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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GFS shifted back east, hence why the NHC did not buy the west shift
Member Since: March 10, 2010 Posts: 1 Comments: 7813
i live west ashley, just across the bridge from down town...the last couple days of rain were bad here...no where for water to go...my back yard is already in my front yard now....
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lawlz.. its 124 degrees in the middle of the gulf of mexico...

http://www.ssd.noaa.gov/goes/east/gmex/loop-wv.html

Member Since: April 17, 2010 Posts: 0 Comments: 1753
1004 mb pressure, west palm....school tomorrow(university) so far...
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just looked at the last visiable loop today and it seems as if the center is on the move and making landfall in cuba just n of the is. of juventude
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Quoting nash28:
Ok guys GOT IT!!!!

Misread. Busy doing five hundred things at home right now.

Still they went against the model guidance. Very odd of the NHC to do that.


They purposely have a delayed reaction to major model shifts.
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Last forecast till we have a center with convection on all sides. All most every model and good met. on this blog has been predicting numerous low's generating in the western Caribbean.I think we are seeing that unfold now, when trof lifts significantly out of the way that's when the game for this season is on so to speak.IMO Till then we get little tastes of things possibly to come.
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Marathon, 29.53 in (Falling).
Key West, 29.59 in (Falling).
Member Since: August 18, 2008 Posts: 0 Comments: 681
Surface obs

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Quoting Levi32:


A track near Cape Canaveral makes sense. The clouds are pointing the way where the storm will go as we speak. You can see where pressures are starting to fall the most over Florida as the trough digs in by looking at the area of maximum upper divergence. The storm will simply ride the corridor of low pressure northward. Fortunately for Florida, the same corridor of low pressure is also what will keep this from blowing up into a monster.
\

I think he means the first part of the track that takes the storm ashore in SW Florida
Member Since: March 10, 2010 Posts: 1 Comments: 7813
572. bwi
Weird to see pressures simultaneously falling by 0.5-1mb per hour across such a wide area.
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Quoting zoomiami:
The problem with a system like this is it could turn like Bonnie, which was really the same as our afternoon thunderstorms, or it could be a mess like Katrina or Irene. Both of these last storms brought much more weather than anyone expected.

Seems to me they are assuming that it won't be much weather. If that changes, there are going to be a lot of people on the road, and it will be a real mess.


Bingo! That is the way I feel.. I do not want to over react because of storms like Bonnie and remember that one in 2006 that never developed and we were all boarded up and let kids out of school.. it never even rained!

but then Irene was suppose to be not much of anything and it fooded us for days....

Katrina was not suppose to hit South Florida as bad as it did...




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torn here...if it hits the charleston, sc area which is very possible, they will close the coastal schools...if they do that, i will be off work and home with a 6 year old with poss of no power cuz it goes out with normal rains here...hmmmmm.....home with 6 year old or to work with monsoon rains....decisions decisions
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Quoting weatherman12345:

do you agree with the GFS right now on the track Levi.. leaving out the pressure


A track near Cape Canaveral makes sense. The clouds are pointing the way where the storm will go as we speak. You can see where pressures are starting to fall the most over Florida as the trough digs in by looking at the area of maximum upper divergence. The storm will simply ride the corridor of low pressure northward. Fortunately for Florida, the same corridor of low pressure is also what will keep this from blowing up into a monster.
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Ok guys GOT IT!!!!

Misread. Busy doing five hundred things at home right now.

Still they went against the model guidance. Very odd of the NHC to do that.
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567. skook
-
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Quoting Stormchaser2007:


LOL

It was a joke.


Ah ok, I always found it funny when I would plot storms and I would miss a minus in the latitude or longitude and it would put the forecast point on the other side of the globe with a really long line lol
Member Since: March 10, 2010 Posts: 1 Comments: 7813
Quoting RotorYacht:
Great..

LOL we already have them; everyone just ignores them when we have plent of water in our canals and water tables!
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Lower Keys 997.2 Millibars. 29.45 in (Falling) Zip 33042.
Member Since: August 18, 2008 Posts: 0 Comments: 681
Quoting Hurricanes101:


its just a feed back issue where the storm plot is connected back to the original position

has no bearing on the validity of the forecast model run at all


LOL

It was a joke.
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Quoting nash28:


The center moved west. They adjusted the track east.. I'm lost.. The models moved a pretty good clip west and they went with the UKMET and ECMWF. May change at 11pm.
Read that again. They adjusted it to the west but it lies east of the current model guidance.
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Quoting WeatherNerdPR:
Good Afternoon. I see we have 016L (isn't the prettiest rose in the bunch). Funny it hasn't been for 12 hours and already has a Wiki Page lol.


