Tropical Depression Fifteen forms in the Caribbean

By: Dr. Jeff Masters , 7:32 PM GMT on September 23, 2010

Tropical Depression Fifteen is here, and is destined to become Tropical Storm Matthew by late this afternoon or this evening. An Air Force hurricane hunter aircraft left the storm near 2pm EDT this afternoon, and on their final pass through the strong northeast quadrant of the storm, found a substantial area of surface winds of 40 - 45 mph with their SFMR instrument. Top flight level winds at 500 feet were 48 mph. These winds support upgrading TD 15 to Tropical Storm Matthew. Satellite loops show that TD 15's heavy thunderstorm activity continues to increase in intensity and areal coverage, with several respectable low-level spiral bands in evidence. There is some dry air to the northwest of TD 15, but it is currently not significantly affecting development.


Figure 1. TD 15 at 11:50am EDT 9/23/10, as seen by NASA's Terra satellite.

Forecast for TD 15
An upper-level high pressure system lies to the west of TD 15, near the coast of Nicaragua. The clockwise flow of air around this high will bring a moderate 10 - 20 knots of wind shear over TD 15 today and Friday. There is some dry continental air lying to the northwest of TD 15, and this shear may be able to drive dry air into the storm, slowing intensification and keeping TD 15 below hurricane strength through Saturday morning. By Saturday afternoon, TD 15 will move more underneath this upper-level high, causing the shear to decline. The SHIPS model forecasts that shear will fall to the low range, 5 - 10 knots, Saturday through Monday. This drop in shear should allow for intensification of TD 15 into a hurricane, if the center stays more than 50 miles offshore.

The future track and intensity of TD 15 depends critically upon the storm's interaction with land over the coming days. If TD 15 misses making landfall in Nicaragua and Honduras, and instead skirts the north coast of Honduras, the storm is likely to intensify into a hurricane by Sunday, as indicated in the official NHC forecast. However, if TD 15 spends significant time over or barely offshore of Honduras, the storm will likely stay below hurricane strength. TD 15 is being forced just north of due west by a strong ridge of high pressure. This ridge will keep the storm moving at 15 mph through Saturday. On Sunday, a trough of low pressure diving southwards over the Eastern U.S. will weaken the steering currents over the Western Caribbean and cause TD 15 to slow and turn more to the north. TD 15 will begin a period of slow and erratic movement on Sunday that may last many days, as the storm wanders in the Western Caribbean and over Belize, Honduras, and Mexico's Yucatan Peninsula. If the center of TD 15 spends significant time over water, the storm could easily develop into powerful and dangerous Hurricane Matthew. If the center remains mostly over land, TD 15 will still generate extremely heavy rains over Central America, but remain below hurricane strength. By late next week, the trough of low pressure over the Eastern U.S. may lift out, allowing a ridge of high pressure to build in and force TD 15 westwards across the Yucatan Peninsula and into the Gulf of Mexico's Bay of Campeche. Alternatively, the trough of low pressure over the Eastern U.S. may amplify, drawing TD 15 northwards across Western Cuba and into Florida. A complicating factor may be the development of a new tropical depression in the Central Caribbean 6 - 8 days from now, as predicted by both the GFS and NOGAPS models with their latest 12Z (8am EDT) runs. The uncertainties in the long-range fate of TD 15 are high, and depend strongly on slight variations in its track that determine how much time the storm spends over land. One thing that is virtually certain is that TD 15 will generate very heavy rains over Nicaragua, Honduras, Belize, and Mexico's Yucatan Peninsula Friday through Tuesday that will cause dangerous flooding rains and life-threatening mudslides.

Tropical Depression Lisa
Tropical Depression Lisa continues to churn the waters of the far Eastern Atlantic. By Saturday night, upper level winds out of the west are expected to increase, bringing high wind shear of 20 - 45 knots over Lisa. The high shear may be capable of destroying the storm by early next week. It appears unlikely that Lisa will affect any land areas.

