Winter Storm Update : 11:30am

“Captains Log : Round 742583.9… we’ve received word from the federation, that the snow may never end. They have advised us that because of the wintry anomaly, that reinforcements can not penetrate the snow shield. We are on our own, and will need to face the white winter threat alone…”
Joking aside, we know everyone is becoming weary of this weak and disorganized…. but stubborn and persistent storm. The radar clearly shows that the snow has redeveloped over the region, despite all appearances yesterday that this system was over. The snow is moving from SW to NE and redeveloping as it does.  Notice the radar fill in over eastern PA , and that is heading our way.
Radar Loop : 10:20am – 11:20am
So expect periods of on and off light to moderate snow, to continue through the afternoon hours. Guidance suggests the snow tapers from west to east slowly… beginning after 2pm, but possibly not tapering off completely until 8pm. So conditions are not likely to improve this afternoon. Temps are in the mid to upper 20s due to the snow… and could rise around 30° if the snow stops.
ADDITIONAL accumulation could be another coating to as much as 2 inches in some spots. That’s on top of what was on the ground as of 10am this morning. That should bring most locations to a final accumulation of 3 to 7 inches when all is said and done. Conditions should gradually improve overnight… but will be very cold, with lows falling into the teens.
Feel free to continue providing us with snow totals, observations and road conditions. Either in the comments below, or in the Observation thread from earlier this morning. Stay warm, and stay safe Hudson Valley. As Alex would say… “Keep calm…. and Weather On.” ???

2/18/21 Winter Storm Afternoon Update

The 1st stage of our storm is just about complete. However… we have about 3 or 4 more stages of this storm to push through. This weak and disorganized system is going to bring a lot of uncertainty with it. So lets break this system into pieces to discuss.

Stage 1 (2am – 2pm) :

The radar loop shows how the first area of moderate to heavy snow is pushing mostly southeast of our area. Areas south of I-84 did get in on some of the heavier snow, and we have seen reports of 1 to 3 inches of snow in parts of Rockland, Westchester, and Putnam counties. But the remainder of the region has anywhere from a dusting to an inch after Stage 1.  This is going to give the impression of a completely busted forecast.  The forecast of 3 to 7 inches is no where near being verified for 75% of the region, mainly anyone north of I-84.  This was not entirely unexpected… although guidance did originally suggest this batch of snow pushed a bit further north before moving out.

Stage 2 (2pm – 8pm)

This is the futurecast radar of the storm from 1pm to 8pm.  You can see the area of moderate snow pushing out to sea in the first frame at 1pm.  Then as we go through the next 2 or 3 hours, the guidance believes an area of light to moderate snow will fill in on radar across northeast PA and into the Hudson Valley.  This is due to considerable upward motion (vertical velocity) in the mid levels of the atmosphere.

The yellows and oranges indicate fairly good upward motion in the atmosphere, which could cause snow to develop and enhance, even though the radar looks quiet now.  If this is correct… despite the radar indicating that the snow is just about over… we should see the radar begin filling in, and spreading into the Hudson Valley through the afternoon hours.  For this reason, we anticipate periods of light to moderate snow through the afternoon, and into the early evening hours.  Accumulations over this time are likely to be a dusting to an inch or so… maybe an inch and a half in a few spots.

Stage 3 (8pm Thu – 8am Fri)

This futurecast simulation from 8pm tonight to 8am on Friday shows repeated periods of on and off light to moderate snow.  The lift in the atmosphere associated with the coastal low pressure appears to be enough to generate repeated areas of steady snow, that will accumulate slowly… but steadily through Thursday night and into Friday morning.  Here is the snowfall map associated with this 12 hour period of time…


This map is projected that for every 1 inch of liquid, we would see 10 inches of snow.  Actual snowfall ratios could be closer to 12 to 16 inches of snow for every 1 inch of liquid.  Here’s a visual representation of how the snow ratios could set up.


So the overnight snow amounts could be closer to 1.5 inches, possibly even 2 inches in the Hudson Valley.  A very minor difference… but could make a difference when compiled into the total storm.

