Forecast for 92L: dissipation by Friday

By: Dr. Jeff Masters , 2:17 PM GMT on June 16, 2010

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A low pressure system about 700 miles east of the Lesser Antilles Islands, Invest 92L, was near tropical depression status early this morning, but is currently weakening. Infrared satellite loops show the disturbance's heavy thunderstorm activity has decreased markedly in the past few hours, with the cloud top temperatures warming noticeably, indicating that 92L's thunderstorms are no longer pushing as high into the atmosphere. Water vapor satellite loops show that the storm is surrounded on all sides by dry air, though there is a region of moister air in front of it that 92L will encounter on Thursday. Wind shear as diagnosed by the University of Wisconsin is near 20 knots, though the SHIPS model is diagnosing the shear at a higher 25 - 30 knots. This high shear is pushing 92L's heavy thunderstorm activity to the east side of the center of circulation, and the center will probably become exposed to view late this morning. Had 92L been able to maintain the heavy thunderstorm activity it had early this morning for 12 or so hours, it could have been classified as a tropical depression. However, classification as a TD requires persistent heavy thunderstorm activity, typically interpreted to mean 12 hours of consistent heavy thunderstorm activity, and 92L did not meet that criterion.


Figure 1. Morning satellite image of Invest 92L. Image credit: NOAA.

The forecast for 92L: dissipation
Wind shear is the main story in the forecast for 92L, as a band of very high wind shear of 20 - 50 knots lies to the northwest of the storm. The current expected track of 92L carries it into this band of high wind shear, and the SHIPS model (based on the GFS model) is predicting that the shear will remain in the 25 - 30 knot range through Friday. Other models predict higher shear levels. It is likely that the high shear, combined with the dry air surrounding the storm, will destroy 92L by Friday. The National Hurricane Center is giving 92L a low (10% chance) of developing into a tropical depression by Friday morning, and this is a reasonable forecast. It is likely that 92L will bring heavy rain showers and wind gusts up to 35 mph on Friday to the Lesser Antilles Islands. I don't expect 92L to be organized enough to cause flooding problems to any of the islands in its path. None of our reliable global computer models develop 92L into a tropical depression. The rest of the tropical Atlantic is quiet, and none of the reliable computer models is calling for tropical cyclone development in the Atlantic over the next seven days.

Is the formation of 92L a harbinger of an active hurricane season?
According to the Hurricane FAQ, Goldenberg (2000) found that during the period 1944 - 1999, formation of a named storm in the tropical Atlantic south of 22°N and east of 77°W during June and July was a harbinger of at least an average season, and in many cases an above average season. The formation of a storm in this region during June or July is one factor the NOAA and Colorado State University seasonal hurricane forecast teams have used in the past as a predictor for an active season in their early August forecasts. Now, 92L didn't make it to named storm status, though it was pretty close to being a tropical depression. However, the near-formation of 92L into a tropical depression, is, in my mind, a clear harbinger that we can expect a severe hurricane season this year. It's very rare to have a development like 92L in that portion of the tropical Atlantic this early in the season. The lower than average wind shear and higher than average SSTs that helped 92L get organized are more likely than not to carry over into the main portion of hurricane season, giving us a much more active hurricane season than normal.


Figure 2. Synthetic Aperture Radar (SAR) image of the oil spill taken at 7:51 am EDT Tuesday June 15, 2010, by the Canadian Radarsat-1 satellite, operated by MDA GeospatialServices of Richmond, Canada. A large amount of oil was present on the Florida Panhandle coast near Pensacola, and was headed east towards Panama City. Image credit: Center for Southeastern Tropical Advanced Remote Sensing, University of Miami Rosenstiel School of Marine and Atmospheric Science. SAR images have a resolution of 8 - 50 meters, and can be taken through clouds and precipitation.

Oil spill wind and ocean current forecast
Light and variable winds less than 10 knots will blow in the northern Gulf of Mexico for the next five days, according to the latest marine forecast from NOAA. The winds will tend to have a westerly component for the most part, which will maintain a slow (1/4 mph) eastward-moving surface ocean current that will transport oil eastwards along the Florida Panhandle coast, according to the latest ocean current forecast from NOAA's HYCOM model. These winds and currents may be capable of transporting oil east past Panama City, Florida to Cape San Blas by Monday. Oil will continue to threaten the coasts of Louisiana, Alabama, and Mississippi for the remainder of the week as well, according to the latest trajectory forecasts from NOAA and the State of Louisiana. The long range 8 - 16 day forecast from the GFS model indicates a typical summertime light wind regime, with winds mostly blowing out of the south or southeast. This wind regime will likely keep oil close to the coastal areas that have already seen oil impacts over the past two weeks.

NOAA has lauched a great new interactive mapping tool that allows one to overlay wind forecasts, ocean current forecasts, oil location, etc.

