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Major Winter Storm Recap: Wednesday 3/7/18

In the span of just 5 days, the Hudson Valley was punished by 2 major nor’easters. In their wake, these storms have left us with…
– nearly 3 feet of snow in some places…
– thousands of people without power in other places…
– and all of us with a reminder of what winter storms in the Hudson Valley can be like.

So lets take a look at the recap.  We’ll start with the map review of our “Final Snowstorm Forecast” that was issued before the storm began (not the adjusted forecast map that we put out after realizing the storm was going to take a different track).  Next is the “Snow History Map” which shows what actually fell based on a combination of reports and radar data.  Finally will be the National Weather Service Snowfall Totals, which are reported in by NWS trained spotters.

So… before we get out our mental snow shovels and begin to dig into this, in general… if we take the entire Hudson Valley together, we didn’t do too bad.  The southeastern 75% of the Hudson Valley saw 12 to 18 inches of snow on average (or more in some cases).  The northwestern 25% of the region got shorted on snowfall amounts… and we’ll discuss why in a moment.

The Big Winners

So when you look at the map, there is a broken red stripe that runs diagonally from SW to NE across the Hudson Valley.  SE Orange, NW Rockland, bits of Putnam, northern Dutchess and much of Columbia counties… all got crushed by this storm.  Monroe with 27″, Sloatsburg with 26″, Highland Mills with 24″, Hillsdale with 24″, Chatham with 23″, Orange Lake with 20″, Mahopac with 19″… all of those locations, as well as others, were under that little stripe.

The reason those areas hit the snowfall jackpot, has to do with a feature we spoke about numerous times during the forecasting phase of the storm… snowfall banding.  There was a deformation band of snow that set up on the northwest side of this storm… affectively the boundary between the moist flow of air off the ocean, and the cold, dry air on the back side of the system.  This intense band of snow formed over the SE half of the Hudson Valley during mid afternoon, and then slowly pivoted overtop of them.  Resulting in an extended, multi-hour period of snowfall rates at 2 to 3 inches per hour!

Just look at this band of snow… even as of 6:15pm!  When you start to examine where the snow totals were off the scales… it’s no secret as to why areaas like Monroe got 26 inches of snow.  This band hammered them for hours.

The Rip Off Zone

The same image above that highlights the jackpot zone, can tell you exactly where the “rip off zone” is.  The Catskills were spared the heaviest snow totals from this storm.  After initially being projected to see 18″ to 24″ of snow in our final forecast… the storm played a dirty trick on us at the last minute, which we’ll go into momentarily.  But early Wednesday morning, we realized that some big changes needed to be made in our forecast… and by 10am on Wednesday, we released a “now-cast” adjustment to our forecast… and lowered the forecast to 5 to 10 inches across the western HV.

We realized that the storm was going to take a track that would simply rob the western Hudson Valley and Catskills of the moisture we were expecting to inundate those areas.  Sometimes with these dynamic winter storms, it’s not until the storm is just beginning, that you realize a change to the forecast is necessary.  We always talk about “now-casting” during storms, and this is why it’s so vital.  “Now-casting” is the process of using observations, radar data, and actual conditions… to analyze, modify or strengthen your forecast, to provide accurate information to your viewing audience.  As a forecaster, you need to be able to analyze the data in real time, and understand whether an adjustment needs to be made… so that people have the best information possible.

That was what happened in this case.  We received information in real time, that this storm was not developing where it was expected to… and we had to make significant changes on the fly.  Adjusting a forecast from 18 to 24 inches… down to 5 to 10 inches… is a pretty massive change.  When the snow dust settled, the forecast adjustment turned out to be a good one.  Kiamesha & Glen Spey had 12″, Greenville Center 11″, Monticello & Catskill and Phoenicia had 8″… and the area in general was 6 to 12 inches at the end of the storm.

What Happened?…
“Mother Nature is the Boss, that’s what happened.”

So the next part is the fascinating part from a meteorological standpoint.  In short… the guidance was wrong.  It failed to get a good hold on where the center of low pressure was going to develop.  Let’s first take a look at the consensus guidance leading up to the storm…

Guidance had the perfect track for the Hudson Valley, with a rapidly deepening storm hugging the coast until north/central NJ, and then tracking it just south of Long Island, before heading NE toward Cape Cod.  That kind of track will cause a change over to rain in NYC and Long Island, and even into the extreme lower Hudson Valley.  But this kind of track focuses the heaviest band of snow right over the Hudson Valley… pushing a substantial amount of moisture into the HV, and then the storm pivots east, holding the heavy snow in place for many hours.  This track was primed to deposit a widespread 12 to 18 inches of snow in the Hudson Valley, and even more in the Catskills.

