Otto transitioning to a tropical storm
Subtropical Storm Otto, the 15th named storm of this very busy 2010 Atlantic hurricane season, is here. Otto is not a threat to bring high winds to any land areas, but will produce heavy rains over Puerto Rico, the Virgin Islands, and northern Lesser Antilles. Radar estimated rainfall over Puerto Rico and the Virgin Islands (Figure 2) shows rainfall amounts in excess of eight inches have fallen in several locations over the past three days, and the St. Thomas Airport officially recorded 9.30" of rain so far from Otto. Not surprisingly, Flash Flood Warnings are posted for both the Virgin Islands and Puerto Rico. Weather radar out of Puerto Rico shows that a large area of heavy rain will continue to affect the Virgin Islands and eastern Puerto Rico today. Martinique radar shows considerably less activity over the Lesser Antilles.
Figure 1. NASA MODIS image of Subtropical Storm Otto taken at 12:55pm EDT October 6, 2010.
Satellite loops show Otto's heaviest thunderstorms lie in two bands to the south, many hundreds of miles from the storm's center. This is characteristic of a subtropical storm, which is a hybrid between a tropical storm and an extratropical storm. An upper level low pressure system over Otto has pumped cold, dry air aloft into the storm, keeping it from being fully tropical. However, the upper low is weakening, and Otto has recently developed a burst of heavy thunderstorms near its center, and very tropical storm-like spiral bands are now developing to the east and south of Otto's center. Otto is fast becoming fully tropical, and will be called Tropical Storm Otto later today. The storm's newly developing spiral bands will mostly stay offshore, but a few heavy rain showers capable of dumping 1 - 2 inches of rain may affect the Turks and Caicos Islands today, as well as the northern Dominican Republic. The heavier rains in Otto's old rain band over Puerto Rico and the Virgin Islands will continue to dump flooding rains in those locations through tonight. Steering currents favor Otto being lifted northwards and then northeastwards out to sea by Friday. Given the very warm waters of 28 - 29°C and low wind shear of 5 - 10 knots today, Otto may approach hurricane strength before high wind shear in excess of 20 knots impacts the storm Friday night.
Figure 1. Radar-estimated rainfall from Tropical Storm Otto over Puerto Rico and the Virgin Islands shows that rains in excess of eight inches (white colors) have fallen in many regions. The strange ray-like pattern to the east of the radar location (the white "+" symbol) is due to mountains blocking the radar beam.
Elsewhere in the tropics
An area of disturbed weather has formed in the Western Caribbean, a few hundred miles west of Jamaica. The disturbance has a moderate area of intense thunderstorms that brought close to two inches of rain to Grand Cayman Island over the past day. The disturbance is under a high 15 - 25 knots of wind shear, and is not likely to develop significantly today. The disturbance is headed south at 10 - 15 mph, and will bring heavy rains to northeastern Honduras and Nicaragua over the next two days. None of the models develop the disturbance, but it does have some potential for slow development beginning on Friday when it will be off the coast of Nicaragua, in a region of lower wind shear and higher moisture. NHC is giving the disturbance a 10% chance of developing into a tropical depression by Saturday.
Monsoon flooding kills 139 in Asia
Heavy monsoon rains triggered flash flooding in a remote section of Indonesia this week that killed at least 91 people and left 100 more missing. In Vietnam, heavy rains of up to 51" (1300 mm) have fallen since Friday, resulting in river flooding that killed at least 48 people, with 23 people still missing. Over 34,000 people are homeless from the floods, which hit five provinces from Nghe An to Thua Thien-Hue, a swath of territory starting some 300 km (180 miles) south of Hanoi and stretching south. Heavy monsoon rains of up to seven inches over the past week have also hit nearby Hainen Island in China. The resulting flooding was the worst in 50 years there, and killed one person and forced the evacuation of 55 villages with 213,000 people.
