Sean, rare Mediterranean hybrid, and AK superstorm forms; quakes and tornadoes in OK

By: Dr. Jeff Masters , 3:52 PM GMT on November 08, 2011

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Subtropical Storm Sean formed this morning between Bermuda and the Bahamas. Sean's formation brings this year's tally of named storms to eighteen, tying 2011 with 1969 as the 6th busiest Atlantic hurricane season since record keeping began in 1851. Only 2005, 1933, 1995, 1887, and 2010 have had more named storms. However, 2011 has had an unusually low percentage of its named storms reach hurricane strength. We've had an average number of hurricanes--six--meaning that only 33% of this year's named storms have made it to hurricane strength. Normally, 55 - 60% of all named storms intensify to hurricane strength in the Atlantic. There have been three major hurricanes in 2011, which is one above average, and the total Accumulated Cyclone Energy (ACE)--a measure of the destructive potential of this season's storms--has been about 20% above average. The rare combination of near-record ocean temperatures but unusually dry, stable air over the Atlantic is no doubt at least partially responsible for the unusually high count of named storms, but near-average number of hurricanes and ACE.


Figure 1. The subtropical disturbance that became Subtropical Storm Sean, as seen at 1 pm EST November 7, 2011. Image credit: NASA.

Infrared satellite loops reveal that Sean has developed a respectable amount of heavy thunderstorm activity near its center that is increasing in intensity and areal coverage. While the low-level circulation center is exposed to view, a band of thunderstorms is trying to wrap around and close of the center. If this occurs, more substantial strengthening can occur, since the center will be walled off from the dry air that is currently interfering with development. Bermuda radar shows weak rain bands from Sean rippling across the island, with the strongest rain showers well to the island's southwest. Sustained winds at the Bermuda airport have been under 30 mph this morning. Sustained winds near tropical storm force were occurring this morning at buoy 41048, about 300 miles west of Bermuda. Winds at the buoy were 38 mph, gusting to 47 mph at 6:50 am EST. Strong upper-level winds out of the west are creating about 20 knots of wind shear over Sean, which is low enough to allow some slow development. Sean is a relatively shallow storm, and the tops of its thunderstorms extend up only to about the 300 mb level. Normally, a tropical storm extends up to about 200 mb. The shallow nature of Sean's thunderstorms mean that the storm is less vulnerable to wind shear than normal, since the storm is not feeling the strongest winds aloft. Ocean temperatures are near 26.5°C (80°F), which is right at the boundary of being warm enough to support tropical storm formation.

Forecast for Sean
Sean will drift slowly west or northwest today and Wednesday. The latest SHIPS model forecast predicts wind shear will remain about where it is now through Thursday morning, which should allow Sean to slowly intensify to a 50 mph storm. If Sean can make the transition to a fully tropical storm, more significant intensification can occur. The computer models show little or no development of Sean, with none of our reliable models predicting it will become a hurricane. Bermuda is the only land area that need concern itself with Sean, as a trough of low pressure is expected to absorb the storm on Thursday and lift it quickly to the north or northeast. The center of Sean could pass close enough to Bermuda to bring the island heavy rain squalls and sustained winds of 40 - 45 mph on Thursday and Friday. NHC is giving a 28% chance that Bermuda will receive tropical storm-force winds of 39 mph. High wind shear should destroy Sean on Friday.


Figure 2. MODIS image of the hybrid low named "Rolf" in the Mediterranean Sea at 10:30 UTC November 8, 2011. Image credit: NASA.

Unusual tropical storm-like low forms off coast of France
An unusual hybrid low pressure system has formed in the Mediterranean Sea, about 100 miles south of the coast of France. The low began as an extratropical storm named "Rolf", but has stalled out over the relatively warm waters of the Mediterranean over the past two days, and has acquired tropical characteristics. Heavy thunderstorms have built over the northeast portion of the low, and the storm has a symmetric spiral shape with a cloud-free center, like a tropical storm. The Navy is calling this system Invest 99L. The National Hurricane Center is not responsible for the Mediterranean Sea, so they are not issuing any products for 99L. NOAA's Satellite and Information Service (NESDIS) is giving 99L a tropical classification based on its satellite presentation, with winds in the 40 - 45 mph range. French radar shows heavy rains from 99L are beginning to affect Southeast France and the island of Corsica. The Lion Buoy, located about 100 miles to the west of the center of 99L, recorded sustained winds of tropical storm force, 40 mph, at 00 UTC yesterday. Water temperatures at the buoy were 17°C (63°F), far below the 26°C threshold usually needed to sustain a tropical storm. The coldest waters I've seen a tropical storm form in were 22°C during Hurricane Epsilon of 2005. I doubt that NHC would name this system if they did have responsibility for the Mediterranean, due to the cold water temperatures.