Stage 4 (8am to 7pm Friday) :

You see that during the daylight hours on Friday (from 8am to 7pm), that the snow continues to fall around the Hudson Valley.  It may taper off at times, and fall steadily at others… but the snow is clearly in our region through the day on Friday, per the computer guidance.  Once again, these snowfall rates are not very impressive.  Here are the projected snowfall amounts from 8am to 7pm on Friday…

So once again… another 12 hour period of time, where another 1 to 2 inches of snow can fall.  These snow rates are not overly impressive, but the potential for an extended period of time, with persistent and consistent light to moderate snows.  This could add up over time… and by the time all is said and done, not counting what has fallen so far… here is the projected additional snow… after 1pm Thursday…

So in conclusion… when we eliminate the snow from this morning, that clipped the lower Hudson Valley and was focused south of the region… you can see that the guidance still believes that additional areas of persistent light to moderate snow will develop and fall in the Hudson Valley.  An additional 3 to 6 inches of snow is possible… mostly in the mid Hudson Valley.  The Catskills and upper HV may see slightly less snow… but even there, an additional 2 to 3 inches of snow is likely.

Could this be wrong?  Absolutely!  Any time there is a weak storm system, with an expectation that snow will develop right over top of us, and possibly continue for such an extended period of time… it’s entirely possible that the computer model is wrong about the development of light to moderate snow.  It is equally plausible, that the model does not show enough snow, that the upward motion that is expected is more significant… and the moderate snow becomes heavy at times.  These type of scenarios are very difficult to pinpoint… so we will trust that the model is properly projecting the atmospheric dynamics that will cause snow to develop and enhance over the Hudson Valley for the next 36 hours.

So in conclusion…. “No… this storm is not over.” … and at least for now, this storm is not a bust.  Be sure to anticipate a snowy, and slick Thursday afternoon and evening.  A snowy Thursday overnight… as well as a snowy Friday morning and afternoon, before things finally begin tapering off Friday night.  More updates as necessary.

Thursday Discussion : Final Snowfall Forecast Thu 2/18 – Fri 2/19

Hot on the heels of a Monday night storm that brought a wintry mix to the Hudson Valley, comes another snow threat.  A relatively weak system developing in the southeast, will push into the Mid-Atlantic on Thursday.  This will spread snow northeast, into the Hudson Valley.

Timing:
– 2am to 9am : Scattered Light snow showers possible
– 9am to 1pm : Steady snow develops from SW to NE
– 1pm to 6am Fri : Periods of light to moderate snow expected
– 6am to 3pm Fri : Periods of light snow, gradually tapering off

Impact/Conditions:
– Long duration snow event
– Periods of light to moderate snow
– Winds not an issue
– Temps in the 20s, snow accumulates on all surfaces
– Snow covered & icy roads likely

Snow Accumulations:
– Entire Hudson Valley Region : 3 to 7 inches (locally 8″+)

Additional Discussion to follow separately.

Wednesday Discussion : Preliminary Snowfall Forecast Thu 2/18/21

A weak storm system developing in the southeast will spread northeastward on Thursday.  As it does, it will likely spread snow into the Hudson Valley.  The details of how this event will unfold are a bit unclear, but hopefully will resolve themselves on Wednesday.  But for now, the potential exists for a moderate snowfall across the region.

Timing:
– 7am to 1pm : Light snow likely developing from SW to NE
– 1pm to 6pm : Snow becomes steadier and widespread
– 6pm to 6am Fri : Periods of snow expected
– 6am to 6pm Fri : Periods of light snow possible/likely

Impact/Conditions:
– Potential long duration snow event
– Periods of light to moderate snow
– Winds not an issue
– Temps in the 20s, snow accumulates on all surfaces
– Snow covered & icy roads likely

Snow Accumulations:
– Catskills & Upper HV (Zone 1,2,N3,N4) : 2 to 6 inches
– Mid & Lower Hudson Valley (Zone S3,S4,5-9) : 4 to 8 inches (locally up to 10″)

— Discussion —

A storm system developing in the southeast will move northeast early Thursday, into the Mid Atlantic states.  As it does, there are some questions about the manner in which the storm develops.  The storm track will follow the northern edge of the offshore ridge.  But how the energy consolidates is a bit less certain.  Here is a futurecast radar from 1am Thursday through 7am Friday, that shows a storm that looks a bit disorganized at times through its progression.

Futurecast Radar : 1am Thu – 1am Fri

The snow tries several times to push into the Hudson Valley on Thursday, before making a successful push northward late in the day on Thursday.  How exactly this storm progresses could have significant implications for accumulations in the Hudson Valley.  From the wide view perspective, it seems like 2 separate pieces of energy.  From the 500mb level, it looks like the energy gets stretched from Louisiana to eastern Maine.  This elongated look to the energy may give us an extended period of snow.

