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000
FXUS61 KALY 200238
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
1038 PM EDT Fri Apr 19 2019

.SYNOPSIS...
Showers will become widespread overnight into Saturday morning.
Heavy rain and scattered thunderstorms may result in flooding
along rivers, streams, and in low lying poor drainage areas. The
showers will taper off during the day Saturday with cloudy,
damp weather and mild temperatures for the rest of the weekend.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Flood watches remains in effect. A complex system will impact the
region bringing widespread rain to the area with locally moderate
and heavy rainfall along with scattered thunderstorms. An upper
level low has cut off at the base of a deep trough over the
Tennessee Valley and will gradually move to the Ohio Valley
overnight.

As of 10:38 PM EDT, Scattered showers across forecast area most
numerous over southern Adirondacks, eastern Catskills, southern
Berkshires and Litchfield Hills. Some showers developing on
upglide over shallow cold front over southern Adirondacks and
Lake George area have been small but high reflectivity indicates
small heavy downpours. Most of heaviest rain remains west of
our forecast area. Maximum rainfall totals so far 0.7 inches at
Cold brook in herkimer County and 0.6 inches at Claryville in
southwest Ulster County. Occluded front will approach from
southwest over next couple of hours and rainfall should increase
later tonight. Update based on ongoing trends in satellite,
radar and observations.

Previous...
Southerly flow between the deep trough to our west
and ridging over the Atlantic Ocean is transporting Gulf
moisture northward into the region. Precipitable water values
are expected to rise to around 1.50 inches tonight and a strong
low level jet will move into the region. Guidance indicates
convective elements move into and across the area which will
result in locally heavy rainfall. If there is any training this
will increase the threat of flooding. A nearly stationary
boundary located across the eastern Great Lakes and far northern
New York is expected shift southward some overnight. This
boundary will provide a focus for heavier rainfall across the
northern Country into the southern Adirondacks.

It will be mild tonight with lows mainly in the 50s and 60s.

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/...
The upper low will only move gradually eastward from over the
Ohio Valley to the mid-Atlantic over the weekend as the
surface low weakens over the region.

The focus for heavier rainfall shifts New England on Saturday
as the low level jets shifts to our east. The steady rain will
taper off as the day progresses holding on into late in the day
across western New England. The bulk of the rainfall is expected
during the morning with lighter amounts in the afternoon. We
will be in the warm sector with breezy southerly winds and are
expecting highs in the 60s to lower 70s.

Lingering showers Saturday night with cloudy, damp and mild for
the remainder of the weekend as the upper low passing just to
our south. Chances for showers are expected to be back on the
increase Sunday night as activity moves in from New England as
the upper low begins to shift northeastward.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Our vertically stacked, mature cut-off low will continue to impact
our region on Monday as an Omega Block in the western Atlantic will
prevent it from progressing eastward. In fact, as the cut off low
inches off the East Coast, we notice it deepens with moisture from
the sub-tropical moisture feed from the Fri-Sat event getting re-
entrained into it. We also notice a TROWAL developing on its
northwest flank which when combined with deformation dynamics should
enhance rainfall amounts in western New England into parts of
eastern NY (especially east of the Hudson). Lapse rates in this
region also steepen to near 6C/km so we added thunder. The ECMWF
continues to be the most robust with QPF amounts showing over an
inch along and west of the CT River Valley while the GFS and CMC
trended wetter compared to previous runs but are not nearly as wet.
For now, placed widespread chance POPs with the highest POPs in
western New England.

Further upstream, a northern stream shortwave trough Ontario digging
towards the Upper Great Lakes should be the kicker needed to push
our slow moving mature cut off low out to sea on Tuesday. Strong
subsidence in the wake of the cut off should strength a shortwave
ridge building inbetween our exiting low and approaching
trough. This should lead to a warm and mainly dry Tuesday with
850mb isotherms climbing to +7C to +10C leading to high
temperatures in the 70s up the Hudson Valley. Our northern
stream trough will be on the leading edge of a large scale cool
air mass associated with a Canadian high. As this surface cold
front pushes southeastward towards the the Saint Lawrence River
Valley, a weak surface low in the Midwest looks to ride along
it. Model guidance has once again trended wetter than previous
runs (again trending towards the ECMWF) and we followed suite,
placing widespread shower chances across the region for
Wednesday.

