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fxus61 kaly 221651 
afdaly

Area forecast discussion
National Weather Service Albany New York
1251 PM EDT Tue Oct 22 2019

Synopsis...
some light rain is possible this afternoon with a soaking
rainfall tonight as a front moves across the region. The
rain is expected to tapering off late with fair weather
returning Wednesday as higher pressure builds in.

&&

Near term /until 6 PM this evening/...
updated at 1 PM. Minor changes to reflect latest trends
regarding a few light showers that have developed over eastern
New York ahead of the main line of showers still back in western New York.
Scattered showers will continue across the area in south-
southeasterly flow pattern with modest warm air and moisture
advection. The main period of rain will be tonight when a
moderately strong frontal system advances eastward across the
area, with a surface wave of low pressure developing along the
front and moving northeast across New England. Previous
discussion is below.

Updated at 10 am. Just minor changes to the near term forecast
with this update based on latest trends. With thick cloud cover
in place from the capital district south and westward we are
expecting only a slow rise in temperatures today with highs in
the mid to upper 50s. Scattered showers are still expected to
develop this afternoon with increasing moisture advecting
northward across the area, but the best chance for rain will
continue to be tonight as the front and associated surface wave
moves across the area. Previous discussion is below.

Ridging, at the surface and aloft, will continue to shift
eastward off the coast as clouds stream in ahead of an
approaching boundary. A mature stacked low pressure over the
upper mid west will drift northward across the western Great
Lakes today as its associated fronts race eastward occluding as
they approach during the day. With the increasing southeast
flow low level clouds will move in and some light rain and
drizzle will occur this afternoon. The steady rain is expected
to begin to move in west of the Hudson River valley by late in
the day.

The southeast flow will become quite breezy across the southern
Adirondacks and higher terrain of southern Vermont and the
Berkshires. Wind gusts of 25 to 30 mph are expected with the
winds at their strongest this afternoon.

Highs in 50s today with a few readings around 60 degrees across
the upper Hudson Valley and any 40s limited to above 2500 feet.

&&

Short term /6 PM this evening through Thursday night/...
soaking rainfall tonight with bulk of the rain occurring this
evening as an occluded boundary moves across the local area.
Guidance indicates development of a secondary low along the
boundary over the Delaware-Maryland-Virginia region by 00z/Wednesday as a
vigorous short wave rotates about the east side of the low.
Guidance keeps the system progressive. The rain is expected to
quickly taper off late at night as the boundary and weak low
move off our the east. Refer to hydrology section for forecast
rainfall amounts and impacts.

The flow aloft is expected to flatten across the region
Wednesday as short wave moves off northeast. While at the
surface, higher pressure builds in from the southwest as the
sprawling high across the south shifts eastward. Expecting
breezy conditions Wednesday with a return to fair weather to
all but the far northwest portion of the forecast area.
Southwesterly low level flow will lead to lake enhanced showers
off Lake Ontario into the early evening hours. With increasing
sunshine from south to north expecting seasonable temperatures.
Westerly winds are expected to gusts into the 20s across much
of the area. Winds will diminish Wednesday night and temperatures
are expected to drop into the 30s across the area.

Southwesterly flow develops aloft Thursday as additional short
wave energy rotates about the stacked low as it continues to
move gradually northeastward across Hudson Bay. It will be
milder with highs around around 5 degrees higher than Wednesday.
An increase in clouds is expected across the area Thursday into
Thursday night with fair conditions.

&&

Long term /Friday through Monday/...
we begin the long term period on Friday with a ridge of high
pressure positioned off the southeast U.S and a longwave trough
across southern Canada. As is typical with this type of
synoptic set- up in autumn, guidance shows a baroclinic zone
positioned southwest to northeast across eastern New York and western
New England. A shortwave within the base of the trough looks to
swing from the Great Lakes towards the northeast which should
provide sufficient forcing for ascent along the temperature
gradient to produce some showers. There is still notable
discrepancies among the latest members of the model suite but we
sided with the European model (ecmwf) solution as it seems the most reasonable.
The CMC-New Hampshire keep US mainly dry and the GFS looks much too wet.
Therefore, we placed chance pops for all areas during the day
Friday but kept most below 50% pops in case the wave along the
front develops further to our east. Showers generally seem to be
light as the better forcing may not arrive until the boundary
shifts to our east.