However, early on Wednesday morning, we saw indications that the center of low pressure was going to take a significantly different track than what guidance had suggested.  We raced to make changes to our forecast, and when all was said and done, here’s the track that the storm ACTUALLY took

Rather than track up to north/central NJ, near Asbury Park… instead, it stalled it’s northward progression around Atlantic City… before making the turn NE.  This was roughly 50 to 75 miles further south than guidance suggested.  That meant a shift of roughly 50 to 75 miles southeast in the position of heaviest snowfall.  Now, as it turns out… the eastern 2/3 of the HV still got to the forecasted amount… but that was courtesy of the deformation band that stalled out over the eastern HV, providing several hours of 2 to 3 inch per hour snowfall rates.  Anyone who was northwest of that snow band… saw substantially less snow.

The Catskills and western Hudson Valley on average saw 6 to 12 inches of snow.  That’s still a significant snowstorm by almost any standard.  But when you realize that the Catskills would have gotten 18 to 24 inches of snow, if the storm had tracked as guidance suggested… it’s a major change.  If you look at the two maps, the track the storm actually took was drastically different than what was projected just hours before the event.

This is why we always harp on the storm track being so critical.  If the track is further east or west than expected, it’s going to change the end position of the heaviest snow band… and if you live in the area being forecast… it could result in major increases or decreases to your snowfall amount the end of the day.
But it’s also why we can never be ‘certain’ about snowfall totals in a snowfall forecast.  There was no way to see this coming.  There was no data, no guidance that suggested that this storm would track 50 to 75 miles further south and east than expected.  By the time the storm was off the coast of New England, the storm was 100 to 200 miles further east than projected.  These changes happened in real time, as the storm was beginning, and all we can do is make the assessment, and modify the forecast as quickly and effectively… so you have the best information.

From a forecast perspective… we lucked out.  Because the storm still had a strong enough band of heavy snow push into the forecast area of the Hudson Valley.  It provided the 3 to 4 hours of 2 to 3 inches per hour, to get most of the viewing audience close to… or within the forecast range, to where the storm forecast was considered a success.  (Even if we had several people on Facebook yelling about how it was not snowing and the forecast was a bust… despite the fact that we told everyone the snow would not get heavy until the afternoon on Wednesday).  But our viewers in the Catskills certainly would have noticed a difference between the forecasted amounts… and what actually fell.  But hopefully, you at least understand why.

Thank you to everyone who helped us gather data through this storm.  You’re ALWAYS a tremendous help in now-casting any event.  The HVW community provides us with an endless stream of information, that gives us an advantage in forecasting any storm.  You guys are the BEST!  And now… on to the next one, as this recap was delayed because we’re trying to hammer out what will happen with the next nor’easter.  But that’s another conversation…  Thanks for the support!

Sunday Outlook : Coastal Concerns

After 2 major nor’easters inside of a week, the worries about the coming storm for Monday night and into Tuesday started very early.  We downplayed the storm initially, because the storm wasn’t looking like a major threat… with the storm appearing suppressed out to sea on most of the guidance.  We stressed that while only about a 25% chance at the time… these things need to be monitored closely, because it was roughly 5 days away at the time.  Well… in the weather forecasting world… there’s sort of an unofficial saying with regards to these kind of systems, and that is “they always trend north”.  Well, that cliché has held true once more… and we need to talk about the likelihood of some snow on Monday night and Tuesday.

Now… first off, the period of concern has shifted, from Monday… to Monday night and Tuesday.  That’s because this system is projected to slow down a bit, and that slowing is also going to give room for the storm to turn north.

You can see that the storm is now projecting to develop much closer to the coast than what we were seeing just a day or two ago.  That’s likely because the storm is moving slower, so rather than be pushed out to sea by the northern jet stream… it’s allowing it to be captured, and pulled up the coast.

If the above image is accurate, it would begin snowing somewhere between 9pm and midnight most likely… but details will change as we get more information on this.  The snow looks like a general light to moderate snowfall… with the heaviest snowfall focused east of the Hudson Valley.  Still, at dark, with temperatures around freezing… snow could accumulate on all surfaces, even if it melts on roads initially.

By sunrise on Tuesday, the storm would still be impacting the Hudson Valley, with a widespread light to moderate snowfall.  Again, the heaviest snow rates would be as you go further east… so those of us east of the Hudson River would be likely to see the ugliest Tuesday morning commute based on our current information.  This scenario would allow for snow to continue falling through the morning, likely tapering around mid day on Tuesday.

By the time all is said and done, and the snow pushes to our east Tuesday afternoon… this is the simulated snow map…

We show you this map, just to highlight how much this storm is focused to our east… and that while we could be impacted… the worst conditions are certainly projected into New England.  This is NOT set in stone however, and we’ll need to watch closely to see if the storm tracks further west.

KEEP IN MIND… that our last nor’easter on Wednesday of this past week, shifted it’s track on us just as the storm was starting.  The Snowfall Recap will come out later today, and show that with no warning… we saw a large shift in the storm track… that had major implications for our snowfall forecast.  So there is PLENTY of time for this storm to shift it’s track further.  We need to watch this very closely… and we’ll have updates later today, on whether we’re seeing further changes.

Have a great day!

