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Tropical Depression Five forms

By: Dr. Jeff Masters, 7:55 PM GMT on August 24, 2006

The Hurricane Hunters found a closed circulation and surface winds of 35 mph in the tropical wave moving through the Lesser Antilles, so this system is now Tropical Depression Five. Here's the 3:30pm EDT statement from NHC:

Reports from an Air Force reconnaissance plane indicate that the tropical wave moving westward through the Windward Islands has developed a closed wind circulation...and advisories on either a tropical depression or tropical storm will be initiated at 5 PM AST. Maximum winds at this time appear to be just below tropical storm strength...but it is possible that stronger winds may be observed prior to advisory time.

The new center that developed 100 miles north of the South American coast this morning is beginning to consolidate, with a new line of intense thunderstorms developing to the south of the center. This new spiral band joins the older spiral band to the east, which has brought wind gusts as high as 51 mph to the Islands today. It is clear that this will be Tropical Storm Ernesto in short order.

Current conditions in the islands
Barbados reported sustained winds of 32 mph at 5am this morning, and wind gusts as high as 51 mph. Togabo had wind gusts to 36 mph, and sustained winds of 33 mph with wind gusts to 43 mph were observed on St. Lucia. A QuikSCAT satellite pass from 6:30am EDT shows a large area of 35 mph winds to the north of the center. Radar from Martinique shows the heavy bands of rain spreading over the islands. Winds on Martinique have gusted to 35 mph so far today.

Wind shear
Upper level winds out of the west are creating about 5-10 knots of wind shear over the center, which is not significantly inhibiting development. The shear is forecast to remain low through the next five days. There is a zone of very high shear to the system's north, but it is forecast to retreat to the west ahead of the developing storm. The evolution of the shear pattern over the past 24 hours has matched what the GFS has said would happen, so this gives me confidence that the shear forecast is correct, at least for the next day. This system does have the potential to become a hurricane by early next week.

The computer models
The latest 8am EDT (12Z) computer model runs were all initialized with the old center position, and thus are unreliable. We'll have to wait until the 18Z (2pm EDT) model runs are available late tonight before we can put much stock in any of the computer model solutions. With this in mind, here is my what the latest 12Z computer models say:

The Canadian model continues to be very consistent, and develops Ernesto into a hurricane south of Jamaica, that then tracks into the Gulf of Mexico. The NOGAPS model is also consistent, assuming a more southerly track will occur with little development due to close proximity to the South American coast. This forecast is already incorrect, and can be discounted. The GFS takes a weak tropical storm across the Dominican Republic on Saturday, then into the Bahamas. The GFDL takes a strong tropical storm into Haiti on Sunday, then on a long path over eastern Cuba. On Tuesday, the GFDL has the system emerging from the coast of Cuba as a weak tropical storm and passing through the Florida Keys. The run-to-run consistency of the GFDL has been poor, and both the GFDL and GFS have not done a good job forecasting the initial track of the storm so far.


Figure 1. Current satellite image of TD 5.


Figure 2. Preliminary model tracks for TD 5.

Debby
Tropical Storm Debby remains a minimal tropical storm today, but is expected to slowly intensify in response to some warmer waters along her path the next two days. By the time Debby turns north this weekend, she could attain hurricane status. Early next week, Debby is expected to get caught up in the jet stream and die in the North Atlantic.

My next update will probably be Friday morning.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

hey guys - looking at the wind shear map on stormjunkie's site, I see very low shear - what am I missing?
You're not looking at SJ's site again!
Usually he would have responded by now.
Am I bugging out because of lack of coffee or does it look like there is/was 2 eyes trying to form on the visible loop?
2505. HCW
I don't like to Compare storms but I can't help to think of IVAN when I see the forecasted track and the models. I think that NHC still has lots of room for improvment when it comes to forecasting intensity

Hardcoreweather.com
Link
miracleaa1990...Send him an email. He'll get back with you.
That's what I said yesterday HCW.
Does the Quikscat experience limitations at night? Perhaps thats why it wasn't upgraded at 5am. Or could they be waiting for the HH to fly through again.

