Dr. Jeff Masters' WunderBlog

Otto transitioning to a tropical storm

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

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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601. Cotillion 12:04 PM GMT on October 08, 2010
Quoting pottery: Real Nice right now, Cot! Seeing a little dry-spell that always occurs around this time and called 'Petit Careme' by the old French Planters. Thought we would get some weather from the area east of here, but it looks to be going north. Enjoying the dry-out, after some months of heavy stuff.. Yes, that's probably useful, heard a few weeks ago when you got drenched. Here it is surprisingly pleasant as well, particularly for October. Clear skies, a bit of a stiff breeze, but 18C-19C (high 60s). That's above normal for this time of year, certainly. Looks to be a lovely weekend. Member Since: August 23, 2008 Posts: 7 Comments: 5300

602. aislinnpaps 12:05 PM GMT on October 08, 2010
Quoting stillwaiting: fire wx warning starting at noon for my area((sarasota)..dam its dryyyyyyyyy!!!,ready for a cat 1or strobg ts w/ lotsa rain!!! The whole state of Louisiana has been under one for several days now. We're the second driest state in the country right now. Member Since: August 22, 2009 Posts: 0 Comments: 2540

603. PensacolaDoug 12:08 PM GMT on October 08, 2010
It's not unusual to have couple of fronts push thru to the GOM this time of year. What does seem unusual (to me at least) is to have them quite this strong going so far south while being re-inforced so frequently. Give us this pattern in January and it's gonna be cold in Florida! Member Since: July 25, 2006 Posts: 0 Comments: 4831

604. GeoffreyWPB 12:09 PM GMT on October 08, 2010
Member Since: September 10, 2007 Posts: 0 Comments: 9247

605. BobinTampa 12:09 PM GMT on October 08, 2010
Quoting PensacolaDoug: It's not unusual to have couple of fronts push thru to the GOM this time of year. What does seem unusual (to me at least)is to have them quite this strong going so far south while being re-inforced so frequently. Give us this pattern in January and it's gonna be cold in Florida! I usually love the cold weather. but last year, even I was saying 'enough!!!' I think we had well over a week of highs in the 50's if I'm not mistaken. Member Since: August 14, 2008 Posts: 0 Comments: 508

608. PensacolaDoug 12:13 PM GMT on October 08, 2010
Quoting BobinTampa: I usually love the cold weather. but last year, even I was saying 'enough!!!' I think we had well over a week of highs in the 50's if I'm not mistaken. We kept getting forecast after forecast for a little snow last year here in P'cola. It never materialized here except for one 2 minute period where we had some big flakes mix in right as the rain was ending. Cold w/o snow is just a big waste of cold to me! Member Since: July 25, 2006 Posts: 0 Comments: 4831

610. stormwatcherCI 12:15 PM GMT on October 08, 2010
Quoting Dakster: Yep. Even JFV/Weatherstudent was pleasant back then... I think I would rather see him on here than the vulgar ones who are coming on now. Member Since: October 9, 2008 Posts: 0 Comments: 8058

612. stillwaiting 12:20 PM GMT on October 08, 2010
Quoting pottery: Dont think you are going to get one in the near future... Hope you get some showers though, sounds unpleasant... .....actually the wx here is awsome, just dry,butw/highs in the low 80's,little to no humudity its been a early fall treat for our area,however if it continues this dry we are going to have alot of problems as our fire season approaches(winter months)....but yea,we could use rain in any form,as we're already below ave for precip this y!!! Member Since: October 5, 2007 Posts: 20 Comments: 4970

613. hydrus 12:22 PM GMT on October 08, 2010
Another awesome day in da Gulf... Member Since: September 27, 2007 Posts: 1 Comments: 14682

616. TampaTom 12:27 PM GMT on October 08, 2010
Quoting hydrus: Another awesome day in da Gulf... Beautimus morning in Clearwater, FL... Member Since: June 20, 2005 Posts: 22 Comments: 1049

617. PensacolaDoug 12:29 PM GMT on October 08, 2010
Dry as a bone down here tho! Member Since: July 25, 2006 Posts: 0 Comments: 4831

618. hydrus 12:30 PM GMT on October 08, 2010
Quoting FLstormwarning: Good Morning Guys! After Otto what's next. Paula. Member Since: September 27, 2007 Posts: 1 Comments: 14682

