powderfreak
New member
Let me start by looking at what can go wrong: Wind flow is off ever so
slightly. A difference of a couple degrees of direction will make a big
difference. I'd like more cold air advection to mix in with the moist
flow from the Canadian Martimes. Besides those two things, I really can't
come up with much that can go wrong.
Vertically stacked cut-off low pressure system from the surface to 850mb
to 700mb to 500mb to 300mb means the deep low over the Canadian Martimes
is not moving anywhere soon. Once it absorbs the low pressure system that
is moving through the northern Mid-Atlantic and southern New England, it
will back ever so slightly bringing moisture into the north country of NY
and VT. Last chance for major model changes will be at 00z tonight and
that will be the time that it is obvious what effect the energy bringing
snow to NYC will do.
I feel very confident with a significant upslope snowfall event. One with
heavy snowfall and high winds bringing blizzard conditions to the higher
terrain of the Greens and Adirondacks from Friday evening through a chunk
of Saturday. This event will pulse, like its alive, as chunks of energy
and slight deviations in moisture/dynamics swing through. Upper level
300mb low is completely cut off from the jet stream and actually develops
its own jet streak that moves in from the NE. I don't know if I've ever
seen that before on the models. It would bring extremely favorable jet
dynamics that are usually not present for these events.
Since the atmosphere is vertically stacked, it also means the favorable NW
flow is coming in from all levels from the surface to the jet stream.
Again, not sure I've seen this situation before. Usually, we get a NW
flow to maybe 700mb but the jet stream is still blasting through west to
east. This set up is going to allow clouds to build, and build high.
Much like Lake Effect, you do not need high cloud growth to get good
precipitation rates, but it certainly does not hurt...same goes for
convection/thunderstorms, the higher the better. All atmospheric profiles
look good for strong lift through all levels bringing very steep lapse
rates.
This will likely come in waves, some hours heavier than others from Friday
afternoon through Saturday afternoon. Duration will not be an issue.
24hrs of favorable conditions appear likely. A shot of dynamics and
strong 500mb vort max moves through Friday afternoon. Still think a line
of squalls/heavier snow showers will move through the Champlain Valley,
Adirondacks, and Greens tomorrow evening. I like the NWS forecast of up
to 2" straight to the valley floors with this line by tomorrow evening.
Models bring in deeper moisture to 700mb and increase precipital water
from the NE, thank you Maritime air.
Then, Friday night is periods of heavy snow from the MRG/SB region
northward in the Green Mountains and across the northern Adirondacks.
Winds increase to 50-70mph at 5,000ft. Heavy snow and blowing snow with
cold temps will cause brutal conditions during Friday night above 2,000ft
along the spine and northern Adirondacks.
Winds will be a problem on Saturday...for lift operations especially. NW
winds of 40-60kts for most of the day on Saturday at 5,000ft and 30kt
gusts at the surface will make Saturday feel quite cold. But it will aid
in the transport of moisture up and over the spine throughout the day.
Snowfall will continue at varying intensities during Saturday. I haven't
looked into Lake Champlain enhancement into northern Addison county but
might need to be considered later.
I will throw out some rough guesses for snowfall right now, I do not like
to go high with forecasts at this time period away from an event.
However, I've never seen quite these dynamics for an upslope event so I'm
not exactly sure what to expect. Will follow model QPF relatively close
with changes made to my local knowledge.
By early afternoon on Saturday, a general 6-12" across Green
Mountain/northern Adirondack lower elevations (500-2,000ft) with up to 18"
above 2,000ft, especially the further north you go but generally with
these events, all bets are off. This might be conservative but is the
route to go until I can see it develop on Friday.
Here's a map of projected model QPF...these are liquid amounts and with the cold air, good snow growth with upslope events, fluff factor will be significant. Use 15 or 20 to 1 ratios and figure out what your favorite mountain might be looking at:
More to follow, possibly tonight, likely tomorrow.
