Dr. Jeff Masters' WunderBlog

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

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

The large area of low pressure centered just south of Cuba's Isle of Youth has developed enough of a well-defined circulation to be classified as Tropical Depression Sixteen, and is likely to become Tropical Storm Nicole by Wednesday. The depression has a very broad center, with little heavy thunderstorm activity near the center, and is this very dissimilar to the usual types of tropical depressions we see in the Atlantic. The large size, broad center, and lack of heavy thunderstorm activity near the center of TD 16 will limit the storm's ability to rapidly intensify. TD 16 resembles the "monsoon depressions" common in India's Bay of Bengal or the Western Pacific. A monsoon depression is similar to a regular tropical depression in the winds that it generates--about 30 - 35 mph near the outer edges (and usually stronger on the eastern side of the circulation.) Monsoon depressions have large, calm centers, and can evolve into regular tropical storms, if given enough time over water to develop a tight, closed circulation. Today's monsoon-like depression in the Caribbean was able to form because the atmospheric flow pattern of the Eastern Pacific has shifted eastwards into the Western Caribbean, bringing in the Eastern Pacific ITCZ (Intertropical Convergence Zone, a region of converging surface winds that creates a band of strong thunderstorms). This unusual flow pattern is forecast to remain in place for at least the next ten days.

An Air Force hurricane hunter aircraft has been flying at 700 feet in TD 16 since 1:30pm EDT, and has thus far found a central pressure of 999 mb. The strongest winds at flight level seen as of 3:20pm EDT were 32 mph, located about 100 miles east of the center of TD 16. Surface observations show that the strongest winds at any surface station continue to be at Buoy 42057, several hundred miles to the southeast of TD 16's center. Winds were 27 mph, gusting to 34 mph at 2:43pm EDT this afternoon. Rotation of TD 16 can be seen on radar loops out of Pico San Juan, Cuba, and well as satellite imagery. The heavy thunderstorms are currently quite disorganized, but a curved band is beginning to wrap around the north side of the center, signaling that TD 16 is growing more organized. TD 16 has brought torrential rains to the Cayman Islands, Jamaica, Cuba, and Honduras today.

Figure 1. Radar-estimated precipitation for South Florida and Cuba. TD 16 has brought 2 - 4 inches of rains to the region.

Forecast for TD 16
Because TD 16 is so large, it will take more time than a typical depression for it to spin up into a strong tropical storm. Given that the steering currents are expected to pull TD 16 north-northeastwards over Cuba and into South Florida and the western Bahamas on Wednesday, the storm lacks sufficient time over water to be any stronger than a 50 mph tropical storm for Florida. TD 16 is organizing pretty slowly this afternoon, and I think the top winds in Southeast Florida are most likely to be in the 25 - 35 mph range on Wednesday. Winds are likely to be stronger in the western Bahamas, perhaps 30 - 40 mph, since they will be in the stronger right front quadrant of the storm. By the time TD 16 makes landfall in South Carolina or North Carolina on Thursday morning, it could be as strong as a 50 - 60 mph tropical storm. However, wind shear will increase sharply on Thursday as TD 16 gets caught in an upper-level trough of low pressure, and NHC is giving TD 16 only a 9% chance of making it to hurricane strength before it becomes an extratropical storm on Thursday. The primary danger from TD 16 is not wind, but heavy rainfall. A potent upper-level low and stationary front over the U.S. East Coast have been pulling moist, tropical air from the Caribbean northwards over the past few days, bringing heavy rains that have saturated the soils. This is called a Predecessor Rain Event, or PRE, since it comes in advance of the actual rain shield of the storm. (A PRE from Hurricane Karl brought southern Wisconsin the heavy rain that caused the levee on the Wisconsin River to fail yesterday.) Wilmington, NC received 10.33 inches of rain yesterday, its second greatest one-day rainfall since record keeping began in 1871. Only the 13.38" that fell during Hurricane Floyd on September 15, 1999 beat yesterday's rainfall total. With TD 16 expected to bring another 6 - 8 inches of rain to the region later this week, serious flooding is likely, and flash flood watches are posted for the North Carolina/ South Carolina border region. South Florida is also under a flood watch, for 3 - 5 inches of rain. Flooding rains of similar magnitude can also be expected in Cuba, the Cayman Islands, and the Western Bahamas through Wednesday night. Both the GFDL and HWRF models are predicting that TD 16 will dump rains in excess of eight inches along narrow portions of its path in eastern Florida, South Carolina, and North Carolina.