619. kmanislander 12:31 PM GMT on October 08, 2010
Good morning all The models are not handling the conditions in the SW Caribbean very well but that is to be expected as nothing has formed there yet and upper level winds are not currently conducive for development. Several of the models keep hinting at development but none are bullish on it from recent runs. Typically at this time of year it takes several days for anything to coalesce into an organized system in the SW Caribbean. For now, I don't see anything taking shape down there while shear remains high in the region. With the exception of a small pocket of low shear in the extreme SW Caribbean conditions are too hostile for development any time soon. Member Since: August 19, 2006 Posts: 0 Comments: 14988

620. HurricaneDean07 12:32 PM GMT on October 08, 2010
There is some definate strengthening going on with Otto. On sat. loop it shows a eye beginning to form Member Since: October 3, 2010 Posts: 40 Comments: 4129

621. hydrus 12:32 PM GMT on October 08, 2010
Quoting TampaTom: Beautimus morning in Clearwater, FL... I love it there. We would party hearty on the pier in the late 70,s and early 80,s...Good times indeed. Member Since: September 27, 2007 Posts: 1 Comments: 14682

622. stillwaiting 12:33 PM GMT on October 08, 2010
Quoting pottery: Dont think you are going to get one in the near future... Hope you get some showers though, sounds unpleasant... Quoting aislinnpaps: The whole state of Louisiana has been under one for several days now. We're the second driest state in the country right now. ...a warning or watch, i had a watch and the upgraded it to a warning for today,last night... Member Since: October 5, 2007 Posts: 20 Comments: 4970

623. hydrus 12:36 PM GMT on October 08, 2010
Quoting cat5hurricane: Yes sir. Could not agree more. Did you make a prediction for the number of tropical cyclones this year? I went with 15/10/5...I thought 3 of the majors would reach cat-5 with all the warm water out there..I got 0 so far.! Igor was only 1 mph from the mark though.. Member Since: September 27, 2007 Posts: 1 Comments: 14682

624. WeatherMum 12:37 PM GMT on October 08, 2010
Quoting PensacolaDoug: We kept getting forecast after forecast for a little snow last year here in P'cola. It never materialized here except for one 2 minute period where we had some big flakes mix in right as the rain was ending. Cold w/o snow is just a big waste of cold to me! Funny, I have video of my son dancing in that "snow". We was screaching like he'd never seen the 20 foot drifts of NoDak! LOL! Member Since: February 12, 2007 Posts: 0 Comments: 118

627. Neapolitan 12:45 PM GMT on October 08, 2010
The dryness here at the southern tip of Florida is--very thankfully--ending soon. Humidity levels and rain chances are finally forecast to return to normal (and even above normal) by Sunday as that nasty arid airmass vacates to the east. Too, highs for Naples over the next week are expected to be in the upper 80s to near 90, with lows around 70. (And I see that along the northern Gulf coast, the humidity will return on Monday, along with a chance of rain.) With the blocking trough of dessicated atmosphere finally moving away, it appears the fat lady has been forced back to her dressing room, where she'll have nothing to do but sit and do vocal exercises for at least another week or more...any by then, who knows how things will be? The long-range models show more highs and more cold fronts in the future, but that's to be expected; it is October, after all. Of note, though, not a single global model shows anything remotely resembling the current Southern Sahara setting up anytime soon. Member Since: November 8, 2009 Posts: 4 Comments: 11302

628. FtMyersgal 12:45 PM GMT on October 08, 2010
Quoting TampaTom: Beautimus morning in Clearwater, FL... Same Beautimus morning here in Fort Myers. Very unusual weather for this early in October. I am loving it! Member Since: September 16, 2010 Posts: 0 Comments: 1053

629. WeatherMum 12:46 PM GMT on October 08, 2010
OK y'all. I'm taking the day off, and hanging out the "gone fising" sign. Heading out onto the GOM for the day. Y'all behave! Member Since: February 12, 2007 Posts: 0 Comments: 118

