Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 191036
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
636 AM EDT Thu Apr 19 2018

.SYNOPSIS...
A low pressure system passing to the south will bring
rain and snow showers to the region today, with mainly light
accumulation over the higher terrain. Another cool and mainly cloudy
day is expected Friday. Temperatures will moderate over the weekend
with dry weather and sunshine returning.

&&

.NEAR TERM /THROUGH TONIGHT/...
As of 630 am, solid area of precip associated with a brief shot
of midlevel frontogenesis is located roughly south and east of
the Catskills, Capital District, and southern Vermont. Latest
CAMs suggest this area should exit the area quicker than
initially thought, likely exiting most of the area by 12Z or so.
Relative lull in forcing in its wake and have cut down on PoPs
for the rest of the morning. P-type has been mainly snow above
500 feet and mainly rain below. Light accumulations have been
noted on some of the NYS Mesonet cams over the Catskills and
Taconics.

Previous discussion...

As of 330 am, area of precip on the doorstep of our forecast
area downstream of well- defined midlevel wave over IN. The
precip is being forced by dynamic lift downstream of the upper
wave as well as an area of midlevel frontogenesis. Latest
guidance is in pretty good agreement flashing this area of
forcing across our forecast area roughly through 12Z, with best
lift and thus highest precip likelihood across areas south of
I-90. Recent model guidance, particularly CAMs, have come down
in the QPF department with this activity, and the going forecast
reflects this downward trend. As for p-type, forecast soundings
and current obs suggest mainly snow as this activity works into
the area prior to sunrise, aside from perhaps brief rain before
wet bulbing occurs and perhaps across the southern tier of
counties where wetbulb temps are a touch higher. Light grassy
accumulations are possible nearly everywhere, but snow will
likely have a hard time sticking to pavement below 1000 feet
elevation. Above 1000 feet, particularly south of I-90, up to 2
inches or so is possible through midmorning.

As this area of forcing passes through after 12Z, there will
likely be a lull in precipitation. Have tried to work this idea
into the hourly PoP forecast. As a trailing wave now over
northern Lake Huron approaches, another round of precip is
likely after 18Z, especially from the Catskills, Capital
District, and southern Vermont south and east. As the boundary
layer warms, much of this second round will be in the form of
rain below 1500 feet elevation, with mainly snow above. Highs
today side toward the colder 2m temps of the NAM/ECMWF given
cloudy skies and precipitation. These highs are likely to be
15-20F below normal.

Tonight, the latter midlevel wave will carve out a trough
encompassing the northeast US with cyclonic flow at midlevels
and west-northwest flow at low levels. It appears to be a
relatively good setup for upslope snow showers over portions of
the western Adirondacks, Berkshires, and especially the
southern Greens above 1500 feet where around 2 to 4 more inches
of accumulation is possible (locally higher). Lake effect snow
showers will also drift across parts of the Mohawk Valley and
eastern Catskills in the northwest flow. Most other areas will
see no more than isolated to scattered snow showers overnight.

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY/...
The upper low will pull away during this time period, although
broad troughing will remain in place. Friday, cold cyclonic flow
continues with H850 temps still averaging around -8C. Upslope
snow showers will continue over the western Adirondacks and
southern Greens but diminish during the day. Mostly cloudy and
cool for the region again with highs still around 15F below
normal. A bit more sunshine will occur over areas south of I-90.
A good pressure gradient will ensure breezy conditions as well.

Friday night into Saturday, a bit more of a clearing trend takes
hold as weak height rises occur. Though temps will remain below
normal Saturday, they will average a good 5-10F warmer than
Friday, so it may not feel all that bad considering our recent
bout of chilliness.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Dry weather is expected during most of the long term forecast period
with the exception being on Wednesday when scattered rain showers
are expected.

For the period from Saturday night through Tuesday night dry weather
is expected as a large ridge of high pressure builds into the region
from the Great Lakes and settles overhead on Sunday before moving
into New England on Monday and off the eastern seaboard on Tuesday.
An area of low pressure along with a cold front will be approaching
the area later on Wednesday. Lows Saturday night will be in the 20s
to lower 30s with highs on Sunday in the upper 30s to mid 50s. Lows
Sunday night will be in the mid 20s to mid 30s with highs on Monday
in the upper 40s to lower 60s. Lows Monday night will be in the
upper 20s to mid 30s with highs on Tuesday in the upper 50s to mid
60s. Lows Tuesday night will be in the 30s with highs on Wednesday
in the upper 40s to mid 50s.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
Mainly VFR/MVFR conditions expected through much of the TAF
period ending at 12Z Friday. Moisture ahead of a warm front and
an area of low pressure will be across the region this morning.
Precipitation will generally be a mixture of snow and rain
dependent upon the thermal profile in the lower levels of the
atmosphere. Conditions will generally become VFR again this
evening as the low pressure system and frontal boundaries pass
off to our south and east. There will still be a chance of
precipitation so have included PROB30 for MVFR/IFR conditions
from late this afternoon up until 03Z-07Z.

Winds will be light and variable to calm becoming north to
northwest at 5 to 10 kts this morning except at KPSF where
winds this evening will be gusty with gusts up to 24 kts.

Outlook...
Friday: Low Operational Impact. Slight Chance of SHRA.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: No Operational Impact. NO SIG WX.
Sunday: No Operational Impact. NO SIG WX.
Sunday Night: No Operational Impact. NO SIG WX.
Monday: No Operational Impact. NO SIG WX.

&&

.FIRE WEATHER...
Another period of light to moderate rain and snow is expected
today. Cool and moist conditions will continue into Friday, so
fire weather concerns will remain minimal. A warming and drying
trend will occur over the weekend, although temperatures will
still remain below normal.

&&

.HYDROLOGY...
Rivers and streams are currently slowly receding from heavier
rainfall earlier this week.

Rain and/or snow is expected today, with total liquid
equivalent amounts of one to three tenths of an inch. This
precipitation will not be enough to cause any flooding concerns.
Although a few light rain or snow showers may linger into
Friday, dry weather is expected over the weekend.

Temperatures will generally be below normal through the rest of
the week with minimal sunshine, limiting snowmelt for the
higher elevations. Temperatures will moderate by the weekend.


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...Thompson
NEAR TERM...Thompson
SHORT TERM...Thompson
LONG TERM...11
AVIATION...11
FIRE WEATHER...Thompson
HYDROLOGY...Frugis/Thompson



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