Elsewhere in the tropics
The remnants of Hurricane Julia are still spinning over the far Eastern Atlantic, and are generating some sporadic heavy thunderstorm to the north of the center of circulation. Julia's remains are being given a 10% chance of re-developing by NHC.

Hurricane Karl's moisture causing flooding in Minnesota, Wisconsin
A plume of very moist air associated with what was Hurricane Karl last week has surged northwards over the Central U.S. over the past two days. This moisture is now being lifted over a warm front draped over Minnesota and Wisconsin, and has generated flooding rains in excess of six inches in southern Minnesota this afternoon. Flood warnings and flood watches are posted for a wide swath of the upper Midwest today, including most of southern Minnesota, northern Wisconsin, and Michigan's Upper Peninsula. These types of rain events are called Predecessor Rain Events (PREs), because they typically precede the actual arrival of the rain shield of a tropical storm.


Figure 2. Radar estimated rainfall over Minnesota.

Next post
I'll have an update on TD 15 Friday morning.

Jeff Masters

L 95 21st Sept. 2010 (TriniGirl26)
Neighbors help a driver to move his vehicle from the flood waters
L 95 21st Sept. 2010

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Quoting BDADUDE:
Thats not what the models are showing me dude!


you are looking at the statistical models.. not the dynamic
Member Since: April 17, 2010 Posts: 0 Comments: 1765
I am just saying but i think Matt is about to go RI on us. Look how orginized Matt has gotten.

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535. xcool


12Z Ensemble
Member Since: September 26, 2009 Posts: 2 Comments: 15743
Quoting bird72:


They got what? Earl? that's need to be a bad joke....rolleyes.jpg
actually they got Earl pretty good from about 3 days out
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Quoting hurricanehunter27:
Man if Matthew follows its NHC track its going to cause REALLY bad flooding in Mexico. I mean what are the rain fall estimates for this storm if it follows the track 30-40 inches? I think it is a good chance with Matt going Cat 1 over/near land. Also Fla better watch out beacuse were Matt is heading there are some really warm SST's.
How about Belize no trouble ? So many people fore get that Belize even exist
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Quoting key360:


not going to happen.


there is no evidence whatsoever to support Tropical Storm Matthew going to the western Gulf or Texas

How do you see that happening? The trough will create a weakness in the Eastern gulf
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Quoting Levi32:
Matthew's circulation continues to get better-defined. Steady strengthening should continue until it interacts with Nicaragua/Honduras in 24-36 hours.


Matthew could become a large system especially if it's able to survive any land interaction.
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All NOAA Tropical Imagery
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Quoting BDADUDE:
By the look of Matthews track there is no reason to frett in Florida dudes.


Who is fretting?
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Quoting NOLA2005:


Very nice, Pat! Wish I could help out, but I don't think I'll ever be able to afford any work by the "Mad Potter". Unless I stop paying the mortgage, quit feeding the pets...lol


He was quite the character,and its amazing that Piece we been lugging around for 4 generations was his,,and not to have been damaged thru our Post_K wanderings is extra amazing.

I bet he is smiling wherever he is tonight.
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Quoting washingtonian115:
When can we expect the "Wilma" refrences to occur?

They started June 1st
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520. skook
Quoting WildWillyFL:
It is sad what this blog has become and I was most likely on a lot of the people I am missing ignore list. So that says a lot.

It is almost impossible to find a gem of wisdom in a page full responses. There just isn't an intelligent response to the NHC track, their logic and reasoning, different scenarios, why they're right / wrong, etc... With the exception of a few posters, I would be better off getting my tropical update information from a magic eight ball.



I'm pretty sure..... if you read Dr. Masters blog, he has some insight on how he feels Matthew will develop and possible tracks. He is the profession here....
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Quoting TropicalAnalystwx13:
BDADUDE, you obviously have no clue how good the NHC has been t his year...Even in the long run.

They nailed... got Earl...

You'd be a fool to go up against the NHC.


They got what? Earl? that's need to be a bad joke....rolleyes.jpg
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Quoting Patrap:
Shameless Auction Plug for a Mudbaby from The Picasso of Pottery George Ohr being offered Tomorrow and Saturday.

