Wunderground Meteorologist Shaun Tanner

Can I Get Some Feedback? Part 2

By: shauntanner, 6:52 PM GMT on January 29, 2010

Now, let's get down to the nitty-gritty. Yesterday, I posted about the somewhat "up-in-the-air" nature of positive and negative feedback mechanisms in relationship to our environment and climate change. If you need to catch up or would like to read it, just go back to my blog directory and go for it.

One of the most important positive feedback mechanisms, and also one of the least understood, regards the oceans. You see, the biggest storage of CO2 on our planet is actually in the oceans. The ocean absorbs CO2 at a rate many, many times faster than the atmosphere does. Thus, the interaction of the atmosphere with the ocean is imperative to counteract the amount of CO2 we are putting into the atmosphere via burning of fossil fuels. But, there is a caveat. It seems as though the ocean absorbs less and less CO2 for every degree of temperature rise. So, the positive feedback mechanism I stated above should become apparent. Rising temperatures---->less CO2 absorption by ocean---->more CO2 in atmosphere---->rising temperatures---->less CO2 absorption by ocean...and the cycle continues.

This positive feedback mechanism has always assumed and some climate models have even implemented it in one way or another. Note that I said some climate models. Other models have omitted the mechanism possibly because it wasn't fully understood, possibly because it wasn't included in one of the goals of the model. Who knows? You would have to ask each particular model author.

The other question regarding the feedback has to do with the actual decay of the absorption with rising temperatures. That is, how fast is the decay? Is it cut in half with a one degree rise in temperature? Does it go down only by a few parts per million? Complicating an already complicated idea is the fact that as temperatures rise, vegetation (trees, bushes, etc.) take in less atmospheric CO2. With rising temperatures, trees tend to "breath" less efficiently and decay quicker. Decaying trees release CO2 into the air as well. So, taking this all in, past models have set the value of natural ecosystem CO2 increase per degree Celsius of warming at nearly 40 parts per million (ppm). To translate, that means that every time temperatures increase by one degree Celsius, the naturual ecosystem (oceans and vegetation) allow 40 more molecules of CO2 per million parts of air to go back into the atmosphere. That is a very high number and should be alarming.

But, is it a correct number? Who came up with the number? A new study published in Nature tries to tweak this number. The conclusion of the international study was that this number of 40 ppm should be revised downward...to 7.7 ppm. This is significant. For every degree of Celsius warming, the natural ecosystem does not put 40 ppm of CO2 into the air, but only 7.7 ppm?

Well, if you read that article, the headline and conclusion of the study are confusing. The headline states, "Temperature and CO2 feedback 'weaker than thought'". The number the study comes up with is 7.7 ppm, but the actually range is set somewhere "between 1.7 and 21.4 parts per million." So, whatever the actual number could be, it could be as high as 21.4 ppm.

Also, even if the real magic number is 7.7 ppm it might not be that significant. As I stated earlier, some climate models include this carbon cycle while others do not, yet nearly all show significant warming. So, I find the most important quote in the article to be:

"It might lead to a downward mean revision of those (climate) models which already include the carbon cycle, but an upward revision in those which do not include the carbon cycle."

So, everything is a wash. Those that did include the cycle may be trended downward (by still warming), while those did not have the cycle will be revised warmer. While this may be something skeptics will latch on to, in the end it doesn't really mean anything in the final argument. We need to know more about the interaction with the ocean and the atmosphere.


Can I Get Some Feedback?

By: shauntanner, 7:48 PM GMT on January 28, 2010

I will be the first to admit that Global Warming science is far from clear-cut. There are many things we simply do not know and many other things that are barely known. Having said that, I am firmly on the side of the argument that says humans are the main cause of climate change. Even if I wasn't, simply logic would put me in the mindset that we should wean ourselves from dirty oil and start to gobble up cheaper alternative fuels right now. I find it absolutely ludicrous that with all of our technology we can't seem to harvest the energy from the sun.

As I watched the State of the Union last night, President Obama said it best when he mentioned that we all don't have to agree about the science of global warming to agree that a switch to alternative energy will benefit our country enormously. Cheaper energy, more jobs, cleaner skies. Who in the world can argue with that?

