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

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

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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.
Alone again, naturally

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2235. surfmom
2218 - love those Aerial pics CAT5 : )
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2234. WxLogic
One thing is for sure... Jamaica is getting owned.
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Link

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2232. Patrap
Member Since: July 3, 2005 Posts: 423 Comments: 127810
2231. Grothar
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Good morning everyone. Well, still coming down in buckets and gusty winds. Power went off in East End last night around 10:00 and just came back on about 15 minutes ago. Looks like another nasty day.
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2229. surfmom
NW CARIB - AHA!!!!! -Kman - got my attention 1,2,3
this AM

Still curious about the measurement discrepancies you mentioned last night - Yes, I woke up with that on my mind - is it a matter of calibration & when maps are shown w/ wrong inform -- does that only affect the amateur - are there repercussions or was the difference too small to matter
(Only if you have time)
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Wind in the 30s now. Just saw 36 mph
Member Since: August 19, 2006 Posts: 0 Comments: 15807
Quoting Saltydogbwi1:


couldnt believe the pressure reading this morning had to take another slug of coffee and look again but your reading confirms mine! lol I agree with you on the possibility of something trying to get going in the neibourhood.

wow and as if to prove a point, a branch on a tree outside my house has just blown off. Lashing down and very gusty!!
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2226. srada
Good Morning

Just saw Bill Reed on TWC and he said that TD16 will strength to TS strength after exiting Florida..the Carolinas are looking at real bad conditions for the next couple of days..Its pouring here in wilmington from the first low pressure and now we are going to get smack with a TS right behind it..Flash Flood Warning already issue here..12 inches of rain so far since Monday
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2225. Grothar
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Quoting Becca36:
Good morning all. Just coming out of lurking for a bit. Here in West Boca we just have had lots of heavy rain but no wind to speak of yet. I'm not surprised that all the schools are open, I just hope the wind doesn't reach the magic 40mph number for the school buses later this afternoon.


West Boca as well... not getting any wind hardly at all... they keep saying it should pick up a bit later... I was a little surprised about the schools too... already saw some flooding on TV here in town.
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Quoting TampaSpin:


Models have been saying that all week KMan. If that happens and i talked about that on my blog that it could be a more Westerly moving system as High Pressure builds back in behind TD16


It is pretty wild outside now. The wind is gusting to 27 mph and torrential rain !
Member Since: August 19, 2006 Posts: 0 Comments: 15807
I think 16L tropical depression, tropical storm is worth because the reconnaissance flight entered tropical storm winds of 35 kt.
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Quoting hunkerdown:
Palm Beach County here...i just don't see those the lines coming down from winds in the 10mph category (and I don't see any reports from the Keys up with any winds to speak of).


Yep, i agree that our Afternoon Thunderstorms might be stronger than this. I know some thought school should have been called off. That does not need to happen either IMO.
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3 days out



4 days out

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Quoting kmanislander:
Good morning everyone

The Caribbean has a decidedly nasty look to it this morning and the pressure now is 996.3 mbs, much lower than yesterday when TD 16 was in this neighbourhood.

Another system may be trying to organize in the NW Caribbean IMO


Morning Kman I couldnt believe the pressure reading this morning had to take another slug of coffee and look again but your reading confirms mine! lol I agree with you on the possibility of something trying to get going in the neighbourhood.
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Hey guys what I still don't get i8s that the pressures are reading 995.1mbs and falling wind have been blowing at a good speed gusting higher at times the waves are higher and very murky and right now pouring rain
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Quoting caymanlurker:

Morning Kman; agree with you. Strange, no named storm, yet it is difficult to take your eyes off this area these last 36 hrs. Plenty more rain today and all my children are concerned about is whether the weather will mean Prep closes early again! LOL


LOL. My daughter was doing the rain dance last night and it appears to have worked !
Member Since: August 19, 2006 Posts: 0 Comments: 15807
Quoting kmanislander:
Good morning everyone

The Caribbean has a decidedly nasty look to it this morning and the pressure now is 996.3 mbs, much lower than yesterday when TD 16 was in this neighbourhood.

