Unusually well-organized 92L disturbance may become a tropical depression
Invest 92L, a remarkably well-developed African tropical wave for so early in the season, is midway between Africa and the Lesser Antilles Islands. Infrared satellite loops show a modest area of heavy thunderstorms along the north side of 92L's center of circulation, and the storm's heavy thunderstorms activity appears to be slowly increasing in intensity and areal coverage. Upper-level outflow is apparent to the west and north of 92L, and the outflow has been gradually improving this morning. Visible satellite loops do not show much in the way of low-level spiral bands, and my current take from the satellite imagery is that 92L is slowly organizing, and will not become a tropical depression any earlier than 11pm EDT tonight (Monday.) A 4:27 am EDT pass from the WINDSAT satellite saw a partially closed circulation at the surface (open on the south side), with top surface winds of 25 - 30 mph north of the center.
Figure 1. Morning satellite image of Invest 92L (left side of image) and a vigorous new tropical wave that has moved off the coast of Africa (right side.) None of models develop the new tropical wave, but it bears watching.
Sea surface temperatures
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°C, and will increase to 29°C by Thursday. 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.)
Dry air not a problem for 92L until Wednesday
The disturbance doesn't have to worry about dry air today or Tuesday--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 200 - 300 miles from any substantial areas of dry air. As 92L continues to push northwest, though, the SHIPS model is predicting that relative humidity at middle levels of the atmosphere will fall from the current value of about 70%, to 60% on Wednesday. This dry air may begin to cause problems for 92L on Wednesday, especially since wind shear will be increasing at the same time. Tropical cyclones are more vulnerable to dry air when there is substantial wind shear, since the strong winds causing the shear are able to inject the dry air deep into the core of the storm.
Madden-Julian Oscillation
The 60-day cycle of enhanced thunderstorm activity called the Madden-Julian 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.
Wind shear
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 was located near 10°N, 40°W at 8am EDT this morning, a few hundred miles south of this band of high shear, and is currently only experiencing 5 - 10 knots of shear. This low amount of shear should allow for some steady development of 92L over the next two days as it tracks west-northwest or northwest at 15 mph. The latest run of the SHIPS model is predicting the shear will rise to 20 knots on Wednesday, which may start to cause problems for 92L.
The forecast for 92L
The National Hurricane Center is giving 92L a high (60% chance) of developing into a tropical depression by Wednesday morning, which is a reasonable forecast. The odds of development have increased since yesterday, as the storm has moved considerably to the northwest, away from the Equator. Now it can leverage the Earth's spin to a much greater degree to help get it get spinning. It is quite unusual for a tropical depression to form south of 8°N latitude.
I expect that 92L's best chance to become a tropical depression will come on Tuesday, and the storm could strengthen enough by Wednesday to be named Tropical Storm Alex. The farther south 92L stays, the better chance it has at survival. With the system's steady west-northwest movement this week, 92L will probably begin encountering hostile wind shear in excess of 20 knots by Wednesday, which should interfere with continued development. Several of our reliable models do develop 92L into a tropical storm with 40 - 55 mph winds, but all of the models foresee weakening by Thursday or Friday as 92L approaches the Lesser Antilles Islands and encounters high shear and dry air. I doubt 92L will be anything stronger than a 45 mph tropical storm when it moves through the northern Lesser Antilles Islands on Friday and Saturday, and it would be no surprise if wind shear has destroyed the storm by then. However, as usual, surprises can happen, and the GFS and the SHIPS model (which is based upon the GFS) do indicate that more modest levels of wind shear in the 15 - 20 mph range late this week may allow 92L to stay stronger than I'm expecting. 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 as early as Thursday night.
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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No
always pay attention to who is doing the RIPs and where they live respectively to where the storm is forecast to go
thats all i'll say. watch for yourself and listen to the SKILLED peeps on here
:)
It's on-base percentage was rather low so he was moved lower in the batting order.
LOL!
I doubt it....seriously doubt it.
Updated: 1 hr 10 min 45 sec ago
89 °F
Mostly Cloudy
Humidity: 63%
Dew Point: 75 °F
Wind: 5 mph from the NW
Pressure: 29.91 in (Steady)
Heat Index: 99 °F
Visibility: 10.0 miles
UV: 6 out of 16
Pollen: 5.40 out of 12
Pollen Forecast new!
Clouds: Scattered Clouds 2800 ft
Mostly Cloudy 6000 ft
(Above Ground Level)
Elevation: 16 ft
Quote some of the terrible grammar and spelling on this blog not the stuff that's right!!
LMAO
they keep it at 60%
to me thre is absolutely no reason to give it a higher or lower percentage
very funny you know?
I consider myself pretty skilled since I have been doing this for quite awhile professionally and I will RIP it. I got jumped on again for thinking 3 days ago it had no chance and if it made anything only a TD for maybe a day. Same thing with 90L but oh well. Looking forward to th next wave. Looks pretty good but might run into similar troubles. I live right on the coast in the Gulf as well.
Ewwwwwww! One ton tar ball found off Perdido Pass (Alabama/Florida Line)
Link
I thought they would up it on the last TWO, but they kept it at 60%.
I think they'll say it's diminished some since the last advisory and lower the pct. to 40 or 50%.
LOL......
Goodnight.
I remember you getting jump on...you and stormtop, under his new screen-name.
At least you held your ground! Props!
did you put a down payment on that, can you get a refund,,, don't R.I.P 92L until the NHC does.
That just seems kind of stupid to RIP something unless it is actually dead and gone, and 92L clearly is not
I really think it is just a waste of a post to me
Anyway I am conflicted with 92L, I see these loops and think this is a TD, especially considering the systems that were named last season.
yep yep you said it all
Truth be told i bet everyone of the so called casters here would jump at a chance to work for the NHC.
On the other hand it does a funny read at times.
Should be Yellow at 30% but, they won't drop it that fast.....so orange 40-50% probably.
50%
50%
The code red will stay the same, 60%
Crow a-la-orange.
Seems most likely. Although it has lost organization not just lacked in gaining it.
Ok, what percentage do you guys think that the NHC will give to 92L in the next TWO? The winner(s) gets a cookie.
Thanks...hey I can be wrong too haha. But I truly believe that flip floping on your forecast does more harm than good. I got to say there were some great points which really had me leaning and it did look impressive. Problem is there were a lot of mid clouds and not as much convection as some may have thought. Who knows it may still have a chance but it might hit a wall. I just hope everyone remembers it is still really really early. We will have 1, 2 or 15 to chase this year.
BAM MOdels.......SOUTH 92L goes....OH NO!!! NOT GOOD!
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