-Scott
slightly. A difference of a couple degrees of direction will make a big
difference. I'd like more cold air advection to mix in with the moist
flow from the Canadian Martimes. Besides those two things, I really can't
come up with much that can go wrong.
Vertically stacked cut-off low pressure system from the surface to 850mb
to 700mb to 500mb to 300mb means the deep low over the Canadian Martimes
is not moving anywhere soon. Once it absorbs the low pressure system that
is moving through the northern Mid-Atlantic and southern New England, it
will back ever so slightly bringing moisture into the north country of NY
and VT. Last chance for major model changes will be at 00z tonight and
that will be the time that it is obvious what effect the energy bringing
snow to NYC will do.
I feel very confident with a significant upslope snowfall event. One with
heavy snowfall and high winds bringing blizzard conditions to the higher
terrain of the Greens and Adirondacks from Friday evening through a chunk
of Saturday. This event will pulse, like its alive, as chunks of energy
and slight deviations in moisture/dynamics swing through. Upper level
300mb low is completely cut off from the jet stream and actually develops
its own jet streak that moves in from the NE. I don't know if I've ever
seen that before on the models. It would bring extremely favorable jet
dynamics that are usually not present for these events.
Since the atmosphere is vertically stacked, it also means the favorable NW
flow is coming in from all levels from the surface to the jet stream.
Again, not sure I've seen this situation before. Usually, we get a NW
flow to maybe 700mb but the jet stream is still blasting through west to
east. This set up is going to allow clouds to build, and build high.
Much like Lake Effect, you do not need high cloud growth to get good
precipitation rates, but it certainly does not hurt...same goes for
convection/thunderstorms, the higher the better. All atmospheric profiles
look good for strong lift through all levels bringing very steep lapse
rates.
This will likely come in waves, some hours heavier than others from Friday
afternoon through Saturday afternoon. Duration will not be an issue.
24hrs of favorable conditions appear likely. A shot of dynamics and
strong 500mb vort max moves through Friday afternoon. Still think a line
of squalls/heavier snow showers will move through the Champlain Valley,
Adirondacks, and Greens tomorrow evening. I like the NWS forecast of up
to 2" straight to the valley floors with this line by tomorrow evening.
Models bring in deeper moisture to 700mb and increase precipital water
from the NE, thank you Maritime air.
Then, Friday night is periods of heavy snow from the MRG/SB region
northward in the Green Mountains and across the northern Adirondacks.
Winds increase to 50-70mph at 5,000ft. Heavy snow and blowing snow with
cold temps will cause brutal conditions during Friday night above 2,000ft
along the spine and northern Adirondacks.
Winds will be a problem on Saturday...for lift operations especially. NW
winds of 40-60kts for most of the day on Saturday at 5,000ft and 30kt
gusts at the surface will make Saturday feel quite cold. But it will aid
in the transport of moisture up and over the spine throughout the day.
Snowfall will continue at varying intensities during Saturday. I haven't
looked into Lake Champlain enhancement into northern Addison county but
might need to be considered later.
I will throw out some rough guesses for snowfall right now, I do not like
to go high with forecasts at this time period away from an event.
However, I've never seen quite these dynamics for an upslope event so I'm
not exactly sure what to expect. Will follow model QPF relatively close
with changes made to my local knowledge.
By early afternoon on Saturday, a general 6-12" across Green
Mountain/northern Adirondack lower elevations (500-2,000ft) with up to 18"
above 2,000ft, especially the further north you go but generally with
these events, all bets are off. This might be conservative but is the
route to go until I can see it develop on Friday.
Here's a map of projected model QPF...these are liquid amounts and with the cold air, good snow growth with upslope events, fluff factor will be significant. Use 15 or 20 to 1 ratios and figure out what your favorite mountain might be looking at:
More to follow, possibly tonight, likely tomorrow.
-Scott
