Area Forecast Discussion
Issued by NWS Albany, NY

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FXUS61 KALY 271729
AFDALY

Area Forecast Discussion
National Weather Service Albany NY
1229 PM EST Mon Feb 27 2017

.SYNOPSIS...
High pressure will briefly be in control of our weather today
with temperatures warming back to above normal readings. The
next chance of rain and snow showers will be late tonight into
Tuesday with a warm front and low pressure moving into the
Midwest.

&&

.NEAR TERM /THROUGH TONIGHT/...
Some high clouds tracking across southern areas but only
filtering the sun. South to southwest winds, warm advection and
sunshine will help temperatures get to the 50s in many areas but
40s in northern areas this afternoon. Just minor adjustments to
the forecast through this afternoon based on current data and
trends.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
A low pressure system will eject out of the plains Tuesday and
lift through the Great Lakes along the US/Canadian border on
Wednesday. Energy embedded within the upper level flow will
move through the area during this time, providing chances for
rain. However, timing these pieces of energy/rain chances is
very difficult given the model discrepancies. Notably, the GFS
tracks the surface low further north and is faster than the
ECMWF, especially with the precip. So that being said, used a
blended approach with pops/QPF to keep rain chances in the
forecast Tuesday morning, increasing throughout the day.

On Wednesday, strong upper level energy and surface cold front
approach the region. Some question as to how quickly
moisture and upper dynamics approach, which will determine how
much warming we will see Wednesday. If southwest boundary layer
flow can maximize downsloping effects, then temps could easily
warm into the mid 60s but will have to watch out for cloud cover
inhibiting this. For now, have gone above guidance, warming
temperatures into the upper 50s to mid 60s.

In terms of thunderstorm potential on Wednesday afternoon, model
soundings show increased surface based instability during the
afternoon. But in order to tap into this will depend on the
timing and track of the surface low and cold frontal passage, as
well as cloud cover. So for now, have included a chance of
thunder in the forecast. SPC has also put the forecast area in a
marginal risk of severe weather for the Day 3 outlook. Heavy
rain and gusty winds will be the primary threat.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A mean longwave trough will prevail much of the extended forecast
period with a shift to mid and upper level zonal flow late next
weekend. Overall, the extended will begin active with a strong cold
front and a deepening cyclone moving into northern New England with
windy and cold conditions by THU, and most of the long term is
unsettled heading into the weekend.

Wed night into Thursday...the medium range guidance and ensembles
are converging on a cold front moving across the forecast area Wed
night with a slight chc of thunderstorms early in the evening and
showers along the frontal axis and the upper level trough.  The air
mass will be warm and humid for early March ahead of this cold front
with dewpoints in the 40s and lower 50s.  PWATS will be 1 to 2+
standard deviations above normal according to the latest 00Z GEFS.
H850 temps will also be 1 to 2 standard deviations above normal
ahead of the front. Showalter stability values will be in the 0 to
-1C range ahead of the front in the early evening with some MUCAPE
generally less than 250 J/kg according to the latest 00Z GFS. Strong
cold advection kicks in, as a cyclone rapidly deepens and
intensifies moving along the St Lawrence River Valley Wed night as
possibly a sub-980 hPa cyclone over northern ME by 12Z/THU according
to the 00Z ECMWF.  The 00Z GFS is faster and even stronger with a
971 hPa cyclone over the Gulf of St Lawrence by 12Z/THU.  Much
colder air will filter into the region and it will become windy late
Wed night into THU.  Wind gusts right now are forecasted to be in
the 30-45 mph range, but wind advisory winds may be possible, so we
will continue to mention in the HWO for THU.  Upslope snow showers
will persist on THU in the wake of the front and cyclone.  Some
light snow accums are possible over the western Adirondacks and
southern Greens.  Lows Wed night will be in the mid 20s to mid 30s
north  and west of the Capital District...with upper 30s to lower
40s from there south and east. Highs will only in the upper 20s to
upper 30s north and west of the Tri Cities on THU, and lower to mid
40s or so south and east with blustery northwest winds.

Thu night into Fri...There is quite a bit of model disparity on what
to do with a clipper like cyclone approaching in the northwest flow
Thu night.  The ECWMF takes the clipper and short-wave south and
west of most of the region with light snow possibly from the Capital
Region south and west.  The GFS is bullish with the short-wave and
weak wave in terms of the amount of QPF and its track along the NY-
PA border.  It would be a light to moderate snow event.  Alas, the
model superblend and GEFS/ECMWF/WPC consensus is only for slight to
low chc pops with some light snow or scattered snow showers.  We
will continue to monitor this system and keep pops in the slight to
low chc range.  Lows will be mainly in the teens to 20s in the
chilly air mass THU night with a few single digits over the southern
Greens and southern Dacks...with highs in the 20s to mid 30s in the
wake of the system with a few teens over the higher elevations.
These temps will be a shade below normal with wind chills in the
single digits to teens.

Fri night into Saturday...Arctic high pressure settles in over the
region.  Wind chills could be from 10 above to 10 below zero Fri
night before the winds settle down towards daybreak.  Lows will be
in the single digits and teens, and some multibands of lake effect
snow in the northwest flow may graze the western Mohawk Valley,
Schoharie Valley and western Adirondacks early in the evening.  The
weekend opens dry and cold with temps below normal by 5 to 10
degrees.

Saturday night into Sunday...the surface anticyclone passes south
and east of the Northeast off the Mid Atlantic Coast.  A return flow
of milder air impacts the region with a warm front approaching from
the lower Great Lakes Region.   The mid and upper level flow becomes
flatter, and temps rebound above normal on Sunday.  Some scattered
snow/rain showers are possible to close the weekend in the warm
advection regime.

&&

.AVIATION /18Z MONDAY THROUGH SATURDAY/...
Mid/high clouds continue to filter into the region from the
southwest today. Expect cloud bases to gradually lower through
the TAF period, but still remain VFR. A few light rain or snow
showers are possible after 08Z as a warm front lifts into the
region, but confidence is not high enough for an explicit
mention attm. Will continue with VCSH 08-15Z.

Winds are still expected to become gusty this afternoon, but
gusts have been slow to materialize at KALB/KGFL where the
terrain is likely blocking some of the stronger southwest winds
from occurring. South to southwest gusts of 20-25 kt are still
possible this afternoon before winds diminish quickly after
sunset, becoming light southerly. Winds will become nearly calm
or light and variable late tonight before going south-southeast
at around 5 kt late Tuesday morning.

Outlook...

Tuesday Night: Moderate Operational Impact. Likely RA.
Wednesday: Moderate Operational Impact. Chance of SHRA...TSRA.
Wednesday Night: Moderate Operational Impact. Breezy Likely SHRA...TSRA.
Thursday: Moderate Operational Impact. Windy With Gusts To 36.0 NO SIG WX.
Thursday Night:  Slight Chance of SN.
Friday: Low Operational Impact. Slight Chance of SN.

&&

.HYDROLOGY...
Drier and much colder air over our region through
tonight. Then, dry weather continues through Tuesday but
temperatures are expected to warm today through Wednesday and
snow melt should occur into the middle of next week. The next
chance of widespread rainfall will be Tuesday night through
Wednesday.

The latest MMEFS shows minor rises in area rivers and streams
with the system Tuesday/Wednesday.

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...NAS/JVM
NEAR TERM...NAS
SHORT TERM...NAS/JVM
LONG TERM...Wasula
AVIATION...Thompson
HYDROLOGY...NAS/JVM



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