Albany, NY WFO Forecast Discussion

Forecast Discussion for ALY NWS Office
000
FXUS61 KALY 271049
AFDALY

AREA FORECAST DISCUSSION
National Weather Service Albany NY
649 AM EDT Mon May 27 2019

.SYNOPSIS...
High pressure will build in from southeast Ontario over
the region today with partly to mostly sunny conditions mainly dry
weather with seasonable temperatures.  Clouds will increase tonight
with the surface high moving eastward across New England, and a warm
front approaching from the south.  Periods of rainfall will occur
ahead of the warm front with weak disturbances moving along it
Tuesday into Tuesday night.  A brief period of dry weather may occur
Wednesday before another low pressure system moving along the front
brings showers and isolated thunderstorms once again late Wednesday
into Thursday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 649 AM EDT...A weak secondary cold front is approaching
northern NY and Lake Ontario associated with the upper trough
axis. The skies have cleared, but some clouds may increase in
the late morning with this feature. The 3-km NAMnest/GFS/ECMWF
has a few showers in the N to NW flow pop-up south of Lake
Champlain and the northern Adirondacks and drift southward into
the eastern Adirondacks/Lake George Saratoga Region. We
increased the cloud cover slightly this afternoon north of the
Capital Region and did add the isolated threat of a brief
shower or sprinkle in these areas.

It should be partly to mostly sunny most of the day with the
sfc anticyclone building in from the northern/eastern Great
Lakes Region, and southeast Ontario over NY and New England by
the afternoon. H850 temps lower to +6C to about +10C across the
region from north to south in the cold advection in the wake of
the front yesterday. H925 temps will be in the +13C to +17C
range with decent mixing and sunshine, we expect max temps this
Memorial Day to be near or slightly above normal and closer to
the warmer MAV MOS values with highs in the lower to mid 70s in
many of the valley locations with some upper 70s in the mid
Hudson Valley and NW CT. Expect 60s to lower 70s over the hills
and the mtns. A few upper 50s are possible over the high peaks
of the southern Greens and Adirondacks.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/...
Tonight...High clouds will be on the increase from the south and
west, as the sfc high moves eastward across New England, and
then offshore. Partly cloudy to mostly clear skies with light to
calm winds early on will allow for some radiational cooling in
the dry air mass. Some patchy frost is possible over the
southern Adirondacks (mostly northern Hamilton Co.) and the
southern Greens where some mid and upper 30s are possible. The
rest of the forecast area will be in the 40s to lower 50s. The
clouds will thicken and lower, as the warm front approaches
from the lower Great Lakes Region and west-central PA. Some
light rain may quickly move in west of the Hudson River Valley
before daybreak.

Tue-Tue Night...The mid and upper level flow becomes flat and
near zonal over the Northeast. A low-level baroclinic zone
sets-up between the retreating high and a wave moving in from
the Great Lakes Region toward upstate NY. The low-level jet
strengthens with a brief H850 +v-wind /southerly/ anomaly of
1-2+ STD DEVs above normal impacting the region TUE pm into TUE
night. PWATs increase +1 to +2 STD DEVs above normal based on
the 00Z GEFS. A cool stratiform rain is likely with isentropic
lift ahead of the front and wave. It will be a chilly afternoon
with temps struggling to get out of the 50s with some mid and
upper 40s over the northern mtns. A few lower 60s are possible
over the mid-Hudson Valley if locations south of Albany get
briefly in the warm sector. A very strong low-level inversion is
in place, but the latest NAM does indicate some decent elevated
instability from the Mohawk Valley/Capital Region south during
the afternoon into the early evening. The 00Z GFS is surpressed
further south. The 00Z NAM has MUCAPEs increase to 500-1000+
J/kg over the eastern Catskills, Mid Hudson Valley and portions
of SW New England. The low-level air mass looks fairly stable,
but there is enough elevated instability with decent deep layer
shear for isolated to scattered thunderstorms from the I-90
corridor south. SPC`s Day 2 has the Marginal Risk graze the
eastern Catskills, Mid-Hudson Valley and NW CT. This threat is
conditional the elevated instability is utilized with likely
hail the main threat. The 00Z NAM nest indicates a line could
get going when the wave or secondary weak impulse moves by.
Again, the threat looks minimal with the stable air mass.

The likely and categorical PoPs were lowered prior to midnight,
as the wave departs and the warm front sags back farther south
overnight over PA. Weak high pressure may also build in with
lows in the mid 40s to lower 50s. Some patchy fog may also
develop. Total rainfall looks to be in the 0.50-1.00" range with
any locally higher amounts tied to convection.