Yeah, when there is a storm threatening land, or when there are warnings up, we make an article for it.
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now 997.5mb
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Preasure is 1005 in Ruskin Fl. Falling for 14 hours
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Quoting Levi32:
That is a problem is the GFS initializing the pressure field a good 5mb too high in the NW Caribbean.



No the GFS has it correct, just showing the surrounding isobar is at 1000 but inside it, 997mb-999mbs :)
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Quoting nash28:


The center moved west. They adjusted the track east.. I'm lost.. The models moved a pretty good clip west and they went with the UKMET and ECMWF. May change at 11pm.


they did not adjust the track east

again the 11am track was on the East coast of Florida, the 5pm has the system coming over SE Florida to the west of Miami
Member Since: March 10, 2010 Posts: 1 Comments: 7813
Quoting weatherboyfsu:
BASED ON A BLEND OF THE AIRCRAFT...SURFACE...AND SATELLITE DATA THE
CENTER HAS BEEN RELOCATED SLIGHTLY TO THE WEST OF THE PREVIOUS
TRACK.
NO SIGNIFICANT MODIFICATIONS HAVE BEEN MADE TO THE TRACK
FORECAST OR SYNOPTIC REASONING. A CONTINUED NORTH-NORTHEASTWARD
MOTION WITH ACCELERATION...BETWEEN THE AFOREMENTIONED TROUGH AND A
MID-LEVEL ANTICYCLONE OVER THE WESTERN ATLANTIC...IS EXPECTED UNTIL
THE SYSTEM DISSIPATES. THE TRACK FORECAST IS NOW A LITTLE TO THE
EAST OF THE MODEL CONSENSUS BUT QUITE CLOSE TO THE NEW U.K. MET.
OFFICE AND ECMWF GLOBAL MODEL TRACKS

Nash,

He said that it was moved to the west.... Im lost


The center moved west. They adjusted the track east.. I'm lost.. The models moved a pretty good clip west and they went with the UKMET and ECMWF. May change at 11pm.
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Quoting Stormchaser2007:
I'll have what the GFS is having.


Are they crazy?!
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Quoting nash28:
Still a little stymied as to how the NHC shifted the track further east on the 5pm as opposed to west.....

UKMET?? Need I say any more? They can't ignore the 18z..

***
The 18z now just starting it's run now so let' see and, . . . I suppose the NHC can ignore whatever they please.
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Quoting sammywammybamy:
Expect a Tad Shift Left at 11pm.



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.
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Quoting Stormchaser2007:
I'll have what the GFS is having.



its just a feed back issue where the storm plot is connected back to the original position

has no bearing on the validity of the forecast model run at all
Member Since: March 10, 2010 Posts: 1 Comments: 7813
I think the center may be reforming to the s east where the heaviest convection is. Very common with these monsoon systems
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Preasure in uskin Fl is 1005 been falling for 14 hours
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That is a problem is the GFS initializing the pressure field a good 5mb too high in the NW Caribbean.

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Good Afternoon. I see we have 016L (isn't the prettiest rose in the bunch). Funny it hasn't been for 12 hours and already has a Wiki Page lol.
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Quoting largeeyes:
Gotta go get plywood. I'm in the sammywammy cone!

LOL!!!
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I'll have what the GFS is having.

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Quoting futuremet:
I don't expect Nicole to look any better than this when it is over Florida.



LOL, is that a 200nm eye forming in 474??
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BASED ON A BLEND OF THE AIRCRAFT...SURFACE...AND SATELLITE DATA THE
CENTER HAS BEEN RELOCATED SLIGHTLY TO THE WEST OF THE PREVIOUS
TRACK.
NO SIGNIFICANT MODIFICATIONS HAVE BEEN MADE TO THE TRACK
FORECAST OR SYNOPTIC REASONING. A CONTINUED NORTH-NORTHEASTWARD
MOTION WITH ACCELERATION...BETWEEN THE AFOREMENTIONED TROUGH AND A
MID-LEVEL ANTICYCLONE OVER THE WESTERN ATLANTIC...IS EXPECTED UNTIL
THE SYSTEM DISSIPATES. THE TRACK FORECAST IS NOW A LITTLE TO THE
EAST OF THE MODEL CONSENSUS BUT QUITE CLOSE TO THE NEW U.K. MET.
OFFICE AND ECMWF GLOBAL MODEL TRACKS

Nash,

He said that it was moved to the west.... Im lost
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Maybe because the center is relocating SW of Jamaica?

Quoting nash28:
Still a little stymied as to how the NHC shifted the track further east on the 5pm as opposed to west.....

UKMET?? Need I say any more? They can't ignore the 18z..
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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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