Dr. Jeff Masters' WunderBlog

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

Posted by: Dr. Jeff Masters, 19:25 GMT le 28 septembre 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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451. Seastep 21:18 GMT le 28 septembre 2010
Pressure down to 998 at 42056 Guessing when they go back to the NHC position, pressure will be in the lower 990's Member Since: 9 septembre 2008 Posts: 6 Comments: 3406

452. Eugeniopr 21:18 GMT le 28 septembre 2010
Quoting weatherguy03: Afternoon Tropical Update Sept. 28th. 2010 Thank You Bob Member Since: 1 août 2010 Posts: 0 Comments: 229

453. largeeyes 21:18 GMT le 28 septembre 2010
Quoting mcluvincane: We are screwed here in Wilmington. All that rain is going to drown us. Would be worse if it had landfall west of you. Member Since: 22 août 2006 Posts: 0 Comments: 1381

454. FSUCOOPman 21:18 GMT le 28 septembre 2010
Quoting victoriahurricane: You can think whatever you like, I made a mistake I apologized end of story. Move on please. I think he meant that the 51.1 mph was screwy as well...coincidence... Member Since: 29 août 2008 Posts: 0 Comments: 332

455. leo305 21:18 GMT le 28 septembre 2010
looks like the LLC is falling apart.. and being sucked into the developing center south east of there... which means.... IF IT DOES re develop to the south the system may have MUCH more favorable conditions to develop over near 90 degree waters.. Member Since: 17 avril 2010 Posts: 0 Comments: 1752

457. PcolaDan 21:20 GMT le 28 septembre 2010
Quoting kmanislander: Not sure but 80 + winds would have been a long time ago LOL Well that's kinda what I was thinking. Either that or someone sneezed on the anemometer. Member Since: 22 août 2008 Posts: 12 Comments: 6008

458. victoriahurricane 21:20 GMT le 28 septembre 2010
Recon heading Northwest probably going for another center fix. Member Since: 16 octobre 2008 Posts: 0 Comments: 544

459. PRweathercenter 21:20 GMT le 28 septembre 2010
Blog Update Link Member Since: 21 juillet 2010 Posts: 58 Comments: 916

460. Stormchaser2007 21:20 GMT le 28 septembre 2010
Quoting futuremet: This system such a mess... It really is. I'd be very surprised if it was upgraded to a 50mph TS later tonight. Member Since: 9 juin 2007 Posts: 4 Comments: 15248

462. Grothar 21:22 GMT le 28 septembre 2010
Quoting Its2Humid: Still have my Blue Jays and Dove coming in the backyard. Am located out in west Broward (Plantation) Guess the other birds haven't told them yet. Member Since: 17 juillet 2009 Posts: 56 Comments: 19542

463. srada 21:22 GMT le 28 septembre 2010
Quoting mcluvincane: We are screwed here in Wilmington. All that rain is going to drown us. Well I wouldnt say "drown" but yeah we are screwed though..New Hanover County, Brunswick Country and Pender County will have major damage to property from the low lying roads and rivers overflowing.. Member Since: 17 août 2006 Posts: 1 Comments: 772

464. CosmicEvents 21:22 GMT le 28 septembre 2010
Quoting weatherman12345: They can always change the school closing right? They can..up to 11PM. But I don't see anything happening that fast to make them change their mind. I suppose that there could be an early morning announcment, but I hope that doesn't happen. . . The bottom line. You're gettin' up and going to school. Sorry. Member Since: 3 août 2005 Posts: 10 Comments: 5099

467. will40 21:23 GMT le 28 septembre 2010
Quoting largeeyes: Would be worse if it had landfall west of you. gonna be west of me on that track Member Since: 19 septembre 2005 Posts: 2 Comments: 3439

468. NRAamy 21:23 GMT le 28 septembre 2010
Fine...run for your life...happy now? Member Since: 24 janvier 2007 Posts: 315 Comments: 31937

470. gordydunnot 21:23 GMT le 28 septembre 2010
Anybody want to play a card game. pick a center, pick a center, any center in the deck. Member Since: 18 août 2008 Posts: 0 Comments: 3044

471. Radioman300900 21:23 GMT le 28 septembre 2010
With were they have the track now Palm Beach County coastal areas are going to get the worst side. Suprised that schools arent closed due to safety issues. Member Since: 29 juillet 2010 Posts: 0 Comments: 11