Saturday Outlook : Late Winter Chill

After a Friday night that featured some widespread snow showers and snow squalls… things should quiet down a bit for our Saturday.  Sure, consider us biased… but there’s just something about a harmless snow squall with half dollar sized snow flakes falling and melting harmlessly on the pavement on a seasonably chilly early March evening.  Looking up into the street light to see hundreds of flakes swirling to the ground, or night time driving in the snow… and throwing the high beams on, to make it look like you’re flying the Millennium Falcon in a Star Wars movie at light speed.  Something about the snow that just brings out the big kid in us.

Perhaps that’s why some people get so sour about a ‘busted’ snowfall forecast where the snow doesn’t accumulate the way we anticipate.  Because we’ve become giant children who are going to stomp our feet, because we want our special treat… and Mother Nature has just told us ‘no desert, it’s time for bed!”

Anyway… that was a completely unexpected digression, and not at all how I expected to start this post.  As far as our Saturday is concerned… we’ll have partly to mostly sunny skies across the valley, along with a persistent and gusty NW breeze.  Sustained winds around 10 to 15mph are expected, and gusts upwards of 25mph will really add to the late winter chill across the region.  Make sure you grab a good coat for whatever the day has in store for you.  Our friends in the Catskills could see a few flurries or a snow shower through the day… but nothing that part of the world isn’t used to for this time of year.

A cold night ahead as well, at least for early to mid March standards.  Mostly clear skies are likely along with continued light winds and overnight lows that should fall into the teens and low 20s.  Wind chills in the low teens and possibly single digits… reminding us that Winter won’t quit just yet.  The cold hangs with us for Sunday as well, with afternoon highs once again in the mid to upper 30s… which is a solid 5 to 10 degrees below average.  That sets the stage for one of the potentially colder nights we’ll see the rest of the season.  Winds are expected to die down early Monday morning, and these could be our Monday morning wake up temperatures…

Now, the Euro is picking up on the idea that snow pack will hold through the weekend in much of the Hudson Valley.. this may be true in some spots… not so true in others.  Take my house in Pine Bush for instance… we only had 7 or 8 inches to begin with, so that snow is about 60% gone now, and I don’t know if it will hold through the weekend… we’ll see.  But where they got 15 to 20 inches of wet snow… I’m sure they will be plenty of snow left over.  And where there is snow, overnight lows could drop into the single digits… thanks to a process known as radiational cooling.  That’s where the warmth of the day radiates back out into the atmosphere at night.  This process is maximized when winds are calm, skies are clear, and when there is a fresh snow pack.

The reason, is that calm winds allow the heat in the air to rise… the clear skies mean there aren’t any clouds to act like a blanket and lock in the warm air, preventing it from radiating out into space.  And the snow pack… is a bright white surface that reflects solar radiation during the day, keeping it cooler… where as the ground typically absorbs more solar radiation.  And so when night time comes, the white surface of the snow pack quickly radiates that heat back out to the atmosphere… where the ground is slower to radiate the heat back into the atmosphere.

So long story short… a COLD night could be ahead for Sunday night and Monday morning.

Finally… the Nor’easter Storm Recap… it’s not finished yet.  Quite simply, I was too tired to do it justice Friday night, and will wrap it up on Saturday.  I sincerely apologize for the delay… it’s just been an exhausting 10 day period.  But considering how many tangents I went off into on this post… I should have just finished the recap.

Oh well… keep an eye out for the recap on Saturday.  Have a great day!

Thursday Outlook : The Aftermath

In the last 7 days we’ve had 2 major nor’easters rip through the Hudson Valley.  In that time some parts of the region have seen upwards of 30 inches of snow.  We won’t fully know the details until the snow data rolls in over the next 12 to 18 hours… but make no mistake… the 17-18 winter is certainly going out with a BANG.  Everyone is already asking about the potential storm for this coming Monday… and we’re not going to even discuss it at this point… other than to say the pattern is very active, and it would not shock us if something headed our way for Monday… but it could also stay to our south, and it’s 5 full days away.  We’ll have more on the potential for Monday in a post later on Thursday or Thursday night… but right now, it’s looking like at best a 50/50 shot.

As far as Thursday’s concerned… a blustery, cold day for sure in the wake of our snowstorm.  Temps will rise above freezing, and that will help with the cleanup and snow melt.  We’ll have sunshine mixed with clouds… and a flurry or snow shower can’t be ruled out.  Highs right around 40° should do the trick.

We’ll have a detailed storm recap late Thursday or Thursday night… once all the snowfall data has been collected.  Have a great Thursday!

Wednesday Nor’easter Nowcasting : 6PM UPDATE

UPDATE

We are in our final stages of the Nor Easter, the storm is now gradually pulling to the east, as it does it will pull the western edge of its precipitation shield with it.  But as you can see… the band of snow is still thumping away over the eastern half of the Hudson Valley.

Snowfall rates under the green band continue at over 1 inch per hour.  Snowfall amounts have already achieved out forecast in all locations with a lot of reports of snow amounts already exceeding 10″. Below is a simulated radar for 10PM that will give you an idea of where the precip will be falling, as you can see it is concentrated along the river and points east.

