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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I think this Winter Tallahassee will get snow flurries I can feel it!!!
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Quoting NRAamy:
LOL...Amy wearing a Polar Bear hide...and it's chapped...LMAO

why do I have visions of PETA hags getting their panties in a bunch?


Getting them in a bunch? Don't they tie them in knots and then put them on?
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Afternoon All.

Still going :-(
Heat Index: 101 °F

Relief in sight for Sunday? Let's hope it holds.
76° F | 56° F
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NOLA NWS Discussion

Previous discussion... /issued 516 am CDT Thursday Oct 15 2009/


Short term...
severe and heavy rain potential will be the main concerns this
afternoon and tonight...then the focus will turn to marine issues
related to strong winds and hazardous seas Friday into Sunday.
A nearly zonal flow pattern aloft will amplify through Friday as
an upper level ridge builds over western North America and a
series of shortwave troughs carves out a trough over eastern North
America. A strong cold front will push through the most of the
forecast area tonight...and the offshore coastal waters Friday
morning. There are several parameters coming together to support
isolated strong to severe thunderstorms and locally heavy rain due
to local training of heavy showers and thunderstorms.
Strong low
level convergence near and just ahead of the cold front and
divergence aloft will bring substantial synoptic scale lifting
starting in the northwest zones this afternoon then spreading
southeast across the remainder of the area during the evening.


Mav and met temperature and cloud cover guidance is showing very
warm and humid conditions due to breaks in clouds/partly sunny
skies and compressional heating ahead of the cold front. The
timing of the best lift may be a little past the time of best
heating except over the north and northwest...but there will
continue to be slight to moderate elevated instability for 50 to
100 miles behind the cold front. The low level westerly inflow and
bulk shear combined with the instability and larger scale lifting
should be support the slight risk of severe thunderstorms that is
outlooked by Storm Prediction Center for areas generally along and north of I-10 and
the tidal lakes. Storm motion and propagation vectors will be
favorable for back-building of thunderstorms...but the line should
be moving with the front. Could still see some isolated 2 to 3
inch rainfall amounts in a one to two hour period.


The severe threat and thunderstorm chances will decrease from the
north late in the evening and overnight as the cold front charges
towards the coast and coastal waters. Any lingering coastal showers
on Friday will end quickly during the morning...then much drier
air and cooler air...and decreasing cloud cover will be the rule.
Friday night will see the coolest temperatures of the season with
widespread middle 40s to middle 50s expected for lows under mostly clear
skies. It will become breezy on the South Shore and in coastal
sections and north winds increase.


Long term...
dry and cool weather will prevail Saturday through Monday. A
secondary strong shortwave trough and reinforcement of cooler air
with breezy conditions are expected on Saturday and Saturday
night. Highs on Saturday are expected to only be in the middle 60s
with a period of partly to mostly cloudy skies possible due to
strato-cumulus. Any cloud cover should clear out Saturday night
which will lead to even colder temperatures more typical of winter
averages down in the 40s over most areas. The ensemble MOS
guidance is showing lows in the middle to upper 30s over kbtr and
kmcb. Am not forecasting that cold yet...but will have to see if
that trend holds in the next couple model runs.
Member Since: July 3, 2005 Posts: 426 Comments: 128668
LOL...Amy wearing a Polar Bear hide...and it's chapped...LMAO

why do I have visions of PETA hags getting their panties in a bunch?
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Lafayette, Purdue University Airport
Lat: 40.43 Lon: -86.93 Elev: 623
Last Update on Oct 15, 11:54 am EDT

Overcast with Haze

42 F
(6 C)
Humidity: 82 %
Wind Speed: NE 9 MPH
Barometer: 29.91" (1013.0 mb)
Dewpoint: 37 F (3 C)
Wind Chill: 36 F (2 C)
Visibility: 2.50 mi.


Hey Storm
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Quoting Floodman:


Well, I'm with you...Al Baby likes to give you only the data that supports his position and then tell you that yes, Virginia, the sky IS falling...

It's like watching a documentary on UFOs where the opposing, skeptical view, is not represented at all; it makes you think that they'll be landing any minute now...that's crap science, no matter how you slice it


All in favor - AYE!
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The Brown Pelican's Return to Coastal Louisiana - Part One
The Brown Pelican and Louisiana History
The Brown Pelican and Louisiana History

The brown pelican (Pelecanus occidentalis) has a storied connection to Louisiana. From Iberville's first coasting of the Gulf of Mexico's shores in search of the Mississippi's mouth in 1699, journals kept by those in his company recorded the populous colonies of the birds they encountered. After returning to France, Iberville would captain a ship christened The Pelican back to the New World in 1704, carrying with him some 24 "well-bred" girls to the burgeoning colony of Louisiana in hopes that they would provide an incentive for permanent settlements.

