Disturbance 90L close to tropical depression strength; TD 2 may rise again

By: Dr. Jeff Masters , 2:02 PM GMT on August 14, 2009

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A strong tropical wave (90L), with a large circulation and a moderate amount of heavy thunderstorm activity, is a few hundred miles southwest of the Cape Verdes Islands, off the coast of Africa. This morning's QuikSCAT pass shows that 90L has a large circulation, but this circulation is not yet well-formed, as it is elongated along an east-west axis. Satellite imagery from the European METEOSAT satellite show that the heavy thunderstorms associated with 90L are gradually becoming better organized, with some spiral banding evident on the south side of the storm. Satellite intensity estimates from NOAA already put 90L at tropical depression strength with 30 mph winds, but the storm does not yet have a well enough formed circulation to be classified as a depression. Water vapor imagery shows that since 90L is forming several hundred miles south of the dry air of the Saharan Air Layer (SAL), the storm should not be affected by dry air and dust as much as Tropical Depression Two was. However, there is some dry air from the SAL being sucked into the circulation of 90L, and this is retarding its development.

Wind shear is moderate, about 10 - 15 knots, but is forecast to fall to the low range, 5 - 10 knots, later today. Shear is then forecast to remain low for the next five days. Sea Surface Temperatures are about 28°C, and will remain in the 27 - 28°C range the next five days. The combination of low wind shear and sufficiently warm SSTs should allow 90L to develop into a tropical depression by Saturday, and potentially reach hurricane strength by Wednesday. Most of our reliable models strengthen 90L into a hurricane by Wednesday, when the storm is expected to be near the northern Lesser Antilles Islands. One important outlier is the ECMWF model, which has 90L passing to the north of the islands, and eventually recurving out to sea east of Bermuda. The ECMWF was by far the most reliable model for forecasting hurricane tracks last year. However, all of our models are pretty unreliable going out 5 days in advance for systems that have yet to reach tropical depression strength. Once 90L becomes a tropical depression and develops a well-formed circulation, the models will have a better handle on forecasting where it will go.


Figure 1. The remnants of Tropical Depression Two (left side of image) and tropical wave 90L (right side of image).

Tropical Depression Two may come back
Tropical Depression Two died yesterday, but may rise again. Satellite loops of the remnants of the storm show that heavy thunderstorms are again attempting a comeback near the axis of what is now a tropical wave. However, dry air continues to interfere with the development of the thunderstorm activity, and moderately high wind shear of 15 - 20 knots is also inhibiting the process. Wind shear over the remnants of TD 2 is expected to remain in the moderate range, 10 - 20 knots, over the next four days. Sea Surface Temperatures (SSTs) are 27°C, but will warm to 28°C two days from now. There is plenty of dry, stable air from the Saharan Air Layer (SAL) to the north and west that will continue to cause the storm problems. The relatively cool SSTs and dry air mean that any re-development of the storm will be slow to occur. NHC has given the system a medium (30 - 50% chance) of becoming a tropical depression again by Sunday morning. Only one reliable model, the NOGAPS, is predicting regeneration of TD 2. The NOAA Hurricane Hunters are flying research missions into the remnants of TD 2 today and Saturday.

I'll have an update Saturday morning, or earlier, if significant developments occur.

Jeff Masters

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former td2 looks more impressive this afternoon imo
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Why do you people keep feeding WS? He's a troll. Ignore him like everyone else.
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832. slavp
Quoting LouisianaWoman:
I chatted with you a bit last night, LB. I'm from Delcambre, the town that is technically smaller than your hometown of Crowley. ;)
Well Howdy neighbor!!! Erath here!!! LOL
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831. IKE
TD2 looks headed for the northern islands, right now, on it's present path.
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NEW TROPICAL STORM FORECAST TO DEVELOP AFTER 12 HOURS
FORECAST POSITION AT T+ 12 : 11.3N 28.9W

