Outlook for the remainder of hurricane season

By: Dr. Jeff Masters , 1:18 PM GMT on October 15, 2009

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Atlantic tropical cyclone activity finishes its peak phase in mid-October, and takes a major downturn after about October 20 (Figure 1). Since the current active hurricane period began in 1995, the last half of October through the end of hurricane season has given birth to an average of 1.7 named storms, 0.8 hurricanes, and 0.3 intense hurricanes. These numbers are nearly double the long-term climatological averages for the past 100 years. So far this year, only one tropical storm has hit the U.S.--Tropical Storm Claudette. If no more tropical storms make landfall in the U.S., it will be the first year since 1993 to see only one tropical storm hitting the U.S.


Figure 1. Atlantic hurricane season activity over the past 100 years.

Late October and November storms tend to form from tropical waves that come off the coast of Africa, or from the remains of old fronts that push off the coast of the U.S. As we can see from the track plot of all last half of October storms (Figure 2), there is a lot of activity during the period, but relatively few storms form out near the African coast. The water temperatures off the coast of Africa are starting to cool and be marginal for hurricane formation, and the African Monsoon is waning, leading to fewer African waves coming off the coast. Wind shear is also starting to increase, as part of its normal fall cycle.

Climatology of late-season major hurricanes
Let's examine the possibilities of getting a late-season major hurricane, since those are the storms we care most about. Since 1960, there have been twelve hurricanes that have existed as major Category 3 or higher storms after October 15. Eight of these have occurred since 1995: Omar of 2008 (Cat 4, Lesser Antilles), Paloma of 2008 (Cat 4, Cayman Islands and Cuba), Wilma of 2005 (Cat 4, Mexico; Cat 3, SW Florida), Beta of 2005 (Cat 3, Nicaragua), Michelle of 2001 (Cat 4, Cuba), Lenny of 1999 (Cat 4, northern Lesser Antilles), Mitch of 1998 (Cat 5, Honduras), and Lili of 1996 (Bahamas, Category 3). The other four were Joan of 1988 (Cat 4, Nicaragua), Kate of 1985 (Cat 3, Gulf of Mexico), Ella of 1962 (Cat 3, west of Bermuda), and Hattie of 1961 (Cat 4, Belize). Wilma of 2005 was the only major hurricane since 1960 to hit the U.S. after October 15. The highest risk region for late season major hurricanes is the Western Caribbean, along the coasts of Nicaragua, Honduras, Belize, Mexico, and Cuba. So, we can say with high confidence that most of the U.S. coast can relax. Only the west coast of Florida, Florida Keys, and South Florida need to still be concerned about the possibility of a major hurricane. The Lesser Antilles Islands, Puerto Rico, and Hispaniola are also at low risk for a major hurricane the remainder of the season.



Figure 2. Tracks of all tropical storms and hurricanes since 1851 that formed October 16-31.

Sea Surface Temperatures
Sea Surface Temperatures (SSTs) are 0.5 - 1.5°C above average over the Western Caribbean and Gulf of Mexico (Figure 3), the primary formation areas for late October storms. So, there is still plenty of fuel for a major hurricane to form. Note also the tongue of warmer than average SSTs extending out into the Pacific Ocean from the coast of South America, the signature of weak El Niño conditions.


Figure 3. Sea Surface Temperature (SST) departure from average for October 15. Image credit: NOAA.

Wind shear
Wind shear is usually defined as the difference in wind between 200 mb (roughly 40,000 foot altitude) and 850 mb (roughly 5,000 foot altitude). In most circumstances, wind shear above 20 knots will act to inhibit tropical storm formation by tearing a storm apart. Wind shear 10 knots and lower is very conducive for tropical storm formation.

The jet stream in mid-October is more active and extends further south, which brings higher levels of wind shear to the Atlantic. The more active jet stream also acts to recurve storms more quickly. Any system penetrating north of about 20 degrees north latitude we can expect to recurve quickly to the north and northeast this late in the season. The most recent 16-day forecast from the GFS model predicts a period of high wind shear over the tropical Atlantic over the next ten days (Figure 4). Beginning on October 25, wind shear is expected to fall again over the Western Caribbean, and we need to be alert for tropical storm formation then. Indeed, the latest run of the GFS model is predicting a large area of surface low pressure will form in the Western Caribbean during the last week of October, an indication that hurricane season may not be over yet.