633. hydrus 12:50 PM GMT on October 08, 2010
Quoting cat5hurricane: No, I didn't. I try not to place too much value in forecasts that are very far off in the distance. Usually though, I don't find too much disagreement with the NHC prediction...& this years outlook was no exception. Igor was SO CLOSE! He sure made a run for it! Although I have a feeling they might upgrade him in the future since I don't even think recon had a chance to fly in there at his peak... I was thinking that too..They may re-evaluate Alex also... Member Since: September 27, 2007 Posts: 1 Comments: 14682

637. TropicalAnalystwx13 12:56 PM GMT on October 08, 2010
In my opinion they will re-evaluate: Alex to 115 mph Earl to 150/155 mph Hermine to 70/75 mph Igor to 160 mph Member Since: July 6, 2010 Posts: 92 Comments: 25956

640. stillwaiting 1:07 PM GMT on October 08, 2010
Quoting PensacolaDoug: We kept getting forecast after forecast for a little snow last year here in P'cola. It never materialized here except for one 2 minute period where we had some big flakes mix in right as the rain was ending. Cold w/o snow is just a big waste of cold to me! .......i know in srq we had a few days w/highs in the low-mid 40's,one morning it was 34* and raining here on siesta key!!!!,so close to snow!!!!,i think their was a little sleet mixed in down here but no snow,it was pretty cool to see the white on my local radar just north of tpa.......our high that day was. in the upper 30's i believe.... Member Since: October 5, 2007 Posts: 20 Comments: 4970

641. Orcasystems 1:09 PM GMT on October 08, 2010
Quoting PensacolaDoug: We kept getting forecast after forecast for a little snow last year here in P'cola. It never materialized here except for one 2 minute period where we had some big flakes mix in right as the rain was ending. Cold w/o snow is just a big waste of cold to me! KOG figures he has the machine fixed.. its possible he might do a better job this year :) Member Since: October 1, 2007 Posts: 77 Comments: 26110

643. Neapolitan 1:18 PM GMT on October 08, 2010
Interestinger and interestinger... Click for larger image: Member Since: November 8, 2009 Posts: 4 Comments: 11302

