Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kaly 220232 
afdaly

Area forecast discussion
National Weather Service Albany New York
932 PM EST sun Jan 21 2018

Synopsis...
above normal temperatures will continue until mid
week. A low pressure system will impact the region late tonight into
Tuesday night bringing some mixed precipitation to the area and a
moderate to locally heavy rainfall. A colder, seasonable airmass
will be ushered back into the region behind the storm.

&&

Near term /through Monday/...
Winter Weather Advisory is in effect from 1 PM Monday until
7 am Tuesday for Hamilton and northern Warren counties in New
York, and southern Vermont...

As of 930 PM EST, some light precipitation is beginning to move
into the area this evening with temperatures right around the
freezing mark. This trend will continue through the overnight
hours. That being said, the forecast remains on track. Sent
updates to ndfd and web servers.

As of 730 PM EST, clouds continue to increase across the area
ahead of a low pressure system moving into the Ohio Valley.
Temperatures are currently in the low to mid 30s across the
region. So have freshened up the hourly pops and temps based on
recent trends and sent updates to ndfd and web servers. Further
details regarding the near term forecast follow.

Prev disc...a stationary front remains anchored across northern
New York and northern New England. This frontal boundary will
work a little farther south tonight as a low pressure system
moves into the Midwest with a warm front moving into the Ohio
Valley. On Monday the warm front will lift northeast into our
region. What all of this means is that there will be increasing
chances for precipitation through Monday. Based on partial
thickness values there will be a potpourri of precipitation
types with northern areas seeing more in the way of a wintry mix
and southern areas seeing mostly rain. Precipitation looks
mainly light through Monday with total quantitative precipitation forecast of less than a
quarter of an inch liquid equivalent. Lows tonight will be in
the upper 20s to mid 30s with highs on Monday in the 30s to
around 40.

&&

Short term /Monday night through Tuesday night/...
broad isentropic lift will be ongoing Monday evening with a band
of mostly rain continues to lift north along and north of i90.
Low level jet magnitudes increase overnight with the v-component
suggesting values at or above +3 Standard deviations above
normal with pwats approaching those values as well. While a mid
level dry slot is expected, we will keep chance pops in the
forecast at this time (periods of either light showers or
drizzle) along with patchy fog. Temperatures will be a bit
tricky within the warm advection and precipitation as
expectations are nearly steady or slowly rising values
overnight. Portions from Glens Falls into the southern greens
may hold temperatures near the freezing mark as this will
continue to be monitored as low level ageostrophic flow remains
from the northeast.

The aforementioned pwats anomalies will advect ahead of the
cold front expected to cross the region during the mid-day hours
Tuesday. A period of rain, moderate to briefly heavy if
convective elements were to be fully realized with showalter
values near 0c from Albany and points southward, expected where
we will keep categorical pops. Valley temperatures may climb to
around 50f with 40s elsewhere, along with the qpf, may result in
additional challenges with respect to ice jams (see Hydro
section below). Frontal passage is expected during the afternoon
where precip coverage and intensity should diminish as yet
another dry slot approaches.

Cold advection and increasingly cyclonic flow with embedded
short wave should bring about additional rain and snow showers
through the night. As colder air advects further eastward
overnight, precipitation transitions to all snow showers along
with some contribution from Lake Ontario. The other concern will
be the increasing winds overnight and BUFKIT profiles momentum
transfers suggest 30-40kts we may be able to tap into toward
sunrise. Temperatures will dip back below freezing as h850
temperatures are expected to drop from +7c to -10 to -15c.

&&

Long term /Wednesday through Sunday/...
the long term period will start out with a return to below normal
temperatures as an upper level trough digs southward across the
eastern Continental U.S.. this trough pushes off to the east Thursday as
longwave ridging builds into the region for the weekend as
temperatures moderate above normal and the next potential storm
system brings widespread precipitation.

On Wednesday, persisting cyclonic flow and low-level cold air
advection with h850 temps around -12c should support lake effect
snow in favored locations of the Mohawk Valley and western
Adirondacks. Low inversion heights expected to keep accumulations
fairly light. Winds will be gusty as well Wednesday into Thursday
with the cold advection. Lake effect snow chances diminish as
surface high pressure builds into the region Wednesday night/
Thursday with temperatures still below normal. Dry weather continues
Friday and Friday night as upper level ridging translates across the
eastern Continental U.S. With temperatures near normal.

Return flow kicks back in by Saturday providing a boost to
temperatures, bringing them back above normal (into the 40s). The
next potential storm system is expected to develop across the
Central Plains/Mississippi Valley Saturday. As this system shifts
east, isentropic lift will increase across our area and allow for
precipitation to return to the region Saturday night and persist
through Sunday.

&&

Aviation /03z Monday through Friday/...
low-level moisture advection will increase ahead of a low
pressure system moving across the Great Plains tonight. This
should allow cloud bases to lower to MVFR and perhaps IFR levels
late in the taf period. The moisture advection may be
accompanied by patchy drizzle or freezing drizzle as a warm
front focuses the moisture, especially after 06z. Fzdz appears
relatively more likely at kgfl and kpsf where temps are expected
to be lower, but cannot be ruled out at kalb/kpou where temps
may be around the freezing mark. Vsby restriction may exist in a
combination of dz and br.

Steadier rainfall will move into the area tomorrow afternoon
which may reduce visibilities and ceilings to IFR/LIFR through
the end of the period.

Winds will be light and variable throughout the taf period.

Outlook...

Monday: moderate operational impact. Chance of rain...dz.
Monday night: high operational impact. Definite rain.
Tuesday: high operational impact. Definite rain.
Tuesday night: moderate operational impact. Chance of rain showers...shsn.
Wednesday: no operational impact. No sig weather.
Wednesday night: no operational impact. No sig weather.
Thursday: no operational impact. No sig weather.

&&

Hydrology...
ongoing flooding due to ice jams will continue to be addressed
with areal flood warnings, as some lingering issues continue due
to existing ice jams which froze in place.

Temperatures will continue to run above normal into early this
week. Tuesday will be the mildest with highs mainly in the 40s
with a colder seasonable airmass returning Tuesday night and
through the remainder of the week.

A storm will bring a moderate to locally heavy rainfall to the
area. The rain is expected to be light during the day and in the
evening Monday with the bulk of the rain occurring Tuesday
morning into early afternoon. Quantitative precipitation forecast amounts are forecast at this
time to range from about an inch up to possibly 1 1/2 inches.
The higher amounts across expected east of the Hudson River
valley and across portions of the central/southeastern
Catskills.

The rain is expected to cause rises on rivers and streams, which
may move and dislodge ice and may cause flooding near ice jams.

Our latest winter/Spring flood potential outlook (esfaly) was
issued this past Friday evening.

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...Winter Weather Advisory from 1 PM Monday to 7 am EST Tuesday
for nyz033-042.
Massachusetts...none.
Vermont...Winter Weather Advisory from 1 PM Monday to 7 am EST Tuesday
for vtz013>015.

&&

$$
Synopsis...11
near term...11/jvm

National Weather Service Glossary of Abbreviations