Another 'above-normal' hurricane season forecast for the Atlantic

[TomLewis]

They would probably be vilified if they predict below average and just cautious for predicting above average. So there technique is junk.

[Tkeeth]

It is like roulette...they keep doubling down on black hoping to win

[leboyd]

Originally Posted by Sailmonkey

Are you kidding!!!

That would be a great job! Wrong most of the time and your product is still sought out!!

Maybe that's right, but since every dislikes you and makes you the brunt of their jokes, I'll stick to my original statement.

I prefer a job where people expect me to be right and where I'm generally liked okay.

[leboyd]

I think the reason why "This year is expected to be great than average" seems to be repeated after years of below average is because part of the algorithm for the prediction software probably takes into account how many "below average" recent years. "Regression to the Mean" provides a large input in many prediction algorithms because, "Well, if this is average and we haven't been above average in a while, we got to have above average outcomes soon."

While it's in general true, trying to figure out how much value to put on this is difficult. Likewise, with only maybe fifty to 100 years of some data (not all) on TS and hurricanes, how would we really know what "average" is? What we think is "average" could really be above average.

[Pete7]

Originally Posted by catjlin

For the upcoming Atlantic hurricane season, forecasters predict a 45 percent chance of an above-normal season,

So there is a 55% chance of a normal season, sounds good more time for sailing.

Pete

[leboyd]

Originally Posted by Pete7

So there is a 55% chance of a normal season, sounds good more time for sailing.

Pete

Sort of... It's 55% of a "normal" or a "below average" season. If you had an equal balance of the 3 (which might be a "normal" year), it would be 33% each (yeah, yeah 33.333334).

[StuM]

Originally Posted by leboyd

I think the reason why "This year is expected to be great than average" seems to be repeated after years of below average is because part of the algorithm for the prediction software probably takes into account how many "below average" recent years. "Regression to the Mean" provides a large input in many prediction algorithms because, "Well, if this is average and we haven't been above average in a while, we got to have above average outcomes soon."

While it's in general true,...

Nope, it's not "generally true".

It's commonly known as the "Gamblers Fallacy" and many people have gone broke working on that assumption. It doesn't matter what the last x number of years have been, that has no effect on what next year is going to be.

[Pelagic]

Originally Posted by zboss

Still waiting on the TSR report which comes out in a few days. Its my understanding that this report is the most reliable from a historical standpoint.

Tropical Storm Risk (TSR) for long-range forecasts of hurricane, typhoon and cyclone worldwide

Yes...TSR is the best predictor of tropical revolving storms.

For those who are affected, it is really worth monitoring and studying what they are saying.

Keep in mind, they keep updating ACE as the season evolves, so while early predictors often have a low percentage of confidence, each subsequent one gets better and you can plan accordingly to be a better Neighbour.

Our Typhoon season is about to begin so we had and update May 5th.

Extended Range Forecast for Northwest

Pacific Typhoon Activity in 2017
Issued: 5th May 2017
by Dr Adam Lea and Professor Mark Saunders

Dept. of Space and Climate Physics, UCL (University College London), UK

Forecast Summary

TSR predicts the 2017 Northwest Pacific typhoon season will see activity slightly above norm. However, forecast uncertainties remain large.

The TSR (Tropical Storm Risk) extended range forecast for Northwest Pacific typhoon activity in 2017anticipates a season with upper tercile activity to moderately high (63%) probability.

The forecast spans the period from 1st January to 31st December 2017 (95% of typhoons occur historically after 1st May) and employs data through to the end of April 2017.

The forecast includes deterministic and probabilistic
projections for overall basin activity, and deterministic projections for the ACE index and numbers of intense typhoons, typhoons and tropical storms.

TSR’s main predictor for overall activity is the forecast anomaly in August-September Niño 3.75 (region 5˚S-5˚N, 140˚W-180˚W) sea surface temperature (SST)
which we anticipate being 0.59±0.5°C warmer than normal (1965-2016 climatology).

A warm Niño 3.75 SST would have an enhancing effect on typhoon activity. However, sizeable uncertainties remain in the ENSO forecast for August-September 2017.

