First tropical depression of the season may form from 92L
An unusually large and well-developed African tropical wave for so early in the season has developed midway between the coast of Africa and South America. The storm was designated Invest 92L by the National Hurricane Center yesterday, and has a good chance of becoming the first tropical depression of the Atlantic hurricane season. Surface winds measured by the 8:23am EDT pass of the European ASCAT satellite revealed that 92L already has a closed surface circulation, though the circulation is large and elongated. Top winds seen by ASCAT were about 25 mph. METEOSAT visible satellite loops show a large and impressive circulation that is steadily consolidating, with spiral bands building inward towards center, and upper-level outflow beginning to be established to the northwest and north.
Figure 1. Morning satellite image of Invest 92L.
Climatology argues against development of 92L, since only one named storm has ever formed between Africa and the Lesser Antilles Islands in the month of June--Tropical Storm Ana of 1979 (Figure 2). However, sea surface temperatures (SSTs) underneath 92L are an extremely high 28 - 30°C, which is warmer than the temperatures reached during the peak of hurricane season last year, in August - September. In fact, with summer not even here, and three more months of heating remaining until we reach peak SSTs in the Atlantic, ocean temperatures across the entire Caribbean and waters between Africa and the Lesser Antilles are about the same as they were during the peak week for water temperatures in 2009 (mid-September.) While 92L will cross over a 1°C cooler patch of water on Monday, the storm will encounter very warm SSTs of 28-29°C again by Tuesday.
The disturbance doesn't have to worry about dry air--Total Precipitable Water (TPW) loops show a very moist plume of air accompanies 92L, and water vapor satellite loops show that the center of 92L is at least 300 - 400 miles from any substantial areas of dry air. The 60-day cycle of enhanced thunderstorm activity called the Madden-Jullian Oscillation is currently favoring upward motion over eastern tropical Atlantic, and this enhanced upward motion helps create stronger updrafts and higher chances of tropical cyclone development.
Figure 2. Tropical Storm Ana of 1979 was the only June named storm on record to form between Africa and the Lesser Antilles Islands.
The forecast for 92L
A major issue for 92L, like it is for most June disturbances, is wind shear. The subtropical jet stream has a branch flowing through the Caribbean and tropical Atlantic north of 10° N that is bringing 20 - 40 knots of wind shear to the region. Our disturbance is currently located at 7°N, well south of this band of high shear, and is only experiencing 5 - 15 knots of shear. This moderate amount of shear should allow for some steady development of 92L over the next few days as it tracks west-northwest at 10 - 15 mph. The National Hurricane Center is giving 92L a medium (30% chance) of developing into a tropical depression by Tuesday morning. Based on visible satellite imagery over the past few hours, I believe this forecast is not aggressive enough, and that 92L has a 50% chance of developing into a tropical depression by Tuesday morning. Another factor holding 92L back is its proximity to the Equator. I would give 92L higher chances of developing if it were not so close to the Equator. The system is organizing at about 7°N latitude, which is so close to the Equator that it cannot leverage the Earth's spin much to help it get spinning. It is quite unusual for a tropical depression to form south of 8°N latitude.
The farther south 92L stays, the better chance it has at survival. With the system's steady west-northwest movement this week, 92L should begin encountering hostile wind shear in excess of 30 knots by Thursday, which should be able to greatly weaken or entirely destroy the storm before it gets to the Lesser Antilles Islands. However, residents of the islands--particularly the northern Lesser Antilles--should follow the progress of 92L closely, and anticipate heavy rains and high winds moving through the islands by Saturday or Sunday next weekend. The GFDL and HWRF models are predicting that 92L will develop into a moderate strength tropical storm that will then be weakened or destroyed by the end of the week, before it reaches the islands. This looks like a reasonable forecast.
Figure 3. The departure of sea surface temperature (SST) from average for June 10, 2010. Image credit: NOAA/NESDIS.
Oil spill wind forecast
There is little change to the oil spill wind forecast for the coming two weeks. Light winds of 5 - 10 knots mostly out of the south or southeast will blow in the northern Gulf of Mexico all week, according to the latest marine forecast from NOAA. These winds will keep oil near the coast of Louisiana, Alabama, Mississippi, and the extreme western Florida Panhandle, 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.
Jeff Masters
Reader Comments
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Well, what credentials would you expect from a 12 y/o kid? There's your answer.
My point was they are leaning NW....previous language was solely WNW.
Anyone for what we saw in 2008 with 3 storms at the same time?
I struggled with working everything else during the insane periods with more than 2 storms.
Well problem is that peeps want our 1st TD and 1st TS of the season and are jumping to conclusions and excitement over not looking @ the data correctly. Emotions are over-running their knowledge and performance. Alot of people ingore or call people trolls like you said cause they downcast or just are telling the facts of what's really happening.
