Expert forecasts for 2013 N Atlantic season

[ninel conde]

i think they are as baffled as everyone else.

[NDG]

i think they are as baffled as everyone else.

But their reason why their forecast busted makes some sense:

The primary reason why the forecast during the two weeks was a bust was due to the fact that the MJO took a much longer time to amplify into hurricane-conducive conditions than was predicted by the global models in the middle part of August (Figure 3 and 5).
In addition, vertical shear has been much stronger over most of the tropical Atlantic than expected with the seasonal forecast issued in early August

Figure 5: Predicted MJO propagation from August 15 - August 29. The MJO was predicted to propagate into TC-conducive MJO Phase 1 conditions by around August 20. This amplification and propagation took about ten days longer than forecast by the models.

[cycloneye]

CSU released their two week forecast from September 13 thru the 26. Go to the first post of thread to read it.

[hurricanetrack]

Everything has been an over prediction from day one. What an extraordinary season.

[TheStormExpert]

If meteorologist have a hard enough time forecasting the weather days in advance, what makes forecasting a hurricane season months in advance more predictable?

[cycloneye]

CSU released today the two week forecast from September 27 thru October 10. See the forecast at first post.

It calls for below average activity. Here is an excerpt.

Excerpt:

The below-average forecast is due to several factors. No TCs are currently
present in the tropical Atlantic, and only one area east of the Lesser Antilles is given a
low chance of TC formation by the NHC in the next five days. None of the global
models develop any intense TCs during the next week.
The MJO is currently in Phase 6, which is an unfavorable phase for Atlantic TC
formation. Most global models indicate relatively little movement of the MJO out of
Phase 6 during the next two weeks. In general, these harsh sub-seasonal conditions
combined with the anemic activity that has occurred so far this year indicates that the
likelihood of significant activity during the next two weeks is quite low.

VERIFICATION OF SEPTEMBER 13 – SEPTEMBER 26, 2013 FORECAST

The two-week forecast of tropical cyclone activity from September 14- September 27 verified somewhat lower than expectations. While not much additional TC formation was expected during the two-week time span, we expected that Hurricane Humberto would last longer and intensify more than it did. Activity at average levels (70-130% of normal) was predicted (15-28 ACE units), while observed activity was at below-average levels (8 ACE units). ACE generated during the two-week period came from Gabrielle, Humberto, and Ingrid.

['CaneFreak]

Can't go wrong with that forecast the way this season has been panning out.

CSU released today the two week forecast from September 27 thru October 10. See the forecast at first post.

It calls for below average activity. Here is an excerpt.

Excerpt:

The below-average forecast is due to several factors. No TCs are currently
present in the tropical Atlantic, and only one area east of the Lesser Antilles is given a
low chance of TC formation by the NHC in the next five days. None of the global
models develop any intense TCs during the next week.
The MJO is currently in Phase 6, which is an unfavorable phase for Atlantic TC
formation. Most global models indicate relatively little movement of the MJO out of
Phase 6 during the next two weeks. In general, these harsh sub-seasonal conditions
combined with the anemic activity that has occurred so far this year indicates that the
likelihood of significant activity during the next two weeks is quite low.

VERIFICATION OF SEPTEMBER 13 – SEPTEMBER 26, 2013 FORECAST

The two-week forecast of tropical cyclone activity from September 14- September 27 verified somewhat lower than expectations. While not much additional TC formation was expected during the two-week time span, we expected that Hurricane Humberto would last longer and intensify more than it did. Activity at average levels (70-130% of normal) was predicted (15-28 ACE units), while observed activity was at below-average levels (8 ACE units). ACE generated during the two-week period came from Gabrielle, Humberto, and Ingrid.

[cycloneye]

The CSU October/November Caribbean forecast is up at first post. They call for above average period with 11 ACE units generated.

[CrazyC83]

What phase is MJO in right now? Based on global activity, this seems like a Phase 4 or 5 setup with the Indian Ocean and extreme western Pacific (i.e. not near the dateline) being where the activity is.

