TD 16 organizing; Mexican landslide kills hundreds; hottest day ever in Los Angeles

By: Dr. Jeff Masters , 7:25 PM GMT on September 28, 2010

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The large area of low pressure centered just south of Cuba's Isle of Youth has developed enough of a well-defined circulation to be classified as Tropical Depression Sixteen, and is likely to become Tropical Storm Nicole by Wednesday. The depression has a very broad center, with little heavy thunderstorm activity near the center, and is this very dissimilar to the usual types of tropical depressions we see in the Atlantic. The large size, broad center, and lack of heavy thunderstorm activity near the center of TD 16 will limit the storm's ability to rapidly intensify. TD 16 resembles the "monsoon depressions" common in India's Bay of Bengal or the Western Pacific. A monsoon depression is similar to a regular tropical depression in the winds that it generates--about 30 - 35 mph near the outer edges (and usually stronger on the eastern side of the circulation.) Monsoon depressions have large, calm centers, and can evolve into regular tropical storms, if given enough time over water to develop a tight, closed circulation. Today's monsoon-like depression in the Caribbean was able to form because the atmospheric flow pattern of the Eastern Pacific has shifted eastwards into the Western Caribbean, bringing in the Eastern Pacific ITCZ (Intertropical Convergence Zone, a region of converging surface winds that creates a band of strong thunderstorms). This unusual flow pattern is forecast to remain in place for at least the next ten days.

An Air Force hurricane hunter aircraft has been flying at 700 feet in TD 16 since 1:30pm EDT, and has thus far found a central pressure of 999 mb. The strongest winds at flight level seen as of 3:20pm EDT were 32 mph, located about 100 miles east of the center of TD 16. Surface observations show that the strongest winds at any surface station continue to be at Buoy 42057, several hundred miles to the southeast of TD 16's center. Winds were 27 mph, gusting to 34 mph at 2:43pm EDT this afternoon. Rotation of TD 16 can be seen on radar loops out of Pico San Juan, Cuba, and well as satellite imagery. The heavy thunderstorms are currently quite disorganized, but a curved band is beginning to wrap around the north side of the center, signaling that TD 16 is growing more organized. TD 16 has brought torrential rains to the Cayman Islands, Jamaica, Cuba, and Honduras today.


Figure 1. Radar-estimated precipitation for South Florida and Cuba. TD 16 has brought 2 - 4 inches of rains to the region.

Forecast for TD 16
Because TD 16 is so large, it will take more time than a typical depression for it to spin up into a strong tropical storm. Given that the steering currents are expected to pull TD 16 north-northeastwards over Cuba and into South Florida and the western Bahamas on Wednesday, the storm lacks sufficient time over water to be any stronger than a 50 mph tropical storm for Florida. TD 16 is organizing pretty slowly this afternoon, and I think the top winds in Southeast Florida are most likely to be in the 25 - 35 mph range on Wednesday. Winds are likely to be stronger in the western Bahamas, perhaps 30 - 40 mph, since they will be in the stronger right front quadrant of the storm. By the time TD 16 makes landfall in South Carolina or North Carolina on Thursday morning, it could be as strong as a 50 - 60 mph tropical storm. However, wind shear will increase sharply on Thursday as TD 16 gets caught in an upper-level trough of low pressure, and NHC is giving TD 16 only a 9% chance of making it to hurricane strength before it becomes an extratropical storm on Thursday. The primary danger from TD 16 is not wind, but heavy rainfall. A potent upper-level low and stationary front over the U.S. East Coast have been pulling moist, tropical air from the Caribbean northwards over the past few days, bringing heavy rains that have saturated the soils. This is called a Predecessor Rain Event, or PRE, since it comes in advance of the actual rain shield of the storm. (A PRE from Hurricane Karl brought southern Wisconsin the heavy rain that caused the levee on the Wisconsin River to fail yesterday.) Wilmington, NC received 10.33 inches of rain yesterday, its second greatest one-day rainfall since record keeping began in 1871. Only the 13.38" that fell during Hurricane Floyd on September 15, 1999 beat yesterday's rainfall total. With TD 16 expected to bring another 6 - 8 inches of rain to the region later this week, serious flooding is likely, and flash flood watches are posted for the North Carolina/ South Carolina border region. South Florida is also under a flood watch, for 3 - 5 inches of rain. Flooding rains of similar magnitude can also be expected in Cuba, the Cayman Islands, and the Western Bahamas through Wednesday night. Both the GFDL and HWRF models are predicting that TD 16 will dump rains in excess of eight inches along narrow portions of its path in eastern Florida, South Carolina, and North Carolina.


Figure 2. Forecast precipitation for the 5-day period from 8am today through 8am EDT Sunday, October 3, 2010. Image credit: NOAA Hydrometeorological Prediction Center.