In our forecast we highlighted the fact that where the heaviest bands set up we would see amounts reaching 20″and that also looks to come to fruition as well, the latest short range guidance projects that an additional 3-8 inches of snow will fall along and east of the river, this will push these locations towards the max project of our forecast. The only zones that will not verify the original forecast is the Catskills where we lowered amount this morning to account for the more easterly track.

Power outages are also beginning to blossom across the region, so the quicker we can get this snow out of here the better…

 

PREVIOUS

The snow is pouring down on the eastern half of the Hudson Valley at this hour. The center of low pressure continues to linger just east of Atlantic City, and it’s really wrapping convective bands of snow northwestward, into the Hudson Valley.

Anywhere you see green on this radar, it’s snowing moderate to heavily, and the dark green and yellow are areas where it’s near white out conditions. Snowfall rates of 1 to 2… possibly 3 inches of snow per hour are possible anywhere within this convective band of snow we’ve highlighted.

It appears that the band of snow will push NW, roughly to the eastern Catskills, before stopping it’s westward progression, and pivoting before it will eventually pull east this evening. We’ve added a red line to indicate where we believe the western edge of the convective snow band will reach. Anyone east of this red line, will likely make the adjusted snowfall forecast range of 8 to 16 inches of snow. Anyone west of that line, is going to struggle… but should make the adjusted range we put this morning of 5 to 10.

As we continue through the afternoon… all indications are that the periods of heavy snow will continue into the evening commute. Snow should begin to taper off from west to east from 6pm to 10pm. But until that time… the snow will continue to thump away, especially for the eastern half of the Hudson Valley.

8am update… NOWcasting Time:

Overnight we saw light to moderate snow impact the region with a general coating to an inch or two on the ground as everyone awoke this morning, current radar and observations support the expected lull in precipitation the is occurring in parts of the region as the precipitation is mostly scattered in nature. The snow intensity was light enough that in most locations only the grassy surfaces have seen most of the accumulations, heavier snowfall rates later today will overcome the warmer surfaces and lead to accumulations on all surfaces.

We have seen a fairly significant trend of the storm tracking further east than its westerly projected track that was showing yesterday and last night, in response we have seen the short range guidance react with a significant jump east with its snowfall projections. To put into perspective just how much of a jump, here is the NAM model from last night and then the very next run this morning. The changes in our NW zones is quite significant.

Please note that these minor adjustments to note take away from the fact that this will be a significant storm for the remainder of the region, our high end projections really have not changed much.

As you can see there has been a significant drop in projected snowfall across Sullivan,Western Ulster and Delaware Counties. A look at the HRRR model which earns its name as a (High Resolution Rapid Refresh) Model, as it runs every single hour, and you can see a similar trend starting as well..

Given that our current observations of the low pressure position all support the more easterly track, its important to put our Nowcasting into play and make some course corrections before all the other forecasts are playing catchup. Here is our revised snowfall forecast that takes into account some of the latest trends with the storm, its basically almost back to our prelim forecast. The changes are most significant across the western Catskills where forecast is dropping from 18″-24″ t0 5″-10″+ a blessing for some and a headache for the forecast. We have accounted for a lower end potential with the eight inch base accumulation and have only dropped two inches off the max total of eighteen inches, we will account for these higher potentials in our conversation about banding below average snowfall across the region will be 12″, the lower end of the forecast is really to account for any mixing in the south and lesser amounts that may fall in the western locations.

Its not uncommon to see wobbles in a storm track, wobbles of only 20-50 miles can completely change a forecast, that is why these are fluid situations and nowcasting is a part of what we do. We will continue to make adjustments if needed, we will update the time stamp on the post to help signify that there is new information. Please wrap up your morning plans and preparations as weather conditions will deteriorate quickly later this morning.

Snowfall:

Zones 1,5-  5-10 inches with localized amounts of 12″ along the eastern portions, less west 

Zones 2,3,4,6,7,8,9- 8-16 inches with the heaviest amounts occurring under the most persistent bands, locations impacted by banding may see up to 18″, Eastern facing slopes of the Catskills in zone 2 may also see up to 18″, on average most of these zones will reach  12″,Zone 9 may see the lower end if mixing occurs. 

———Note that the changes are subtle outside of the Western Catskill Mountains——-

Details:

  • Lighter snowfall begins to fill in and become more widespread and heavier between 8am-11am from south to north
  • Snow falls heavy 1-2 inches per hour with a potential number of thunder within the heaviest bands (Banding likely east of the Catskills, Exact Position to be determined)
  • A widespread 8″-16″ is expected, the higher snowfall will occur where bands of heavier snow set up and pivot over the region, under the most persistent bands we may see up to 18“+ also cannot rule out some higher amount across zone 2 where terrain enhancements may also lead to amounts near 18
  • Snowfall reductions across our most western zones to adjust for a more easterly track and shorter duration snowfall persistent upslope snowfall and linger snow showers across the Catskills will likely add to these snow totals through Friday
  • Area where banding may setup has been highlight with a dashed circle, the final track of the storm will determine if this area of banding is west or east of this forecasted position
  • Snowfall ends from West to East between 10pm-2am
  • Wind Gusts of up to 20-40MPH are possible (Outages Possible)
  • Snow is of a heavy consistency and therefore we will see additional tree damages occur (Note that even areas where an inch fell overnight there are sagging limbs)