El Niño
El Niño conditions, which typically bring higher wind shear to the Atlantic and interfere with hurricane formation, continue to be present in the tropical Eastern Pacific. It is probably the case that some of this year's inactivity can be attributed to El Niño. However, as I discussed in a post earlier this year, El Niño events that warm the central Pacific more than the eastern Pacific (called "modiki" El Niño events), tend to bring less wind shear to the Atlantic. In recent weeks, El Niño conditions in the Eastern Pacific have trended more towards a "modiki" type event, with a large amount of warming in the Central Pacific. This shift in the El Niño may bring lower wind shear to the Atlantic over the final month of hurricane season.


Figure 4. Wind shear forecast for October 23, 2009, as produced by the 00 UTC run on October 14, 2009 made by the GFS model. Wind shear below about 8 m/s (roughly 15 knots, red colors) is typically needed to allow tropical storm formation. There aren't too many red-colored areas over the prime breeding grounds for tropical storms in the Atlantic over the next ten days in this forecast.

Summary
Given how quiet the tropics are at present, and the forecast of a high wind shear regime lasting until October 25, I doubt any tropical storms will form over the next ten days. If we do get something, it would probably be in the middle Atlantic between Bermuda and the Azores, far from land. However, I am still wary of the possibility of a hurricane in the Caribbean the last week of October or in November this year. There is evidence that the Atlantic hurricane season is starting earlier and ending later in recent decades. Dr. Jim Kossin of the University of Wisconsin published a paper in 2008 titled, "Is the North Atlantic hurricane season getting longer?" He concluded that yes, there is a "apparent tendency toward more common early- and late-season storms that correlates with warming Sea Surface Temperature but the uncertainty in these relationships is high". We had two major hurricanes in the Caribbean after October 15 last year, and I give a 60% chance that we'll get a named storm in the Caribbean before hurricane season ends on November 30. Hurricane season is not over--it's just in hibernation.

Happy Valley to become Yucky Valley
Winter is fast approaching, and the season's first major snowstorm for the U.S. East Coast is coming this weekend, according to the wunderblog of Wunderground's Dr. Rob Carver. Conditions will be particularly nasty on Saturday in Happy Valley, where Penn State is situated. The surrounding hills may get 4 - 12 inches of snow, and rain mixed with snow with 36°F temperatures are expected for Saturday's Penn State - Minnesota game. Ugh, winter! I'll have a forecast for the coming winter in a post sometime in the next week.

The Senate has not yet voted on the proposal to cut NOAA funding. I will post a report when the vote occurs.

Jeff Masters

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237. Skyepony (Mod)
atmo Please refer here..

Anthropogenic Effects on Tropical Cyclone Activity
(Revised January, 2006)

Kerry Emanuel
Program in Atmospheres, Oceans, and Climate Click Here to return to Kerry Emanuel’s Home page.
Massachusetts Institute of Technology
Cambridge, MA 02139, USA

Part I: Frequently asked questions

Part II: Essay



I. Frequently Asked Questions about Global Warming and Hurricanes



1.) Q: Is global warming causing more hurricanes?

A: No.
The global, annual frequency of tropical cyclones (the generic, meteorological term for the storm that is called a tropical storm or hurricane in the Atlantic region) is about 90, plus or minus 10. There is no indication whatsoever of a long-term trend in this number.
Member Since: August 10, 2005 Posts: 161 Comments: 37335
Quoting all4hurricanes:


Nothing good can come of these


nothing good at all..
Member Since: June 28, 2006 Posts: 24 Comments: 8201


Nothing good can come of these
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Causeway (bridge ~12 feet above sea level) showing on the radar again. And only the southern end, again. Some 40 miles from the radar site.