I don't know very much about tropical cyclones but this does look like a TS to me.
SJ- about the Carolina system:

I've notice some rotation around a dry center on the Charleston radar. The system lost a lot of convection last night when it moved offshore, which is consistent with a mesoscale complex, but it's rebuilding some convection this morning. Combine that with the GFS/GFDL models and we still need to keep an eye. Aything that would develop would have to sit there for awhile, though.
2512. fla1963
StormW

You are correct, that's whats happening
2514. mm17
New poster here....Lower Florida Keys, 17 miles up the road from Key West on Sugarloaf. I see a few Key Wester's posting here and I say hello to y'all. Been here in the Keys 30 years ans seen any number of TS and Hurricanes. Georges in 1998 was by far the worst, with last years Wilma a second. The storm surge from Wilma was something long time Key Westers who have lived here 50-60 years or more had never seen. Had a bit better than 8 foot surge here on Sugarloaf Key.......funny thing was it came at the tail end of the storm, when winds were down to 30 knots or so...and man did it come up fast.
Keeping a close eye on this Ernesto...Cheers to all.
1990, there are several different shear forecasts, and they do not always alighn with each other the way you would think they should.

Rand...Thanks...Sorry for delay....Quick Links
ihave27windows...The Scat depends on the orbit. Not the invest.


be interesting to see what recon finds later! :)

Settle down Rand :)....I was responding to your request!
On a side note don't you just feel a little bad that Pluto has been booted from the family....
hey i think this storm will do the track that the nhc siad it will do i noted that in the last few loops
2524. IKE
Appears to be moving almost due west. Maybe it'll stay on that course and head into the Yucatan...not wishing harm on them.....
Is shear affecting this storm right now? Last few frames convection has decreased

image
2526. emagirl
anyone have a guess on the chance TD5 will make it past this shear
2527. ricderr
yeah SJ Mickey must be crushed
and who said comedy was dead.....nice job jp......back to bed with you.....LOL
The Yucatan is actually quite populated. I was there just before Gilbert hit, and if you can't speak or understand spanish, you're SOL because no one is going to tell you a hurricane is coming.
I thought you said (twice) you were off to sleep JP - obviously an addict:-)


looks like recon should be able to find TS force winds with np.....
I had posted something humourous before about Jamaica and Hurricanes, People are saying that global warming is making the storms become intense but most of biggest storms pass through the caribbean and near Jamaica, for example, Wilma, Dennis, Emily, Ivan, Gilbert. When we see these storms coming we greet them with Marijuana and that makes them High and confuse and enabling them to shift from Jamaica. However in making them High and confused it also causes them to intensify and Pres Bush may need to look into this and place some Ganja along the entire golf coast so that the storms will turn away and not be mad like Katrina.

LOL, Undertaker. I see why Katrina and Rita got so mad - no ganga in the Bahamas . . . .
katrina2005 by the looks at it i have some loop of the storm up of my own and what it seen like no it is doing vary well right now
Wake up Dr. Masters. We want to hear your take.
thelmores - Yes, Hurricane Hunters might find tropical storm force winds but some of those high wind areas you have pointed out might be rain contaminated.
I want to hear ST's take.
Can someone give me a link to see the buoys out there??
nevermind I found it...
2542. ricderr
stormW..and may i ad...."da da da boom"..humor before 10 am..morning fischer
2547. ricderr
27...where in the yucatan....when the kids were younger...we liked to go to merida....hike the ruins...then head up and over to cozumel and dive....not a big fan of cozumel but i could retire to merida
SW....looks like someone may have given the Canadian some of that ganja....
Thx though Raylog and StormJunkie...BTW Storm your site is very nice...And just so my two cents are in on this storm... From what I'm seeing I would have to agree with some earlier bloggers that the center is not as far west as the NHC has it. The shear obviously is eating away at some of the western most convection however I think the center is somewhat embedded inside the thunderstorms.
windows.... I was in Mexico last year for Emily. The locals refused to admit that a hurricane was coming until the last minute. Most of the people in my resort were from Michigan and such. Me being from Florida knew better. Spent 2 days in a Mexican hurricane shelter. Pure hell. Would have rather stayed in my destroyed resort.
9:15amEDT- Tropical Depression 05 continues to fire convection in the SE Caribbean Sea.

MiamiFisher, Tuesday is our anniversary. I really do not want to think it. That was a terrible day!
It must be the Pluto problem...Hell I remember when they found that planet!
MiamiFisher, there are many functions going on on Tuesday. There will be rememberence services all over the place.
September is worse, MiamiFisher.

