Historic Storm frequencies increasing?

[scottmartin49]

"uh, trees are used in climate science.

and please, let's not derail this thread with false accusations about professional climate scientists."

 

WXTRIX;

 

You're projecting dear, and failing to 'close read'. I'd love to parse this 'intervention style', but really don't have the time to help reform the awkward social skills of practicing scientists. In re: convincing skeptics, you're not helping.

 

Best...

[Jonger]

I disagree. I think trained observer -- Certified observer when they switched over from FAA Flight Service stations (human) there were more in the 90s than there are now. The art actually is pretty lost, and the data sets for snow frankly suck-- I.E ASOS can not measure snow) only snow precip amount. If you are talking spotters that's different or even COOP Observers which do not record thunder.

 

But I would echo what others have said at least in Northern New England cold season. There are anecdotal more cold season thunderstorms and thunder snows, not to be picayune but probably more snow pellet thunder-snows.  During the 1993 blizzard at KMPV we recoded 3 hours I believe of thundersnows with snowfall rates around 3 to 4" an hour straight - it was special!!!

 

I'm far more concerned with the thundersnow topic that snowstorm measurements. I'm sure there were some accurate weather weenies back in the day, but wide spread weenies reporting thundersnow was almost certainly a fraction of todays.

[Jonger]

"uh, trees are used in climate science.

and please, let's not derail this thread with false accusations about professional climate scientists."

 

WXTRIX;

 

You're projecting dear, and failing to 'close read'. I'd love to parse this 'intervention style', but really don't have the time to help reform the awkward social skills of practicing scientists. In re: convincing skeptics, you're not helping.

 

Best...

 

She has the social communication skills of Sheldon Cooper, don't feel bad.

[bluewave]

A new study will be out soon documenting the increase in extreme snowstorms which

is in line with the increase in winter precipitation extremes  that we have seen.

 

 

http://www.wunderground.com/blog/24hourprof/show.html?entrynum=31

 

http://hosted.ap.org/dynamic/stories/U/US_SCI_SNOW_GLOBAL_WARMING?SITE=AP&SECTION=HOME&TEMPLATE=DEFAULT

 

 

[tamarack]

From the first link:

"Presumably, the red (hail) and dark pink (graupel) shown on the 0218Z image of hydrometeor classification were erroneously selected because there must be a red flag in the HC algorithm that automatically eliminates snowflakes as the possible dominant hydrometeor when radar reflectivities are 40 to 50 dBZ or higher. In effect, these very high radar reflectivities likely "overruled" other dual-pol metrics (such as differential radar reflectivity) that probably indicated otherwise."

The obs thread for the Feb 8-9 storm included several posts from folks within that super-intense band reporting hail or "ice chunks" pelting down. Though I've not read/heard of any official confirmation, is it possible there was no error, that the intense thundersnow-producing convection actually included some hail? Of course, this in itself would be evidence of a very rare degree of storm intensity.

[skierinvermont]

Ok if warmer moister air produces more heavy snowfalls (say >18") why does NYC see more major snowfalls than Richmond Virginia? Richmond is certainly surrounded by much warmer moister air than NYC is during the winter. 

[WeatherRusty]

Ok if warmer moister air produces more heavy snowfalls (say >18") why does NYC see more major snowfalls than Richmond Virginia? Richmond is certainly surrounded by much warmer moister air than NYC is during the winter. 

 

The phasing of the southern and northern jets typically occures further north of Virginia, so the intensity of storms is greater further north. Also, eastern Virginia is less frequently sufficiently cold to support deep snows even on the cold side of a storm. Make sense?

[skierinvermont]

The phasing of the southern and northern jets typically occures further north of Virginia, so the intensity of storms is greater further north. Also, eastern Virginia is less frequently sufficiently cold to support deep snows even on the cold side of a storm. Make sense?

 

The phasing occurs further north because of where the thermal gradient typically sets up. As the earth warms, the phasing shifts even further north. What we will witness with warming is a shifting north of the climate zones. Right now I'm pretty sure Boston sees more major snows than NYC, NYC more than Philly, Philly more than Baltimore, Baltimore more than DC, DC more than Richmond. As the climate warms, these zones will shift north. 

