Early 2011 Atlantic Hurricane Season Forecasts
Hi everybody, this is Dr. Rob Carver filling in for Dr. Masters.
A continuation of the pattern of much above-average Atlantic hurricane activity we've seen since 1995 is on tap for 2011, according to the latest seasonal forecast issued April 6 by Dr. Phil Klotzbach and Dr. Bill Gray of Colorado State University (CSU). They are calling for 16 named storms, 9 hurricanes, and 5 intense hurricanes. An average season has 10 named storms, 6 hurricanes, and 2 intense hurricanes. The new forecast is nearly identical to their forecast made in December, which called for 17 named storms, 9 hurricanes, and 5 intense hurricanes. Only six seasons since 1851 have had as many as 17 named storms; 19 seasons have had 9 or more hurricanes. The 2011 forecast calls for a much above-average chance of a major hurricane hitting the U.S., both along the East Coast (48% chance, 31% chance is average) and the Gulf Coast (47% chance, 30% chance is average). The Caribbean is forecast to have a 61% chance of seeing at least one major hurricane (42% is average.) Five years with similar pre-season November atmospheric and oceanic conditions were selected as "analogue" years that the 2011 hurricane season may resemble: 2008, 1999, 1996, 1955, and 2006. The first four years listed all had neutral to La Niña SST's during hurricane season, while 2006 had El Niño SST's. The average activity for these years was 12.6 named storms, 7.8 hurricanes, and 4.8 major hurricanes.
This year, the forecasters have introduced a new statistical model for their April forecasts. There are four components in this model:
1. Average sea-level pressure in March around the Azores in the subtropical Atlantic.
2. The average of January through March sea-surface temperatures (SST's) in the tropical Atlantic off the coast of Africa.
3. Average sea-level pressure in February and March for the southern tropical Pacific ocean west of South America.
4. Forecasts of September's SST in the tropical Pacific using a dynamical model from the European Centre for Medium-Range Weather Forecasts (ECMWF)
The first two components are loosely linked together. Statistical studies have shown that a weaker subtropical high near the Azores, combined with warmer SST's off the coast of Africa in March are associated with weak winds near the surface and aloft from August to October. This decrease in wind speeds reduces wind shear which can disrupt forming storms. These March conditions also are associated with warmer SST's in August to October, which is also favorable for more tropical storms. For this forecast, the first component is strongly favorable for increased hurricane activity, while the second component is weakly negative.
The last two components represent the changes in sea-surface temperature and sea-level pressure that are the El Niño-Southern Oscillation (ENSO). Briefly speaking, El Niño conditions (warm sea-surface temperatures) are not favorable for Atlantic hurricanes. For more info on ENSO and hurricanes, Jeff has this article.
Using the ECMWF model as guidance (see Figure 1), the CSU group believes that SST's in the tropical Pacific will be neutral (less than 0.5°C from normal). This would have a small negative effect on hurricane activity. However, the tropical Pacific sea-level pressure shows that the atmosphere looks like a La Niña event is still going on. This is strongly favorable for Atlantic hurricane activity in the CSU group's model.
Figure 1. Forecasts of El Niño conditions by 20 computer models, made in March 2011. The ECMWF forecast used by the CSU group is represented by the dark orange square. The forecasts for August-September-October (ASO) show that 5 models predict El Niño conditions, 7 predict neutral conditions, and 5 predict a weak to moderate La Niña. El Niño conditions are defined as occurring when sea surface temperatures in the Equatorial Pacific off the coast of South America ( the "Niño 3.4 region) rise to 0.5°C above average (top red line). La Niña conditions occur when SSTs in this region fall to 0.5°C below average. Image credit: Columbia University.
How accurate are the April forecasts? While the formulas used by CSU do well in making hindcasts--correctly modeling the behavior of past hurricane seasons--their April hurricane season forecasts have had no skill in predicting the future. This year's April forecast is using a new system and has not yet produced a verified forecast. The scheme used in the past three years successfully predicted active hurricane seasons for 2008 and 2010, but failed to properly predict the relatively quiet 2009 hurricane season. A different formula was used prior to 2008, and the April forecasts using that formula showed no skill over a simple forecast using climatology. CSU maintains an Excel spreadsheet of their forecast errors ( expressed as a mathematical correlation coefficient, where positive means a skilled forecast, and negative means they did worse than climatology) for their their April forecasts. For now, these April forecasts should simply be viewed as an interesting research effort that has the potential to make skillful forecasts. The next CSU forecast, due by June 1, is the one worth paying attention to. Their early June forecasts have shown considerable skill over the years.
