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June hurricane season outlook; Bahamas disturbance fizzles

By: Dr. Jeff Masters, 3:12 PM GMT on June 16, 2007

An area of disturbed weather with heavy thunderstorm activity is over the Bahama Islands, and shows no signs of organization. The system crossed Cuba last night, brushed South Florida, and brought heavy rains of 2-4" inches over these areas. The system will bring another 1-2" to the Bahamas before heading northeast out to sea. The disturbance is now entering an area with very high wind shear of 30 knots, and is no longer a threat to develop into a tropical depression. The system could develop into an extratropical storm. No Hurricane Hunter missions are planned into the system, and NHC no longer thinks highly enough of it to offer their suite of early model tracks. There are no other threat areas to discuss, and none of the models are showing any new developments over the coming week. I'll repost my June hurricane season outlook below, and have a new blog on Monday!

Jeff Masters

Last half of June climatology
The last half of June is usually one of the quietest portions of hurricane season. In the 12 years since the current active hurricane period began in 1995, only four tropical storms formed in the last half of June. Thus, recent history gives us a 33% chance of a last-half-of-June named storm. None of those four storms since 1995 became a hurricane, and hurricanes are quite rare in June. Only one major hurricane has has made landfall in June--Category 4 Hurricane Audrey of 1957, which struck the Texas/Louisiana border area on June 27 of that year, killing 550. The primary breeding grounds for last half of June tropical storms is the western Gulf of Mexico (Figure 1).

Figure 1. Tracks of all tropical storms and hurricanes since 1851 that formed June 16-30. The western Gulf of Mexico is the preferred location for storm formation in late June. Interestingly, the eastern Gulf of Mexico sees the most early June storms.

Sea Surface Temperatures
Sea Surface Temperatures (SSTs) have remained about 0.5-1.0 C above average over the tropical Atlantic over the past two weeks. An area of cooler than average SSTs that surrounded Florida in early June has shrunk, and the entire Gulf of Mexico is now warmer than average. However, while SSTs are above normal, they are still far cooler than the peak temperatures that occur in August-October. This will limit the regions where tropical storm formation can occur this month to the Gulf of Mexico, Western Caribbean, and Gulf Stream waters just offshore Florida, where water temperatures are warmest (Figure 2). June storms typically form when a cold front moves off the U.S. coast and stalls out, with the old frontal boundary serving as a focal point for development of a tropical disturbance. African tropical waves, which serve as the instigators of about 85% of all major hurricanes, are usually too far south in June to trigger tropical storm formation.

Figure 2. Sea Surface Temperature (SST) departure from average for June 14, 2007. Image credit: NOAA.

Tropical Cyclone Heat Potential
It's not just the SSTs that are important for hurricanes, it's also the total amount of heat in the ocean to a depth of about 150 meters. Hurricanes stir up water from down deep due to their high winds, so a shallow layer of warm water isn't as beneficial to a hurricane as a deep one. The Tropical Cyclone Heat Potential (TCHP, Figure 3) is a measure of this total heat content. A high TCHP over 80 is very beneficial to rapid intensification. As we can see, there is less heat energy available this year than in 2005, which recorded the highest SSTs and TCHP ever measured in the tropical Atlantic. I expect that the TCHP will continue to remain below 2005 levels this year, so we should not see as many intense hurricane as we saw in 2005.

Figure 3. Tropical Cyclone Heat Potential (TCHP) for June 14 2005 (top) and June 14 2007 (bottom). TCHP is a measure of the total heat energy available in the ocean. Record high values of TCHP were observed in 2005. TCHP this year is still quite high, but lower than in 2005. Image credit: NOAA/AOML.

Wind shear
Wind shear is usually defined as the difference in wind between 200 mb (roughly 40,000 foot altitude) and 850 mb (roughly 5,000 foot altitude). In most circumstances, wind shear above 20 knots will act to inhibit tropical storm formation. Wind shear below 12 knots is very conducive for tropical storm formation. High wind shear acts to tear a storm apart.

Wind shear over the past 11 days (Figure 4, top image) has been above 20 knots over most of the breeding grounds for June tropical storms--the Gulf of Mexico, Western Caribbean, and Bahama waters. While the shear has been below average (Figure 4, bottom image), any wind shear above 20 knots is high enough to discourage tropical storm formation. This is very typical for June, when the jet stream is still very active and quite far south. The jet stream will gradually weaken as summer progresses, bringing lower wind shear and greater chances for tropical storm formation. The extreme southwestern Caribbean has seen shear below 10 knots, but no tropical waves or remains of old cold fronts have moved into this region to trigger tropical storm formation. The latest two-week forecast from the GFS model predicts that wind shear will be near normal levels across the Caribbean, Gulf of Mexico, and tropical Atlantic for the remainder of June.

