Dr. Jeff Masters' WunderBlog

TD 16 organizing; Mexican landslide kills hundreds; hottest day ever in Los Angeles

Posted by: Dr. Jeff Masters, 7:25 PM GMT on September 28, 2010

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.

Categories: Hurricane

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201. gordydunnot 8:27 PM GMT on September 28, 2010
You can listen to the Doc and blog at same time open a second window. Lastly we are getting some pretty interesting squalls in ne dade right now should get everyone's attention. Member Since: August 18, 2008 Posts: 0 Comments: 3044

202. xCat6Hurricane 8:27 PM GMT on September 28, 2010
Quoting RobbWilder: 35 - 40 miles an hour and its not safe to run the busses for them. They close. They want to make sure the system doesnt fizzle first. They will have to do it by 6 I would think to make the evening news cycle. (they are antiquated after all) They don't have to do anything by 6, Or have anything to do with evening news. They will advertise it on local channels down at the bottom of the screen in the AM. Member Since: July 19, 2010 Posts: 0 Comments: 111

203. newportrinative 8:28 PM GMT on September 28, 2010
Quoting chrisdscane: didnt channel 7 just syas public schools r closed? Nope....from Channel 7 website: - Broward County Public Schools will be open. (Situation will be re-evaluated at 4:30 p.m. Tuesday) Member Since: May 20, 2009 Posts: 0 Comments: 203

205. Katelynn 8:28 PM GMT on September 28, 2010
Quoting FLHurricaneHunter: nice radar of florida with projected path overlayed... it will shift as official storm path from NHC shifts, if any. Link Thanks for posting that one! Member Since: August 27, 2010 Posts: 0 Comments: 70

206. TreasureCoastFl 8:29 PM GMT on September 28, 2010
Quoting Hurricanes101: yea I am convinced the recon is having some issues with the surface wind observations onboard, most of the surface winds they have shown are questionable local weatherman says they are havng difficulty finding anything that resembles tropical storm force winds. Are you my local weatherman? lol Member Since: August 18, 2008 Posts: 0 Comments: 444

207. unf97 8:29 PM GMT on September 28, 2010
I am waiting on the next set of model runs later this evening to see if the trend to back the track to the left(west) continues. If it does, like I stated yesterday, any shift of the track left would make a considerable difference in terms of impacts in regards to rainfall over the peninsula. Member Since: September 25, 2007 Posts: 0 Comments: 1193

208. Dakster 8:30 PM GMT on September 28, 2010
Quoting kwgirl: You can call MCSheriff's office to find out. But as long as I have been living here, no one official closes the bridges. They have advisories telling you any high profile vehicles may have a steering problem especially on the approaches. With this storm, unless it is a school bus, or some other type of high profile vehicle, you should have no problem. Just squally weather. I thought they locked the bridges DOWN, preventing you from moving a large boat by water. (as opposed to towing it with a vehicle). Member Since: March 10, 2006 Posts: 0 Comments: 4938

209. sporteguy03 8:30 PM GMT on September 28, 2010
Quoting Hurricanes101: a lot did That puts more of the I-4 corridor into play. Member Since: July 7, 2005 Posts: 0 Comments: 4824

211. Fotograffa 8:30 PM GMT on September 28, 2010
Quoting So far in NJ I've had about 2 inches. Yet we are still as much as a foot below normal over the past 90 days. So we need it badly up here. Where abouts in NJ? Right now I'm near AC and it's been very dry here. I'm hoping we can get a little rain from these systems to bring us up to whatever normal is. Member Since: June 6, 2005 Posts: 0 Comments: 50

212. sunlinepr 8:30 PM GMT on September 28, 2010
Seems like october comes with surprises... Member Since: August 2, 2010 Posts: 19 Comments: 8447

213. Clearwater1 8:30 PM GMT on September 28, 2010
Quoting unf97: I am waiting on the next set of model runs later this evening to see if the trend to back the track to the left(west) continues. If it does, like I stated yesterday, any shift of the track left would make a considerable difference in terms of impacts in regards to rainfall over the peninsula. yes indeed. And a significance shift left may mean more intensity. Member Since: August 26, 2006 Posts: 0 Comments: 1502

215. Hurricanes101 8:30 PM GMT on September 28, 2010
Quoting TreasureCoastFl: local weatherman says they are havng difficulty finding anything that resembles tropical storm force winds. Are you my local weatherman? lol Not sure what that means, but I am going by the fact that about 90% of the surface wind obs that have been transferred have a red asterisk next to them; meaning they are questionable Never seen them have so many questionable obs, tells me something is wrong Member Since: March 10, 2010 Posts: 1 Comments: 6902

216. gijim 8:30 PM GMT on September 28, 2010
Anyone want to put odds on a hurricane hitting FL? I'd give it 40%, 60% strong TS. TCHP is still pretty gnarly, provided circulation condenses around the COC tonight, I think it's quite possible. Yet everyone is still saying 30mph storm. Member Since: August 27, 2006 Posts: 0 Comments: 19

218. lickitysplit 8:32 PM GMT on September 28, 2010
Amazing how chill and smart the comment section is now that I've got everyone on "ignore". Should have done that 5 years ago. Member Since: May 17, 2007 Posts: 0 Comments: 621

219. gordydunnot 8:32 PM GMT on September 28, 2010
Doc implied if you think this week is fun stay tuned to next week. Member Since: August 18, 2008 Posts: 0 Comments: 3044

