Early 2011 Atlantic Hurricane Season Forecasts

By: Dr. Jeff Masters , 06:22 AM GMT del 07 Aprile 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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Quoting Neapolitan:

My guess is that global warming arguments will go away at roughly the same time that global warming itself goes away. Until then, well, what is, is.

Australia produces 1.2% of the worlds pollution. As of July 1 2012 we will be taxed $35/tonne of CO2 a household produces. This includes businesses including steel producers like Bluescope Steel formally BHP steel. This will force these manufacturing companies out of Australia to more than likely China. This will cause the employment rate to go from it's current 5.5% to 10-15%. The introduction will also force the price of everything needed to live to go up. This new tax will cost the average household $1580 a year, if including the cost of the tax on everything else..... who knows.... $5000 extra a year.... ???

This all from a report from Prof. Ross Garnaut who is a Distinguished Professor of Economics at the Australian National University and both a Vice-Chancellor's Fellow and Professorial Fellow of Economics at The University of Melbourne. Not a climate scientist. feel free to google his name to find out which company boards he's on. I think his mind isn't on climate but on whats going to be streaming into his bank account, if you get what i mean.
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Hi Keeper,
We're 84-point-something now and will be in the 80s all week.
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This may be old news to some of you:

Earthquake Information (Earthquake Information)
Issued at 22:01 JST 09 Apr 2011

Occurred at (JST) Latitude
(degree) Longitude
(degree) Depth Magnitude Region Name
21:58 JST 09 Apr 2011 30.0N 131.9E 10 km 5.7 Tanegashima Nanto-oki

This earthquake poses no tsunami risk.

From Japan Meteorology Agency Link
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Quoting KEEPEROFTHEGATE:
gonna get warm fish temps just above 20c tomorrow with a poss severe outbreak in afternoon then in high 60's mon with more severe poss. then mild the rest of the week with daytime temps at or above 60 with night temps high 40's or low 50's as for snow its done a slight chance of a cool down around the 20th of april for a couple of days so maybe we get a few flurries but i beleive any significant snows for the lakes are pretty well done till next winter


Oh well.. I can hope :)
You ready to jump on the Canucks bandwagon yet?
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1029. KEEPEROFTHEGATE (Mod)
Quoting Orcasystems:


You must be due for at least one last snowfall... I hope :)
gonna get warm fish temps just above 20c tomorrow with a poss severe outbreak in afternoon then in high 60's mon with more severe poss. then mild the rest of the week with daytime temps at or above 60 with night temps high 40's or low 50's as for snow its done a slight chance of a cool down around the 20th of april for a couple of days so maybe we get a few flurries but i beleive any significant snows for the lakes are pretty well done till next winter
Member Since: Luglio 15, 2006 Posts: 165 Comments: 52261
Quoting Orcasystems:


or you do.

Nah, my going away wouldn't end the disagreements between Big Energy and their political lackies on the one side, and climate scientists on the other. But I do appreciate your ad hominem, no matter how lame or predictable. ;-)
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Quoting KEEPEROFTHEGATE:
next outlook for day 2 comes out in about 60 mins or so iam expecting an upgrade to high risk at that time


ok
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Quoting washingtonian115:
Oh god.A global warming debate.I thought we got rid of them.

Dr. Masters is a pivotal and highly credible point man for the scientific view so you will see much more discussion here.
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Quoting KEEPEROFTHEGATE:


You must be due for at least one last snowfall... I hope :)
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Quoting Neapolitan:

My guess is that global warming arguments will go away at roughly the same time that global warming itself goes away. Until then, well, what is, is.


or you do.
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1023. KEEPEROFTHEGATE (Mod)
Quoting Tazmanian:



ouch
next outlook for day 2 comes out in about 60 mins or so iam expecting an upgrade to high risk at that time
Member Since: Luglio 15, 2006 Posts: 165 Comments: 52261
Quoting Neapolitan:

No, it's been determined: increasing concentrations of CO2 are responsible for the warming, and mankind's contribution to that increase is somewhere between "most of it" and "all of it". Scientists are concerned about the ramifications of that, so it really is something to focus on--and, as much as I like both playing and watching golf, it's far more important than that game. Even an exciting Masters. Ya' know? ;-)


I have asked you multiple times... for a number..any number.. even one per reviewed and verified by one of your esteemed sources... there isn't one?

