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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501. Levi32 9:32 PM GMT on September 28, 2010
A buoy south of TD #16's center is reporting a pressure of 997mb. Member Since: November 24, 2005 Posts: 586 Comments: 25450

503. DDR 9:33 PM GMT on September 28, 2010
Hurricanecat5 You wanted rain.... Now you got it,hope you don't get too much flood Member Since: April 27, 2007 Posts: 13 Comments: 1473

505. zoomiami 9:33 PM GMT on September 28, 2010
The problem with a system like this is it could turn like Bonnie, which was really the same as our afternoon thunderstorms, or it could be a mess like Katrina or Irene. Both of these last storms brought much more weather than anyone expected. Seems to me they are assuming that it won't be much weather. If that changes, there are going to be a lot of people on the road, and it will be a real mess. Member Since: August 13, 2007 Posts: 10 Comments: 4065

506. RotorYacht 9:33 PM GMT on September 28, 2010
I agree with you on this scenario. Let's wait and see... Quoting leo305: 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: August 28, 2008 Posts: 0 Comments: 57

508. FSUCOOPman 9:33 PM GMT on September 28, 2010
way to go out on a limb there :-P Member Since: August 29, 2008 Posts: 0 Comments: 332

509. Saltydogbwi1 9:34 PM GMT on September 28, 2010
Agreed Kman Member Since: October 21, 2009 Posts: 0 Comments: 276

510. victoriahurricane 9:34 PM GMT on September 28, 2010
Quoting CaptnDan142: Not random at all. It was by request. What other blog do you know of that has a purple hippo that takes requests? This is the only one in the universe I'd bet. Member Since: October 16, 2008 Posts: 0 Comments: 544

513. Stormchaser2007 9:34 PM GMT on September 28, 2010
Quoting futuremet: I doubt Nicole will look that good. Yeah. The upper-level environment isn't the only thing that is against it. There's also the amount of time until it becomes extra-tropical. UKM GFS Member Since: June 9, 2007 Posts: 4 Comments: 15248

514. leo305 9:34 PM GMT on September 28, 2010
Quoting Levi32: A buoy south of TD #16's center is reporting a pressure of 997mb. its relocating to the south.. were the highest convergence is located Member Since: April 17, 2010 Posts: 0 Comments: 1752

516. AllStar17 9:35 PM GMT on September 28, 2010
Levi - Any thoughts on a possible center SW of Jamaica? Member Since: June 29, 2009 Posts: 13 Comments: 5135

517. nash28 9:35 PM GMT on September 28, 2010
Still a little stymied as to how the NHC shifted the track further east on the 5pm as opposed to west..... UKMET?? Need I say any more? They can't ignore the 18z.. Member Since: July 11, 2005 Posts: 190 Comments: 16972

518. wunderkidcayman 9:36 PM GMT on September 28, 2010
997.7mb here in WB Grand Cayman Member Since: June 13, 2009 Posts: 2 Comments: 5409

519. Stormchaser2007 9:36 PM GMT on September 28, 2010
Member Since: June 9, 2007 Posts: 4 Comments: 15248

520. weatherboyfsu 9:36 PM GMT on September 28, 2010
Tornado Warning SEVERE WEATHER STATEMENT NATIONAL WEATHER SERVICE MELBOURNE FL 534 PM EDT TUE SEP 28 2010 FLC097-282200- /O.CON.KMLB.TO.W.0033.000000T0000Z-100928T2200Z/ OSCEOLA- 534 PM EDT TUE SEP 28 2010 ...A TORNADO WARNING REMAINS IN EFFECT UNTIL 600 PM EDT FOR CENTRAL OSCEOLA COUNTY... AT 531 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO INDICATE A TORNADO. THIS TORNADO WAS LOCATED NEAR LAKE MARIAN...MOVING NORTH AT 30 MPH AND APPROACHING THE FLORIDA TURNPIKE. THE TORNADO WILL OTHERWISE REMAIN OVER MAINLY RURAL AREAS OF THE INDICATED COUNTY. PRECAUTIONARY/PREPAREDNESS ACTIONS... HEAVY RAINFALL MAY OBSCURE THIS TORNADO. THE SAFEST PLACE TO BE DURING A TORNADO IS IN A STRONG BUILDING ON THE LOWEST FLOOR...IN AN INTERIOR ROOM SUCH AS A BATHROOM OR CLOSET. KEEP AWAY FROM WINDOWS. GET UNDER A WORKBENCH OR OTHER PIECE OF STURDY FURNITURE. USE BLANKETS OR PILLOWS TO COVER YOUR BODY. && LAT...LON 2804 8100 2802 8100 2776 8101 2784 8125 2801 8127 TIME...MOT...LOC 2133Z 178DEG 27KT 2789 8113 $$ KELLY Member Since: July 17, 2005 Posts: 0 Comments: 1025