473. caneswatch 21:24 GMT le 28 septembre 2010
Quoting weatherman12345: They can always change the school closing right? Yes. When Katrina was about to come through, they called for a half-day on Thursday and an off-day Friday at 8pm Wednesday. Member Since: 8 octobre 2008 Posts: 14 Comments: 4473

474. futuremet 21:24 GMT le 28 septembre 2010
I don't expect Nicole to look any better than this when it is over Florida. Member Since: 19 juillet 2008 Posts: 43 Comments: 4049

475. FloorManBroward 21:24 GMT le 28 septembre 2010
Quoting Grothar: Anybody in the Ft. Lauderdale area notice there are no birds around? Actually I heard a couple of mocking birds singing away right before it started to rain around 4:30. I thought that they were happy so everything must be OK Member Since: 25 août 2005 Posts: 0 Comments: 61

476. HCW 21:24 GMT le 28 septembre 2010
Tornado Warning FL zoomed in GREARTH Member Since: 10 août 2002 Posts: 0 Comments: 1280

477. weatherguy03 21:25 GMT le 28 septembre 2010
Quoting CosmicEvents: They can..up to 11PM. But I don't see anything happening that fast to make them change their mind. I suppose that there could be an early morning announcment, but I hope that doesn't happen. . . The bottom line. You're gettin' up and going to school. Sorry. Alittle rain and alittle wind. You can handle it!..LOL Member Since: 5 juillet 2005 Posts: 581 Comments: 29680

478. 1900hurricane 21:25 GMT le 28 septembre 2010
There's not really much there: Member Since: 2 août 2006 Posts: 43 Comments: 10366

479. CybrTeddy 21:25 GMT le 28 septembre 2010
Must admit, I'm impressed TD16 has sub-1000 mb pressures. That's pretty rare. Discussion seems to indicate that TD16 might have been a TS earlier. Recon reports are starting to show TS winds as just posted, we'll need to see if there is consistency associated it. A very disorganized TD though. Member Since: 8 juillet 2005 Posts: 253 Comments: 20251

481. Stormchaser2007 21:26 GMT le 28 septembre 2010
Rules of the Road 5)Do not circumvent administrative action by creating new users, etc. Member Since: 9 juin 2007 Posts: 4 Comments: 15248

482. bwi 21:27 GMT le 28 septembre 2010
Quoting Seastep: Pressure down to 998 at 42056 Guessing when they go back to the NHC position, pressure will be in the lower 990's And a ship report at 21z of 997 nearby too: SHIP S 2100 19.90 -83.60 217 215 290 5.7 - 1.0 3.0 - - 997.0 Member Since: 4 septembre 2007 Posts: 0 Comments: 1134

483. futuremet 21:28 GMT le 28 septembre 2010
The low pressures found in this system are not really that impressive. This is because the surrounding pressure is very low (below 1010mb). The pressure gradient or difference is what matters. Member Since: 19 juillet 2008 Posts: 43 Comments: 4049

484. tiggeriffic 21:29 GMT le 28 septembre 2010
my weather bug went off a lil bit ago....according to it, landfall close to charleston, sc on that system with 50-60 mph winds and monsoon type rain Member Since: 16 septembre 2007 Posts: 0 Comments: 3592

485. futuremet 21:29 GMT le 28 septembre 2010
Quoting Stormchaser2007: Rules of the Road 5)Do not circumvent administrative action by creating new users, etc. Say that to Jasonxxxxxx Member Since: 19 juillet 2008 Posts: 43 Comments: 4049

488. CycloneUK 21:29 GMT le 28 septembre 2010
Member Since: 5 Mars 2010 Posts: 0 Comments: 39

489. Stormchaser2007 21:29 GMT le 28 septembre 2010
I remember the day that Barry formed. Was a crazy day on here. Member Since: 9 juin 2007 Posts: 4 Comments: 15248

