Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 202332
AFDALY

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

.SYNOPSIS...
High pressure building into the mid Atlantic region will bring fair
weather and seasonable temperatures through tonight. 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 6 AM MONDAY MORNING/...
As of 710 pm, tranquil conditions across the area as a high
pressure ridge continues to expand into the forecast area.
Little changes needed to going forecast.

As of 4:36 PM...mostly sunny and fair weather continues across
the Albany Forecast Area. Temperatures range from the low 70s
in the higher terrain to around 80 in the Mid Hudson Valley.
Winds are generally from the west to northwest at 10 to 15 MPH.
Dewpoints have dropped into the 50s most locations. This,
coupled with the breeze, is making for a pleasant late summer
day. Clouds and breeze will diminish towards sunset with loss
of sun`s heating.

Skies are forecast to be mostly clear overnight. With light
wind and clear skies, good radiational cooling expected and this
will lead to patchy fog, some of it dense across the area. Lows
tonight in mainly in the 50s to around 60.

&&

.SHORT TERM /6 AM MONDAY MORNING 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 over most of our area. Western zones may
see an increase of clouds for the second half of the event,
hopefully after the peak. Highs upper 70s to upper 80s.

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. At this time, most of our area is in a slight risk
for severe weather on Tuesday with southeastern areas in a
marginal risk.

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 be 5.5 to 6.5C.

There should be enough instability, shear and upper dynamics
for the potential for severe thunderstorms Tuesday afternoon and
evening. With strong dynamics and lift associated with the
approaching cold front, storms may rumble around past midnight.
Lows Tuesday in the 60s. Highs Tuesday in the 80s to low 90s.

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. Lows Tuesday night
upper 50s to around 60 in the northwest to upper 60s southeast.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
The extended portion of the forecast will feature seasonably cool
and dry conditions with freedom from precipitation from Wednesday
night on.  A well-pronounced cold front will slide through our
forecast area Wednesday morning. Elongated high pressure down
across the Canadian and U.S. plains will expand eastward to
additionally encompass the Great Lakes and New England by
Thursday, the mid- Atlantic by Friday and the deep south by
Saturday, while retreating eastward from the Plains. The high
will continue to dominate through the weekend across Quebec and
the Canadian Maritimes, extending down the eastern seaboard and
the eastern Great Lakes to the Gulf Coast.

High temperatures on Wednesday will average about 10 degrees cooler
than Tuesday, with readings on Thursday reaching only into the 60s
and 70s.  Northern high peaks may not crack 60 degrees on Wednesday.
Little diurnal change in high temperatures is expected beyond
Thursday, with high peaks in the Greens possibly not cracking 60
degrees over the weekend.  Low humidities like we haven`t seen all
summer will be a significant feature of this entire period.  Low
temperatures Wednesday night will range from around 50 degrees in
the high peaks...to near 60 degrees across the far southern zones.
The rest of the nights will average a few degrees cooler...with lows
generally in the upper 40s to mid 50s range.

&&

.AVIATION /23Z SUNDAY THROUGH FRIDAY/...
Main aviation concern in the period is fog/mist potential
tonight. High pressure expanding into the region and clear skies
will set the stage for good radiational cooling conditions.
Moisture should be shallow with a fairly dry airmass, but still
enough moisture in the boundary layer to support fog/mist
potential. Kept inherited IFR mention at KPSF/KGFL/KALB but
added some temporal resolution, including a TEMPO for dense fog
after 08Z at climatologically favored KGFL/KPSF. Any fog should
burn off quickly after sunrise Monday, leaving just a few high-
based cumulus and perhaps patches of cirrus from time to time.

Winds will become light and variable to nearly calm overnight,
increasing to 5 to 10 kt out of the southwest after sunrise
Monday.

Outlook...

Monday Night: No Operational Impact. NO SIG WX.
Tuesday: Moderate Operational Impact. 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.
Thursday Night: No Operational Impact. NO SIG WX.
Friday: No Operational Impact. NO SIG WX.

&&

.FIRE WEATHER...
High pressure building into the mid Atlantic region will bring fair
weather and seasonable temperatures through tonight. 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.

RH values will be near 100 percent at night. RH values will be
45 to 60 percent Monday afternoon and 50 to 60 percent on Tuesday
afternoon.

Winds will become light and variable after sunset this evening.
Winds will increase to around 15 mph Monday from the southwest.
South to southwest winds at 5-10 MPH are forecast Monday night.

&&

.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/Thompson
SHORT TERM...SND
LONG TERM...ELH
AVIATION...Thompson
FIRE WEATHER...SND
HYDROLOGY...SND
EQUIPMENT...


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