Caribbean disurbance 96L nearly a depression; hottest day ever in Los Angeles

By: Dr. Jeff Masters , 1:54 PM GMT on September 28, 2010

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Pressures continue to fall over the Western Caribbean this morning as a strong tropical disturbance (96L) organizes. Surface observations suggest that 96L has a large circulation covering most of the Western Caribbean, as evidenced by winds out of the southwest sustained at 29 - 34 mph observed at Buoy 42057 to the southeast of 96L's center this morning. Rotation of 96L 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 are bringing torrential rains to the Cayman Islands, Jamaica, Cuba, and Honduras. A Personal Weather Station in George Town on Grand Cayman Island has picked up 3.64" of rain in the twelve hours ending at 8am this morning. 96L is not the typical sort of disturbance one sees in the Atlantic, since it is much larger than normal. What has happened is that 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). 96L 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 a regular tropical storms, if given enough time over water to develop a tight, closed circulation. The Hurricane Hunters are scheduled to fly into 96L this afternoon near 2pm EDT to see if it has become a tropical depression.


Figure 1. Morning radar image of 96L. Image credit: Cuban Institute of Meteorology.

Forecast for 96L
Because 96L is so large and lacks a well-defined surface circulation, it will take more time than a typical disturbance for it to spin up into a strong tropical storm. Given that the steering currents are expected to pull 96L 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 55 mph tropical storm for Florida. I think the top winds in Southeast Florida are likely to be in the 30 - 45 mph range on Wednesday. By the time 96L makes landfall in North Carolina or South Carolina on Thursday morning or afternoon, it could be as strong as a 55 - 65 mph tropical storm, but I think it is only 20% likely that 96L will make it to hurricane strength on Thursday. The primary danger from the storm is heavy rainfall. A potent upper-level low and stationary front over the U.S. East Coast have been bringing moist, tropical air from the Caribbean northwards over the past few days, bringing heavy rains that have saturated the soils. 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 96L 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.


Figure 2. Radar-estimated precipitation since Saturday for the North Carolina/South Carolina border region. Widespread rain amounts of 5 - 10 inches have occurred.


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

Elsewhere in the tropics
Once 96L 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 late this week or early next week. The other models are not showing this, but do predict a continuation of the disturbed weather pattern over the Western Caribbean. A second disturbance, if it develops, would be subject to similar steering currents, and may also move northwards across Cuba, Florida, and the Bahamas, then up the U.S. East Coast. This second disturbance might be more dangerous, since it would be dumping heavy rains on regions already drenched by 96L.

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 Beverly Hills 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 96L requires.

Jeff Masters

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TROPICAL DEPRESSION SIXTEEN LOCAL STATEMENT
NATIONAL WEATHER SERVICE KEY WEST FL
1228 PM EDT TUE SEP 28 2010

...TROPICAL DEPRESSION SIXTEEN FORMS ABOUT 280 MILES SOUTH SOUTHWEST
OF KEY WEST...

.AREAS AFFECTED...
THIS LOCAL STATEMENT PROVIDES IMPORTANT INFORMATION AND
RECOMMENDED ACTIONS FOR PEOPLE AND MARINERS IN THE FLORIDA KEYS
OF MONROE COUNTY AND ADJACENT COASTAL WATERS.

.WATCHES/WARNINGS...
A TROPICAL STORM WARNING IS IN EFFECT FOR THE FOLLOWING
LOCATIONS...MONROE UPPER KEYS...MONROE MIDDLE KEYS AND MONROE
LOWER KEYS.

FOR MARINE INTERESTS...A TROPICAL STORM WARNING IS IN EFFECT FOR
ALL OF FLORIDA KEYS COASTAL WATERS.

.STORM INFORMATION...
AT 12 PM EDT...THE CENTER OF TROPICAL DEPRESSION SIXTEEN WAS
LOCATED NEAR LATITUDE 20.6N...LONGITUDE 82.5W. THIS WAS ABOUT
280 MILES SOUTH OF KEY WEST FL. MAXIMUM SUSTAINED WINDS WERE NEAR 30
MPH.