I dont come on here alot so some dont know me.. some do. I come on..tell peeps whats going on..then get into a challenge with the dreamcasters. Then they see later why something doesnt develop and says the NHC should/could of before it broke up. Back to basic step 101. Development of a Tropical system without excitement needs to be put into place.
They have to account for either motion they have their hurricane models wanting to take this NW
2010 is showing its true colours early.
lol I think hes 16 or 17 but close enough
Yes which of course they respect a great deal, and so their forecasts like to lean in their direction, or at least include their solutions.
Ah I know why - got a problem with Google Chrome. A quick look on IE8 shown it.
Why are you using the EWP?
hmm I was wrong.. he is 13 then
Precisely
Either last year or '08 (prolly '08, cuz I remember us talking about how CMC wasn't so crackified last year....)
???
I think a lot of us will have to practice controlled multitasking a few times this season with multiple storms in progress.
Theres nothing wrong with us kids.
I agree lol :)
Note: PDF files
http://www.nhc.noaa.gov/pdf/nhc_new_2010.pdf
"Effective May 15, the National Hurricane Center will implement important changes in some of its text and graphical products. It will also make some additions to its Web site and experimental products. This is part of a continuing effort at the National Hurricane Center to expand and enhance its level of service."
And a users guide if you would like to check it out.
National Hurricane Center Product Description Document: A Users Guide to Hurricane Products
February 2010 Department of
Nevermind.
This Joey's Dad from CC High. I agree with you.
Are they just for 92L or for all storms? I didn't expect 92L to be on the US main land so soon.
Thank God for multiple monitors...
Why were you asking? I wasn't sure? Maybe something I don't know.
What all country's need is to stop the over-protection of kids on the internet and proper education on how to behave amongst people on the internet.
Invest 92-L Located In The Eastern Atlantic: If this is what the rest of this hurricane season holds, then it's going to be a very, very long and potentially dangerous season!! I am closely monitoring an area of low pressure, labeled Invest 92-L, which is located about 900 miles southwest of the Cape Verde Islands (8 North Latitude, 32.5 West Longitude). This tropical disturbance is nearing tropical depression status. Satellite imagery this morning showed Invest 92-L becoming better and better organized with each new satellite frame and I think it may be upgraded to Tropical Depression status by this evening or at the very latest early Monday morning. In fact, it may reach tropical storm strength (its name would be Alex) sometime during Monday.
Analysis of this system showed that environmental conditions are favorable for development and intensification as we have very warm sea surface temperatures, good outflow, plenty of moisture and low wind shear values. The latest model guidance is forecasting that the low wind shear values will continue for the next 2 to 3 days and thus they are forecasting 92-L to be a 50 to 70 mph tropical storm in about 3 to 4 days. After that, weakening is forecast by the model guidance due to increasing wind shear values as this system closes in on the Lesser Antilles in 6 days. My take is that we are looking at slow, but steady intensification over the next few days and I expect that we may be looking at a 50 mph tropical storm around Tuesday or at the latest Wednesday.
The latest model track guidance is showing a west-northwest track over the next 2 to 3 days. The model guidance may actually be a bit too far north in their forecast tracks. The reason why I think this is because currently there is a large trough of low pressure located near 50 West Longitude. This trough should lift over the next few days and this will give way to a ridge of high pressure. This weather pattern would favor a west-northwest track over the next several days and the consequences are that this system will be near the Lesser Antilles by about Friday. All interests in the Lesser Antilles should keep close tabs on this system.
It should be noted that the long range GFS model is forecasting plenty of activity across the Inter-Tropical Convergence Zone over the next 2 weeks. The combination of this, strong high pressure to the north and a diffluent wind flow aloft could lead to additional tropical cyclone development between the Lesser Antilles and the coast of Africa over the next 2 to 3 weeks. Also, satellite imagery this morning showed another strong tropical wave located over western Africa that should emerge in the eastern Atlantic over the next day or two. So, like I said at the beginning of this discussion, if this is what the rest of this hurricane season is going to be like, then strap in, because it's going to be one hell of a bad hurricane season!!
So, in closing, Invest 92-L looks better organized with each new satellite frame and with sea surface temperatures well above average and environmental conditions that are favorable; I would say development into a tropical depression is very possible by this evening or at the latest Monday morning, if it remains well organized.
One Last Item Of Interest: The annual Eastern US Weather Forums conference is being held this weekend in Baltimore, Maryland. Unfortunately, I could not attend; anyways, Stacy Stewart from the National Hurricane Center spoke yesterday and had some interesting comments.
They include:
His personal prediction of 17 named storms, 12 hurricanes and an Accumulated Cyclone Energy Index of 200 plus.
Very active early season, mid to late July. Also we may be looking at late and strong Caribbean and Gulf of Mexico systems due to very warm sea surface temperatures and also activity shifts west later in the season.
The Mantra at the NHC is GO SHEAR!
from rob lightbown
Like what we saw with Dean
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