Wednesday...The flow aloft remains nearly zonal or quasi-zonal.
Low-level stratus may linger in the morning, but some subsidence
in the wake of the wave or waves may yield a fairly dry day
based on the latest 00Z GFS/NAM and to an extent to the 00Z
ECMWF. The CMC is the wettest with the next impulse moving along
the front. We went with slight chc PoPs for the morning west of
the Hudson River Valley, and slight to low chc during the
afternoon to stay in sync with the neighboring offices. Isolated
thunderstorms were kept in west of the Hudson River Valley. The
better synoptic forcing with the warm front and the next wave
looks to occur shortly before or just after nightfall. Highs
will still be slightly cooler than normal in the 60s to lower
70s for most of the region.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
The period starts out Wednesday night with a zonal flow aloft in
place across the region. A weak upper level disturbance and
associated surface trough could result in mainly scattered showers.
Instability appears to be rather minimal at this time, so will just
mention slight chance for thunder.

The pattern is expected to become slightly more amplified on
Thursday, as an upper level trough advances southeast across
southern Ontario/Quebec. In the low levels, warming should occur
well ahead of a surface cold front which would allow for at least
modest de-stabilization. There is uncertainty in terms of the low
level moisture, as the boundary layer flow looks to be W-SW and
PWAT/moisture flux anomalies are not forecast to be overly
impressive. Still, given the expected setup will mention showers
becoming likely by early Thursday evening with a chance of
thunderstorms. Some of the storms could become strong, but this is
highly dependent on the eventual instability.

Showers/storms should diminish either by late Thursday night or
Friday morning, as the system`s cold front pushes through. There are
model differences in the timing, with the ECMWF most progressive,
while the GFS is slower. Given the expected upper level pattern will
lean towards the more progressive scenario and only mention slight
chance pops for Friday. Temperatures look to be near normal, with
northwest winds resulting in comfortable humidity levels.

Tranquil conditions expected Friday night through Saturday with a
weak area of surface high pressure forecast to be in place and a
lack of any significant upper level short waves in the vicinity. Dry
weather may last into Sunday, although an approaching cold front
could result in scattered showers/thunderstorms depending on the
timing/placement. Overall, temperatures should continue to be near
normal as early June approaches.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
VFR conditions will prevail through the 24 hour TAF period
ending 12Z Tuesday, as high pressure builds eastward from SE
Canada. Mainly just SCT cumulus clouds will develop later this
morning into the afternoon, with bases around 5-6 kft AGL.
Coverage may increase enough for BKN cigs at KGFL later this
afternoon. High/mid level clouds will increase tonight, as a
wave of low pressure approaches from Great Lakes. Any rain
should hold off until after 12Z Tuesday.

Winds will be north-northwest around 5-10 kt, becoming light and
variable tonight.

Outlook...

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

&&

.FIRE WEATHER...
High pressure will build in from the northern Great
Lakes Region and southeast Ontario over the region today with
seasonable temperatures. Clouds will increase tonight with a
warm front approaching from the south. The warm front and weak
low pressure systems moving along it will bring rain and
isolated thunderstorms to the region Tuesday into Tuesday night
with more unsettled weather late Wednesday into Thursday.

The RH values will lower to 35 to 45 percent this afternoon, and
then recover to 85 to 100 percent Tuesday morning. Expect high
RH values in the damp air mass on Tuesday with minimum values of
65 to 75 percent.

The winds will be north to northwest at 5 to 15 mph this
afternoon, and the will be light to calm tonight. Northeast to
southeast winds of 5 to 15 mph are likely on Tuesday.

A widespread soaking rainfall is likely Tuesday into Tuesday
night.

&&

.HYDROLOGY...
No widespread hydrological issues are expected on the main stem
rivers the next several days.

Fair and dry weather is expected today through most of tonight
with high pressure in control.

A warm front with a few weak waves of low pressure moving along
it will bring areal rainfall amounts of a half an inch to about
an inch Tuesday and Tuesday night.

A brief break in the rainfall is possible early Wednesday.
However, the warm front and another low pressure system moving
along it will bring rain with some isolated to scattered
thunderstorms Wednesday into Thursday with variable rainfall
amounts of a tenth to a half an inch, except some locally higher
amounts in thunderstorms. The cold front will move through
Thursday night.

A drier air mass returns Friday into the first half of the
weekend. Any elevated within bankfull flows on the main stem
river should subside.

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

&&

.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.

&&

$$
SYNOPSIS...Wasula
NEAR TERM...Wasula
SHORT TERM...Wasula
LONG TERM...JPV
AVIATION...JPV
FIRE WEATHER...Wasula
HYDROLOGY...Wasula

NWS ALY Office Area Forecast Discussion