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.

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351. RiverSteve 9:00 PM GMT on September 28, 2010
Quoting KanKunKid: So what's it like to sit at the adults table? Nothin' but love? I don't know when you last sat at "The adults table" at Thanksgiving, but it wasn't an exchange of info, learning about weather or the like was it? I always thought the kids had more fun and didn't have to listen to the relatives who liked to hear themselves talk. The only thing I learned was not helpful in the real world. I'm not sticking up for the troll, and I'm not picking on you. But is it possible to have fun AND learn about weather? +10 Member Since: August 14, 2009 Posts: 0 Comments: 54

352. robert88 9:00 PM GMT on September 28, 2010
Outerbanks are going to get the worst of this mess. Member Since: May 22, 2010 Posts: 0 Comments: 877

353. FSUCOOPman 9:00 PM GMT on September 28, 2010
New cone didn't shift west barely at all... about a hair. It got more narrow in the long-term. Link Member Since: August 29, 2008 Posts: 0 Comments: 331

354. seflagamma 9:00 PM GMT on September 28, 2010
Local News official words is Public Schools are set as of now to be Open tomorrow. and we have Flood Watch, and TS Warnings. still a TD not a TS yet. this is not going to be a big event for us I do not think... Member Since: August 29, 2005 Posts: 286 Comments: 40483

356. AllStar17 9:01 PM GMT on September 28, 2010
I really think the center may try to reform SW of Jamaica. Winds stronger and convection continues to flare up. Member Since: June 29, 2009 Posts: 13 Comments: 5135

357. Patrap 9:01 PM GMT on September 28, 2010
Member Since: July 3, 2005 Posts: 370 Comments: 111244

358. hydrus 9:01 PM GMT on September 28, 2010
Quoting MarathonZiggy: After reading the 5PM discussion, I'll stand on my earlier reasoning that the trough will preclude this TC from amounting to anything but a rain maker for the Bahama's & a little windier for S Fla in the near future. �Post Tropical is a whole different story though. Wow...is this a trough over the Eastern United States??.......:) Member Since: September 27, 2007 Posts: 1 Comments: 14248

360. seflagamma 9:02 PM GMT on September 28, 2010
They are saying if this storm does not "tighten up" most of the wind and even heavy rain will be far east of us here in South Florida. Member Since: August 29, 2005 Posts: 286 Comments: 40483

361. Patrap 9:02 PM GMT on September 28, 2010
Member Since: July 3, 2005 Posts: 370 Comments: 111244

362. clwstmchasr 9:02 PM GMT on September 28, 2010
Quoting kmanislander: I find it somewhat amusing that the surface pressure at Grand Cayman is lower than the pressure where the center of TD16 is. Doesn't make a lot of sense to me. Really shows that this is not a typical cyclone that we are use to seeing in our part of the world. Member Since: July 29, 2006 Posts: 0 Comments: 2754

364. Patrap 9:02 PM GMT on September 28, 2010
Member Since: July 3, 2005 Posts: 370 Comments: 111244

366. CosmicEvents 9:03 PM GMT on September 28, 2010
Quoting kmanislander: I find it somewhat amusing that the surface pressure at Grand Cayman is lower than the pressure where the center of TD16 is. Doesn't make a lot of sense to me. Doesn't seem to make sense. Perhaps it's indicative of just how broad the low pressure area is. And deep as well. Member Since: August 3, 2005 Posts: 10 Comments: 5097

368. leo305 9:03 PM GMT on September 28, 2010
david brenard just said.. its more likely that NICOLE moves east of SOUTH FLORIDA and that the heaviest weather will be well off shore.. ... I guess he ignored the models which is shocking for him.. based on what I've seen from him.. Member Since: April 17, 2010 Posts: 0 Comments: 1752

369. Patrap 9:03 PM GMT on September 28, 2010
Atlantic 26C Thermocline Member Since: July 3, 2005 Posts: 370 Comments: 111244

370. victoriahurricane 9:03 PM GMT on September 28, 2010
WHOA! 20:56:30Z 17.967N 79.117W 977.9 mb (~ 28.88 inHg) 204 meters (~ 669 feet) 1001.5 mb (~ 29.57 inHg) - From 224° at 21 knots (From the SW at ~ 24.1 mph) 19.1°C* (~ 66.4°F) - 26 knots (~ 29.9 mph) 55 knots (~ 63.2 mph) 33 mm/hr (~ 1.30 in/hr) 44.4 knots (~ 51.1 mph) Tropical Storm 211.5% Member Since: October 16, 2008 Posts: 0 Comments: 544

372. kmanislander 9:03 PM GMT on September 28, 2010
Quoting clwstmchasr: Really shows that this is not a typical cyclone that we are use to seeing in our part of the world. Conditions at our international airport Member Since: August 19, 2006 Posts: 0 Comments: 14939