 

You can't expect warmer moister air, but then for the phasing to still occur in the same place. 

[ORH_wxman]

I'm about half done putting together big snowfall totals at the major stations in SNE, but its a bit time consuming (more than I thought it would be) and also haven't had a ton of free time recently. There has definitely been an uptick in 18"+ events here which is distinct in the 1993-current period. However, several interesting problems arise when trying to determine how robust this trend is...one is homogenius record sites (sites changed to airports between the 1920s-1940s) and the other is measuring technique which is a big deal in large snowfalls. The 2000s have seen the most 18"+ events for BOS/ORH/BDL/PVD combined than any decade. The 1960s are 2nd. An absolute dearth of them in the "warm" 1930s (how come this warm decade didn't produce extreme snowstorms but the cold 1960s did?).

 

I think for northeast extreme snowstorms, a positive link to global warming could start with blocking in the NAO region. If global warming increases blocking there, then this increases the chances of a long duration heavy snow event happening in any given winter. But this link has not been made yet with any convincing evidence.

 

 

I'm in somewhat agreement with skier that I am having a hard time understanding how warmer weather makes extreme snowstorms more likely. Our warmer winters typically lack large KU type snowstorms. I understand the precip link, but it still needs to be cold enough to snow and there is a limit in how much moisture cold air holds. Perhaps the paper linked in here when it is published will have some definitive answers that also address the issue of homogenius recording sites and measurement techniques. I'll be interested to read it.

[skierinvermont]

The phasing occurs further north because of where the thermal gradient typically sets up. As the earth warms, the phasing shifts even further north. What we will witness with warming is a shifting north of the climate zones. Right now I'm pretty sure Boston sees more major snows than NYC, NYC more than Philly, Philly more than Baltimore, Baltimore more than DC, DC more than Richmond. As the climate warms, these zones will shift north. 

 

You can't expect warmer moister air, but then for the phasing to still occur in the same place. 

 

bump for Rusty b/c of new page

[skierinvermont]

I'm about half done putting together big snowfall totals at the major stations in SNE, but its a bit time consuming (more than I thought it would be) and also haven't had a ton of free time recently. There has definitely been an uptick in 18"+ events here which is distinct in the 1993-current period. However, several interesting problems arise when trying to determine how robust this trend is...one is homogenius record sites (sites changed to airports between the 1920s-1940s) and the other is measuring technique which is a big deal in large snowfalls. The 2000s have seen the most 18"+ events for BOS/ORH/BDL/PVD combined than any decade. The 1960s are 2nd. An absolute dearth of them in the "warm" 1930s (how come this warm decade didn't produce extreme snowstorms but the cold 1960s did?).

 

I think for northeast extreme snowstorms, a positive link to global warming could start with blocking in the NAO region. If global warming increases blocking there, then this increases the chances of a long duration heavy snow event happening in any given winter. But this link has not been made yet with any convincing evidence.

 

 

I'm in somewhat agreement with skier that I am having a hard time understanding how warmer weather makes extreme snowstorms more likely. Our warmer winters typically lack large KU type snowstorms. I understand the precip link, but it still needs to be cold enough to snow and there is a limit in how much moisture cold air holds. Perhaps the paper linked in here when it is published will have some definitive answers that also address the issue of homogenius recording sites and measurement techniques. I'll be interested to read it.

 

 

Well i think there is a difference between warmth globally and warmth regionally. While the 30s might have been nearly or equally as warm as the 2000s in SNE, that would probably be associated with SE ridging which is not conducive to slow moving heavy snowstorms. Whereas today we can achieve warmer temperatures during blocking regimes than could be achieved previously.

 

 

However I still don't think my original question has been insufficiently answered. If warmth and moist make for more frequent heavy snows (say >18") why do NYC and BOS see more than DCA and RIC? Rusty says because of the prevailing storm track. But that track should shift even farther north in direct proportion to the increase in temperature and moisture. 

 

 

As I suggested the change in snowfall should have much more to do with how AGW effects persistent blocking regimes. 

[ORH_wxman]

Well i think there is a difference between warmth globally and warmth regionally. While the 30s might have been nearly or equally as warm as the 2000s in SNE, that would probably be associated with SE ridging which is not conducive to slow moving heavy snowstorms. Whereas today we can achieve warmer temperatures during blocking regimes than could be achieved previously.