Oil spill resources
My post, What a hurricane would do the Deepwater Horizon oil spill
My post on the Southwest Florida "Forbidden Zone" where surface oil will rarely go
My post on what oil might do to a hurricane
NOAA has lauched a great new interactive mapping tool that allows one to overlay forecasts and oil location observations
Gulf Oil Blog from the UGA Department of Marine Sciences
Oil Spill Academic Task Force
University of South Florida Ocean Circulation Group oil spill forecasts
ROFFS Deepwater Horizon page
Synthetic Aperture Radar (SAR) imagery from the University of Miami

I'll have an update on Thursday.

Jeff Masters

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Quoting kmanislander:


The map shows the tendency has been falling for the last 24 hours but when it falls to 30 or 40 Knots from values above that it is really academic IMO. Nothing is going to get going in 40 knots.



YEP YEP......we both know that its very hard for anything happen above 20kts.....but ya the sheer is dropping! Will be interesting to see what is left if anything of 92L 850mb Vorticity...when it emerges from the strong Sheer.
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Quoting kmanislander:


Shear is higher during El Nino years. Right now we are neutral and on the way to La Nina


Yep, agree ;) Just was giving an example of climate time scale vs. synoptic time scale causes of shear.
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1114. Greyelf
Quoting clwstmchasr:
"Chicks dig me, because I rarely wear underwear and when I do it's usually something unusual".


"Got something in a low-rise bikini, mesh, if possible?"
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very interesting 6N 41W ....
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Quoting xcool:
poor 92L AND BLOG.


Last time the tropics in the Atlantic got quiet, we played guess the 'cane, posting an image of an old storm, and seeing who could guess it.
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Quoting NCHurricane2009:


With wind shear, you have to look at it day by day (synoptic time scale) and also you have to look at its trend the whole season when the seeason is over (climate time scale)

On a synoptic time scale, shear in the tropics is caused when an upper trough in the mid-latitude westerlies produced upper westerlies that oppose the tropical easterly trade winds. Sometimes, they get cut-off from the mid-latitude westerlies (stall) and constantly produce shear (like the TUTT in the Caribbean we've been talking about) when a deep-layered ridge amplifes to the northwest of it. During hurriacne season, upper troughs take further south tracks in June and November because the westerly polar jet is furthest south. The westerly polar jet is even further south during winter, and is furthest north during summer. The same can be said for the ITCZ.

On a climate time scale, El Nino increases shear and La Nina decreases shear. If you take time the average shear over the entire season during El Nino, you'll find its higher in the Atlantic.


Shear is higher during El Nino years. Right now we are neutral and on the way to La Nina
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1108. xcool
poor 92L AND BLOG.
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it looks like shear is relaxing I would not be surprised if we see a big drop (10-20kt maybe even 25kts) in shear in the next 3 days and 92L heads into the NE caribbean and I expect 92L to stay in the Caribbean until it reaches near Jamaica and the Cayman Islands then moves NW-NNW into the Gulf I will be keeping an eye for some possible redevelopment within the next 5-7 days
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Quoting clwstmchasr:

KMan - I wasn't laughing at the time.


Could have been worse eh ?. I would have got up from that table.
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1103. Patrap
But my fav for sure..


"Lighten Up Francis"..
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1102. Patrap
Classic stuff there too..

LOL
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Quoting TampaSpin:


Kman.......does it look like the Sheer is trying to relax some also.....it does to me at the end.


The map shows the tendency has been falling for the last 24 hours but when it falls to 30 or 40 Knots from values above that it is really academic IMO. Nothing is going to get going in 40 knots.

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Quoting CaicosRetiredSailor:


http://moe.met.fsu.edu/~acevans/models/ep022010.pngLink

Thanks!
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All ways one better you are the man.
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1096. Patrap
What kind of training soldier?

Invest tracking Training ,..Sir!!!
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1094. xcool
hey all
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Quoting gordydunnot:
Do we really have enough data on shear and what causes it to be using past data to formulate how and what cause it,just asking.


With wind shear, you have to look at it day by day (synoptic time scale) and also you have to look at its trend the whole season when the seeason is over (climate time scale)

On a synoptic time scale, shear in the tropics is caused when an upper trough in the mid-latitude westerlies produced upper westerlies that oppose the tropical easterly trade winds. Sometimes, they get cut-off from the mid-latitude westerlies (stall) and constantly produce shear (like the TUTT in the Caribbean we've been talking about) when a deep-layered ridge amplifes to the northwest of it. During hurriacne season, upper troughs take further south tracks in June and November because the westerly polar jet is furthest south. The westerly polar jet is even further south during winter, and is furthest north during summer. The same can be said for the ITCZ.

On a climate time scale, El Nino increases shear and La Nina decreases shear. If you take time the average shear over the entire season during El Nino, you'll find its higher in the Atlantic.
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Quoting zoomiami:


Not too bad at home - rained a lot at the office though. That's one of the funny things about afternoon rains - it can be monsooning on one side of the street & dry on the other.

