Atlantic Hurricane/Invest Thread 2012/2013

[summer blizzard]

60% for 96L now, should be some Fujiwara interaction which will send it north west but the east coast should be on alert.

[summer blizzard]

96L IS now TD10 and will be declared at the next advisory.

[summer blizzard]

97L looks interesting, no faster than 15mph so no speed issues but gaining lattitude. Could well be good for a long track FISH.

Only 2 days behind 2005 in named storms it turns out.

[summer blizzard]

97L now 50 percent.

Any model plots?

[summer blizzard]

97L now at 30% due to dry air by the looks of things.

98L now off the coast of Africa and at 10% but much further south than 97L so may make it to the promised land of the Carribean.

[summer blizzard]

..

Edited August 27, 2012 by summer blizzard

[summer blizzard]

..

Edited August 27, 2012 by summer blizzard

[summer blizzard]

Posted in wrong thread, apologies.

Edited August 27, 2012 by summer blizzard

[summer blizzard]

98L is now interesting me more.

Only at 20% now but only moving at 15mph and conditions are expected to improve.

Now at 35W so if we assume it does not develop before 60W then it could be a threat.

[summer blizzard]

98L now upto 40%.

[snowydog]

Interesting .... Can someone clue me in on how you guys determine whether the storm will develop? What conditions etc do you look at? I really don't know much. Just the basics. (warm sea temperatures, wind speed etc).

Wish I could read/understand weather models. Apart from A Level geography, I don't know much!

[summer blizzard]

Interesting .... Can someone clue me in on how you guys determine whether the storm will develop? What conditions etc do you look at? I really don't know much. Just the basics. (warm sea temperatures, wind speed etc).

Wish I could read/understand weather models. Apart from A Level geography, I don't know much!

There are a multitude of factors and only 15% of tropical waves actually develop on average.

1) Dry air (look at the moisture content of the surrounding location)

2) Speed (fast motion indicates high easterly and relative shear)

3) shear (Upper level lows can shred a storm)

4) Lattitude (further south means it will likely get further west)

5) Track (further west the higher the chance of landfall)

[snowydog]

There are a multitude of factors and only 15% of tropical waves actually develop on average.

1) Dry air (look at the moisture content of the surrounding location)

2) Speed (fast motion indicates high easterly and relative shear)

3) shear (Upper level lows can shred a storm)

4) Lattitude (further south means it will likely get further west)

5) Track (further west the higher the chance of landfall)

Thanks for that. I'm going to go and read up on what you've listed

[summer blizzard]

98L now at 60%.

Sattelite looks fairly good..

[Somerset Squall]

Now at 70%, though to my untrained eye, 98L isn't far off becoming a tropical depression pretty soon.

[Paranoid]

NHC have upped 98L to near 100%, so we should have TD12 or TS Leslie by the 1500GMT advisory.

Edited August 30, 2012 by Paranoid

[geoffw]

yep and 100% a fish

[geoffw]

but its likely to be the seasons 1st major cane

[summer blizzard]

Looking at the data it seems as though the MJO may be entering a less favourable phase soon (we want 8-1-2-3 - it is currently in phase 3) so there is a chance we may see more of a lull in development outside the Carribean however there is a wave coming off Africa in 1-2 days so it will be interesting to see what happens to this (it needs to be slow otherwise it may interact with Leslie's outflow).

[summer blizzard]

Another wave over the Cape Verde Islands at 40% (i forget the code).

[evil monkey]

Another wave over the Cape Verde Islands at 40% (i forget the code).

91L. The models are forecasting another FISH; as for intensity, who knows?

[summer blizzard]

92L has been declared, 10% chance but about to move into the Carribean.

[Coast]

Thus far, the 2012 Atlantic hurricane season that is about at its midpoint has seen 14 tropical storms, with seven strengthening to hurricane status. According to catastrophe modeling firm Risk Management Solutions (RMS), the current hurricane season has been active:

One of these hurricanes has become a major hurricane – Hurricane Michael, which intensified into a Category 3 hurricane on September 6, but only maintained that status for 6 hours. At this point (September 13) in 2012 the season is the second most active season (tied with 1936) since records began in 1851, in terms of the number of named storms. Only 2005 and 2011 had more named storms as of September 13.

Eight tropical storms formed in August, making August 2012 the most active August in terms of Atlantic basin tropical storm activity, tied with the 2004 season. As of September 13, the season is just over halfway through, and on average, are currently in the most active month– September 10 is officially classed as the peak of the hurricane season. Between 1950 and 2011 on average four tropical storms formed in September, with an average of five tropical storms forming in September between 1995 and 2011. (2004 had four tropical storms in September, and 2005 had five tropical storms in September—all of which strengthened to hurricanes.)