 

 

Final Nor’easter Forecast : Wednesday 3/7/18

Timing:
– 10pm to 2am : Light snow develops from west to east, may be scattered and of varying intensity
– 2am to 10am : Light snow continues although there may be some lull’s in the precipitation between 7am-10am
– 10am to 8pm : Moderate to Heavy snow… up to 1 to 3 inches per hour with a rumble of thunder possible
– 11pm to 4am : Snow begins to taper off from SW to NE

Impacts:

-Snowfall rates will be very impressive during the height of the storm, this will makes roads extremely treacherous if not impassible during the afternoon and into the overnight
-Winds gusting between 20-40mph will create reduced visibility and also lead to more tree and power issues
-Snow will be heavy and nature and will again lead to power grid issues

Snowfall:

– Catskills (Zone 1&2) : 18 to 24 inches
– Hudson Valley (Zones 3, 4, 5, 6, 7 & 8) : 12 to 18 inches
– Extreme Lower HV (Zone 9) : 6 to 12 inches (possibly less if more rain mixes in)

Discussion:

The only true wildcard that remains with this system is where the heaviest mesoscale banding will setup during the peak of the storm, for that reason we cannot pinpoint where the maximum axis of heavy snowfall will occur. With the said it is possible that we will see and swath of snow outside of the Catskills (Zone 1/2) that reaches 24″ wherever the most impressive bands set up. This will for some be the largest snowstorm of the season for some, and may also make a top 10 ranking for March snowstorms if it reaches it full potential. While this system lacks some attributes of the Friday snowstorm this system has a lot of punch and will be very impactful to our region.

Low Confidence: Mixing in extreme lower HV?

Only real concerns in terms of the forecast with this system are across the southern most parts of zone 9 where we need to monitor the potential that warmer temps or dry slotting may cut back on snowfall totals here, for that reason we have went with a bit lower and more conservative forecast for that zone. On the flip side a colder solution with dynamic cooling once again playing a part would also bring this zone into the 12-18″ forecast as well, this bears watching.

More to Come…

We’ll likely add to this post a bit more shortly, so you may want to check for more info soon.  Otherwise, we’ll have additional posts in addition to this.  But long story short, by the time early afternoon hits… this could be what our weather map looks like.  A major nor’easter for the Hudson Valley for sure.

 

Preliminary Storm Forecast : Wednesday Nor’easter

The month of March can be a beast when it comes to winter storms.  The transition from the bitter chill of winter, to the mild breeze of spring, can bring a LOT of instability with it.  We saw an historic storm just 5 days ago, on Friday… and we are now staring down another major winter storm.  The phrase ‘adding insult to injury’ will be rather appropriate for some parts of the Hudson Valley.

Timing:
– 10pm to 2am : Light snow develops from west to east
– 2am to 10am : Light to moderate snow continues
– 10am to 8pm : Moderate to Heavy snow… up to 1 to 2 inches per hour
– 8pm to 12am : Snow begins to taper off, ending near midnight

Snow Accumulation:
– Catskills (Zone 1 & 2) : 7 to 14 inches
– Hudson Valley (All remaining zones) : 8 to 16 inches

Discussion:

Right on the heels of a monster winter storm, that still has parts of the region without power as of this forecast… we’ve got another major winter storm to contend with.  An upper level low pressure system will push southeast on Tuesday, from the upper mid-west, to the Ohio Valley.  That upper level low will help a coastal low pressure system develop in the early morning hours of Wednesday.  That storm will intensify and strengthen… pushing northward, along the east coast.

A frontal boundary out ahead of the upper level low pressure system will spread light snow into the Hudson Valley around midnight Tuesday night.  The snow will be light and even a bit scattered in nature, as the boundary won’t have a lot of moisture with it.  But the true purpose of that boundary will be to serve as the location for the coastal low to develop along shore.  With the upper level low pressure off to the west, it will shift its energy to the coast, and allow for the coastal storm to blossom Wednesday morning.

But it will take some time for that process to occur.  In the meantime, it’s likely that light snow showers will persist over the Hudson Valley during the overnight and early morning hours on Wednesday.  If the snow is light, and somewhat scattered… don’t be fooled… this is not the nor’easter, just some frontal boundary light snow out ahead of it.  As the low pressure continues to strengthen… convective bands of precipitation will set up on the north side of the low, and the low will begin to move northward.