Updated forecasts for Northwest Pacific seasonal typhoon activity will be issued in early July and early August.

NW Pacific ACE Index and System Numbers in 2017

ACE Intense Tropical Index Typhoons Typhoons Storms

TSR Forecast (±FE) 2017 357 (±84) 10 (±3) 17 (±3) 27 (±4)

52yr Climate Norm (±SD) 1965-2016 297 (±101) 9 (±3) 16 (±4) 26 (±4)

Forecast Skill at this Lead 1965-2016 30% 28% 16% 6%


Key:
ACE Index = Accumulated Cyclone Energy Index = Sum of the Squares of 6-hourly Maximum Sustained

Wind Speeds (in units of knots) for all Systems while they are at least Tropical Storm Strength.

ACE Unit = x104 knots2

Intense Typhoon = 1 Minute Sustained Wind > 95Kts = Hurricane Category 3 to 5.

Typhoon = 1 Minute Sustained Wind > 63Kts = Hurricane Category 1 to 5.

Tropical Storm = 1 Minute Sustained Winds > 33Kts.

SD = Standard Deviation.

FE (Forecast Error) = Standard Deviation of Errors in Cross-Validated Hindcasts 1965-2016.

Forecast Skill = Percentage Improvement in Mean Square Error Afforded by Cross-Validated Hindcasts 1965-

2016 over Hindcasts Made with the 1965-2016 Climate Norm.

Northwest Pacific = Northern Hemisphere Region West of 180o

W Including the South China Sea. Any Tropical Cyclone (Irrespective of Where it Forms)

[StuM]

Originally Posted by leboyd

Sort of... It's 55% of a "normal" or a "below average" season. If you had an equal balance of the 3 (which might be a "normal" year), it would be 33% each (yeah, yeah 33.333334).

But what if the system is reasonable stable and a "normal year" has a 50% chance of "average" and 25% probability of above or below average?

Or more statistically robust, what if:

Annual hurricane frequency approximates a "normal" distribution (bell curve) and "average" means within one standard deviation.

In that case a "normal" year has (roughly) a 68% chance of "average" and 17% chances of above and below "average".


IOW, without defining "average" and "normal", the prediction is, like so many such forecasts, meaningless.

[boatman61]

I think most forecasters are afraid of doing a 'Michael Fish'..
Video: The Great Storm: Michael Fish's 1987 hurricane forecast blooper - Telegraph

[zedpassway]

Originally Posted by TomLewis

Funny, I haven't heard a below average prediction in years, wonder why?

You know why!!! Just say it.

[leboyd]

@StuM: Did I cut you off is traffic this morning?

"Generally True" is exactly as I described it. Sure, "chasing bets" will make you go broke, but the law of large numbers easily says you will have regression to the mean. What I said was we can't even be comfortable with what the HC says is "normal" be cause we don't have enough data.

In my 33/33/33, I thought is was obvious that I was only giving an example of what they might call "normal". Of course, a 25/50/25 might also be true. And as you say, there might be even something different. Since the HC doesn't tell us, we don't really know what they call "normal" or "average," let alone how the calculate it.

[a64pilot]

Originally Posted by StuM

Nope, it's not "generally true".

It's commonly known as the "Gamblers Fallacy" and many people have gone broke working on that assumption. It doesn't matter what the last x number of years have been, that has no effect on what next year is going to be.

You flip a quarter and three times in a row it comes up heads, the fourth flips odds are still 50/50 though.

[a64pilot]

Originally Posted by boatman61

I think most forecasters are afraid of doing a 'Michael Fish'..

Video: The Great Storm: Michael Fish's 1987 hurricane forecast blooper - Telegraph

Yes, nobody complains too much if you cry wolf, but buddy tell them it's going to be OK and its not and you will be remembered.
In the US it was the 1900 Galveston Hurricane, I think it is still the most deadly single event in US history, local weather expert had said Galveston was immune to Hurricanes due to the shallow water, I don't remember his name, and I think he lost his wife to the storm, but he is infamous to this day.

Found him, this guy
https://en.m.wikipedia.org/wiki/Isaac_Cline

[ohdrinkboy]

I blame it all on global warming