Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 201738
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
138 PM EDT Sun Aug 20 2017

.SYNOPSIS...
High pressure building into the mid Atlantic region will bring fair
weather and seasonable temperatures today. A southwesterly return
flow around the high will bring mostly sunny and hot weather
Monday into Tuesday. There is a threat for strong thunderstorms
later Tuesday and Tuesday night ahead of a cold front.

&&

.NEAR TERM /UNTIL 8 PM THIS EVENING/...
As of 1:29 PM...mostly sunny and fair weather continues across
the Albany Forecast Area. Temperatures range from around 70 in
the higher terrain to around 80 in the Mid Hudson Valley. Winds
are generally from the northwest at 10 to 15 MPH. Dewpoints have
dropped into the 50s all locations. This, coupled with the
breeze, is making for a pleasant late summer day. Little change
expected through the remainder of the day. Clouds and breeze
will diminish towards sunset with loss of sun`s heating.

Previous... A look out the window this morning shows evidence
of smoke aloft. A check of the visible satellite also indicates
some evidence for smoke as well. The non-operational GOES-16
aerosol product identifies smoke over Lake Ontario. The impact
of all of this - perhaps a degree or two less on the high
temperature today.

Some afternoon fair weather clouds should form but there should
be plenty of sun and a west wind will be breezy at times. Some
weak cold advection will be occurring but the sun and west winds
should help temperatures reach highs in the mid 70s to lower
80s. Will not make any changes to max temps for smoke.

&&

.SHORT TERM /8 PM THIS EVENING THROUGH TUESDAY NIGHT/...
Warm advection begins late tonight and through Monday. West
southwest boundary layer flow and warming boundary layer
temperatures will support lots of sun and mixing. The eclipse
will be seen quite well. We will see if limiting the sun during
the peak time of heating will keep high temperatures in the mid
to upper 80s or if there will be little effect on temperatures
and some areas approach 90. Highs around 80 to lower 80s higher
terrain.

Good run to run consistency in guidance the last couple of days
showing strong upper energy dropping out of Canada Tuesday to
just north of the Great Lakes by Wednesday. An upper impulse
tracking around the southern periphery of the primary upper
system will track through our region later Tuesday night and
Wednesday.

The initial approach of the upper energy combined with the
increased low level moisture and daytime heating will support a
pre frontal trough that will track east through our region
Tuesday afternoon and night. There are some discrepancies in
guidance as to how much instability will be over the region,
ranging from near 1000 J/kg to potentially over 2000 J/kg in
some southern areas Tuesday afternoon. There will be a strong
low level jet of 40+ Kt and approaching strong upper jet core.
However, midlevel lapse rates will not be very steep and it
will be quite warm aloft. Most of the instability will be
surface based, so daytime heating and dewpoints will be
important in evaluating whether our region sees the greater
instability or less instability.

Strong boundary layer winds and decent deep layer shear will
make up for any limitations in instability if there are any.
There should be enough instability, shear and upper dynamics for
the potential for severe thunderstorms Tuesday afternoon and
evening. Highs Tuesday in the upper 80s but maybe near 90
southern areas and lower to mid 80s northern areas.

Organized convection exits through the evening but the main
upper trough axis remains well west of our region and the
boundary layer thermal gradient leading edge of cooler and dryer
air does not track through our region until very late Tuesday
night or early Wednesday. So, there could be some scattered
showers and thunderstorms as the leading edge of the cooler air
approaches late Tuesday night. Since the low level temperatures
and dew points are not expected to fall too much behind the pre
frontal trough, lows Tuesday night will not be too cool, in the
mid to upper 60s but around 60 to lower 60s northern areas.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The extended portion of the forecast will feature cool and mainly
dry late August weather as we head into next weekend.

A strong cold front will be progressing across portions of southern
NY and New England Wednesday morning.  The latest GFS/ECMWF/Canadian
GGEM and several Global Ensemble members all show some residual
showers ahead of the front over portions of the mid Hudson Valley
and western New England in the morning.  A secondary cold front
associated with the upper trough may also focus some scattered
showers over the rest of the forecast area.  We kept a slight chance
of thunderstorms in over southeast portion of the forecast area
including the mid Hudson Valley/southern Taconics/NW CT with small
amounts of instability and dewpoints still in the lower to possibly
mid 60s.  Low and mid level cold advection will be going on during
the day, and H850 temps may start the day at +11C to to +16C from
northwest to southeast across the region,  but will lower to +9C to
+13C by the afternoon based on the 00Z GFS. It will become breezy
and less humid by the late afternoon. Highs will be mainly in the
upper 70s to lower 80s in the valleys with upper 60s to mid 70s over
the hills and mtns.