As a result, we’ll have to monitor the progression and development of the storm on Wednesday, before we issue the final snowfall forecast.  The potential for a long duration event, with an geographically extended system, leaves a lot of room for error in the preliminary forecast.  The probability our final forecast will differ from our preliminary forecast, is quite high.  If we had to list our confidence level on the accumulations, it would be Low to Moderate confidence.  There are a lot of ways the details could change on how this storm unfolds.  Please check back late on Wednesday afternoon, to see if we have any new data to share.  The “Final Snowfall Forecast” will be issued before 9pm on Wednesday.

Tuesday Discussion : Final Snowfall Forecast 2/9/21

In the midst of a very active wintry weather pattern, Mother Nature has the ability to throw curve balls and sneak up on you.  Tuesday is very likely one of those times.

Timing:
– 3am to 7am : Light to moderate snow develops
– 7am to 1pm : Snow… locally heavy at times
– 1pm to 4pm : Snow tapers off

Impact/Conditions:
– Light to moderate snow Tuesday morning
– Snow rates over 1″ per hour possible in some locations
– Very cold temperatures = Light fluffy, high ratio snow
– Snow covered and icy roads likely
– School delays/cancellations expected
– Light winds expected, minimal blowing and drifting
– Both AM and PM commutes significantly affected

Snow Accumulation:
– Upper HV & Northern Catskills (Northern half of Zone 1,2,3,4) : 2 to 6 inches
– Catskills & Mid Hudson Valley (Southern 1,2,3,4) : 4 to 8 inches
– Southern Catskills & Lower Hudson Valley (Zones 5,6,7,8) : 4 to 8 inches
– Extreme Lower HV (SW corner of 8 & Zone 9) : 2 to 6 inches

-DISCUSSION-

The snow starts before sunrise in most of the Hudson Valley, and continues until early or mid afternoon.  Snow could fall heavy at times around the Hudson Valley and Catskills.  Road conditions will become snow covered and icy, with temps holding in the low to mid 20s all day.  Travel will be quite hazardous.  The good news, is that winds won’t be much of a factor on Tuesday.  The area of heaviest snow with this system is rather narrow… and runs from just south of Albany, to just north of NYC.  Normally, we would have considerable hesitation with the snowfall forecast, but the computer guidance has been extraordinarily consistent with the position of the heaviest snows.  The Hudson Valley has been in the ‘bullseye’ on just about every run, of every computer model… for the last 36 hours.  So we feel very confident, that the heaviest snows with this small system… will be in our area.

The 4 to 8 inches is likely going to catch some people off guard, because other forecasts are calling for 2 to 4… or 3 to 5 inches of snow.  But allow us to make the case for the 4 to 8 inch snow forecast.  Temperatures on Tuesday will be very cold, temps in the Hudson Valley will be in the low to mid 20s during the snow event.

Forecast Temperatures at 10am Tuesday

In addition, the atmosphere is very cold.  When the 850mb (cloud level) temperatures are between -5°C and -8°C, that is the ideal range for snowflake production.  It will create a light and fluffy powdery snow flake, that does not compact when it reaches the ground

When conditions are this cold, we can get what is known as a ‘high ratio’ snow.  That means more ‘bang for your buck’ in terms of snow accumulations, given the same amount of moisture.  Under standard conditions, for every 1 inch of liquid moisture, you can get 10 inches of snow.  However, when the air is colder, the snow becomes more powdery, and fluffy in consistency.  This allows the snow to accumulate without compressing or packing down as it does.  The result, is you can get accumulation ratios that are 12″ of snow or 15″ of snow, for every 1″ of liquid.  Conditions on Tuesday, are likely to be roughly 15 inches of snow, for every 1 inch of liquid.

Now, it is a bit hard to tell from this map, because cities are not marked… but the Hudson Valley is roughly around 14 or 16 inches of snow, for every 1 inch of liquid moisture.  This will give us a fluffy powder, which will accumulate at a faster rate than a snow like was seen on Sunday.  So the next question is how much moisture is available for the Hudson Valley.  Here is the NAM model, which is roughly the average… and thus a good representative… of all the computer model data available.

