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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Well that's better; we closed friday over $113.
-ooops, I'm supposta be ignoring you-
Tuesday: A 50 percent chance of showers and thunderstorms.
Partly sunny, with a high near 75. Breezy, with a west wind between 8
and 16 mph.
and.....
Friday: A 20 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 78.
Friday Night: A 30 percent chance of showers and thunderstorms. Mostly cloudy, with a low around 63.
Saturday: A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 79.
maybe some thunder later but i think most will stay to the south and east of me
hehehehehe
According to an exclusion zone of 30 Kilometer radius, this takes out of the land are of Japan a total of 2827 square kilometers and not only that most of this is very good agricultural land in a country that doesn't have a surplus of it!!
Next and soon, we will see what happens if the clouds of doom and gloom start to gather as the ''company'' now have a very good excuse to say they cant work on the 'problem,' due to new damage and therefore they cant be blamed any longer for what might transpire.
If I was in the board room I my might be saying how do we make a silk purse out of a sows ear with this new development and come up smelling of roses to say we were cheated within sight of a certain victory.
Doomcasters!!
Half the blog may have me on ignore by the end of the season.
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Extended forecast for the panhandle of Florida.....
LONG TERM...
(WEDNESDAY NIGHT THROUGH NEXT MONDAY) NEAR AVERAGE TEMPERATURES AND
FAIR WEATHER ARE EXPECTED THURSDAY AND FRIDAY WITH MAINLY ZONAL FLOW
ALOFT EXPECTED OVER THE SOUTHEAST STATES. THE GFS AND ECMWF FORECAST
A LARGE CLOSED LOW TO DEVELOP OVER THE UPPER MIDWEST BY FRIDAY. THIS
OCCLUDING SYSTEM WILL DRAG A COLD FRONT THROUGH OUR REGION FRIDAY
NIGHT OR SATURDAY AS IT MOVES SLOWLY EASTWARD...WITH THE GFS
OFFERING A SLIGHTLY FASTER SOLUTION THAN THE ECMWF. THIS MEANS A
CHANCE OF RAIN FRIDAY NIGHT THROUGH SATURDAY UNTIL A COOLER AND
DRIER AIRMASS MOVES INTO OUR REGION LATER SATURDAY OR SUNDAY. MUCH
OF THE SOUTHEAST U.S. WILL BE DOMINATED BY A SURFACE RIDGE AND BROAD
UPPER LEVEL TROUGH BY SUNDAY...LIKELY MEANING THAT THE TEMPERATURES
ON SUNDAY AND MONDAY WILL BE QUITE A BIT COOLER (AT LEAST 10 DEGREES
BELOW AVERAGE). DESPITE BEING A THE TAIL END OF THE FORECAST
PERIOD...BOTH GLOBAL MODELS INDICATE INCREASING RAIN CHANCES BY
EARLY NEXT WEEK AS AN APPROACHING UPPER LEVEL SHORT WAVE INTERACTS
WITH A FRONTAL SYSTEM OVER THE NORTHERN GULF OF MEXICO AND
INCREASING DEEP LAYER MOISTURE.
Just curious, did admin pull out the ban stick this weekend and start beating people with it? I got a WU-mail from someone whom was banned, and it piqued my curiosity.
42miles(~67.6kilometres) at 227.1degrees(SW) from FukushimaDaiichi
100miles(~161kilometres) at 23degrees(NNE) from centralTokyo
followed within 42minutes by a magnitude5.2 then a magnitude5.0
(as represented by the two unconnected dots)
And now yet another, a magnitude5.6 (near where the 6.6 struck)
45miles(~72.4kilometres) from FukushimaDaiichi
97miles(~156kilometres) from central Tokyo
It was in the 90's here on Saturday.
Yeah the 6-10 day forecast is for below normal temps here and then it warms back to above normal by the last week of April. Summer weather for good is getting close.
Lordy.....and me the other......LOL
Not many more days of cool weather for us IKE
Plenty of cool air in conjunction with the mid level trough coupled with the entrance region of a 60-70 knot jet and strong surface heating to make quick work of the cap.
A snippet of the latest outlook
(full outlook via link below)
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0728 AM CDT MON APR 11 2011
...PORTIONS OF TN/OH AND LOWER MS VALLEY...
ALL MODELS ARE IN GENERAL AGREEMENT THAT ONGOING CONVECTIVE LINE
WILL ONLY SLOWLY INTENSIFY THIS MORNING DUE TO WARM MID LEVEL
TEMPERATURES SHOWN ON 12Z BMX/JAN/BNA RAOBS. HOWEVER...APPROACH OF
UPPER TROUGH AND DAYTIME HEATING WILL ERODE CAP AND LEAD TO SEVERE
STORMS BY EARLY AFTERNOON.
LOW LEVEL CYCLOGENESIS IS EXPECTED OVER
KY/TN BY MID AFTERNOON...WITH INCREASING LOW LEVEL VERTICAL SHEAR
OVER THE WARM SECTOR. FORECAST SOUNDINGS SUGGEST 0-3KM SRH VALUES
EXCEEDING 300 M2/S2...BUT ALSO SHOW A CONTINUED MID LEVEL INVERSION
WHICH MAY LIMIT UPDRAFT STRENGTH. FOR THIS REASON...HAVE NOT
UPGRADED TO MODERATE RISK AT THIS TIME. HOWEVER...AN UPGRADE MAY
OCCUR LATER TODAY IF CONCERNS REGARDING THERMODYNAMICS ARE LESSENED.
REGARDLESS...POTENTIAL FOR A FEW TORNADOES AND CONSIDERABLE WIND
DAMAGE REMAINS FROM NORTHEAST MS INTO MUCH OF MIDDLE TN/AL AND
SOUTHERN KY. STORMS MAY AFFECT PORTIONS OF NORTH GA TONIGHT BEFORE
DIMINISHING...
13Z SPC DAY 1 Convective Outlook
SENDAI, Japan 2014 A strong new earthquake 7.1 rattled Japan%u2019s northeast Monday as the government urged more people living near a tsunami-crippled nuclear plant to leave, citing concerns about long-term health risks from radiation.
We have a frontal line coming through, but a very dry cap in place at about 850mb. Its not a warm cap (like usual), just a layer where the RH drops from 80% to 40% and under. If you could get rid of that cap, it would be great, we desperately need the rain.
How is everyone this morning?
14 minutes ago
Magnitude: 7.1
DateTime: Monday April 11 2011, 08:16:16 UTC
Region: near the east coast of Honshu, Japan
Depth: 10 km
That is UTC time........that happened several hours ago, 4 hours ago.
USGS has downgraded that quake to a 6.6
"Type: Earthquake
14 minutes ago
Magnitude: 7.1
DateTime: Monday April 11 2011, 08:16:16 UTC
Region: near the east coast of Honshu, Japan
Depth: 10 km"
The latest USGS greater-than-magnitude5 list shows a 5.6 at 11:42:36 UTC
and rates the 8:16:16 earthquake as a magnitude6.6
Viewing: 1701 - 1734
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