National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

-- Discussion containing changed information from previous version are highlighted. --
964
FXUS61 KALY 261057
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
657 AM EDT Wed Jul 26 2017

.SYNOPSIS...
High pressure will briefly build into the region today with
improving conditions. However, an approaching frontal system
will bring some showers and thunderstorms for Thursday, but
clearing conditions are expected for the weekend.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 625 AM EDT...Patchy dense fog across the region as an SPS
was issued to highlight this hazard. Enhanced experimental GOES
16 satellite data continues to clearly depict fog lining up
along the rivers and deeper valleys. With sunrise, conditions
should improve rather quickly this morning. Otherwise, low and
mid level clouds were evident along the I81 corridor as we will
keep a partly sunny to mostly sunny forecasts at this time.

Prev Disc...Impressive experimental GOES 16 nighttime
microphysics advanced channels revealing the westward advecting
stratus deck and within an hour of its passage, lower level
stratus and fog formation, especially in the valley and near
bodies of water. So clouds west of the Hudson and a mainly clear
start to the east with patchy dense fog. All short term NCEP
Model suite guidance and global models suggest along the I81
corridor an enhanced region of low level moisture (H850 and
below). As the surface high slides east of the region, this
moisture does return back to the region but too what extent is
not too clear. Given the advective nature and July sunshine, we
will opt for a partly sunny forecast. Clouds may be a bit more
across the higher terrain with daytime heating as high
temperatures should easily be about 10 degrees warmer with
mainly 70s with around 70F for the higher terrain.

Clouds seen upstream from the convection through the upper
Mississippi River Valley through the upper Great Lakes will
advect into the northern portions of the region later this
afternoon.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY NIGHT/...
The aforementioned clouds upstream will advect in across the
remainder of the region tonight as frontal boundary drifts
southeastward. Timing is rather similar with the frontal
placement in the vicinity of the St Lawrence Valley around or
shortly after midnight. This will enhance the chances for
showers across the Dacks, Lake George Saratoga Region and
southern VT. As the mid level westerlies increase, this too
advects in additional mid level instability where Showalter
values drop toward 0C by 12Z Thursday as we will continue with
the slight chance for thunderstorms. Overnight lows will be a
bit milder than recently with mainly 60s expected as dewpoints
climb toward 60F.

Per the latest coordination messages and outlooks from SPC, all
of our region is within a `marginal risk` for severe
thunderstorms on Thursday. While modest shear will be in place
of 25-35kts, main question will be the degree of insolation and
resultant instability. Modified parcels point toward SBCAPES
over 1000 J/KG yet lapse rates were near or just below 6 C/Km.
Given a slow dropping wet bulb zero heights and relative speed
shear, we will enhance the thunderstorm wording to include gusty
winds and small hail. Highs Thursday could climb toward 80F for
valley locations with otherwise 70s elsewhere.

Thursday night there is a growing consensus that this frontal
zone will track rather quickly from northwest to southeast
through the evening hours. This would suggest holding onto some
PoPs/Wx for southern zones earlier on then drying conditions for
the remainder of the overnight period as surface ridge builds in
from central Canada. So clearing skies from north to south
through the night as overnight lows from the 50s from the Dacks
to 60s for valley locations.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
The upper pattern becomes complex through the weekend with an
increasing consensus that an upper low develops south of our region
Friday and tracks along or just south of Long Island late Friday
into Saturday. Most sources of guidance and ensembles keep the
deeper moisture and most of the extensive cloud cover just south of
our forecast area. However, the northern extent of clouds and
isolated showers could get into the mid Hudson Valley and NW CT
Friday and Friday night before high pressure builds into our region
from Canada and the Great Lakes late Saturday.  Highs Friday and
Saturday in the mid to upper 70s but cooler in higher terrain.

Mean upper troughing remains just east of our region Sunday and
Monday with some upper ridging building east from the Great Lakes
north of the exiting upper troughing.  The upper ridging will aid in
some slow gradual warm advection. So, dry weather and more sun than
clouds Sunday and Monday as long as upper troughing does exit just
to the east as guidance suggests. Highs Sunday in the upper 70s to
around 80 but lower 70s higher terrain. Highs Monday in the lower to
mid 80s but mid to upper 70s higher terrain.

By Tuesday-Wednesday there is a loose consensus for the next weak
cold front to drop south out of Canada with little moisture and weak
low level forcing.  So, intervals of clouds and sun with isolated to
scattered showers and thunderstorms may be possible.  Highs Tuesday
and Wednesday in the lower to mid 80s but mid to upper 70s higher
terrain.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
Patchy dense fog is currently impacting the area this morning
with LIFR conditions at all TAF sites except POU. This fog
should lift/burn off by around 13Z this morning. VFR conditions
should then prevail through the rest of the forecast period.
Some showers may be possible at the tail end of the period as
the next cold front approaches from the north and west.

Outlook...

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

&&

.FIRE WEATHER...
No fire weather related issues expected, as our area saw a
wetting rain recently. RH values will fall to 40 to 70 percent
on Wednesday with very light winds. The next chance for rain
showers and thunderstorms will be on Thursday.

&&

.HYDROLOGY...
Mainly dry weather is expected through today with breaks of
sunshine. The next frontal system will return the chance for
some showers and thunderstorms on Thursday into Thursday
evening. Model guidance is starting to come together that it
should be through by Friday morning, so dry weather looks to
return for Friday into the weekend.

Rainfall amounts will be variable on Thursday due to the track
of showers/thunderstorms, but widespread heavy rainfall is not
expected. Aside from a brief burst of heavy rainfall from a
thunderstorm, no flooding issues are anticipated with this
rainfall.

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...BGM
NEAR TERM...BGM
SHORT TERM...BGM
LONG TERM...NAS/JVM
AVIATION...JVM
FIRE WEATHER...Frugis/BGM
HYDROLOGY...Frugis/BGM