Up to 1,000 feared dead in Mexican landslide
Mexico has taken the brunt of the devastation from the hurricane season of 2010, thanks to the landfalls of this year's two deadliest and most damaging storms, Hurricanes Alex and Karl. But Mexico's worst blow yet hit this morning, when heavy rains from the remnants of Tropical Storm Matthew triggered a landslide in Mexico's mountainous Oaxaca state that buried as many as 1,000 people in Santa Maria Tlahuitoltepec, a town of 9,000. Rescuers have not reached the area yet, but hundreds are feared dead in the 300 homes that were buried by the early morning landslide. Matthew hit Belize on Saturday as a minimal tropical storm with 40 mph winds, and dissipated Sunday over southern Mexico. However, Matthew's remains stalled out over the region of Mexico that had already received torrential rains from Hurricane Karl, which hit on September 18. Satellite estimates of Matthew's rains over southern Mexico (Figure 3) show that a foot of rain may have fallen in the landslide area. Matthew's remains still linger over the region, but are probably only capable of bringing 1 - 2 inches of additional rain through Thursday.


Figure 3. Satellite-estimated rainfall for the five-day period ending at 8pm EDT Monday September 27, 2010. The dark green colors show where rainfall amounts of 300 mm (about 12 inches) fell, due to the remnants of Tropical Storm Matthew. Image credit: Navy Research Lab, Monterey.

Elsewhere in the tropics
Once TD 16 moves out of the Caribbean, the GFS model predicts that the Western Caribbean will "reload" and produce another tropical disturbance capable of developing into a tropical depression early next week. The GFS also predicts a tropical or subtropical storm will form over the Bahamas late this week, and move north-northeast along the U.S. East Coast, missing hitting land. The NOGAPS model hints at the Bahamas storm, and also predicts development of a tropical wave a few hundred miles northeast of the Lesser Antilles Islands, about a week from now.

Hottest day in Los Angeles history
The mercury hit a blistering 113°F (45.0°C) at 12:15 pm PDT yesterday in downtown Los Angeles, making it the hottest day in Los Angeles history. It may have gotten hotter, but the thermometer broke shortly after the record high was set. The previous record in Los Angeles was 112°F set on June 26, 1990; records go back to 1877. Nearby Long Beach tied its hottest all-time temperature yesterday, with a scorching 111°F. And Christopher C. Burt, our new featured blogger on weather records, pointed out to me that a station in the foothills at 1260' elevation near Beverly Hills owned by the Los Angeles Fire Department hit 119°F yesterday--the hottest temperature ever measured in the Los Angeles area, tying the 119°F reading from Woodland Hills on July 22, 2006. Yesterday's record heat was caused by an unusually large and intense upper-level high pressure system centered over Nevada that generated winds blowing from the land to the ocean, keeping the ocean from exerting its usual cooling influence. Remarkably, Los Angeles had its second coldest summer on record this year, and temperatures just five days ago were some the coldest September temperatures in the region for the past 50 years.

The remarkable summer of 2010
Wunderground is pleased to welcome a new featured blogger--weather historian Christopher C. Burt. Chris is a leading expert in the U.S. on weather records, and is author of the world's most popular weather records book published to date, Extreme Weather: A Guide and Record Book. He's spent a lifetime collaborating with like-minded individuals from around the world, and no one--including official sources such as the National Climatic Data Center and the National Extremes Committee--has done as thorough a job correlating the various weather records available and determining the most accurate extreme values of such. Each month he'll be reporting on the notable records for heat, cold, and precipitation set world-wide, and his first post takes a look at the remarkable summer of 2010. It's great to have someone like Chris who stays on top of weather extremes, and I hope you'll pay a visit to his blog and welcome him to the wunderground site!

"Hurricane Haven" airing this afternoon
My live Internet radio show, "Hurricane Haven", will be airing again today at 4pm EDT. The call in number is 415-983-2634, or you can post a question to broadcast@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line.

Today's show will be about 30 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

I'll have updates as the situation with TD 16 requires.