Member Since: August 16, 2007 Posts: 6 Comments: 12461
Sarasota Hot and sunny Too
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Quoting atmoaggie:

Kick-a__!
And Linux experience alone is resume material in this field. (I you didn't officially have any)

I know we would not hire anyone with no Linux experience, given an applicant that had some.


yeah, it is a dream job for me, they are getting me books on how to use Linux, and will also give me a book about maintaining web pages. So, when I read the books, I get paid (:

Come on, how many freshman get their own office? lol
Member Since: June 28, 2006 Posts: 24 Comments: 8201
To atmoaggie,..I'm puzzled by your choice of words,...specifically,.."IF" there is stratospheric cooling. In my work as an Engineer, when ever two groups (unknown to each other) measure a phenomenon,...get the same results, and arrive at those same results by two different measurement methods,...that usually means the data is good, and the phenomenon is "genuine". The CO2 models predicted that greater CO2 concentration would cool the Stratosphere; less leakage to space, warmer down low,..cooler up high (First Law of Thermodynamics). There were direct measurements taken of the drop in temp in the Stratophere, -.6 deg C. Later,...NASA Engineers noticed that satellites, "parked at a given altitude orbit" were not experienceing the usual rate of orbit decay,...the cause was traced to lower stratosperic temperature,...resultant increase in air density,..and contraction of the Stratosphere,...which lowered the drag on the satellites,...letting them stay in orbit longer. I'd say,..since we have mutually coroborative(sp?) sets of data,...THE STRATOSPHERE HAS COOLED,...its not "IF",....its "IS".

Quoting atmoaggie:

Right. That does make sense if it all comes to fruition...under the same mechanism I meant when saying that CAPE would be on the rise if there were strat cooling. Same mechanics as hot towers...

I think you worded it fine.
Quoting tornadodude:

Alright, here is the scoop in my new job.

It is located on the 4th floor of the Civil building at Purdue.

It pays well.

I work with the exact same software and data sources that the SPC uses and I have 5 computers with 2 monitors a piece to use, plus two other computers with a 54in tv screen for each.

I use Linux most of the time.

There is a good chance that I will be getting my own office too (:

Also, I manage 4 computer displays in the hallway that keep people up to date on the weather and am responsible for the content of them.

I am super excited xD

Kick-a__!
And Linux experience alone is resume material in this field. (I you didn't officially have any)

I know we would not hire anyone with no Linux experience, given an applicant that had some.
Member Since: August 16, 2007 Posts: 6 Comments: 12461

Alright, here is the scoop in my new job.

It is located on the 4th floor of the Civil building at Purdue.

It pays well.

I work with the exact same software and data sources that the SPC uses and I have 5 computers with 2 monitors a piece to use, plus two other computers with a 54in tv screen for each.

I use Linux most of the time.

There is a good chance that I will be getting my own office too (:

Also, I manage 4 computer displays in the hallway that keep people up to date on the weather and am responsible for the content of them.

I am super excited xD
Member Since: June 28, 2006 Posts: 24 Comments: 8201
Quoting winter123:


Actually, if it's strong it will be pulled north of the phillipenes. I'd say they vote for that.

That is what I'm thinking. Cheer for strong as long as you're sure it misses...that is if you have interests in the Philippines (I don't think they need the rain)
Member Since: August 16, 2007 Posts: 6 Comments: 12461
i really hate it when people try to politisize weather things like global climate change. just because polar bears are growing in population in one out of 19 colonies does NOT prove climate change doesnt exist.

all it proves is that some people on here would rather start political agruements just for the sake of politics, rather than for the sake of intelligent discussion.
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Quoting atmoaggie:
I think the Philippines would gladly take the lower end of the intensity forecasts...unless that means it is a slow-moving rainmaker. Pick yer poison: Slow-moving rainmaker weaker storm, or quicker nasty-typhoon.





Actually, if it's strong it will be pulled north of the phillipenes. I'd say they vote for that.
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Looks like Baja California could see Major Hurricane Rick in 5-7 days.
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86F in Lufkin, 62F at Dallas...

Member Since: August 16, 2007 Posts: 6 Comments: 12461
It looks like TS 22 (Lupit) will make landfall in Northern Luzon as a cat. 4 typhoon, although right now it looks too far away for us to be certain. The last time such a strong typhoon hit Luzon was in November 2006, when Typhoon Durian hit southern Luzon. At least 720 people in the Philippines perished from that storm.
Member Since: August 30, 2008 Posts: 8 Comments: 2835
And the GFS is still doing the Viagra-MJO forecasts (in 2 more days it may need to see it Doctor...)