 

 

However I still don't think my original question has been sufficiently answered. If warmth and moist make for more frequent heavy snows (say >18") why do NYC and BOS see more than DCA and RIC? Rusty says because of the prevailing storm track. But that track should shift even farther north in direct proportion to the increase in temperature and moisture. 

 

 

As I suggested the change in snowfall should have much more to do with how AGW effects persistent blocking regimes. 

 

 

Well the 1930s were def warmer than the 1960s globally as well, not just in the Northeast...but you are right there are regional patterns that are extremely important. The most tightly clustered periods of KU events were during anomalous NAO blocking regimes. The 1960s had several of them, and just recently we had an amazing 2 winter run in 2009-2010 and 2010-2011...this where I think the research should be focused for snow events in the northeast. IF global warming can be linked to anomalous winter -NAO patterns. (the 1960s are a problem in this argument though)

 

Before the 2009-2011 onslaught, since 1956 (when the KU study starts analyzing storms), we had a slight negative trend in KU events. Given the volatility of the data set, it was essentially zero. The recent burst of 8 KU storms in 3 years has all of the sudden made people search for answers with global warming. Perhaps it is warranted, but the data is so noisey and tends to be clustered historically. I'm not surprised the new study that is coming out decided to cluster the 1960s into the current period to show the big increase, because prior to the 1960s (really late 50s), the KU type storms are at a dearth. However, hopefully they reconcile siting and measuring techniques in the study because this is a big factor.

 

 

I'll be interested to read it though.

[ORH_wxman]

As I suggested the change in snowfall should have much more to do with how AGW effects persistent blocking regimes. 

 

 

Sorry, I didn't see this part the first time, you may have added it in right before I replied, or I just missed it....but I agree obviously, as per my 2 previous posts.

[WeatherRusty]

The phasing occurs further north because of where the thermal gradient typically sets up. As the earth warms, the phasing shifts even further north. What we will witness with warming is a shifting north of the climate zones. Right now I'm pretty sure Boston sees more major snows than NYC, NYC more than Philly, Philly more than Baltimore, Baltimore more than DC, DC more than Richmond. As the climate warms, these zones will shift north. 

 

You can't expect warmer moister air, but then for the phasing to still occur in the same place. 

 

Agreed, but we may be experiencing a transition period where there is still plenty of temperature differential for these really big storms to develop in. During Nemo the temp where I am hovered near 21F for most of the storm, while off shore the sea water temps were a few degrees above the normal. As much as 2 1/2 feet of snow fell around here. It's not really the low temp that matters as much as the depth of the cold air situated over the area, the futher north the deeper and more entrenched the cold air.

 

As the region warms due to global warming I would expect the average depth of the cold air pool to move northward along with everything else mentioned. However, consider that as the globe warms the amplitude of waviness seen in the northern jet will increase while the globe is actively warming, so we need to consider east/west temperature gradients as well as north/south. The added moisture feeds the storms from the south and east and where it remains condusive to snow, it will snow all the more. For now, marginal conditions will penetrate south to the mid Atlantic region, in the futher not so often.

[skierinvermont]

Agreed, but we may be experiencing a transition period where there is still plenty of temperature differential for these really big storms to develop in. During Nemo the temp where I am hovered near 21F for most of the storm, while off shore the sea water temps were a few degrees above the normal. As much as 2 1/2 feet of snow fell around here. It's not really the low temp that matters as much as the depth of the cold air situated over the area, the futher north the deeper and more entrenched the cold air.

 

As the region warms due to global warming I would expect the average depth of the cold air pool to move northward along with everything else mentioned. However, consider that as the globe warms the amplitude of waviness seen in the northern jet will increase while the globe is actively warming, so we need to consider east/west temperature gradients as well as north/south. The added moisture feeds the storms from the south and east and where it remains condusive to snow, it will snow all the more. For now, marginal conditions will penetrate south to the mid Atlantic region, in the futher not so often.

 

If temperatures have warmed enough to shift temperature zones 100 miles north (BOS is now like NYC, NYC is like PHL, PHL is like BWI, BWI is like DCA, DCA is now like RIC) then phasing should also occur 100 miles north. 