Figure 4. Top: Average wind shear over the past 11 days. Wind shear is the difference in wind between 200 mb (roughly 40,000 foot altitude) and 850 mb (roughly 5,000 foot altitude) in meters per second (multiply by two to get the approximate wind shear in knots). In most circumstances, wind shear above 20 knots (10 m/s, the blue colors in the top image) will act to inhibit tropical storm formation. Wind shear below 12 knots (6 m/s, the orange colors) is very conducive for tropical storm formation.
Bottom: Departure of wind shear from average for the past 11 days in meters per second. Note that wind shear has been below average over most of the tropical Atlantic and Gulf of Mexico over the past 11 days.

Dry air and African dust
It's too early to concern ourselves with dry air and dust coming off the coast of Africa, since these dust outbreaks don't make it all the way to the June tropical cyclone breeding grounds in the Western Caribbean and the Gulf of Mexico. Developing storms do have to contend with dry air from Canada moving off the U.S. coast, though.

Steering currents
The steering current pattern for the first half of June featured a pattern much like we saw in 2006, with an active jet stream bringing many troughs of low pressure off the East Coast of the U.S. I expect this pattern to continue for the remainder of June, and the troughs should be frequent enough and strong enough to recurve any tropical storms of hurricanes that penetrate north of the Caribbean Sea. Steering current patterns are not predictable more than about two weeks in advance, and there is no telling if we are in for a repeat of the favorable 2006 steering current pattern that recurved every storm out to sea. It is encouraging to note that in 2006 the steering current pattern locked into place in late May and stayed that way for almost the entirety of the hurricane season. The atmosphere often stays locked in to a particular steering pattern for an entire summer.

Recent history suggests a 33% chance of a named storm occurring in the second half of June. Given that the current SST pattern and two-week wind shear forecast look fairly typical for June, I'll go with a 30% chance of a named storm forming during the last half of June.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

The Florida Panhandle needs a good dousing of rain still. any hope anytime soon went to storm junkies page and i seen the gfs forecast model and had no clue where it was originating from but any rain would be highly welcomed.
Good evening. Here at 11n 61 w-
Temp 79f
Dew pt. 73 f
pressure 29.95 ( rising )
Time 9;30 pm
Forecast for the week is similar

Accumulated June rainfall 157 mm ( aprox 6 inches )
Apparently, the forecasters see nothing in the wave east of here, to concern them.
interesting tropical wave. could be a wet wed for the wondwards

href="http://www.ssd.noaa.gov/goes/east/catl/loop-rgb.html" target="_blank">Link
......and the Windwards as well, LOL
interesting tropical wave, heading for the sw winwards

Hi stoormfury.
See my post of a few mins. ago. The local Mets here dont seem to think that wave will have much rain in it, but I would not be suprised if we get some. I'm in Trinidad.
This is my website i am not asking you to forcing you or pushing you to join but just to See if it is Good or Terrible
My site:
i expect some moderat rain here in St LUCIA by wed. the wave has a northerly component to it. there is even some cyclonic turning at the mid level.
Thanks, Pat. You see anything to be concerned about there ?
How are you doing.?
Its an interesting feature..a lil south and early though in my eyes. Nice evening to you.

N. Atlantic Imagery,Global Hemisphere views and more.

The pressure in the gulf is oppressively high so I do not know it the rain will make it though the night. But if you look along the trough in the GOM there are two areas of rotation one about 200 miles north of the eastern tip of the Yucatan and another about 150 mi WNW of key west. (you can see that one a little on radar.) Both must be low/mid level because there doesnt seem to be any real surface low.

Thanks pat - Thats a nice storm coming off Africa.

The one near the windwards is not to shabby either.
yes a bit south, but not unusual. ana in 1970 formed in thid general area. wind ahear is forecast to decrease in the next few days.
Not too bad Wammybammy
Posted By: JFLORIDA at 2:16 AM GMT on June 18, 2007.

The pressure in the gulf is oppressively high so I do not know it the rain will make it though the night. But if you look along the trough in the GOM there are two areas of rotation one about 200 miles north of the eastern tip of the Yucatan and another about 150 mi WNW of key west. (you can see that one a little on radar.) Both must be low/mid level because there doesnt seem to be any real surface low.

