Major Snows Not due to AGW

[tacoman25]

Yep.......no trend in global precip. Adjusted temps have never made sense.....

Sometimes I have urge to use the Precipitation data as the temperature data. They correlated perfectly until it was adjusted, which is why I don't use the adjusted temps, or surface data in general.

That's interesting. It looks like global precip follows PDO/ENSO trends pretty closely.

[BethesdaWX]

And has DC seen a decrease in big snowstorms?

They've seen a decrease in snowfall overall, but the big time snows have actually increased. Some of this is due to the changing of measurement sites, some is due to the AO/NAO changes, the rest is Due to the Warming Climate Experienced during the past Century.

[BethesdaWX]

That's interesting. It looks like global precip follows PDO/ENSO trends pretty closely.

It does, almost to a tee actually.

Warming temps have not had an impact on precipitation....hmmmmm. This shouldn't be so.

[tacoman25]

It does, almost to a tee actually.

Warming temps have not had an impact on precipitation....hmmmmm. This shouldn't be so.

If that graph is accurate, it pretty much blows a hole in any argument that AGW is leading to bigger snowstorms. Because the only way that would be possible is if precipitation was going up.

[skierinvermont]

So you're telling me that as a general rule, the further south you go on the East Coast, the higher number of big snowstorms? Because that's what your logic depends on.

There's not much trend if we look at >20" storms, and especially if we restrict to 24-hr totals. One would need to do a more complete statistical analysis but there is some evidence that the largest snowstorms occur in the warmer locations. Baltimore has more >20" storms and >20" storms in 24 hrs than NYC. Cape Cod and RI hold some pretty massive 24-hr totals even though they are warmer than Boston or Hartford. So it does seem as if the warmer moister areas that get less seasonal snowfall are also prone to more of the largest 20+ and 30+ inch storms. As the climate warms, these areas might shift northwards and inland.

You might also experience an enhancement of temperature gradients that are responsible for major snowstorms.. while SSTs would be warmer in a warmer world, from time to time block patterns would dispell cold arctic air southwards over these warm SSTs leading to more intense storms.

[BethesdaWX]

If that graph is accurate, it pretty much blows a hole in any argument that AGW is leading to bigger snowstorms. Because the only way that would be possible is if precipitation was going up.

haha, yep its the official data. Really, this shows the water cycle has not sped up at all.

The temps that wre adjusted used to match the precip data to a tee actually

[skierinvermont]

And has DC seen a decrease in big snowstorms?

Again I think the time period has been too short and the magnitude of warming too small to look for such trends, at least at individual locations. We can probably start looking for trends regionally or globally (for example in flooding).

[nzucker]

There's not much trend if we look at >20" storms, and especially if we restrict to 24-hr totals. One would need to do a more complete statistical analysis but there is some evidence that the largest snowstorms occur in the warmer locations. Baltimore has more >20" storms and >20" storms in 24 hrs than NYC. Cape Cod and RI hold some pretty massive 24-hr totals even though they are warmer than Boston or Hartford. So it does seem as if the warmer moister areas that get less seasonal snowfall are also prone to more of the largest 20+ and 30+ inch storms. As the climate warms, these areas might shift northwards and inland.

You might also experience an enhancement of temperature gradients that are responsible for major snowstorms.. while SSTs would be warmer in a warmer world, from time to time block patterns would dispell cold arctic air southwards over these warm SSTs leading to more intense storms.

You are contradicting yourself though...first you say that the warmer locations experience heavier snowfalls because of increased moisture availability, and then you're saying the warmer climates should experience less snowstorms because the climate zones are shifting northward. If the warming climate were responsible for snowfall distribution, why would warmer places like DC have experienced record-breaking snowfall in Winter 09-10, with places like Norfolk, VA and Oklahoma City experiencing record-breaking snows in 10-11?

Also, the difference in 20" snowstorms between NYC and Baltimore can't possibly be statistically significant when you account for measurement error, changes in station locations, etc. And, just to show the inherent randomness of this factor, NYC has experienced two 20" storms and one 19" storm in the last year, so it all comes down to getting lucky. The main reason why Cape Cod and RI have bigger snowfalls is that they're closer to the ocean and receive more enhancement from Atlantic inflow....of course, one of the reasons we think that is because these locations have done so well in recent winters like 04-05. The biggest snow total in a major eastern city is probably the 44" recorded in Albany NY during the Blizzard of 1888, and they're far from any moisture sources. It's easy to be biased by recent events into thinking that patterns which don't really exist are important.