 

Thus BOS should now see approximately the same >18" snow frequency as NYC did historically, NYC as PHL, PHL as BWI, BWI as DCA, and DCA as RIC.

 

You're basically suggesting that temperatures and moisture warmed before/more than than phasing shifted north. 

 

The east coast sees a pretty linear increase in >18" storm frequency as you drive north. It's not like PHL was the optimal place before and this zone is now shifting north into NYC and BOS. As the climate warms I can't think of any reason, except an increase in blocking, that would cause anything other than a linear shift in climate zones northwards. 

 

I think you hit on the key though. If blocking increases then major snowstorms will as well. The 2000s have seen a lot of big snows, but it has also seen a lot of blocking. Perhaps the blocking explains the # of storms and not warming temperatures (directly). So then the question is, does warming explain increased blocking?

[tamarack]

The phasing occurs further north because of where the thermal gradient typically sets up. As the earth warms, the phasing shifts even further north. What we will witness with warming is a shifting north of the climate zones. Right now I'm pretty sure Boston sees more major snows than NYC, NYC more than Philly, Philly more than Baltimore, Baltimore more than DC, DC more than Richmond. As the climate warms, these zones will shift north. 

 

You can't expect warmer moister air, but then for the phasing to still occur in the same place. 

 

The data I've found bears this out, though it's not all that linear.  Below are #1 and #15 storms plus 18"+, for 10 locations on I-95.  Data is thru 2011 - I know PWM broke its #1 earlier this month, and some other stations may have had top 15s (BOS/PVD?), but other than for PWM I don't have the numbers.  RIC thru NYC all have records 110+ yr (at/near current location), PVD and north, 65-90 yr.

 

Location...#1.....#15...18"+

RIC........21.6...10.6.....2

DCA.......28.0...12.0....3

BWI.......28.2...13.1...10

PHL.......30.7...14.1....8

NYC.......26.9...17.4...10

PVD.......28.6....12.1...5

BOS.......27.6...16.5...12

PWM.....27.1....16.3....8

BGR......30.9....17.5...12

HUL.......29.2....16.6....8

 

For top 15 storms, 1960s is the prime decade, with avg 2.6 of the 15s landing there, 6 each for PVD and BGR.  Next is 2000s, avg 2.1, including 4 for BOS.  Lowest decades 1950s on (some of the 10 stations' records begin 8/1948) are '50s with 1.3 and '80s with 1.35. 

 

For the 5 stations with the longer records, the 1910s had only 3 top 15s, for avg 0.6.  2000s are the winners for the "old 5", with avg 2.2, but they've had 8 added to their top 15s in 2010-11, which would avg 1.6 each if no more occurred thru 2019.   For DCA/BWI/PHL/NYC, 17 of their collective 60 top storms of the past 110+ yr have come in the 9 yr 2003-11.  SSS, but 28% in the most recent 8% of the records period.

[WeatherRusty]

It's one thing to expect storm tracks to move northward, but quite another to explain why the storms are becoming more juicy....if they are. Warming should generally cause a northward movement of the jetstreams and the weather associated with them, including phasing. Juicier storms should result from greater PWAT feeding into the storms, even as temperature differentials decline since saturation vapor pressure inreases exponentially with temperature rise.

[FPizz]

I haven't read the entire thread, but has the average winter precipitation increased a lot over this region as well, and not just bigger snowstorms? Has precip increased yearly as well? I think I remember a yearly chart showing increased precip over the decades, but I don't remember seeing one only showing the winter months.

[skierinvermont]

It's one thing to expect storm tracks to move northward, but quite another to explain why the storms are becoming more juicy....if they are. Warming should generally cause a northward movement of the jetstreams and the weather associated with them, including phasing. Juicier storms should result from greater PWAT feeding into the storms, even as temperature differentials decline since saturation vapor pressure inreases exponentially with temperature rise.

 

A storm at location X has greater PWAT. But a storm along the mean jet would probably have nearly the same PWAT in a warmer or colder world because the jet shifts north at the same rate as PWATs do. If the mean storm track shifts 300 miles north, from Baltimore to NYC in the next 50 years, then NYC will likely have the same PWATs Baltimore does today. Also the same temperatures. 

