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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How does the 5-gallon bucket work to measure rain?
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Good morning,

I'm just saying that with whatever happens to TD16/Nicole, there is going to be a LOT of moisture left over in the Carib with very low pressures , and the wave out in the CATL will only help to lower the pressure and bring more moisture, at least.
Something has got to give. I do think that TD 16 will eventually become Nicole, eventually.

It's been raining here in West Palm non stop for a ver very long time.
I don't know how much, but it has been very rainy.

The Carib is going to be very active for a while.
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Quoting jasoniscoolman2010xo:



looking better this morning.


I agree, it has organized well overnight with deep convection surrounding the center.
Member Since: July 1, 2008 Posts: 13 Comments: 7340
2482. 7544
ok if thats the center then conv is building on the west side now and still 200 + miles from so fla looks like its trying to organize a little better at this hour
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I finally figured out what storm this reminds me of. Tropical storm tammy from 2005. It had the huge plume of covection from the pacific to North Caroilina. Also the winds where very spread out. I remember them talking about Tropical force winds in South Carolina while it was making landfall in Florida.
TD 16 is not subtropical. It is simply a very broad tropical depression/possible tropical storm (monsoon) interacting with a frontal zone. Of course its not going to look tropical outside in The Carolinas. That is the front that went through yesterday retrograting back through.
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Quoting cat5hurricane:
Since before this recent downpour from the latest squall still going on, I only had slighly more than you. I was very pleased waking up to see that...but I know it's just the calm before the storm.

It's coming down gang-busters here now in Isle of Palms...so that cluster will be in & around Monks corner (lake moultrie watershed) in a few hrs.

I'm still preparing for the worst but hopin' for the best though!!


Yep, can see the red and orange waxing a bit larger and deeper in color, strolling towards us, whistling, hands in pockets. Should start here in about half an hour.

Finally got smart this morning, dug out a remote-op thingie for outdoor Christmas lights, plugged it in, and hooked up two sump pumps to it. Now all I have to do is go to the window and click to turn the pumps on and off. Yesss!
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Quoting reedzone:
Photobucket


You are right!
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HPC 12Z surface map

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LPS reforming SW of Isle of Youth?
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LOL!!!

I hear ya, but I'm a speed limit driver, so it wasn't me!
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Photobucket
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2471. MZT
Cool, damp morning here in NC. That's how it feels when a barocyclonic low is coming up the coast. Not breezy and cirrus-y, from the outflow of a warm core system.

NHC is saying this system has a "narrow window of time" to be named. I say 60/40 it won't be.
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May I come to grand cayman just to see how is the weather there :) :) so bored here at 18N63W!
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Quoting leelee75k:
Why do people drive 10mph in light rain?
More danger from bad drivers today than there is from TD16 in South Florida.

they only look like they are going 10mph to the people going 90 with their flashers on ;)
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Well finally,  it's now looking & feeling like monsoon type conditions here on Key Vaca.  Heavy rain, coming straight down, light wind. Nearly calm seas.  I like it, for at least the rest of the day since it will fill up the cisterns, my water supply for irrigation during the winter.  


   
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2467. A4Guy
Quoting IKE:
TWC showing the opening bell on Wall Street. Why? What happened to...The Weather Channel? If I want business news I'll switch to CNBC.


lol - what happened is that NBC bought TWC...so they "cross pollenate" all their channels now. That's also why we have to "Wake Up With Al" too.
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Quoting reedzone:
Convection is too deep for it to be Extratropical. Eventually, I think the NHC will give up and name this soon.

...if it gets named it will be subtropical, matt....the sat presentation even looks. like its transitioning and leavING A west- east orientd trough behind from yucatan area to hispaniola imo
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Quoting reedzone:
If TD16 relocated near the convection, where there is bands and deep storms? What's the NHC smoking? This is a Tropical Storm..


Oh please - this thing has had centers all over the place. Its essentially a broad area of low pressure with a 300 mile center of equal pressure (997-998mb). The pressure 150 miles SE of the center and 200 miles SW of the center is nearly equal. Its essentially what the some of the models predicted, an elongated area of low pressure. my gut is this will eventually pull out with overall low pressure remaining to form something else in the days ahead. You probably feel the same way.
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weather.com is dropping my rain chances to 25/30% by early afternoon... are they seeing something that I don't?
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2460. IKE
TWC showing the opening bell on Wall Street. Why? What happened to...The Weather Channel? If I want business news I'll switch to CNBC.
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Why do people drive 10mph in light rain?
More danger from bad drivers today than there is from TD16 in South Florida.
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Quoting stormpetrol:
We now have a due west wind in Grand Cayman sustained at 28mph.
Sounds like you have a cold front coming through...except you are REALLY far south for that..
should clear out soon though.
I swear this thing is a huge hybrid storm with such mixed characteristics to be undefinable although everyone wants to.
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Quoting reedzone:
Convection is too deep for it to be Extratropical. Eventually, I think the NHC will give up and name this soon.



