Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 010716
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
316 AM EDT Mon May 1 2017

.SYNOPSIS...
A warm front will increase the threat of isolated to scattered
showers into early today as it slowly lifts north of the region. A
warm and more humid air mass will be over the region today, but a
cold front will bring widespread showers and a chance of
thunderstorms late in the afternoon into Tuesday morning.

&&

.NEAR TERM /THROUGH TUESDAY/...
Surface warm front remains well to the southwest of the forecast
area over northeastern Ohio and western Pennsylvania. As a
result temps will be tricky today. For now expect most valley
areas will reach into the low to mid 70s, however it will be
cooler over western New England with highs only in the mid to
upper 60s. SPC has placed FA in either slight risk or enhanced
risk for today and with good reason. MLMUCAPES across western
zones rise into the 500-1000 J/KG range with lower values
further east. In addition ML Bulk Shear quite impressive over
40 kts crossing the forecast area this afternoon into this
evening.

There is a general consensus for the cold front to track through
our region Monday night and the early morning hours of Tuesday.
There will be considerable instability late Monday afternoon and
evening, moderating later Monday night. The low level flow will
be relatively strong, so some thunderstorms could approach
severe criteria, especially along and west of the Hudson
Valley. Expect lows Monday night to be in the upper 40s to
around 60.

Cold advection spreads across the region Tuesday and the upper
dynamics advance through the Great Lakes toward our region.
Cooling aloft and the proximity of the boundary layer thermal
gradient building east and south will support scattered showers
in many areas through the day Tuesday. There should be some
break in the clouds in between showers. So, highs Tuesday in
the 60s to lower 70s but some mid 50s northern areas.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Tuesday night into Wednesday, mid/upper level cyclonic flow will
persist, likely leading to the persistence of a good deal of cloud
cover. Forecast models depict H850 cold air advection during the
period, with temps bottoming out around -3C during the day
Wednesday. Steepening low-level lapse rates, midlevel moisture, and
subtle shortwave disturbances rotating through will team up to
provide some showers, likely most widespread across the western
Adirondacks where some convergence to the lee of Lake Ontario and
some upslope contributions are likely. With the expected cloud cover
and cool airmass, highs Wednesday will likely come up several
degrees short of normal. Breezy conditions will continue as well as
a healthy pressure gradient is maintained between a surface low over
the Canadian maritimes and high pressure expanding across the lower
Great Lakes and Ohio Valley.

Wednesday night, upper level height rises are progged with the
attendant surface anticyclone tracking overhead. This should lead to
a clearing trend and some chilly overnight lows. Upper and midlevel
clouds look to increase late ahead of the next system.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
Medium-range deterministic models and GEFS ensembles in fairly good
agreement with the general pattern over the long term. A deep trough
over the lower Mississippi Valley at the start of the period will
close off and lift toward the lower Great Lakes by Friday, and
eventually become centered near the northeastern US by the weekend.
This system looks to entrain some Gulf moisture, with PWAT values
AOA 1 inch transported into the local area by Friday. As it stands
now, the moisture plume looks progressive enough to spare our
forecast area a prolonged heavy rain event, but this will be
something to monitor as forecast solutions have been known to be
variable over time when dealing with cutoff lows. At any rate, the
most probable time frame for steady precipitation looks to be
Thursday night into Friday, when isentropic lift and moisture
advection are maximized.

Friday night into the weekend, the upper low will be drifting across
the Great Lakes region or the northeastern US/southeastern Canada.
The exact placement of the upper low will determine precip chances,
but for now model consensus favors a cloudy, cool, and showery
period, but not a complete washout given the tropical moisture
plume`s eastward displacement.

&&

.AVIATION /07Z MONDAY THROUGH FRIDAY/...
|A warm front will approach the region overnight, and should lift
north and east of the TAF sites this morning. A cold front will
approach from the west tonight.

Conditions overnight are expected to gradually deteriorate,
mainly due to lowering CIGS, from initial VFR levels into MVFR
between 06Z-08Z/Mon. Mainly MVFR CIGS are expected to prevail
through Monday, although a few breaks in the clouds and brief
periods of VFR are possible in the afternoon.

Some patchy drizzle/fog could form between 08Z-14Z/Mon, esp at
KPSF and KPOU. Again, mainly MVFR conditions are possible,
although can not completely rule out brief IFR conditions.

As for showers, it appears most should remain well north and
west of the TAF sites through 22Z/Mon. After this time the
threat for showers and some thunderstorms will start to
increase.

Winds should become southeast overnight, and may increase at
KALB to 10-15 KT with gusts up to 25 KT after midnight.
Elsewhere, expect speeds to generally remain below 12 KT through
daybreak.

On Monday, winds should be southeast to south at 8-12 KT, with
some gusts up to 25 KT possible.

Low level wind shear has been included in TAFs for KGFL and
KPOU overnight into Monday, as sfc winds remain light from the
east/northeast at 5-10 KT, while winds around 2000 FT AGL
increase from the south to 30-40 KT.

Outlook...

Monday Night: High Operational Impact. Breezy Definite SHRA...TSRA.
Tuesday: Moderate Operational Impact. Breezy Chance of SHRA.
Tuesday Night: Low Operational Impact. Slight Chance of SHRA.
Wednesday: Moderate Operational Impact. Breezy Chance of RA.
Wednesday Night: Low Operational Impact. Slight Chance of RA.
Thursday: Moderate Operational Impact. Chance of RA.
Thursday Night: High Operational Impact. Definite RA.
Friday: High Operational Impact. Likely RA.

&&

.FIRE WEATHER...
A warm front will increase the threat of isolated to scattered
showers into early today as it slowly lifts north of the region. A
warm and more humid air mass will be over the region today, but a
cold front will bring widespread showers and a chance of
thunderstorms late in the afternoon into Tuesday morning.

The RH values will fall only to 60 to 80 percent today with
scattered showers and thunderstorms late Monday afternoon. RH
values will be 85 to 100 percent tonight and drop to 40 to 75
percent Tuesday. Winds will be southeast to south today at 10
to 15 mph. Winds shift to west late Monday night at around 15
mph and become northwest at 10 to 20 mph Tuesday.

&&

.HYDROLOGY...
A strong cold front will cross through the region late Monday
afternoon into Tuesday morning. This front may allow for some
locally higher rainfall totals due to widespread showers and a
chance of thunderstorms in a more humid air mass. No problems
are anticipated on the main stem rivers. Rainfall amounts will
range from a quarter of an inch southeast to over an inch
northwest over the Hydro Service Area with some locally higher
amounts in thunderstorms. Ponding of water on roadways or low
lying areas and poor drainage flooding within urban areas will
be possible.

Showery and unsettled weather continues Tuesday into Wednesday
with additional light rainfall amounts of a few hundredths to a
quarter of an inch.

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...11/NAS
NEAR TERM...11/NAS
SHORT TERM...NAS
LONG TERM...Cebulko/KL
AVIATION...KL/11/NAS
FIRE WEATHER...11/NAS
HYDROLOGY...11/NAS



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