Florida gets numerous thunderstorms all through the summer that are often steered and guided by subtropical or tropical ridges of high pressure, many places that get frequent areas of deep low pressure to the north of Florida receive only a fraction of what Florida sees from frequently hiher pressure.

To say whether storms will survive or not must not be based on air pressure, its much more complicated then just that.
Thank you - i hoped you guys like it
Night all,

Just an observation: the ITCZ may be hitting S. America still, but it's now hitting Guyana instead of N. Brazil. In a couple of weeks the northern half of the waves riding it will be hanging out into the Caribbean.

Trini should get some showers then . . .
I mean, like as in not self sustaining tropical lows over water. But still they could survive I guess.

Yea as a frontal system, even with shear over water, you are right.
That is a nice layout.
Hi Baha. It will be interesting also, to see if the wave east of here can maintain its features for 10 days or so, which may put it around 80 W.
We will have to watch that.
Just in case you missed My post:
Thanks you guys who have Gaven me advice and comments about my site

If you haven't seen the site,Let me make it clear befor you Go to the site that you Don't have to join,But sign the guestbox so i can always Remember you visted my site!
The site:
Appreciate your comments JFlorida.
Concerning the wave! Notice the thick Dust Plume racing west, pink areas (the darker the pink, the thicker the dust). This dust should overtake the area, and from the looks of it, dust should make it to the caribbean. IMAGE COPYRIGHT EUMASTAT2007!
Thats really cool TCW - oh and early congrats on the addition to your family.
Very handy tool JF! If you go to the main page and learn the air mass rules it is even better! Eumastat was developed to detect early organization and intensification in the MDR and various other areas. The dust feature is paramount in the meat of the season.

Thanks JF! Isabella is due July 10th! So Exited, can't wait! Of course my wife can't either.
Hey Hey Hey!!!

If you want to see a weird little show reminiscent of tropical form up zoom into the Yucatan on the loop. That storm going into Campeche is intense too. Isnt dissipating all that fast either.

I swear zooming in and rocking it it has counter clockwise CIRC.

The pressure is low around there too. ( around 29.85 ish by guestimate from the last reported PWSs)

Its getting late - Sombody else look at this!!!
I think y'all (Everyone on this blog) put too much confidence into the SAL. The bloody thing still isn't even proven to have any effect on the outcome of a hurricane season. Dust is not an inhibiting factor. Actually if you want to think about it... A large dust cloud in a moist place would probably enhance cloud formation due to the fact that it would provide an excess of nucli for water molecules to bond to. It is the dry air that goes along with most dust storms that wrecks hurricanes...
Good - Hellsniper223 look at Campeche!
lol JFLORIDA, Despite how much I would love to see something form down there... I don't think it will. But hey, if it stays persistent tomorrow then I may get excited. Anyways... It's really late. I need sleeeeeppp.... zzz...
nooo. ok well Ill watch it - it seems to be growing still.
Here is the water vapor.

Its in the right place on the front too even.


Bad link. :P
That Thunderstorm complex looks like an Afternoon thunderstorm that slid offshore and survived long enough to be effected by diurnal maximum. It'll probably be dead by 11AM tomorrow. :P
OK, but its got a surface circ AND a pressure dip - rock the IR at half speed and zoom in -- and, why is it propagating in a different direction?

Turning on the UL winds on this loop - could be the ULL in the western tip of the Peninsula?
BUT look at the cloud motion under the heavy convection - VERY counterclockwise.
well look at it BEFORE you make judgment. You guys have missed this whole system, and not just the basics; Every single part of it.

And also I said the rest of it was Frontal if you remember. I also said there was no surface lows OR circulation - So why did you feel the need to spread disinformation again JP?
Good find JF, I don't know what will become of it, there is some slightly dry air to the north and it may be just a t-storm. But, nothing is written in stone, we will know more tomorrow.
Jf I did notice a rotation though...you may be on to something...
Jflorida, it's a supercell just like hellsniper said. It is under low shear and upper level divergence. It's the best shot at anything that we've got right now, but I'd say less than 5%.
If it's still there at this time tomorrow, I'll revise my estimate.
I don't know...it is late, and I eally can't tell what is going on I am drunk off of water so...
then dont lose sleep. I don't even think half of you even know how to look for rotation . You all just parrot the NHC reports.

Did you look at the loop, No. Don't comment anymore.
Thats fine, a super cell is ok. But there is a surface low and some rotation.
Here we go... Just like Friday night...