.SITUATION OVERVIEW...
TROPICAL DEPRESSION SIXTEEN ABOUT 280 MILES SOUTH TO SOUTHWEST OF KEY WEST
FLORIDA WILL MOVE SLOWLY NORTH NORTHEAST ACROSS CENTRAL CUBA AND POSSIBLY
BECOME A MINIMAL TROPICAL STORM. ITS EXPECTED TO MOVE NORTH NORTHEAST AND
APPROACH THE UPPER KEYS WEDNESDAY AFTERNOON...WITH THE BULK OF THE STRONG
WINDS AND HEAVY RAIN TO THE EAST OF THE FLORIDA KEYS.

.NEW INFORMATION...
UPDATED LOCATION OF NEWLY FORMED TROPICAL DEPRESSION SIXTEEN.
TROPICAL STORM WARNING IN EFFECT FOR ALL THE FLORIDA KEYS AND THE
ADJACENT COASTAL WATERS.

.WINDS...
OUTSIDE OF SHOWERS AND THUNDERSTORMS...EAST WINDS OF AROUND 15 MPH WILL
INCREASE TO BETWEEN 15 AND 20 MPH TONIGHT AND PER PAPS NEAR 20 MPH ON
WEDNESDAY.

.RAINFALL IMPACTS...
OVER THE NEXT 24 TO 36 HOURS...RAINFALL AMOUNTS WILL RANGE FROM 1 TO
3 INCHES WITH LOCALLY HIGHER AMOUNTS POSSIBLE IN THE UPPER KEYS.


.MARINE IMPACTS...
OUTSIDE OF SHOWERS AND THUNDERSTORMS...SUSTAINED TROPICAL STORM FORCE WINDS
ARE NOT EXPECTED.

.PRECAUTIONARY/PREPAREDNESS ACTIONS...
PRECAUTIONARY/PREPAREDNESS ACTIONS...
DUE TO WEAK AND DISORGANIZED TROPICAL SYSTEM...ALL PEOPLE IN THE
FLORIDA KEYS SHOULD MONITOR THE PROGRESS OF THIS SYSTEM.

&&

.NEXT UPDATE...
THE NEXT LOCAL STATEMENT CONCERNING THE IMPACTS OF TROPICAL
DEPRESSION SIXTEEN TO THE FLORIDA KEYS WILL BE ISSUED BY THE
NATIONAL WEATHER SERVICE IN KEY WEST BY 3 PM...OR SOONER IF NEW
INFORMATION BECOMES AVAILABLE.

GMZ031>033-052>054-072>075-282230-
/O.NEW.KKEY.TR.W.0002.100928T1628Z-000000T0000Z/
FLORIDA BAY-GULF SIDE OF THE LOWER KEYS OUT 20 NM-
GULF WATERS FROM EAST CAPE SABLE TO CHOKOLOSKEE 20 TO 60 NM OUT-
OCEAN REEF TO CRAIG KEY OUT 20 NM-
CRAIG KEY TO THE WEST END OF THE 7 MILE BRIDGE OUT 20 NM-
WEST END OF THE 7 MILE BRIDGE TO KEY WEST OUT 20 NM-
OCEAN REEF TO CRAIG KEY 20 TO 60 NM OUT-
CRAIG KEY TO THE WEST END OF THE 7 MILE BRIDGE 20 TO 60 NM OUT-
WEST END OF THE 7 MILE BRIDGE TO KEY WEST 20 TO 60 NM OUT-
KEY WEST TO 20 NM WEST OF DRY TORTUGAS OUT 60 NM-
1228 PM EDT TUE SEP 28 2010

...TROPICAL STORM WARNING IN EFFECT...

...NEW INFORMATION...
UPDATED LOCATION OF NEWLY FORMED TROPICAL DEPRESSION SIXTEEN.
TROPICAL STORM WARNING IN EFFECT FOR ALL THE FLORIDA KEYS AND THE
ADJACENT COASTAL WATERS.

...PRECAUTIONARY/PREPAREDNESS ACTIONS...
PRECAUTIONARY/PREPAREDNESS ACTIONS...
DUE TO WEAK AND DISORGANIZED TROPICAL SYSTEM...ALL PEOPLE IN THE
FLORIDA KEYS SHOULD JUST MONITOR THE PROGRESS OF THIS SYSTEM.

