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fxus61 kaly 222020 
afdaly

Area forecast discussion
National Weather Service Albany New York
420 PM EDT sun Sep 22 2019

Synopsis...
high pressure off the mid Atlantic coast will bring mild
conditions to the region tonight. A cold front and a strong upper
level disturbance will bring showers and isolated to scattered
thunderstorms tomorrow afternoon into the early evening. A cooler
air mass will be over the region on Tuesday with isolated to
scattered showers persisting during the day especially from the
Mohawk Valley north and east, as fair and dry weather returns for
the mid week.

&&

Near term /until 6 am Monday morning/...
as of 420 PM EDT...a warm finish to the astronomical Summer of
2019 for eastern New York and western New England with high pressure
near the mid Atlantic coast funneling northward a warm and humid
air mass. Sfc dewpts have risen into the upper 50s to lower
60s. Max temps have reached the mid and even upper 80s in parts
of the valleys. The record high for Albany today is 95 degrees
set back in 1895!

The majority of the high resolution mesoscale guidance has
trended drier for the mid to late PM across the west northwest
portion of the forecast area. We did keep an isolated threat for
a shower as a lake breeze or differential heating boundary may
focus a few over the southern Adirondacks, west-central Mohawk
Valley and the northern Catskills between 21z-00z. The 3-km NAM
and arw-wrf2 support this...but the 3-km hrrr and traditional
arw-WRF indicate dry conditions. Any activity should shrivel up
with the loss of the diurnal heating.

Tonight...a balmy night will be on tap compared to the last
several with high pressure off the mid Atlantic coast continuing
to pump mild air into the region. Lows will be in the mid and
upper 60s in the lower elevations with upper 50s to lower/mid
60s over the higher terrain. Some low stratus may form and creep
into western New England and the Mid Hudson valley. South to
southwest winds will be 5 to 15 mph.

&&

Short term /6 am Monday morning through Wednesday/...
tomorrow...the mid and upper level ridge breaks down as the flow
aloft strengthens from the southwest. A potent mid and upper
level low will be approaching from the Great Lakes region and
Ontario. A muggy air mass will continue ahead of the approaching
short-wave trough and a sfc cold front. Scattered showers will
likely Blossom in the afternoon ahead of the front, as mid and
upper level heights fall. Some isolated to scattered
thunderstorms are possible, but again instability in any shape,
variety or computed form looks fairly weak with 750 j/kg or
less with the sfc dewpts in the 60s. Their could be a few gusts
of wind in the 35-50 mph range with any taller updrafts
achieved. The deep shear and dynamics aloft are good with upper
level divergence and the forecast area near the left front
quadrant of a mid an upper level jet streak by 00z/Tue. The
severe threat is not zero, but the probability is very low. The
greatest chance for thunderstorms looks like 4 PM to 10 PM.
Highs will be above normal with 70s to lower to mid 80s across
the region. Precipitable waters will surge +1 to +3 stdevs above normal based
on the 12z gefs, but with flow so fast aloft, and Bone dry
conditions lately (no rain in a week), any bursts of rain will
be quick. A tenth to a third of an inch of rain will be
welcomed.

Mon night...cooler air will invade the region for the 1st day of
autumn (it will have begun at 350 am EDT on mon). Some isolated
to scattered showers will linger into the early evening with the
upper low moving overhead. Lows will fall back into the 50s to
around 60f across the region.

Tuesday...clearing is expected south of the I-90 corridor, but
the cyclonic vorticity advection with the closed upper low
coupled with minimal heating will allow for terrain forced and
instability showers forming over the northern zones. Any
additional quantitative precipitation forecast will be light. H850 temps will be a shade below
normal, but nothing way below normal for the opening days of
fall. It will be brisk and cool compared to the previous few
days with highs in the mid 60s to lower 70s in the valleys, and
50s to mid 60s over the higher terrain.