"Rolf" is expected to move slowly northwards into the coast of South France by Wednesday night. Meteo France is predicting heavy rains of 30 - 40 mm/hr (1.2 - 1.6"/hr) will affect the coast Tuesday night through Wednesday, with sustained winds of 50 mph, gusting to 75 mph.


Figure 3. Hybrid subtropical storm of October 8, 1996, off the coast of Italy. According to Reale and Atlas (2001), the storm had characteristics similar to a hurricane, but formed over water of 21.5°C. "The maximum damage due to wind occurred over the Aeolian Islands, at 38.5°N, 15°E, to the northeast of Sicily: assistance for disaster relief was required. Unfortunately, no weather station data were available, but the media reported sheds, roofs and harbor devices destroyed, and houses and electric lines damaged, due to "extremely strong westerly wind." The perfect agreement between the observations at Ustica, the storm scale, the eye-like feature position and the damages over the Aeolian Island reasonably suggest that the hurricane-level intensity of 32 m/s (72 mph) was reached over the Aeolian Islands." A similar hybrid low affected Algeria on 9 - 10 November 2001. This storm produced upwards of 270 mm (10.6") of rain, winds of 33 m/s (74 mph), and killed 737 people near Algeirs, mostly from flooding and mud slides. Image credit: Dundee satellite receiving station.

According to research published by Gaertner et al. (2007), an increase in ocean temperatures of 3°C in the Mediterranean by the end of the century could lead to hurricanes forming there. Miguel Angel Gaertner of the University of Castilla-La Mancha in Toledo, Spain, ran 9 different climate models with resolutions of about 50 km and found that some (but not all) of the models simulated hurricanes in the Mediterranean in September by the end of the century, when ocean temperature could reach 30°C.

Though the Mediterranean may start seeing hurricanes by the end of the century, these storms should be rare and relatively short-lived for three reasons:

1) The Mediterranean is quite far north and is subject to strong wind shear from jet stream activity.

2) The waters are shallow, and have relatively low heat content. There is no deep warm water current like the Gulf Stream.

3) The Mediterranean has a lot of large islands and peninsulas poking into it, increasing the chances that a tropical storm would weaken when it encountered land.

References
Meteo France has an interesting animation of the predicted winds and temperatures over the next few days.

Gaertner, M. A., D. Jacob, V. Gil, M. Dominguez, E. Padorno, E. Sanchez, and M. Castro (2007), Tropical cyclones over the Mediterranean Sea in climate change simulations,, Geophys. Res. Lett., 34, L14711, doi:10.1029/2007GL029977.

Reale, O., and R. Atlas. 2001: Tropical Cyclone-Like Vortices in the Extratropics: Observational Evidence and Synoptic Analysis, Weather and Forecasting, 16, No. 1, pp. 7-34.


Figure 4. Radar reflectivity image from the Tipton, OK tornado of November 7, 2011, showing a classic hook echo.


Video 1. Reed Timmer video of the November 7, 2011 tornado in Tipton, OK. Here's another excellent video of the Tipton tornado and a tornado near Manitou, OK from Texas Storm Chasers. Storm chasing IS dangerous: one storm chaser had his vehicle overturned, but got into another vehicle and continued the chase.

Shaken and stirred: an earthquake and tornado for Oklahoma
It was a rare multi-natural hazard day for Oklahoma yesterday, as the state experienced both a tornado and an earthquake, six hours apart. The damaging magnitude 5.6 earthquake that shook the state Saturday night spawned a magnitude 4.7 aftershock at 8:46 pm CST yesterday, 44 miles east of Oklahoma City. And at 2:47 pm CST, a tornado touched down in Southwest Oklahoma near Tipton. The tornado destroyed an Oklahoma State University agricultural office, and damaged a hay barn at a dairy farm. No injuries were reported. The UK MailOnline has an interesting article showing the radar image from Saturday's quake, which captured a massive groups of birds and insects that took flight after the ground shook.

This afternoon, NOAA's Storm Prediction Center has placed Southeast Oklahoma, East Texas, Southeast Missouri, and most of Arkansas in its "Slight Risk" area for severe weather, thanks to a strong low pressure system moving across the Plains. During the late afternoon, severe thunderstorms with high winds and large hail and expected over the region, and we cannot rule out an isolated tornado.

