Early 2011 Atlantic Hurricane Season Forecasts

By: Dr. Jeff Masters , 6:22 AM GMT on April 07, 2011

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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.

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Here's the key with gas. Go to Shell one week, go to Exxon one week, go to Chevron one week. If you spread out with different stations regardless if one is 5 cents cheaper or not you wont have to pay a large one time bill. Your billing periods are spread out this way and it's easier to pay. It works for me.
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183. IKE
$3.75.9/gallon here at my location.


BREAKING
NEWS

Oil crosses $110 a barrel for the first time since September 2008.



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Quoting RastaSteve:
Never said anything will form it's just interesting to see that much moisture bubbling up in the Caribbean in April.
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Quoting IKE:
$4.00 a gallon?

$5.00 a gallon?

  • Oil+0.87Price/barrel$109.70



I know there's been talk of $5/gal gas but IMO that may be a bit of a stretch. $4+ is approaching quickly however. Good thing I only need to fill up once every 3-4 weeks.
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Quoting RastaSteve:


Looks like some rain on a consistant basis maybe setting up cross your fingers. Is it still bone dry there?
Yes it is still very dry out here i am hoping for a early start to the rainy season according to the weather pattern the rain season should start in the 1st week of may . And i doubt we will have significant rain before then
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Quoting IKE:
Paging DestinJeff.....




LOL I think he has these set to reprint every 15 minutes during the season.
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Hi all.

Hmmnnnn. On the power plant front, we may see further damage to buildings that are holding water where water would not normally be expected. That water would have exerted substantial additional forces on side walls when the quake hit.

We may also see damage to some equipment that has been brought in - those 200 foot booms that have been spraying water come to mind.

Fukushima Daiichi is much closer to this quake than the main quake a month ago.

The event everyone was hoping (against established probabilities) would not happen has happened. Let's hope they managed to get past this one without a major deterioration in circumstances.

Those poor people in Miyagi and Fukushima prefectures :(

WTO
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172. IKE
$4.00 a gallon?

$5.00 a gallon?

  • Oil+0.87Price/barrel$109.70

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171. IKE
Paging DestinJeff.....


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All may tropical cyclonesLink
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..........And here we go........
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166. IKE
Quoting jeffs713:
163.

JB isn't with Accuweather.

WCarib isn't a noted hotspot for formation pre-season - most pre-season storms form off the tail end of stalled fronts, IIRC.

Also, where do you see 5-7 degree anomalies in the GOM?

And finally... the atmosphere SUCKS over the GOM for anything. Its all kinds of hostile. Its not just about SSTs.
DOWNCASTER!:)
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163.

JB isn't with Accuweather.

WCarib isn't a noted hotspot for formation pre-season - most pre-season storms form off the tail end of stalled fronts, IIRC.

Also, where do you see 5-7 degree anomalies in the GOM?

And finally... the atmosphere SUCKS over the GOM for anything. Its all kinds of hostile. Its not just about SSTs.
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160.

Looks like an extension of the Columbian heat low, and its WAY too far south for any formation. Also, if you look at the wind barbs at diff levels, it will be wrestling with about 20-25kt of shear. This isn't accounting at all for the fact there is hardly any mid-level vort, the (very) rough 850mb circulation is about 200-300 miles west (the 500mb circ is over Guatemala), and there is no circulation, of any kind (including anticyclones), at the upper levels.

IMO, you're seeing something that isn't there.

[edit: Oh, and its 12 days out, too!]
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The magnitude7.1 earthquake that struck off the northeasternHonshu coast was epicentered
33miles at 91.5degees(E) from the port of Sendai (Miyagi-ken Sendai-shi Miyagino-ku)
66miles at 29.9degrees(NNE) from the FukushimaDaiichi nuclear powerplant.

The lone red dot is centralTokyo.

Interesting coincidence: Sendai's port town and FukushimaDaiichi share the same longitude.
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Quoting sunlinepr:

Good video. You can also get an idea of how accustomed to earthquakes the Japanese are as a society. When they show the video in the office, notice the guy on the far right... HE KEEPS WORKING. That is perseverance!
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Member Since: August 2, 2010 Posts: 21 Comments: 9882
Just what they did not need another big Quake and now this.
Japan lifts tsunami alert, but says power cut at one nuke plant
USA Today - Douglas Stanglin - ‎10 minutes ago‎
Update at 12:01 pm ET: NHK World TV reports that external electrical power supply has been cut in two of the three lines servicing the Ongawa nuclear power plant in the Miyagi prefecture because of the quake.
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Tsunami Warning/Advisory

Issued at 00:55 JST 08 Apr 2011

Tsunami Warnings and/or Advisories have been cancelled.

