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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651. GoodOleBudSir 10:15 PM GMT on September 28, 2010
Quoting tiggeriffic: roflmbo...don't offer HIM that...he'd take you up on it!!! sure...a 6 year old as your designated driver...i can see it now...hope your insurance is paid up! roflmbo You don't like to swear do you tigger? Member Since: July 30, 2008 Posts: 0 Comments: 261

653. Alockwr21 10:15 PM GMT on September 28, 2010
Expecting a big rain maker here in Raleigh,NC Member Since: September 12, 2007 Posts: 0 Comments: 724

654. tiggeriffic 10:16 PM GMT on September 28, 2010
Quoting Chucktown: Hey Press and Tig - not much of an impact expected here in Charleston. Mainly a heavy rain set up late tonight and Wednesday. Most of the wind impact will be near Myrtle Beach and eastern NC. In fact, when the center of the storm is just east of us on Thursday, our weather will begin to clear out. There is going to be a very sharp moisture gradient with this. I-95 east will be quite wet, but once you get out towards Columbia, very little rain. my concern is almost every system keeps inching west this year from the "expected" tracks...just makin sure i have extra batteries for the game boy roflmbo Member Since: September 16, 2007 Posts: 0 Comments: 3592

655. presslord 10:16 PM GMT on September 28, 2010
Quoting Chucktown: Hey Press and Tig - not much of an impact expected here in Charleston. Mainly a heavy rain set up late tonight and Wednesday. Most of the wind impact will be near Myrtle Beach and eastern NC. In fact, when the center of the storm is just east of us on Thursday, our weather will begin to clear out. There is going to be a very sharp moisture gradient with this. I-95 east will be quite wet, but once you get out towards Columbia, very little rain. Don't you expect they'll shut the schools down due to the water? Member Since: August 13, 2007 Posts: 0 Comments: 10377

657. avthunder 10:16 PM GMT on September 28, 2010
Quoting sammywammybamy: Looking East - South Palm Beach County. Great picture - that is near where I work. We could see the dark clouds coming in from our office - awesome. Dog is under the bed, so it will be a stormy night. Member Since: August 30, 2010 Posts: 0 Comments: 245

659. tiggeriffic 10:16 PM GMT on September 28, 2010
Quoting GoodOleBudSir: You don't like to swear do you tigger? rolling on the floor laughing my BUTT of isn't swearing...snicker snicker snort snort Member Since: September 16, 2007 Posts: 0 Comments: 3592

660. Levi32 10:16 PM GMT on September 28, 2010
It's really cool how easy it is. Can you see the track? It's painted out for you on the satellite image as clear as day. Member Since: November 24, 2005 Posts: 586 Comments: 25450

661. breald 10:17 PM GMT on September 28, 2010
Quoting Levi32: Not dissipate, extratropical transition.....that's the whole problem with stripping away the name while it's still causing tropically-induced dangerous weather. Of course it will be partly non-tropical but keep the name....that way people know to be prepared. It won't be like a regular frontal wave it will obviously be tropical in origin and people will know it when it passes over. Thanks Levi!! BTW, when you become a famous meteorologist will you go by the name Levi? How will all your WU friends know it is you...LOL Member Since: May 28, 2008 Posts: 38 Comments: 5298

662. GoodOleBudSir 10:17 PM GMT on September 28, 2010
Quoting tiggeriffic: rolling on the floor laughing my BUTT of isn't swearing...snicker snicker snort snort that was my point. LOL Member Since: July 30, 2008 Posts: 0 Comments: 261

663. stormpetrol 10:18 PM GMT on September 28, 2010
I call TD#16 meandering or even drifting westward. Member Since: April 29, 2007 Posts: 0 Comments: 6396

664. MiamiHurricanes09 10:18 PM GMT on September 28, 2010
The center of circulation of 16L has evidently consolidated and grown in vigor. Below is the 850mb vorticity graph valid 6 hours ago (11a.m EDT). Now here's the current one valid as of 5p.m EDT. Member Since: September 2, 2009 Posts: 129 Comments: 19976

665. Levi32 10:18 PM GMT on September 28, 2010
Quoting Hoff511: Levi, Do you think this has any chance of becoming a hurricane before FL landfall? The NHC gives 3% chance in next 24hrs, so it is still a small possibility to them, but I know they are usually conservative in their percentages. It seems the shear from the cold front will prevent intensification, but I still worry about something coming out of that area. No no hurricane before Florida, though I do worry about the possibility for hurricane-force gusts in the Carolinas when this goes through there. Member Since: November 24, 2005 Posts: 586 Comments: 25450