[cycloneye]

What phase is MJO in right now? Based on global activity, this seems like a Phase 4 or 5 setup with the Indian Ocean and extreme western Pacific (i.e. not near the dateline) being where the activity is.

The North Atlantic basin has a last opportunity to develop something between late October and early November. A caveat is that the last one didn't cause the activity expected.

[hurricanes1234]

The following is only my personal opinion, but I don't see anything significant forming for the rest of this season. Maybe only weak tropical storms, but I just can't imagine even a 100 mph Category 2 hurricane for the rest of this year. Imagine in August, we had 0 hurricanes, and only 2 or 3 weak named storms, and in September, two hurricanes, one of which was strongly sheared. None of them made it above 85 mph. Yes, storms early in the season formed in the deep tropics, but they were extremely weak and dried out. The season hasn't changed since June 1st, and I don't see anything considerable changing until next year. As cycloneye pointed out, the MJO earlier this year did little to nothing in terms of storms and their ACE-levels in both the Atlantic and East Pacific, but especially the Atlantic. So even if Phase 1 does return, I would reiterate that I see nothing changing in terms of ACE. And we are rapidly approaching November, likely not enough time in my opinion for the Atlantic to wake up out of its 2013 slumber. I can also fully imagine an early end to the 2013 hurricane season, seeing that there wasn't much to begin with.

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[Ntxw]

This has been a horrifying prediction year for CSU from start to finish. The latest prediction of above normal activity Oct/Nov will fail again. Average is 6.3, prediction is 11 ACE units we ended up with a little over 5. Every time they have forecasted above average this season it has never come to fruition. The weeks they predicted below average have been spot on.

Not to only pick on them, just that they are the most respected group we go by. I've failed at predicting values as well, just about everybody.

[cycloneye]

It will be very interesting to read the CSU verification report that will be up by the end of this month.

[cycloneye]

Breaking News=CSU verification of 2013 season is up,Will suspend future forecasts

The big news is that they will not issue forecasts unless they get funded. Read the 61 pages at first post of thread.

NOTICE OF FORECAST SUSPENSION
The Tropical Meteorology Project has been issuing forecasts for the past thirty years. These predictions have served as a valuable information tool for insurance interests, emergency managers and coastal residents alike. While these forecasts were largely developed utilizing funding from various government agencies, recent attempts at obtaining continued grant funding have been unsuccessful. Funding from several insurance companies enabled the continuation of these forecasts in recent years. However, the forecast team has recently lost some of its financial support from industry. Consequently, new sources of revenue are required to keep the forecast going. Interested parties are invited to contact Phil Klotzbach directly via email at philk@atmos.colostate.edu for additional discussion of potential sponsorship opportunities.
The Tropical Meteorology Project will suspend issuing seasonal forecasts beginning in April 2014, unless additional funding for the forecasts is forthcoming. The CSU forecast team is currently seeking partnerships with the private sector in order to continue these predictions. Please see the sponsorship brochure if you are interested in supporting the forecast team.

[Ntxw]

Absolutely great read. As bad as they performed, I am always amazed at their skills and reasoning definitely some of the best.

As far as the paper, this just about sums up the season and the forecasts.

The majority of most inactive hurricane seasons are associated with El Nino years. That was not the case this year. There was no El Nino in 2013. There were a number of inhibiting tropical Atlantic parameters which unexpectedly occurred this season such as have been discussed earlier. These negative parameters were responsible for the low hurricane activity which resulted. But the more basic question is why did so many of these negative hurricane genesis parameters occur when most of our large-scale pre-season precursor climate signals appeared similar to those which occur before most of theprevious active seasons?