&&

...WINDS AND SEAS...
AS TROPICAL DEPRESSION SIXTEEN APPROACHES...EAST WINDS OF 15 TO 20
KNOTS SHOULD INCREASE TO NEAR 20 KNOTS LATE TONIGHT AND TONIGHT ON
WEDNESDAY. HOWEVER...WINDS AND SEAS WILL BE LOCALLY HIGHER IN AND
NEAR SHOWERS AND THUNDERSTORMS.
Member Since: Posts: Comments:
thanks
Member Since: June 8, 2008 Posts: 0 Comments: 30
Quoting catastropheadjuster:
Has the site crashed or something. I know everyone didn't leave.
sheri


Sheri

The only one who got hurt was the bonehead with the weapon.... He got himself and no one else.
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Looking at the CMC and about 72 hours the remnants of matthew reforms...will it be otto or matthew?

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TD 16 looks less organized, shear is doing a number on it.

Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting pottery:

That's not too bad for now. But as you say, conditions look to be deteriorating soon.
Keep us posted.


Will do
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Quoting FLHurricaneHunter:
"official" word from American Heritage is that they are keeping school open today and will most likely make decision for tomorrow around 3pm today... but for now it is status quo there (Plantation, Florida - Broward county).

Now to go and hunt down wife for slightly "incorrect" info... my apologies.


Great school I want my son to go there
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Big line of t-storms moving into Ft. Myers. Very dark to the southeast.
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'sposed to do sea trial on a new boat Thursday...Think maybe we oughta reschedule?!
Member Since: August 13, 2007 Posts: 0 Comments: 10492
recon about an hour out. wonder if cuba game them an ok to fly over there air space. will have to watch the flight path. but i thonk they may have
Quoting myrtle1:
nash do you think we will get some bad weather up here in myrtle beach


Well, depends on exact track and whether or not the west side of this is dry as a bone.. If this tracks further to the west as depicted by the 12z GFS then yeah. We'll all get hammered.
Member Since: July 11, 2005 Posts: 190 Comments: 16972
Quoting kmanislander:


Not too bad at the moment. I am on the 4th floor of a CAT 5 rated office building that sits about 150 feet from the seashore by the harbour. Swells look to be running at about 4 feet but no overwash on the road.Relatively calm actually. Visibility now about 3 miles with light rain but that looks set to change soon.

That's not too bad for now. But as you say, conditions look to be deteriorating soon.
Keep us posted.
Member Since: October 24, 2005 Posts: 0 Comments: 24390
Link

This is the GFDL model analysis that looks the best to me.... pretty what Patrap displayed
Member Since: July 17, 2005 Posts: 0 Comments: 1025
This storm will be much stronger wind wise for the Carolina,s than for Florida. In fact it may bomb out off of New England if it is a true hybrid system...Did I type Carolina,s correctly? So clumsy I must be blind...
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this TD16 will put an end to the season. gonna pull that cooler drier air down to us!!! wooo hoooooooo!!!
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Quoting catastropheadjuster:
Has the site crashed or something. I know everyone didn't leave.
sheri
I had the same problem..blog slowed down to nothing as if everyone left.
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Quoting pottery:

Looks threatening as all heck there Kman...
How are the sea conditions?


Not too bad at the moment. I am on the 4th floor of a CAT 5 rated office building that sits about 150 feet from the seashore by the harbour. Swells look to be running at about 4 feet but no overwash on the road.Relatively calm actually. Visibility now about 3 miles with light rain but that looks set to change soon.
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Link


Ocean cam on NC coast should be interesting thursday.
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Has the site crashed or something. I know everyone didn't leave.
sheri
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nash do you think we will get some bad weather up here in myrtle beach
Member Since: June 8, 2008 Posts: 0 Comments: 30
Yeah.. You can blame me:-)

We needed the rain.. Just not all at once!
Member Since: July 11, 2005 Posts: 190 Comments: 16972
Quoting kmanislander:
Very nasty squall line about 30 miles SW of Grand Cayman and closing fast.