Jeff Masters

Alone again, naturally (ftogrf)
Lonely Seagull, as a storm associated with TD 16 is approaching.
Alone again, naturally

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i have a gut feeling TD 16 will consolidate tonight and moving over south florida as a 50-55 Mph Tropical storm
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Quoting leo305:


actually the air temperature and whether its a cold core a warm core system does have alot to do with whether or not it's a subtropical or tropical system..


right but that is not dictated by SSTs
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Ensemble Tropical Rainfall Potential (eTRaP)

2010-09-28 18Z eTRaP for SIXTEEN

Update for 2010-09-29 00Z is due at 03Z
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Hurricane Alex back in June had max winds a couple hundred miles east of the center back when he was developing in the Caribbean.
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Quoting Stormchaser2007:
Im well-aware that it is not sub-tropical



yup me too
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Quoting Hurricanes101:


I disagee with SSTs having anything to do with whether something can be tropical or sub-tropical


actually the air temperature and whether its a cold core a warm core system does have alot to do with whether or not it's a subtropical or tropical system..
Member Since: April 17, 2010 Posts: 0 Comments: 1753
Im well-aware that it is not sub-tropical

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AL162010 SIXTEEN for Run: 2010-09-28 18Z

Multiplatform Tropical Cyclone Surface Winds Analysis (MTCSWA)

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Quoting weatherman12345:

why dont they cancel schools. with gusts of 55 mph they arent allowed to send the buses out for liability reasons


Volusia County once cancelled school only on the east side of the county along the intercoastal and the beach, the rest of us did not get the day off :(
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Quoting Levi32:


Take a vacation to the Philippines and you'll see monsoon depressions like this every day. I guess they're subtropical too because their max winds are 100-200 miles away from the center?


That is not a fair comparison due to the fact that most systems in the WPAC are larger in size than they are here regardless of what kind of development it is
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Quoting mcluvincane:


STD don't think so


Quoting Seastep:


It was at 3:45EDT and was a mistake.

ATCF reversed it shortly thereafter.



It was a sad attempt at some humor.
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this may be the 8th name storm for SEP the last time we did this was back in 2007
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Quoting MiamiHurricanes09:
Yes, because it's monsoonal. Systems of that nature tend to have winds displaced from their circulation. Please show me of one subtropical cyclone that formed over the northwestern Caribbean during the month of late September (whilst siting over 30C sea surface temperatures)?


again if SSTs were a big indicator then we would never see Sub Tropical systems in the Gulf of Mexico or the Gulf Stream; nor would we see Tropical systems out near 40N in the Atlantic.
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ESL by LSU TD-16 Page
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Quoting Hurricanes101:


stronger winds away from the center

I think it could qualify, we have seen Sub-tropical systems in the Gulf with waters below it very warm


Take a vacation to the Philippines and you'll see monsoon depressions like this every day. I guess they're subtropical too because their max winds are 100-200 miles away from the center? That's how they roll...
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Quoting Stormchaser2007:
28/1745 UTC 20.8N 83.2W ST2.5 16L

STD16?


It was at 3:45EDT and was a mistake.

ATCF reversed it shortly thereafter.
Member Since: September 9, 2008 Posts: 6 Comments: 3414
Quoting Hurricanes101:


stronger winds away from the center

I think it could qualify
Yes, because it's monsoonal. Systems of that nature tend to have winds displaced from their circulation. Please show me of one subtropical cyclone that formed over the northwestern Caribbean during the month of late September (whilst siting over 30C sea surface temperatures)?
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Quoting Stormchaser2007:
Be weary of STD16.

(It's the redish-purple blob)



STD don't think so
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Quoting Stormchaser2007:
Be weary of STD16.


By the time all is said and done, I'm sure many will be.
Member Since: August 21, 2007 Posts: 0 Comments: 856
Quoting MiamiHurricanes09:
2010092818 CIRA/NESDIS AMSU-based al162010 analysis cyclone phase evolution.



I disagee with SSTs having anything to do with whether something can be tropical or sub-tropical
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I don't care about the forecast for subtropical....it's initialized as warm-core by the models too. This is not a subtropical system in the Caribbean right now. It is forming from tropical processes. It will begin feeling baroclinic enhancement when it moves north but not right now.

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Good evening everyone... strange day in Delray Beach just north of Boca Raton... sunny most of the day... just watch the rain cruise up the coast... at five, it was like flipping a switch... wind picked up...got dark... and it was raining sideways.
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Quoting Hurricanes101:


I disagree
2010092818 CIRA/NESDIS AMSU-based al162010 analysis cyclone phase evolution.

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Quoting Levi32:


It's not subtropical lol....it will be baroclinically enhanced later, but is not doing so now. It's a monsoon trough in the Caribbean in September....honestly?

ST numbers were coming in at 12z this morning and they still called it tropical so good for the NHC, but I think in the end they will strip it of its name for lame reasons before it even does its worst damage in the Carolinas.


stronger winds away from the center

I think it could qualify, we have seen Sub-tropical systems in the Gulf with waters below it very warm
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multi-cellular convective rapid firing cells are an indication of possible rapid development
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Quoting A4Guy:
this is one of the poorest looking tropical cyclones I have seen. As i said earlier, i would not be surprised if this system degraded into an open wave within the next update or two. There is almost nothing happening at the center...and the "center" is a very loose term at this point.


it ain't exactly that kinda system...
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Be weary of STD16.