VERIFYING TIME POSITION STRENGTH TENDENCY
-------------- -------- -------- --------
00UTC 15.08.2009 11.3N 28.9W WEAK
12UTC 15.08.2009 11.8N 33.1W WEAK LITTLE CHANGE
00UTC 16.08.2009 11.3N 36.6W WEAK LITTLE CHANGE
12UTC 16.08.2009 11.7N 39.7W WEAK INTENSIFYING SLIGHTLY
00UTC 17.08.2009 12.8N 43.5W MODERATE INTENSIFYING SLIGHTLY
12UTC 17.08.2009 13.4N 47.0W MODERATE INTENSIFYING SLIGHTLY
00UTC 18.08.2009 14.2N 50.4W MODERATE LITTLE CHANGE
12UTC 18.08.2009 14.8N 54.2W MODERATE LITTLE CHANGE
00UTC 19.08.2009 15.8N 57.7W STRONG INTENSIFYING SLIGHTLY
12UTC 19.08.2009 16.0N 61.0W STRONG LITTLE CHANGE
00UTC 20.08.2009 16.6N 64.4W STRONG INTENSIFYING SLIGHTLY
12UTC 20.08.2009 17.4N 67.9W STRONG LITTLE CHANGE
Member Since: October 28, 2006 Posts: 57 Comments: 30825
Quoting CaicosRetiredSailor:



NHC Crayon art for this page.

I can't help but to laugh at the idea of "crayon art"
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Quoting IKE:


90L is THREE-THOUSAND MILES away from south Florida.

No one on here can answer your question.



Come on IKE, I figure that it's about 2800 miles away. Surely we can predict where it's gonna hit now. LOL
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I chatted with you a bit last night, LB. I'm from Delcambre, the town that is technically smaller than your hometown of Crowley. ;)

Oh yeah lol well i live in a much bigger city now...I'm stationed in Monroe :)
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Alright guys, I've posted my analysis of the situation, check it out and tell me what you think of it! :)
90L Gradually becoming better organized and will TD2 rise from the dead?
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Quoting hurricanehanna:

Most home centers/hardware stores have them - cheap to. Easy to pop the wood in and out of the area framing the window.


Go to www.plylox.com and click on Stores and you can punch in your zip code to search for a store that carries them
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Former TD2 is losing its coldest cloud tops. It's beginning to look like an island surrounded by dry air.
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Quoting breald:


I think you may want to look into moving to Nebraska. It may keep you from having a heart attack.

Then he can have a better chance of seeing a cyclone annually... just slightly smaller, but more locally powerful.
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How much longer until the 12z Euro?
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819. IKE
Quoting WeatherStudent:



WOW, so your not concerned about 90L potentially affecting us down the road then, whatsoever? Thansk for that input. Hurr, I guess I'll be following your trend then, for the time being that is, :)


90L is THREE-THOUSAND MILES away from south Florida.

No one on here can answer your question.

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Link
Heavy rain in Florida due Area 4.
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I chatted with you a bit last night, LB. I'm from Delcambre, the town that is technically smaller than your hometown of Crowley. ;)
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LouisanaWoman:

And the added bonus is- if there's a run on plywood you're set... and so is the floor of your shed after the storm passes :)
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Quoting 7544:
attention POSTER 742 EVRYTIME YOU POST THOSE 3 AMINATION S THE BLOG FREZZES CAN YOU PLEASE LINK THEM its happen both time u post them on sep pages


No problems here, and I *like* those loops that P451 puts up. You might check that your Quicktime, Flash etc are up to date.
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Quoting Category5hitsNewYork:
I think 90L gets stuck by the ridge and hit SFL and then it curves when it gets into the GULF and it then hits TAMPA!


Thought I ignored you once. Guess I was wrong, but I'm about to fix that.
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NHC Crayon art for this page.
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Quoting hurricanehanna:

Most home centers/hardware stores have them - cheap to. Easy to pop the wood in and out of the area framing the window.


Thanks! I'll definitely look into them.
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809. IKE
Easterly shear is making 90L to where you can see the circulation on the east side of the convection.

No TD this afternoon.
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Quoting Skyepony:
So far today looks like AF303 chucked a sonde 195 miles (315 km) to the SSE (151) from New Orleans, LA, USA. It didn't get any wind data.. May have been a dud?


303 is out there eh Skye?..Keesler must be gearing up for the Wave a coming.

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hey Louisianawoman i'm Louisianaboy lol
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Quoting weathersp:


Seeing as it takes 5 hrs to get out there the 00z's may already be initiilised.. mabye the GFDL and HWRF wich run start their run at 1:15z. Global models will not get the data till 6z but that leaves all upper air soundings out... so 12z tomorrow we will havea good picture.


00Z is not initialized yet... 18Z is going to soon.