Looks threatening as all heck there Kman...
How are the sea conditions?
Member Since: October 24, 2005 Posts: 0 Comments: 24390
Tropical Depression #16 Forms NW of Cayman

Key Message:
At 10:00 a.m. this morning the National Hurricane Center in Miami started issuing bulletins on Tropical Depression #16 which is located at 20.6N 82.5W or about 116 miles NW of Grand Cayman. The depression is moving NNE at 10 mph with maximum sustained winds of 35 mph.

GOVERNMENT HAS ISSUED A TROPICAL STORM WARNING FOR THE CAYMAN ISLANDS.

The Cayman area can expect overcast rainy weather with periods of heavy torrential rainfall. Rainfall models predict that another 3 to 4 inches are likely to fall during the next 24 hours.

Strong southwesterly winds and rough seas are expected to continue over our area especially along the south and west coast. Higher gusts up to tropical storm force are expected in squally conditions in and around heavy showers.

The CI National Weather Service will continue to monitor the progress of this system.

Advice to local population:
All marine craft should seek safe habour and remain there until further notice.

Flooding of low lying areas is expected and residents should take necessary precautions.

Residents are urged to stay tuned to the local media for further updates.

Further information:
The next bulletin will be issued 4 p.m. today.



________________________________________
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468. JLPR2
Well I'm off, later everyone!
And behave... XD
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Quoting cat5hurricane:
This map doesn't tell complete story. There's been local reports of 7-10 inches in SC. Any more rain is just going to aggravate the flooding potential.



it's nash's fault...he was in here Sunday complaining about our lack of rain...
Member Since: August 13, 2007 Posts: 0 Comments: 10492
But I can tell you we here in the Charleston area DO NOT need nor want 5-8" of additional rainfall. No thank you.
Member Since: July 11, 2005 Posts: 190 Comments: 16972
Very nasty squall line about 30 miles SW of Grand Cayman and closing fast. This image 15 minutes old.

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if this cyclone stays over water for tonight.. it could become a very strong system..

it's organizing its circulation right now.. which is why there isn't much convection near the center, that and some light shear blowing over the center.

Tonight though could be MONSTROUS, it's over VERY VERY HOT WATERS, that can fuel a wilma. It's almost impossible for it to become a wilma, but it's probable that if it's still over water tonight, it could strengthen into a much stronger system than forecasted
Member Since: April 17, 2010 Posts: 0 Comments: 1753
We're talking less than three days away (for the Carolina impacts.) I do not expect any major changes in track, other than a shift to the left which puts Charleston in the cross hairs, or shift slightly to the east which keep the center offshore. That's about it.

I know StSimons needs the rain in the worst way. Makes me wanna "wishcast" Nicole even further W so he can get some relief.
Member Since: July 11, 2005 Posts: 190 Comments: 16972
did the blog die?
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Quoting immaturehurjunkie:
Funny stuff!

Link


Okay, that is funny. :)
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460. JRRP
Quoting JLPR2:


Yeah, looking slightly better today.

at least yellow code the next TWO
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459. JLPR2
TD 16 is huge, that should slow its development a bit.
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Estero, FL 29.71 and falling...
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It might get a little hotter so chill
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454. JLPR2
I bet this was posted already but...

28/1145 UTC 21.0N 82.8W ST1.5 96L

Subtropical classification T#
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Sorry this is off the subject, has anyone heard about a shooting at a University in Texas it was on a TV in a business I went in to, but didn't catch it all. I really hope no one was hurt.
sheri
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Quoting nash28:


I am in the same region as Press and would be happy and willing to assist my time.


Roger dat nash,..we will notify you if we deploy to a specific region
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Quoting CaptDanny:
Preasure is 1008 in Ruskin Fl. Down from 1010 12 hours ago

I'm down to 1008 and steady now, too. (Spring Hill/Brooksville area).
Member Since: August 18, 2008 Posts: 0 Comments: 884
I know that the ground is saturated and will not help the situation
Member Since: July 17, 2005 Posts: 0 Comments: 1025
Does the "strength" of a trough having anything to do with how "strong" ridge will build back in? TIA
Member Since: July 6, 2010 Posts: 0 Comments: 50
447. JLPR2
Quoting JRRP:


Yeah, looking slightly better today.
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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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