[tacoman25]

There's not much trend if we look at >20" storms, and especially if we restrict to 24-hr totals. One would need to do a more complete statistical analysis but there is some evidence that the largest snowstorms occur in the warmer locations. Baltimore has more >20" storms and >20" storms in 24 hrs than NYC. Cape Cod and RI hold some pretty massive 24-hr totals even though they are warmer than Boston or Hartford. So it does seem as if the warmer moister areas that get less seasonal snowfall are also prone to more of the largest 20+ and 30+ inch storms. As the climate warms, these areas might shift northwards and inland.

You might also experience an enhancement of temperature gradients that are responsible for major snowstorms.. while SSTs would be warmer in a warmer world, from time to time block patterns would dispell cold arctic air southwards over these warm SSTs leading to more intense storms.

Well, of course coastal locations tend to get the most intense storms. I'm talking about the entire climate zone shifting northward, as you claim. I don't see any evidence that this is occurring, and if it is, in general places like DC and NYC should not be seeing an increase in huge snowstorms just because of that.

It's quite simple: there is WAY more evidence that the big snowstorms seen over much of the country the past couple winters are due to favorable blocking patterns. There is very little evidence that ties them to AGW. And I have seen very little evidence that AGW would cause bigger, more frequent snowstorms over these areas to begin with.

[tacoman25]

Again I think the time period has been too short and the magnitude of warming too small to look for such trends, at least at individual locations. We can probably start looking for trends regionally or globally (for example in flooding).

Any comment on the graph of global precip that shows trends clearly correlated with PDO/ENSO, but not with global warming at all? Doesn't give much credence to the "increased water vapor from AGW is leading to more precip and bigger storms" claims.

[skierinvermont]

And again, no one has answered the elephant-in-the-room question: if there is evidence for increased water vapor, what about increased precip? This whole argument hinges on that.

I can confirm that Bethesda's graph of precipitation is essentially accurate. I've included the IPCC graph as the last image in this post. I don't know that any trend is expected in global precipitation. Would have to check.

Water vapor is most definitely supposed to increase, this is basic physics via the Clausian-Clapeyron equation. And it has been observed to do so (first image). It would be essentially impossible for the oceans to warm (as they most assuredly have via sea level rise, satellite, buoy, and ship measurements) and for WV not to increase.

[tacoman25]

I'm trying to follow you here...increased water vapor is not supposed to lead to increased precipitation?

It is clear from that graph that precipitation actually spikes when the globe cools (La Nina). For precipitation to be increasing there must be more storms, or at least stronger/wetter storms.

So where is the evidence that global warming produces stronger/wetter storms? And therefore, in certain circumstances, heavier snowfall?

[skierinvermont]

It's also worth noting that the error bars on the precipitation graph are extremely large.

The CRU and GHCN 1901-2005 precipitation data have trends of 1.1 +/- 1.5mm/decade and 1.08 +/-1.8mm/decade respectively. So there's a slight positive trend but the error bars are twice the magnitude of the trend itself.

The 1951-2005 trends are about -4 +/- 4.1mm/decade. So again, very large error bars. slight negative trend.

There are also other datasets with different trends and large error bars.. so this data should be used with extreme caution or not really used at all.

http://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch3s3-3-2.html

      Precipitation Trend (mm per decade) 
Series  	1901–2005  	1951–2005  	1979–2005 
PREC/L    	     –5.10 ± 3.25a  	–6.38 ± 8.78a 
CRU       1.10 ± 1.50a       –3.87 ± 3.89a       –0.90 ± 16.24a 
GHCN  	1.08 ± 1.87  	–4.56 ± 4.34       4.16 ± 12.44 
GPCC VASClimO    	     1.82 ± 5.32b       12.82 ± 21.45b 
GPCC v.3    	     –6.63 ± 5.18a  	–14.64 ± 11.67a  
GPCP    	  		–15.60 ± 19.84a 

[tacoman25]

Also, I think NH winter snowcover graph is quite telling. 2010 had the greatest snowcover since 1977...another very -A0/-NAO year. This gives credence to the idea that snowfall in the mid latitudes is much more correlated to NH blocking than anything else.

