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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Quoting Grothar:
Anybody in the Ft. Lauderdale area notice there are no birds around?


Still have my Blue Jays and Dove coming in the backyard. Am located out in west Broward (Plantation)
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Quoting CybrTeddy:


Careful when estimating that, the Recon was flying pretty close to sea level, 200 meters or so.


well then woudlnt that mean the surface winds would be a bit higher since those observations were closer to the surface?
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Quoting Jedkins01:
The latest computer guidance has shifted back west. Although it is unlikely, I would this thing would bring a rain core over pinellas county, after getting a soaking 20+ inches in August, we can't even BUY a drop of rain here in September! WE were supposed to get a lot of rain since friday, but none of it materialized whatsoever. Today there is FINALLY some good storm coverage, but sadly, once again, its all missing Pinellas county, again.

This might be near the driest september ever here!



At any rate, I hope the model shift to the west will be right, an little extra rain would nice before it dries out all together...
The models aren't currently anticipating THAT much of a shift to the west. As long as the storm passes to your east, you won't get much of anything at all.
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Not over just yet?
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I see the COC of td#16 at around 20.5N /84W on visible , anyone else see this?
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Quoting stormpetrol:
I can't believe this a pressure of 999mb in Grand Cayman and winds SSW @4mph.
You are in the giant center of the monsoonal low...:0
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Quoting CycloneUK:

That wave east of the islands isnt a threat to develop yet but it may once it enters the carribean....on the other note expect that convection to wane again
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Quoting Seastep:
From 220° at 36 knots
(From the SW at ~ 41.4 mph)

Flight level. Surface = 37mph


Careful when estimating that, the Recon was flying pretty close to sea level, 200 meters or so.
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A blogger here had mentioned that he/she thought that the front was retreating. If that is so, that may explain some of the models trending west. Also, looking at the visible sat, floater. It looks as though it's just spinning around the Isl or youth and not moving much at all. So, if indeed the front has stalled or is retreating then that could cause a stall or northward movement. imo
NHC has it moving nne to ne at this time
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News Channel 25 WPBF is Showing a Shot of Boca Raton Florida..

0 Visibilty on the Highway.
Member Since: June 17, 2006 Posts: 44 Comments: 5010
Are there two centers?
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From 220° at 36 knots
(From the SW at ~ 41.4 mph)

Flight level. Surface = 37mph
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they are now finding flight level winds of TS force well south of the center, but they still do not have the surface winds turned on
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Whew!!! Los Angeles is no where as hot as yesterday only 94 degrees now compared to 112 at this time yesterday.
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The latest computer guidance has shifted back west. Although it is unlikely, I would this thing would bring a rain core over pinellas county, after getting a soaking 20+ inches in August, we can't even BUY a drop of rain here in September! WE were supposed to get a lot of rain since friday, but none of it materialized whatsoever. Today there is FINALLY some good storm coverage, but sadly, once again, its all missing Pinellas county, again.

This might be near the driest september ever here!



At any rate, I hope the model shift to the west will be right, an little extra rain would nice before it dries out all together...
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I can't believe this a pressure of 999mb in Grand Cayman and winds SSW @4mph.
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Quoting Dakster:


I thought they locked the bridges DOWN, preventing you from moving a large boat by water. (as opposed to towing it with a vehicle).
I guess it would impact the Islamorada area, which is the only drawbridge left in the keys over Snake Creek. Otherwise all our bridges are a lot higher up so no draw bridges are necessary.
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schools in dade county?
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Quoting Grothar:
Anybody in the Ft. Lauderdale area notice there are no birds around?

Uh oh, no birds around is not good. They leave when they "feel" a storm coming. Sometimes Mother Nature knows more than all the computer models. All we can do is wait and watch.
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Quoting FSUCOOPman:


Dr. M just said on his talkshow that flight level were 36 mph, so much lower at the surface.


Not "much" lower. Just 10%. So 36 flight = 32 surface.
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they usual high tail it outta here when storm bearing down on area...

Quoting Grothar:
Anybody in the Ft. Lauderdale area notice there are no birds around?
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Member Since: June 17, 2006 Posts: 44 Comments: 5010
Quoting newportrinative:


Nope, some just flew by and I have my usual cast of characters on the telephone pole behind us.


Wind is Gusting Here, and Heavy Rain Band here in South Palm Beach County...

Its Pouring...
Member Since: June 17, 2006 Posts: 44 Comments: 5010
PB County announcing at 5:00 re closures or not. I expect no school.
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Quoting Hurricanes101:


That is not the same thing

they are saying recon is not finding TS force winds, they are not mentioning at all about anything being wrong with the observations on board

that is what I am saying

Oh? My apologies. I am not nearly as knowledgeable as any of you with this stuff.
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Member Since: August 17, 2010 Posts: 21 Comments: 6939
Quoting Seflhurricane:
it is just about at TS status , it will be upgraded at 5Pm what are you hearing !!!!!

I was very surprised to hear him say that which is why I posted that with an exclamation point. Not sure of his thinking. He sort of threw that in there at the end as a by-the-way in answering a question.
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Quoting Grothar:
Anybody in the Ft. Lauderdale area notice there are no birds around?


Nope, some just flew by and I have my usual cast of characters on the telephone pole behind us.
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Quoting Seflhurricane:
how strong are the winds that recon is finding


Dr. M just said on his talkshow that flight level were 36 mph, so much lower at the surface.
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Quoting CybrTeddy:


TCHP isn't all that counts, there is dry, cool air plunging into the circulation that is causing it to be very sub-tropical. 50 mph peak at best.


there isn't any dry/cool air over the southern GULF OF MEXICO..

the cold front is falling apart, and a warm front is developing over central florida..


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San Fran Hotter than NOLA right now.. San Fran 94F, Nola 79F
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Quoting TOMSEFLA:
recon never sent a vortex report????

They aren't done just yet.
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Quoting yacoub:

Was it a spelling bee?


Ok, now THAT'S funny!!

+1
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Quoting Neapolitan:
Hurricane Haven was excellent today, as usual, but Dr. Masters made one slight factual error when he stated that no major hurricane had ever struck Texas after September 30th; the 1949 Texas Hurricane made landfall near Freeport as a Cat 4 on October 3rd of that year. Just so you north coasters know that you're not completely out of the woods yet... ;-)


Good Job, Gold Star.

Your starting to really shape up as a young man.
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recon never sent a vortex report????
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Anybody in the Ft. Lauderdale area notice there are no birds around?
Member Since: July 17, 2009 Posts: 71 Comments: 26825
Hurricane Haven was excellent today, as usual, but Dr. Masters made one slight factual error when he stated that no major hurricane had ever struck Texas after September 30th; the 1949 Texas Hurricane made landfall near Freeport as a Cat 4 on October 3rd of that year. Just so you north coasters know that you're not completely out of the woods yet... ;-)
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Quoting CybrTeddy:


TCHP isn't all that counts, there is dry, cool air plunging into the circulation that is causing it to be very sub-tropical. 50 mph peak at best.


Not to mention how quickly the storm is moving
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Quoting chrisdscane:
it still remains disorganized

post 210 explains it.
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Quoting yacoub:

Was it a spelling bee?


LOL WIN!
Member Since: June 17, 2006 Posts: 44 Comments: 5010
235. unf97
Quoting Clearwater1:
yes indeed. And a significance shift left may mean more intensity.


Possibly. But I don't see this being more than a 45 knot moderate tropcial cyclone at best. I think the system is too lopsided in structure.
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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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