Figure 2. Forecast precipitation for the 5-day period from 8am today through 8am EDT Sunday, October 3, 2010. Image credit: NOAA Hydrometeorological Prediction Center.

Up to 1,000 feared dead in Mexican landslide
Mexico has taken the brunt of the devastation from the hurricane season of 2010, thanks to the landfalls of this year's two deadliest and most damaging storms, Hurricanes Alex and Karl. But Mexico's worst blow yet hit this morning, when heavy rains from the remnants of Tropical Storm Matthew triggered a landslide in Mexico's mountainous Oaxaca state that buried as many as 1,000 people in Santa Maria Tlahuitoltepec, a town of 9,000. Rescuers have not reached the area yet, but hundreds are feared dead in the 300 homes that were buried by the early morning landslide. Matthew hit Belize on Saturday as a minimal tropical storm with 40 mph winds, and dissipated Sunday over southern Mexico. However, Matthew's remains stalled out over the region of Mexico that had already received torrential rains from Hurricane Karl, which hit on September 18. Satellite estimates of Matthew's rains over southern Mexico (Figure 3) show that a foot of rain may have fallen in the landslide area. Matthew's remains still linger over the region, but are probably only capable of bringing 1 - 2 inches of additional rain through Thursday.

Figure 3. Satellite-estimated rainfall for the five-day period ending at 8pm EDT Monday September 27, 2010. The dark green colors show where rainfall amounts of 300 mm (about 12 inches) fell, due to the remnants of Tropical Storm Matthew. Image credit: Navy Research Lab, Monterey.

Elsewhere in the tropics
Once TD 16 moves out of the Caribbean, the GFS model predicts that the Western Caribbean will "reload" and produce another tropical disturbance capable of developing into a tropical depression early next week. The GFS also predicts a tropical or subtropical storm will form over the Bahamas late this week, and move north-northeast along the U.S. East Coast, missing hitting land. The NOGAPS model hints at the Bahamas storm, and also predicts development of a tropical wave a few hundred miles northeast of the Lesser Antilles Islands, about a week from now.

Hottest day in Los Angeles history
The mercury hit a blistering 113°F (45.0°C) at 12:15 pm PDT yesterday in downtown Los Angeles, making it the hottest day in Los Angeles history. It may have gotten hotter, but the thermometer broke shortly after the record high was set. The previous record in Los Angeles was 112°F set on June 26, 1990; records go back to 1877. Nearby Long Beach tied its hottest all-time temperature yesterday, with a scorching 111°F. And Christopher C. Burt, our new featured blogger on weather records, pointed out to me that a station in the foothills at 1260' elevation near Beverly Hills owned by the Los Angeles Fire Department hit 119°F yesterday--the hottest temperature ever measured in the Los Angeles area, tying the 119°F reading from Woodland Hills on July 22, 2006. Yesterday's record heat was caused by an unusually large and intense upper-level high pressure system centered over Nevada that generated winds blowing from the land to the ocean, keeping the ocean from exerting its usual cooling influence. Remarkably, Los Angeles had its second coldest summer on record this year, and temperatures just five days ago were some the coldest September temperatures in the region for the past 50 years.

The remarkable summer of 2010
Wunderground is pleased to welcome a new featured blogger--weather historian Christopher C. Burt. Chris is a leading expert in the U.S. on weather records, and is author of the world's most popular weather records book published to date, Extreme Weather: A Guide and Record Book. He's spent a lifetime collaborating with like-minded individuals from around the world, and no one--including official sources such as the National Climatic Data Center and the National Extremes Committee--has done as thorough a job correlating the various weather records available and determining the most accurate extreme values of such. Each month he'll be reporting on the notable records for heat, cold, and precipitation set world-wide, and his first post takes a look at the remarkable summer of 2010. It's great to have someone like Chris who stays on top of weather extremes, and I hope you'll pay a visit to his blog and welcome him to the wunderground site!

"Hurricane Haven" airing this afternoon
My live Internet radio show, "Hurricane Haven", will be airing again today at 4pm EDT. The call in number is 415-983-2634, or you can post a question to broadcast@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line.

Today's show will be about 30 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

I'll have updates as the situation with TD 16 requires.

