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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Here comes October fest...
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Quoting Skyepony:
AF308 looks like it is about to take off.


Thanks for the heads-up Skye...Just brought up Google Earth tracking...

v/r

Jon
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1683. Skyepony (Mod)
Cosmic~ That's the Hurricane Hunters. Probably aiming for the first center fix to be a little before 06Z.
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Quoting foggymyst:
I am a teacher, just wondering if officials could be waiting for a the td to be name before cancelling schools. Wonder if anyone has asked a school bus driver about driving in a regular strong storm with children, how about kids that walk to and from school. IF you think this does not happen even in storms, think again. Parents that have limited reources check off "my child will walk home from school even in inclement weather" (i teach elementary).. The notion is just crazy.
The parents need to be involved. They should keep their kids home if they feel there is danger. I don't leave anything up to govt. God bless you BTW!
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Judging from the new COC, which I think is pretty much a done deal right now, we will be looking at a system that is more tropical than earlier predicted. That means a potentially deeper low, with not much change in steering, but with more speed up the East Coast.

This could be a New England storm.

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Cuban Radar Loop :O)
Member Since: August 25, 2009 Posts: 20 Comments: 6785
pressures are also droping here too earler was 998.5mbs now 998.2mbs and falling JLPR2
Member Since: June 13, 2009 Posts: 2 Comments: 11963
Quoting swflurker:
UPDATE...
LATEST SURFACE ANALYSIS CONTINUES TO SHOW FRONTAL TROUGH ACROSS
CNTRL FLORIDA WITH BROAD AREA OF LOW PRESSURE ASSOCIATED WITH
TROPICAL DEPRESSION 16 JUST SOUTH OF WESTERN CUBA. TROPICAL
DEPRESSION 16 CONTINUES TO BE NOT WELL ORGANIZED.
THE STRONGEST
WINDS ASSOCIATED WITH THE SYSTEM ARE WELL REMOVED FROM THE CENTER
TO THE EAST AND THIS MEANS GIVEN THE LATEST GUIDANCE WIND THREAT
AT THIS TIME CONTINUES TO BE MINIMAL. HOWEVER...GIVEN OUR LIMITED
SKILLS WITH FORECASTING CHANGES IN STRUCTURE ASSOCIATED WITH THESE
SYSTEMS, WE CANNOT STATE SOUTH FLORIDA IS OUT OF THE HOOK. THE
UNCERTAINTY CERTAINLY WARRANTS THE CONTINUATION OF THE WARNINGS
CURRENTLY IN PLACE.
Member Since: Posts: Comments:
1677. KEEPEROFTHEGATE (Mod)
Quoting GTcooliebai:

Hey I don't know if anybody ever asked this, but what does PGI stand for?
pouch guidance invest from the navy school
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Quoting GTcooliebai:

Nope, lol not tropical related, WE WON... I MEAN DA RAYS WON BABII!!! YEAH!!! & they clinch a playoff spot, so tomorrow everyone around the area, fans, bandwagon fans, fans who don't even go to the game, etc get the day off. And the president of the team has decided to give away free tickets to game tomorrow or you can just stay home & celebrate.

Yeah, like as if. Nice try. Tix will be given out at stadium beginning at 4:45pm for a 710 game. Perfect time to setup a sting with school resource officers and take all you youngens to Juvenile detention tomorrow.
By the way congrats to Rays!
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1675. pottery
Quoting sunlinepr:


Where is the Low centered? Adjusted to the east? If so, Will the projected path has to be adjusted???