*******************Text********************
Tsunami Warnings have been cancelled for the following coastal regions of Japan:
MIYAGI PREF.
The above-mentioned Tsunami Warnings/Advisories have been cancelled.

Tsunami Advisories have been cancelled for the following coastal regions of Japan:
IWATE PREF.
FUKUSHIMA PREF.
PACIFIC COAST OF AOMORI PREF.
IBARAKI PREF.
The above-mentioned Tsunami Warnings/Advisories have been cancelled.

*******Tsunami Warning/Advisory now in effect********
No Tsunami Warnings and Advisories are currently in effect.

Member Since: July 15, 2006 Posts: 178 Comments: 56141
Quoting AussieStorm:
Goodnight all. Stay safe. Stay healthy, I'm going to bed, meds are taking effect.
goodnight aussie
Member Since: July 15, 2006 Posts: 178 Comments: 56141
Goodnight all. Stay safe. Stay healthy, I'm going to bed, meds are taking effect.
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Quoting KEEPEROFTHEGATE:
i hate to say this but 7.4 may not be the biggest we have seen there is more than likly a stronger one yet to come
I cannot imagine what the survivors there must be feeling. Mornin Keep.
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Quoting AussieStorm:
It has been revised down to a single 7.1 quake.
ok i stand corrected a 7.1 may not be the biggest to come there may be something much bigger
Member Since: July 15, 2006 Posts: 178 Comments: 56141
Member Since: July 15, 2006 Posts: 178 Comments: 56141
Quoting KEEPEROFTHEGATE:
i hate to say this but 7.4 may not be the biggest we have seen there is more than likly a stronger one yet to come
It has been revised down to a single 7.1 quake.
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i hate to say this but 7.4 may not be the biggest we have seen there is more than likly a stronger one yet to come
Member Since: July 15, 2006 Posts: 178 Comments: 56141
Quoting emcf30:
Biggest wave so far 1 meter

A home has collapsed and an 85y.o woman is trapped under the rubble. All tsunami alerts ans warning have now been lifted.
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Quoting eddy12:
insulation is an issue concrete r factor is close to zero
Oh. (I was thinking of natural stone)
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Biggest wave so far 1 meter
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I was thinking those plant sites were right by the quake, but are farther south a good ways
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Quoting KEEPEROFTHEGATE:
Tsunami Information NUMBER 2
(High Tide Time and Estimated Tsunami Arrival Time at each place)

Issued at 23:35 JST 07 Apr 2011

High Tide Time and Estimated Tsunami Arrival Time at each place
Exercise extreme caution if a tsunami arrives at high tide, as this boosts the height of waves.

Tsunami Forecast Region/
Tsunami Observation Site High Tide Time Estimated Tsunami
Arrival Time

MIYAGI PREF. (*1)
Ishinomaki-shi Ayukawa 05:08 JST 08 Apr 23:40 JST 07 Apr
Sendai-ko 05:13 JST 08 Apr 00:10 JST 08 Apr

PACIFIC COAST OF AOMORI PREF. 00:20 JST 08 Apr
Hachinohe 04:52 JST 08 Apr 00:40 JST 08 Apr
Mutsu-shi Sekinehama 04:50 JST 08 Apr 00:50 JST 08 Apr
Mutsuogawara-ko 04:50 JST 08 Apr 00:30 JST 08 Apr
IWATE PREF. (*1)
Miyako 04:54 JST 08 Apr 00:00 JST 08 Apr
Ofunato 05:01 JST 08 Apr 23:50 JST 07 Apr
Kamaishi 05:03 JST 08 Apr 00:00 JST 08 Apr
Kuji-ko 04:54 JST 08 Apr 00:20 JST 08 Apr
FUKUSHIMA PREF. 23:50 JST 07 Apr
Iwaki-shi Onahama 05:28 JST 08 Apr 00:20 JST 08 Apr
Soma 05:19 JST 08 Apr 00:20 JST 08 Apr
IBARAKI PREF. 00:20 JST 08 Apr
Oarai 05:25 JST 08 Apr 00:30 JST 08 Apr
Kamisu-shi Kashima-ko 05:35 JST 08 Apr 00:30 JST 08 Apr

*1 mark: Arrival of tsunami inferred.