Jeff Masters

Alone again, naturally (ftogrf)

Lonely Seagull, as a storm associated with TD 16 is approaching.

Categories: Hurricane

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1001. stormy2008 11:36 PM GMT on September 28, 2010
Something tells me we may be looking at a system similar to last year's "November Nor'Easter"... or then again... this could be the 'new' perfect-storm. Member Since: August 18, 2008 Posts: 4 Comments: 215

1002. NRAamy 11:36 PM GMT on September 28, 2010
"goat-casting"? What about purple-hippo-casting? That's when the caster has nothing relevant to the topic to say, and so instead posts lame jokes..... Member Since: January 24, 2007 Posts: 315 Comments: 31937

1003. Seastep 11:37 PM GMT on September 28, 2010
Quoting Stormchaser2007: Ah LOL I was gonna say... Sooo glad I clarified. LOL. Read it back and realized that with the double quote it could be taken wrong. Member Since: September 9, 2008 Posts: 6 Comments: 3406

1004. nash28 11:37 PM GMT on September 28, 2010
I'm concerned after the moonwalk and Nicole roll through, Summerville will be Riverville for a few days. Member Since: July 11, 2005 Posts: 190 Comments: 16972

1005. Stormchaser2007 11:37 PM GMT on September 28, 2010
Member Since: June 9, 2007 Posts: 4 Comments: 15249

1007. Levi32 11:38 PM GMT on September 28, 2010
Quoting barotropic: By the way I wanted to complement you a=on your informative video today. Thanks. Thank you. Member Since: November 24, 2005 Posts: 587 Comments: 25459

1008. wunderkidcayman 11:38 PM GMT on September 28, 2010
I say the COC of TD 16 is near 18N or 19N Member Since: June 13, 2009 Posts: 2 Comments: 5511

1011. Patrap 11:39 PM GMT on September 28, 2010
TROPICAL DEPRESSION SIXTEEN LOCAL STATEMENT NATIONAL WEATHER SERVICE MIAMI FL 653 PM EDT TUE SEP 28 2010 ...TROPICAL DEPRESSION 16 CONTINUES TO HEADS IN THE GENERAL DIRECTION OF SOUTH FLORIDA... .AREAS AFFECTED... THIS LOCAL STATEMENT PROVIDES IMPORTANT INFORMATION AND RECOMMENDED ACTIONS FOR PEOPLE AND MARINE INTERESTS IN SELECT LOCATIONS AND COASTAL WATER LEGS OF SOUTH FLORIDA. Member Since: July 3, 2005 Posts: 372 Comments: 111632

1012. Hurricanes101 11:39 PM GMT on September 28, 2010
Quoting nash28: I'm concerned after the moonwalk and Nicole roll through, Summerville will be Riverville for a few days. If it becomes Mudville then look out for Casey Member Since: March 10, 2010 Posts: 1 Comments: 6902

1013. AnthonyJKenn 11:40 PM GMT on September 28, 2010
Quoting TropicalMan2010: ???huh??? Quoting StormHype: The longer range global models show a monster cold front sweeping into the GOM within a couple weeks.... looks like the fat lady is warming up soon for the 2010 season. Sure...for the Western/ NW Gulf west of the Panhandle, perhaps. With that monsoon trough still in place for another 2-3 weeks, though, Central and South Florida still might be under the gun.....and so is Central America and S Mexico. And Cuba, Hispanola, and Puerto Rico. And I wouldn't rule out a possible major coming up the Eastern Seaboard, either. In short, unless you live in coastal TX, LA, MS, or AL (and perhaps even the western portion of the FL Panhandle, the season is still on until at least the first of November. And even the above mentioned states, while the pattern does look good, should stay on guard for any surprises. Anthony Member Since: September 20, 2005 Posts: 0 Comments: 187

1014. StormHype 11:40 PM GMT on September 28, 2010
Quoting CaptnDan142: Considering the past couple weeks with the GFS long range... Well, I don't think I'll run for Home Depot quite yet. You got that right! Member Since: May 31, 2007 Posts: 0 Comments: 1163