220. xCat6Hurricane 8:32 PM GMT on September 28, 2010
Quoting gijim: Anyone want to put odds on a hurricane hitting FL? I'd give it 40%, 60% strong TS. TCHP is still pretty gnarly, provided circulation condenses around the COC tonight, I think it's quite possible. Yet everyone is still saying 30mph storm. I'd say the carolinas have a better chance of seeing a hurricane Member Since: July 19, 2010 Posts: 0 Comments: 111

221. Patrap 8:32 PM GMT on September 28, 2010
Atlantic Ocean View (Updated ~3 hours) Member Since: July 3, 2005 Posts: 371 Comments: 111503

222. Thaale 8:32 PM GMT on September 28, 2010
Dr. Masters just said on Hurricane Haven that there's a 30% to 40% chance that 96L never makes it to Tropical Storm status! Member Since: October 19, 2005 Posts: 0 Comments: 308

223. TreasureCoastFl 8:33 PM GMT on September 28, 2010
Quoting Hurricanes101: Not sure what that means, but I am going by the fact that about 90% of the surface wind obs that have been transferred have a red asterisk next to them; meaning they are questionable Never seen them have so many questionable obs, tells me something is wrong just thought it was funny that you both seemed ot be saying the same thing. That's all he said so far: "Hurricane Hunter having a difficult time finding anything that resembles a tropical storm force wind in TD16" Member Since: August 18, 2008 Posts: 0 Comments: 444

226. docrod 8:33 PM GMT on September 28, 2010
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). Thanks all; I had meant vehicular traffic; of course trailers and high profile are another matter. Member Since: April 21, 2006 Posts: 0 Comments: 605

227. Seflhurricane 8:34 PM GMT on September 28, 2010
Quoting Thaale: Dr. Masters just said on Hurricane Haven that there's a 30% to 40% chance that 96L never makes it to Tropical Storm status! it is just about at TS status , it will be upgraded at 5Pm what are you hearing !!!!! Member Since: July 14, 2009 Posts: 0 Comments: 2898

229. Hurricanes101 8:34 PM GMT on September 28, 2010
Quoting TreasureCoastFl: just thought it was funny that you both seemed ot be saying the same thing. That's all he said so far: "Hurricane Hunter having a difficult time finding anything that resembles a tropical storm force wind in TD16" 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 Member Since: March 10, 2010 Posts: 1 Comments: 6902

230. CybrTeddy 8:34 PM GMT on September 28, 2010
Quoting gijim: Anyone want to put odds on a hurricane hitting FL? I'd give it 40%, 60% strong TS. TCHP is still pretty gnarly, provided circulation condenses around the COC tonight, I think it's quite possible. Yet everyone is still saying 30mph storm. 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. Member Since: July 8, 2005 Posts: 253 Comments: 20251

231. chrisdscane 8:35 PM GMT on September 28, 2010
it still remains disorganized

232. Seflhurricane 8:35 PM GMT on September 28, 2010
Quoting Hurricanes101: Not sure what that means, but I am going by the fact that about 90% of the surface wind obs that have been transferred have a red asterisk next to them; meaning they are questionable Never seen them have so many questionable obs, tells me something is wrong how strong are the winds that recon is finding Member Since: July 14, 2009 Posts: 0 Comments: 2898

234. Hurricanes101 8:35 PM GMT on September 28, 2010
they now have the surface wind observations off again Member Since: March 10, 2010 Posts: 1 Comments: 6902

235. unf97 8:36 PM GMT on September 28, 2010
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. Member Since: September 25, 2007 Posts: 0 Comments: 1193

238. xCat6Hurricane 8:36 PM GMT on September 28, 2010
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 Member Since: July 19, 2010 Posts: 0 Comments: 111

239. Neapolitan 8:36 PM GMT on September 28, 2010
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... ;-) Member Since: November 8, 2009 Posts: 4 Comments: 11159

240. Grothar 8:36 PM GMT on September 28, 2010
Anybody in the Ft. Lauderdale area notice there are no birds around? Member Since: July 17, 2009 Posts: 56 Comments: 19544

241. TOMSEFLA 8:36 PM GMT on September 28, 2010
recon never sent a vortex report????

242. StormChaser81 8:37 PM GMT on September 28, 2010
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. Member Since: August 11, 2008 Posts: 0 Comments: 2315

243. BobinTampa 8:37 PM GMT on September 28, 2010
Quoting yacoub: Was it a spelling bee? Ok, now THAT'S funny!! +1 Member Since: August 14, 2008 Posts: 0 Comments: 508

245. Patrap 8:38 PM GMT on September 28, 2010
San Fran Hotter than NOLA right now.. San Fran 94F, Nola 79F Member Since: July 3, 2005 Posts: 371 Comments: 111503

246. leo305 8:38 PM GMT on September 28, 2010
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.. Member Since: April 17, 2010 Posts: 0 Comments: 1752

247. FSUCOOPman 8:38 PM GMT on September 28, 2010
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. Member Since: August 29, 2008 Posts: 0 Comments: 332

248. newportrinative 8:38 PM GMT on September 28, 2010
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. Member Since: May 20, 2009 Posts: 0 Comments: 203

249. Thaale 8:39 PM GMT on September 28, 2010
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. Member Since: October 19, 2005 Posts: 0 Comments: 308

251. TreasureCoastFl 8:39 PM GMT on September 28, 2010
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. Member Since: August 18, 2008 Posts: 0 Comments: 444

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