Temperatures Friday were a bit challenging since the baroclinic
zone should exit as a cold front with a cool Canadian air mass
sliding in as the boundary departs. Since both the CMC and European model (ecmwf)
keep the shortwave flatter, the warmer air on the east side of
the boundary may not have the needed forcing to push it
northward into our region. Thus, we sided with the cooler end of
guidance and show high temperatures staying in the 50s.

Our boundary exits as a cold front Friday night taking the
showers with it. The westerly flow in its wake should advect in
the cooler Canadian air mass characterized by 850mb isotherms
ranging -1c to - 4c into our area. Since the Delta-ts between
the sfc waters of Lake Ontario and the air mass moving overhead
look meet the critical 13c threshold, some lake enhanced
showers/clouds could linger into Saturday morning. Temperatures
overnight should cool into the 30s as cold air advection sets in
and showers in the higher terrain of the Adirondacks could mix
with some snow. No accumulations expected at this Time.

Lake effect clouds/showers may linger into Saturday morning but
sufficient subsidence should arrive as a large ridge of high
pressure advances eastward into the northeast. With the chillier
Canadian air mass overhead, high temperatures should stay in
the low to mid 50s. The ridge axis in place should lead to clear
skies and calm winds which should set the stage for radiational
cooling Sunday night. With dew points expected to fall into the
30s, we expect overnight lows to fall well into the 30s
throughout the region.

High pressure stays in control at least to start Sunday but the
ecwmf and CMC-New Hampshire both show a compact shortwave riding along the
top of the ridge into the northeast leading to our next chance
for precipitation. The GFS shows a much flatter 500mb pattern
compared to the more meridional look to the European model (ecmwf) and CMC so it
keeps US mainly dry. Once again we decided to side with the
European model (ecmwf)/CMC output and increase pops heading into Sunday night.
Despite the southwesterly return flow setting in, we show
temperatures on Sunday remaining below 60 due to increasing
clouds.

Uncertainties in the model guidance become more significant for
Monday and Tuesday. Therefore, we show seasonable temperatures
and slight chance pops due to potential for addition shortwaves
to cross through the region.

&&

Aviation /18z Tuesday through Sunday/...
thick cirrus deck has overspread the entire region and
southeasterly flow may lead to MVFR ceilings at pou, psf and alb
this morning, mainly after 13-14z. Given pou is already few018,
we decided to have pou go down to MVFR ceilings earliest. As
moist southeast flow increases off the Atlantic Ocean this
morning, a few light showers and potentially lower end MVFR
ceilings are possible 18z - 22z this afternoon. Did not have
high confidence on this potential so illustrate the hazard with
a tempo group.

By 00z-03z, widespread moderate rain will move into the region
and likely lead to MVFR visibilities and low end MVFR
ceilings. Steady rain should turn to showers after 06z with
ceilings potentially reducing to IFR levels at all taf sites
through 12z/23.

Southeasterly winds this morning should increase with sustained
winds ranging to 5-8kts with gusts at alb and psf gusting up to
20kts. Low-level wind shear is then possible this evening as
surface winds turn light but winds at 2kft remain strong at
30-40kt. After 06-08z, the winds should turn westerly as the
front exits the region.

Outlook...

Wednesday: low operational impact. Breezy.
Wednesday night: no operational impact. No sig weather.
Thursday: no operational impact. No sig weather.
Thursday night: no operational impact. No sig weather.
Friday: moderate operational impact. Chance of rain showers.
Friday night: moderate operational impact. Chance of rain showers.
Saturday: low operational impact. Slight chance of rain showers.

&&

Fire weather...
some light rain is possible this afternoon with a soaking
rainfall tonight. The rain is expected to tapering off late
with fair and breezy conditions Wednesday.

&&

Hydrology...
some light rain is possible this afternoon with a soaking
rainfall tonight tapering off late as a front moves across the
region. The system is progressive. Rivers will rise but are
forecast to remain below flood stage. Quantitative precipitation forecast is expected to range
from around 1/2 inch across portions of the Mid Hudson valley
and northwestern Connecticut up to 1 1/4 inches across the
southern Adirondacks and across the higher terrain of the
southeastern Catskills. Nuisance ponding of water is possible,
especially where leaves clog drains.

Fair weather Wednesday and Thursday with chances for showers
Friday and Friday night with light quantitative precipitation forecast expected. Fair weather is
expected to return for 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.
New York...none.
Massachusetts...none.
Vermont...none.

&&

$$
Synopsis...iaa
near term...iaa/mse

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