(Well, for old people, anyway)
2560. ricderr
Hell I remember when they found that planet!
hmmmm...let's see..that was before electricity.....running water....one room schools....damn rand..you're old!!!!!...lol
The area off the Carolina coast continues to build convection....
what are the chances that the high mountains of Hispaniola can take out Ernesto???

would hate to see the poor people their if that did happens, half the island has little or no vegitation, and floods easily with massive mud slides......

be nice if we could add this storm to the fraveyard..... i just dont see that.... yet!
2563. HCW
This storm needs to slow down if it wants to bomb out . When it does slow down it may be in a 20 to 30kt shear zone

Hardcoreweather.com

Link
SJ- Did you see my earlier post about the Carolina system? I'm picking up some rotation on radar.
2565. guygee
New Blog.
2566. BrnGrl
total weather newbie here...

so, let's just say -hypothetically- that Ernie makes it into the Gulf...does anyone see anything to steer it away from Freeport/Galveston? The only thing that saved us from Rita last year was an area of high pressure sitting over Houston. Could we be that lucky again?

WEST CENTRAL AND SOUTHWEST FLORIDA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAMPA BAY RUSKIN FL

CHANGES BEGIN FOR TUESDAY THROUGH THURSDAY BECAUSE OF
TROPICAL DEPRESSION 5...NOW OVER THE WINDWARD ISLANDS. PREFER THE
NEW GFS SOLUTION BASED ON THE 00Z 25 AUG RUN. TD 5 IS LIKELY TO
EMERGE FROM THE CARIBBEAN SEA THROUGH THE YUCATAN CHANNEL ON
TUESDAY ...WHILE A 591 DM 500 MB HIGH IS POSITIONED OVER THE
NORTHEAST GULF WITH A CENTER NEAR TAMPA.
THE FORECAST FOR TUESDAY THROUGH THURSDAY WILL BE HIGHLY DEPENDENT
ON THE TRACK OF TD 5. GFS GUIDANCE INDICATES AN INCREASE IN DEEP
TROPICAL MOISTURE ON SOUTHERLY FLOW BEGINNING LATE TUESDAY THROUGH
THURSDAY AS MOISTURE FROM TD 5...LOCATED SOMEWHERE IN THE EASTERN
GULF...IS ADVECTED INTO OUR REGION. WILL OPT TO TREND POPS UPWARD
INTO THE LIKELY CATEGORY ONCE AGAIN BEGINNING WEDNESDAY AFTERNOON
AND AGAIN ON THURSDAY AFTERNOON. THIS MAY ALL CHANGE IF THE ACTUAL
TRACK OF THE TROPICAL CYCLONE KEEPS IT FARTHER AWAY FROM OUR
REGION.
A new blog is up
"The area off the Carolina coast continues to build convection...."

Hey SJ.... if i started drawing circles and squiglt lines and circles off the sc coast, it would take a while!!! LOL



Somebody needs to answer the Gulf question above before I do please.
I saw it Sav...It only looks like it will have about 48 hours to sit there before it starts moving back towards the coast...
People here keep hoping the TD5 goes west - less damage that way. However, there is just no easy way out with this storm, unless it fizzles altogether. The whole western and northern Caribbean Sea is ringed by higly populated areas.

Best we can hope for is that people in the affected area are prepared. It's good to see people from all the isles checking in, too. I hope people on the Hondurus / Belize coast are also monitoring. Right now the forecast track seems fairly certain, but when storms get to that area of the western Caribbean where Wilma intensified last year, lots of things change very quickly. The NHC doesn't seem too confident about their intensity forecast, and we all know that larger, more intense storms can behave very differently from Twaves and TDs. So everybody in the area should be at least monitoring forecasts.

Here in the Bahamas I haven't run out to buy extra water or pulled out my shutters or anything. But like other weather-savvy Bahamians, I'm keeping a weather eye on the SE Caribbean. (and that's not just because I like following the storms).
2576. emagirl
just watched TWC they are saying that they think the wind shear will either be gone by the time TD5 makes it or that it wont affect it they are talking like this storm will make it and strengthen....i have a bad feeling
2578. BrnGrl
did I say something wrong? :)
so twc said the shear wont affect the td
Watching the visual loop, it seems like the COC is right on the western part of Ernesto. At least there is a hint to that.
2581. fla1963
I think this passed TD status along time ago!
2587. BigToe
Afternoon All,
Gee, 1st Pluto's gone and now Ernie'e COC is uncovered. You miss alot when you go to work.
Rand... go for it...answer the GULF question