One of the most complicated areas of the Global Warming debate to understand is feedback mechanisms. Basically, there are two types of feedback mechanisms...positive and negative. A positive feedback is where a change in the system only acts to reinforce that change. For instance, a classic positive feedback would be...rising temperatures---->more evaporation---->more water vapor in the atmosphere (greenhouse gas)---->rising temperatures---->more evaporation.....you get the point. Another positive feedback would be rising temperatures---->ice melts--->more solar radiation---->rising temperatures. As you can see, this type of feedback can be very important to pay attention to when a scientist looks at Global Warmings.

A negative feedback can be looked at like Earth's checks and balances. An example of a negative feedback would be rising temperatures---->ice melting--->more area for vegetation---->vegetation takes CO2 out of atmosphere---->temperatures lower. Another negative feedback would be rising temperatures---->Earth emits more radiation (by definition)---->temperatures moderate.

It does not take a scientist to take the above examples, compare them, and realize that they are interrelated. So the question is, which one wins? That is, if the positive feedbacks prevail, then Global Warming is like a runaway train that is difficult to slow down. If the negative feedbacks win, then it goes to show that Earth acts like a living organism in itself, constantly checking in on itself and correcting what needs to be corrected.

I can hear the skeptics now. "See, Mr. Shaun, the Global Warming argument is way too complex to form a single conclusion." And once again I will prevent to you our only current home, Earth. It is a lovely place that we are currently performing an unchecked experiment. Plus, I ask the skeptics, do you enjoy living in dirty cities and breathing dirty air? Why not just clean up the air with solar energy and appease the annoying "Global Warming alarmists"?

More on this tomorrow...


Redding Drying Out

By: shauntanner, 9:20 PM GMT on January 27, 2010

The link to the WunderCast Competition is here.

For the first time this forecasting period, Redding is being allowed to dry out. No rain has fallen and the temperature have almost reached 60 degrees.

And, it's official. Consensus is now in first place overall for the contest. Although if weatherguy continues to target Redding, he might take over first place quickly.

I thought I would take a moment to feature one of my favorite webcams here on the site. My family enjoys going up to Lake Tahoe several times a year, and the webcam by muckfish gives a good indication on what the weather is currently like. I enjoy the webcam because it overlooks Lake Tahoe and you can really see when it is snowing hard or the wind is picking up. Look at the video here to see what I mean.

That begs the question, what is your favorite webcam?


WunderCast: KRDD Second Week

By: shauntanner, 6:11 PM GMT on January 26, 2010

The link to the WunderCast Competition is here.

Well, the second week of forecasting for KRDD is underway and we are officially halfway through the competition. So, the halfway point leader is beell, and he is the only competitor who is beating consensus. Consensus is once again doing well in KRDD, with only 5 people beating it.

So, let's finish up KRDD strong. Measurable precipitation has already fallen on the airport today, so if you didn't forecast rain, shame on you! With overcast skies and a weak January sun, expect only minimal daytime warming on Tuesday.

California will get a break from the recent wet weather that has brought both good news and bad news to the state. The good news is that many areas are well above average for precipitation this time of year. The bad news is that it has caused damaged and even some deaths. On Friday, a large Maple tree collapsed on a truck parked outside a San Jose home, killing a toddler and hurting his parents. Upon inspection, the tree was rotted inside and most likely collapsed when the soil around it became saturated from the downpours the city has experienced the last week. So, the ground should dry out over the next week as a ridge of high pressure builds over the West Coast.


Did Somebody Forget To Build The Ark?

By: shauntanner, 6:42 PM GMT on January 22, 2010

Being an all-knowing meteorologist here at the Weather Underground, I get asked a lot of weather-related questions. This is especially true when California is getting pounded by storm after storm after storm...after...storm. Usually, the questions are in the form of "when will it stop raining?" You see, us Californians are a picky bunch. Many of us live here specifically for the weather, so it is logical that when it rains for more than 2 straight hours some people get a little antsy. Will it ever stop raining? What if my pet poodle will float away? Okay, so that is a tiny bit of hyperbole, but a co-worker asked me when it would stop raining the other day. My response was, "after 40 days and 40 nights."