By early afternoon on Wednesday, the front end of the convective snow banding should be making its way into the Hudson Valley.  The areas of banding are indicated by the purple shading on this map… which is indicative of snowfall rates of 1 to 3 inches per hour!  Whiteout conditions and thunder-snow are possible in these bands, as they will be like thunderstorms of snow.  Conditions will be treacherous under these bands of snow, and travel will be extremely dangerous if not impossible at times.  Along with the heavy snow, expect wind gusts over 25mph to be possible as the storm begins to wrap up and intensify.  This storm will move slowly off to the northeast, and by the evening commute, it is likely to still be snowing hard in the Hudson Valley…

As the nor’easter begins to push northeastward, and head toward Cape Cod, the western edge of the snow banding is likely to pivot over the Hudson Valley.  In short, that means instead of tapering off, it’s likely that the snow will continue through the evening commute and into the nighttime hours.  Snowfall rates could continue to be over 1 inch per hour at times.

So as you can see, this is a LONG duration event.  We are concerned that there could be power outage issues once again with this storm.  Granted, there are still parts of the area that are without power now… but this new nor’easter could cause new power outages.  While this storm won’t see a ‘fluffy’ snow… it likely won’t be quite as heavy and wet as the Friday storm.  We’re hoping that trees and power lines won’t be coated in snow quite the same in this storm, and the winds will be a bit less intense with this storm.  But with those points of optimism laid out, we are still concerned that power outages will be a problem late on Wednesday.

We’ll continue to have updates through the day on Tuesday, as well as a “Final Storm Forecast” Tuesday evening.  Be sure to check back with us often, for more updates and the latest information on what this storm may bring us.

Monday Discussion : Watching Wednesday

We’ll have a quiet but chilly start to our work week across the Hudson Valley.  Lots of sunshine and temperatures generally in the 30s to near 40° for a high on Monday.  After a chilly night Monday night with lows in the low 20s across the valley (upper teens in the Catskills)… Tuesday will see a cold start, before temperatures moderate into the low and mid 40s during the afternoon for highs.

That allows us to talk about Wednesday, which is really the only thing on everyone’s mind anyway.  We have another upper level low pressure diving into the central US, it will continue to roll eastward, into the Ohio Valley late on Tuesday.  At the same time, we’ll see a wave of low pressure develop along the front side of the upper level trough.  Where that coastal low pressure goes, will have a major impact on our weather for Wednesday…

As of Monday morning, we’ve got considerable disagreement on the track that the coastal low pressure will take.  There IS agreement on the development of this low pressure system, almost all data has it developing near the coast of VA and North Carolina.  The uncertainty is what happens next.

Track #1
The GFS and NAM models develop the coastal storm, and immediately have it hug the coast.  The storm tracks right along the coastline, and moves northward, before jumping northeast and heading toward Cape Cod.  This track is likely the result of the upper low pressure system off to our west influencing the track.  The rotation around the upper level low, likely pulls the coastal low pressure in toward the shore.  This also aids in the rapid development of the storm, and generates substantial lift.  If track #1 is correct, it would be a substantial storm for the Hudson Valley.

Track #2
The European and Canadian Models develop the low pressure, and immediately try to jump the storm out into the ocean, before gradually hooking it back toward the New England coastline.  This track would spare the Hudson Valley almost any real impacts.  We might see some light snow develop along the front edge of the trough, as the low pressure is forming… but then the substantial snow would be pulled out to sea, and off to our east… possibly impacting Long Island and NYC.

Which is right?
That’s the challenge we have ahead of us, is to figure out which track is the right one.  Right now, we have track #1 more likely, at about 65% chance to occur.  We really would like to see the European model come around to our idea, that would help boost our confidence a bit.  But the reason track #1 seems to make sense, is that the upper level low should influence the track of the coastal storm.

The upper level low pressure is deepening as it pushes eastward… in fact the GFS has the low closing off as it reaches the coast… a sign of a strong upper level low pressure.  As it deepens, the trough should begin to tilt negative, and with a negatively tilted trough, the storm should tuck in tightly along the coast… not push out to sea.  We’ll have to keep a close eye on the track, and see if this plays out the way we think.

If everything comes together the way we think it might… this could be our weather map Wednesday afternoon…

Notice that the NAM model is picking up on the dramatic lift that may be possible in the Hudson Valley.  The purple shading is indicative of snowfall rates well over 1″ per hour.  If track #1 is correct, then we’re in for a very snowy Wednesday afternoon across the Hudson Valley.  Snowfall amounts would likely near or exceed 6 inches in most locations, with someone possibly reaching double digits in terms of snowfall amounts.

Winds?
There are obviously concerns about strong winds, with portions of the Hudson Valley still without power today.  As it looks right now, the sustained winds should be less than what we saw on Friday for certain.  We could still have a few gusts that pack a punch, up over 30mph… but the strength and frequency of the strong wind gusts should be noticeably less than what we saw on Friday.

Now, we want to be clear… people should take this storm seriously.  The point we are trying to make, is that there is a difference between the size and scope of this storm, and the size and scope of the previous storm.  It is worth mentioning however, that due to the fact that this will likely be a heavy wet snow, with the gusty winds that we do anticipate with a developing nor’easter… that additional power outages will be a concern.

But let’s nail down the track first… and then once we know whether this storm will come up the coast, then we can worry about the wind and the potential for power outages.  Have a great Monday afternoon, we’ll have more updates tonight.