It might make it on time... but then again.
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Quoting MandyFSU:
hanna- never heard of plylox... will have to look it up and keep it in mind should, um, conditions warrant lol

Most home centers/hardware stores have them - cheap to. Easy to pop the wood in and out of the area framing the window.
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Yea, our plywood for the windows is currently the flooring for our shed. lol Now if a storm kicks up, we'll obviously have them on the windows again, but hey, it's multifunctional!
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Quoting LouisianaWoman:
Mandy---Now that's MY kind of shutters. Who needs something fancy when a sheet of 3 quarter inch do the job just as well, if not better!
Myself along with some other firefightersboard up houses for elderly folks in our area. After we get done with them, I'm lucky to have time to close my doors and turn off elec.
Quoting 7544:
attention POSTER 742 EVRYTIME YOU POST THOSE 3 AMINATION S THE BLOG FREZZES CAN YOU PLEASE LINK THEM its happen both time u post them on sep pages


I'm not having any problems
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Quoting CaicosRetiredSailor:
What models will be the first to incorporate the data from the reconnaissance flights below?


WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1000 AM EDT FRI 14 AUGUST 2009
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 15/1100Z TO 16/1100Z AUGUST 2009
TCPOD NUMBER.....09-078

I. ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY: PSBL LOW LEVEL INVEST
FOR 16/1800Z NEAR 17.0N AND 55.0W ON THE REMNANTS
OF TD-02.
3. NOTE: 1- THE G-IV WILL FLY A RESEARCH MISSION AROUND
THE REMNANTS OF TD-02 TODAY DEPARTING TBPB 14/2000Z
.
2- BOTH NOAA43 AND G-IV WILL FLY RESEARCH MISSIONS
IN AND AROUND THE REMNANTS OT TD-02 DEPARTING TBPB
15/2000Z.


-------------------

CRS


Seeing as it takes 5 hrs to get out there the 00z's may already be initiilised.. mabye the GFDL and HWRF wich run start their run at 1:15z. Global models will not get the data till 6z but that leaves all upper air soundings out... so 12z tomorrow we will havea good picture.
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798. Skyepony (Mod)
So far today looks like AF303 chucked a sonde 195 miles (315 km) to the SSE (151°) from New Orleans, LA, USA. It didn't get any wind data.. May have been a dud?
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Louisana Woman- we don't put on airs where I come from. Besides, if for some reason you need the plywood in the offseason it's ready for you. Can't say the same for the shutters! LOL
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795. 7544
attention POSTER 742 EVRYTIME YOU POST THOSE 3 AMINATION S THE BLOG FREZZES CAN YOU PLEASE LINK THEM its happen both time u post them on sep pages
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Regarding
Graphical Tropical Weather Outlook (Post #766) Cirle #4

and TWO "SHOWERS AND THUNDERSTORMS OVER THE NORTHEASTERN GULF OF MEXICO ARE ASSOCIATED WITH A WEAK TROUGH OF LOW PRESSURE.

Will this have any effect on lowering SST's in the NE GOM, or would there have to be development of a system to have an effect?

It would be an answer to a prayer.
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hanna- never heard of plylox... will have to look it up and keep it in mind should, um, conditions warrant lol
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Mandy---Now that's MY kind of shutters. Who needs something fancy when a sheet of 3 quarter inch do the job just as well, if not better!
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Quoting MandyFSU:
hanna- you're more sophisticated than my parents. We just grab a sheet and drill it up. Rinse & repeat. Mom made Dad leave her a little "peep hole" at the tops of the windows so she could at least see out. Bless her heart.

My husband recycles - EVERYTHING - so we reuse the plywood. Thank goodness for Plylox clips. Never thought of the peephole -good idea!
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The last few frames here, if you watch TD2 closely, it goes from being a fairly round circulation to seemingly cracking horizontally down the middle and elongating.

Shearing in the low/mid level flow responsible?

I still can't figure out other than resolution why other models (besides NOGAPS and the HWRF) don't show regeneration.

Maybe they're on to something and this shearing of the moisture is yet a new sign of trouble for the low...

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Quoting hurricanehanna:
Someone hide the crayons....NHC is at it again!

lol..
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Quoting Skyepony:


Totally agree~ weak systems, kinda close together. TD2 is tapping into 90L's convection a little here & there. Ways to go with these two.

East coast seabreeze is firing up here in Melbourne.


TD2 appears much tighter than 90L. 90L has a lot of work to do; it not only has to tighten up, but it has to get some deep convection over it's center.
Member Since: October 28, 2006 Posts: 57 Comments: 30825
90L no doupt appears to be currently impacted by shear easterly shear that is and if this continues it may very well track into the caribbean as the GFDL suggest.
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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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