State of Louisiana Seal: "Union, Justice and Confidence"It is said by some that William Claiborne, the territory's first governor after the Louisiana Purchase in 1803, was the first to suggest that the brown pelican appear on Louisiana's seal. No matter the rightful originator of the notion, a pelican feeding its young could be found on the seal as early as 1804. As for the bird itself, no less an authority than the painter and naturalist John James Audubon would describe the pelican as "one of the most interesting of our American birds", waxing rhapsodic as he went on to describe the species' feeding habits in his journal:

Look at them as they fly over the bay; listen to the sound of the splash they make as they drive their open bills, like a pock-net, into the sea, to scoop up their prey; mark how they follow that shoal of porpoises, and snatch up the frightened fishes that strive to escape from them. Down they go, again and again. What voracious creatures they are!


Member Since: July 3, 2005 Posts: 426 Comments: 128668
Quoting tornadodude:


haha thanks, so the blog is fairly dead today


LOL...Amy wearing a Polar Bear hide...and it's chapped...LMAO
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Quoting NRAamy:
Jerry..I guess the moral of this story is...you can't trust what you hear on the news....and...Al Gore still chaps my hide...

;)


Well, I'm with you...Al Baby likes to give you only the data that supports his position and then tell you that yes, Virginia, the sky IS falling...

It's like watching a documentary on UFOs where the opposing, skeptical view, is not represented at all; it makes you think that they'll be landing any minute now...that's crap science, no matter how you slice it
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Quoting Floodman:


Per the latest populations studies run by the Canadians and the Europeans, only one subpopulation of the bears is increasing of the 19 recognized sub populations, as opposed to 2 on the increase just 4 years ago., The rest of these populations are in decline. The population that is increasing is in Canada and is only doing so becasue they are coming in off the ice (where it exists) and scrounging around human settlements.
The studty from 4 years ago found that two sub populations were increasing and that 10 were in decline, 5 precipitously. The data on the remaining populations was insufficient to make a clear determination, much the same as the latest census information, where 6 of the 19 populations were in areas where data collection was difficult due to terrain, inaccessibility, etc. It is the feeling of the members of the study that based on the limited data that was collected the remaining populations would be split along the same statistical lines as the the rest, with the majority of the subgroups in decline...

Smoke that, for what it's worth


its kinda like brown pelicans, endangered in louisiana, i see flocks of sometimes twenty or more on the bay here in nw fla on my way to work. also black bear are almost gone in the smokey mts but here in nw fla they are ok population-wise i think. a thing can increase in population in one area while really going extinct as a species.
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MLB is in trouble trying to play baseball in the NE this weekend.
Could even be some Snow possible!
Member Since: September 2, 2007 Posts: 178 Comments: 20443
just read about this. Pretty awsome..

catatumbo lightning
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The Right Stuff


By Keith Cowing on October 20, 2008 10:18 AM 11 Comments

NASA Michoud Assembly Facility's Hurricane Gustav Rideout Crew Honored with Director's Commendation Award

"David King, director of NASA's Marshall Space Flight Center in Huntsville, Ala., has awarded the Director's Commendation to members of the Hurricane Gustav rideout crew at the Michoud Assembly Facility in New Orleans for their outstanding effort in planning and implementing emergency operations to protect the facility. As Hurricane Gustav approached the Gulf Coast, the 51-person rideout crew stayed on the Michoud site to secure the facility, monitor the hurricane and ride out the storm. Its members include NASA civil service, Lockheed Martin contractor employees and Coastal International Security personnel."

Editor's note: I was at MAF a matter of weeks after Katrina. I saw things in the faces of the people who worked there that I never expected to see. How and why they do things harkens back to another time. This is not the first time that these folks have taken significant personal risks to preserve critical aspects of America's human space flight program. They do so in a no-nonsense fashion - and when you ask them why, as I did, they say things such as "because its my job, sir". To those of you sitting behind desks at NASA: think of that later today when you stop what you are doing simply because your car pool is about to leave. During Katrina these people stayed on the job as their families and homes risked - or actually experienced - utter destruction. And then they lived at work for weeks sleeping on cots.
Member Since: July 3, 2005 Posts: 426 Comments: 128668
Quoting tornadodude:


haha thanks, so the blog is fairly dead today


Agreed - why isn't anyone talking about the freaking Epac wave or Lupit? What the hell kind of name is Lupit anyway?
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Quoting presslord:
...definitely a creepy pattern developing...


rough winter ahead?
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...definitely a creepy pattern developing...
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Quoting NRAamy:
good one, dude...

:)


haha thanks, so the blog is fairly dead today
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good one, dude...

:)
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Seismic Monitor

AOI

AOI

Humor in Comments
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting NRAamy:
Jerry..I guess the moral of this story is...you can't trust what you hear on the news....and...Al Gore still chaps my hide...

;)


a Polar Bear hide...?
Member Since: Posts: Comments:
Jerry..I guess the moral of this story is...you can't trust what you hear on the news....and...Al Gore still chaps my hide...

;)
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This area i pointed out yesterday looks like it might be in for some trouble today.








