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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Quoting CJ5:
ExTD2 continues to maintain itself today and still could become a threat later on...


The models certainly hint at it. It needs to build upon DMAX.
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1033. Patrap
A faster forawrd speed for sure by those Numbers Ike..90L is gonna take some time,Like another 24 as Jeff says above,..all that Circ takes a Longer time to wrap up but rest assured shes doing it ,albeit slowly.
When we get that CoC established and some G-4 Sniffs come Mon,..Tuesday,a Lot Better Pic will come into Focus Im sure.

But the Blog may wind Up in Low Earth Orbit with JFV at the Apogee.
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1031. CJ5
ExTD2 continues to maintain itself today and still could become a threat later on...
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1030. rxse7en
Quoting Twinkster:



wow that is TD 2 you idiot not 90L. LOok before you post
Lighten up, Frances.
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1029. KEEPEROFTHEGATE (Mod)
258

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1028. fmbill
Quoting IKE:


Moving faster too...INITIAL CONDITIONS...
LATCUR = 14.7N LONCUR = 43.2W DIRCUR = 275DEG SPDCUR = 15KT


It's running away from the one behind it :-)
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Quoting fmbill:


I asked this earlier todya, but had to run out before any replies.

Why did WU take TD2 off the map?

We seem to track undeveloped waves all the time. Why wouldn't we would track remnant lows that have not dissapated, AND have model support of possible regeneration?


NHC isn't posting advisories on it. All of the WU "current" and "historical" data is straight from the NHC.
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I'm glad the models are aiming in the general direction of Florida. It means it won't be anywhere near here a week from now :P
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000
WHXX01 KWBC 141843
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1843 UTC FRI AUG 14 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL902009) 20090814 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090814 1800 090815 0600 090815 1800 090816 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 12.5N 28.8W 12.6N 32.1W 12.6N 36.1W 12.1N 39.9W
BAMD 12.5N 28.8W 12.8N 31.5W 13.1N 34.7W 13.3N 38.4W
BAMM 12.5N 28.8W 12.7N 31.8W 13.0N 35.4W 12.9N 39.3W
LBAR 12.5N 28.8W 12.7N 32.0W 13.1N 35.8W 13.6N 40.1W
SHIP 25KTS 30KTS 39KTS 51KTS
DSHP 25KTS 30KTS 39KTS 51KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090816 1800 090817 1800 090818 1800 090819 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 11.5N 43.5W 11.5N 48.0W 15.2N 52.7W 18.4N 61.5W
BAMD 13.5N 42.4W 13.7N 49.9W 13.8N 55.3W 15.8N 59.5W
BAMM 12.8N 43.2W 12.3N 49.6W 13.7N 53.5W 17.6N 58.7W
LBAR 14.2N 44.8W 14.4N 52.9W 14.9N 54.5W .0N .0W
SHIP 62KTS 80KTS 92KTS 95KTS
DSHP 62KTS 80KTS 92KTS 95KTS

...INITIAL CONDITIONS...
LATCUR = 12.5N LONCUR = 28.8W DIRCUR = 280DEG SPDCUR = 14KT
LATM12 = 11.8N LONM12 = 25.1W DIRM12 = 283DEG SPDM12 = 14KT
LATM24 = 11.6N LONM24 = 23.2W
WNDCUR = 25KT RMAXWD = 75NM WNDM12 = 25KT
CENPRS = 1007MB OUTPRS = 1011MB OUTRAD = 200NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

$$
NNNN


Member Since: August 23, 2008 Posts: 7 Comments: 5300
1024. rxse7en
Quoting IKE:


LOL...he's asked the same question a hundred times.

cued up for ya!
IKE, I think this one fit him better. http://www.youtube.com/watch?v=qh3J2j_fvCA

Love when we break out the Zep vids every season ; )
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Ex TD 2 is really starting to interest me now. It is the most immediate threat and has a FL surprise all over it. Wouldn't surprise me to hit as a Cat 1/2 with 90L on its heels...
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Quoting disneyfaninnawlins:


Boarding the windows is not worth it in the end! We did for Katrina and having the house dark and hot made the mold grow twice as fast! We also had a tree fall thru the house and knocked off the boards we put up on the windows in that room. After that experience we will never board up again.

