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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As you may be right...i dont even want to think about that
Good afternoon
456, what happened to our invest?
Good afternoon 456!
Where would you put the COC right now.
That's an interesting reading; do other buoys in the area show commensurately high readings? Or is this due to heating from the oil trapping energy?
Wonder what we'll see in July, or even August?
INC157-171-142115-
/O.NEW.KIND.TO.W.0018.100614T2033Z-100614T2115Z/
BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
433 PM EDT MON JUN 14 2010
THE NATIONAL WEATHER SERVICE IN INDIANAPOLIS HAS ISSUED A
* TORNADO WARNING FOR...
CENTRAL TIPPECANOE COUNTY IN WEST CENTRAL INDIANA...
NORTHEASTERN WARREN COUNTY IN WEST CENTRAL INDIANA...
* UNTIL 515 PM EDT
* AT 431 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
SEVERE THUNDERSTORM CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS
STORM WAS LOCATED 7 MILES SOUTHEAST OF OXFORD...OR 14 MILES
SOUTHEAST OF FOWLER...AND MOVING EAST AT 25 MPH.
* THIS DANGEROUS STORM WILL BE NEAR...
SHADELAND AROUND 455 PM EDT...
PURDUE UNIVERSITY AND WEST LAFAYETTE AROUND 500 PM EDT...
LAFAYETTE AROUND 505 PM EDT...
DAYTON AROUND 515 PM EDT...
THIS INCLUDES INTERSTATE 65 BETWEEN MILE MARKERS 164 AND 178.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
TAKE COVER NOW. MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF A
STURDY BUILDING. AVOID WINDOWS. IF IN A MOBILE HOME...A VEHICLE OR
OUTDOORS...MOVE TO THE CLOSEST SUBSTANTIAL SHELTER AND PROTECT
YOURSELF FROM FLYING DEBRIS.
TO REPORT SEVERE WEATHER...CONTACT YOUR NEAREST LAW ENFORCEMENT
AGENCY. THEY WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE
IN INDIANAPOLIS.
&&
LAT...LON 4046 8671 4028 8674 4036 8710 4038 8710
4037 8712 4041 8729 4049 8725 4049 8711
4055 8711 4055 8710
TIME...MOT...LOC 2033Z 290DEG 23KT 4046 8713
$$
JH
Nope. It's been a WUWU the whole time.
EP92 seems more organized?
yeah! i was so sure it would have been a tropical depression this afternoon,i guess that may not even happen now.
Here's a link showing nearby reports:
Link
It's also dealing with a weak upper inverted trough riding south of the equatorial ridge, which earlier (image below is from 9z) was cutting off outflow and punching some dry air into the south side of the system. Outflow is still restricted on that side, but the trough is no longer well-defined.
NWUS53 KLOT 142031
LSRLOT
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL
331 PM CDT MON JUN 14 2010
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0308 PM TSTM WND DMG 2 ESE BOSWELL 40.51N 87.35W
06/14/2010 BENTON IN EMERGENCY MNGR
BARN DESTROYED...TREES DOWNED IN LOCATION OF TIGHT
ROTATION ON RADAR...POSSIBLE TORNADO DAMAGE.
&&
$$
IZZI
everything about this system is unusual lol
I found near 90 at 2 other buoys along the northern GOM. I didn't check the buoys near peninsula Florida yet.
Checking west Florida buoys...mid-upper 80's.
That convection is the north end of a tropical wave interacting with an upper-level low in the western Gulf of Mexico, but the upper low makes things unfavorable for development at this time. Will have to watch for persistence (if a surface low develops after the upper low diminishes, right now not a big deal.
Do you think that invest 92 will make some kind of comeback?
One that tries to develop for days and days, not strong enough to make that jump, but not weak enough to just go away
then it finds the right conditions and boom
Do you think this might be temporary and will make some kind of comeback, or will this possibly be the end of invest 92?
Good movie :) I enjoyed it.
I think it has a chance to build some convection once it gets west of 46W, but until then it will continue to struggle. It has lost energy in the form of restricted outflow to the south and complete separation from the ITCZ, as well as cooler SSTs. We will have to see how wel it battles the TUTT as it travels west, before the equatorial ridge is able to push the TUTT north in a few days.
I'm NE of Indianapolis, in Muncie. If it keeps together when it gets near this area, I'm going to hunt for it.
There is a flash ap now.
I've seen uglier! A little convection near center (NE), but nothing to write home about. Looks like you beat me by a couple of hours again!
What about those of us who dont live on the gulf coast. Dont you hope we will be spared too?
That's what I'm seeing too (thanks for the link, RobbieLSU)...anomalous to some degree, I would guess...a hot spot
it seems like it
I'd be agreeing with you, but right now, the evolution of the upper atmosphere thousands of miles west of 92L is getting less favorable by the day.
The persistent 200 mb anticyclone in the Gulf of Mexico has moved eastward into the western Atlantic, but to the south of that anticyclone, a mid-oceanic upper trough has linked up with our Caribbean TUTT to make a massive TUTT starting in the Caribbean, extending northeastward for several hundered miles. 92L is moving into shear generated by the TUTT, and can't develop thorugh the Caribbean Sea if things stay status quo.
Now add that upper low that has developed in the Gulf of Mexico, there is more westerly shear for it even there. Nope, don't see 92L coming back later.
No problem. I used to work at the NDBC. I just contacted someone who still works there to see if it's actually a hot spot or if it is a malfunction. I'll let yall know when they get back to me.
You're looking at current conditions but failing to look into the future. The equatorial ridge will be eventually building in and forcing the TUTT north of the Caribbean in a few days. By the time 92L reaches the islands, most of the Caribbean will be under marginally favorable upper winds, as the equatorial ridge will extend over most of the MDR and the subtropical jet will be pushed north of 20N.
I dunno about that...
I wonder if there is oil on the sea temp sensor, though it is supposed to be a meter down.
That is almost 309 Kelvin.
Not close on the latest SST plots:
More like 86 to 89 F.
But, winds have died down:
and are clearly inversely correlated:
But, I still question that. All other water temps in the gulf are only approaching 90, except coastal places where the water is very shallow (larger diurnal cycles).
Nahh Florida is use to getting Hurricanes...Thats why the best college team in the state is named after them....Lol Jk :)
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