morning. Noting the
850-700mb F-Gen max is now forecast to be just south and east
of the region, which would place a pivoting mesoscale band
(based on CSTAR research) across southern VT through the Capital
District, eastern Mohawk Valley and Helderbergs/Catskills.
Thus, the confidence for increasing snowfall totals and
expansion/upgrade of winter headlines which includes this
morning`s commute.

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 THIS 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 /06Z FRIDAY THROUGH TUESDAY/...
Coastal low pressure will approach from south central NJ early
this morning. It will move northeast to the Gulf of Maine by the
early afternoon and continue to slowly lift north to northeast
to New Brunswick by tonight.

Rain will quickly overspread the TAF sites early this morning.
The column will continue to cool down with the heavy pcpn, and
the low level cold air being drawn into the system for a
transition to snow and rain between 07Z-09Z/FRI at
KGFL/KALB/KPSF, then all snow shortly thereafter between 09Z-12Z
with MVFR cigs and vsbys quickly lowering to IFR levels in the
snow. The snow may become moderate to heavy in intensity with
LIFR conditions, especially with vsbys but for now we have kept
3/4SM with -SN. Further south, KPOU will hold as rain with IFR
conditions for most of the morning until at 15Z, when rain may
mix with the snow. The snow will last most of the morning, until
a transition back to -RA may occur at KGFL/KALB with the pcpn
becoming lighter in intensity. Low MVFR cigs and vsbys will
continue. KPSF will hold as all snow most of the day with
IFR/low MVFR conditions. We did briefly allow for a mix with
rain and snow around 21Z/FRI.

Expect widespread MVFR conditions in the late afternoon, but
the upper level low, and the intensifying storm near the Gulf of
Maine will funnel cold air back into the TAF sites early this
evening with rain transitioning back to snow at KALB/KGFL
between 23Z/FRI and 02Z/SAT. Vsbys may lower to IFR levels, and
cigs may remain low MVFR. KPSF will go back to snow with
IFR/LIFR conditions as the upslope snow potential increases.
KPOU will remain rain with MVFR conditions in the early evening
before colder air funnels in towards midnight.

LLWS was kept in at KPOU/KPSF from 07Z/FRI - 15Z/FRI as the east
to north 2 kft AGL winds increase to 35-40 kts with the sfc
winds remaining 10 kts or less.

The winds will be from the north to east at 5-12 knots this
morning, but will increase from the north to northwest at 10-15
kts by the late morning into the afternoon with some gusts 15-20
kts. The winds will further increase from the west to northwest
at 12-18 kts tonight with some gusts in the 25-30 kt range at
KALB/KPSF due to the strengthening low-level pressure gradient
and the strong cold advection.

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.

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...Winter Weather Advisory until noon EDT Saturday for CTZ001.
NY...Winter Weather Advisory until noon EDT Saturday for NYZ039>041-
     043-048>050-052-053-061-083-084.
     Winter Storm Warning until noon EDT Saturday for NYZ032-033-
     038-042-047-051-054-058-063-082.
MA...Winter Weather Advisory until noon EDT Saturday for MAZ025.
     Winter Storm Warning until noon EDT Saturday for MAZ001.
VT...Winter Storm Warning until noon EDT Saturday for VTZ013-014.

&&

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



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