Press
I've been a subscriber for several years to NewScientist magazine, a weekly science news magazine that does a great job staying abreast of all the latest breaking science happenings. This week's October 4 issue features a 4-page section on Extreme Weather that I wrote for them as part of their "Instant Expert" series. If you haven't ever seen the magazine, I enthusiastically recommend taking a look.
If you're a fan of the geek humor xkcd webcomic, see if you can find me on the hilarious map of the "blogosphere" on comic artist Randall Munroe's latest xkcd comic. I like the disparity between my influence in September vs. March, but thought I should have been closer to the "Bay of Flame!" I also appeared in a mouse "rollover" text box in an xkcd comic during the Gulf oil disaster earlier this year.
Jeff Masters
Reader Comments
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hee hee
I don't remember a time in 17 years in SWFL that we went this cloudless for this many days in a row. It REALLY is like november down here. The door is closing fast, I hope other bloggers remember this year and try to show tolerance for other peoples viewpoints. Nobody has 100% accurate forecast and even in the face of DOOM.....it was an average season for the conus.
Still raining cats and dogs (or should that be mongoose and iguanas?) here on St. Croix. About 12" in past 72 hours here on the rainy side of the island. I wish that Otto would pick up some steam and move on out of here!
Rich
Had to hunt a pic to make it weather related.
That's great news.
I'm going to assume for a moment that you're serious, and respond to you. A few facts:
--Over the past 15 seasons--that is, from 1995 to 2009, or what is known as the current active tropical era--the average number of named storms altogether is 14.3. We're at 15. That's above average.
--Over that same 15-year period, the following average number of named storms have happened each month:
June: 0.6
July: 1.5
August: 3.6
September: 4.4
October: 2.4
November: 0.6
The numbers for 2010 are:
June: 1
July: 1
August: 4
September: 8
October: 1 (and counting)
November: ?
As you can see, 2010 beat the 15-year average in all but one of those months July). Overall, then: that's above average.
--During that same period, ACE has averaged 138 and change. 2010 stands at 131 and change now, and there's little reason to doubt we can't add more (or even much more). That's above average.
--During that same period the average number of hurricanes has been 7.7. With Otto expected to become a hurricane today or tomorrow, that'll give us 8. That's above average.
--During that same period, the average number of intense storms has been 3.7. We're at five. That's above average.
--However...even if we go by your ten-year period, this year's current ACE of 131 is already above the ten-year average of 128. That's above average.
--The ten-year average is 14.9 total named storms. We're at 15. That's above average.
--The ten-year average for hurricanes is 7.4. We'll have eight as of tomorrow. That's above average.
--The ten-year average if intense storms is 3.6. We have five. That's above average.
--Not to mention, of course, both the fifteen-year and ten-year averages include the highly anomalous 2005. Take that out of the picture, and we're considerably further above average in all the categories listed above.
Bottom line: any way you slice it, this season has been above average...and there are still nearly two full months of the hurricane season to go. The only way we're below average, I suppose, is in terms of death and destruction in the United States, and for that, we can all be thankful.
Howdy, folks! So, odds on Paula formation in the next 7-10 days?
The 2010 Atlantic hurricane season has been very active in the number of storms but is likely to go down as a non-event for most people in the United States, which has so far dodged a major landfall, the top official U.S. hurricane forecaster said this week.
Before the June 1-Nov. 30 season got under way, residents of hurricane danger zones were warned by many forecasters they faced a very high probability of a major hurricane making landfall along the U.S. coastline.
That has not happened and with the most active part of the season winding down in the next two weeks or so, the chances of a major impact on the U.S. mainland or on energy interests in the Gulf of Mexico are ebbing.
"If you just use (U.S.) landfall as a criteria and did not pay attention to the numbers, you'd think this was a really quiet year,'' U.S. National Hurricane Center director Bill Read told Reuters.
"A couple of relatively minor impacts and some flooding and that's what we'd have to show for it,'' he said.
Read said 2010 was still likely to go down in the record books as another in a string of exceptionally busy seasons, however. The United States had just been very lucky in not getting hit by a major hurricane.