Winter Storm Recap : One For The Record Books 3/2/18

A very rare, and very damaging storm took aim on the Hudson Valley on Friday.  The impacts were wide ranging, and depending on what part of the Hudson Valley you live in, your experience was dramatically different.  Some of us saw a heavy rain for the majority of the storm, only picking up a slushy coating on the grass late in the afternoon on Friday.  Some of us were on the line between rain and wet snow, and spent the entire day switching back and forth from heavy rain to heavy wet snow… accumulating several inches in the process.  And then there were those of us who saw a heavy wet snow fall from sunrise to sunset on Friday… picking up anywhere from 1 to 3 feet of wet snow, and likely losing power due to trees and power lines snapping under the weight of the wet snow.

We’re going to focus on the meteorological aspects of this storm in this post.  We’re not going to get too far into the damage and power outages.  We have covered those already extensively on Facebook, and you can find a link to one of the discussions right here: Top 5 Most Damaging Storm for Central Hudson.  The damage was incredible, and worthy of it’s own discussion.  If you have time, check out this photo documentary from our good friends at Central Hudson, as they worked to restore power on Saturday.  Some of the pictures are breathtaking.
Central Hudson Storm Restoration Work.

Lastly, a point of clarification… we’re about to talk about this storm from a meteorological standpoint.  We may use descriptions of awe and wonder.  As snow lovers, we may make the storm sound ‘awesome’.  We want to be clear, that in no way are we minimalizing the hardship many people are facing as a result of lost power and damaged property.

So let’s get down to business.  We’ll begin the recap with 3 images:
– Our final snowfall forecast with our mid storm modification
– The snowfall history map
– Snowfall reports via the National Weather Service

Take a good look at that snowfall history map, you likely won’t ever see another one like it.  A literal bulls eye of rain, within a sea of heavy wet snow.  As snow lovers, Alex and I feel punched in the gut by looking at his map.  I live in the SW edge of the ‘snow hole’, and he lives in the NE edge of the ‘snow hole’.  Widespread 6 to 12 inches of wet snow… and nearly nothing at all for many in central Ulster and Northern Orange counties.

Interesting Spotter Reports
The reports out of Ulster are telling… because typically, if you underachieve in an event, or don’t get any snow… a trained spotter simply won’t call the report in.  But 2 people, one in Kerhonkson and one in Saugerties, were so irritated by this storm, that they reported the 0.1″ to the National Weather Service.  If more trained spotters had done that, the ‘snow history map’ would have been more accurate than it was.  To be honest, we believe the map shows too much snow in the ‘snow hole’.  In Pine Bush, I got 0.1″ as well, just a slushy coating on grass.  But it suggests I got 1 to 2 inches.  But aside from splitting hairs, this map paints an incredible picture.

So What Happened??
How on earth does something like this happen?  Is it magic?  Climate Change?  Do the Snow Gods just hate Bill & Alex?  While we believe the answer is actually the 3rd choice… that the snow Gods hate us… there actually is a scientific explanation.  The explanation is quite complex, but let’s walk through it step by step.

Dynamic Cooling: So remember, we were in the 50s on Thursday, and we needed to cool temperatures dramatically just to get to a place where it could snow on Friday.  The mechanism that did this, was called “Dynamic Cooling”.

This was the “vertical velocity” map we posted on Thursday.  It shows the upper level low pressure marked with the “L”.  The bright colors represent intense upward motion, or “lift” in the atmosphere.  The upper level low pressure generated very strong upward motion over the Hudson Valley.  This caused the air to rise very rapidly, which in turn caused the air to cool dramatically.  As the air cooled, it condensed, and rain began to fall heavily.  As the heavy rain fell, it pulled that cooled air back down to the surface.  As this process repeated over time, eventually the column of air was cooled enough so that SNOW was falling instead of rain.  This process is known as ‘dynamic cooling’.  Ultimately, this storm created its own cold air… which is pretty intense meteorological stuff by itself.  But then things got even more complex.

While forecasting, Alex and I began to see the models suggesting it would rain in parts of the Hudson Valley.  With the tremendous dynamic cooling we were expecting, and the heavy precipitation, this didn’t make sense.  Once cold enough to snow, we thought it should continue to snow heavily, at least until the snow eased up later in the day.  This complex riddle resulted in an hour and a half phone call between me and Alex, because we needed to talk about what the heck was going on.  To Alex’s credit… he called it.  He told me over the phone that he thought the model was detecting downsloping winds off the Berkshire Mountains.

What are downsloping winds, and why would it cause rain in the central Hudson Valley?

The winds around a nor’easter originate out of the northeast for the Hudson Valley.  So as the winds rotate around the storm, they blow through Massachusetts, and over the Berkshire Mountains.  As they do that, the air rises and cools over the Berkshires.  This part of the process is called upsloping, and results in higher snowfall amounts and colder temperatures in the Berkshires.