(It's those redish-purple blobs)

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Cat5: Mine is a COCORAHS gauge, so we shall see. I dont think the 8 inches will all come in one day, so it should work (unless we are closer to the 11 inch totals!).

Press and Nash, thanks for the welcome. Been in the area since January.
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Quoting Hurricanes101:


hence the appearance of this system

the fact that it could be sub-tropical, means to me this will be a bit stronger than forecast due to not being impacted as much by windshear


It's not subtropical lol....it will be baroclinically enhanced later, but is not doing so now. It's a monsoon trough in the Caribbean in September....honestly?

ST numbers were coming in at 12z this morning and they still called it tropical so good for the NHC, but I think in the end they will strip it of its name for lame reasons before it even does its worst damage in the Carolinas.
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Quoting weatherman12345:
just sayin its odd to see a pressure so low in a TD.

This monsoon flow is from the E Pacific. Due to La Nina and the change in the upper air patterns, the monsoon pattern that is usually over the E Pacific is now over the W Caribbean Sea.

The sprawling area of Low pressure is a very broad and there is a lower pressure over the entire region. That is why we have a 998MB TD. Also wind shear is about 20+ KTS keeping the deepest convection over the SE quadrant keeping the system from consolidating.

The unfortunate part of this is we could have several tropical disturbances develop in this same region for at least the next 2 weeks.
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900. A4Guy
this is one of the poorest looking tropical cyclones I have seen. As i said earlier, i would not be surprised if this system degraded into an open wave within the next update or two. There is almost nothing happening at the center...and the "center" is a very loose term at this point.
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Quoting MiamiHurricanes09:
SAB thinks it's subtropical. LOL. No way that a cyclone sitting over 30C waters could be subtropical.


I disagree
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NHC TAFB Experimental Graphicast

This is the experimental Graphical Forecast (Graphicast) produced by NHC's Tropical Analysis and Forecast Branch. It is a graphical weather depiction that will highlight primary weather features of interest. The image is experimental and has planned updates once per day in the early afternoon.

If you have questions or comments about this new feature, please complete the contact form below. Comments will be accepted through October 20, 2010.
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Quoting Stormchaser2007:
28/1745 UTC 20.8N 83.2W ST2.5 16L

STD16?
Wow, that's a lot...
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Quoting StormHype:


why? Is Cantore hyping it while Norcross is pooping on his parade saying this is going to be pretty lame?


no..

bryan is saying not to down play the system.. saying that he's seen a lot of carribean systems form like this and dump a huge amount of rain on the east side of the center.. so if it moves west of miami, it could be a bad situation in terms of flooding..

and he's like LOOK THERE'S NO WIND, THERE'S NOTHING, IS THIS A BUST OR NOT A BUST? WHAT DO YOU THINK?!

and.. if you look at it.. the system is still 350 freakin miles away from ft laudaradale.. and he acts as if the center is right over them.. -_-
Member Since: April 17, 2010 Posts: 0 Comments: 1753
Quoting Tazmanian:
09 look at this

28/1745 UTC 20.8N 83.2W ST2.5 16L -- Atlantic
SAB thinks it's subtropical. LOL. No way that a cyclone sitting over 30C waters could be subtropical.
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Quoting Stormchaser2007:
28/1745 UTC 20.8N 83.2W ST2.5 16L

STD16?


hence the appearance of this system

the fact that it could be sub-tropical, means to me this will be a bit stronger than forecast due to not being impacted as much by windshear
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Quoting MiamiHurricanes09:
For Miami:

Wednesday:
Tropical storm conditions possible. Periods of rain and isolated thunderstorms. Rain may be heavy at times. Highs in the mid 80s. East winds 30 to 35 mph becoming southeast 25 to 30 mph in the afternoon. Gusts up to 55 mph. Chance of rain near 100 percent.



Better get your water boots ready !!!!!
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Quoting Stormchaser2007:
28/1745 UTC 20.8N 83.2W ST2.5 16L

STD16?


LOL!
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Quoting Torgen:
hey guys, did the track shift west a bit on the 5pm update? I'm trying to decide if I need to head into downtown Tampa early tomorrow for my hospital visit.




you can read back a few page and you can find out
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Quoting Stormchaser2007:
28/1745 UTC 20.8N 83.2W ST2.5 16L

STD16?




the T # came in at ST so with 2.5 it would be a STS
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hey guys, did the track shift west a bit on the 5pm update? I'm trying to decide if I need to head into downtown Tampa early tomorrow for my hospital visit.
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09 look at this

28/1745 UTC 20.8N 83.2W ST2.5 16L -- Atlantic
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28/1745 UTC 20.8N 83.2W ST2.5 16L

STD16?
Member Since: Posts: Comments:

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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.