Area Forecast Discussion


756 
FXUS61 KALY 110905
AFDALY
Area Forecast Discussion
National Weather Service Albany NY
405 AM EST Mon Dec 11 2017
.SYNOPSIS...
As lake effect dissipates today, we await our next winter 
weather event. Snow will overspread most of the region overnight
Monday and continue through Tuesday. Some warmer air may allow 
for snow to mix with rain from Albany and points southward 
through the Hudson River Valley. Brisk and colder weather is 
expected for the middle of the week in the wake of this storm. 
&&
.NEAR TERM /UNTIL NOON TODAY/...
As of 345 AM EST...Winter Weather Advisory for lake effect snow
remains in effect til about sunrise for northern Herkimer and 
western Hamilton counties. 
Lake effect plume off Ontario is finally showing signs of
dissipating as combinations of departing upper trough, lowering
inversion heights, and low level trajectories becoming more 
northerly. Otherwise, some flurries across the terrain will also
dissipate as cloud break for sunshine for a tranquil start to
the work and school week. As partial snow cover and low sun
angle, we will favor a blended approach of the guidance at this
time.  
&&
.SHORT TERM /NOON TODAY THROUGH 6 PM TUESDAY/...
...Winter Storm Watch continues for the Dacks, Lake George
Saratoga Region into southern Vermont...
...Winter Weather Advisory has been issued for the Berkshires... 
Breaks of sunshine will become filtered with additional higher
and mid level clouds later in the afternoon into the evening
hours. H2O vapor loop shows rather impressive and compact wave
crossing across the Dakotas into Minnesota. This Alberta Clipper 
will initiate surface cyclogenesis across the lower Great Lakes
and result with impressive isentropic lift across the northeast
corridor overnight into Tuesday. As stated in the previous AFD,
snow is expected across the entire region Tuesday morning as
surface low deepens to around 990mb Tuesday afternoon. 
Difference this run is the attempt for some warmer air to advect
into the mid levels from Albany and points southward through 
the Hudson River Valley for some rain/snow mixture. While this 
will cut down on overall accumulations, any slight deviations to
the thermal profiles will influence the snow accumulations. Per
extensive collaboration with neighboring offices and WPC 
guidance, we will continue with the winter storm watch for those
areas already highlighted, and issue a winter weather advisory 
for the Berks. Additional expansion of the advisory is expected
later today. Overnight lows in the 20s and highs Tuesday climb 
into the 30s for most of the region with near 30F for the Dacks.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
An active and wintry pattern will continue into next work week 
as a longwave trough persists over the eastern CONUS. While we 
will be monitoring numerous shortwaves rotating into the 
Northeast which will present a number of snow threats, model 
agreement remains poor on exact timing, placement and intensity 
of each shortwave. However, we have higher confidence in a 
period of below normal temperatures impacting eastern NY/western
New England Wednesday - Friday.
Tuesday night, the surface low and associated snowfall will be 
lifting into New England as cold air quickly filters into the 
region. A dry slot, evident in the model RH fields, will nose 
northward across eastern New York/western New England behind the 
surface low. This will help cut off the snowfall during the 
overnight period, with some snow showers lingering in the 
Adirondacks. 
During the day on Wednesday, the closed upper low will pass through 
the area, with some light snow showers possible. On the back side of 
this system, cold air flowing over the relatively warm lakes could 
lead to continued lake effect snow, especially in the Adirondacks 
and Mohawk Valley. Northwest flow will also lead to cold air 
advection and the start of cold temperatures in our region. H850 
isotherms fall to -15C to -20C throughout the day with little to no 
rise in afternoon temperatures. Blustery winds will also set in 
during the day with gusts of 30-40 mph possible, especially in the 
high terrain locations. These below normal temperatures, along with 
northwest flow, will lead to temperatures dropping towards 0 degrees 
in the Adirondacks to teens elsewhere Wednesday night. Wind chills 
overnight could fall into the negative teens in the Adirondacks 
overnight so we'll be keeping a close eye if any wind chill advisory 
headlines will be needed.
High pressure tries to nose in from Canada during the day Thursday 
and the change in flow regime plus subsidence should suppress the 
lake effect snow bands. Outside of lake effect snow chances, 
locations should stay dry.
Chilly temperatures remain in placement Thursday - Friday with high 
temperatures likely only rising into the upper teens to upper 20s 
and lows in the teens/single digits which is about 10 - 15 degrees 
below normal for mid-December. Our next shortwave exits the Great 
Lakes and heads into our area bringing the next threat for snow 
Friday - Saturday. While some moisture is associated with this 
disturbance, poor model agreement remains on placement, timing and 
intensity giving us a low confidence forecast on snow potential. 
Rising heights are possible in the wake of this upper disturbance 
leading to the flow regime shifting to W or even SW with 
temperatures rebounding closer to normal heading into the weekend. 
However, additional shortwaves are expected to traverse the 
Northeast late in the weekend into early next week which will once 
again bring additional threats for snow. 
&&
.AVIATION /09Z MONDAY THROUGH FRIDAY/...
VFR conditions are expected the remainder of the overnight and 
into the day on Monday. With an upper level trough overhead and 
lake-effect snow upstream of the area, there will continue to 
bkn-ovc cigs around 4-9 kft, esp for KGFL/KALB. Otherwise, 
light and variable winds or s-sw winds of around 5 kts is 
expected through the overnight hours with no precipitation
expected.
Daylight hours on Monday, there will be sct-bkn cigs around 4-6
kft with no precip through the day. Westerly winds will be 
around 10 kts. Some mid level clouds may increase towards 
evening as the next storm system approaches from the west.
Chance of snow appears to be after this TAF forecast cycle.
Outlook...
Monday Night: High Operational Impact. Definite SN.
Tuesday: High Operational Impact. Definite SN.
Tuesday Night: Low Operational Impact. Slight Chance of SHSN.
Wednesday: Moderate Operational Impact. Breezy Chance of SHSN.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: No Operational Impact. NO SIG WX.
Thursday Night: Low Operational Impact. Slight Chance of SHSN.
Friday: Moderate Operational Impact. Chance of SHSN.
&&
.HYDROLOGY...
No hydrologic problems are expected through the week ahead.
Cold weather with periods of snow and snow showers are forecast.
Ice will form and thicken on area lakes and rivers and some 
river gauges may start to show erroneous readings due to ice by 
the end of the week.
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...Winter Storm Watch from late tonight through late Tuesday 
     night for NYZ032-033-038-039-041>043-050-082>084.
     Winter Weather Advisory until 7 AM EST this morning for NYZ032-
     033.
MA...Winter Weather Advisory from 1 AM Tuesday to 1 AM EST 
     Wednesday for MAZ001-025.
VT...Winter Storm Watch from late tonight through late Tuesday 
     night for VTZ013>015.
&&
$$
SYNOPSIS...BGM
NEAR TERM...BGM/OKeefe
SHORT TERM...BGM/OKeefe
LONG TERM...JVM/Speciale
AVIATION...Frugis/BGM
HYDROLOGY...BGM/OKeefe
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