Hurricane Earl, which became a Category 4 hurricane on the five-step Saffir-Simpson scale of storm intensity, came the closest by approaching to about 100 miles off North Carolina and southern New England last month, Read said.
"That's a relatively narrow escape if you look at it from the global perspective,'' he said.
Read also noted that the 2010 Atlantic season had taken a high toll in flood and mudslide deaths in Central America and Mexico, meanwhile.
An average season produces about 10 storms, of which six become hurricanes. This year has seen 15 named storms so far, with Otto forming as a subtropical storm over the Western Atlantic Wednesday, but posing no immediate threat to land.
U.S. oil and gas installations in the Gulf of Mexico have been virtually unscathed by this year's hurricane season, which posed an early threat to efforts to control and clean up oil spewing from the ruptured Gulf of Mexico well owned by BP Plc, which was the worst oil spill in U.S. history.
Read said the eastern portion of the Gulf and the Caribbean, along with southern Florida, were not totally out of the woods yet, however.
With sea surface temperatures still very high, conditions for storm or hurricane formation, especially over the Caribbean, remain favorable, Read said.
Tropical cyclones draw energy from warm sea water.
Read expressed particular concern for impoverished and nearly treeless Haiti, saying it had just been "an amazing stroke of good fortune'' that the earthquake-ravaged nation had not been hit by a major storm so far this year.
"They're so vulnerable, it wouldn't take much to cause a crisis,'' he said.
LANDFALLS TOUGH TO PREDICT
Though forecasters have cut their errors in predicting the track of a hurricane, Read said there were still problems in terms of their long-term "skill'' in pointing to landfalls.
In June, for instance, leading U.S. forecasters at Colorado State University had said the chance a major hurricane would make a landfall on the U.S. coastline this year was 76 percent compared with the last-century average of 52 percent.
But Read said it was not surprising no major hurricanes had hit the U.S. coast directly, given global oceanic and atmospheric conditions.
"It's highly dependent on where they form and the steering currents at the time,'' Read said, when asked about the ability to predict landfalls.
"With the weather pattern that was in place and the fact that these (storms) formed so far out to the east, it's not surprising that they turned off to the north,'' he said.
"As soon as you find a weakness in the big high, the Bermuda-Azores high, you'll get that effect. That's why Igor and Danielle and Julia among others went straight north pretty much.''
The weather pattern known as La Nina was also a factor behind this year's hurricane season, since it brought wind conditions that foster Atlantic hurricanes.
La Nina is a cooling of the sea surface in the tropical Pacific and has had an impact on global weather. It tends to reduce the shearing winds that can disrupt nascent storms in the Atlantic.
"In the eastern Pacific this will be one of the quietest seasons on record,'' Read said. "That's what you see in a La Nina pattern, a lessening of storms in the Pacific and a greater chance of storms in the Atlantic.''
Neopolitan is one of my most favorites here. Love reading his posts
Thanks
I don't remember ever being this cool in the 1st week of October in SWFL for the 35 years i've lived here. I think we're in Global Cooling. Hope this winter isn't like the last one we had. BBBBRRRR!!!!
I'll buy in at 8-to-2...
Love the pic, beautiful to look at
'exceptionally busy?' That's stretching it a bit. above average sure. exceptionally busy? eh.
wouldn't that be 4-to-1?
Relative to climo, chances are quite a bit above normal:
Climo:
Current:
note to self.. if Neapolitan offers a bet... take it lol
+5 lol
GFDL 850vort
GFDL cross section of Otto.
And overall
exactly, until you can have a .7 storm occur, there is no "exactly" average year, but -1-2 storms is not SIGNIFICANTLY above or below average.
meaning, if 15.7 is average, I wouldn't consider 15 below average...
Yes. Or 16-to-4. Or 256-to-64. Or 2048-to-512. Or... :-)
I guess he hasn't spent a lot of time on this blog in 2010...with the inevitable "pattern change" hammered down our throats...that never happened.
Even Read admits forecasting tracks long-term is not a safe bet.
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