You cannot keep coming on here and beating yours/ours/theirs head against the wall... when you cannot even prove a percentage?

Give me a proven verified number??

Do we contribute.. yes... are we 100% responsible... 50%... 25%.... tell me.

"most of it" and "all of it". is not a scientific anything.
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1021. KEEPEROFTHEGATE (Mod)
Member Since: Luglio 15, 2006 Posts: 165 Comments: 52261
Quoting KEEPEROFTHEGATE:
THE EXIT
REGION OF THE JET WILL OVERSPREAD THE UPPER MS VALLEY SUNDAY
AFTERNOON CREATING STRONG DEEP LAYER SHEAR PROFILES VERY FAVORABLE
FOR SEVERE STORMS. THIS COMBINED WITH STRONG INSTABILITY WILL RESULT
IN A SIGNIFICANT POSSIBILITY FOR SUPERCELLS AND TORNADOES ACROSS THE
MODERATE RISK AREA. AN UPGRADE TO HIGH RISK APPEARS LIKELY ACROSS A
PORTION OF THE UPPER MS VALLEY IN LATER OUTLOOKS



ouch
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Quoting Orcasystems:


OMG.. not again :(

Planet warming up... yes
Responsibility... yet to be determined.

Now go FOCUS on something else.

No, it's been determined: increasing concentrations of CO2 are responsible for the warming, and mankind's contribution to that increase is somewhere between "most of it" and "all of it". Scientists are concerned about the ramifications of that, so it really is something to focus on--and, as much as I like both playing and watching golf, it's far more important than that game. Even an exciting Masters. Ya' know? ;-)
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Quoting washingtonian115:
Oh god.A global warming debate.I thought we got rid of them.

My guess is that global warming arguments will go away at roughly the same time that global warming itself goes away. Until then, well, what is, is.
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Quoting cat5hurricane:

I really think you're right, bud. Take a look at this:

SPC Day 3 Moderate Risk for Severe Thunderstorms: Just How Rare is it?


My experience with seeing moderate risks the days before are that it's a fair chance part of that enclosed area could be upgraded to a 'high' risk area the next day.

I usually am not one to hype, but this one bares watching.


yup i find it vary rare too find it mod risk on day 3
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1014. KEEPEROFTHEGATE (Mod)
Quoting Tazmanian:
sunday is looking like are 1st high risk day
THE EXIT
REGION OF THE JET WILL OVERSPREAD THE UPPER MS VALLEY SUNDAY
AFTERNOON CREATING STRONG DEEP LAYER SHEAR PROFILES VERY FAVORABLE
FOR SEVERE STORMS. THIS COMBINED WITH STRONG INSTABILITY WILL RESULT
IN A SIGNIFICANT POSSIBILITY FOR SUPERCELLS AND TORNADOES ACROSS THE
MODERATE RISK AREA. AN UPGRADE TO HIGH RISK APPEARS LIKELY ACROSS A
PORTION OF THE UPPER MS VALLEY IN LATER OUTLOOKS
Member Since: Luglio 15, 2006 Posts: 165 Comments: 52261
Oh god.A global warming debate.I thought we got rid of them.
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sunday is looking like are 1st high risk day
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Quoting cat5hurricane:

You got it, Orca. Down here at Augusta National and thought I'd bounce in on my iPhone to check the blog. It was going along well until I see these never-ending, blanket acedotal non-science arguments being thrown around about AWG. That, I take offense to.

But, I'm done here. Back to a beautiful sunny morning in SE Georgia among the Georgia pines about ready to settle in and hopefully watch Phil Michelson get a fourth green jacket.

Out till Monday >>

He's gotta beat Aussie Jason Day.
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Complete Update





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Quoting cat5hurricane:

You got it, Orca. Down here at Augusta National and thought I'd bounce in on my iPhone to check the blog. It was going along well until I see these never-ending, blanket acedotal non-science arguments being thrown around about AWG. That, I take offense to.