Looks like the first NorEaster of the year!
Member Since: September 2, 2007 Posts: 178 Comments: 20443
Quoting NRAamy:
saw Al Gore get questioned last night...it seems the population of the polar bears is BIGGER THAN EVER....it's GROWING...not diminishing....

so stuff that in your Prius and smoke it, Al.....


Per the latest population studies run by the Canadians and the Europeans, only one subpopulation of the bears is increasing of the 19 recognized sub populations, as opposed to 2 on the increase just 4 years ago. The rest of these populations are in decline. The population that is increasing is in Canada and is only doing so becauae they are coming in off the ice (where it exists) and scrounging around human settlements.
The study from 4 years ago found that two sub populations were increasing and that 10 were in decline, 5 precipitously. The data on the remaining populations was insufficient to make a clear determination, much the same as the latest census information, where 6 of the 19 populations were in areas where data collection was difficult due to terrain, inaccessibility, etc. It is the feeling of the members of the study that based on the limited data that was collected the remaining populations would be split along the same statistical lines as the the rest, with the majority of the subgroups in decline...

Smoke that, for what it's worth
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Quoting RitaEvac:
Hazel hit the Carolinas today in 1954



I was raised hearing Hazel horror stories...thanks for pointing that out...
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Anyone else notice the GFS, EMCWF and CMC among some others are picking the EPAC wave to become a strong hurricane to curve around a ridge into Baja/Mazatlan?

System looks like it's organizing better, too with some banding features and good convection lately
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Quoting PensacolaDoug:
But no snow in Florida.....maybe this'll be the year.
It snowed in NOLA on Dec 10 last year. Earliest snowfall ever recorded there.
This year will be a lot cooler than in normally is in Florida, and there will also be more precipitation than normal so flurries won't be that hard to come by.
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Quoting NRAamy:
saw Al Gore get questioned last night...it seems the population of the polar bears is BIGGER THAN EVER....it's GROWING...not diminishing....

so stuff that in your Prius and smoke it, Al.....


Polar Bear population
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52. IKE
48 hours on the 12Z GFS....

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saw Al Gore get questioned last night...it seems the population of the polar bears is BIGGER THAN EVER....it's GROWING...not diminishing....

so stuff that in your Prius and smoke it, Al.....
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Quoting timtrice:
Arctic ice to vanish in summer, report says


Poor Santa Claus
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Hazel hit the Carolinas today in 1954

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Arctic ice to vanish in summer, report says
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Quoting presslord:



Dude! Check out the Portlight WU featured Blog...it'll 'splain it all....PLEASE join us !!!!!!!!!!!!!!


Ok, not sure if I can make it, I have an exam at 6:30 :(
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..I should shower and do my Hair before the call I guess..
Member Since: July 3, 2005 Posts: 426 Comments: 128668
Quoting Bonedog:
Already snowing by me =)

Hewitt, NJ 1305ft and WE HAVE SNOW!!!

Earliest I can remeber. NWS posted a winter weather advisory for me. 1 to 4 inches =)

LET IT SNOW
LET IT SNOW
LET IT SNOW


It was snowing in Northern Indiana this morning too!
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Quoting tornadodude:


Hey, what exactly is the conference call, I might do it if I know what it is, sorry if this is a dumb question, I was just confused :P



Dude! Check out the Portlight WU featured Blog...it'll 'splain it all....PLEASE join us !!!!!!!!!!!!!!
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Already snowing by me =)

Hewitt, NJ 1305ft and WE HAVE SNOW!!!

Earliest I can remeber. NWS posted a winter weather advisory for me. 1 to 4 inches =)

LET IT SNOW
LET IT SNOW
LET IT SNOW
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Quoting presslord:
Big news!!!!!

Dr. Masters is apparently pretty scared...

Not wanting, I suppose, to have to endure the pain of another me-in-a-dress picture...

...he has just informed me that he will be joining us tonight on the Portlight conference call...

details in post # 26 here on Dr. Masters blog...


Hey, what exactly is the conference call, I might do it if I know what it is, sorry if this is a dumb question, I was just confused :P
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Zoomiami..so waiting for it! And you? :)
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Big news!!!!!

Dr. Masters is apparently pretty scared...

Not wanting, I suppose, to have to endure the pain of another me-in-a-dress picture...

...he has just informed me that he will be joining us tonight on the Portlight conference call...

details in post # 26 here on Dr. Masters blog...
Member Since: August 13, 2007 Posts: 0 Comments: 10492
Why does snoop dog need an umbrella......?





fo drizzle....

slow blog day xD
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Quoting IKE:


Nope....not gonna touch this one. Nope....not gonna do it.




Nope....not gonna touch this one. Nope....not gonna do it.


Ike,your killing,I still haven't stopped laughing.
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Quoting PensacolaDoug:
But no snow in Florida.....maybe this'll be the year.
It snowed in NOLA on Dec 10 last year. Earliest snowfall ever recorded there.


I'd say this year presents a decent chance for it anyway, better chance than most other years probably
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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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