The spread in model guidance then increases by Thursday/Friday. The
ECMWF shows our cool Canadian high pushing in the wake of our
exiting surface low and thus giving us a dry yet seasonably cool
Thursday. On the other hand, the GFS and CMC-NH paint a much
gloomier picture showing the warm front associated with our
surface low getting stuck along the Greens/Berkshires and our
Canadian high becoming positioned in eastern Quebec. This would
be a textbook set- up for New England and eventually areas along
and east of the Hudson River to get "back doored" with the much
cooler, marine influence air mass. Favored this output and
lowered temperatures on Thursday to be in the 50s with low 60s
in the western Mohawk Valley and Schoharie Valley which
typically stay mild in these situations. Also continued to show
slight chance of showers.

All members of the global guidance show another system from the
Ohio Valley potentially impacting our region for the end of the
work. Therefore, continued the slight chance POP mention but
did not go any higher given this the day 8 forecast.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...
Radar shows areas or rain moving south to north across the area.
KGFL reporting light rain but still VFR. KALB has MVFR
visibility in moderate rain but ceiling still VFR. VFR at KPOU
and KPSF.

Showers will start to increase in coverage across the region
and spread from southwest to northeast across the area
overnight. Flying conditions will lower to MVFR all TAF sites
for both vsby/cigs within on and off showers. Some IFR
conditions are possible overnight all TAF sites especially
within any thunderstorms. The best timing window for any
thunderstorms right now appears to be 02z-06z, but this may need
to be refined in future updates. Winds overnight will continue
to be southerly, generally around 10 to 15 kts with guts to 30
kts.

Showers will start to decrease in coverage tomorrow morning,
especially for KALB/KPOU. A return to VFR conditions may occur
at KALB/KPOU by mid to late morning on Saturday, but not till
late in the day at KGFL and KPSF. Winds on Saturday will be
southeast at 5 to 10 kts at KGFL, but will probably remain
southerly at the other sites at 10 to 15 kts with gusts to 25
kts.

Outlook...

Saturday Night: Moderate Operational Impact. Chance of SHRA.
Sunday: Low Operational Impact. Slight Chance of SHRA.
Sunday Night: Moderate Operational Impact. Chance of SHRA.
Monday: Moderate Operational Impact. Chance of SHRA.
Monday Night: Moderate Operational Impact. Chance of SHRA.
Tuesday: Moderate Operational Impact. Chance of SHRA.
Tuesday Night: Moderate Operational Impact. Chance of SHRA.
Wednesday: Moderate Operational Impact. Chance of SHRA.

&&

.FIRE WEATHER...
Showers will become widespread this evening then continue through
the overnight. The showers will taper off Saturday with cloudy, damp
weather and mild temperatures for the rest of the weekend.

&&

.HYDROLOGY...
The flood watch for areas north of I-90 is in effect for this
evening through Sunday morning. For the Berkshires and northwestern
Connecticut a watch is in effect tonight into early Saturday
afternoon. As for the rest of the area, a flash flood watch is in
effect for overnight through Saturday.

Showers will become widespread this evening then continue through
the overnight into Saturday morning. Locally heavy rain and
scattered thunderstorms may result flooding along rivers,
streams, and in low lying poor drainage areas. In addition, a
lingering snowpack at the highest elevations of the Adirondacks
and southern Green Mountains will also be contributing to the
runoff across the southern Adirondacks, Lake George Region and
southern Vermont. The showers will taper off Saturday however
chances for showers will linger through the weekend.

Please visit our Advanced Hydrologic Prediction Service /AHPS/
web page for specific area rivers and lakes observations and
forecasts.

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch from 2 AM EDT Saturday through Saturday evening
     for CTZ001-013.
NY...Flash Flood Watch through Saturday afternoon for NYZ047>054-
     058>061-063>066.
     Flood Watch through Sunday morning for NYZ032-033-038>043-
     082>084.
MA...Flood Watch from 2 AM EDT Saturday through Saturday evening
     for MAZ001-025.
VT...Flood Watch through Sunday morning for VTZ013>015.

&&

$$
SYNOPSIS...IAA/SND
NEAR TERM...IAA/SND
SHORT TERM...IAA
LONG TERM...Speciale
AVIATION...SND
FIRE WEATHER...IAA
HYDROLOGY...IAA