646. IKE 1:24 PM GMT on October 08, 2010
Quoting Neapolitan: The dryness here at the southern tip of Florida is--very thankfully--ending soon. Humidity levels and rain chances are finally forecast to return to normal (and even above normal) by Sunday as that nasty arid airmass vacates to the east. Too, highs for Naples over the next week are expected to be in the upper 80s to near 90, with lows around 70. (And I see that along the northern Gulf coast, the humidity will return on Monday, along with a chance of rain.) With the blocking trough of dessicated atmosphere finally moving away, it appears the fat lady has been forced back to her dressing room, where she'll have nothing to do but sit and do vocal exercises for at least another week or more...any by then, who knows how things will be? The long-range models show more highs and more cold fronts in the future, but that's to be expected; it is October, after all. Of note, though, not a single global model shows anything remotely resembling the current Southern Sahara setting up anytime soon. ?????? ..................................... Miami,FL. forecast for the next 7 days... Today: Sunny, with a high near 84. Northeast wind between 9 and 13 mph. Tonight: Partly cloudy, with a low around 71. Northeast wind between 7 and 10 mph. Saturday: Mostly sunny, with a high near 85. North wind between 7 and 11 mph. Saturday Night: Partly cloudy, with a low around 73. Northeast wind between 6 and 10 mph. Sunday: Mostly sunny, with a high near 85. Northeast wind between 6 and 9 mph. Sunday Night: Partly cloudy, with a low around 72. East wind around 8 mph. Columbus Day: Mostly sunny, with a high near 85. East wind between 6 and 10 mph. Monday Night: Isolated showers. Partly cloudy, with a low around 74. East wind around 9 mph. Chance of precipitation is 10%. Tuesday: A 10 percent chance of showers. Mostly sunny, with a high near 85. East wind between 8 and 13 mph. Tuesday Night: A 10 percent chance of showers. Partly cloudy, with a low around 74. Wednesday: A 10 percent chance of showers. Mostly sunny, with a high near 85. Wednesday Night: A 10 percent chance of showers. Partly cloudy, with a low around 74. Thursday: A 20 percent chance of showers. Mostly sunny, with a high near 85. .............................................. Fort Myers,FL... Today: Sunny, with a high near 86. Northeast wind between 6 and 9 mph. Tonight: Clear, with a low around 62. North northwest wind around 6 mph becoming calm. Saturday: Sunny, with a high near 87. Calm wind becoming north northwest between 5 and 8 mph. Saturday Night: Clear, with a low around 63. Northwest wind around 6 mph becoming calm. Sunday: Sunny, with a high near 88. Calm wind becoming northeast between 5 and 8 mph. Sunday Night: Partly cloudy, with a low around 66. North northwest wind between 5 and 7 mph. Columbus Day: Mostly sunny, with a high near 89. Light east northeast wind. Monday Night: Partly cloudy, with a low around 65. East wind between 3 and 6 mph. Tuesday: Mostly sunny, with a high near 89. East northeast wind around 5 mph becoming calm. Tuesday Night: Partly cloudy, with a low around 68. Wednesday: Mostly sunny, with a high near 88. Wednesday Night: Partly cloudy, with a low around 65. Thursday: Mostly sunny, with a high near 85. ............................................... Orlando,FL... Today: Sunny, with a high near 85. West wind around 5 mph. Tonight: Clear, with a low around 59. East northeast wind around 5 mph becoming calm. Saturday: Sunny, with a high near 88. Calm wind becoming north around 5 mph. Saturday Night: Mostly clear, with a low around 62. East northeast wind around 5 mph becoming calm. Sunday: Sunny, with a high near 88. Calm wind becoming northeast around 5 mph. Sunday Night: Mostly clear, with a low around 64. Southeast wind around 5 mph. Columbus Day: Mostly sunny, with a high near 87. North northwest wind around 5 mph becoming calm. Monday Night: Partly cloudy, with a low around 65. South southeast wind around 5 mph. Tuesday: Mostly sunny, with a high near 87. Calm wind. Tuesday Night: Mostly clear, with a low around 65. East wind around 5 mph becoming southwest. Wednesday: Mostly sunny, with a high near 86. West northwest wind around 5 mph becoming calm. Wednesday Night: Partly cloudy, with a low around 65. East northeast wind around 5 mph becoming southwest. Thursday: A 20 percent chance of showers. Mostly sunny, with a high near 83. Calm wind becoming west northwest around 5 mph. ............................................... Tampa,FL... Today: Sunny, with a high near 85. North northwest wind between 3 and 5 mph. Tonight: Clear, with a low around 60. North northwest wind around 5 mph becoming calm. Saturday: Sunny, with a high near 87. Calm wind becoming west around 6 mph. Saturday Night: Clear, with a low around 63. North northwest wind between 4 and 7 mph becoming calm. Sunday: Sunny, with a high near 87. Calm wind becoming southwest around 5 mph. Sunday Night: Partly cloudy, with a low around 66. North northwest wind between 3 and 5 mph. Columbus Day: Mostly sunny, with a high near 87. Calm wind. Monday Night: Partly cloudy, with a low around 67. North northwest wind between 3 and 6 mph. Tuesday: Mostly sunny, with a high near 87. Light and variable wind. Tuesday Night: Partly cloudy, with a low around 67. Wednesday: Mostly sunny, with a high near 86. Wednesday Night: Partly cloudy, with a low around 67. Thursday: Mostly sunny, with a high near 85. Member Since: June 9, 2005 Posts: 23 Comments: 37070

647. KEEPEROFTHEGATE (Mod) 1:26 PM GMT on October 08, 2010
17L/H/O/C1 MARK 25.98N/64.49W THREAT TO SHIPPING ONLY Member Since: July 15, 2006 Posts: 147 Comments: 41318

649. RitaEvac 1:29 PM GMT on October 08, 2010
Mother nature has thrown a few ice cubes into the glass Member Since: July 14, 2008 Posts: 1 Comments: 8953

650. KEEPEROFTHEGATE (Mod) 1:34 PM GMT on October 08, 2010
LATEST VIS 1KM STILL Member Since: July 15, 2006 Posts: 147 Comments: 41318

651. hydrus 1:37 PM GMT on October 08, 2010
Quoting RitaEvac: Mother nature has thrown a few ice cubes into the glass Yes..Quite a difference from a month ago..Still looks warm on this map though... Member Since: September 27, 2007 Posts: 1 Comments: 14682

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