We believe that much of the explanation for the lack of activity this year was due to a significant weakening of our proxy of the Atlantic THC from April through June. Our THC proxy signals of April-June 2013 indicate that the Atlantic THC (from both W.ATL and E. ATL proxy signals) had the strongest drop and was the weakest overall of any year since 1950. We hypothesize that this very large springtime collapse of the THC set up broad-scale conditions that likely related to the unusually dry mid-level air, stronger-than-normal mid-level subsidence and stronger than expected vertical wind shear in the Atlantic MDR, Caribbean and Gulf of Mexico

A couple of things I've learned this season. The cliche of the waters are so warm it has to form something or whatever forms will explode is simply not true. During the season by early summer the waters are always warm enough for fueling the strongest storms but it is not that which dictates if one will form, more times than not it is the Atmosphere. Second we now have two extremes for neutral years and we can stop with the it has to be active because it is neutral (yes you 2005 as the culprit).

[hurricanes1234]

Nothing this year went as expected. Not one thing. From the entire season in general, down to model storms not materialising, then to storms not strengthening as anticipated - everything this year has been unexpected. And I blame or point fingers at no one, because even the most skilled forecasters didn't expect a dud season like this to pan out. I guess, as with anything, there are these occasions when everything goes wrong or in a different direction, and unfortunately, 2013 is that year. I don't think any season in the near future will be as mysterious as this one has been. Look at now, for example. Everyone of us could have sworn that the season was over last month, yet, we have a late-season bloomer - Melissa that came out unexpectedly and made the season last very long, from June 5 to very late November, which most seasons cannot fulfill. It's just an odd season period, hands down.

[somethingfunny]

The best part of the Verification paper is on page 60.

[cycloneye]

Interesting articule about why the experts blew their 2013 forecasts.

Why did all the experts get the hurricane season outlook so wrong?

Twelve forecast teams predicted an average of 16 named storms, including eight hurricanes, four major. Yet this season, which ends Saturday, saw only 13 named storms, including two mediocre Category 1 hurricanes.

"Pretty much everyone who tried to forecast the number of hurricanes bombed," said Jeff Masters, chief meteorologist of Weather Underground, an online weather site.

Forecasters say they didn't foresee that a large-scale atmospheric wind pattern would blanket the tropical Atlantic with dry, sinking air. And they didn't anticipate that Saharan dust would further dry out the atmosphere.

Finally, they failed to anticipate that cooler waters would infiltrate the Atlantic in the spring. That helped stymie storm formation and keep those that did emerge relatively weak and short-lived.

"I think the magnitude of the cooling that occurred in the Atlantic was somewhat overlooked by ourselves and others," said Phil Klotzbach, who along with William Gray initially forecast 18 named storms, including nine hurricanes. "It was one of the largest busts for our research team in the 30 years we've been issuing this report."

The National Oceanic and Atmospheric Administration said it, too, was fooled by the arrival of so much dry air. It made this year the sixth-least-active Atlantic hurricane season since 1950, in terms of the collective strength and duration of named storms. The agency in May predicted up to 20 named storms, including up to 11 hurricanes.

"A combination of conditions acted to offset several climate patterns that historically have produced active hurricane seasons," said Gerry Bell, NOAA's lead hurricane forecaster. "As a result, we did not see the large numbers of hurricanes that typically accompany these climate patterns."

Before the season started in June, forecast teams thought a highly active season was brewing because wind shear was expected to be relatively low, tropical waters were projected to be abnormally warm and west African rainfall, which acts to energize tropical waves, was predicted to be heavy. Additionally, El Niño, the atmospheric force that suppresses storm formation, wasn't expected to develop.

Even in early August, NOAA predicted up to nine hurricanes, five major. Klotzbach and Gray forecast eight hurricanes, three major.

The forecast agency that came closest was Tropical Storm Risk, a British weather firm, which in early August called for 14.8 named storms, including 6.9 hurricanes, three major.

Tropical storm Andrea, the first of the season, was the only named storm to hit the U.S. coastline this year. It initially hit Northwest Florida in June and then generated tornadoes, heavy rain and flooding to portions of Florida, Georgia and South Carolina, causing one fatality.

Otherwise, most of this year's systems remained at sea and didn't last long. Of the 13 named storms, nine existed for three days or less, with the last one being Tropical Storm Melissa, which died in the Central Atlantic last week.