Wednesday night into Thursday...The cooler air mass continues to
build in with a mean longwave trough setting up over southeast
Canada, the Great Lakes Region, and the Northeast.  The 00Z GEFS
indicates H500 heights on the order of 1 to 2 standard deviations
below normal with H850 temps slightly below normal, especially west
of the Hudson River Valley.  Some short-wave energy moving through
the cyclonic flow in the upper trough will focus some lake effect
isolated to scattered rain showers downwind of Lake Ontario that may
impact the western Adirondacks, and west central Mohawk Valley.
Diurnal cumulus will likely pop-up along or near the higher terrain
too. Otherwise, humidity levels will be comfortable with partly to
mostly sunny conditions during the afternoon with a large Canadian
anticyclone ridging in from Upper Midwest and Western Great Lakes
Region.  Lows Wed night will be mainly in the 50s with some upper
40s over the southern Adirondacks, eastern Catskills and southern
Greens,

Thu night into Sat...The air mass will feel a bit like early autumn
with temps ranging from the mid 40s to mid 50s both Thu and Fri
nights. There could be some patchy radiational mist or fog along or
near the major river valleys.  H850 temps will only be in the +8C to
+10C range over the region on Friday with limited mixing due to the
strong subsidence from the sfc high with max temps in the 60s over
the mountains and mainly lower to mid 70s over the hills and in the
valleys with a few upper 70s in the mid-Hudson Valley and NW CT. Not
much change with the sensible weather is expected heading into the
weekend with the sfc anticylone shifting from the Great Lakes Region
to over the Northeast.  High temps will be similar to Friday with
highs running about 5 degrees or so below normal for late
August.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
SCT/BKN diurnal fair weather cumulus in the 4-5 kft AGL range
now. The skies will quickly clear in the late afternoon/early
evening due to the strong subsidence with the sfc high. Some
radiational mist or fog is possible tonight with the best chance
in the climatological favor TAF sites of KGFL and KPSF where we
have IFR conditions forecasted mainly by 07Z-08Z. With fog
algorithm showing FG developing at KPOU as well, included IFR
conditions there starting at 08Z. FG should dissipate at all
sites by 12Z, yielding P6SM SKC conditions.

Outlook...

Monday Night: No Operational Impact. NO SIG WX.
Tuesday: Moderate Operational Impact. Breezy Chance of SHRA...TSRA.
Tuesday Night: High Operational Impact. Likely SHRA...TSRA.
Wednesday: Moderate Operational Impact. Chance of SHRA.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.

&&

.FIRE WEATHER...
High pressure building into the mid Atlantic region will bring
fair weather and seasonable temperatures on Sunday. A
southwesterly return flow around the high will bring mostly
sunny and warm weather Monday into Tuesday.

RH values will be near 100 percent at night. RH values will be
40 to 55 percent this afternoon and Monday afternoon.

Winds will be west at 5-15 mph today with a few gusts to 20
mph this afternoon. Winds will switch to southwest and again
diminish to 5-10 MPH or less tonight, increasing to around 15
mph Monday.

&&

.HYDROLOGY...
Widespread rainfall forecast during the next week is forecast to
be less than an inch. Some locally higher amounts are possible
in showers and thunderstorms later Tuesday into Tuesday night.
Only minor changes in stage and flow are forecast for larger
rivers and streams.

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.

&&

.EQUIPMENT...
While repairing the azimuthal gear box, radar technicians have
determined that the bull gear on KENX radar needs to be
replaced. This will require the radar to be out of service until
at least next Friday, August 25th.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...SND
NEAR TERM...SND
SHORT TERM...SND
LONG TERM...Wasula
AVIATION...OKeefe/Wasula
FIRE WEATHER...NAS
HYDROLOGY...NAS
EQUIPMENT...Staff



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