Another system may be trying to organize in the NW Caribbean IMO


Models have been saying that all week KMan. If that happens and i talked about that on my blog that it could be a more Westerly moving system as High Pressure builds back in behind TD16
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Quoting TampaSpin:
On one serious note for those East Coast Florida people. Still take this serious as you still could loose power from down lines. I know in Tampa i lost power for 4 freaking days in 2004 from downgraded Hurricanes that was slight stronger than this. Lose of power is no fun for that extended period of time. TRUST ME!
Palm Beach County here...i just don't see those the lines coming down from winds in the 10mph category (and I don't see any reports from the Keys up with any winds to speak of).
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Quoting kmanislander:
Good morning everyone

The Caribbean has a decidedly nasty look to it this morning and the pressure now is 996.3 mbs, much lower than yesterday when TD 16 was in this neighbourhood.

Another system may be trying to organize in the NW Caribbean IMO

Morning Kman; agree with you. Strange, no named storm, yet it is difficult to take your eyes off this area these last 36 hrs. Plenty more rain today and all my children are concerned about is whether the weather will mean Prep closes early again! LOL
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Quoting Saltydogbwi1:


pressures here in grand cayman this morning 995.9mb and falling!


yeah. The Little Cayman buoy has 996.3 and I have the same in South Sound. Something else getting going it seems. South wind @20 mph
Member Since: August 19, 2006 Posts: 0 Comments: 15807
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Quoting HCW:


Couple of hours over the Gulf Stream could quickly change things
Quoting islander101010:
agree dont underestimate nature


NOPE....won't make that big of differnce IMO.....not when you got 25-30kts of Shear....i don't see anyway this develops into Nicole and even if NHC does upgrade if before it moves into Florida it will be at the very mininumal strenght IMO.

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Quoting WxLogic:
Interesting enough not sure why NHC says:

...CENTER OF THE DEPRESSION EMERGING OVER THE FLORIDA STRAIT...HEAVY RAINS SPREADING ACROSS FLORIDA KEYS AND SOUTH FLORIDA...

Based on SFC obs... the center of this TD appears to be further S, I've marked the spot on the chart below:



pressures here in grand cayman this morning 995.9mb and falling!
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Good morning everyone

The Caribbean has a decidedly nasty look to it this morning and the pressure now is 996.3 mbs, much lower than yesterday when TD 16 was in this neighbourhood.

Another system may be trying to organize in the NW Caribbean IMO
Member Since: August 19, 2006 Posts: 0 Comments: 15807
2205. HCW
Quoting JupiterFL:


My grass is going to be green next week!


If I paypal you some money can you send some of that much needed rain to South AL ? Only .33 in the last 49 days
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On one serious note for those East Coast Florida people. Still take this serious as you still could loose power from down lines. I know in Tampa i lost power for 4 freaking days in 2004 from downgraded Hurricanes that was slight stronger than this. Lose of power is no fun for that extended period of time. TRUST ME!
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Off to teach my little angels. Have a wonderful Wednesday everyone!
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Quoting HCW:
3.77 inches of rain since midnight reported by a storm spotter in Jupiter,FL


My grass is going to be green next week!
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2200. Becca36
Good morning all. Just coming out of lurking for a bit. Here in West Boca we just have had lots of heavy rain but no wind to speak of yet. I'm not surprised that all the schools are open, I just hope the wind doesn't reach the magic 40mph number for the school buses later this afternoon.
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Quoting HCW:


Couple of hours over the Gulf Stream could quickly change things
agree dont underestimate nature surprised no waterspots have been reported in florida yet
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Quoting connie1976:



I don't even see it becoming much when it goes to South Carolina...


It will be stronger as it approaches South Carolina as a Sub-Tropical system because the wind field will expand out IMO! Hi Connie!
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2196. aimetti
The front alone is going to be a pretty big rain event. so im sure there will be something in SC.
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I see NHC did move the track more inland over Florida and i really don't think it will really make that big of differnce on the track at this point. If td16 does not become Nicole over Cuba "which it won't with the mountians" i really don't think it will become Nicole. NHC might upgrade it to Nicole even if they find a wind gust into TS status.
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2194. HCW
Quoting hunkerdown:
merging with the front will have greater effects


Still could easily get the tag Subtropical Storm Nicole
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2193. HCW
3.77 inches of rain since midnight reported by a storm spotter in Jupiter,FL
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Quoting HCW:


Couple of hours over the Gulf Stream could quickly change things
merging with the front will have greater effects
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2191. HCW
Quoting connie1976:



I don't even see it becoming much when it goes to South Carolina...