Bering Sea superstorm targets Alaska
A massive blizzard the National Weather Service is calling one of the most severe Bering Sea storms on record is gathering strength today to the west of Alaska. The storm is expected to "bomb" to a central pressure of 945 - 950 mb Tuesday night, and to 940 mb on Wednesday. These pressures, characteristic of a Category 3 hurricane, will be strong enough to generate sustained winds of Category 1 hurricane force over the waters to the west of Alaska, with winds of 50 - 70 mph expected along portions of the coast. Nome, Alaska is expecting a storm surge of 8 - 10 feet. Waves of 15 - 25 feet with ice on top will batter the shores, causing severe damage to the coast.

Jeff Masters

Chaser Cap (OIG)
This is a screen capture taken during a chase near Lawton, OK.
Chaser Cap

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This is going to be a fall season to remember,just about everything except the kitchen sink,better keep your eyes to the sky.
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Agree with the posters.

I still feel the statement borders on hype and it's something that we understand here, but when regurgitated ad naseum on the W-channel and the evening news, it also somehow finds it's way into my insurance bill.

"We understand customers are upset about the latest premium increase, but 2011 was the 6th busiest season since records were kept in the last 160 years"

Thanks
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Quoting Mach80:
I am a little suspect of the statement "6th busiest Atlantic hurricane season since record keeping began in 1851."

There had to be many seasons with unknown storms that lived and died in the open water that were unknown to weather observers.

Without the benefit of satellite observations, it's almost like saying "This year is the 6th busiest for racoon sightings in my town since 1851" when in fact it's only been since the 1960's that observers were out looking at night with flashlights.


And so you should be.

It's based off what we know, but we can be reasonably sure that most, if not all, seasons had higher numbers than documented. We just don't know how many, particularly in relation to today. The further you go back, the more you miss.

Still doesn't take away the fact that this season is special. Even with estimated numbers, as opposed to the official statistics, 18 storm seasons do not occur often. Guess it's been discussed a fair bit lately on here.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
So Sean is now fully tropical and looking nice, although its convection is a little on the light side.

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Quoting Mach80:
I am a little suspect of the statement "6th busiest Atlantic hurricane season since record keeping began in 1851."

There had to be many seasons with unknown storms that lived and died in the open water that were unknown to weather observers.

Without the benefit of satellite observations, it's almost like saying "This year is the 6th busiest for racoon sightings in my town since 1851" when in fact it's only been since the 1960's that observers were out looking at night with flashlights.
That issue comes up quite regularly..I think they are doing there best with what they have in that department..
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I am a little suspect of the statement "6th busiest Atlantic hurricane season since record keeping began in 1851."

There had to be many seasons with unknown storms that lived and died in the open water that were unknown to weather observers.

Without the benefit of satellite observations, it's almost like saying "This year is the 6th busiest for racoon sightings in my town since 1851" when in fact it's only been since the 1960's that observers were out looking at night with flashlights.
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Quoting Grothar:
Will all of you bloggers stop posting X's. I want to see some action.


Good to see ya Gro
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Quoting VAstorms:


That is an impressive looking storm. So what impact might that have for the lower 48. I assume a storm like that will funnel extremely cold air into the lower 48 as it passes.
a Pacific front possibly. I'm still looking at it. Hello VA.
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Alaska
Member Since: August 2, 2010 Posts: 21 Comments: 9882
Member Since: August 2, 2010 Posts: 21 Comments: 9882
Quoting hydrus:
How bout a link..Maybe....Mornin Gro...Link


That is an impressive looking storm. So what impact might that have for the lower 48. I assume a storm like that will funnel extremely cold air into the lower 48 as it passes.
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Quoting hydrus:
My vote is yes...Good afternoon cott..


Evening. It's possible in one of the brief climatic upswings during the epoch.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting Cotillion:
And the Atlantic keeps disliking ending a season at 17 storms.

Hurricanes in the Med would be something, though won't be around to see it. 3c increase in around 100 years is quite sharp and sounds a bit too aggressive, though the Med is particularly situated.

I wonder if hurricanes have ever formed in the Mediterranean (at least in the Holocene). Be too far back for paleotempestology in likelihood.

My vote is yes...Good afternoon cott..
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Quoting hydrus:
How bout a link..Maybe....Mornin Gro...Link


Hi, hy! That's better.
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And the Atlantic keeps disliking ending a season at 17 storms.

Hurricanes in the Med would be something, though won't be around to see it. 3c increase in around 100 years is quite sharp and sounds a bit too aggressive, though the Med is particularly situated.

I wonder if hurricanes have ever formed in the Mediterranean (at least in the Holocene). Be too far back for paleotempestology in likelihood.