This gets us anywhere from about .4 to .5 inches of liquid on average, across the Hudson Valley.  The areas of blue, represent locations where over half an inch of liquid is projected.  There will be pockets of heavier precipitation with heavier bands of snow that develop.  So if we take Poughkeepsie’s 0.48″ of liquid equivalent… and multiply that by the 15 to 1 snow ratio… that gives us 7.2 inches of snow in Poughkeepsie.  Areas that see 0.40″ of liquid, would see 6 inches of snow.  Even areas that see 0.35″ of liquid, would see 5.25 inches of snow.

On this map, any location in purple, is at least 6 inches of snow.  That is a rather large area of 6 inches of snow projected for most of Dutchess, Ulster, Sullivan, and even northern Orange county.  The 4″ line, extends all the way down to southern Orange County and northern Westchester County on this particular map.

For this reason… we feel fairly comfortable with a widespread 4 to 8 inches of snow for the center of the region.  The northern and southern most counties, could see a little less, and so the 2 to 6 inch range… which accounts for the slight “wobble” in the area of heaviest moisture.

We’ll see how it plays out…

Sunday 2/7/21 Snow Updates : 3pm Update

3:15pm Radar Discussion

Just as quickly as the snow moved in… it’s moving out of the northwest half of the region. You can see on radar that the back edge is sliding east southeast and that is shutting off the snow for places like Sullivan, Delaware, Greene, and western Ulster counties. We’ll watch as a band of snow pushes into the Catskills, but that is weakening and might give another coating to half inch in some spots… otherwise, the snow is over for our NW viewers, after many of them saw just a coating to an inch or so.
For those east of the Hudson, and those south of I-84… the snow will gradually taper off over the next 1 to 2 hours. South of I-84, and especially viewers in Rockland and Westchester counties, thats where the heaviest snow has fallen today. 2 to 5 inches of snow appear likely in those areas, as bands of heavy snow have pushed through those counties. Along the I-84 corridor however… places like Newburgh, Middletown, Poughkeepsie, New Paltz… a general 1 or 2 inches, maybe a spotty 3 inch total will have fallen when all is said and done.
You can see on this radar, that the bands of heaviest snow have been… and continue to be, in Connecticut, Long Island, NYC, as well as Central & Southern NJ. In those areas, 6″ of snow or more could have fallen. The storm track was just about 25 to 50 miles too far south and east, and the result is what we saw today. A system that just clipped the Hudson Valley.
Cold air surges in tonight, and overnight lows will be in the single digits and possibly near 0° in a few places. Watch for icy spots overnight tonight.

12pm Update

The computer guidance that suggested the heaviest snows were south and east of the Hudson Valley appear to have been correct. You can clearly see on this radar loop, that the deepest blues (indicating the heaviest snowfall rates)… are mainly south of the Hudson Valley.
Radar Loop : 10:50am – 11:50am
The exception being Rockland and Westchester counties, where on radar, it appears that snowfall rates over 1″ per hour are currently occurring. A band of heavy snow looks to run from New City to Tarrytown, up toward Pleasantville and Mount Kisco… even extending back toward Danbury. This was precisely why we held with the 2 to 5 inch forecast in this area, and its possible that we see some 6″ or 7″ totals if this band persists for an extended period. We’ll have to monitor this band, and see if it moves north in to Southern Orange County and Putnam County. But clearly, the worst conditions today will be south of I-84… and the closer you get to NYC, the better the odds you reach 6″ of snow.
 
The Mid Hudson Valley is seeing periods of light to moderate snow falling, but it’s clearly not as intense as what we’re seeing over the lower HV. On this hour radar loop, the snow bands are broken and lighter… even tapering off for a time for everyone from Port Jervis, to Middletown, Newburgh, up toward Poughkeepsie and Dover Plains. We should see this band fill in and intensify over the next 2 hours. Snowfall rates could climb as high as 1″ per hour for a time between 12pm and 3pm. It’s in this area, that final accumulations of 2 to 3 inches are most likely, as we’ll see a steady snow, but not nearly as heavy as snow rates further south.
 
The Upper Hudson Valley from Kingston to Saugerties and points north, is where periods of light snow could occasionally become a moderate snow. The moisture from the coastal storm will struggle to push further north, and so accumulations of a 1/2 inch to 2 inches are more likely.
 
Snow will continue for the next 2 to 4 hours on average… tapering off from west to east, as the back edge of snow pulls through. Road conditions will be snow covered and locally treacherous… and for viewers south of I-84, travel conditions could become very hazardous. Use the appropriate caution this afternoon.