 

There are way bigger PWATs in Richmond than NYC in winter. But almost all noreasters track north of RIC. By the time NYC has the same PWATs as RIC, the jet stream will also be far enough north that phasing generally will occur north of NYC. Storms in NYC will have much bigger PWATs than they do today and be much "jucier" as you say, which will mean more winter rainfall but not more snowfall. 

 

 

In order to show an increase in snowfall, I think you need to show that PWATs will shift northwards faster than the jet will AND/OR that blocking will increase. 

[skierinvermont]

The data I've found bears this out, though it's not all that linear.  Below are #1 and #15 storms plus 18"+, for 10 locations on I-95.  Data is thru 2011 - I know PWM broke its #1 earlier this month, and some other stations may have had top 15s (BOS/PVD?), but other than for PWM I don't have the numbers.  RIC thru NYC all have records 110+ yr (at/near current location), PVD and north, 65-90 yr.

 

Location...#1.....#15...18"+

RIC........21.6...10.6.....2

DCA.......28.0...12.0....3

BWI.......28.2...13.1...10

PHL.......30.7...14.1....8

NYC.......26.9...17.4...10

PVD.......28.6....12.1...5

BOS.......27.6...16.5...12

PWM.....27.1....16.3....8

BGR......30.9....17.5...12

HUL.......29.2....16.6....8

 

For top 15 storms, 1960s is the prime decade, with avg 2.6 of the 15s landing there, 6 each for PVD and BGR.  Next is 2000s, avg 2.1, including 4 for BOS.  Lowest decades 1950s on (some of the 10 stations' records begin 8/1948) are '50s with 1.3 and '80s with 1.35. 

 

For the 5 stations with the longer records, the 1910s had only 3 top 15s, for avg 0.6.  2000s are the winners for the "old 5", with avg 2.2, but they've had 8 added to their top 15s in 2010-11, which would avg 1.6 each if no more occurred thru 2019.   For DCA/BWI/PHL/NYC, 17 of their collective 60 top storms of the past 110+ yr have come in the 9 yr 2003-11.  SSS, but 28% in the most recent 8% of the records period.

 

 

Nice job. Looks like there is not much increase north of BWI which means these places probably won't see much of a decrease with AGW until the 2050s or later. RIC DC and BWI will see the first noticeable decreases. Again, I think it mostly depends on how blocking patterns change. 

[WeatherRusty]

A storm at location X has greater PWAT. But a storm along the mean jet would probably have nearly the same PWAT in a warmer or colder world because the jet shifts north at the same rate as PWATs do. If the mean storm track shifts 300 miles north, from Baltimore to NYC in the next 50 years, then NYC will likely have the same PWATs Baltimore does today. Also the same temperatures. 

 

There are way bigger PWATs in Richmond than NYC in winter. But almost all noreasters track north of RIC. By the time NYC has the same PWATs as RIC, the jet stream will also be far enough north that phasing generally will occur north of NYC. Storms in NYC will have much bigger PWATs than they do today and be much "jucier" as you say, which will mean more winter rainfall but not more snowfall. 

 

 

In order to show an increase in snowfall, I think you need to show that PWATs will shift northwards faster than the jet will AND/OR that blocking will increase. 

 

In terms of climate, or the average to be expected type weather, what you are describing is in line with general expectations as I understand them. What of individual storms where enough cold air is present to support heavy snows? Shouldn't we expect an increase in high precipitation events with some of them being big snow producers?

[skierinvermont]

In terms of climate, or the average to be expected type weather, what you are describing is in line with general expectations as I understand them. What of individual storms where enough cold air is present to support heavy snows? Shouldn't we expect an increase in high precipitation events with some of them being big snow producers?

 

OK let's clarify there are two separate questions being asked and answered here:

 

1. If a X storm is cold enough for snow, will AGW increase the heaviness of the snow by increasing moisture?

 

2. Will AGW increase the frequency of heavy snows in X location?

 

 

The answer to 1 is, of course, always yes. But that doesn't provide us with any practical information on whether location X (say NYC) will see an increase or decrease in heavy snow storms. And when we talk about causation most people are thinking of question #2. Yes AGW will increase PWATs and precipitation rates when it's cold enough in NYC, but if in the future it is almost never cold enough to snow we probably wouldn't say "AGW is causing heavy snow to increase in NYC." 