Truth is, this rain is good...really good. The state has been on the verge of a monstrously bad drought for the past few years (Figure 1) and the more rain that falls, the better. Better yet, the more snow that falls in the mountains, the better. That water will eventually melt, flow down the slopes of the Sierra Nevadas and into the reservoirs that store the water that people drink, and more importantly, waters the crops that most of America eats. Yes, this is why people in the East should care about drought in the West just as much as the people living here. The crops in the Central Valley feed much of the country, and drought there affects the whole country, like it or not. So, let's hope it rains for many more days (maybe not 40 days and 40 nights).

The snow depths throughout the Sierra Nevadas are showing healthy, but not spectacular numbers. They range from 33 inches to over 100 inches in the highest locations, with 51 inches on the ground in Tahoe City.

Precipitation averages currently vary wildly with region. For instance, KCQT (Downtown Los Angeles) is close to double its to date average at 9.34 inches, and KSAN (San Diego) is also above its to date average at 5.38 inches since July 1st. Likewise above average is San Jose at 8.82 inches, SFO Airport at 11.34 inches, and Fresno at 5.96 inches, among others.

Farther to the east, Phoenix recorded 1.33 inches just yesterday, making up the bulk of its year to date number of 2.21 inches. This is important to note because most of KPHX's precipitation comes in Summer.

I know what you are thinking..."but, Mr. Meteorologist, what about the mudslides in Southern California and the flooding wherever else?" Well, having family members in potentially "mudslidy" places, I am concerned about it as well. Heck, I had to once again pump out my backyard because the ever-expanding pool of water was creeping toward my backdoor. Poor me! But these dangers occur ever year and so far the mountains and hills have largely held. As long as the experts and residents stay vigilant, the good far outweighs the bad at this point. And just to prove I acknowledge some damage that has been done, I have attached some WunderPhotos taken during the storm.

When Will It Stop?
If you look at the current radar map (Figure 2) you will most likely see that California and the rest of the hard-hit West is experiencing mostly showery activity so far. So, if you lost your toy poodle, you can go look for it now. The good news is that this showery weather will decrease throughout the day on Saturday. California will be on the backside of a very large trough of low pressure (Figure 3) with the most active weather shifting to the Plains. The even better news is that more rain is on the way!

Late Sunday, another powerful Pacific storm will slam into the Northwest coast, north of where this week's weather punished the coat (Figure 4). You can see this next storm lined up in the Pacific in the most recent satellite image. Take a look!

Figure 1. Drought Monitor for January 19, 2010.

Figure 2. Current U.S. Radar Map

Figure 3. 500 mb analysis for Saturday.

Figure 4.

Updated: 7:29 PM GMT on January 22, 2010


WunderCast: Wet And Wild In KRDD And California Weather

By: shauntanner, 6:17 PM GMT on January 21, 2010

The link for the WunderCast Competition is here.

Well, I am back from the AMS conference after a little bit of a delay getting into SFO Airport due to the bad weather back here in California. But the good news is that I didn't have anybody sitting next to me on the airplane, so...more leg room for me!

Redding has been exciting if only for the amount of precipitation that has fallen. So far, 2.79 inches of rain has fallen on the airport, boosting the precipitation to date from 56% of normal to 72% or normal. Good thing, but still a long way to go to get the regional and statewide areas out of the drought that the area is threatened with.

It has already rained in Redding today and I am betting most of you predicted this anyway, so it will most likely all be a wash (both literally and figuratively). Temperatures have been mostly flat but expect a bit of warming as the day progresses.

Major Storms Strike California

The parade of storms that have slammed into the state over the past week has shifted to the south today. I was standing in my house the other day installing some recessed lighting (not the best thing to do during a lightning storm), when a lightning bolt struck probably a few blocks away. I initially thought the spark of light was from saw I was holding, but was quickly corrected when the large boom shook the house. This is not typical weather for California, but the state is being greeted with ample lightning, tons of rain, and even a few Tornado Warnings. Being the family meteorologist, my sister called me in a frantic yesterday when a Tornado Warning was posted for Santa Clara County. I had to reassure here that the storm cell the NWS was tracking was just to the south. You see, us here in California are not used to the sky lighting up with electricity.