Figure 2. Accuracy of long-range forecasts of Atlantic hurricane season activity performed by Phil Klotzbach and Bill Gray of Colorado State University (colored squares) and Tropical Storm Risk, Inc. (colored lines). The CSU team's April forecast skill is not plotted, but is less than zero. The skill is measured by the Mean Square Skill Score (MSSS), which looks at the error and squares it, then compares the percent improvement the forecast has over a climatological forecast of 10 named storms, 6 hurricanes, and 2 intense hurricanes. TS=Tropical Storms, H= Hurricanes, IH=Intense Hurricanes, ACE=Accumulated Cyclone Energy, NTC=Net Tropical Cyclone Activity. Image credit: TSR.
2011 Atlantic hurricane season forecast from Tropical Storm Risk, Inc.
The British private forecasting firm Tropical Storm Risk, Inc. (TSR), issued their 2011 Atlantic hurricane season forecast on April 5. They are also calling for a very active year: 14. 2 named storms, 7.5 hurricanes, and 3.6 intense hurricanes. We would round that to 14 named storms, 8 hurricanes, and 4 intense hurricanes. This compares to their forecast issued in December of 15.6 named storms, 8.4 hurricanes, and intense hurricanes. TSR predicts a 55% chance of an above-average hurricane season, 28% chance of a near-normal season, and only a 17% chance of a below normal season. TSR bases their April forecast on predictions that sea surface temperatures this fall in the tropical Atlantic will be above about 0.08°C above average, and trade wind speeds will be about 0.2 m/s slower than average. The decrease in the trade wind speeds is favorable for enhanced hurricane activity, while the forecast SST's are expected to be neutral for hurricane activity.
TSR puts their skill level right next to the forecast numbers: 13% skill above chance at forecasting the number of named storms, 11% skill for hurricanes, and 10% skill for intense hurricanes. That's not much skill, and really, we have to wait until the June 1 forecasts by CSU, NOAA, and TSR to get a forecast with reasonable skill.
Rob's critiques of the April forecasts
I have to note that Jeff and I wrote this article together. He wrote the general framework before the forecasts were issued, while I wrote the details based on the actual forecasts. So the preceding text is a joint production. However, I have a few observations to make that are my responsibility alone.
First, I am disappointed that the CSU group has changed forecast models only after three seasonal forecasts. This makes it very difficult to assess the skill of the current forecast using past performance. This is very important for forecast users, and they do it everyday. For example, I tend to discount a forecast of rain if it comes from a source that over-forecasts rain (The boy who cried wolf problem).
In the documentation that came with the April forecast, the CSU group argue that the hindcasts show the new forecast model has skill. However, I think hindcasts are a poor substitute for real forecasts in understanding the skill of a statistical forecast model, like that of the CSU's group. As Jeff noted, the previous forecast model did well with the hindcasts and yet had mixed results with the actual forecasts. This does not give me confidence that the new forecast model will be superior to the previous model.
From a philosophical viewpoint, I am inherently cautious about statistical forecast models like the one used by the CSU group. Essentially, they look at what happened in the past and use that to predict the future. However, for making forecasts, we assume that the relationships in space and time between the predictors (such as the average March sea-level pressure around the Azores) and the predictands (Atlantic hurricane activity) does not change as we move forward in time. In a world with climate change, that's a tricky assumption to make.
In any event, it is customary in the meteorological community to continue running older forecast guidance models after the introduction of newer models. This allows forecasters and forecast users to leverage their knowledge of the forecast skill of the older model and gain insight into the forecast skill of the new model. The CSU group really should have included the forecast from the previous statistical forecast system in this forecast.
I am uneasy with some of the methodology choices made in implementing the forecast model. Data for the first three predictors was obtained from the Climate Forecast System Reanalysis (CFSR), NOAA's newest and most advanced reanalysis product. However, CFSR data for 2010 and 2011 has not been released yet, so the CSU group used NCEP/NCAR Reanalysis (NNR), NOAA's first-generation reanalysis, to fill in the gaps. Due to differences in design, resolution, etc., CFSR and NNR can have different depictions of the state of the atmosphere. So using NNR's March 2011 average SLP instead of CFSR's could alter the forecast in unexpected ways. It would be interesting to see how CFSR's 2010-2011 data changes the results.
In any event, we will have to wait and see what the Atlantic hurricane season of 2011 brings.
Reader Comments
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You don't really wanna hear the weather isn't climate talk right now do ya? You guys like saving that one for blizzards and cold snaps, right?
I'm expecting above average rainfall for this month,almost at the average already,it should be double or even triple the monthly average by April 30th.
If you want to look at the climatic avg, t doesn't show any significant trends, unlike Tampa claimed.
Any climatologist worth their salt understands what I said. It's the arctic sea ice extent we're concerned about, which has been steadily declining over recent decades.
