Otto transitioning to a tropical storm

By: Dr. Jeff Masters , 1:35 PM GMT on October 07, 2010

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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

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Quoting Bordonaro:

Orca is getting all your rain and mine too!!
Come to Puerto Rico and you get all the rain you need!
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Quoting StSimonsIslandGAGuy:
It's true Neapolitan

Rainfall Oct 1 to Oct 7, 2005: 23.18"
Rainfall Jan 1 to Oct 7, 2010: 22.49"


I may have used the wrong word; I didn't mean "incredible" as in non-credible; I meant it as a synonym for "amazing"... :-)
Member Since: November 8, 2009 Posts: 4 Comments: 13538
Quoting sunlinepr:
Soon there will be an eye....


Not where you think it will be.

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Soon there will be an eye....
Member Since: August 2, 2010 Posts: 21 Comments: 9814
Man, this trough on the GFS@138


With high shear present, this could be the Peninsula's first active front.

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As of 11PM, Otto's ACE stands at .75, meaning he's already been a more energetic storm than Bonnie, Gaston, or--of course--Nicole. His ACE should pass that of Hermine and Matthew tomorrow, and he's got a shot at passing Colin as well if he can hang around until Saturday morning. Not that he's a powerhouse, mind you; he's still accumulated just 1/56th the energy Igor did.

Anyway, with that tidbit out of the way, here's the current season visual:

Member Since: November 8, 2009 Posts: 4 Comments: 13538
My 10PM CDT Blog Update On TS Otto, take a look folks, thanks: Link
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Well, I've been to webpages where a small windows tells me, where I'm located.... It's a service you pay to identify people accesing your site....
Quoting pvbeachbum:
Interesting list - I have been on this blog since 2005, but didn't appear on the list with my town and state...wonder how they get the info?

Member Since: August 2, 2010 Posts: 21 Comments: 9814
Will check back on Otto in the am - time for bed now. Good night all!
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Quoting cat5hurricane:
I think when you modify you blog profile & plug in your city when it prompts you to, then it works.


I think you are right Cat5 - I just added my location to my personal blog - maybe that will make me show up...
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Quoting beell:


But does it get buried in Central America or does it sneak out to the NE before the rebuilding ridge slams shut? Or maybe it splits?


Too, early to say. However, looking at things ATM it may be there a while and the pattern of strong troughs looks to continue.
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000
WTNT42 KNHC 080241
TCDAT2
TROPICAL STORM OTTO DISCUSSION NUMBER 8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL172010
1100 PM AST THU OCT 07 2010

A LITTLE BIT OF WESTERLY SHEAR IS AFFECTING OTTO...AND THE LOW-LEVEL
CENTER IS EMBEDDED BENEATH THE WESTERN SIDE OF A NEARLY CIRCULAR
AREA OF DEEP CONVECTION. SATELLITE INTENSITY ESTIMATES ARE T3.5/55
KT AND T3.0/45 KT FROM TAFB AND SAB...RESPECTIVELY...AND THE
INITIAL INTENSITY WILL BE MAINTAINED AT 50 KT. STRENGTHENING IS
STILL POSSIBLE DURING THE NEXT 48 HOURS SINCE THE VERTICAL SHEAR IS
EXPECTED TO BE RELATIVELY LIGHT. THE ONE BIG CHANGE IN THE
INTENSITY GUIDANCE IS THAT MOST OF THE MODELS NOW SHOW A PEAK IN
INTENSITY OCCURRING AROUND 48 HOURS...WHICH IS ABOUT 12 HOURS LATER
THAN INDICATED IN THE PREVIOUS ADVISORY. THE NEW FORECAST...
THEREFORE...DOES NOT SHOW WEAKENING COMMENCING UNTIL AFTER 48
HOURS. THIS SOLUTION IS CLOSE TO THE STATISTICAL AND GLOBAL
GUIDANCE BUT TENDS TO DISREGARD THE HWRF AND GFDL SINCE THOSE
MODELS APPEAR TO DISSIPATE OTTO TOO SOON.