Boarding up is good for stopping most projectiles, but the boards should be removed ASAP after the storm, to allow for ventilation.
Boarding up will not stop something like the point of a 4x4 plowing through at 100mph, but the chances of that particular situation happening is somewhat slim.

A better option is to get hurricane windows, as they have a clear plastic layer between two sheets of glass, and they *will* stop a 4x4. (they will also prevent break-ins).
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Is the DAM model running?
Member Since: March 19, 2009 Posts: 0 Comments: 1421
1018. fmbill
Quoting extreme236:
SHIPS 18Z makes 02L a 76 knot hurricane at 120 hours.


I asked this earlier todya, but had to run out before any replies.

Why did WU take TD2 off the map?

We seem to track undeveloped waves all the time. Why wouldn't we would track remnant lows that have not dissapated, AND have model support of possible regeneration?

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1016. Drakoen
BAM guidance takes it close to Florida
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TAFB and SAB at T1.5 still for 90L.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting disneyfaninnawlins:


Boarding the windows is not worth it in the end! We did for Katrina and having the house dark and hot made the mold grow twice as fast! We also had a tree fall thru the house and knocked off the boards we put up on the windows in that room. After that experience we will never board up again.


Hurricane shutters (especially the accordians) are the way to go. Takes 2 seconds to pull them across and they work better than plywood.
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1011. IKE
Quoting Cotillion:
000
WHXX01 KWBC 141836
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1836 UTC FRI AUG 14 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE TWO (AL022009) 20090814 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090814 1800 090815 0600 090815 1800 090816 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 14.7N 43.2W 15.2N 45.2W 16.1N 48.0W 17.4N 51.8W
BAMD 14.7N 43.2W 15.4N 45.5W 16.5N 48.2W 17.6N 51.3W
BAMM 14.7N 43.2W 15.1N 45.3W 15.9N 48.0W 16.6N 51.2W
LBAR 14.7N 43.2W 15.1N 45.7W 15.8N 48.8W 16.8N 52.2W
SHIP 25KTS 30KTS 37KTS 43KTS
DSHP 25KTS 30KTS 37KTS 43KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090816 1800 090817 1800 090818 1800 090819 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 19.3N 56.2W 23.3N 64.9W 27.0N 70.9W 29.4N 73.4W
BAMD 18.8N 54.7W 21.1N 61.9W 23.7N 68.0W 24.9N 71.5W
BAMM 17.5N 55.1W 19.5N 63.6W 21.9N 71.3W 24.0N 77.0W
LBAR 17.8N 55.9W 20.3N 63.4W .0N .0W .0N .0W
SHIP 51KTS 65KTS 71KTS 76KTS
DSHP 51KTS 65KTS 71KTS 76KTS

...INITIAL CONDITIONS...
LATCUR = 14.7N LONCUR = 43.2W DIRCUR = 275DEG SPDCUR = 15KT
LATM12 = 14.4N LONM12 = 40.1W DIRM12 = 277DEG SPDM12 = 12KT
LATM24 = 14.2N LONM24 = 37.9W
WNDCUR = 25KT RMAXWD = 40NM WNDM12 = 25KT
CENPRS = 1007MB OUTPRS = 1010MB OUTRAD = 150NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

$$
NNNN


Now up to hurricane strength.


Moving faster too...INITIAL CONDITIONS...
LATCUR = 14.7N LONCUR = 43.2W DIRCUR = 275DEG SPDCUR = 15KT
Member Since: June 9, 2005 Posts: 23 Comments: 37860
1010. 7544
Quoting StormChaser81:


The blog crashes my internet explorer every time I use it. I have to use firefox to use the blog now, just a update for all of you weather lovers. Some is happening with this blog.


thanks will do the same it does seem fine there
Member Since: May 6, 2007 Posts: 0 Comments: 6874
Quoting hurricane23:


Kills it for a while thens brings it back to life in the banamas and then into florida.