I have noticed some rotation, but that remains to be seen if it is at the surface. Convection probably is being enhanced by the diurnal max. Tommorow, if it's still maintaining its convection in the worst time of day imaginable, then I'll worry about it. Until then, I'll just monitor it.
JF are you toasted?
raving about this thing that has done nothing.

No I said I was watching it, YOU said it all dissipated yesterday and tried to make it look like I was forecasting a major hurricane.

So now im high? You guys don't bring anything of value to this post. you just lurk and wait to ridicule others. Thats why everyone decent leaves in summer.
That's what I was thinking JP
It is most distressing that so many people are beginning to think that 2007 will be another wimpy year. First some people say there will be troughing like in 2006 all year, then some people say La Nia isn't going to develop, and even if it doesn't, doesn't mean you won't have an active season. And just cause June is quiet? Who cares? LOL
JF can you explain what "it" is? What are you referring to?
Personally, I don't think it will be an average year like 2006, I think there is a good chance a major hurricane could make landfall
2006 was classified as NORMAL and to already have exhausted 2 names with one out of season isn't considered that quiet...plus June is the quietest month of hurricane season it's not like it's September or something.
True JP same here...it could become tropical or it could dissapate and just be known as the daytime thunderstorms that moved into the GOM
Yeah jp, everyone needs to realize, June's always quiet... Except on rare occasions. And I bet that warming in the equatorial East Pacific is cause of a kelvin wave. Cooling will take place soon enough. A warm-bias neutral or El Nio looks extremely unlikely.

It is DEFINITELY not normal to have a storm everyday. I'm beginning to think some of the people on here WANT a storm, don't you think so, jp? I really do. The way they get mad at everything that isn't a report of an active season or major hurricane landfall... You get the picture. NOTE: This is NOT directed at you JFlorida. Not at all. But at people in general on these blogs.

At the same time, each time there is a report of something bad going to happen in the tropics, there are those who are quick to say "troughing". Wishcasting gets annoying.
not lossing any sleep tonight but the new blob off of africa anythoughts
JFlorida, please don't insult him. I understand how you feel. My family and I sometimes get mad at each other cause one of us likes to track storms, the other doesn't. It's sad. It's just weather. It's for us to enjoy, not argue over.
stormybil, where? Link me? Probably just a tropical wave that will be destroyed by wind shear and cooler SSTs.
here you go Link
Yea we were looking at that earlier stormybil, Theres a cool link a few posts down a perspective sat with it coming off Africa. Ill look for it.
and no strom is the same we learn here from every new one that pops up . and these days that can happen at any hour , stay tuned
one little thunderstorm but not every little thunderstorm becomes a troical system

What??? Ive actually had college meteorology, not the easy one either. But see, none of you have even looked at and analyzed the loop seriously and we are in just another ego match, AGAIN. Forget I said anything.
stormybil, SSTs are marginal, but not exactly precise for tropical cyclogenesis. The wave is a bit far south for me to think much of it, but rest assured, I WILL WATCH IT FOR YOU! Also, I think the recent cooling of the GoM is attributed to a kelvin wave, perhaps? I don't know ALL the mechanics of a kelvin wave, but I do know some. Is it possible equatorial East Pacific SSTs could warm, while the GoM cools cause of kelvin wave activity?

What if the upper-level circulation works its way to the surface? Then what? Or at least the mid-levels by earlier today?

JFLORIDA, seriously calm DOWN. jp is RIGHT when he says not everyone will agree with you. That is what makes us different. We are PEOPLE, each with our own likes/dislikes/agreements/disagreements. GET USED TO IT...
jp, thanks. Good night.
Yeah, I won't be concerned. Unless it keeps its identity this time tommorow. Then maybe.
JFLORIDA, seriously calm DOWN. jp is RIGHT when he says not everyone will agree with you. That is what makes us different. We are PEOPLE, each with our own likes/dislikes/agreements/disagreements. GET USED TO IT.

No, you guys gang up on people and railroad others out of discussions, and that is wrong.
I haven't ganged up on you. I try and treat everyone equally. I love to make peace with people on here.
I shouldnt have even asked them anyway. They are too cool to be enthusiastic about anything. Asking if I was high was the final straw. I dont know why people in groups and clicks think that they can be continuously disrespectful and expect you not to call them out for it.

Anyway, I apologize for wasting so much blog space on them though, that wont happen again.