373. gordydunnot 9:03 PM GMT on September 28, 2010
Cancel comment 338. But i still think there is more than one center but they had to make a choice, they got the plane, the plane, boss. Member Since: August 18, 2008 Posts: 0 Comments: 3044

374. GoWVU 9:04 PM GMT on September 28, 2010
Ok folks what does it look like for us here in Charleston SC? Member Since: September 12, 2007 Posts: 3 Comments: 349

376. leo305 9:05 PM GMT on September 28, 2010
Quoting seflagamma: They are saying if this storm does not "tighten up" most of the wind and even heavy rain will be far east of us here in South Florida. who's they? Member Since: April 17, 2010 Posts: 0 Comments: 1752

377. victoriahurricane 9:05 PM GMT on September 28, 2010
Quoting Patrap: Starting to refire some red cloud tops in the last frame and also finally some light blue pops north of the circulation. Member Since: October 16, 2008 Posts: 0 Comments: 544

378. AstroHurricane001 9:05 PM GMT on September 28, 2010
Looking at the GFS 12z run, we may get our W-named storm by mid-to-late October, and our first lake-effect snowfalls in S. Ontario by October 3 and Oct. 13. Member Since: August 30, 2008 Posts: 8 Comments: 2811

379. Patrap 9:05 PM GMT on September 28, 2010
638 fxus62 kchs 282035 afdchs Area forecast discussion National Weather Service Charleston SC 435 PM EDT Tuesday Sep 28 2010 Synopsis... a stationary front over the Atlantic will shift west closer to the coast tonight. A complex low pressure system will move up the southeast United States coast through Thursday. High pressure will build in from the northwest late in the week and over the weekend. && Near term /until 6 am Wednesday morning/... a strong shortwave will continue to drop southeast into the Tennessee Valley tonight and become cut off from the rest of the flow. Meanwhile...along the lingering stationary front offshore...an inverted surface trough of low pressure will develop. Moisture will continue to increase from east to west overnight along with isentropic ascent. The forecast area will also become situated in a favorable region for ascent of a strengthening upper level jet. Showers/isolated thunderstorms will become likely after midnight along the coast...spreading farther inland toward Interstate 95 toward daybreak. Lows will be coolest /around 60/ across far interior areas from Allendale southwest toward Millen while remaining in the lower to middle 70s along the coast. && Short term /6 am Wednesday morning through Friday/... a deepening cutoff low over the lower MS valley and strong upper level jet divergence over the eastern United States will increase frontogenesis along the SC/Georgia coasts on Wednesday. An impressive southerly flow will be in place through the entire troposphere by noon Wednesday with model forecast precipitable water/S increasing to an unseasonable 2.25" across southern SC. Tropical depression 16 is expected to become extratropical and merge with the baroclinic zone along the coast Wednesday night. The exact track of the coastal low will have a large impact on the band of heaviest rainfall. The 12z Gem and GFS both seemed fairly reasonable with their track of the coastal low in relation to the Upper Cutoff but seemed fast. Fortunately the 12z European model (ecmwf) came in with a very similar track to the aforementioned models but with a slower speed. We have a period of categorical probability of precipitation across the eastern half of the area Wednesday through Wednesday evening with likely probability of precipitation late Wednesday night in the eastern areas. The forecast for the western half of our area is more tricky because some guidance shows almost no precipitation while others show scattered to numerous showers. We have some rain chances in even farthest western zones but have a sharp pop gradient across the SC/Georgia border. Confined the thunderstorm possibilities to coastal waters and immediate coastal zones for most of the period where guidance indicates the negative lifted indices and some surface based instability. See the hydrology section for information on the Flash Flood Watch. Precipitation should be tapering off Thursday morning with partial clearing by afternoon. Temperatures will be close to normal. Member Since: July 3, 2005 Posts: 370 Comments: 111244

380. ecflweatherfan 9:05 PM GMT on September 28, 2010
Quoting cat5hurricane: Yep...I noticed that. And the Quantitative Precipitation Forecasts only are a general estimate. I would not be a bit surprised if locally some spots pick up much more than that. In fact there are areas here in Brevard County, FL that have received 6" of rainfall... and the bulk of the activity has not even arrived Member Since: March 19, 2010 Posts: 0 Comments: 947

381. Hurricanes12 9:05 PM GMT on September 28, 2010
Quoting leo305: who is they? Phil Ferro. Member Since: June 21, 2010 Posts: 0 Comments: 528

383. RobbWilder 9:05 PM GMT on September 28, 2010
Quoting sammywammybamy: South Florida Water Distirct Opening Flood Gates. Crap that means it wont rain. IF it does they will continue to drain the water again until we are in a CRISIS situation! Member Since: August 3, 2006 Posts: 0 Comments: 154

