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fxus61 kaly 221804 
afdaly

Area forecast discussion
National Weather Service Albany New York
204 PM EDT sun Jul 22 2018

Synopsis...
increasing humidity levels this afternoon with chances
for showers along with the threat for some isolated thunderstorms.
There will be greater chances for showers as well as thunderstorms
late tonight and Monday. Thunderstorms will be capable to produce
locally heavy rainfall. The weather remain humid and unsettled
through the mid week.

&&

Near term /until 6 PM this evening/...
as of 135 PM EDT...abundant cloud Clover over the region with
the occluded front lifting slowly north and east of the capital
region/Mohawk Valley. Some spotty or isolated light showers are
on the kenx and regional mosaic radar. We kept low chance or
slight chc probability of precipitation in for the duration of the afternoon. The
instability looks weak so only a slight chc of thunder. Latest
3-km hrrr/namnest support isold/widely sct/sct coverage at best
into early this evening. East/southeast low level jet continues to push
further north of the area, but some breaks in the clouds and the
latest vwp shows east/southeast winds mixing to sfc with a few
gusts are 30 kts at kalb/kddh. Breezy conditions will prevail
with increasing humidity levels.

Precipitable water values increased from 0.68 inches from the
00z aly sounding to 1.92 inches on the 12z sounding this
morning. With some breaks in the clouds expecting highs in the
70s above 1000 feet and in the lower 80s below 1000 feet.

&&

Short term /6 PM this evening through Tuesday/...
previous excellent forecast discussion with minor enhancements
as forecast pattern has not changed too much with the 00z
package:

Sunday night into Monday, the forecast area gets entrenched in
a warm and humid air mass with precipitable waters increasing to ~2.0" by
Monday afternoon. A deep fetch of tropical moisture will occur
between the offshore ridge that is slowly retrograding, and the
cut-off dipping southward into the Ohio and Tennessee valleys. It remains
challenging to pick out the individual impulses in the
channeled southerly flow, but a weak disturbance in the
European model (ecmwf)/GFS/NAM tries to move across the region Monday. Scattered
showers and thunderstorms may impact the region with decent
coverage on Monday where we will keep the likely pops. The
coverage looks maximized from the Hudson River valley westward
with the ridge building in. We will have to monitor for any
training individual or lines of showers or thunderstorms. Right
now, with dry antecedent conditions widespread areal flooding is
not expected at this time. Additional rainfall amounts of a
half an inch to an inch plus are possible in some locations
especially the eastern Catskills. Warm and more humid conditions
with lows will be in the mid 60s to lower 70s, and highs will
be mainly in the mid 70s to mid 80s in the sticky air mass with
high dewpts around 70f.

Monday night into Tuesday...the showers and thunderstorms should
die off with the loss of the diurnal heating, and the nearly
h500 600 decameter closed anticyclone north of Bermuda begins
to ridge westward further. This high amplitude ridge in the mid
and upper levels of the atmosphere will likely keep the cold
front well west of upstate New York and New England, and the coverage
of showers and thunderstorms will likely be isolated, but to
stay in collaboration with the neighboring wfos, we maintained
slight to low chance pops. Pulse type thunderstorms may pop up
west of the Hudson River valley due to differential heating
boundaries between the mtns and valleys. Precipitable waters remain elevated
near 2 inches which will allow for localized downpours. Lows
will be similar to Sun night, and highs will be in the upper 70s
to lower 80s over the mtns, and mid to upper 80s in the
valleys.

&&

Long term /Tuesday night through Saturday/...
strong upper level ridge located east of the region over the western
Atlantic will finally start to slowly drifting eastward for Tuesday
night into Wednesday. Meanwhile, what was once a closed off upper
level low over the deep south will be lifting northeast across the
Appalachians as a weaker and open shortwave trough, while much
stronger upper level energy dives from central Canada into the upper
Midwest.

The upper level ridge shifting away will allow for showers and
thunderstorms to start to become a little more widespread across our
area, especially by Wednesday afternoon, as daytime heating will
help develop convection across the area. With pwats rather high
(00z GFS suggesting around 2.00 inches for much of the area), any
shower or T-storm will be capable of heavy downpours. The strong
south-southwest flow at low to mid levels may also be conducive for
training storms, so will need to watch for that as well.

The strong upper level low over the upper Midwest will shift towards
the Great Lakes for Wednesday night into Thursday. With a moist
southerly flow still in place, widespread showers and thunderstorms
look to continue for both Wednesday night into Thursday, thanks to
the passing upper level shortwave and a nearby surface boundary.
Will need to continue to watch for locally heavy downpours as well,
as the high rainfall rates may allow for flooding of urban, poor
drainage, and low lying areas as well as smaller streams and creeks.