[tacoman25]

It's also worth noting that the error bars on the precipitation graph are extremely large.

The CRU and GHCN 1901-2005 precipitation data have trends of 1.1 +/- 1.5mm/decade and 1.08 +/-1.8mm/decade respectively. So there's a slight positive trend but the error bars are twice the magnitude of the trend itself.

The 1951-2005 trends are about -4 +/- 4.1mm/decade. So again, very large error bars. slight negative trend.

Doesn't change the fact that there is no evidence of increased precipitation due to warming.

[skierinvermont]

Doesn't change the fact that there is no evidence of increased precipitation due to warming.

Again, I don't know that there is expected to be much change. A lot depends on lapse rates and that is an area of considerable uncertainty.

[tacoman25]

Again, I don't know that there is expected to be much change. A lot depends on lapse rates and that is an area of considerable uncertainty.

Well then where in the hell do these people get off claiming that AGW will lead to more and bigger storms?

Again, ZERO evidence for this. I'm sick of scare tactics and blame-mongering.

[skierinvermont]

Well then where in the hell do these people get off claiming that AGW will lead to more and bigger storms?

Again, ZERO evidence for this. I'm sick of scare tactics and blame-mongering.

OK I looked it up .. precipitation is supposed to increase. The general pattern is more in the tropics, less in the subtropics, and more in the high latitudes. More precip in the high latitudes has been observed and is statistically significant.

Obviously there hasn't been a large enough change in precip in either direction, at least not large enough for our measurement systems to detect.

[nzucker]

Global warming is supposed to do everything except bring me a beer.

[tacoman25]

OK I looked it up .. precipitation is supposed to increase. The general pattern is more in the tropics, less in the subtropics, and more in the high latitudes. More precip in the high latitudes has been observed and is statistically significant.

Obviously there hasn't been a large enough change in precip in either direction, at least not large enough for our measurement systems to detect.

More evidence that, if anything, most places should be seeing less snow with AGW, not more.

[skierinvermont]

More evidence that, if anything, most places should be seeing less snow with AGW, not more.

The northeastern U.S. is projected to see more precip, as is Canada. I wouldn't classify the NE US as subtropical. This is especially true in winter.

You can just go to the IPCC report and look at the multi-model mean change in precipitation global map..

http://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter10.pdf

page 769

[tacoman25]

Obviously there hasn't been a large enough change in precip in either direction, at least not large enough for our measurement systems to detect.

And that's why my initial question was, ok, so water vapor has supposedly gone up 5-6% over the past 100 years...shouldn't there be an observable increase in precipitation then?

And contrary to WeatherRusty's earlier assertion, the warmest years have NOT been the wettest years. The opposite is actually true, since La Ninas produce more global precip and El Ninos less.

[tacoman25]

The northeastern U.S. is projected to see more precip, as is Canada. This is especially true in winter.

Why? Why would global warming cause an increase in precip in the NE U.S., even though the sub-tropics are supposed to be seeing less precip overall?

The NE U.S. is definitely not the tropics and definitely not the Arctic. It's in between, what would you call that? In any case, the mid-latitudes are supposed to see less precip overall, correct?

[skierinvermont]

And that's why my initial question was, ok, so water vapor has supposedly gone up 5-6% over the past 100 years...shouldn't there be an observable increase in precipitation then?

And contrary to WeatherRusty's earlier assertion, the warmest years have NOT been the wettest years. The opposite is actually true, since La Ninas produce more global precip and El Ninos less.

I think Rusty was referring to warmer in a more general sense.. as in every one of the last 15 years would classify as a warm year.

But yes.. you are correct that Ninas have more global precip than Ninos.. well documented phenomenon.

[skierinvermont]

Why? Why would global warming cause an increase in precip in the NE U.S., even though the sub-tropics are supposed to be seeing less precip overall?

The NE U.S. is definitely not the tropics and definitely not the Arctic. It's in between, what would you call that? In any case, the mid-latitudes are supposed to see less precip overall, correct?