As I said, the very active weather has shifted to the south. One look at the jet stream map (Figure 1) will tell you why. The jet stream has shifted well to the south, with aim directly at Los Angeles and San Diego. This has translated to a rainbow of severe weather alerts (Figure 2) including High Wind Warnings, Flood Watches, and even Winter Storm Warnings. With the amount of red ink on the San Diego forecast page, you would think somebody got shot. But, no, just warning people in the area.

I love this type of weather.

Figure 1. Jet stream map for January 21st.

Figure 2. Southwest severe weather alerts.

Updated: 4:43 PM GMT on January 22, 2010


WunderCast: Wrapping Up KBTV

By: shauntanner, 6:44 PM GMT on January 15, 2010

Sorry for the late update. I am at the AMS conference in Atlanta and just got a chance to check on the competition. Congratulations to all and let's move on to Redding.


The link for WunderCast is here.

I want all of you to give a warm, hearty goodbye kiss to Burlington and its chilly airport, KBTV. I hope you all have learned something by forecasting for this Northeastern city and I believe it has been a success. I am glad I picked it and I hope Redding, CA will be just as good.

Two people have scrambled up the rankings to top consensus in the latest scores. Can they hold on one more day to beat this scoring beast? Only time shall tell.

The overcast skies over Burlington has really hampered both radiational cooling before the sun came up and daytime heating after the sun peaked over the horizon. Thus, we have mainly flat temperatures that might bust a lot of temperatures. I can feel the tension and bragging rights in the air. Can you feel it?

As if the atmosphere knew we are coming to California next week, a major weather pattern shift is set for the West Coast. This will mean very much-needed precipitation for the Golden State and the NWS has issued a Special Weather Statement to handle this change.

Watch the wind when making your forecast for Tuesday. And also know where KRDD is, it could make a huge difference.

Updated: 6:41 PM GMT on January 18, 2010


WunderCast: Consensus Beating Everyone

By: shauntanner, 5:39 PM GMT on January 14, 2010

The link to WunderCast is here.

Well, it's official. Consensus is now in first place in the contest. Usually, beating consensus would be considered good. But what happens when consensus beats everyone? Is that good or bad? The reason consensus is winning is because it is correctly hedging its own bets on the precipitation field. What this means is that enough participants are hedging their bets to push the consensus value below the 100% and above the 0% that most people are doing. Thus, it doesn't get dinged the full points when it does or doesn't precipitate while other "smart" competitors get dinged the full amount because they chose not to hedge. I find it fairly interesting what is going on. Consensus has fairly large lead so we'll see if anybody can catch it.

The warmup that we all expected has arrived today with a look at the hourly temperatures. The national temperature map (Figure 1) shows a vastly different map than just a week ago when the historical Arctic outbreak was underway. But note that Burlington is still in some of the coldest air in the country. The chance of snow comes back tomorrow, but only at a low percentage.

I am glad I chose a California city for the second city in the competition. It turns out there is expected to be a parade of storms into the West Coast for pretty much the entirety of next week. Don't believe me? Just look at the Special Weather Statement the NWS has already posted. When a NWS office in California issues a Special Weather Statement, pay attention. Anyway...Redding (KRDD) starts Tuesday!

Figure 1. National temperature map.


WunderCast: Consensus Doing Well

By: shauntanner, 5:54 PM GMT on January 13, 2010

The link for the WunderCast Competition is here.

I find this version of the WunderCast Competition the most compelling yet. First, only two people are beating consensus at the moment. This means that consensus is doing quite well. As can be expected, forecasts are considerably better when you have an array of people collaborating.

Second is the precipitation in Burlington. Prior to this competition and throughout the previous competitions, the biggest complaint was with the precipitation field. The complaints said that the probability of precipitation aspect of the competition was to easy. Most people would either put 100% or 0% and get all of none of the points. In other words, nobody ever chose anything in between.