If that really happens, I suggest everyone take 3 right-hand turns in their vehicles for a few days in lieu of lefts. Don't want to get anything started...
Member Since: August 16, 2007 Posts: 6 Comments: 12461
221. auburn (Mod)
Quoting pearlandaggie:
214. 113 cu. ft of He can lift 7.1 lbs, so 2000 cu. ft can lift about 125 lbs. however, the "container" will be heavier, so the balloon will lift 125lbs. minus the weight of the balloon. hth.......


Thanks...Trying to figure out how high it could have lifted the little boy in Co...just in case he did fall out of the Balloon
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Quoting winter123:
is there anywhere east of the miss. river with sun right now?? wow.



I'm in St, Petersburg and its Sunny with blue skies with a couple of clouds here and there.
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gfs calls for development of an african wave in 7ish days, then some type of hybrid storm off georgia soon after that, nearly stationary. Granted, this is way too far off to take as accurate, but something to watch for, anyway... ill be back, whenever.
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I think the Philippines would gladly take the lower end of the intensity forecasts...unless that means it is a slow-moving rainmaker. Pick yer poison: Slow-moving rainmaker weaker storm, or quicker nasty-typhoon.



Member Since: August 16, 2007 Posts: 6 Comments: 12461
214. 113 cu. ft of He can lift 7.1 lbs, so 2000 cu. ft can lift about 125 lbs. however, the "container" will be heavier, so the balloon will lift 125lbs. minus the weight of the balloon. hth.......
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Quoting rocketboy105:
What was Kerry Emanuel being scolded for? He has readily stepped up when new data came in,..and said they were rethinking various things. For ex. the verdict on whether Global Warming will cause "more storms" is still out. There is even the "possiblity" that Climate Change could cause fewer storms,...but the ones that do form,...are,..and will be more instense. There seem to be off-setting factors that have yet to be fully teased out. More clouds,...more or less wind shear,..higher or lower trade winds with their resultant heat soak effect.

Stay tuned I guess. Speaking of which TS 22 in the NorthWest Pacific seems to be reving up. Conditions look ldeal for a rapid intensification. High TCHP,...29 deg C temp,...and low wind shear. As fun as they are to watch and track,..I do wish it would miss the Philipeans,..they've been through enough this year.


Honestly, I don't remember exactly what the premise of that one presentation was (I saw dozens that week over 4 days). I do remember that he heavily relied on the last 100 years of TC records to build a barely-there trend in the talk. After which, Landsea busted his chops on it and then Gray took his turn.

Building a set of conclusions about the future based on the last 100 years of TC obs is nonsense given the changes in observation methods over that time period...I have to agree with Landsea on that.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
TD 20E on NHC site. Might be the next Major in the EP.
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214. auburn (Mod)
2000 cu ft of helium....how much weight can it lift?I would think around 100 lbs???anyone know??
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is there anywhere east of the miss. river with sun right now?? wow.

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Quoting atmoaggie:

Right. That does make sense if it all comes to fruition...under the same mechanism I meant when saying that CAPE would be on the rise if there were strat cooling. Same mechanics as hot towers...

I think you worded it fine.
Thank you. Your input on weather is always appreciated here.
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quite an impressive maritime storm... the noreaster will probably look similar when it gets up there.

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Quoting P451:
TD20? It's listed as 20E on the SSD floater page.
Is this the remains of 92L?

Looks very healthy.



Yes, i believe it is the remnants of 92l, and possibly even henri, which hit beleze a couple days ago.
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Quoting winter123:


Wait.... parma gone?? I figured it would just keep circling the globe indefinitely and stalling over random land masses.


Parma and Karen xD
Member Since: June 28, 2006 Posts: 24 Comments: 8201
Quoting P451:
TD20? It's listed as 20E on the SSD floater page.
Is this the remains of 92L?

Looks very healthy.



20E as in TD 20 in the Eastern Pacific. This was 92L in the Atlantic.
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Quoting Skyepony:
Parma is gone. 93E is pulling together..May move a little closer to & rain on Central America some, then expected to turn left & not make landfall in the next 5 days. Someone name 22W already..