490. mbjjm 21:29 GMT le 28 septembre 2010
Important section of the NHC 5pm edt discussion AIR FORCE HURRICANE HUNTERS FOUND THAT THE LOW-LEVEL CENTER CONSISTED OF A BROAD AREA OF LIGHT WINDS AND NEARLY UNIFORM PRESSURE. INDEED...WINDS WERE 20 KT OR LESS WITHIN 100 N MI OR MORE OF THE CENTER. CLEARLY...THIS IS NOT A CLASSICAL TROPICAL CYCLONE AND THE MAXIMUM WINDS ARE LOCATED SOME 200 N MI SOUTHEAST OF THE CENTER. OBSERVATIONS FROM NOAA DATA BUOY 42057 FROM EARLY THIS MORNING AND ASCAT DATA FROM AROUND 1500 UTC SUGGESTED THAT THE SYSTEM MAY HAVE BEEN A MARGINAL TROPICAL STORM EARLIER TODAY. THERE IS SOME QUESTION...HOWEVER...AS TO WHETHER THOSE WINDS WERE REPRESENTATIVE OF THE CYCLONE SCALE. IN ANY EVENT...RECENT HURRICANE HUNTER DATA SHOWS NO EVIDENCE OF TROPICAL STORM FORCE WINDS AT THIS TIME. THE SATELLITE PRESENTATION IS NOT VERY IMPRESSIVE...WITH RAGGED-LOOKING BANDING FEATURES AND VERY LITTLE DEEP CONVECTION NEAR THE CENTER. SOUTH-SOUTHWESTERLY VERTICAL SHEAR ASSOCIATED WITH A LARGE MID- TO UPPER-LEVEL TROUGH MOVING OVER THE SOUTHEASTERN UNITED STATES...ALONG WITH THE CURRENT STRUCTURE OF THE CYCLONE...SHOULD LIMIT INTENSIFICATION OVER THE NEXT DAY OR SO. THE OFFICIAL INTENSITY FORECAST IS A LITTLE HIGHER THAN THE LATEST STATISTICAL/DYNAMICAL LGEM PREDICTION. GLOBAL MODEL GUIDANCE INDICATES THAT THE SYSTEM SHOULD MERGE WITH A FRONT AND BECOME EXTRATROPICAL IN ABOUT 36 TO 48 HOURS. AFTER THAT...THE MODELS ALSO SHOW WHAT APPEARS TO BE A NEW BAROCLINIC DEVELOPMENT TO THE NORTH REPLACING THE FORMER TROPICAL CYCLONE...SO DISSIPATION IS EXPECTED BY 72 HOURS. Member Since: 23 août 2010 Posts: 0 Comments: 310

491. futuremet 21:30 GMT le 28 septembre 2010
Quoting Stormchaser2007: I remember the day that Barry formed. Was a crazy day on here. I doubt Nicole will look that good. Member Since: 19 juillet 2008 Posts: 43 Comments: 4049

492. Saltydogbwi1 21:30 GMT le 28 septembre 2010
Quoting kmanislander: Not sure but 80 + winds would have been a long time ago LOL I believe the aircraft jetwash interferes with this station as it is at the airport there have been many questionable wind speed readings over the last year Member Since: 21 octobre 2009 Posts: 0 Comments: 276

493. CycloneUK 21:31 GMT le 28 septembre 2010
Strange, I see the system as quite organised. Member Since: 5 Mars 2010 Posts: 0 Comments: 39

494. Stormchaser2007 21:31 GMT le 28 septembre 2010
Quoting futuremet: Say that to Jasonxxxxxx lol About 50% of my ignore list consist of the JFV and Jason handles. Member Since: 9 juin 2007 Posts: 4 Comments: 15248

495. TropicalAnalystwx13 21:31 GMT le 28 septembre 2010
Quoting futuremet: I doubt Nicole will look that good. Now your just over-exagerrating. Plus, it doesn't really matter how it looks. If it has the winds...There you go. Member Since: 6 juillet 2010 Posts: 89 Comments: 25314

497. nash28 21:32 GMT le 28 septembre 2010
We do not need monsoon rain here in Charleston. Market St. downtown floods when someone sweats heavily. Member Since: 11 juillet 2005 Posts: 190 Comments: 16972

498. RotorYacht 21:32 GMT le 28 septembre 2010
Great.. Can't wait to have water restrictions again. Quoting seflagamma: 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: 28 août 2008 Posts: 0 Comments: 57

499. kmanislander 21:32 GMT le 28 septembre 2010
Quoting Saltydogbwi1: I believe the aircraft jetwash interferes with this station as it is at the airport there have been many questionable wind speed readings over the last year Even so the barometer is correct and right now 997.6 is where we are at. Member Since: 19 août 2006 Posts: 0 Comments: 14939

500. victoriahurricane 21:32 GMT le 28 septembre 2010
Quoting NRAamy: Not random...check out the previous page... -2 points for not keeping up with the rest of us..... Back to the weather.... D'oh, my apologies. Member Since: 16 octobre 2008 Posts: 0 Comments: 544

501. Levi32 21:32 GMT le 28 septembre 2010
A buoy south of TD #16's center is reporting a pressure of 997mb. Member Since: 24 novembre 2005 Posts: 586 Comments: 25450

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