If the thing settles down and begins to rotate around a center, the models will have to take notice of that.
So far, no rotation at the surface....
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UPDATE...
LATEST SURFACE ANALYSIS CONTINUES TO SHOW FRONTAL TROUGH ACROSS
CNTRL FLORIDA WITH BROAD AREA OF LOW PRESSURE ASSOCIATED WITH
TROPICAL DEPRESSION 16 JUST SOUTH OF WESTERN CUBA. TROPICAL
DEPRESSION 16 CONTINUES TO BE NOT WELL ORGANIZED. THE STRONGEST
WINDS ASSOCIATED WITH THE SYSTEM ARE WELL REMOVED FROM THE CENTER
TO THE EAST AND THIS MEANS GIVEN THE LATEST GUIDANCE WIND THREAT
AT THIS TIME CONTINUES TO BE MINIMAL. HOWEVER...GIVEN OUR LIMITED
SKILLS WITH FORECASTING CHANGES
IN STRUCTURE ASSOCIATED WITH THESE
SYSTEMS, WE CANNOT STATE SOUTH FLORIDA IS OUT OF THE HOOK. THE
UNCERTAINTY CERTAINLY WARRANTS THE CONTINUATION OF THE WARNINGS
CURRENTLY IN PLACE.
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Pressure at Grand Cayman airport dropped to 997, starting to rise again
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I am a teacher, just wondering if officials could be waiting for a the td to be name before cancelling schools. Wonder if anyone has asked a school bus driver about driving in a regular strong storm with children, how about kids that walk to and from school. IF you think this does not happen even in storms, think again. Parents that have limited reources check off "my child will walk home from school even in inclement weather" (i teach elementary).. The notion is just crazy.
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Quoting Skyepony:
AF308 looks like it is about to take off.
Is that one a HH or a G-IV. If it is a HH, when should we expect reports?
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Quoting IamTheCanesSurfer:
Wind Direction (WDIR): SE ( 130 deg true )
Wind Speed (WSPD): 27.2 kts
Wind Gust (GST): 31.1 kts
Wave Height (WVHT): 7.9 ft
Dominant Wave Period (DPD): 7 sec
Average Period (APD): 5.3 sec
Mean Wave Direction (MWD): ESE ( 107 deg true )
Atmospheric Pressure (PRES): 29.74 in
Pressure Tendency (PTDY): +0.05 in ( Rising )
Air Temperature (ATMP): 77.9 °F
Water Temperature (WTMP): 83.5 °F
Salinity (SAL): 35.38 psu
Dew Point (DEWP): 69.8 °F
Heat Index (HEAT): 80.1 °F
Which buoy is this ?
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1669. flsky
Major disaster declared for US Virgin Islands.
Link
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1668. Seastep
Quoting Skyepony:
AF308 looks like it is about to take off.


Thanks, skye. I thought they weren't going back until tomorrow.

Will be too late for me, but will check it in the AM.
Member Since: September 9, 2008 Posts: 6 Comments: 3414
1667. KEEPEROFTHEGATE (Mod)
a dominate centre of cirulation will win out first secondary then prime
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Quoting wunderkidcayman:
well looky what we have here

THERE ARE MULTIPLE LOW-LEVEL CLOUD SWIRLS PRESENT...AND THE CENTER
APPEARS TO RE-FORM FROM TIME TO TIME.

maybe the reall COC is reforming just to the SE of us
just now reading that...must have hit your head when the terrorizing winds knocked you out of your chair
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1665. pottery
Quoting Seastep:


LOL. I tell ya, I really need to make use of that preview button.

No Prob.
hehehehh
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Wind Direction (WDIR): SE ( 130 deg true )
Wind Speed (WSPD): 27.2 kts
Wind Gust (GST): 31.1 kts
Wave Height (WVHT): 7.9 ft
Dominant Wave Period (DPD): 7 sec
Average Period (APD): 5.3 sec
Mean Wave Direction (MWD): ESE ( 107 deg true )
Atmospheric Pressure (PRES): 29.74 in
Pressure Tendency (PTDY): +0.05 in ( Rising )
Air Temperature (ATMP): 77.9 °F
Water Temperature (WTMP): 83.5 °F
Salinity (SAL): 35.38 psu
Dew Point (DEWP): 69.8 °F
Heat Index (HEAT): 80.1 °F
Member Since: Posts: Comments:
well looky what we have here

THERE ARE MULTIPLE LOW-LEVEL CLOUD SWIRLS PRESENT...AND THE CENTER
APPEARS TO RE-FORM FROM TIME TO TIME.

maybe the reall COC is reforming just to the SE of us
Member Since: June 13, 2009 Posts: 2 Comments: 11963
1662. JLPR2
Winds are picking up in Jamaica with the pressure dropping too.