Tsunami Warnings and/or Advisories are in currently effect for the following coastal regions of Japan:

MIYAGI PREF.

PACIFIC COAST OF AOMORI PREF.
IWATE PREF.
FUKUSHIMA PREF.
IBARAKI PREF.
Although there may be slight sea-level changes in coastal regions other than the above, no tsunami damage is expected in those coastal regions.

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
Looks like any tsunami will be at low tide, which is a good thing.
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Tsunami Information NUMBER 2
(High Tide Time and Estimated Tsunami Arrival Time at each place)

Issued at 23:35 JST 07 Apr 2011

High Tide Time and Estimated Tsunami Arrival Time at each place
Exercise extreme caution if a tsunami arrives at high tide, as this boosts the height of waves.

Tsunami Forecast Region/
Tsunami Observation Site High Tide Time Estimated Tsunami
Arrival Time

MIYAGI PREF. (*1)
Ishinomaki-shi Ayukawa 05:08 JST 08 Apr 23:40 JST 07 Apr
Sendai-ko 05:13 JST 08 Apr 00:10 JST 08 Apr

PACIFIC COAST OF AOMORI PREF. 00:20 JST 08 Apr
Hachinohe 04:52 JST 08 Apr 00:40 JST 08 Apr
Mutsu-shi Sekinehama 04:50 JST 08 Apr 00:50 JST 08 Apr
Mutsuogawara-ko 04:50 JST 08 Apr 00:30 JST 08 Apr
IWATE PREF. (*1)
Miyako 04:54 JST 08 Apr 00:00 JST 08 Apr
Ofunato 05:01 JST 08 Apr 23:50 JST 07 Apr
Kamaishi 05:03 JST 08 Apr 00:00 JST 08 Apr
Kuji-ko 04:54 JST 08 Apr 00:20 JST 08 Apr
FUKUSHIMA PREF. 23:50 JST 07 Apr
Iwaki-shi Onahama 05:28 JST 08 Apr 00:20 JST 08 Apr
Soma 05:19 JST 08 Apr 00:20 JST 08 Apr
IBARAKI PREF. 00:20 JST 08 Apr
Oarai 05:25 JST 08 Apr 00:30 JST 08 Apr
Kamisu-shi Kashima-ko 05:35 JST 08 Apr 00:30 JST 08 Apr

*1 mark: Arrival of tsunami inferred.

Tsunami Warnings and/or Advisories are in currently effect for the following coastal regions of Japan:

MIYAGI PREF.

PACIFIC COAST OF AOMORI PREF.
IWATE PREF.
FUKUSHIMA PREF.
IBARAKI PREF.
Although there may be slight sea-level changes in coastal regions other than the above, no tsunami damage is expected in those coastal regions.

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
Member Since: July 15, 2006 Posts: 178 Comments: 56141
Quoting hurricanejunky:


We did CBS with every 3rd row rebarred and poured with a poured tiebeam. Considering my Grandfather built his old CBS home back in the 1950's with far less rebar and poured concrete and it went thru Donna with 140+ mph winds and only a couple lost shingles, I feel pretty safe. If I had the money though I'd do exactly what you're describing. I'm a big proponent of overkill!!
Oh, I'm all about overkill, too. I live over 70 miles inland, so I don't need protection for full Cat 5 force winds. (not to mention, 8" thick walls would severely limit the natural light able to enter the house - insulation won't be an issue at all, tho).

Basically, I want something that can handle just about whatever the gulf can realistically throw at me. For me to get Cat 5 sustained winds, it would have to be an absurd cat 5 on landfall (talking Camille strength), huge (think Ike-size), and go directly over me. Yes, it could happen, but its doubtful.
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No impact detected at Fukushima nuclear plant following earthquake off north-east coast of Japan
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Quoting AussieStorm:
English Stream.


Tsunami Arrival times.

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six feet of water? we all saw the videos. It's not like one six foot wave. It's like a six-foot tall army of water.
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English Stream.
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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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