Checking back - If there is a strong surface low in Campeche
Its near the shore or just on shore. The Buoy is just showing a dip in pressure. Many of the PWS in the area are not updating properly. The entire system seems to be lifting to the NNW (by the outline of the high) but that will probably turn towards the NNE in a bit.

Its difficult to tell whats going on at the surface because of these intense storms.

The storm coming off Africa is hot; it died a little and then started building again. The system in the windwards is interesting too. The flow across the Caribbean is a little more favorable in a few was also, but, I think I remember reading the trades were a little unfavorable however.
Morning all ☺
Anyone else having trouble with the GHCC site? Can not seem to get it to load.
tropical wave heading for southern windwards.looks like a rainy day come wed.

I bring nothing to the table when it comes to this blog , but I sure learn alot. And pick up a bunch of awesome links along the way.

Sometimes Ill get replies, Sometimes I get ignored. That doesnt dicourage me though. I try to get in where I fit in but the chances of me fitting in are less than 10% (Due to the lack of weather forcasting skills)
But I still get in anyway. :P

It's a big ole interweb and getting worked up over someone elses opinion is certainly a waste of energy. Just do as some do to me, Act like you dont see the post.

Ya can't set the hook on a fish that don't bite ;)

Good Morning Everyone!!
Hey good morning! The blob I was so concerned about yesterday has been ripped to shreds. (There's a lesson in there...) JFl...relax. Stand on your head, maybe; that always gets blood flowing away from the emotions and back to the brain. We're exchanging opinions; don't take it personally.
JP06 is a most trusted and conscientious participant of this blog who has made a lot of friends here, but it's not a clique...Everyone is always willing to talk to anyone! There's a lot of info, exchange of ideas, varying levels of knowledge and no requirement that everyone agree.
morning..anyone notice the blob just below the mex. tex. border..it seems to be heading east..just wondering with the temps. of the water in that area..what would be the chances of development?
practically zero...low or depression could form in the environment, but not a storm.
Anyone else having trouble with the GHCC site? Can not seem to get it to load.
not loading for me either SJ
Thanks SC. If anyone finds out anymore info on it please WUmail me. Hopefully it will be back up and running soon. Not sure what I would do with out the GHCC.
Well yes and no, its not good to get worked up, but I have seen a few really good posters get fed up and leave because of the negativity here. I think by being very clear on expected behavior we can avoid misunderstandings later.

I will not tolerate the excessive disrespect.

If you want to be liked for your expertise and professionalism then by all means show it to everyone. Not just your friends.

I see a good reading is showing up on the 850mb Relative Vorticity in Campeche. However, pressure is rising at the buoy.

BTW there is a new invest in the Indian ocean.

this area of disturbed weather has persisted for a day and a half now, it has held its own unlike the other african waves so far...what do you guys think?
Its Working Now SJ.

They Must have been updating
miamihurricane12 yea,

It actually died down a little as it came over water then strengthened again. So its doing well. I think we should see some symmetry soon in the still pics.
Hey guys,,, i got a ?? last couple weeks i cant get the TSR forecast to come up for me.. It says do I want to save or find a site to open it. it takes me to adobe which I already have installed? any ideas?? I cant even open up PDF files from hurricane center archives either?
911 AM EDT MON JUN 18 2007





this area is the monsoon trough. sometimes there are perturbations from this trough which goes on to develop into something. this one would expect during the july -sept period.
The windward system isnt faring too well now.

stormhank I had some trouble after java updated. I updated my windows computer with the Microsoft updates and everything seems to be working fine.

At the Campeche buoy the winds just picked up and are coming around. Pressure not all that low, but the Buoy is still a ways form the storm. Storms can develop fast in this area (1958 for example). Considering the rain Texas and Mexico have had and the possible northern trajectory I think this one bears watching.

The Tropics are the clearest I EVER seen it...Well, going to work...bye
Good Morning all. Hope everyone had a nice Father's Day. Nothing brewing in the tropics when does it really start up?
Anybody know what they are saying about the blob in the Bay of Campeche?
Theres nothing of real interest in the tropics currently. It has been brought up before that June isn't suppose to be active. A disturbance has to have a LLC to be looked at with great interest. The GFS doesn't show anything forming and there isn't anything out there that could form. Wind shear is around 20-30 knots which wouldn't allow for tropical storm formation.
During the months of June and July, the Bay of Campeche is considered one of the "hot" breeding spots for Atlantic hurricanes.[1] The bay is also considered the eastern border on the main migration routes for birds in the Americas.[2] Wikipedia
I never knew that. I wonder which season the birds migrate.