Final Storm Forecast – Sunday 2/7/21

Well… this will be interesting, one way or another.  At this hour, 12 hours before the storm, we still have conflicting data.  So here’s the forecast, and lets talk briefly about it…

Timing :
– 7am to 11am : Snow begins from south to north
– 10am to 2pm : Steady snow, possibly heavy at times
– 2pm to 6pm : Snow tapers from west to east

Impacts :
– Quick system, fast mover, 6 to 8 hours in any location
– Snow rates around mid day could be up to 1″ per hour
– Cold, snow accumulates on all surfaces
– Considerable uncertainty regarding intensity and strength of system

Snowfall Forecast:
– Lower Hudson Valley : 2 to 5 inches
– Remainder of Hudson Valley : 1 to 3 inches

*Notes : Low confidence forecast.

— Discussion —

An extremely irritating storm to forecast, due to the wild swings in the computer model data, taking us for a ride that’s as nauseating as the worst rollercoaster you can imagine.  Six days ago this was projected to be a major snowstorm, almost as big as the storm from Monday.  That got everyone’s attention, and then the storm faded into the computer model abyss by mid week.  So we spent a day or two explaining to everyone that the major snowstorm that social media was buzzing about, was all but surely not going to happen.  Then slowly over 24 hours, computer guidance visited the local “lost and found” and located the storm once again… bringing it back along the east coast.  The new version of the storm looked to be able to drop 3 to 6, possibly 4 to 8 inches of snow.  Then, no sooner do we post the ‘preliminary forecast’… then the models begin shifting the storm further offshore.  This threatens to turn the storm back into a 1 to 3 inch event.

That brings us to our current snowfall forecast.  Due to limited moisture, and a fast moving system, snowfall totals of 2 to 3 inches seem likely, with possibly only an inch or two in the northern Hudson Valley.

This solution is the result of slightly less energy in the southern branch jet stream.  The storm is a little weaker as a result, a little further off shore, and has a little less moisture.  This is what we’ve seen trend on most of the guidance over the past 24 hours… a weaker, lower impact storm.  A general 1 to 3 inches, possibly 4 inches in a few spots.  As a result, we lowered our forecast for Sunday.

But we could see a scenario where this system has just a bit more energy in the southern jet… as the storm begins to develop, a little extra convective energy could transition to a stronger, more amplified jet stream.  This would bring the storm an additional 25 to 50 miles closer to the coast.  This would also deepen the storm quicker, providing more moisture to the Hudson Valley.  The end result… would look like this…

Both of these solutions shown here… are from computer model data that has come out in the last 6 hours (as of this post).  The NAM image shown here, is the extreme solution.  This is what would happen if everything comes together at the last second.  Instead of widespread 1 to 3 inches, it would be widespread 3 to 5 inches, with some localized totals of 6″ possible.  It’s also possible that we see a less intense version of the NAM, with slightly lower moisture amounts.  It really is a ‘nowcasting’ situation.  Nowcasting is when we stop looking at just computer model data, and start comparing prior computer data, to actual conditions… to see if the computer models are ‘verifying’.  If the computer models we based the forecast on turn out to be correct when compared to actual conditions… then we know we have the right idea.  But if we compare the computer model from 12 hours ago, and see that the actual conditions are noticeably different… then we know the models are either overstating, or underestimating the storm.  Then we can adapt, and pass the new information to you.  It can help you better temper your expectations for how the storm is going to unfold… even if you get the information only a few hours before it happens.  Information is power… and in this case, power could help keep you safe.  So we’ll see how it plays out.

We’ll be posting on Facebook on Sunday, and unlike the previous storm, we will be posting the updates here as well.  That was something we failed to do during the previous storm, and apologize for anyone who does not use Facebook.  We really feel like the general 2 to 3 inch amounts, with a localized 4″ total… are the most likely result on Sunday.  But lets see how it turns out.  Stay safe… and enjoy the light to moderate snow event on Sunday.

Preliminary Snow Forecast : Sunday 2/7/21

Seemingly hot on the heels of our storm 5 days ago… we’re tracking another storm for Sunday.  This storm is a particularly difficult system to forecast, as it is developing as it approaches the east coast.  The atmosphere dynamics trying to steer it up the coast are not very strong, so there is considerable uncertainty with the details of the forecast.