Portion of the proceeds to go to Portlight. So Bid High and often on this one of a kind piece.Over 110 years old.

George Ohr Auctioned Lot,,Jardiniere


Very nice, Pat! Wish I could help out, but I don't think I'll ever be able to afford any work by the "Mad Potter". Unless I stop paying the mortgage, quit feeding the pets...lol
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Quoting CosmicEvents:
Good to know. Thanks. And good luck in the auction. That's a wonderful piece. Can't believe you thought it was a spitoon for years...lol
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.
.
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btw....if the auction company calls with "advice" to lower the reserve at the last minute before the auction....don't fall for that. Big-time auction houses are known for doing this. It's happened to me a few times.


Thanks ,,but the Auction House here,St Charles Gallery,,is renowned nationally and we have a Great contract,

The 24 Million Dollar Ohr/Okeefe Museum opens in Biloxi in November,so the timing is excellent.

Ohr O'keefe Museum
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Quoting WildWillyFL:
It is sad what this blog has become and I was most likely on a lot of the people I am missing ignore list. So that says a lot.

It is almost impossible to find a gem of wisdom in a page full responses. There just isn't an intelligent response to the NHC track, their logic and reasoning, different scenarios, why they're right / wrong, etc... With the exception of a few posters, I would be better off getting my tropical update information from a magic eight ball.
Here you go.
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Man if Matthew follows its NHC track its going to cause REALLY bad flooding in Mexico. I mean what are the rain fall estimates for this storm if it follows the track 30-40 inches? I think it is a good chance with Matt going Cat 1 over/near land. Also Fla better watch out beacuse were Matt is heading there are some really warm SST's.
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Matthew's circulation continues to get better-defined. Steady strengthening should continue until it interacts with Nicaragua/Honduras in 24-36 hours.
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Quoting TropicalAnalystwx13:


I knew Matt was in some warm water but geez!
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I would be better off getting my tropical update information from a magic eight ball.

Vortfix's eight ball?
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I find it very sad that there are more comments from people about what storms will be referenced by other than there are about the storm itself

We know this system will have an impact on someone; whether it be Nicaragua, Honduras, Belize, Cuba, Mexico or Florida; this will impact someone. How about this for a concept?. Lay off peoples comments, quit the sarcastic responses that have no benefit and actually track the damn storm.
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18z Early Cycle NHC model tracks
TS Matthew
Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)





Dynamic Models (More sophisticated models)





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Quoting washingtonian115:
When can we expect the "Wilma" refrences to occur?


Unfortunately, NOW since you mentioned it...
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Quoting Patrap:


That is a anomaly known to the site as "clock drift",which was repaired by a software fix.
Good to know. Thanks. And good luck in the auction. That's a wonderful piece. Can't believe you thought it was a spitoon for years...lol
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btw....if the auction company calls with "advice" to lower the reserve at the last minute before the auction....don't fall for that. Big-time auction houses are known for doing this. It's happened to me a few times.
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Quoting CybrTeddy:
Lots of the global models, all that I see, take Matthew into Central America and kill it, but develop another system and take it to Florida.


Despite all the wish casting, that's the most likely scenario..
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Calling DestinJeff...

Calling DestinJeff...

Calling DestinJeff...
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Quoting FLdewey:
THE REED CONE HAS BEEN REVEALED!


Yes look and be amazed at the red line! I'm out, ttyl
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Matthew becoming a player now I see...

Gotta watch this one. Hopefully I don't have to call for Hurlo... (PATRAP - Might want to get Hurlo prepped)
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One of our local mets in Orlando showed a model that has it coming right over central Florida. What concerns me is what strength it will be when it gets here because it is supposed to stall at 3 MPH as it reaches the Gulf.
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The Fujiwhara effect or Fujiwara interaction is a type of interaction between two nearby cyclonic vortices, causing them to appear to "orbit" each other.
GFS may be on to something.
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When can we expect the "Wilma" refrences to occur?
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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather

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