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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Show me the MONEY! :)
I really don't understand that logic.
:(
Mine shows 79deg right now at my house
Dr masters supports Agw, so it would only be logical that the majority of the posters on here would reflect this sentiment.
In any case, would you rather this be a primarily gw denial blog? The earth is obviously warming, all evidence we have indicates it. I don't care if you don't believe scientists, you can find the evidence on your own, just make the trip to the arctic, or Antarctica for yourself. Conduct your own research. Come to realize what thousands of scientists have already realized.
What contribution humans have on this trend is not fully understood. Clearly we have some effect.
Honestly, anyone who can't come to grip with any of these ideas is in flat out denial. I have no idea why you would want a blog where the majority of posters are in denial.
Well, I'm out; I've had enough stunning logic and eloquent writing thrust upon me for one evening. Play nice...
SunlinePR was a students project in high school, to synchronize the taking of sunset digital photos in diferent spots latitudes, (North to south) but at the same longitude (Western coast) and compare the results to see if the photos were alike.... They tried to explain what variable made the photos look diferent...
Go conduct the science yourself then. All scientific evidence points in one direction on the topic of global temperatures. and you have zero evidence that all his evidence is biased. None.
As for humans impact, the extent at which we effect the climate is debatable, but the question of if we effect it is not.
Wow, have people left this blog.....hum... is not totally accurate. Many have left but, many just don't comment anymore that was large contributors of this blog. There are just a few on here that are total Smart Asses that love to just challenge a fight it seems. Most know those i talk of. You can read above and back some to figure one out...........JUST SAYN the truth.
YOU MIGHT WANNA check on your account of the melting of the Antarctic melting.........most sources say its growing. Just another example of ........well you know!
Remember the Hockey Shtick?
The Yamal implosion
Science needs to be sound..... period!
Just sayin, the words don't disappear, nor does the inflection of such words......
Be glad we have that of which helps us clear the vision sometimes..........
The pre-Climategate issue that is the issue
out>>>
Yamal
Think about it ~~~~
Nice straw man you built there. I didn't make a stance on AGW, but brought up the temp record and paleoclimatology issues. Neither of which you decided to mention or talk about. Try again...or not, its your choice.
That low over Hawaii, has been bringing rain to the area for the last 3 days...
Levi...the term "spitting out" is really befitting here..lol....BTW, it's good to see ya on the blog and hope to learn even more from you this season :)
I'm trying to make the point that currently we are warming. You paleoclimatic problems have nothing to do with that, and do nothing to prove we aren't warming.
Calm yourself Tampa, believe me, I've checked. The antarctic hasn't shown much in the way of decreasing sea ice levels, nor in the way of increasing sea ice levels.
Here's a graph regarding antarctic sea ice level anomalies
Notice, not all climate related graphs show warming or vicious hockey stick patterns you are all afraid of.
Another thing to note, presently, antarctic sea ice levels are below average and have been going down for the last year, so don't get so excited.
Thanks :) I'm always happy to be here.
Looks like some rain for us here in the windward islands :D
BTW can you post the precip forecasts for the Atlantic basin TIA.
Sure.
ECMWF:
Japanese:
CFSv2 (a little drier, which is interesting):
Antarctic sea ice is largely irrelevant insofar as impacts to global climate are concerned.
Link not working for me.
sorry fixed it
Hmmm...Removing evidence of the MWP and leading people to believe that the earth is warming so much that it has never been as hot as it will be isn't important to the AGW situation? Manipulating data sets to skew plots of temp trends isn't unacceptable behavior to the GW team huh? Looks to me like southern ice gains more in the winter than gets lost in the summer. Look at all those data points above zero!
On 11.04.2011 at 03:24 GMT+2
Wildfires scorched more than 230,000 acres in Texas on Sunday, roaring through a West Texas town, destroying an estimated 80 homes and buildings and critically injuring a firefighter. The Texas Forest Service reported more than 60,000 acres burned and 40 homes lost in one blaze that raced through West Texas and into the small mountain town of Fort Davis. The fire rushed across 20 miles in 90 minutes. Officials at the scene, however, estimated at least 100,000 acres in two counties had burned from the fire, which continued to grow Sunday evening. "I can only describe it as an ocean of black, with a few islands of yellow," State Representative Pete Gallego said. Flames "licked at the edges" of the town but did not burn their way through its center, sparing more buildings than expected, he said. But 17 to 20 homes were destroyed, and as many as 30 more buildings were burned, he said after visiting the town, including a more than 100-year-old historic wooden ranch home. Residents had worked overnight to save their homes and moved on to help their neighbors, he said. Hot spots still burned along the highway, and a glow from miles away was visible at night, he said.
"Even now, the flames in some places are 15 to 20 feet high," Gallego said. The town was without power Sunday evening. Gallego said many of the residents may not have been insured for fire. Presidio County Emergency Management Coordinator Gary Mitschke said it was the first fire to scare him in 13 years of fighting grass fires. The blaze crossed railroad tracks and state highways as it roared past Fort Davis, he said. Without a change in winds, which were keeping aircraft from helping firefighting efforts, the fire could burn for days or weeks, he said. "Frankly, it moved almost as quick as a truck," Mitschke said. "When you hear the word firestorm, this is what I imagine." A federal emergency management spokesman said a fire grant for the county had been approved Saturday and that the agency stood by to support as needed. Wildfires fed by dry, windy conditions have charred more than 270,000 acres in eight days across Texas, burning homes, killing livestock and drawing in crews and equipment from 25 states. Plants that thrived in wet weather turned to tinder under a cold, dry winter. Weeks of high winds and little moisture have made every spark dangerous. A Texas firefighter was in critical condition with severe burns Sunday afternoon after fighting an estimated 60,000-acre fire in the northern Panhandle.
The cause of the fire was under investigation, but it started in an isolated area near a natural gas plant and a few other industrial sites in an empty town called Masterson, said David Garrett, an emergency management spokesman for Moore County. "Kind of like a wide spot in the road that has a name," Garrett said. "The fire started in open country and stayed in open country." Two nearby communities were considered threatened but were not evacuated late Sunday afternoon, according to the forest service. A Midland County wildfire burned 40 homes and at least 15,000 acres, according to the service. Crews had stopped from crossing a highway a sprawling 71,000-acre fire that killed almost 170 head of cattle in Stonewall County, spokesman Lee McNeely said. Air tankers had dropped 60,000 gallons of retardant to help slow the blaze. Firefighters had most of the day to prepare for a cold front with gusting winds, McNeely said. High winds and dry conditions were expected to persist into the evening across West Texas, the National Weather Service warned. In Oklahoma, where Governor Mary Fallin has extended a 30-day state of emergency she declared on March 11, firefighters and helicopters on Sunday mopped up the smoldering remains of two fires that erupted Saturday. One wildfire in Cleveland in north central Oklahoma charred more than 1,500 acres and forced 350 people to evacuate while another struck near Granite in southwest Oklahoma, said Michelann Ooten, a spokeswoman for the state Office of Emergency Management.
Spain is burning too.
Don't like the data...just throw it out.
Looks like Briffa and Mann and Schmidt have taught you all well!
Unlike your link, my link is up to date and shows that in the last year sea ice has been dropping. Yet your link stops the graph at mid 2010, ironically that's right when my graph begins to plummet.
Coincidence?..
Does not fit the agenda.....or if the glove does not fit you must acquit.
It's in no bodies favor.
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?
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