1016. Patrap 11:40 PM GMT on September 28, 2010
Quoting P451: Outflow appears to be coupling better with the low level center. Less shear over the center for certain now. Outflow is much more in line with the disturbance itself. Cuba is the real problem at the moment. A lot of land interaction for this system until it finds itself east of Florida and in the Gulf stream looking towards the Pressolinas. Itsa Big and well..going to affecxt a lotta real estate with a lotta rain. This is the threat to be aware of. Id listen closely to ones NOAA Radio for LOCAL ACTION statements,esp along the coastal regions and in Low-lying areas. Member Since: July 3, 2005 Posts: 372 Comments: 111632

1018. Hoff511 11:41 PM GMT on September 28, 2010
Hey PSL! What do you expect for us? (in PSL) Member Since: September 2, 2009 Posts: 0 Comments: 254

1019. KEEPEROFTHEGATE (Mod) 11:41 PM GMT on September 28, 2010
016L/TD/XX MARK 17.79N/79.79W Member Since: July 15, 2006 Posts: 144 Comments: 40658

1020. CaptnDan142 11:41 PM GMT on September 28, 2010
Quoting Hurricanes101: GFS long range has actually been very good this season I would be weary of it showing a system Uh, OK.... Watching it spit out system after system, running up Florida four at a time, yeah, I guess I am pretty weary of it. Member Since: August 21, 2007 Posts: 0 Comments: 856

1021. MiamiHurricanes09 11:42 PM GMT on September 28, 2010
...CENTER OF THE DEPRESSION RE-FORMS A LITTLE TO THE EAST... SUMMARY OF 800 PM EDT...0000 UTC...INFORMATION ---------------------------------------------- LOCATION...21.4N 82.0W ABOUT 110 MI...175 KM SSE OF HAVANA CUBA ABOUT 325 MI...520 KM SSW OF MIAMI FLORIDA MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/HR PRESENT MOVEMENT...NNE OR 25 DEGREES AT 8 MPH...13 KM/HR MINIMUM CENTRAL PRESSURE...997 MB...29.44 INCHES Member Since: September 2, 2009 Posts: 129 Comments: 19976

1022. Patrap 11:42 PM GMT on September 28, 2010
# VIDEOCAST : Weather Briefing On Expected Impacts From TD,NWS Miami Office Member Since: July 3, 2005 Posts: 372 Comments: 111632

1023. Levi32 11:42 PM GMT on September 28, 2010
Quoting weatherman12345: levi, is this sytem orgainzing right now. thise 80 degree cloudtops have occured during the last hour. It's still disorganized but is a bit better than this morning, and will continue to slowly organize during the next 36-48 hours up until landfall in the Carolinas. Member Since: November 24, 2005 Posts: 587 Comments: 25459

1024. Levi32 11:43 PM GMT on September 28, 2010
Out for now. Member Since: November 24, 2005 Posts: 587 Comments: 25459

1026. presslord 11:44 PM GMT on September 28, 2010
OK Levi...now you're just messin' with me... ; ) Member Since: August 13, 2007 Posts: 0 Comments: 10377

1027. Hurricanes101 11:44 PM GMT on September 28, 2010
Quoting CaptnDan142: Uh, OK.... Watching it spit out system after system, running up Florida four at a time, yeah, I guess I am pretty weary of it. Wow you must have missed what the model said completely, only 1 or 2 runs did that it nailed the development of Matthew and this system in the long range, the other systems it has formed; we are yet to that timeline to see if it varifies Member Since: March 10, 2010 Posts: 1 Comments: 6902

1029. StormFreakyisher 11:44 PM GMT on September 28, 2010
Quoting weatherman12345: sammy, why do you think the schools are waiting so long? I know right?!The more the tracks shift to the left the more likely we will get the heavy rain and wind which is mostly on the east side of this storm so we shoul;dn't have school tomorrow. Member Since: May 16, 2009 Posts: 0 Comments: 684

1030. nash28 11:44 PM GMT on September 28, 2010
Convection still SE of COC. If it wraps before FL landfall, look out. Member Since: July 11, 2005 Posts: 190 Comments: 16972