384. seflagamma 9:05 PM GMT on September 28, 2010
Also our local Water Management for SE Florida says they have been drawing down water in our canals for 24 hours now.. I did notice while I was out this afternoon that the water level had dropped some from yesterday in the canals... so at least we will have some room for some of the flooding. Member Since: August 29, 2005 Posts: 286 Comments: 40483

385. Hurricanes101 9:05 PM GMT on September 28, 2010
Recon found winds of 51mph Member Since: March 10, 2010 Posts: 1 Comments: 6902

386. Seastep 9:06 PM GMT on September 28, 2010
Quoting kmanislander: I find it somewhat amusing that the surface pressure at Grand Cayman is lower than the pressure where the center of TD16 is. Doesn't make a lot of sense to me. We don't know that, kman. The lowest reading was an hour and a half ago. You were about the same pressure, iirc. Let's see where it is when they get back in that area. Member Since: September 9, 2008 Posts: 6 Comments: 3406

388. clwstmchasr 9:06 PM GMT on September 28, 2010
Quoting seflagamma: Local News official words is Public Schools are set as of now to be Open tomorrow. and we have Flood Watch, and TS Warnings. still a TD not a TS yet. this is not going to be a big event for us I do not think... I am one that would rather be safe than sorry. But not in this case. With the NHC forecasting max winds of 45mph (SE of the center) the winds in FL should only be 25-30 mph. No reason to close schools. Member Since: July 29, 2006 Posts: 0 Comments: 2754

389. RadarRich 9:06 PM GMT on September 28, 2010
Wow, talk about amazing Lat/Longitude predictions. I went to this site, http://itouchmap.com/latlong.html (great site by the way, pretty cool stuff) Typed in my address in Boynton Beach, FL., and the points showed for my address: 26.50N/80.06W The 11AM 24 hour forcast position for TD16 showed: 26.5N/80.00W That's amazingly close to my rooftop. On top of it actually. Hopefully will not be too strong of a storm tomorrow evening, we shall see. Looks like a lot of rain, and not a big wind event.. Member Since: June 28, 2007 Posts: 0 Comments: 406

391. srada 9:06 PM GMT on September 28, 2010
Quoting Patrap: Second landfall right at Wilmington.. Member Since: August 17, 2006 Posts: 1 Comments: 772

393. CyclonicVoyage 9:07 PM GMT on September 28, 2010
Member Since: January 30, 2010 Posts: 0 Comments: 3259

394. seflagamma 9:07 PM GMT on September 28, 2010
Quoting weatherman12345: any news on the schools yet? Yes, Dade and Broward as of 5pm are scheduled to stay open. Quoting leo305: who's they? Chanel 7 new/Met... forgot his name.. Member Since: August 29, 2005 Posts: 286 Comments: 40483

395. WPBHurricane05 9:07 PM GMT on September 28, 2010
Quoting leo305: david brenard just said.. its more likely that NICOLE moves east of SOUTH FLORIDA and that the heaviest weather will be well off shore.. ... I guess he ignored the models which is shocking for him.. based on what I've seen from him.. Maybe he meant most of the weather from Nicole is offshore. Mike Lyons in WPB noted that the models shifted west which would give us more rain while Steve Weagel didn't seem that concerned minus the potential flooding. Member Since: July 31, 2006 Posts: 55 Comments: 7897

396. Hurricanes101 9:07 PM GMT on September 28, 2010
Quoting weatherman12345: was it near the coc no, south and east of it Member Since: March 10, 2010 Posts: 1 Comments: 6902

398. GoWVU 9:08 PM GMT on September 28, 2010
Quoting cat5hurricane: Not any good news I can give you thus far. Market street is sure gonna be in jeopardy if these precipitation forecasts are anywhere near accurate. How much in rain totals? What about winds? Member Since: September 12, 2007 Posts: 3 Comments: 349

399. victoriahurricane 9:08 PM GMT on September 28, 2010
Wow... 20:56:30Z 17.967N 79.117W 977.9 mb (~ 28.88 inHg) 204 meters (~ 669 feet) 1001.5 mb (~ 29.57 inHg) - From 224° at 21 knots (From the SW at ~ 24.1 mph) 19.1°C* (~ 66.4°F) - 26 knots (~ 29.9 mph) 55 knots (~ 63.2 mph) 33 mm/hr (~ 1.30 in/hr) 44.4 knots (~ 51.1 mph) Tropical Storm 211.5% Member Since: October 16, 2008 Posts: 0 Comments: 544

400. jjjerry1 9:08 PM GMT on September 28, 2010
when is someone going to tell me to run for my life Member Since: September 4, 2007 Posts: 0 Comments: 6

401. MarathonZiggy 9:08 PM GMT on September 28, 2010
Quoting ecflweatherfan: In fact there are areas here in Brevard County, FL that have received 6" of rainfall... and the bulk of the activity has not even arrived All due to that stalled front hanging over the center part of the state. Member Since: September 6, 2008 Posts: 0 Comments: 26

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