Unusually well-organized 92L disturbance may become a tropical depression

By: Dr. Jeff Masters , 2:14 PM GMT on June 14, 2010

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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

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Quoting IKE:


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's what I'm seeing too (thanks for the link, RobbieLSU)...anomalous to some degree, I would guess...a hot spot
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1140. gator23
Quoting louisianaboy444:
I know all the ingredients are there and all that hype but wasn't 2009 suppose to be an active season...and i know what you will say...El Nino yes i know that as well as anyone...and i know there isnt much of a spot for divine intervention in Meteorology but if there is a gracious God hopefully the Gulf Coast will be spared this year...I have visions of all that oil getting pushed inland..


What about those of us who dont live on the gulf coast. Dont you hope we will be spared too?
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Last visible image of the day:

Member Since: September 2, 2009 Posts: 130 Comments: 21194
1138. 900MB
Quoting IKE:
Water Vapor of 92L....



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!
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1135. Levi32
Time to say goodnight as sunset approaches. Shallow thunderstorms are going up near the center, but do not look explosive.

Member Since: November 24, 2005 Posts: 635 Comments: 26685
iPad is great, it's just a pity we can't run any loop on it :(

There is a flash ap now.
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Quoting MrstormX:


Do you have work? If you don't I know where I would be driving; just head up Northwestern, pop on 52 and before you know it... twister!


I'm NE of Indianapolis, in Muncie. If it keeps together when it gets near this area, I'm going to hunt for it.
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1132. Levi32
Quoting Caribbeanislands101:

Do you think that invest 92 will make some kind of comeback?


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.
Member Since: November 24, 2005 Posts: 635 Comments: 26685
1131. IKE
Water Vapor of 92L....

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looks like 92L is dealing with some shear from the east ??? but thunderstorms are what looks to me beginning to refire near center .
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Quoting Hurricanes101:
92L very well could be another Dolly-type system

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
The only favorable conditions I could find is if it continues WNW/NW motion towards the Bahamas region. There it should have no problems intensifying.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
1128. Levi32
Quoting MiamiHurricanes09:
Hey Levi, how was Ironman 2 last night?


Good movie :) I enjoyed it.
Member Since: November 24, 2005 Posts: 635 Comments: 26685
Quoting Weather456:
RGB imagery shows the center of circulation near 10.5N 41.1W. It appears somewhat closed but the overall appearance of 92L has degraded due to evident southerly shear.

Do you think this might be temporary and will make some kind of comeback, or will this possibly be the end of invest 92?
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92L very well could be another Dolly-type system

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
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Quoting Hurricanes101:


everything about this system is unusual lol
That's true, lol.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Levi32:


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.


Do you think that invest 92 will make some kind of comeback?
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RGB imagery shows the center of circulation near 10.5N 41.1W. It appears somewhat closed but the overall appearance of 92L has degraded due to evident southerly shear.
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Quoting TexasHurricane:
Does this bear watching?



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.
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1121. IKE
Quoting Floodman:


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?


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.
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Quoting Weather456:
Satellite appearance shows 92L is feeling the effects of some southerly shear which is rather unsual.


everything about this system is unusual lol
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000
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


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1117. Levi32
Quoting Weather456:
Satellite appearance shows 92L is feeling the effects of some southerly shear which is rather unsual.


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.

Member Since: November 24, 2005 Posts: 635 Comments: 26685
haha don't bash me too hard guys i know what i'm saying is going against conventional science and Meteorology right now i'm just trying to be positive in what can be a very bad situation for all of the Atlantic but especially the Gulf with all that Oil can you imagine what that would do for the environment
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Quoting Floodman:


That's an interesting reading; do other buoys in the area show commensurately high readings? ?


Here's a link showing nearby reports:

Link
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Hey Levi, how was Ironman 2 last night?
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Weather456:
Satellite appearance shows 92L is feeling the effects of some southerly shear which is rather unsual.

yeah! i was so sure it would have been a tropical depression this afternoon,i guess that may not even happen now.
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EP92 seems more organized?
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Quoting stillwaiting:
My latest blog entry on 92L,was it a TD for a short time????

Nope. It's been a WUWU the whole time.
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Is it that time of the year again? :)
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I'm thinking 93L within24hrs from the wave that exited africa yesterday looks like a anti-cyclone forming over it!!!
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TORNADO WARNING
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
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Quoting IKE:


That's incredible...that's buoy 42040...64NM south of Dauphin Island,AL....

Water Temperature (WTMP): 95.9 °F


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?
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1105. 900MB
Quoting Weather456:
Good afternoon


Good afternoon 456!
Where would you put the COC right now.
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Satellite appearance shows 92L is feeling the effects of some southerly shear which is rather unsual.
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Quoting Weather456:
Good afternoon

456, what happened to our invest?
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Had to change my post to aren
Quoting Weather456:
Good afternoon


Good afternoon
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Quoting KEEPEROFTHEGATE:
93L is not to far away there is something special about this season that may even make 2005 look not as special anymore


As you may be right...i dont even want to think about that
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Quoting Weather456:
Good afternoon


Good afternoon! 92L not looking so good right now.
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1099. IKE
Quoting NCHurricane2009:


That SHIPS model was pretty ridiculous to begin with, no way this thing was ever going to become a hurricane with shear ahead of the system. Right now, 92L is beginning to approach that band of shear we've been talking about for the last few days. At this point, I feel 30% chance this thing will become TD1, 5% chance this thing will become TS Alex in the next few days. 92L is running out of time.


I agree...I was stunned when SHIPS had this nearing 90mph. SHIPS is usually over on intensity of systems.
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1098. KEEPEROFTHEGATE (Mod)
Quoting Weather456:
Good afternoon
afternoon 456
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Quoting Weather456:
Good afternoon

Good Afternoon!!
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lousiana boy:who predicted a active year in 09',I though most were saying average????
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1095. Levi32
Quoting Weather456:
Good afternoon


Afternoon 456.
Member Since: November 24, 2005 Posts: 635 Comments: 26685
Good afternoon
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Quoting IKE:
SHIPS model keeps lowering the outlook for 92L. Two days ago it had it nearing a 90mph hurricane....



That SHIPS model was pretty ridiculous to begin with, no way this thing was ever going to become a hurricane with shear ahead of the system. Right now, 92L is beginning to approach that band of shear we've been talking about for the last few days. At this point, I feel 30% chance this thing will become TD1, 5% chance this thing will become TS Alex in the next few days. 92L is running out of time.
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Quoting KEEPEROFTHEGATE:
93L is not to far away there is something special about this season that may even make 2005 look not as special anymore
I agree.
Member Since: September 2, 2009 Posts: 130 Comments: 21194

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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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