Now, look at what is happening. Suddenly, we are in a town where we have had some very hard days to forecast in terms of precipitation. On those days, those who chose to hedge their bets have come out smelling like a rose. Also, even the top performers have made mistakes on precipitation forecasting. So, in all, Burlington has been a success in that it has been very hard to forecast for.

Temperatures dipped below zero this morning if you look at the hourly reports. It is still cool there, so we will see how much it warms up. The "warm" air is still farther to the south so I doubt it will show up before the end of the day.

No measurable precipitation yet though.


WunderCast and Pakistan Daily.....What?

By: shauntanner, 11:21 PM GMT on January 12, 2010

Let me start where I always should start, but putting the link to the WunderCast Competition, here, and here (http://www.wunderground.com/wundercast).

Unofficially, it precipitated in Burlington today! You can see the hourly temperatures by going here. Note the measurable precipitation between noon and 1 p.m. So, we'll wait for the official climate report to come out, but for now it looks as though it will verify. In addition, it looks like the temperatures dropped to the low 10's this morning, which is still slightly above average for the morning low.

The cold pool of air will finally pull out of the Northeast Wednesday and into Thursday, leaving Wednesday as the "last" cold day of this forecast period. So, the question will be, how good is your transition forecasting? That is, there will be a considerable warmup on Thursday (heck, it might almost be above freezing, exciting!) and forecasting-wise transition periods are traditionally hard to forecast. Models sometimes over- or underestimate transition periods. I am interested to see how people handle this situation.

---------SARCASM ALERT-------

If you may or may not remember, the Norwegian sky lit up early last month with a wild-looking spiral that lasted several minutes and had many people wondering when the Aliens were going to come and make us into their slaves. The spiral looked like this and you can see it spinning in various YouTube videos like this. While this spiral was very beautiful and mysterious, the real cause was far from anything otherworldly. It turns out this was a failed Russian missile launch that Russia admitted to soon afterward. Still, it was stunning.

I thought the incident was old news until a co-worker passed this article that states, no, in fact the United States was the cause of this spiral. Apparently, what really happened according to the Pakistan Daily was the United States fired a high-energy bean into the sky from its "High Frequency Active Auroral Research Program." This beam, in turn, caused tremendous disturbances in the lower atmosphere and created the most recent Arctic air outbreak in the Northern Hemisphere. Forget the most obvious and reality-driven reasons like southern jet stream penetration and the fact that the Northern Hemisphere is in winter. No, instead, the real reason is the United States shot up a high-energy beam into the exosphere and it somehow created a well-organized spiral of light to occur in Norway that, in turn, caused temperatures to plummet throughout the Northern Hemisphere. What's more, ignore the fact that Russia admitted to the spiral as being a failed missile launch. Apparently, the United States has naked pictures of Russia and decided to force it to admit to the spiral as being their own.


WunderCast: Fourth Day of KBTV Underway

By: shauntanner, 5:34 PM GMT on January 08, 2010

Well, I found out a way to get more people to comment on this blog and WunderCast. All I have to do is update my blog late, then I get all kinds of speculation comments. I like it!

As I have stated in the official rules, I am bound to record the data only from the official climate reports. Thus, some of you have noted that the climate report did record 0.1 inches of snow fell yesterday. However, for whatever reason (station melter not working, bad reporting, etc.), only a Trace of precipitation was reported. Thus, the official recording for precipitation yesterday is "0". Perhaps that 0.1 inches of snow melted to a trace of precipitation. It is entirely possible.

Temperatures so far today are mainly flat, but much cooler than they have been this past week. Also, once again, there has been several reports of light snow (remember the "-SN" we talked about yesterday) so let's see what that melts down to.

The second and last week of Burlington is next week, Tuesday through Friday, so do not forget to make your forecasts on Monday sometime. The middle of next week looks to be interesting as another blast of cold, Arctic air make skirt New England from the north.

Have a good weekend everyone.

Updated: 5:34 PM GMT on January 08, 2010


WunderCast: Can You Feel The Chill?

By: shauntanner, 5:40 PM GMT on January 07, 2010

The second day of the WunderCast competition is complete and you can see the ongoing results here. It is also not too late to register if you want to join in on the fun.

Well, I am happy to see that I rose in the rankings overnight. Consensus is still in a strong position with only 3 people scoring better than it.