Link
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Quoting JLPR2:
PGI51L seems like the one with the control for the moment, it's the one with the 850mb vort.


Hey I don't know if anybody ever asked this, but what does PGI stand for?
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Where is the Low centered? Adjusted to the east? If so, Will the projected path has to be adjusted???
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1659. pottery
Quoting CaptnDan142:


With the proper inspiration, all things get better.

Absolutely>
cheers!
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1658. Seastep
Quoting pottery:

Er, that's rather personal, dont you think?
But just to cover for you, the weather here has been much drier the last 48 hrs.
Just some afternoon thunderstuff in and around the Mountains.
Drying out nicely.


LOL. I tell ya, I really need to make use of that preview button.
Member Since: September 9, 2008 Posts: 6 Comments: 3414
1657. Skyepony (Mod)
AF308 looks like it is about to take off.
Member Since: Posts: Comments:
1656. JLPR2
PGI51L seems like the one with the control for the moment, it's the one with the 850mb vort.

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1655. KEEPEROFTHEGATE (Mod)
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It looks like all that heavy lifting out there is finally paying off, just west of Jamaica.

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Quoting reedzone:
Anticyclone has formed over TD16, this should allow it to strengthen a bit into Nicole by morning.

and the reed model dooms the entire united states east of the Mississippi...please
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Quoting pottery:

LOL.
Glorious Inspiration.
I think I'll join you, and see what happens next...


With the proper inspiration, all things get better.
Member Since: August 21, 2007 Posts: 0 Comments: 856
Seems like the center has shifted east to the area of convection??? Is that correct???

Quoting Grothar:
The center is beginning to tighten up and wrap a little more convection. Don't look at the big blob, look at the center



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1649. Seastep
Wow. They did it again. It does look like one, but there is no data that I am aware of that would support STS. Must be because the winds do not support the pressure.

28/2345 UTC 22.3N 82.0W ST2.5 16L
Member Since: September 9, 2008 Posts: 6 Comments: 3414
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Quoting CaneWarning:


Hmmmm...

Don't even say cause I know what your thinking, :P
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Anticyclone has formed over TD16, this should allow it to strengthen a bit into Nicole by morning.

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Quoting Bielle:

Ahem???


The family hour, has different meaning's, apparently.
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Quoting OracleDeAtlantis:
It's pretty amazing when you look at all the buoy data coming in across the Caribbean. They're all showing declining pressure. Which means this thing is still winding up for the pitch.


I'm pretty sure that's how Hermine started. Miami and I watched as there was pressure drops all over the place.
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1642. pottery
Quoting Seastep:
Pottery - you still wet down there?

Er, that's rather personal, dont you think?
But just to cover for you, the weather here has been much drier the last 48 hrs.
Just some afternoon thunderstuff in and around the Mountains.
Drying out nicely.
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Quoting hunkerdown:
no, cause the kiddies don't want to go to school

Ya know what if ya think about it not since Fay have they cancel schools down there, right?
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About the only thing in the + column for 16L at the moment is that it should be splashing down right about DMAX. Could be why the GFDL is showing modest strengthening once N of Cuba.
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Looks like these waves will be consolidated as part of all that monsoonal energy, or even feed Nichole when it gets her name....

Quoting JLPR2:


CATL mess
I wonder where will this area consolidate at last?
Or maybe it wont even do that.
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Quoting Nateball:


For what? A little bit of rain.
no, cause the kiddies don't want to go to school
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1636. Seastep
Pottery - you still wet down there?
Member Since: September 9, 2008 Posts: 6 Comments: 3414
Quoting OracleDeAtlantis:
It's pretty amazing when you look at all the buoy data coming in across the Caribbean. They're all showing declining pressure. Which means this thing is still winding up for the pitch.


also look at wind directions at observation points shows a very broad circulation still in the area
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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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