521. largeeyes 9:36 PM GMT on September 28, 2010
Gotta go get plywood. I'm in the sammywammy cone! Member Since: August 22, 2006 Posts: 0 Comments: 1381

522. Stormchaser2007 9:37 PM GMT on September 28, 2010
Member Since: June 9, 2007 Posts: 4 Comments: 15248

523. southbeachdude 9:37 PM GMT on September 28, 2010
Quoting nash28: Still a little stymied as to how the NHC shifted the track further east on the 5pm as opposed to west..... UKMET?? Need I say any more? They can't ignore the 18z.. The shield around the Tampa area.....lol Member Since: July 29, 2005 Posts: 2 Comments: 694

525. A4Guy 9:37 PM GMT on September 28, 2010
wouldn't be surprised to see TD16 degenearte into an open wave....the COC looks very poorly defined, and when it starts moving into the shear from the front...could easily rip it open. Earlier today, it seemed as though things were tightening up...but really nothing impressive is going on...at this point. who knows what tonight might bring. Member Since: June 23, 2006 Posts: 0 Comments: 646

526. victoriahurricane 9:37 PM GMT on September 28, 2010
Vorticity has consolidated from yesterday Link Member Since: October 16, 2008 Posts: 0 Comments: 544

527. bwi 9:38 PM GMT on September 28, 2010
Here's earlier data from that buoy south of the Caymans at 17, 81.5. Latest pressure is 1000mb. 09 28 3:50 pm W 11.0 14.0 2.3 8 5.4 - 1000.9 -2.4 25.6 29.2 24.8 - - - 09 28 2:50 pm W 9.0 11.0 2.5 8 5.5 - 1001.8 -2.0 25.9 29.2 24.9 - - - 09 28 1:50 pm SW 12.0 15.0 2.5 7 5.5 - 1002.1 -2.2 28.1 29.2 24.9 - - - 09 28 12:50 pm SW 13.0 15.0 2.6 8 5.6 - 1003.3 -0.7 28.6 29.3 24.7 - - - 09 28 11:50 am SSW 13.0 16.0 2.6 8 5.5 - 1003.8 - 28.7 29.3 24.3 - - - 09 28 10:50 am SSW 14.0 16.0 2.7 8 5.7 - 1004.3 - 28.8 29.3 24.4 - - - 09 28 9:50 am SSW 13.0 15.0 3.0 7 5.8 - 1004.0 - 28.9 29.3 24.8 - - - Member Since: September 4, 2007 Posts: 0 Comments: 1134

528. weatherwatcher12 9:38 PM GMT on September 28, 2010
Good evening everyone. Weather station here in Jamaica reads 1002 mb and we've got 1.53 inches of rain since midnight. Member Since: May 16, 2009 Posts: 1 Comments: 1231

529. stormwatcherCI 9:38 PM GMT on September 28, 2010
Quoting Levi32: A buoy south of TD #16's center is reporting a pressure of 997mb. Pressure @ Grand Cayman is 997 mb too. Member Since: October 9, 2008 Posts: 0 Comments: 8039

530. NRAamy 9:38 PM GMT on September 28, 2010
Capt....thank you for validating my credentials... ;) Member Since: January 24, 2007 Posts: 315 Comments: 31937

531. Stormchaser2007 9:38 PM GMT on September 28, 2010
Member Since: June 9, 2007 Posts: 4 Comments: 15248

532. Levi32 9:38 PM GMT on September 28, 2010
Quoting weatherman12345: do you think there is a possible center relocation Quoting AllStar17: Levi - Any thoughts on a possible center SW of Jamaica? Not SW of Jamaica. There is the possibility of a weak competing mid-level center near 18N, 83.5W, but the circulation in general is very broad. There is a massive dimple of low pressure in the NW Caribbean right now illustrating a ton of heat, but it is not bundled. It is very spread out right now and that's why this system would require a good chunk of time to become a very formidable storm. Member Since: November 24, 2005 Posts: 586 Comments: 25450

533. TropicalAnalystwx13 9:39 PM GMT on September 28, 2010
Quoting A4Guy: wouldn't be surprised to see TD16 degenearte into an open wave....the COC looks very poorly defined, and when it starts moving into the shear from the front...could easily rip it open. Earlier today, it seemed as though things were tightening up...but really nothing impressive is going on...at this point. who knows what tonight might bring. A moderate TS Member Since: July 6, 2010 Posts: 89 Comments: 25284

