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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Thanks. I'm glad you like it ... actually a bit lost for words, never been compared to Clapton before but I'll take it.
Magnitude-6.5 earthquake shakes southern Mexico
The Associated Press - 20 minutes ago
MEXICO CITY (AP) — A magnitude-6.5 earthquake shook a wide swath of southern and central Mexico on Thursday, prompting people to flee into the streets in the country's capital. The epicenter was located near the town of Las Chiapas and about 370 miles southeast of Mexico City.
The temblor was felt strongly in Chiapas, a state bordering Guatemala.
There were no initial reports of damage or injuries.
Copyright © 2011 The Associated Press. All rights reserved.
I wish Ike had more of a lasting impact in the form of building codes and power line maintenance. Sadly, building codes haven't changed, and power line maintenance is still abysmal.
Some examples:
When I built my house, I had the builder install steel brackets connecting the frame and the roof, to help keep the roof solid - I had to press pretty hard to get that (its beyond code here in TX).
In an area with new commercial construction, overhead power lines cross a parking lot to attach to a restaurant. Directly underneath one of the distribution lines, the landscapers planted a line of Live Oak and Lobolly Pine trees... Yeah, I can't possibly see what will happen in a few years, when those trees start interfering with the power lines.
In a developing area, a set of power lines is set up, with transformers, along the side of the road. Right next to the power lines (maybe 2 feet away, if that), is a stand of Lobolly Pine trees that are easily 50 feet tall. In a moderate thunderstorm a few months back (it wasn't even close severe, since it went right over my house), one of those trees (that was hit by bark beetles) broke halfway up the trunk, and the branches/top half of the trunk landed on the power line. If there was proper distance from the power lines, the tree branches would have not hit the lines, causing the short. But Centerpoint Energy (who was blasted for not maintaining the lines prior to Ike), didn't even try. As a note, the power lines were installed after Ike.
All powerlines along highways and FM roads need to be underground, in fact along the gulf coast they all need to be underground but cost is the issue.
nop that would not be a good be come we could see under grund flooding from storms or high sea
I am in full agreement.
IMO, if cost is such an issue, when new lines are put in, put them underground. As lines are replaced or repaired due to age, they should be placed underground. There are some areas of town (like Westheimer) where the aboveground lines are disgusting to see, but placing them underground is nigh impossible due to the entire roadside being solid concrete/asphalt. (of course, in the case of Westheimer, you would need to do a lot more than bury power lines to improve the look of the road)
Power lines, when placed underground, are located within waterproof pipes, to prevent flooding issues. I have underground lines on the first 2 levels out from my house (the drop line, and its street-level distribution line are underground, and I *think* the subdivision-level distribution line is also underground). The drop line to my house is 36" underground, which is right around the *average* water table. The power line itself is placed within a 2" waterproof pipeline (forgot the name of the material) that both prevents accidental cuts, and also prevents water intrusion. The biggest water-related issue with underground lines is that of washouts, but if you get a washout 3 feet down anywhere away from the exact coast... you have bigger issues.
Interesting. After Andrew, roof strapping (aka hurricane strapping) became a permanent staple in the Florida Building Codes. Over the years, with each building code revision, the number and size of the straps have increase greatly. Now, you can't even re-roof an older home without meeting current strapping requirements. As for electrical, many of the older Florida homes have above ground power lines running thru the air but most newer homes and businesses have gone to underground service. We had the choice when building our house in 2008 of either above or below ground because in rural areas there are no restrictions. We chose to spend the extra $700 to run the service underground so as to avoid the common problem during storms of the electrical service being ripped off the side of the house (thus causing alot of damage internally as well). In deed restricted and newer communities you can only choose underground but the service is already there as part of the initial subdivision development plan.
I don't understand why Texas wouldn't at least implement coastal building codes with similar requirements in light of Ike's extensive destruction.
14-20 NS
7-12 H
3-6 MH
1-3 cat5s
Shouldn't all coastal area's of CONUS have the same building codes???
Nice one Nea. A similar analogy is complaining about those pesky stop signs. "The elites in Washington have no right to tell ME when to stop"
In terms of regulations, Texas is one of the most backwards states in the country.
My wife and I are very lucky with our house, as we had it built, and the builder (D.R. Horton) actually went above and beyond code in many parts. For example - instead of 2x4s in load bearing areas, they use 2x6, if not 2x8. They added extra bracing in the roof at no charge (but at my insistence). We are an extra foot above street level, beyond what code required (it put the house itself above the 500 yr flood plain, but most of the property is within the 500yr flood plain). Also, they used shatter-resistant double-paned windows, both for insulation, and for protection against flying debris. They aren't "storm windows" that can take a 2x4 end-on at 100mph, but they can take a solid hit without shattering - and if they shatter, its not knife-like shards. They also used termite protection on the frame itself, and used higher strength concrete than the house (and building codes) require.
One would think, but it is a state-level issue.
If you compare building codes across the gulf coast and southeast (from NC down), you will find that TX has some of the most lenient codes out there.
Link
Many of them don't. And while coastal sections of counties should have straps, once you get more than about 30 miles inland, they don't.
Yes but we were specifically discussing Texas. I think it goes without saying that all coastal areas should have the most stringent building codes in place. Why some don't is likely due to the fact that it will increase the cost of building.