666. aspectre 10:18 PM GMT on September 28, 2010
TropicalDepression16's heading had turned eastward to (8.9degrees east of) dueNorth from its previous heading of dueNorth TD.16's average speed moving between its last 2 reported positions was ~14mph(~22.5km/h) Invest96L : NHC-ATCF 27Sep 12pmGMT - - 18.5n85.5w - - 25knots -- 1003mb - - NHC-ATCF 27Sep 06pmGMT - - 19.0n84.7w - - 25knots -- 1003mb - - NHC-ATCF 28Sep 12amGMT - - 19.4n84.1w - - 25knots -- 1003mb - - NHC-ATCF 28Sep 06amGMT - - 19.8n83.5w - - 30knots -- 1003mb - - NHC-ATCF 28Sep 12pmGMT - - 20.4n83.0w - - 30knots -- 1001mb - - NHC-ATCF 25knots=~28.8mph=46.3km/h __ 30knots=~34.5mph=~55.6km/h 96L becomes TD.16 28Sep 03pmGMT - - 20.6n82.5w - - 35mph - - - 1001mb - - NHC.Adv.#1 28Sep 06pmGMT - - 20.9n82.5w - - 35mph - - - 1000mb - - #1A 28Sep 09pmGMT - - 21.5n82.4w - - 35mph - - - - 999mb - - #2 35mph=~56.4km/h Copy &paste 18.0n85.5w, 18.3n84.6w, 18.7n83.9w, 19.4n83.3w-20.2n82.8w, 20.2n82.8w-20.6n82.5w, 20.6n82.5w-20.9n82.5w, 20.9n82.5w-21.5n82.4w, ctm, hav, pot into the GreatCircleMapper for a look at the last 15hours. The 3 northernmost line-segments span 3hours between dots. The following line-segment spans 6hours between dots. Member Since: August 21, 2007 Posts: 0 Comments: 4846

667. oceanblues32 10:18 PM GMT on September 28, 2010
I am located in dania beach fl just north of hollywood and miami and it is raining hard hear and very dark with thunder Member Since: November 8, 2009 Posts: 0 Comments: 207

668. PalmBeachWeatherBoy 10:19 PM GMT on September 28, 2010
Palm Beach County schools will open Wednesday despite storm and flood warnings from what could soon be Tropical Storm Nicole, district officials announced late today. Member Since: August 30, 2006 Posts: 1 Comments: 433

669. GoodOleBudSir 10:19 PM GMT on September 28, 2010
Quoting cat5hurricane: Poor dog. Well looking at the latest nexrad loop, it looks like you'll get a break in the next half an hour or so. I'd take him then. Thanks C5H Member Since: July 30, 2008 Posts: 0 Comments: 261

670. tiggeriffic 10:19 PM GMT on September 28, 2010
Quoting GoodOleBudSir: that was my point. LOL he he he....i try very hard not to swear...the only ones i say are in the bible... =) but they work...especially when i need to call someone a donkey snicker snicker Member Since: September 16, 2007 Posts: 0 Comments: 3592

671. HellaGoose 10:19 PM GMT on September 28, 2010
Does the center seem to be relocating SW near Gran C. to anyone else? Member Since: September 18, 2009 Posts: 0 Comments: 30

672. StormFreakyisher 10:19 PM GMT on September 28, 2010
. Member Since: May 16, 2009 Posts: 0 Comments: 684

673. MiamiHurricanes09 10:20 PM GMT on September 28, 2010
Quoting Levi32: It's really cool how easy it is. Can you see the track? It's painted out for you on the satellite image as clear as day. Pretty interesting. Looks like it will scrape along the eastern Florida coast before making it to South and North Carolina. Member Since: September 2, 2009 Posts: 129 Comments: 19976

674. presslord 10:20 PM GMT on September 28, 2010
Quoting Levi32: No no hurricane before Florida, though I do worry about the possibility for hurricane-force gusts in the Carolinas* when this goes through there.* ...gggrrrr... Member Since: August 13, 2007 Posts: 0 Comments: 10377

676. PcolaDan 10:20 PM GMT on September 28, 2010
Member Since: August 22, 2008 Posts: 12 Comments: 6008

677. GoodOleBudSir 10:20 PM GMT on September 28, 2010
Quoting tiggeriffic: he he he....i try very hard not to swear...the only ones i say are in the bible... =) but they work...especially when i need to call someone a donkey snicker snicker LOL Member Since: July 30, 2008 Posts: 0 Comments: 261

678. Levi32 10:20 PM GMT on September 28, 2010
Quoting breald: Thanks Levi!! BTW, when you become a famous meteorologist will you go by the name Levi? How will all your WU friends know it is you...LOL Well I don't plan on being famous, but I like to be known by my first name, which is Levi. Member Since: November 24, 2005 Posts: 586 Comments: 25450

680. tiggeriffic 10:21 PM GMT on September 28, 2010
Quoting Levi32: No no hurricane before Florida, though I do worry about the possibility for hurricane-force gusts in the Carolinas when this goes through there. that's what i heard...50-60mph winds with higher gusts even in charleston Member Since: September 16, 2007 Posts: 0 Comments: 3592

681. CaptnDan142 10:21 PM GMT on September 28, 2010
Quoting StormFreakyisher: So is there school tomorrow for Palm Beach County? School board has no website? No local media? This just seems an odd place to ask that question. Member Since: August 21, 2007 Posts: 0 Comments: 856

682. Levi32 10:21 PM GMT on September 28, 2010
Quoting presslord: ...gggrrrr... Hey now last I heard you need the rain =P Member Since: November 24, 2005 Posts: 586 Comments: 25450