1031. Stormchaser2007 11:44 PM GMT on September 28, 2010
RAINFALL...THE DEPRESSION IS EXPECTED TO PRODUCE TOTAL RAIN ACCUMULATIONS OF 5 TO 10 INCHES OVER THE CAYMAN ISLANDS... JAMAICA...AND CUBA. ISOLATED MAXIMUM AMOUNTS OF 20 INCHES ARE POSSIBLE OVER THE HIGHER ELEVATIONS OF CUBA AND JAMAICA. THESE RAINS COULD CAUSE LIFE-THREATENING FLASH FLOODS AND MUD SLIDES. RAIN ACCUMULATIONS OF 4 TO 8 INCHES ARE POSSIBLE OVER PORTIONS OF EXTREME SOUTHERN FLORIDA AND THE FLORIDA KEYS. WIND...TROPICAL STORM CONDITIONS WILL BE AFFECTING THE WARNING AREAS IN THE CARIBBEAN TONIGHT...AND SPREAD INTO THE BAHAMAS AND PORTIONS OF SOUTH FLORIDA ON WEDNESDAY. TORNADOES...ISOLATED TORNADOES ARE POSSIBLE OVER SOUTHEASTERN FLORIDA AND THE FLORIDA KEYS THROUGH TONIGHT. Member Since: June 9, 2007 Posts: 4 Comments: 15249

1032. mississippiwx23 11:45 PM GMT on September 28, 2010
And it starts. Thunderstorms here in Mt. Pleasant, SC. Member Since: August 20, 2007 Posts: 3 Comments: 683

1034. Levi32 11:46 PM GMT on September 28, 2010
Quoting presslord: OK Levi...now you're just messin' with me... ; ) Lol :P Quoting weatherman12345: you dont think this will be a storm before a florida landfall though? the forecast calls for it to become a 45 mph storm before landfall. We will probably be seeing TS-force gusts, but we may see a struggle on whether to name it given that most of the strongest winds may not make it onshore to be measured. Member Since: November 24, 2005 Posts: 587 Comments: 25459

1035. Patrap 11:46 PM GMT on September 28, 2010
WFO SWAN 5-panel Models for Miami area Caution,LARGE File Member Since: July 3, 2005 Posts: 372 Comments: 111632

1036. Stormchaser2007 11:47 PM GMT on September 28, 2010
Member Since: June 9, 2007 Posts: 4 Comments: 15249

1037. Seastep 11:47 PM GMT on September 28, 2010
Have a "Mom" report of our HS being closed... unconfirmed. Member Since: September 9, 2008 Posts: 6 Comments: 3406

1038. spathy 11:47 PM GMT on September 28, 2010
FOR MARINE INTERESTS...A TROPICAL STORM WATCH IS IN EFFECT FOR THE GULF WATERS FROM CAPE SABLE TO CHOKOLOSKEE. So thats how you spell Chokoloskee. My spell check does not help. Now if I would only follow instructions on the word Thats! Punctuation is for the unimaginative! Or is it for the overimaginative? Oh well.... Take from it what you will. Folks do that anyway! Member Since: June 8, 2008 Posts: 65 Comments: 10490

1039. Patrap 11:47 PM GMT on September 28, 2010
Member Since: July 3, 2005 Posts: 372 Comments: 111632

1040. Seastep 11:48 PM GMT on September 28, 2010
That's Broward. Off to pick up my daughter. Can you guess? BBL. LOL. Member Since: September 9, 2008 Posts: 6 Comments: 3406

1041. Patrap 11:48 PM GMT on September 28, 2010
Charleston, Base Reflectivity 0.50 Degree Elevation Range 248 NMI Member Since: July 3, 2005 Posts: 372 Comments: 111632

1043. charlestonscnanny 11:48 PM GMT on September 28, 2010
Quoting nash28: I'm concerned after the moonwalk and Nicole roll through, Summerville will be Riverville for a few days. Thanks for the warning, I live in Summerville :) Member Since: August 5, 2010 Posts: 0 Comments: 106

1046. ElConando 11:49 PM GMT on September 28, 2010
Quoting weatherman12345: which one? LOL Member Since: September 6, 2009 Posts: 2 Comments: 3703

1047. myrtle1 11:49 PM GMT on September 28, 2010
press save me alittle rain here in myrtle beach piz! Member Since: June 8, 2008 Posts: 0 Comments: 30

1049. Stormchaser2007 11:50 PM GMT on September 28, 2010
Quoting weatherman12345: which one? LOL You really don't like school. Member Since: June 9, 2007 Posts: 4 Comments: 15249

1051. presslord 11:52 PM GMT on September 28, 2010
it's startin' to roll in from offshore... Member Since: August 13, 2007 Posts: 0 Comments: 10377

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