But as the air continues out of the Berkshires, and moves down into the Hudson Valley, the air sinks and drops in elevation.  When air sinks, the opposite happens… the air warms considerably, and dries out.  The result is quite amazing.  Temperatures were falling due to the dynamic cooling process.  At our HVW Station in Hurley, NY… check out these temperatures, and see if you can notice when the downslope effects started to be felt:
12am: 38.3°… 1am: 36.3°… 2am: 34.8°…(skip a few hours)…  6am: 34.7°… 7am: 37.8°… 8am: 38.4°… 9am: 38.1°

So the dynamic cooling had begun to take effect, and it was resulting in a change over to sleet and wet snow… but once the downsloping effect kicked in, it negated the effect of the dynamic cooling, and made it too warm to snow over a portion of the viewing area.

The map above is a bit of a crude demonstration of the location of the Berkshire Mountains, factoring in the northeast wind, and the net impact area.  Now, you might wonder why the ‘rip off’ zone or ‘snow hole’ is many miles away from the Berkshires.  The reason, is because the elevation remains rather high with the Taconics, and elevation doesn’t decrease with the Hudson Valley until you get much closer to the river.  So the downsloping effect doesn’t really kick in until you get closer to the river.

From a forecasting perspective it’s frustrating… because like I mentioned, Alex called it in our conversation.  And we then discussed it repeatedly, in both posts and live streams, as a possible wildcard.  But we hesitated to nail down a specific area, because it was not something we had seen before… at least not to this magnitude.  But now, having experienced it, we know that it can happen.  Pretty wild stuff.

Blockbuster Wet Snow

So now that we’ve highlighted the meteorological phenomenon that caused a large area in the middle of the region to get do little snow, let’s show the snow map once more, and soak in those incredible snowfall totals…

AMAZING snow totals.  Ignoring the previously discussed snow hole, and we had widespread 6 to 12 inch amounts across the  Hudson Valley.  As you went up in elevation across Dutchess and Columbia counties, you even broke 12 inches.  Unfortunately, we also saw wind gusts reports in the 30 and 40mph ranges.  When we forecasted 6 to 12 inches of wet snow, along with those wind gusts… we were concerned that power outages would become a widespread problem.  We hope that power gets restored ASAP, as it’s really tough this time of year to not have power.

Then there’s the Catskills… woo doggy… the Catskills.  Just take look at Greene county.  28 inches for Hunter, 26 inches for Windham, and similar high numbers of 1 to 3 feet across the Catskills.

This storm was truly dynamic, and when you stack it up against other historical storms… you see just how unique and significant it was.

Saturday Outlook : Blustery Winds Continue

On Saturday, we’ll begin to process what was truly a historic storm for the Hudson Valley on Friday.  If not so much in terms of impact (and there was a lot of impact)… then at least in terms of the meteorological nature of the storm.  We cannot recall a storm where it poured rain all day in southern Ulster county, while it thumped snow all day in much of Dutchess, Orange, Putnam and Rockland counties.

There will be numerous different statistics and graphics that we begin pulling together on Saturday, as the data all roll in.  So we’ll be pretty busy on Saturday as well.  We’ll try to get the snowfall totals to you first, and then we’ll worry about the other jaw dropping statistics… and there will be several.

Winds of Change

The big weather story over the next several days will be the winds.  Saturday we’ll begin to see clouds mix with sunshine, as our coastal bomb of a storm gradually drifts out to sea.  The winds wrapping around that system as it meanders away, will be quite strong.

Northeast winds 10 to 15mph, will gust over 30mph at times, as the storm continues to deepen off shore.  This could be a problem for those of us who saw upwards of 10 to 15 inches of wet snow on Friday.  If the winds continue to batter the trees and power lines that are coated with several inches of wet snow… at best, it will make the work of our local utility crews that much more difficult… and at worst, it could cause additional power outages.  Something to be aware of on Saturday… as the cleanup across the eastern half of the Hudson Valley continues.

That’s not to diminish what happened across the western half of the Hudson Valley, where parts of Orange county, Rockland County, Sullivan and Greene counties were plastered with wet snow.  But Ulster County (in general) is going to be one of the more phenomenal stories.  The bulk of the county saw less than an inch… with many places seeing 0.1″ or 0.0″ of snow.  We are still compiling the snowfall data, so ‘officially’ we don’t have the numbers… but what we’re seeing is effectively a giant snow hole right in the center of the Hudson Valley.

As a personal anecdote, it’s almost impossible for me to believe that parts of Dutchess county saw 12 to 15 inches of snow, and that Monroe (roughly 15 miles to my south) pulled in 12 inches.  All while I received a whopping 0.1″ of snow… yes I had a slushy coating late in the day on Friday, after many inches of rain had fallen.  Or that Alex, located roughly 20 to 30 miles to my northeast, also saw 0.1″ of snow… and that roughly 5 to 10 miles to his east, Rhinebeck had 6 inches of snow.  It’s truly wild stuff.

So we’ll continue to pull together the data on Saturday, and share it with you as soon as we can.  Bundle up, and be safe on Saturday… have a great day!