Timing :
– 5am to 9am : Snow begins from south to north
– 9am to 2pm : Steady snow, possibly heavy at times
– 2pm to 6pm : Snow tapers from west to east

Impacts :
– Quick system, fast mover, 6 to 8 hours in any location
– Snow rates around mid day could be up to 1″ per hour
– Cold, snow accumulates on all surfaces
– Considerable uncertainty regarding intensity and strength of system

Snowfall Forecast:
– Entire Hudson Valley : 2 to 6 inches

*Notes : likely to get a better handle on track and strength of system on Saturday, we may have to adjust snow totals up or down just a bit for final forecast Saturday PM

Discussion

This storm system at first look 5 or 6 days ago, was projected to be a major snowstorm for the region.  Then early/mid week… the models lost it entirely, sending it harmlessly out to sea.  Then 48 hours ago, the models detected a bit more energy in the southern jet, and this system has come back into play for the weekend.  The big question however, is just how strong is that southern branch energy?
– Is it going to help the system deepen quickly, and track right along the coast? … or…
– Is the energy flatter, keeping the system weaker and further off shore?

If the answer is the first… we could have a potent little storm system in the Hudson Valley.  One capable of dropping snowfall rates of 1″ per hour for several hours in the middle of the day.  The stronger storm would track closer to the coast and then out to sea by sunset.  By the time it tapers off… the snowfall in the northeast could look like this:

Stronger Solution : Closer to the coast = higher snowfall amounts

However, the computer guidance has been fluctuating from a stronger solution, to a weaker solution, as the models try to get a handle on the energy in the southern branch of the jet stream.  The difference in the atmospheric energy is small, but the end results are noticeable.  The slightly weaker solution means the low pressure doesn’t deepen as much.  If the storm doesn’t deepen as much, it won’t be pulled as far up the coast.  If it doesn’t come as close to the coast, the precipitation amounts in the Hudson Valley will be less… and as a result, snowfall totals will be less.

Weaker Solution : Further from the coast = lower snow totals

Unfortunately, we’ve seen next to no consistency in the guidance.  It’s been like a roller coaster, going up, then down… then back up… then down again.  The very latest guidance, is the image you see above.  The system is weaker, and pulls out to sea faster.  As a result, the northern edge of the snow is stunted, and begins to push east as it gets over the Hudson Valley.  Areas south of I-84 would see 3 to 5 inches, and the rest of us would likely see 2 to 4 inches roughly.

Does this mean we’ll only see 2 or 3 inches?  Possibly.  But we always look for the trend when forecasting, and right now we’re not seeing one.  That should change on Saturday, as the energy comes out of the Rockies, and dives into the Tennessee Valley.  So for that reason, we should be able to post our Final Snowfall Forecast by early evening on Saturday (roughly 12 hours before the start).  If the trend for a weaker storm continues, expect a downward adjustment in the snow totals.

We’ll see what the data holds on Saturday.

Final Snowfall Forecast : Monday 2/1 – Tuesday 2/2

Winter Storm Warnings are beginning to be issued across the southern Hudson Valley, and soon to be followed across the remainder of the Hudson Valley, as we track an evolving complex storm system that is now likely to be a major event for our region.

Timing :
– 9pm Sun – 2am : Light snow develops over southern half of HV
– 6am to 10am : Moderate snow develops from south to north
– 10am to 6pm : Moderate to Heavy snow
– 6pm Mon to 12am Tue : Light to moderate snow
– 12am to 6pm Tue : Periods of light to moderate snow tapers

Impacts/Conditions:
– Long Duration event expected, snow could last over 24 hours
– Monday AM commute likely impacted, especially from I-84 on south
– Accumulating snow may be delayed until morning in northern half of HV
– Heaviest snow likely late Monday morning through Monday evening
– NE winds 10 to 20mph, gusts over 30mph, blowing & drifting snow
– White out / Blizzard conditions possible at times
– Extremely difficult/dangerous travel Monday PM – Tuesday AM

Snow Accumulations:
– Eastern Catskills (Zone 2) : 18 to 24 inches (locally up to 30″)
– Majority of Hudson Valley : 12 to 20 inches (locally up to 24″)
* Red Circles = Downsloping dry air, potential lower amounts of 8″ to 14″
** Banding across mid/lower HV could result in localized reports up to 24″

— HVW Discussion —

No major changes to the basic structure and concept behind how this storm develops and impacts the Hudson Valley.  The primary changes, are in the amount of available moisture for our region.  Computer guidance is now consistently depicting 25% to 50% more moisture than at the time we created the preliminary forecast.  The result would be snow bands of 1 to 3 inches per hour during the day on Monday, combined with NE winds gusting over 30mph at times.  The stage is set for absolutely horrendous travel conditions Monday afternoon through Tuesday morning.