93E



22W



Wait.... parma gone?? I figured it would just keep circling the globe indefinitely and stalling over random land masses.
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204. IKE
Quoting CaicosRetiredSailor:
Interesting photo:




When the Heene family aren't chasing storms, they devote their time to scientific experiments that include looking for extraterrestrials and building a research-gathering flying saucer to send into the eye of the storm.

http://abc.go.com/shows/wife-swap/episode-guide/heenesilver/161743?page=2


My wife remembers this family...she just recently watched the episode.
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Interesting photo:




When the Heene family aren't chasing storms, they devote their time to scientific experiments that include looking for extraterrestrials and building a research-gathering flying saucer to send into the eye of the storm.

http://abc.go.com/shows/wife-swap/episode-guide/heenesilver/161743?page=2
Member Since: July 12, 2007 Posts: 0 Comments: 5996
201. xcool


hi all!!@!
Member Since: September 26, 2009 Posts: 2 Comments: 15620
What was Kerry Emanuel being scolded for? He has readily stepped up when new data came in,..and said they were rethinking various things. For ex. the verdict on whether Global Warming will cause "more storms" is still out. There is even the "possiblity" that Climate Change could cause fewer storms,...but the ones that do form,...are,..and will be more instense. There seem to be off-setting factors that have yet to be fully teased out. More clouds,...more or less wind shear,..higher or lower trade winds with their resultant heat soak effect.

Stay tuned I guess. Speaking of which TS 22 in the NorthWest Pacific seems to be reving up. Conditions look ldeal for a rapid intensification. High TCHP,...29 deg C temp,...and low wind shear. As fun as they are to watch and track,..I do wish it would miss the Philipeans,..they've been through enough this year.

Quoting atmoaggie:

Good. I haven't seen much Carnot in here.

Cooling of the stratosphere would increase CAPE for severe weather outbreaks, too.

Problem with the TC intensity is Emanuel has rather completely disregarded anything thing that theoretical warming might introduce that disrupts or hinders the heat engine. More shear, for example.

Emanuel has done a lot of work in the realm of TCs and climate change, but is at odds with a lot of his peers and mentors, too. You should have seen his face when Bill Gray (his former PhD adviser) told him "You know better and frankly I am disappointed in you" in front of ~600 folks at the AMS meeting a couple of years ago immediately following one of Emanuel's presentations (I was sitting behind Gray).
Quoting Magicchaos:


Rain with snow mixing in tonight, tomorrow, and Sunday. Looks like little or no accumulation though.


ah alright, pretty much more northeast of you?
Member Since: June 28, 2006 Posts: 24 Comments: 8201
Quoting tornadodude:


Hey, you getting any snow today?


Rain with snow mixing in tonight, tomorrow, and Sunday. Looks like little or no accumulation though, maybe a coating on the grass it seems.
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197. IKE
Heard on MSNBC...reporter said..."doesn't look good at this time."(about the child).
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TD 20E = 92L in the Pacific..
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Richard Heene
Father of Falcon Heene
storm chaser - published in Weather Digest
also appeared on "Wife Swap"

Google or YouTube for background

hmmmm....
Member Since: July 12, 2007 Posts: 0 Comments: 5996
Quoting hydrus:
If you have a moment, please read the post #177 and tell me if you understand what I meant. I did not know how else to word it.

Right. That does make sense if it all comes to fruition...under the same mechanism I meant when saying that CAPE would be on the rise if there were strat cooling. Same mechanics as hot towers...

I think you worded it fine.
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Quoting Magicchaos:
In case it wasn't mentioned:

invest_RENUMBER_ep932009_ep202009.ren

TD 20 in Eastern Pacific from 2:38PM


Hey, you getting any snow today?
Member Since: June 28, 2006 Posts: 24 Comments: 8201
In case it wasn't mentioned:

invest_RENUMBER_ep932009_ep202009.ren

TD 20 in Eastern Pacific from 2:38PM


Advisory at 5PM
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Quoting IKE:



It's on CNN...Headline News...MSNBC...FOX...

I had TWC on and they had continuous coverage on it there too. The boy wasn't inside it when it landed at around 3:40. They still have it on the TWC.
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Quoting atmoaggie:

Tim, this place is usually kept in a kid-friendly language sort of way...
If you have a moment, please read the post #177 and tell me if you understand what I meant. I did not know how else to word it.
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Post 184 - c'mon man, please keep it clean.
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Tim, this place is usually kept in a kid-friendly language sort of way...
Member Since: August 16, 2007 Posts: 6 Comments: 12461
Member Since: June 28, 2006 Posts: 24 Comments: 8201

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

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