Because we're not exactly sub-tropical.. just look at the graph.. sub-tropical was just a general descriptive adjective used by the authors.. the actual models results are much more descriptive.

[tacoman25]

I think Rusty was referring to warmer in a more general sense.. as in every one of the last 15 years would classify as a warm year.

But yes.. you are correct that Ninas have more global precip than Ninos.. well documented phenomenon.

Either way, the last 15 years certainly weren't the wettest. 1998 and 2005 were not wet years. His comment had no statistical basis.

And the fact that global precip increases when the oceans and land cool (larger, wetter, more frequent storms overall) does not give any support to the idea of AGW producing larger, wetter storms.

[skierinvermont]

You are contradicting yourself though...first you say that the warmer locations experience heavier snowfalls because of increased moisture availability, and then you're saying the warmer climates should experience less snowstorms because the climate zones are shifting northward. If the warming climate were responsible for snowfall distribution, why would warmer places like DC have experienced record-breaking snowfall in Winter 09-10, with places like Norfolk, VA and Oklahoma City experiencing record-breaking snows in 10-11?

It's not a contradiction.. eventually you simply become too warm to snow at all. I think you know exactly what I meant and you are just playing games.

I also have never said that the warming climate was responsible for the snowfall in DC. In fact I have said the exact opposite, a warming climate should decrease the frequency of heavy snowfalls in DC and Norfolk. I've said that several times in this thread, and we both said it on our radio show. I think you know that and you are yet again playing games.

[BethesdaWX]

OK I looked it up .. precipitation is supposed to increase. The general pattern is more in the tropics, less in the subtropics, and more in the high latitudes. More precip in the high latitudes has been observed and is statistically significant.

Obviously there hasn't been a large enough change in precip in either direction, at least not large enough for our measurement systems to detect.

Decreasing Precip at Mid Lattitudes would lead to less snowcover in the winter...there hs been no trend. The Arctic precipitation has increased due the the positive trend of the AO/NAO over the past several decades...until recently, that is.

The Tropics have not shown increased precip that follows the temperatue trend.

This shows that we again, do not understand the energy function of our planet very well at all, and is why AGW is still hypothesis. NOW.............you think e can understand how Solar/IR, MagF, GCC, DOC, GCR...etc..........effect the globe....and do it with ANY accuracy whatsoever? ol:

[skierinvermont]

Either way, the last 15 years certainly weren't the wettest. 1998 and 2005 were not wet years. His comment had no statistical basis.

And the fact that global precip increases when the oceans and land cool (larger, wetter, more frequent storms overall) does not give any support to the idea of AGW producing larger, wetter storms.

Well then I would have to disagree with Rusty.. as there is no observational basis (yet) to say precip has increased. Our observation network is pretty inadequate though especially over the places that the change is supposed to occur (arctic) so this doesn't concern me very much. The global change is also projected to be fairly small, given the sub-tropical drying.

The fact that global precip is higher during Ninas years doesn't negate the idea that global precip will be higher in a warmer world. Climate models accurately simulate heavier precip during Ninas, but they also project an underlying long term increase. I think the mechanism for this is pretty apparent. There is an underlying upwards trend in water vapor due to the Clausian Clapeyron equation and warming SSTs. During Ninas the global temperature falls and you experience a temporary spike in precip.

[skierinvermont]

Decreasing Precip at Mid Lattitudes would lead to less snowcover in the winter...there hs been no trend. The Arctic precipitation has increased due the the positive trend of the AO/NAO over the past several decades...until recently, that is.

The Tropics have not shown increased precip that follows the temperatue trend.

This shows that we again, do not understand the energy function of our planet very well at all, and is why AGW is still hypothesis. NOW.............you think e can understand how Solar/IR, MagF, GCC, DOC, GCR...etc..........effect the globe....and do it with ANY accuracy whatsoever? ol:

I didn't say mid-latitudes. I said sub-tropics. For anybody that is unclear here is the region generally regarded as being the sub-tropics. The mid-latitudes on the other hand are generally any region between 30 and 60N. It's sort of sad that I have to explain this.. people just too eager to disagree with what I say.

For christ's sake people.. just look at the model projections yourselves instead of relying on my description of the results:

http://www.ipcc.ch/p...1-chapter10.pdf

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