“Seasonal forecasts for 2012, issued at the beginning of August called for around 14 tropical storms in the Atlantic in 2012,†said Dr. Christine Ziehmann, director of Model Product Management at RMS. “The 2012 season is currently on track to exceed these forecasts, especially if September is typical of the 1995-2011 average.â€

A weak to moderate El Niño is forecast to develop during September, which has the potential to inhibit tropical storm development. However through the 2004 hurricane season a weak El Niño was prevalent, although there was still an above-average number of tropical storms, hurricanes, and major hurricanes—the season closing with 14 tropical storms, nine hurricanes and six major hurricanes.

http://www.insurance...9/14/263103.htm

[Coast]

Hurricane season outlook for the second half:

As tropical storm Nadine slowly winds down near the Azores islands, it appears that we’ll see a break in the action across the basin. The season is well ahead of climatology for this date, but will that trend continue?

We’ve already had 14 tropical storms, 8 hurricanes, and 1 major hurricane, but most signs point to a generally quieter period coming up compared to what we’ve seen so far.

Of course, a potent hurricane can still occur even during periods of below-average activity, so it’s definitely too early to dismiss the season!

The “Cape Verde seasonâ€, when long-lived storms form off the west coast of Africa and track across the deep Atlantic for 10-14 days, is nearing its climatological end. This year, that shouldn’t make a big difference, since we only had one storm briefly become a hurricane south of 25N (Ernesto in early August). All other hurricanes formed above 25N which is quite rare. In the 10 weeks or so remaining in the official hurricane season, most storms typically form in the western Caribbean, Gulf of Mexico, or off the U.S. East coast

The sea surface temperatures across the Caribbean and western Gulf of Mexico are just slightly above average, while the eastern Gulf of Mexico is slightly below average. Overall, these sea surface temperatures shouldn’t be a big factor.

However, two large-scale drivers of activity are the Madden-Julian Oscillation (MJO) and El Nino Southern Oscillation (ENSO), and both of these are heading toward unfavorable phases in the Atlantic.

In the diagram above, the phase (location around the globe) of the MJO is shown. The MJO can enhance or suppress disturbances over a large area for weeks at a time. It can be tracked around the world: the purple and red lines trace the observed location and strength of the MJO since August 10, and the green and yellow lines are forecasts starting on September 19. When the MJO is in phases 1-2, activity in the Atlantic typically picks up, and when it’s in phases 6-7, Atlantic activity is suppressed. In other phases, the effect is fairly neutral. As you can see, for at least the next two weeks, the MJO should act to suppress tropical activity in the Atlantic.

ENSO is another important ingredient in controlling relative activity levels in the Atlantic, and is governed by the warmth of the equatorial East Pacific ocean. When it’s warmer than normal, there’s an El Nino, and when it’s cooler than normal, there’s a La Nina.

La Nina is generally conducive for Atlantic activity, while El Nino is unfavorable (this is due to a complex feedback that increases the vertical shear over the deep tropical Atlantic during El Nino and decreases it during La Nina). In the figure shown above, a number of sophisticated models from around the world all predict El Nino conditions to dominate and persist through next spring (positive temperature anomalies in the equatorial East Pacific).

So, while we had an active streak since early August, it should slow down, but that doesn’t mean the season is over. Having slightly below average activity this time of year can still result in some powerful hurricanes, perhaps just not as many or maybe not as strong.

Season statistics so far

Accumulated Cyclone Energy (ACE) is a standard metric used for objectively measuring tropical cyclone activity. It’s doesn’t take into account exactly how many hurricanes form, or exactly how long a storm was a major hurricane, but rather it simply squares the wind speed of any storm exceeding 40mph at each 6-hour interval and adds them all up. Therefore, it’s possible that a very long-lived tropical storm could contribute more ACE than a short-lived low-end hurricane.

As of today, the ACE is 88.3, while the 1981-2010 average for this date is 69.9... that’s 126% of “normalâ€. By the end of the season, the median ACE wraps up at 92 (the mean is 104). So to even meet the median, we only need another 4 ACE units, which isn’t hard to do.

The seasonal forecast issued by Colorado State University predicts a total ACE of 99, while the nebulous seasonal forecast issued by NOAA predicts a 70% probability of the ACE falling in the 69–124 range. An ACE above 103 is considered to be “above normalâ€

http://www.washingto...6e190_blog.html

[JonMillar]

What is the prognosis for Invest 96L? Currently at 70% possibility of becoming a tropical storm in the next 48 hrs.

Edit: Found it

Another FISH!

Edited October 2, 2012 by JonMillar