Futurecast Radar : 6pm Sunday – 6am Tuesday

This 36 hour radar loop shows that the potential exists for light snows overnight Sunday night in many portions of the Hudson Valley (lower half especially).  The start time of this event is going to vary greatly by location.  Some guidance has the snow starting by 8pm tonight south of I-84, other guidance waits until after midnight.  Some guidance delays start times for the northern half of the HV until near sunrise on Monday, other guidance says it’s snowing before midnight.  The problem, is dry air.  How strong and persistent is the dry air?  We’ll see.  But keep in mind that conditions could deteriorate before sunrise on Monday.

We’ll see an increasing band of heavy snow pushing northward Monday morning into Monday afternoon.  The heaviest snow is likely from late morning through early evening Monday, before the storm literally begins to ‘snow itself out’ Monday night.  The low pressure will sit and spin off shore the entire time, which means there are unanswered questions about how much (if any) snow continues to fall as we push into Tuesday around the region.  Notice by the end of the loop that the heavier snow pushes north of our area, but light snow showers are projected to continue falling.

When all is said and done, we feel the HRRR solution paints a very possible solution of snowfall across the region.

The position of the heaviest snow bands will be the determinant of who sees upwards of 20″ from this storm.  Much guidance says that the Hudson Valley will be where that occurs, but we can’t be certain.  The result is our wide range for a general 12 to 20 inches of snow.  We have concerns about moisture availability in some areas… especially the downslope locations circled in the snowfall forecast map.  In those areas, downsloping may dry the air enough to reduce snowfall amounts by up to 6 inches compared to areas surrounding them.  So a few locations may struggle to meet the snowfall forecast range.

In addition, some locations will see heavier bands of snow than others.  This will give the potential for some places to eclipse 20″ of snow.  Another factor in the wide snowfall forecast range.

Winds will also be an issue….
Futurecast Winds:  1am Monday – 1am Tuesday

Gusts out of the northeast between 25 and 40mph, will create blizzard conditions across the entire region, especially the higher terrain.  Areas in the Catskills could see gusts up to 50mph.  This will blow and drift the snow over 2 or 3 feet in some areas, creating possible white out conditions at times, and making travel virtually impossible late on Monday.  The snow is going to be a rather fluffy powder, and will not stick to trees and powerlines.  So our hope is that power outages will be minimal.  But anytime you have gusts over 35mph, the risk of outages will exist.

We will continue to update things over the next 36 hours, as we track a major winter storm for the Hudson Valley.

Preliminary Snowfall Forecast : Monday 2/1 – Tuesday 2/2

Winter Storm Watches are in effect for the entire Hudson Valley, as we track a complex storm system that is likely to bring a long duration snow event to our region.

Timing :
– 9pm Sun – 6am Mon : Light snow develops south to north (especially I-84 on south)
– 6am to 10am Mon : Moderate snow develops from south to north
– 10am to 6pm Mon : Moderate to Heavy snow possible
– 6pm Mon to 12pm Tue : Light to moderate snow possible
– 12pm to 6pm Tue : Snow tapers off from west to east

Impacts/Conditions:
– Long Duration event expected, snow could last for 24 to 36 hours
– Start time delayed by dry air in northern half of Hudson Valley
– Monday AM commute could be impacted, especially I-84 on south
– Heaviest snow likely late Monday morning through Monday evening
– NE winds 10 to 20mph, gusts over 30mph, blowing & drifting snow
– White out / Blizzard conditions possible at times
– Extremely difficult/dangerous travel Monday PM – Tuesday AM

Snow Accumulations:
– Eastern Catskills (Zone 2) : 8 to 16 inches
– Western Catskills, Upper Hudson Valley (Zone 1, N3, N4) : 5 to 10 inches
– Lower Catskills, Mid Hudson Valley (Zone S3, S4, 5, 6, 7) : 6 to 12 inches
– Lower Hudson Valley (Zone 8&9) : 8 to 16 inches

HVW Discussion

Low pressure from the Midwest will weaken as it moves into the Ohio Valley, and a secondary low pressure will develop off the coast of Virginia.  That coastal storm will intensify and move northeast, spreading snow from the Mid Atlantic states, through the Hudson Valley, and into New England.  The cold air, storm track, and intensity will all combine for a challenging forecast for the Hudson Valley.  All in all, it’s likely to bring a long duration snow event to the region.