Convection too deep from a tropical origin?...Hmmm.
Even *if* they name her, it's a mutt point as this wilol be only a rain maker as it develops a new surface low along the baroclinic boundary off the coast of Ga/Sc this afternoon.
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Quoting presslord:


What are the next 36 hours gonna look like, mon?


Morning Press, sleeping off that hangover after a night of boozing at Henry's. Anyway, bit of a lull in the precip right now. Starting to fill in now. Evening drive is going to be a mess. Heaviest rain should fall from noon - late tonight, then taper quickly by tomorrow morning. Looks like rain bulls-eye now in myrtle beach and eastern NC. Still should get 3-4 inches in Charleston, good news is that low tide is at 6:57 pm.
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Quoting Orcasystems:


To name it.. they have to find it... I don't think they have actually found it yet?


If you look at the satellite, I think the actual center is a tad south of where they have relocated it, but they're getting closer :P
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2453. bwi
This line from the NWS Baltimore/Washington DC (LWX) morning discussion caught my eye -- sums up our weather year pretty well so far:

NEAR TERM /UNTIL 6 PM THIS EVENING/...
I`LL SAY THIS - THE WX OF 2010 IS SOMETHING I WON`T SOON FORGET.
BLIZZARDS..SVR TSTMS..RECORD BRKG HEAT..DROUGHT..AND NOW PTNL
FLDG.
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Quoting surfmom:
same here - can't beleive I have to water the veggies -- course once I do the rain will happen... never fails
....sorry about the wavez i kinda/sorta promised u :(.......maybe will still get a tc his year(yea right!!)....havent had anything even close to a tc threaten our area since i moved to the key,we need the rain locally and am going to have to water the pepper and strawberry plats myself!!!
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Link
Live feed of weather at Owen Roberts airport, GRand Cayman
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Quoting Bobbyweather:

I see TD 16 on the bottom left.
Possibly the remnants of Julia becoming organized? (Or maybe I dislocated it, and it dissipated)

Julias Low Level remains are NW of Bermuda and the circulation is finally almost gone. The feature you are looking at separated off at about 30W several days ago. Looks like a small mid upper level low .
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2449. MZT
Quoting Chucktown:


No its not - no wind, too broad. Becoming extra tropical as we speak and will redevelop along the baroclinic boundary off the coast of SC. Its a nor'easter, but starting out in the Caribbean.
Yeah, I thought similarly yesterday night. This does not have a tropical appearance and the strongest winds will be well to the east.
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Quoting reedzone:
Convection is too deep for it to be Extratropical. Eventually, I think the NHC will give up and name this soon.



To name it.. they have to find it... I don't think they have actually found it yet?
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Quoting Bobbyweather:

I see TD 16 on the bottom left.
Possibly the remnants of Julia becoming organized? (Or maybe I dislocated it, and it dissipated)


I was wondering too about that little swirl on the right .... Hey,got sunshine here in NW Orlando ... rain to come?
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Quoting cat5hurricane:
It came down like hell for a while in Isle of Palms, SC last nite. Sorta a break in the action in and around the Charleston area...but that will likely change very soon.

The 5 gallon bucket has been ready to go now for some time. Hopefully the totals won't be as high as some of the HPC precip forecasts were yesterday.

Plus it appears that TD 16 is a bit weaker than what was anticipated yesterday.>


My 5-gallon bucket shows only 1/2" from last night. Thought there would be more--but I'm a bit further from the coast than most of you South Carolinians.
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Quoting CyclonicVoyage:


That wedge of dry air is advancing rather steadily to the west of FL, almost over the peninsula now.


Slow movement and pulling moisture up from the Caribbean.
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Convection is too deep for it to be Extratropical. Eventually, I think the NHC will give up and name this soon.

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Quoting surfmom:
same here - can't beleive I have to water the veggies -- course once I do the rain will happen... never fails


Remember you said that :)
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We now have a due west wind in Grand Cayman sustained at 28mph.
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Quoting Chucktown:


No its not - no wind, too broad. Becoming extra tropical as we speak and will redevelop along the baroclinic boundary off the coast of SC. Its a nor'easter, but starting out in the Caribbean.


What are the next 36 hours gonna look like, mon?
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Member Since: July 1, 2008 Posts: 13 Comments: 7340
2438. surfmom
Quoting BobinTampa:


Tampa is still pitching a virtual shutout. Haven't gotten much at all.
same here - can't beleive I have to water the veggies -- course once I do the rain will happen... never fails
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2436. WxLogic
Quoting GaleWeathers:
Hi all, long time lurker and part time hurricane season poster here. I'm wondering if someone could please direct me to a link showing rainfall amounts over the last x hours? I'm down here in South Florida, and I've heard that my area has had the most rainfall so far. I'd like to know what we're up to and what to expect.

Thanks in advance for any replies. Stay safe and dry out there fellow Floridians :D



Radar Link


Check the 1HR and Storm Total on the Left pane
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2435. 7544
center may be more south on the next update
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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.

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