Because so many forecast teams misread the atmospheric signals, Klotzbach said, "people will probably not put as much stock in seasonal forecasts next year. You're only as good as your latest forecast."

http://articles.sun-sentinel.com/2013-1 ... hurricanes

[cycloneye]

Here is NOAA statement about the 2013 forecast that busted.


With just a few days left in the 2013 hurricane season, NOAA issued its end-of-season press release this morning. Thirteen named storms formed in the Atlantic basin this year. Two of these (Ingrid and Humberto) became hurricanes, but neither became a major hurricane (category 3 or higher), and in fact, neither Ingrid nor Humberto even reached category 2.

NOAA’s seasonal hurricane outlook, issued by the Climate Prediction Center back on May 23rd, called for a 70% chance of an above-normal season, a 25% chance of a near-normal season, and a 5% chance of a below-normal season. Even in August, NOAA’s confidence in an above-normal season was still high; the August update called for 13-19 named storms, 6-9 hurricanes, and 3-5 major hurricanes. Although the number of named storms did fall within the forecast range, the numbers of hurricanes and major hurricanes were well below the forecast range, and also well below the long-term averages of 6 and 3, respectively.

The season was so quiet that NOAA and the U.S. Air Force Reserve Hurricane Hunters flew only 45 aircraft reconnaissance missions over the Atlantic basin, and the total number of hours flown, 435, was the fewest since at least 1966 (and probably longer, but older records on flight hours are hard to come by). This year had the fewest number of hurricanes since 1982; it was also the first year since 1994 without a major hurricane. In terms of ACE, the collective strength and duration of the season’s subtropical storms, tropical storms, and hurricanes, 2013 will likely end up as the sixth-quietest Atlantic hurricane season since 1950.

So what happened? The obviously unexpected (but fortunate) lack of strong storms was related primarily to sinking motion and very dry air across portions of the tropical Atlantic Ocean. In addition, wind shear was higher than normal over portions of the basin, especially in the Gulf of Mexico and the Caribbean Sea. These conditions offset otherwise more “active” climate patterns, such as above-average sea surface temperatures in the tropical Atlantic and a lack of an El Nino.

So you might ask - why all the persistent sinking and dry air this year? That’s a good question, but there don’t appear to be any definitive or satisfying answers at the moment. Clearly there are some aspects of seasonal hurricane prediction - especially the factors that affect the ability of the atmosphere to support deep thunderstorm activity - that are not yet very predictable, even just a few weeks in advance. When these patterns take an unexpected turn, the seasonal forecast will fail.

It’s worth noting that even though the season overall was quiet, Mexico was repeatedly affected by tropical cyclones this year, including three in the Atlantic and five more from the eastern North Pacific. And it’s also worth noting that even quiet seasons can bring massive devastation (remember Andrew in 1992?). So regardless of whether the season is quiet or active, regardless of whether the outlook says above- or below-normal, residents of hurricane-vulnerable areas always need to prepare each and every season as though this is one that’s going to affect them – and then feel very fortunate if the season ends without any impacts.

Given this, you might ask why does NOAA bother to make a seasonal hurricane outlook at all, since it doesn’t seem to have much direct practical benefit. Well, in most years the outlooks are actually skillful, but the best answer from our perspective is that the outlooks raise awareness of the hurricane threat. It’s fascinating that at NHC the question we get more often than any other is “How busy is the season gonna be?”. People clearly have a deep curiosity about this, even if the forecast is not about them specifically. So we know that we’ll get folks' attention for a few minutes if we make and publicize these forecasts. And our hope is that while we have their attention, people will start thinking about their own vulnerabilities - and make sure they’re prepared if a storm should threaten.

https://www.facebook.com/US.NOAA.Nation ... ?ref=br_tf

http://www.noaanews.noaa.gov/stories201 ... eason.html

[WeatherGuesser]

To me, one of the most noteworthy points is that despite everyone's proclamations on how unusually quiet it was, there seem to have been no records set to cement that position.