Inversion layers creating strong caps suck.
NOAA RUC soundings for Houston IAH, Houston HOU, College Station (CLL), and Conroe (CXO)
Tsunami height is expected to be up to 2 meters. Caution advised.
Tsunami height is expected to be about 0.5 meters. Attention advised.
******* Earthquake Information ********
Occurred at 23:32 JST 07 Apr 2011
Region name MIYAGI-KEN OKI
Latitude 38.2N
Longitude 142.0E
Depth about 40 km
Magnitude 7.4
Link
Taz, they do take that into account when running service underground.
Date-Time
Thursday, April 07, 2011 at 14:32:41 UTC
Thursday, April 07, 2011 at 11:32:41 PM at epicenter
Location 38.253°N, 141.640°E
Depth 25.6 km (15.9 miles)
Region NEAR THE EAST COAST OF HONSHU, JAPAN
Distances
66 km (41 miles) E (90°) from Sendai, Honshu, Japan
118 km (73 miles) ENE (60°) from Fukushima, Honshu, Japan
147 km (91 miles) NNE (26°) from Iwaki, Honshu, Japan
333 km (207 miles) NNE (30°) from TOKYO, Japan
Location Uncertainty horizontal +/- 13.1 km (8.1 miles); depth +/- 7.2 km (4.5 miles)
Parameters NST=426, Nph=427, Dmin=358.4 km, Rmss=0.75 sec, Gp= 32°,
M-type=regional moment magnitude (Mw), Version=B
Source
U.S. Geological Survey, National Earthquake Information Center:
World Data Center for Seismology, Denver
Event ID usc0002ksa
Tsunami Warning/Advisory
Issued at 23:34 JST 07 Apr 2011
******************Headline******************
Tsunami Warnings (Tsunami) have been issued for the following coastal regions of Japan:
MIYAGI PREF.
Evacuate immediately to safe place away from the shore in the above coastal regions.
Tsunami advisories are currently in effect in other coastal regions of Japan.
There would have been only a comparative handful of homes on river/beachfront property without heavy government intervention.
Prior to the early 1960s, folks couldn't get business loans to build nor mortgages to buy homes on river/beachfront property. Ya had to use your own*money cuz insurance companies would not accept the risk of insuring those properties because reinsurance companies would not accept the risk.
Then Congress stepped in with FEMA and its flood insurance programs though which the US taxpayer was made into the insurer-of-last-resort. ie Insurance companies could pass the majority of the risk onto the federal government while making money selling the policies.
Banks could get their loans&mortgages insured. And the coastal building boom began.
* Unless you were sufficiently independently wealthy that banks would know that you could easily self-insure the loan/mortgage with your publicly-known-to-be fully owned assets; that you were taking out the loan/mortgage for convenience and the income tax writeoff, and not because you needed the loan/mortgage.
Prior to the federal flood insurance program, beachfront living was for "the fabulously wealthy, movie stars and old money" -- hence the cachet -- the hoi polloi could never afford to move in to "roughen the neighborhood".
Wouldn't standardized building codes make it easier for builders to go by. Also, why is it only 30miles? shouldn't it be much further inland than that?
Easier, yes. More expensive, yes.
In TX, many of the regulatory agencies are staffed by lobbyists pulled from the ranks of the companies they are regulating. This is especially prevalent in our current governor's staff, and extremely so in the case of insurance.
this is not good
can someone keep up with the tsu warnings please
7.4 2011/04/07 14:32:42 38.253 141.640 25.6 NEAR THE EAST COAST OF HONSHU, JAPAN
7.4 2011/04/07 14:32:00 38.200 142.000 40.0 NEAR THE EAST COAST OF HONSHU, JAPAN
Yep. The lat/lon is less than half a degree off, and they were 42 seconds apart. I think one is a preliminary location, and the second one is more refined.
JMA has three "issued" times for the same "occurred" time.
Issued at Occurred at Region Name Magnitude Maximum seismic intensity
(JMA Seismic Intensity)
23:53 JST 07 Apr 2011 23:49 JST 07 Apr 2011 Miyagi-ken Oki M4.7 3
23:46 JST 07 Apr 2011 23:32 JST 07 Apr 2011 Miyagi-ken Oki M7.4 6+
23:37 JST 07 Apr 2011 23:32 JST 07 Apr 2011 Miyagi-ken Oki M7.4 6+
23:36 JST 07 Apr 2011 23:32 JST 07 Apr 2011 Miyagi-ken Oki M7.4 6+
Its going to be a long time before its even remotely stable over there.
- at work and trying to keep up -
do we need to worry about tsunamis again?
and what about fukupshima?
It sounds like you were able to get some solid upgrades in there. DR Horton had some run ins with the chinese drywall here in Florida. Not sure if it affected other states. The vast majority of homes here are concrete block, but they build the 2nd story wood frame which is a little unnerving. They build a nice looking home though and it sounds like yours turned out great.
Well i am sure if there is a tsunami generated, the the system that failed due to the extream height of the major tsunami will hold up well against smaller tsunami's
There is a 50/50 chance of an active year at this point, let's wait and see what the atmospheric pattern is on June 1 before making any hasty predictions. Furthermore, just like all coastal Americans should be, Insurance companies should also be ready every year in the event a hurricane visits your insured homes.
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