 

 

The answer to question #2 I believe is probably NO for most locations in the eastern U.S. except perhaps for far northern locations like Caribou ME or Burlington VT. Most other locations are on the southern periphery of heavy snow storm climatology. AGW will cause phasing to occur further north and thus decrease major snow frequency. First for the extreme southern areas, like DC and RIC, then for PHL to NYC. In the near term, PHL to Boston is likely to see little change as the increase in PWATs approximately offsets the further north storm track.

 

 

 

This all assumes that PWATs move northwards at the same rate as storm track. It also assumes no change in blocking.

 

Both assumption are likely at least partially false. But I believe they are the only valid arguments for a change in heavy snow frequency. Relying upon an increase in PWATs, and question #1 above, alone, is not a valid argument IMO. I haven't seen anybody challenge either assumption. 

[PottercountyWXobserver]

     It is just a theory of mine but I will give my two cents. The reason the storm track hasn't shift much in the winter time frame during a warming world is because of the extreme arctic blocking and the increasing thermal gradient between a relatively "cold" continent during arctic outbreaks caused by the increased blocking and the warmer than average SSTs off the NE coast. The storm tracks are staying consistent because they are sniffing out the increasing thermal boundary,  for winter months anyways. Because the thermal boundaries are decreasing in spring through fall months, as supported by decreasing severe wx events. When we do see these intense blocking events, the arctic air displaces south enough to meet up with the warm and juicier airmasses from the south, and the storm tracks are remaining and increasing in frequency along the thermal boundary of the warmer winter SSTs and the "cold enough" continent of the NE.

      Meanwhile in the warming world, these intense blocking events are causing the arctic to torch to record warmth while its displaced south. You can also make an argument places in the southern US are also seing an increased chance at snow events because of the record blocking. See Houston, TX snowfall events, as I believe winters have had a greater chance of seeing snow because of the torching arctic. But I believe the case of heavier snowfall events and overall less seasonal snowfall is the trend. I can also see how in the warming world for a more disorganized jetstream ie more meridional flow in the winter months. In the future, this is just a IMHO, I can see record snow events in the winter time frame because of a cutoff low because the flow is so stagnant from blocking ( ex Great Appalachian Nov 1950 snow event). Heck I think I read somewhere where cutoff lows are increasing during the year, I don't know if that is correct though. When we don't see periods of blocking, I believe in the future is when our winter temps will beging to trend with warmth as the jetstream begins to also show the migration northward.

     Wereas in the summer months, we are seeing a much futher north jetstream causing places to bake in the mid west as I believe a semi permanent high pressure will set up there in the summer as arctic sea ice and the cold source continue to deminish during the summer months. Everyone always points out the lack of global warming during the winter months because the trend is flat or very slight warming for months like January. However, I believe the trend is hidden, but will show its ugly head eventually. The reason I say the warming trend for January is hidden, is because our "cold" air to keep us average is still taking place because of the RECORD blocking, this is causing an otherwise cold arctic to displace the "colder" air into the conus and at the same time torching the arctic to record winter warmth, but our steady US winter temps is a fake trend at the expense of the arctic blocking. I also think this theory of the hidden winter warm trend in winter holds merrit because of the lack of extreme arctic air. This is supported by cities that are having a hard time seeing true arctic air either via < -10s, -0s, 0s, or 10s depending on geographic location. I think NYC has great examples of this in all temperature months. I know this is true for summer months for my home town. Where it was possible to once get low temps in the summer time around 36-40 at night on occasion in July-Aug, that trend doesn't happen anymore. But I can make cases for this in winter months as well.

[TerryM]

The northern boundary for tornadoes has marched northward. Has there been a diminishing number of tornadoes in the south that would balance this? 

 

Terry

[WXheights]

The northern boundary for tornadoes has marched northward. Has there been a diminishing number of tornadoes in the south that would balance this? 

 

Terry

 

In general I think yes, with increased blocking higher indices slower flow per Jennifer Francis work etc maybe tornadoes in BC and the gulf coast per larger Rossby waves...