683. Hurricanes101 10:21 PM GMT on September 28, 2010
Quoting Levi32: It's really cool how easy it is. Can you see the track? It's painted out for you on the satellite image as clear as day. How about that track? Member Since: March 10, 2010 Posts: 1 Comments: 6902

684. K8eCane 10:22 PM GMT on September 28, 2010
Here in Wilmington Nc it wont take much wind to fell a lot of trees Member Since: April 26, 2006 Posts: 5 Comments: 2371

685. CaptnDan142 10:22 PM GMT on September 28, 2010
Quoting presslord: ...gggrrrr... Well who didn't see that coming a mile away... ;-) Member Since: August 21, 2007 Posts: 0 Comments: 856

686. BLee2333 10:22 PM GMT on September 28, 2010
Quoting charlottefl: Current steering setup: I'm reading another shift to the left in it's future... Member Since: January 6, 2009 Posts: 0 Comments: 217

687. KmanGal 10:22 PM GMT on September 28, 2010
Quoting StormFreakyisher: So is there school tomorrow for Palm Beach County? Glad that it's not just my eyes....I thought it was only me seeing that!! Member Since: August 26, 2008 Posts: 0 Comments: 14

688. Seastep 10:22 PM GMT on September 28, 2010
I think I figured out the pressure at GC vs at the center strangeness. At 4pm, recon was pretty close to GC and pressure readings were 1000+. Weather stations were reading 998 that time, so the extrapolated surface pressure is off by 2mb as calibration. Something to consider. Member Since: September 9, 2008 Posts: 6 Comments: 3406

689. presslord 10:23 PM GMT on September 28, 2010
Quoting Levi32: Hey now last I heard you need the rain =P that was before yesterday, dude...we're good now ; ) Member Since: August 13, 2007 Posts: 0 Comments: 10377

690. Hoff511 10:23 PM GMT on September 28, 2010
Thanks Levi. and I agree the "track" you posted is pretty awesome. Member Since: September 2, 2009 Posts: 0 Comments: 254

691. tiggeriffic 10:23 PM GMT on September 28, 2010
Quoting Levi32: Hey now last I heard you need the rain =P we just got pounded with rain...actually filled up a kiddie pool in my back yard and it wasn't even down from the time it started... flipped over about 6 hours into the rain Member Since: September 16, 2007 Posts: 0 Comments: 3592

693. NRAamy 10:25 PM GMT on September 28, 2010
"the Carolinas"!!!!!! Hahahahahahahahahahahaha!!! Member Since: January 24, 2007 Posts: 315 Comments: 31937

694. MiamiHurricanes09 10:25 PM GMT on September 28, 2010
Quoting weatherman12345: from sunsentinal at 5:00 pm "Broward district administrators said they will continue to monitor weather reports. Sustained wind speeds must reach 40 mph before school are closed, officials said. How about for Dade? And, does the system need to have 40mph winds or do 40mph sustained winds need to be felt in that specific county? Member Since: September 2, 2009 Posts: 129 Comments: 19976

695. tiggeriffic 10:25 PM GMT on September 28, 2010
Quoting weatherman12345: from sunsentinal at 5:00 pm "Broward district administrators said they will continue to monitor weather reports. Sustained wind speeds must reach 40 mph before school are closed, officials said. not in Charleston, they close the bridges at 40mph winds....and since the whole area is nothing but bridges over rivers and tidal areas....well...needless to say Member Since: September 16, 2007 Posts: 0 Comments: 3592

696. Chucktown 10:26 PM GMT on September 28, 2010
Quoting tiggeriffic: my concern is almost every system keeps inching west this year from the "expected" tracks...just makin sure i have extra batteries for the game boy roflmbo Unless there is a drastic shift to the track, we will be on the left side of this storm. All the wind and squally weather is on the SE side. We'll still have the potential to get 3-4 inches of rain here in Charleston, but I just don't see the wind impact here. Member Since: August 27, 2006 Posts: 0 Comments: 1383

697. K8eCane 10:26 PM GMT on September 28, 2010
ya got NORTH carolina and ya got SOUTH carolina Member Since: April 26, 2006 Posts: 5 Comments: 2371

699. Hurricanes101 10:26 PM GMT on September 28, 2010
recon found east winds at 20.8, how can the center be at 21.5? Member Since: March 10, 2010 Posts: 1 Comments: 6902

700. CosmicEvents 10:27 PM GMT on September 28, 2010
Quoting Hurricanes101: You know how this blog works If there is not an eye by tonight, it will be RIP LOL That's for sure. If it's still a depression at 11 then there's going to be serious depression on this blog. . . . Especially if they decide to keep the schools open! Member Since: August 3, 2005 Posts: 10 Comments: 5099

701. Levi32 10:27 PM GMT on September 28, 2010
Quoting Hurricanes101: How about that track? I think a nudge farther west. Think about where pressures are going to be lowering the most underneath that frontal boundary, and then think about how the trough is diving into Alabama trying to phase in that low pressure. Member Since: November 24, 2005 Posts: 586 Comments: 25450

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