Futurecast Radar : 1pm Sunday – 6am Monday

Dry air pushing south from New England will delay the northern progress of the snow band.  Above is the futurecast radar from 6pm Sunday to 6am Monday, and the snow moves into the low half of the Hudson Valley before midnight, but struggles to move north from there.  If this scenario is correct, 1 to 3 inches of snow would be possible in the mid and lower Hudson Valley by Monday morning.  But there is considerable uncertainty due to the dry air, so the start times may be updated on Sunday.

The low pressure over the Ohio Valley will weaken, and transfer its energy to the coastal low pressure.  It’s at that point, that the snow band is likely to intensify to our south… and begin pushing northward, into the Hudson Valley.

Futurecast Radar : 6am to 6pm Monday

The initial wave that pushes northward between late morning and early afternoon is likely to see rates of snow over 1″ per hour.  The big question is what happens after that.  The coastal low pressure will spin off shore, and how close to the coast it is will determine where the position of the heaviest snow bands are.  The counter clockwise rotation will spin snow bands northwestward, into the Hudson Valley.  The snow bands will begin to pivot as the low pressure slowly drifts eastward.  But the low pressure will not move away until early morning Wednesday, so the position of the heavy snow band as it stalls out, could mean the difference between 6 to 8 inches… and 12 to 18 inches of snow.  There is a high degree of difficulty with this forecast, because of these details.  Any time a storm stalls off shore, there will be a high bust potential to any forecast.  So we’ll have to be prepared to make changes or tweaks… and provide updates of new information, should things change as the storm begins to unfold.  Make sure to monitor the storm for updates.

Additional Details / Forecast Uncertainties

Strong NE winds will howl at 10 to 20mph, and gust over 30mph at times.

Projected Wind Gusts 1am Monday – 1am Tuesday

These wind gusts could combine to create blizzard and white out conditions around the region at the height of this storm.  Moderate, to at times heavy, snowfall rates combined with gusts over 35mph at times will make for treacherous travel conditions… Monday afternoon through Tuesday morning.  We’ll need to track the wind potential… because if these wind gusts are accurate, parts of the region could see blizzard warnings issued.  Snow drifts well over 1 or 2 feet are possible due to the blowing and drifting of snow… in addition to near zero visibility at times.

Northern parts of the region could experience lower snowfall amounts due to the combination of dry air, and downsloping winds.  The gusts shown above will be coming from the northeast.  Those direction winds create downslope winds on the west side of the Birkshires and Catskills.  That is in part why we have the lower totals in the northern Hudson Valley, as well as western Catskills.  With the moisture coming from the southeast, and northeast winds, the sinking air could lower totals in those areas… another factor that could cause forecast headaches.

Finally, how long this storm lingers, and the snow band pivots around the back side of the storm, really is a wildcard with regard to final snow totals and snow end times.

Futurecast Radar : Entire Event 7pm Sunday – 1am Wednesday

This radar loop is over 48 hours long, and snow is falling in portions of the Hudson Valley for much of that time.  This simulation suggests accumulating snows through at least 12pm on Tuesday, which would be over 24 hours in many places.  Where the back edge snow band stalls and pivots, and just how long the snow lingers, depend on the position and speed of the nor’easter.  There is a high probability that data changes in some capacity, which could have sizeable impacts on the forecast.  So the best way to summarize it is…

  • High confidence that the lower half of the Hudson Valley will have the highest snow totals
  • High confidence snow falls most of Monday
  • Medium/High confidence of a snowfall over 6 inches for everyone
  • Medium/Low confidence on snowfall forecast range (could be higher in mid Hudson Valley)
  • Medium/Low confidence on snow end times
  • Medium/Low confidence on axis of heaviest snow (where over 12″ are expected)

Hopefully this helps clarify where we stand with the forecast at this time.  We will monitor this storm up until, and through the entire event.  Please check here and on the Facebook page for updates.  Our final forecast will be issued Sunday afternoon.