Interesting how it differs from the new CFS.
I don't even know what to say.
In any case, the globe is still warming humans are still contributing. Let me know when ya'll find something of interest to suggest other wise.
“The committee should understand that the IPCC presents one version of climate change science generated by an establishment that has evolved to largely reflect a particular point of view…this point of view attempts to dismiss information that questions the belief that greenhouse gases are the dominant cause of observed climate change.”
Link
I'm not going to bother reading through the many hours worth of text, but just looking at some of the graphs, I couldn't help but laugh:
comical at best. It's obvious he took graph charts and then added his own temp scales to the left side because of the different font and color. GEE, I WONDER WHY.
Not only that, but it doesn't even make sense. If you look at the graph and find the 0c anomaly line, its well above all the data. so where did he come up with the average? CLEARLY it was not determined using the data on the graph, or else the lines would reflect that. For all we know, he could of just created that line out of thin air.
How ironic is it that this man is trying to prove scientists are messing with the data, when clearly he is doing exactly that.
I also always find it ironic that people believe in what one website on the internet tells them over what all the scientists say.
Once again, let me know when you deniers can show me the earth is cooling. or how humans have zero effect.
And I'll simply flag your comment for the ad hom.
I'm just trying to point out that this website is clearly altering data. I could honestly care less about your paleoclimate issues, it does nothing to disprove we are presently warming. nothing at all. night
TORNADO WARNING FORT WORTH TX - KFWD 1225 AM CDT MON APR 11 2011
Japan Times
Oh great.. the zingers are back.
Seriously, go back through the blog and compare the zinger posts with the posts by people that are respected and that quote facts (on either side), the worse the argument and the less intelligent the poster, the greater the use of zingers.
I always hear George Costanza's voice after these. "It's a zinger, Jerry. He got with me with the zinger. I was right there, and then he brought out the zinger!"
Jerry: "I do think you're right. You have been zung, George."
George: "Yep, got me with the zinger. What can you do?"
The good news: it was just updated to a 6.6.
The bad news: the quake was actually centered inland roughly midway between Sendai and Tokyo, and located at a fairly shallow 6.2 miles.
According to Kyodo, external power is "no longer available" at the Fukushima plant, so water injection has ceased. Uh-oh...
The good, the bad and the ugly! ;)
Indeed. TEPCO says 220,000 are without power from today's one-month anniversary aftershock. The Japanese Weather Agency--which includes that country's version of the USGS--revised the quake to 7.0 from 7.1 (as opposed to the USGS, which, as I said a bit ago, revised it from 7.1 to 7.0).
Kyodo Article...
Reading between the lines: while the news media have largely packed up and moved on, the situation remains dire. The reactors are more stable than they were a few weeks ago--a very good thing--but workers are still stuck doing nothing more than pouring water on the rods in an attempt to keep them from melting down, the equivalent of holding their fingers in a massive dam to stop a flood. In a recent article, there were admissions that the situation may take months or even years to stabilize enough that cleanup and mitigation efforts can get underway. My favorite quote from that article:
''We are fighting against a monster named nuclear power with human wisdom.'' (Economy, Trade and Industry Minister Banri Kaieda.)
USGS hasn't got it that I could find...short-lived, maybe a 5-6 mag?
someone with better eyes, take a look...
not bad for one just trying to read seismos, tho. It was one hard short-lived jolt, wobbly to begin with then CRACK, then it was all over.
Good morning dayshift.
A very good quote!
This one make you happy?:) Seventeen-hundredths of an inch forecasted...for a boat east of JAX!!!!!!!! LOL!
"We are fighting against a monster named nuclear power with human wisdom." (Economy, Trade and Industry Minister Banri Kaieda.)
coulda /shoulda used more wisdom then greed b/4 this all happen. Wisdom ain't sham-wow when it comes to cleaning up a mess that will exist beyond our lifetimes.
GOOOD MORNING AQUA!!
Zero point flippin' one seven.
Oh yeah, I'm dancing in circles here.
LOL!
I'm sorry:(
There have been 10 so far in less than 3 hours including the first at 6.6.
A total of 9 of these new shocks are almost on top of each other!
It would seem that this new bunch of shocks over the last few days are forming a short line from the coast above the nuclear plant down to the Tokyo bay area, as there has been quite a lot of activity here. this may be a bad sign for the near future and with the Tokyo bay area maybe getting hit soon as well.
The big volcano near Tokyo also might fire up a bit as a consequence of all this activity.
So starting off with a 7.1 that was 4 days ago,there have been in excess of 30 shocks over 4.5 and this is a month after the main one at 9, so things don't seem to be quietening down yet.
Lets see what the experts have to say?
(ignores ike)
hello surfy good to see ya
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