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 presslord:
Hey Tigg!!!!!!!!!!! Breezy and very wet....schools likely to close...


after the rain we just got too...hear tell winds in the 50-60 range...that means the bridges all closed too...yay....home with a 6 year old, prob no power and too wet to play outside.....
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Evening All. Why does the NHC dissipate the low after 72 hrs? I am expecting some nasty weather from this storm in the northeast.
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21n 82.5?
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Quoting charlottefl:
The storm isn't falling apart. Convection wise it's looking kinda sloppy, but the actual structure of the storm has improved. The core continues to tighten up (slowly). It's just that the low pressure is so broad. It's impossible for it to consolidate quickly like a lot of Atlantic storms that we've been accustomed to seeing.


You know how this blog works

If there is not an eye by tonight, it will be RIP LOL
Member Since: March 10, 2010 Posts: 1 Comments: 7368
Hey Tigg!!!!!!!!!!! Breezy and very wet....schools likely to close...
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Quoting kimoskee:
Flood waters rising...

Link

Getting a whole lot of rain in Kingston also.
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The storm isn't falling apart. Convection wise it's looking kinda sloppy, but the actual structure of the storm has improved. The core continues to tighten up (slowly). It's just that the low pressure is so broad. It's impossible for it to consolidate quickly like a lot of Atlantic storms that we've been accustomed to seeing.
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Quoting Levi32:


Where did I ever say that lol.

It will be getting better organized and strengthening as it crosses Florida.


Sorry Levi. Did not read back. My bad
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Press....what's ur take on a chas hit thurs?
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if a center does reform just west of jamaica how will this effect the storms path?
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623. JLPR2
Quoting MiamiHurricanes09:
Tropical systems contain lighting as do normal afternoon thunderstorms.


True I remember I got a nasty thunderstorm from Earl.
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Quoting weatherman12345:
POLL TIME
WHAT WILL TD 16 BE AT THE FLORIDA LANDFALL
A. 35 MPH
B. 40 MPH
C. 45 MPH
D. 50 MPH
E. 55 MPH OR GREATER

B
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Quoting GoodOleBudSir:


so it will not hit FL?


Where did I ever say that lol.

It will be getting better organized and strengthening as it crosses Florida.
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Flood waters rising...

Link
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Quoting Levi32:


Yes it's better organized than 11am. It will continue organizing and becoming stronger until landfall in the Carolinas.


so it will not hit FL?
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Station FBIS1 - Folly Island, SC
September 28, 2010 5:00 pm EDT
Location: 32.685N 79.888W
Wind Direction: S (170°)
Wind Speed: 6.0 knots
Wind Gust: 7.0 knots
Atmospheric Pressure: 29.75 in (1007.3 mb)
Pressure Tendency: -0.04 in (-1.4 mb)
Air Temperature: 77.0°F (25.0°C)
Dew Point: 58.3°F (14.6°C)
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Quoting gordydunnot:
Also these storms in s. fl. today have lightening which I would assume comes from the frontal system, so things maybe interesting enough already.Lastly Atmo or any of you skilled Mets, how are the cape values and atmospheric spin for Fl. this evening tomorrow if you don't mind.
Tropical systems contain lighting as do normal afternoon thunderstorms.
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Quoting presslord:
Folly Beach, SC Link


PRESS!!!!!! how's it hangin?
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lots of wind and heavy rain right now in west palm beach, closed the shutter in the patio to avoid rain coming in
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Quoting Levi32:


Lol. I guess it has to be bombing out to be strengthening.


yup
Member Since: March 10, 2010 Posts: 1 Comments: 7368
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Quoting Hurricanes101:


I have heard from people on here that it is falling apart lol


Lol. I guess it has to be bombing out to be strengthening.
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Folly Beach, SC Link
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We're under 997mb now. 33042
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Quoting Levi32:
Vorticity gradually getting tighter and more circular.



I also notice ex-Lisa and ex-Julia are still out there, very tenacious storms and vorticity with 2 of the waves from Africa as well.
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got weather bug on my puter...don't follow it as a religeon but it does send alerts so that i can get on Wunderground and see what is up
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Quoting Levi32:


Yes it's better organized than 11am. It will continue organizing and becoming stronger until landfall in the Carolinas.


it is getting slightly tighter correct?
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Quoting Levi32:


Yes it's better organized than 11am. It will continue organizing and becoming stronger until landfall in the Carolinas.


I have heard from people on here that it is falling apart lol
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Quoting chrisdscane:


but tell me if u agree it has become better organized than ohh lets say 11am next question will it strenthen over night and lastly is it still organizing?


Yes it's better organized than 11am. It will continue organizing and becoming stronger until landfall in the Carolinas.
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Also these storms in s. fl. today have lightening which I would assume comes from the frontal system, so things maybe interesting enough already.Lastly Atmo or any of you skilled Mets, how are the cape values and atmospheric spin for Fl. this evening tomorrow if you don't mind.
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Vorticity gradually getting tighter and more circular.

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Currently my obs here in Merritt Island, FL:

Heavy Rain
Temp: 73F (22C)
Dewpoint: 72F (22C)
Humidity: 97%
Wind: NNE 13 Gusting to 26
Pressure: 29.69" Falling (1005mb)
Rainfall rate: 1.83"/hr
Total Precip today: 1.56"

I am located some 500 mi NNE of TD# 16. Thanks in part to three factors... a stalled cold front to my NW... east coast seabreeze developed... and increased moisture pooling ahead of TD# 16. Now I am trying to remember when was the last time it has been so cool in the afternoon (rain-caused obviously... since it was 90F at noon)
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Quoting Levi32:


Not SW of Jamaica. There is the possibility of a weak competing mid-level center near 18N, 83.5W, but the circulation in general is very broad. There is a massive dimple of low pressure in the NW Caribbean right now illustrating a ton of heat, but it is not bundled. It is very spread out right now and that's why this system would require a good chunk of time to become a very formidable storm.


but tell me if u agree it has become better organized than ohh lets say 11am next question will it strenthen over night and lastly is it still organizing?
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Quoting Stormchaser2007:
Surface obs

Click for a better view:

FULL SIZE
Photobucket



FULL IMAGE
Photobucket


center relocating to the south east.. I've seen a structure like this before, the center is probably going to spin down towards the lowest area of pressure.. around the broad circulation.. happens a lot before they really take off... it may end up being a lot stronger than expected if it does relocate.. and it's looking more and more likely with pressures that low to the south east of the "center".
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Quoting sammywammybamy:


Hey tigger, long time no see


hey sammy...been hectic here...my little one needs reconstructive ear surgery...doc every week, plus 2 jobs on top
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Not really concerned about the wind here in WPB.

All I really care about is that I have to get up at 5am and commute to Miami in the rain.
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Quoting Hurricanes101:
\

I think he means the first part of the track that takes the storm ashore in SW Florida


I say everglades, but with such a broad center that track may change if the center suddenly tightens in favor of one side of the circulation.
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Quoting victoriahurricane:


A tad? All the models have it landing west of the NHC and only 2 have it exiting florida to the east of NHC. I'm thinking there should be a pretty big shift at 11.
Maybe it is a shift of what? The large windless low pressure center?
NHCs main responsibility in predicting tracks is to protect the public so they show "landfall" bias towards the highest wind fields. They already say that reporting a center is moot in the 1700 discussion.
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GFS shifted back east, hence why the NHC did not buy the west shift
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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.