Couple of hours over the Gulf Stream could quickly change things
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Quoting TampaSpin:
Good early morning to everyone. Dang i can't believe Florida is not gonna get hit by a major hurricane Nicole. LOL...just kidding of course. At this point i really don't see TD16 becoming very strong. Heck it might not even make it to the Name Nicole at this point until after it becomes Sub-tropical heading toward South Carolina.


I don't even see it becoming much when it goes to South Carolina...
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Just looks like a bunch of rain being funneled north..... I wonder if my neighbors at the end of the streeet are goin to flood since they tend to flood so easily...
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Good early morning to everyone. Dang i can't believe Florida is not gonna get hit by a major hurricane Nicole. LOL...just kidding of course. At this point i really don't see TD16 becoming very strong. Heck it might not even make it to the Name Nicole at this point until after it becomes Sub-tropical heading toward South Carolina.
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Quoting WxLogic:


Well... not circulation wise. A disturbance can still close (becoming a Low or TD or may be a TS) but what the dry air will do is to disrupt convective development which further impedes intensification. In this case you have 2 variables... 1)Shear (15KTS to 25KTS from the SW) and 2) Dry air on the W.

Gotcha. shear chops it, and of course the dry air doesn't offer any fuel for convection. Learned one thing today... thanks.
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called my brother on the mainland he could not believe they are on. school as usual in florida. if i was in charge i would of canceled the day
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2185. HCW
Meso Disco just out

MESOSCALE DISCUSSION 1904
NWS STORM PREDICTION CENTER NORMAN OK
0600 AM CDT WED SEP 29 2010

AREAS AFFECTED...PORTIONS SE FL.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 291100Z - 291330Z

TORNADO POTENTIAL...THOUGH BRIEF/MRGL AT FIRST...MAY BEGIN TO AFFECT
NEAR-COAST AREAS FROM UPPER KEYS TO PALM BEACH COUNTY DURING NEXT
FEW HOURS...SLOWLY SHIFTING INLAND TO INCLUDE METRO CORRIDOR FROM
HST-PBI.

MIA VWP HODOGRAPHS HAVE BEEN SMALL...BUT STEADILY INCREASING IN SIZE
AND IN CURVATURE DURING PAST COUPLE OF HOURS AS CENTER OF TD 16
BEGAN CROSSING FL STRAITS BETWEEN CUBA AND KEYS. WEAKER HODOGRAPHS
HAVE BEEN EVIDENT IN OBSERVED VWP AND MODEL FCST SOUNDINGS WITH WWD
EXTENT THROUGH KEYS...CONCURRENT WITH MORE NEBULOUS/WEAKER
CONVECTIVE STRUCTURES. THIS TENDENCY SHOULD CONTINUE...REDUCING
TORNADO THREAT FROM N THROUGH NW OF CENTER. FURTHER STRENGTHENING
OF BOUNDARY-LAYER SHEAR IS EXPECTED NE OF CENTER ALONG SERN FL COAST
AND UPPER KEYS AS LOW-LEVEL FLOW INTENSIFIES SLIGHTLY OVER ERN
SEMICIRCLE OF SYSTEM...ESPECIALLY IF IT BUILDS TO TS STRENGTH PER
NHC FCSTS. OVERNIGHT RADAR DATA HAVE SHOWN OCNL TSTM-SCALE
CIRCULATIONS OFFSHORE WITH MOST PERSISTENT/DEEPEST ECHOES...ALSO
INDICATING THAT GREATER SRH IS IN PLACE OFFSHORE. SO IS GREATEST
BUOYANCY...MLCAPE ESTIMATED 1000-1500 J/KG OVER WATER...OWING TO
RELATIVELY MAXIMIZED THETAE THAT IS RELATED TO MARINE HEAT FLUXES
OFF GULF STREAM. STRENGTHENING SELY SFC WINDS WOULD ADVECT MORE OF
THIS AIR MASS AT LEAST A FEW MILES INLAND...PERHAPS ACROSS MUCH OF
MIAMI-DADE/BROWARD/PALM BEACH COUNTIES WITH TIME. MEANWHILE 0-1 KM
SRH 150-200 J/KG SHOULD OVERSPREAD GREATER MERIDIONAL EXTENT OF
COASTLINE AS FLOW JUST OFF SFC INTENSIFIES.


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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.