But, I'm done here. Back to a beautiful sunny morning in SE Georgia among the Georgia pines about ready to settle in and hopefully watch Phil Michelson get a fourth green jacket.

Out till Monday >>


OK, now I am jealous.. I have been watching it on TV... my favourite show of the year. (even if Mike Weir played like an idiot)
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Quoting cat5hurricane:

Not so fast there. You really believe there is no argument whatsoever that the planet is warming up? That is definitely NOT TRUE. Take a look at the past 6 months of the blog entries here and try coming back and telling me that there is ABSOLUTELY NO argument that the planet is warming up. Not too mention, I'm only talking about this blog, as I'm willing to suspect there are many more scientific based fronts (blogs, magazines, scientific journals {peer reviewed or not}) on which such disagreements are very prevalent.

Or, if you are referring to only certain peer groups you are willing to recognize based solely on preconceived biases on AWG to conjure such a blanket statement, then perhaps then you are correct, and thus I'll rest my case.

But until then, nice try there, bud.

Sorry, Cat5; when I said "there is no argument", I meant there is no credible scientific argument. None whatsoever. Of course there are ideological and profit-based arguments that say otherwise, but that's not what I had in mind.

My apologies for not making that more clear.
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Quoting cat5hurricane:

Not so fast there. You really believe there is no argument whatsoever that the planet is warming up? That is definitely NOT TRUE. Take a look at the past 6 months of the blog entries here and try coming back and telling me that there is ABSOLUTELY NO argument that the planet is warming up. Not too mention, I'm only talking about this blog, as I'm willing to suspect there are many more scientific based fronts (blogs, magazines, scientific journals {peer reviewed or not}) on which such disagreements are very prevalent.

Or, if you are referring to only certain peer groups you are willing to recognize based solely on preconceived biases on AWG to conjure such a blanket statement, then perhaps then you are correct, and thus I'll rest my case.

But until then, nice try there, bud.


OMG.. not again :(

Planet warming up... yes
Responsibility... yet to be determined.

Now go FOCUS on something else.
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Link

hey take a look in the eastern pacific dosent it look as if the first storm wants to form soon???
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Member Since: Luglio 15, 2006 Posts: 165 Comments: 52261
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Quoting twincomanche:
Coolest March since 1994.

http://www.accuweather.com/blogs/climatechange/st ory/48140/coolest-march-since-1994.asp

True. But as the article to which you linked points out: "Despite the recent cooling, the decadal temperature trend for the lower troposphere remains upward at + .145 C."

The planet is definitely warming up; there's no argument there, anyway...
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Member Since: Luglio 15, 2006 Posts: 165 Comments: 52261
Quoting Neapolitan:

The big companies always leave a bad taste in my mouth, whether through personal experience or the experiences of those I know. Two very small anecdotes to help illustrate my point:

1) My ex in-laws own a handful of properties in South Florida. One old rental in Hollywood had been covered by Allstate for 33 years with nary a claim until Andrew hit. That storm dropped a ficus branch on the front porch, doing less than $2,000 damage. They filed a claim--again, their first ever on that property--and Allstate sent them a check in the mail...followed two weeks later by a letter of policy cancellation telling them they were considered "too large a risk". For months after Andrew, the same story was heard from all over: good folks who'd paid premiums for decades were suddenly told to go away for having the temerity to actually use the service for which they'd been paying.

2) I was a loyal GEICO car insurance customer for many years in South Florida, and never filed a claim, got no tickets, was never involved in an accident, and all that. I sold the rights to a software product in 1999 to a company in Santa Barbara, California, so moved out there as part of the deal. GEICO raised my rates a little over 30%, explaining that I was moving to a much more risky area, so they needed to compensate. I didn't like it, but I understood. A year later, however, I had to move back to Miami for a year to fulfill a contractual obligation. I notified GEICO--who proceeded to raise my rates a little over 30%, explaining that I was moving to a much more risky area, so they needed to compensate. Say what? I explained--patiently at first, then more angrily--that I though they were full of bovine egesta, but they refused to capitulate. So I dumped them.