THE INITIAL MOTION IS 070/8. THE CYCLONE IS BEING PICKED UP BY A
LARGE MID/UPPER-LEVEL TROUGH OVER THE WESTERN ATLANTIC AND IS
EXPECTED TO BECOME EMBEDDED WITHIN FAST MID-LATITUDE WESTERLIES
OVER THE NEXT 24-48 HOURS. BY THE END OF THE FORECAST...MODEL
GUIDANCE SUGGESTS THAT THE FLOW WILL SPLIT WITH THE POST-TROPICAL
CYCLONE TAKING THE SOUTHERN ROUTE AND SLOWING DOWN AS IT NEARS THE
AZORES. THE OFFICIAL FORECAST IS NOT MUCH DIFFERENT FROM THE
PREVIOUS ONE AND GENERALLY LIES BETWEEN THE FASTER ECMWF AND SLOWER
GFS.

THE FSU PHASE SPACE DIAGRAMS SHOW THAT OTTO SHOULD BEGIN
EXTRATROPICAL TRANSITION IN THE NEXT 24-36 HOURS...BUT THEY ALSO
SUGGEST THAT IT WILL NOT BECOME A DEEP COLD-CORE SYSTEM WITHIN THE
5-DAY FORECAST PERIOD. AS SUCH...CONFIDENCE IS NOT HIGH THAT OTTO
WILL BECOME COMPLETELY EXTRATROPICAL BY 72 HOURS.

FORECAST POSITIONS AND MAX WINDS

INITIAL 08/0300Z 24.1N 66.6W 50 KT
12HR VT 08/1200Z 24.9N 65.1W 55 KT
24HR VT 09/0000Z 26.7N 62.0W 55 KT
36HR VT 09/1200Z 29.0N 57.6W 60 KT
48HR VT 10/0000Z 31.4N 52.1W 60 KT
72HR VT 11/0000Z 36.5N 38.5W 50 KT...POST-TROP/EXTRATROP
96HR VT 12/0000Z 39.0N 27.0W 45 KT...POST-TROP/EXTRATROP
120HR VT 13/0000Z 36.5N 23.0W 35 KT...POST-TROP/EXTRATROP

$$
FORECASTER BERG
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Quoting xcool:
buzz

Hello, how are you tonight :O)??

ZCZC MIATCPAT2 ALL
TTAA00 KNHC DDHHMM
BULLETIN
TROPICAL STORM OTTO ADVISORY NUMBER 8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL172010
1100 PM AST THU OCT 07 2010

...OTTO ACCELERATING EAST-NORTHEASTWARD TOWARD THE OPEN ATLANTIC...


SUMMARY OF 1100 PM AST...0300 UTC...INFORMATION
-----------------------------------------------
LOCATION...24.1N 66.6W
ABOUT 575 MI...930 KM S OF BERMUDA
MAXIMUM SUSTAINED WINDS...60 MPH...95 KM/HR
PRESENT MOVEMENT...ENE OR 70 DEGREES AT 9 MPH...15 KM/HR
MINIMUM CENTRAL PRESSURE...992 MB...29.29 INCHES


WATCHES AND WARNINGS
--------------------
THERE ARE NO COASTAL WATCHES OR WARNINGS IN EFFECT.


DISCUSSION AND 48-HOUR OUTLOOK
------------------------------
AT 1100 PM AST...0300 UTC...THE CENTER OF TROPICAL STORM OTTO WAS
LOCATED NEAR LATITUDE 24.1 NORTH...LONGITUDE 66.6 WEST. OTTO IS
MOVING TOWARD THE EAST-NORTHEAST NEAR 9 MPH...15 KM/HR. AN INCREASE
IN FORWARD SPEED IS EXPECTED DURING THE NEXT COUPLE OF DAYS. ON
THE FORECAST TRACK...OTTO SHOULD PASS WELL TO THE SOUTH AND
SOUTHEAST OF BERMUDA FRIDAY AFTERNOON AND FRIDAY EVENING.

MAXIMUM SUSTAINED WINDS ARE NEAR 60 MPH...95 KM/HR...WITH HIGHER
GUSTS. SOME STRENGTHENING IS FORECAST...AND THERE IS STILL SOME
POSSIBILITY THAT OTTO COULD BECOME A HURRICANE DURING THE NEXT DAY
OR TWO.


TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 90 MILES...150 KM
FROM THE CENTER.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 992 MB...29.29 INCHES.


HAZARDS AFFECTING LAND
----------------------
RAINFALL...ADDITIONAL HEAVY RAINFALL IS POSSIBLE IN THE NORTHERN
LEEWARD ISLANDS...THE VIRGIN ISLANDS...AND PUERTO RICO DURING THE
NEXT DAY OR SO.
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Quoting StSimonsIslandGAGuy:
More rain fell during that week than has fallen here since Jan 1st this year.