Tuesday night to Wednesday...high pressure builds in with fair
and dry weather returning. A cool night with temps in the 40s
to around 50f will be followed by a nice start to the mid week
with highs near normal in the 60s to lower 70s for most of the
region.

&&

Long term /Wednesday night through Sunday/...
the period starts out Wednesday night with a progressive cold front
and associated low-amplitude upper level trough approaching from the
Great Lakes region. Guidance in good agreement with timing, as a few
showers may make it into the the northwest part of our area by
sunrise Thursday. Much of the area will remain dry through the night.

The front and upper trough will move across our region on Thursday.
Once again moisture looks to be limited, although low level
convergence along the front and some forcing from the upper trough
should result in at least scattered showers for much of the area.
Temperatures will continue to be mild ahead of the cold front,
cooling off in the Adirondacks where the front will be likely moving
through earlier in the day.

A period of dry and increasingly warmer weather then looks to occur
during the Friday through Sunday time frame, as yet another upper
level ridge is expected to build along the East Coast. Initially,
temperatures will be slightly above normal Friday, but then well
above normal levels will be possible over the weekend as the ridge
strengthens. There are some model differences, with the GFS
indicating a cold front passage Saturday night. However, will side
more with the drier/warmer European model (ecmwf) and CMC, which have the strong
upper ridge remaining in place.

&&

Aviation /20z Sunday through Friday/...
VFR conditions are expected through much of the taf forecast
period as high pressure holds its influence on the region.
Higher clouds will continue to filter out the sun this afternoon
along with some diurnal cumulus clouds. The high and mid level
moisture will continue to increase into tonight ahead of a cold
front. Some light patchy fog may be possible at kgfl/kpsf close
to sunrise but with light winds in place, do not expect any
dense fog to form. Precipitation chances increase beyond
18z/Monday with the cold front.

Winds will remain light and variable through early this morning then
begin increasing from the southwest between 5 and 10 kts towards
18z. Low level wind shear appears to be a concern overnight as winds increase
aloft but remain light near the surface. After daybreak Monday,
winds will increase to around 10 kts with gusts up to 20kts by
18z.

Outlook...

Monday night: moderate operational impact. Chance of rain showers.
Tuesday: low operational impact. Slight chance of rain showers.
Tuesday night to friday: no operational impact. No sig weather.

&&

Fire weather...
high pressure off the mid Atlantic coast will bring mild
conditions to the region tonight. A cold front and a strong upper
level disturbance will bring showers and isolated to scattered
thunderstorms tomorrow afternoon into the early evening. Cooler
conditions return on Tuesday, as an upper low will keep isolated
to scattered shower going for locations north of the capital
region.

The relative humidity values will increase to 75 to 100 percent Monday morning,
and the drop to 45 to 75 percent by the afternoon. The maximum
relative humidity values Tuesday morning will be in the 85 to 100 percent
range.

The winds will be south to southwest at 5 to 10 mph tonight,
then increase to 10 to 20 mph during the afternoon before
veering to the west to northwest at 10 to 20 mph by the late
afternoon into the early evening.

A widespread wetting, but light rain may occur across the
region tomorrow into Tuesday with amounts range from a tenth to
third of an inch or so. It has not rained in about a week.

&&

Hydrology...
no hydrologic problems are anticipated across the region over
the next 7 days.

The next chance of rain will be ahead of a frontal boundary and
an upper level disturbance on Monday into Tuesday morning. Most
spots will see between one tenth and one third of an inch of
rain, which will have little impact on area rivers and
streams...maybe flows will rise a few centimeters and then
recede.

According to USGS streamflow, most area rivers are
seeing near normal or below normal flows for mid to late
September.

Lingering showers on Tuesday (especially for northern areas)may
yield additional rainfall amounts of a few hundredths to a
tenth of an inch.

More dry weather is expected for Tuesday night into the mid
week.

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...wasula
near term...wasula
short term...wasula

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