534. Hurricanes101 9:39 PM GMT on September 28, 2010
Quoting nash28: Still a little stymied as to how the NHC shifted the track further east on the 5pm as opposed to west..... UKMET?? Need I say any more? They can't ignore the 18z.. they did not shift it east the 11am track was right on the coast of Florida, the 5pm track was to the West of Miami and Ft Lauderdale Member Since: March 10, 2010 Posts: 1 Comments: 6902

536. RotorYacht 9:39 PM GMT on September 28, 2010
Maybe because the center is relocating SW of Jamaica? Quoting nash28: Still a little stymied as to how the NHC shifted the track further east on the 5pm as opposed to west..... UKMET?? Need I say any more? They can't ignore the 18z.. Member Since: August 28, 2008 Posts: 0 Comments: 57

537. weatherboyfsu 9:40 PM GMT on September 28, 2010
BASED ON A BLEND OF THE AIRCRAFT...SURFACE...AND SATELLITE DATA THE CENTER HAS BEEN RELOCATED SLIGHTLY TO THE WEST OF THE PREVIOUS TRACK. NO SIGNIFICANT MODIFICATIONS HAVE BEEN MADE TO THE TRACK FORECAST OR SYNOPTIC REASONING. A CONTINUED NORTH-NORTHEASTWARD MOTION WITH ACCELERATION...BETWEEN THE AFOREMENTIONED TROUGH AND A MID-LEVEL ANTICYCLONE OVER THE WESTERN ATLANTIC...IS EXPECTED UNTIL THE SYSTEM DISSIPATES. THE TRACK FORECAST IS NOW A LITTLE TO THE EAST OF THE MODEL CONSENSUS BUT QUITE CLOSE TO THE NEW U.K. MET. OFFICE AND ECMWF GLOBAL MODEL TRACKS Nash, He said that it was moved to the west.... Im lost Member Since: July 17, 2005 Posts: 0 Comments: 1025

538. BLee2333 9:40 PM GMT on September 28, 2010
Quoting futuremet: I don't expect Nicole to look any better than this when it is over Florida. LOL, is that a 200nm eye forming in 474?? Member Since: January 6, 2009 Posts: 0 Comments: 217

539. Stormchaser2007 9:40 PM GMT on September 28, 2010
I'll have what the GFS is having. Member Since: June 9, 2007 Posts: 4 Comments: 15248

541. newportrinative 9:40 PM GMT on September 28, 2010
Quoting largeeyes: Gotta go get plywood. I'm in the sammywammy cone! LOL!!! Member Since: May 20, 2009 Posts: 0 Comments: 203

542. WeatherNerdPR 9:41 PM GMT on September 28, 2010
Good Afternoon. I see we have 016L (isn't the prettiest rose in the bunch). Funny it hasn't been for 12 hours and already has a Wiki Page lol. Member Since: July 7, 2010 Posts: 0 Comments: 5464

543. Levi32 9:41 PM GMT on September 28, 2010
That is a problem is the GFS initializing the pressure field a good 5mb too high in the NW Caribbean. Member Since: November 24, 2005 Posts: 586 Comments: 25450

544. CaptDanny 9:41 PM GMT on September 28, 2010
Preasure in uskin Fl is 1005 been falling for 14 hours Member Since: September 2, 2008 Posts: 0 Comments: 53

545. mcluvincane 9:41 PM GMT on September 28, 2010
I think the center may be reforming to the s east where the heaviest convection is. Very common with these monsoon systems Member Since: June 2, 2010 Posts: 0 Comments: 1315

546. Hurricanes101 9:41 PM GMT on September 28, 2010
Quoting Stormchaser2007: I'll have what the GFS is having. its just a feed back issue where the storm plot is connected back to the original position has no bearing on the validity of the forecast model run at all Member Since: March 10, 2010 Posts: 1 Comments: 6902

549. victoriahurricane 9:42 PM GMT on September 28, 2010
Quoting sammywammybamy: Expect a Tad Shift Left at 11pm. A tad? All the models have it landing west of the NHC and only 2 have it exiting florida to the east of NHC. I'm thinking there should be a pretty big shift at 11. Member Since: October 16, 2008 Posts: 0 Comments: 544

550. Clearwater1 9:42 PM GMT on September 28, 2010
Quoting nash28: Still a little stymied as to how the NHC shifted the track further east on the 5pm as opposed to west..... UKMET?? Need I say any more? They can't ignore the 18z.. * The 18z now just starting it's run now so let' see and, . . . I suppose the NHC can ignore whatever they please. Member Since: August 26, 2006 Posts: 0 Comments:** 1502

551. WeatherNerdPR 9:42 PM GMT on September 28, 2010
Quoting Stormchaser2007: I'll have what the GFS is having. Are they crazy?! Member Since: July 7, 2010 Posts: 0 Comments: 5464

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