My point being, big insurers spend millions on catchy jingles and touchy-feely commercials and CGI geckos with British accents. But when the rubber meets the road--or when the ficus meets the front porch--you, the customer, suddenly go from being a long-term asset to a short-term liability...and all that feel-good stuff they so loudly trumpet means absolutely nothing.


That's so true man. Big companies don't give a crap about customers, or anyone else. All they care about is making a bigger profit. Because being a multi-millionaire is just never enough. They MUST make more, always more. An insatiable apatite for greed and wealth. Money will make people do the most wicked things, just for money, when money becomes their god.

People hate taxes, and government regulation, but without government regulation, people would be at the full mercy of the companies, something I would never want to experience. Just take a look into the forgotten history of the industrial era in America. Its almost as shameful if not just as much as the civil war that preceded it.

For the tea party guys who think Libertarianism will work, well, they don't know their history. Just as too much government control of the system, that is socialism or communism on the other extreme which leads to failure, a tiny government that has no say in the capitalist world leads to a cold, cruel, and ugly society, also leading to failure.

Obama isn't even close to being a communist, although he favors a little too much government intervention then I'd like, better that then no regulation at all.

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GRAND FILAMENT: A magnificent filament of magnetism is curling around the sun's southeastern quadrant today. Measuring more than 700,000 km from end to end, the vast structure is about twice as long as the separation between Earth and the Moon. Arrows trace the filament's meandering path in this extreme UV image from NASA's Solar Dynamics Observatory:



It's not easy for such a filament to remain suspended indefinitely above the stellar surface, and indeed a collapse is possible. Filaments falling onto the sun can trigger explosions called "Hyder flares." Is one in the offing? Readers with solar telescopes are encouraged to monitor developments.



Picture didn't post. link.Link
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Quoting DARPAsockpuppet:
94 mph wind gust reported in Ponca City 1 hr. 20 minutes ago when that cell rolled through there:


Ponca City, Oklahoma (Airport)
Updated: 1 hr 20 min 44 sec ago
70 %uFFFDF
Heavy Thunderstorm Rain Fog Squall
Humidity:
88%
Dew Point:
66 %uFFFDF
Wind:
48 mph
from the
NW



Wind Gust:
94 mph
Pressure:
29.62 in
(Rising)



Action:
Quote
| Ignore User


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My gosh that's powerful wind gusts topped 91 mph here in the super cell that came across my area last Thursday in the severe weather outbreak. Peak winds in the storm were actually rated to an incredible 105 mph wind gusts.
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Quoting Grothar:


No, please leave a message at the sound of the beep.

(Beep)

LOL
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Quoting Skyepony:


The tropical invests/storms & around Darwin have played a roll in the positive SOI. I've also noticed, atleast with the 90day SOI (which smooths some of that) that it's 50/50 on which moves first out of ENSO or SOI when we're coming out of a mod La Niña. ESPI on the other hand always goes Neg before ENSO moves positive. Which makes sense as the K-waves that begin to propagate causing the switch is picked up first by the rain anomalies before we see the results in the sea temps anomalies.


The tropical Pacific Ocean warmed only slightly over the last fortnight, with temperatures continuing to approach their normal values for this time of year. The recent warming in the Pacific Ocean is consistent with the life cycle of past La Niña events, which tend to decline during the southern hemisphere’s autumn. All available climate models suggest further weakening of the La Niña over the coming months, with a return to neutral conditions likely by the southern hemisphere winter.

Contrasting with the ocean, atmospheric indicators of the La Niña including trade winds, cloudiness and the Southern Oscillation Index (SOI) have shown little trend and remain consistent with a well developed La Niña event. These atmospheric indicators are expected to return to neutral over the coming months in response to changes in the ocean.
From Australian BOM ENSO Wrap-Up on March 30.
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Quoting emcf30:
TEST is anyone there?


No, please leave a message at the sound of the beep.

(Beep)
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This quake was a lot south of the Mega quake zone, I would say its a separate event and not an aftershock, I just hope it's not a fore-shock to another mega quake.
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About JeffMasters

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