Given that we just finished the rainy season, that's a pretty incredible statement...
Member Since: November 8, 2009 Posts: 4 Comments: 13538
Member Since: August 2, 2010 Posts: 21 Comments: 9814
Quoting pvbeachbum:
Interesting list - I have been on this blog since 2005, but didn't appear on the list with my town and state...wonder how they get the info?



Seems like they check out the IP address.... that way they know where you are
Member Since: August 2, 2010 Posts: 21 Comments: 9814
Not on list either
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Quoting pvbeachbum:
Interesting list - I have been on this blog since 2005, but didn't appear on the list with my town and state...wonder how they get the info?

Member Since: Posts: Comments:
Interesting list - I have been on this blog since 2005, but didn't appear on the list with my town and state...wonder how they get the info?

Quoting sunlinepr:
For those of you who never explored this blog, and want to know if other members live near by visit this link....

Link
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I hope Orca is enjoying all his rain. He has a 9.7" bulls-eye over his house. Dallas-Ft Worth, TX might get 1/3" or rain over the weekend O).
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Quoting cat5hurricane:
Exactly.

It's go time now.

I know there is no model support for RI, but the way this season has gone it would not surprise me if Otto became a Hurricane and maxed out at 80-100 MPH.
Member Since: August 25, 2009 Posts: 20 Comments: 6785
482. xcool
buzz
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Quoting cat5hurricane:
Yeah what a difference a day makes...even 18 hours. He was anemic early this morning when I woke up.

Amazing what an ULL and wind shear can do! As soon as the ULL dissipated and shear relax, Otto took off to the races!
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Here in Naples, we've received 42.5" since Jan 1, and 30.69" since June 1, meaning we're down "just" 3.5" for the year...which is far better than the 17.5" we were behind on this date last year.

(FWIW, the record rainfall Naples received for this date was in 2005 when the remnant low of TS Tammy--yes, the 'T' storm--gave us 2.5", while giving Darien, GA, 14.48"!)
Member Since: November 8, 2009 Posts: 4 Comments: 13538
Quoting HurricaneDean07:
Yep, now that I think of it he really did last night!

First Otto was an over sized comma, then he turned into a life preserver, now he look like a big blob. God does have a sense of humor :O)
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Quoting Bordonaro:

:O)


I have not been this psyched to go to a football game ever. Miami-FSU under the lights. Beware folks, a Cateogry 5 is going to roll into Miami Saturday night ;)
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Quoting StSimonsIslandGAGuy:
We've had no rain for 10 days. Not one drop.

Orca is getting all your rain and mine too!!
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Quoting cat5hurricane:

LOL. Ike was comparing him to a huge horseshoe this morning & posted an Indianapolis Colts horseshoe.

TS Danny last year looked better than Otto did yesterday. Now he looks like a compact blog of convection!
Member Since: August 25, 2009 Posts: 20 Comments: 6785
No eye.

Just an overshooting top

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Quoting caneswatch:


I know a hurricane that will not get attacked by shear on Saturday night ;)

:O)
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Hmmmm...not an eye because a recent microwave overpass from this evening reveled that the system has yet to develop an eyewall, but the feature is interesting nonetheless.



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468. beell
Quoting CyclonicVoyage:


Evening All.

Loving it in Jupiter, in the high 60's tomorrow morning. In other news, look for 98L in the SW Caribb tomorrow, she's stationary and looking suspicious.


But does it get buried in Central America or does it sneak out to the NE before the rebuilding ridge slams shut? Or maybe it splits?
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Quoting StSimonsIslandGAGuy:


I read it to mean what the wind velocity would be at the next advisory (11 PM EDT). But 60 kts is not going to happen.

However, I do think Otto will be a Cat 1 hurricane tomorrow night for a little while.


Probably will. Shear will stay under 10 knots for a bit (thanks Miami for showing that) before it gets up into 30+ knots of shear.
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Quoting Bordonaro:

The HH will not fly into Otto, I bet you if they did they would find 60-70MPH winds. I believe Otto will become a CAT 1 with 80 MPH winds by Friday evening. Then get attacked by shear on Saturday night and take off to the NE.


I know a hurricane that will not get attacked by shear on Saturday night ;)
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Quoting Bordonaro:

Much better than last night, when he looked like a big life preserver ring!
Yep, now that I think of it he really did last night!
Member Since: October 3, 2010 Posts: 40 Comments: 4129
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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.