The passing of the surface front will help lower the coverage of
showers and storms for the remainder of the period (friday into
saturday), as some drier air starts to work into the region and the
best moisture plume shifts east of the area. Still, can't totally
rule out a shower around for Friday into Saturday, as the large
upper level low lifting from the Great Lakes towards southern Canada
allows for a continuous cyclonic flow with broad trough in place.

Through the entire extended period, temps look near to slightly
above normal, with highs reaching the low to mid 80s. Temps may be
slightly lower when convection is most widespread (such as
Wed/thurs). Overnight lows will generally be in the 60s and it will
remain muggy and sticky with dewpoints in the 60s. Even behind the
front for late in the week, dewpoints will still be in the upper 50s
to low 60s. Skies will generally be partly to mostly cloudy.

&&

Aviation /18z Sunday through Friday/...

MVFR ceilings in place at all tafs at the 18z update due to
high atmospheric moisture. While there are breaks of sun coming
up from the south, metars in southern New York/northern New Jersey are still
supporting MVFR conditons. Therefore, only introduced a tempo
group for VFR conditions at times this afternoon for alb and
pou to account for limited periods that ceilings rise to 35kft.
Gfl and especially psf likely remain MVFR through sunset. A few
isolated showers have develop in vicinity of our taf sits
thanks to differential heating and high humidity but coverage is
too isolated to introduce anything more than vcsh. The Breaks
of sun have also allowed southeasterly winds to increase and we
expect sustained winds up to 10-15kts with gusts 20-30kts until
sunset.

Once we lose daylight and boundary layer mixing subsides, expect
winds to decrease and reflected that trend in the latest
update. This should also allow ceilings to lower by 07-09z to
near 1500ft with psf potentially even lowering to IFR. Did not
have enough confidence to reduce psf to IFR conditions but tried
to allude to it by including sct007. High humidity remains in
place so cannot rule out a few isolated showers overnight so
continued the vcsh.

Expecting MVFR ceilings to linger through 18z Monday but showed
ceilings rising to near 2500ft by 15z to show some improvement.
Less confident that psf improve as much so continued mainly
1500ft ceilings there. Southeasterly wind should increase as
well by this time but should not be as breezy as today due to
cloud coverage so excluding any gusts mention.



Outlook...

Monday night: moderate operational impact. Chance of rain showers...tsra.
Tuesday: moderate operational impact. Breezy chance of rain showers...tsra.
Tuesday night: low operational impact. Slight chance of rain showers...tsra.
Wednesday: high operational impact. Likely rain showers...tsra.
Wednesday night: high operational impact. Definite rain showers...tsra.
Thursday: high operational impact. Definite rain showers...tsra.
Thursday night: moderate operational impact. Chance of rain showers...tsra.
Friday: moderate operational impact. Chance of rain showers...tsra.

&&

Fire weather...
fire weather concerns will be greatly diminished with periods of
showers and thunderstorms with higher moisture content through
most of this upcoming week.

The relative humidity values will increase to 75 to 100 percent Sunday morning
in the rain, and only lower to 60 to 80 percent during the
afternoon. The relative humidity values will be close to 100 percent by Monday
morning.

The winds will be from northeast to southeast at 10 to 18 mph
this morning with some gusts 30 to 40 mph possible over the
higher terrain especially south and east of the capital region.
The winds will be southeast to south at 10 to 20 mph on Sunday
afternoon, and mainly southerly tonight at 5 to 15 mph.

Additional locally heavy rainfall is possible on Monday into
the mid week.

&&

Hydrology...
unsettled weather impacts the Hydro service area /hsa/ through
most of the week.

These rain this morning had minimal impact on area river and
streams, as levels are quite low and our recent dry conditions
as noted in the latest drought monitor of d0-d1 levels.

A slow moving frontal system approaching from the west, along
with several weak disturbances moving northward within a very
moist airmass in place, could lead to scattered showers and
isolated to thunderstorms, some with locally heavy downpours
for late this afternoon through at least the middle of next
week. The front may stay far enough west due to high pressure
building in from the western Atlantic Ocean for better coverage
of showers and thunderstorms being west of the Hudson River
valley.

A potential will exist for training showers/thunderstorms that
would result poor drainage flooding or an isolated flash flood
if heavy rainfall repeatedly occurs over the same areas of the
hsa Monday to Wednesday, but confidence remains very low for a
Flash Flood Watch at this time.

The cold front may move through Thursday with scattered showers
and thunderstorms with more localized heavy rainfall. The
coverage of showers and thunderstorms will likely increase with
one to two inches of rainfall possible in some locations. A
drier air mass will likely build in toward 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/bgm/wasula
near term...iaa/bgm/wasula
short term...bgm/wasula

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