Member Since: August 23, 2008 Posts: 7 Comments: 5300
Guess Dr. M didn't see that this is actually a tropical cyclone and not "like a tropical cyclone"

TXMM21 KNES 071819
TCSMED

A. 01M (NONAME)

B. 07/1800Z

C. 41.1N

D. 5.3E

E. THREE/MET-9

F. T2.5/2.5/D1.5/24HRS

G. IR/EIR/SWIR

H. REMARKS…DT=2.5 BASED ON .5 BANDING ON LOG10 SPIRAL. PT=2.5. MET=2.0. FT IS BASED ON DT. DEEP CONVECTION HAS PERSISTED LONG ENOUGH AROUND THE LOW LEVEL CENTER FOR A TROPICAL CLASSIFICATION.

I. ADDL POSITIONS

NIL

…SCHWARTZ

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Quoting Grothar:
Will all of you bloggers stop posting X's. I want to see some action.
How bout a link..Maybe....Mornin Gro...Link
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Member Since: Posts: Comments:
Will all of you bloggers stop posting X's. I want to see some action.
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Quoting WarEagle8:

Looks like Sean has more storms wrapping around the center. Look at the hook!


EF-5 Waterspout!
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Looks like Sean has more storms wrapping around the center. Look at the hook!
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So what is more fun than an earthquake?

An earthquake while sitting in the dark during a raging thunderstorm.

An interesting observation in the OKC paper this morning:

"For the record, we believe Oklahomans have little to fear from tsunamis or alpine avalanches."

Not so sure lately. Everything is fine - though quite interesting past few days.

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Sean and that upper-level low are responsible for some very strange conditions in Bermuda. Well, according to people I know from there, they've been having huge storms and incredibly large swells for days now, and the forecast suggests that this will continue for days more. They've had most of the coastal areas breached already, I wonder how they'll fare when Sean makes his closest pass. He seems to be organizing quickly. Do you think there's a chance he can be stronger than forecast?

And that Alaskan weatherbomb system looks like it'll be ferocious. And the cyclone in the Mediterranean? Tornadoes, earthquakes? I'm not religious, but this seems very Ten Commandments-y to me, haha.
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Quoting GeorgiaWx65:

We have seen this occur for a while back in the mid 1980's where anti-cyclonic highs and also deep lows treked up near and north of the 60 degree line to the pole. It also occurred in the 1940's, so not unprecedented and not a permanent trend by any means.

Still interesting nonetheless!
did not mean to infer any trends or precedence... just that everything seems to 'churn up' at the same time, and my inference being seasonal shifts.. my intrigue being the active bombing out of the Aleutian low ;)
Member Since: July 31, 2008 Posts: 0 Comments: 1320
Dr. Masters,

Can't remember where I found it off the top of my head, but while trying to put this Mediterranean storm in context I did some reading and some link chasing on various blogs. From that I recall some sources suggesting that warm-core, semi-tropical systems in the Mediterranean happen maybe as often as every 1-2 years, and even the strongest of them occur over much cooler sea surface temperatures than one would expect. I do not recall a mechanism suggested for why this would happen, but I'm wondering if our current "threshold" for water temps based on Atlantic experience may be a little fuzzy in the Mediterranean due to factors we do not fully understand?
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Quoting presslord:
I have friends in Cold Bay AK...wunder how they'll fare in the coming storm...
I can see some of it here..Good morning..This NASDA link how strong it is..Link Then again maybe not..
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a weird week indeed, not too mention a comet, astroid, and now the emergency whatever thing for tomorrow...and alos the tsunami warning stuff?? something is going on...oh and almost forgot about the sunspots that are gong to be facing us...should be a intersting rest of the week....
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Weather at a Glance
Weather Station
Cold Bay (PACD)
Elevation
95 ft


Temperature
21 F
Feels Like 13 F
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Thanks Jeff...
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I have friends in Cold Bay AK...wunder how they'll fare in the coming storm...
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Dang... active week!
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AL-19 "Sean" WV Image/Loop

..click image for Loop

Sean (AL19)
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Thanks Dr. Masters. A big swirly in the Mediterranean, earthquakes AND tornadoes in Oklahoma. What a weird week!
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I told you all we'd get one more storm.
Thanks Dr.
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this Alaskan storm has my interest! crazy part of me thinks there is a teleconnection of intensifying cyclonic activity in the northern hemisphere about... season shifts are exciting times for us weather folks :)
Member Since: July 31, 2008 Posts: 0 Comments: 1320
Thanks for the update. Lots going on for the second week of November...
Member Since: November 8, 2009 Posts: 4 Comments: 13744
hello dr jeffmasters how cold does the gfs show for jacksonville
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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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