I'll keep a closer eye on this system, for conditions will certainly be favorable ahead of it. 90L is still a week away from even nearing the islands.
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Thanks for the T# update all... I fixed my post, since I don't have quite a few links here at the office.
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Quoting MandyFSU:


Thanks! I'll definitely look into them.


Boarding the windows is not worth it in the end! We did for Katrina and having the house dark and hot made the mold grow twice as fast! We also had a tree fall thru the house and knocked off the boards we put up on the windows in that room. After that experience we will never board up again.
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1006. Drakoen
Quoting hurricane23:


I was just thinking how it regenerates the little sucker.


Which is possible
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SHIPS 18Z makes 02L a 76 knot hurricane at 120 hours.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting RMM34667:


My sister was on St. Thomas for Hugo. Then she was on the first plane out after Marilyn in 1995. She said NEVER again. The hurricane is one thing but the aftermath is hell.


Yes, the hurricane is terrifying enough...but the aftermath can really feel like hell on earth for multiple reasons. I'm the same way...."never again"
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1003. Thaale
Quoting WeatherStudent:
Guys, remember, even if this latest run of the ECMWF Model continues to show a fish storm, it'll still be the odd man out. Since it's presently literally the only one model out of the entire package that's doing so with our future storm. Therefore, it will most likely be given very little to no consideration. Even the NHC knows this, besides the fact that it's an overall good model. It has a tremendous poleward bias.
Yeah, but it's been the best model all year (and wasn't it pretty good last year?), and BTW it's usually better with undeveloped systems anyway. Consensus science is bad science; you don't ignore the model with the best track record just because it's an "outlier." And you should take with a healthy dose of skepticism the GFS when it's projecting future movements of what's still nothing more than a low. Once there's an actual storm for them to project the future track of, the GFS and GFDL will have more reliability.
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Quoting Drakoen:


Must be an inside joke


I was just thinking how it regenerates the little sucker.

Not buying that right now.
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Quoting Drakoen:


Must be an inside joke


Must be...
Member Since: April 26, 2009 Posts: 3 Comments: 3667
1000. JLPR
and plywood bahh xD

My concrete house can get thru a Hurricane no problem =]
and I had no plywood during Georges and watched everything flying, including a neighbor's 2nd floor house roof =\
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GFS ensemble:

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Quoting Patrap:


Listen sport,If the Malware is embedded in a Ad Banner ,or a Page Load,its not gonna be a Human jumping up and Confessing to you Like your the Maker..get a grip..unplug from the web and do a Virus scan,.
I suggest AVG,or other good one


The blog crashes my internet explorer every time I use it. I have to use firefox to use the blog now, just a update for all of you weather lovers. Some is happening with this blog.
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Quoting extreme236:


90L is at T1.5 and 02L is at 1.0


90L could likely by a TD by tomorrow?
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Quoting CaneWarning:


What's so funny. I looked...


Must be an inside joke
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Quoting hurricane23:
Lol look at this!



It went from Category 5 to a Tropical Storm. That shows you how little we know from this point on intensity.
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Quoting futuremet:
Adrian

What does the ECMWF make up of EX02L?


Kills it for a while thens brings it back to life in the banamas and then into florida.
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Quoting hurricane23:
Lol look at this!



This has a greater chance of happening than 90L hitting FL.
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Quoting jeffs713:

GFS - everyone is freaking about what is now 90L hitting SE FL.
GFDL - cat 3 in 5-7 days north of the islands
HWRF - Apocolyptocane north of Hispaniola in 7-ish days.

T#s:
Not sure about former TD2.
90L is still at 1.0/1.0.

The blog:
A third the blog is freaking out about the GFS model.
JFV/WS is already worried.
A third of the blog is laughing at the first third.
The final third of the blog is actually talking about pertinent tropical stuff.


90L is at T1.5 and 02L is at 1.0
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting hurricane23:
Lol look at this!



The SHIPS are even stronger
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Hurricane Preparation Entry
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Quoting hurricane23:
Lol look at this!



What's so funny. I looked...
Member Since: April 26, 2009 Posts: 3 Comments: 3667
SHIPS forecast for shear to be very favorable for TD2. I'm starting to think it could be a real player...
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Td2 isn't looking too bad right now structure wise
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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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