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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It looks like to me the lowest pressure is to the east of Cayman Islands, but its VERY spread out. The entire pass on the recon was all 999 mb.

Very sub-tropical indeed.
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Quoting StormChaser81:


This almost sounds like he's forcing us to listen.

Shouldn't it say Dr. Masters is going to be on Hurricane Haven, please come join us and feel free to ask questions.

The one above makes me not want to listen, just because he seems so forceful in his message.

Maybe it's the way you read it, which speaks volumes about you. I, personally didn't read anything forceful or demanding at all in the post.
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Quoting Patrap:
Convection has really waned the last 2 Hours with TD-16.

She may be feeling D-Min and giving up some convective bursts to organizing some.

Only time will tell.




true i agree with that before just to much going on ( as far as convection) for it to be organized it'll shrink and intensify tonight i think we all agrre on that
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131. shauntanner (Admin)
Listen to Dr. Masters on the Hurricane Haven here at 4 p.m. ET, 1 p.m. PT. Call in with questions at 415-983-2634 or write questions to broadcast@wunderground.com if you have anything that needs answering about the tropics.
Quoting CybrTeddy:
TD16 (I can't believe we are sitting here talking about TD16 in September, 2008 didn't get TD16 until November!) is very similar to Tropical Storm Barry in 2007, remember how there was a debate over whether it was sub-tropical or tropical, even though it was in the GOMEX in June?


I played golf the day Barry came through. He was very Bonnie-ish.
Member Since: August 14, 2008 Posts: 0 Comments: 553
Quoting StormChaser81:


This almost sounds like he's forcing us to listen.

Shouldn't it say Dr. Masters is going to be on Hurricane Haven, please come join us and feel free to ask questions.

The one above makes me not want to listen, just because he seems so forceful in his message.
Want some tissue?
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Ya know, Wundercaymankid may not be too far off, the center may be between those two convective clusters south of 20N around 82W.

If that's where the center is, then this storm is organizing well and should be a TS now.. That's IF this is where the center is. He did mention pressure was falling at a good rate as well.

Member Since: July 1, 2008 Posts: 13 Comments: 7436
You can try and pinpoint the center, but it's really BROAD. Stretches from the Caymans on the E to the s. tip of Cuba on the N, and almost to the W. tip of Cuba on the west side. Doesn't look like it's moved much at all to me over the last 7 or 8 hours. In the last 3 or 4 hours though it looks like it's trying to tighten up a little bit. It's a slow process with that broad a low pressure area.
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TD16 (I can't believe we are sitting here talking about TD16 in September, 2008 didn't get TD16 until November!) is very similar to Tropical Storm Barry in 2007, remember how there was a debate over whether it was sub-tropical or tropical, even though it was in the GOMEX in June?
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Quoting BLee2333:


Pressure is a lot lower NW of there.


actually pressures are lower here in cayman
Link
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122. shauntanner (Admin)
Listen to Dr. Masters on the Hurricane Haven here at 4 p.m. ET, 1 p.m. PT. Call in with questions at 415-983-2634 or write questions to broadcast@wunderground.com
Does anyone know if recon really has a fix on COC yet? They appear to spending alot of time around 19N 82W area.....
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Quoting FLHurricaneHunter:
Looking at recon coming in I am thinking center somewhere in 19.5N 82.1W area? anyone?


Pressure is a lot lower NW of there.
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Tampa will get some weather tonight as the warm front located over central Florida moves north and intensifies, but shouldn't get much of anything but a pleasant north breeze around 20 mph and a few wrap-around showers.
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Is it me or does it look like the front that came through last night is going back north now? Odd
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Quoting StormChaser81:


This almost sounds like he's forcing us to listen.

Shouldn't it say Dr. Masters is going to be on Hurricane Haven, please come join us and feel free to ask questions.

The one above makes me not want to listen, just because he seems so forceful in his message.


Forceful?
Seen a TV ad lately?
Seriously... Lighten up.
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Quoting 1900hurricane:


It would definitely be a rarity.

It is also rare to have a trough digging south of 25 degrees this early.
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Quoting smartinwx:


So, a LAKE WIND ADVISORY needs to be issued for Wednesday.
I know my NWS office stopped using the LAKE WIND and now only issues WIND. I do not know if this was a nationwide change for 2010 or just a change on an office by office basis.
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Quoting StormChaser81:


This almost sounds like he's forcing us to listen.

Shouldn't it say Dr. Masters is going to be on Hurricane Haven, please come join us and feel free to ask questions.

The one above makes me not want to listen, just because he seems so forceful in his message.


Ummm...what? Consider it an ad; they seldom say please. Besides, this is, after all, his blog. Oh, and his website, too...
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Winds picking up as they move into the SE quadrant.

From 242° at 29 knots
(From the WSW at ~ 33.3 mph)

Might already be TS.
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Quoting TampaFLUSA:
Any thoughts on the Tampa area anyone?


i enjoy living here. ;)
Member Since: August 14, 2008 Posts: 0 Comments: 553
Quoting K8eCane:
Dr Masters actually mentioned Wilmington NC which is where I live and yes we have been INUNDATED with rain
Yes...I think yall might be in for the worst of this system. Unless there is a significant change in the track.
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Looking at recon coming in I am thinking center somewhere in 19.5N 82.1W area? anyone?
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Quoting TampaFLUSA:
Any thoughts on the Tampa area anyone?


I love Tampa!!
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Quoting oceanblues32:
well if it already seems to be a tropical storm what are the chances of this stregthening tonite!!!


Very slow strengthening. 45 mph tops for Southern Florida. Probably a little higher for North and South Carolina.
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WOW, that cold front must be French!
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Quoting TampaFLUSA:
Any thoughts on the Tampa area anyone?


Depending on how far west it tracks, we could get some rain - nothing like the east coast will see.
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Quoting hydrus:
It looks sub-tropical..Which means if it does intensify, it should resemble a glorified tropical Nor,Easter or something. And shear will have little to do with its development.


Well I think the NHC and Dr. Masters would have mentioned it, if that was the case.

We dont get these type storms usually, so of course it's going to look different.
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A westward shift would mean more rain and wind for the east coast.
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If center fix is further south then I would be agreement we will see TS Nicole tonite...


Quoting CybrTeddy:


I think it will become TS Nicole tonight, peaking at 45 mph when it hits Florida.
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Convection has really waned the last 2 Hours with TD-16.

She may be feeling D-Min and giving up some convective bursts to organizing some.

Only time will tell.

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well if it already seems to be a tropical storm what are the chances of this stregthening tonite!!!
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Any thoughts on the Tampa area anyone?
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Quoting oceanblues32:
who thinks this can stregthen tonite?


I think it will become TS Nicole tonight, peaking at 45 mph when it hits Florida.
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I am starting to think recon is having issues with the surface wind data
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I don't recall having storms forming from monsoonal type weather patterns in the Atlantic.

Much more likely to occur in the Pacific.
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Pouring and squally down here in the Coral Gables.
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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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