For those of you hoping for a measurable amount of precipitation, you barely missed out yesterday. Light snow did fall yesterday, but not enough to squeeze out a measurable amount. Don't believe me? Just look at the proof. If you have the full METAR option turned on (at the bottom of the page), then you will see multiple METARs with the item "-SN". This decodes to "light snow", with the "SN" meaning snow and the "-" meaning light. Further, on those same METARs you will see "P0000". This is the precipitation indicator where "P" means "precipitation." The "0000" means 0.00 inches of precipitation fell. In other words, some precipitation fell, but not enough to trip the 0.01 inch precipitation bucket. Thus, a measurable amount of precipitation did NOT fall yesterday.

If you look at the METAR history for today you will see the same thing has happened today. There has been several observations with a trace of snow. Let's see if any more gets squeaked out today.

It looks like the extremely cold days will not be forecast competition days as the cold air will hold off until the weekend. Nonetheless, Friday looks to be another cold day as the minimum temperature may be somewhat lower than it has been the last couple of days.

You might want to look carefully at the snow chances for tomorrow. The hourly forecast shows a slightly elevated probability of precipitation on Friday. This as the main cold pool along with main low pressure system enters the Northeast on its approach to the weekend.

What will your forecast be?


WunderCast Day 1 Complete

By: shauntanner, 6:50 PM GMT on January 06, 2010

The first day of the WunderCast competition is complete and only one person scored better than the consensus with a few people scoring just as good. This means that the consensus value was really good for the first day, which should be expected. The more heads you have to make a forecast, the better the forecast usually is.

Another chilly day is happening right now at the airport there in Burlington, VT. Temperatures have been pretty much flat to 1 p.m. with only a trace of snow. Just a reminder, measurable precipitation has to fall in order for the it to count as official precipitation in the contest. Thus far, no measurable precipitation has fallen at the airport today, so it will not be counted. Wind has picked up from the northwest, which is not the correct direction you want the wind to blow if you are looking for a warm-up.

The models continue to show little relief to the frigid temperatures in Burlington for the next several days. This should be no surprise when you look at Figure 1. If you want to further astound yourself, go to the models and look at the 850 mb temperatures on Saturday. You will see extremely cold temperatures as far south as the Gulf Coast and will threaten crops throughout the Southeast and in Florida.

The hourly forecast shows flat temperatuers once again, but the truly frigid air will remain to the west in the Plains and Mississippi Valley for another day. The scary chance of snow will remain, so take a risk as you may.

Figure 1. 850 mb temperatures for Thursday.


WunderCast Is Underway

By: shauntanner, 7:17 PM GMT on January 05, 2010

Well, for those of you who have registered for the WunderCast competition but did not make your forecasts for today...WAKE UP!

If you forgot to register for WunderCast, you can still do so by going here. That is also the link to see the current standings as the competition goes on.

The competition is underway with Day 1 in Burlington, Vermont (KBTV). By monitoring the hourly temperatures, you can see that it is chilly at the airport today with a low of 15 degrees and a high of 21 degrees by 2:00 p.m. Tuesday. The snow forecast has already been confirmed, however, as it has indeed snowed.

What is tomorrow expected to bring?

Well, with the cold outbreak in the eastern half of the country ongoing, you can expect more cold temperatures for Burlington. One look at the 850 mb temperatures for Wednesday (Figure 1) shows that cold air will remain entrenched over the East, with the most significant outbreak in the Plains and Rockies.

Actually, the most difficult part about Wednesday's forecast will be the precipitation. The NWS forecast of 30% chance of precipitation is not much help, and when you have cold air over an area for an extended amount of time, it is common to squeeze out just enough snow or other precipitation to tip the bucket. And a tipped bucket is all you need to spoil your forecast.

The hourly forecast is not much help either as it shows basically stagnant temperatures with a 30-40% chance of snow throughout the day. My bones tell me that the chance of precipitation should be higher.

Figure 1. 850 mb temperatures for Wednesday.


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Wunderground Meteorologist Shaun Tanner

About shauntanner

Shaun Tanner has been a meteorologist at Weather Underground since 2004.

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