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980
FXUS61 KALY 182318
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
718 PM EDT Wed Jul 18 2018

.SYNOPSIS...
High pressure will build across the region today through
Friday, bringing fair weather with much less humid conditions.
Unsettled conditions may return over the weekend as a frontal
system slowly approaches from the west.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Clear sky and temperatures cooling. Few changes to the forecast
needed if any through tonight. Previous AFD has a few more
details and is below...

High pressure building toward the area will bring clear skies
tonight with temperatures much cooler than the past several
nights. Dew points are down in the 40s north of the Mohawk
Valley already as of late this afternoon, with 50s farther
south. We are expecting overnight lows tonight to reach the 40s
in many cooler locations along and especially north of I-90
tonight with lower to mid 50s elsewhere. Patchy fog will develop
in many of the usual locations, mainly at lower elevations near
a water source.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
High pressure will dominate the weather pattern into Saturday
with sunny warm days and clear cool nights. Temperatures will
recover to the lower 80s at lower elevations on Thursday then
into the mid 80s on Friday. Overnight lows will once again be
below normal Thursday night; the coldest locations across the
north country will reach the 40s with 50s elsewhere. Once again
some patches of fog will develop early Friday morning in the
valleys.

The pattern will begin to change on Saturday as an unseasonably
strong mid-to-upper level low pressure area moves east from the
midwest and turns the mid level flow into the south along the
east coast by Saturday afternoon. Low pressure developing off
the mid- Atlantic coast will spread clouds across the area from
the south with rain spreading north toward the area during the
afternoon. At this point it appears that the best chance for
rain will hold off until Saturday night. Models are in good
agreement with this scenario and confidence is above normal for
a day 3 to 4 forecast.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
There is an increasing consensus that an upper low will develop in
the OH Valley and Great Lakes while upper energy and moisture in the
SE U.S. rotates around the eastern periphery of the cyclonic upper
flow into the northeastern U.S.  This upper energy looks to be timed
for Saturday night and Sunday with moisture and a boundary layer
wind maximum tracking north from offshore the Mid Atlantic into New
England and eastern NY. The upper energy, subtropical moisture and
low level wind energy should support showers likely and scattered
thunderstorms Saturday night into Sunday. There could be some
locally heavy rain but with the dry conditions in many places this
summer, it should be a beneficial rain in most cases.  Flood
potential will have to be watched though as we get closer based on
the increasing tropical moisture over our region through the
beginning and middle of next week.

Once the upper energy and low level forcing exit later Sunday, there
is a general consensus that the upper low in the OH Valley slowly
weakens, retrogrades west and south while upper ridging in the
Atlantic builds north and west into our region. As upper heights
rise over our region and weak zonal upper flow sets up, a
southwest/northeast oriented zone of deep tropical moisture is
expected to be relatively stationary over our region, leftover from
the upper low and anchored on the northern periphery of the
developing upper ridging in the eastern U.S.  So, with tropical
moisture in place, diurnal scattered thunderstorms with locally
heavy rain are possible each afternoon, Monday through Wednesday,
with slowly decreasing coverage each night.

Highs Sunday in the 70s to around 80.  Highs Monday through
Wednesday in the lower to mid 80s but upper 70s to around 80 higher
terrain. Lows Sunday night, Monday night and Tuesday night in the
humid and uncomfortable upper 60s to lower 70s but mid 60s higher
terrain.  High temperatures cold be warmer Monday through Wednesday
if there are breaks in the clouds each morning and early afternoon
before the storm develop through the afternoon, which could be the
case since boundary layer flow looks to be southwest and downslope
in some areas.

&&

.AVIATION /23Z WEDNESDAY THROUGH MONDAY/...
High pressure in control of the weather through Thursday. Few
clouds if any through Thursday but some fog is possible at KPSF
and KGFL after midnight ending around daybreak. Otherwise VFR
conditions.

Winds will be west to north at 10 Kt or less this evening
diminishing to near calm by daybreak. Winds variable at 6 Kt or
less Thursday.

Equipment note...at KPSF electrical work is ongoing on the
field. Power has been cut to ASOS. Therefore TAF is issued as
AMD NOT SKED.

Outlook...

Thursday Night: No Operational Impact. NO SIG WX.
Friday: No Operational Impact. NO SIG WX.
Friday Night: No Operational Impact. NO SIG WX.
Saturday: No Operational Impact. NO SIG WX.
Saturday Night: Low Operational Impact. Slight Chance of SHRA.
Sunday: Moderate Operational Impact. Chance of SHRA...TSRA.
Sunday Night: Moderate Operational Impact. Chance of SHRA...TSRA.
Monday: Moderate Operational Impact. Chance of SHRA...TSRA.

&&

.FIRE WEATHER...
High pressure will build across the region today through
Friday, bringing fair weather with much less humid conditions.
Unsettled conditions may return over the weekend as a frontal
system slowly approaches from the west.

RH will fall to 30-40 percent this afternoon and again Thursday
afternoon, and recover to 80-100 percent late tonight, with
areas of dew formation possible.

Winds will be from the north to northwest at 10-20 mph today,
then become light/variable tonight. Winds will be mainly from
the north to northwest at 5-10 mph Thursday.

&&

.HYDROLOGY...
Most of area received much needed rainfall, with some areas
receiving heavy rains through Tuesday evening. This allowed for
some very minor river rises of generally less than 2 feet.

Dry weather is expected through at least Saturday.

A slow moving frontal system approaching from the west, along
with a very moist airmass in place, could lead to frequent
showers and thunderstorms, some with locally heavy downpours for
Sunday through at least the middle of next 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.
NY...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...KL
NEAR TERM...MSE/NAS
SHORT TERM...MSE
LONG TERM...NAS
AVIATION...NAS
FIRE WEATHER...KL
HYDROLOGY...KL