How about you? Did you get the rains.
We've gotten a.m. rains the last couple of days - really weird, and hot / humid making..... Today was more like July - hot all day, with light to moderate easterlies. So far we haven't gotten into the normal mid afternoon rain pattern as yet.
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Quoting clwstmchasr:


Or in my case last night when I had black jack three times and all three times the dealer had it as well.


LOL
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1090. Patrap
Hate to do movie quotes not, but when they asked private Murray where 92L was his response was blown up sir!!!.

Dats a fact,..Jack
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1089. pottery
Quoting johnnyascat:
post #1067 is below average, too. When I was reading Jeff Masters blog this past spring I seem to remember both Ossqss and TampaSpin posted regularly. So one explanation given does not seem to fit for these two posters. That leaves me thinking that this really is not a place for me to communicate with others through this post feature. I am inclusive by nature and censorship in any form is disgraceful imo. Especially when the posts have direct meaning to the purpose of this forum.

Methinks you make much, of little.
But, suit yourself.
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The GOM is safe for the next 144 hours, the CMC and GFS have declared it so :)

The EPAC, thats a whole other story.
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Hate to do movie quotes not, but when they asked private Murray where 92L was his response was blown up sir!!!.
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Quoting pottery:

What have you done to the EARTH??!!


LOL i made it an EGG head just like the Egg head that just LOL about the sheer.......Smart A-s i guess....LOL
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Quoting StormGoddess:
Hey there guys. Do we have a good projection map for the new depression in the Pacific yet?


http://moe.met.fsu.edu/~acevans/models/ep022010.pngLink
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post #1067 is below average, too. When I was reading Jeff Masters blog this past spring I seem to remember both Ossqss and TampaSpin posted regularly. So one explanation given does not seem to fit for these two posters. That leaves me thinking that this really is not a place for me to communicate with others through this post feature. I am inclusive by nature and censorship in any form is disgraceful imo. Especially when the posts have direct meaning to the purpose of this forum.
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I have posted my daily blog update. Please read and comment. It is greatly appreciated. Thanks!
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hey guys what I find funny is thst 92L has a higher 850 vort than TD2-E92L is not dead yet

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Quoting kmanislander:


The remnants of 92L are now in about 30 to 40 knots of shear. It has been falling but not to values that would allow regeneration any time soon.


Kman.......does it look like the Sheer is trying to relax some also.....it does to me at the end.
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1079. pottery
Quoting TampaSpin:


That is one big storm system in Central Africa....WOW! That might be trouble down the road!

What have you done to the EARTH??!!
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1077. Patrap
Woooosh,,,,,,,,,,,,,,,,,,,,,,,,,,,,



92L Floater - Water Vapor Loop
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1076. Greyelf
Re - 1062:

Feel free to change your filter to "Show All" and your panties might unbunch some.

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That is one big storm system in Central Africa....WOW! That might be trouble down the road!
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AOI

AOI

AOI

AOI

TS BUSTED FORECAST ALIBI
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Quoting TampaSpin:



I may be wrong but, it looks like sheer near 92L is trying to relax some....???


The remnants of 92L are now in about 30 to 40 knots of shear. It has been falling but not to values that would allow regeneration any time soon.
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1072. pottery
Quoting johnnyascat:


Is it the minus sign that does this? I never hit the minus sign so I guess that it is others who hit it huh? If true then other people are censoring the blog for me? This doesn't seem very fair or friendly. Did everyone here know that if you do not log in that these posts are not shown and there is no way to show them? That is why I created a log in. I was curious and I wanted to find out. If there are knowledgable people in here right now some answers would be nice if possible.

I am really not sure how the thing works.
It MAY have to do with people having other posters on "dont show".
That's why I have 'show all', and I dont use the - or + sign. But I have used the ! sign for objectionable posts (in my opinion they were objectionable).
It would be wrong for my opinion to affect your choice, I agree!
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Quoting TampaSpin:



I may be wrong but, it looks like sheer near 92L is trying to relax some....???


Imo, no way. Those clouds to the west of 92L are blowing right toward it, this clearly marks the southwesterly upper winds shearing it.
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Do we really have enough data on shear and what causes it to be using past data to formulate how and what cause it,just asking.
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It's kind of like playing cards. If you have a 10, Jack, Queen, King and a 3 you dont have a straight !. All it takes is for one to be missing

I manage that one all the time....
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Quoting stormpetrol:


Hi Kman, Hope all is well, best post I seen in a long time, I personally thought it might have been a TD, but who am I to argue with those that make the call, like you said they might revisit it after the Season is over or might not , it really doesn't matter, time to move on and be prepared, gotta a feeling come July to September many will be singing a different tune!


Hi there neighbour,

Yes, all is well but with the heat index near 115 F every day for three weeks now I am very concerned about peak season.

Water temps are near 86 F in the NW Caribbean and if this keeps up may well hit the 90s soon
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I may be wrong but, it looks like sheer near 92L is trying to relax some....???
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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.