Last advisory issued on Tropical Depression #1

Sorry for the lack of updates over the past couple of days.

Tropical Depression #1 never did organize enough to be upgraded to Tropical Storm Ana (the first time since 2000 that the season's first depression didn't become a named storm), and after racing northeast, not affecting any land areas, it has lost it's tropical characteristics and the National Hurricane Center will no longer track this system.

Tropical Depression #1 and Invest 90L have proved to be interesting storms to track and the off-season is now finished, even if it's still a few days to go until June 1st.

There's nothing else of interest right now in the Atlantic or East Pacific basins but we'll keep a close watch on the tropics.

Any comments will be appreciated.

Pre-season Tropical Depression #1 forms off the East Coast

Very quick update. Invest 91L has formed into Tropical Depression #1 east of the Carolinas over the western Atlantic. Maximum sustained winds are 35mph. It is expected to become Tropical Storm Ana later today before moving northeast and dissipating. It is not expected to impact land in any way.

More later.

Invest 91L off the Outer Banks. Will it develop? Please Comment!

Invest 91L is now centered about 120 miles south of Cape Hatteras, North Carolina and is moving north at 10-15mph. It should move more to the northeast tomorrow, but it's projected path means coastal North Carolina may still receive some bad weather with showers later today.

91L has a nice circulation but lacks much convection near or over the center, and it does need to cope with progressively colder waters (too cold to support tropical/subtropical development by tomorrow afternoon) and moderate wind shear. Still, it does have a chance of forming into something (although it will have to organize significantly within 24 hours to do so), probably subtropical rather than tropical, and probably a depression (winds less than 35 knots) rather than a storm (winds greater than 35 knots). I'm giving it a 20% chance of becoming a subtropical depression within the next 24 hours. One thing to mention is that the National Hurricane Center has finally issued a special tropical weather outlook for this system, and will issue another one at 1PM, and they are sending recon to check it out.

The fact that we've had two areas of interest (90L and 91L), one of which very nearly became the first named storm of the season (Ana), in the Atlantic so far (and Atlantic hurricane season is still yet to officially start) may be of some significance. However, whether this is a sign of things to come or not is up for debate.

The GFS forecast model is predicting a closed surface low forming in the Gulf of Mexico in a few days from now, and moving over Florida bringing yet more rain to the already drenched state. However, it has been noted that GFS is having some problems so this is likely a false alarm, and it's even more likely that this won't have a chance of becoming anything tropical. To check out the latest model runs (including GFS), click here.

By the way, if explosivedeepening.com is down in the near future, then try explosivedeepening.net, a mirror site.

You are more than welcome to click the Comments link to post comments, news items etc. All comments are moderated before being put up on the Blog.

Invest 91L update

Not too much has changed with Invest 91L, the disturbance south of North Carolina over the western Atlantic. Convection is pretty shallow right now, however there's a few factors, including the warm waters of the Gulf Stream in 91L's projected path, which could favor development into a subtropical or even tropical cyclone, although the latter especially is unlikely. Waters are just too cold in the area to be very favorable for formation; if it was July then this would be of real concern.

Low level convergence is improving, so what we need to watch is for more and deeper convection to develop near the center. There are some indications this will happen, but as of now it's less likely this will become much of anything. (Pressure has been rising since earlier today). 91L has only about 24 hours before it accelerates to the north-northeast and thus has no chances of developing.

As for what impacts this system will have on the Carolinas, the simple answer is probably not much. Any bad weather there will more likely be coming from the pressure gradient between this disturbance and the surrounding area and a frontal system, not from 91L itself. The Outer Banks can expect high surf, some wind (possibly approaching 30mph), and rain, mostly in the form of showers, not heavy thunderstorms.

Regardless of whether we see a tropical/subtropical depression/storm, the fact that we have seen two disturbances designated as an area of interest by the National Hurricane Center in the Atlantic so far this year is quite significant.

By the way, if you find explosivedeepening.com down in the near future, you can go to explosivedeepening.net, a mirror site.

Any comments are more than welcome.

Disturbance off the East Coast, disaster in India and Bangladesh, and upcoming mirror site

This is becoming quite an active month of May!



Another disturbance has formed off the U.S. East Coast and has been designated Invest 91L. 91L is currently near North Carolina and indeed may impact there later on. It looks fairly well organized with a mid-level rotation but not much activity down at the surface (which is required for tropical/subtropical development) that I can see, although there are some indications a surface low may be forming. It is over cool waters, probably too cold for it to become a purely tropical system although slow development into a subtropical depression or storm over the next few days is possible as it moves into warmer waters over the Gulf Stream. Also a thing to note is the majority of it's convection is to the north and northwest of the center, and thus over warmer waters. As of now I'm giving it a 20% chance of developing.

The National Hurricane Center doesn't seem impressed with this disturbance - no special tropical weather outlook has been issued so far.

ExplosiveDeepening does not track tropical systems outside of the Atlantic and East Pacific basins, but I thought I should mention that there has been at least 120 people killed in India and Bangladesh from Cyclone Aila. Aila made landfall as a weak Category 1 or strong tropical storm yet mostly due to the poor preparations and overpopulation in those countries there were still many casualties and even more people injured or made homeless.

By the way, if you find explosivedeepening.com down in the near future, you can go to explosivedeepening.net, a mirror site.

Any comments are more than welcome.

All is quiet for now

The large extratropical cyclone and assoiciated surface low we were tracking was once again designated Invest 90L, and yesterday moved ashore near the Mississippi/Alabama border. However, before landfall it did improve considerably, with squalls near it's center and strong winds. Indeed it is possible it became an unnamed tropical or subtropical storm before it made landfall. Regardless, it did bring heavy rains to Florida and strong winds to the northern Gulf Coast.

There has also been a disturbance in the east Pacific, but the National Hurricane Center no longer believes it has a chance of developing, so for now at least, the tropics are quiet.

Atlantic Hurricane Season will officially begin on June 1 and end on November 30. Pacific Hurricane Season began on May 15 and will end on November 30.

Any comments are more than welcome.

Low pressure area in the Gulf; will it develop? (Please Comment)

Invest 90L is long gone and a non-issue, but we continue to closely watch a low pressure area now over the east-central Gulf of Mexico which is showing some signs of organization. It looked unimpressive yesterday but convection is now developing well east of the exposed low-level circulation center. This disturbance has been drenching Florida lately, with up to 23" of rain being dumped in some areas over the last four days.

The Gulf low needs to overcome some problems if it is to acquire tropical characteristics. Wind shear in the area is a moderate 20 knots, which is enough to allow further development although it is certainly not the best conditions for intensification, but what will likely inhibit strengthening more is the large amounts of dry, cool air in the region. Still, with SSTs (sea surface temperatures) fairly high and wind shear forecasted to decrease over the next few days, it is very possible this system will become a tropical or subtropical depression. (I'm giving it a 50% chance).

Landfall on Louisiana or Texas over the weekend is likely, regardless of formation into a tropical/subtropical cyclone.

Any comments are more than welcome.

Watching tropical disturbances near Florida (PLEASE COMMENT!)

East Pacific Hurricane Season has already begun; it started on Friday and will continue until November 30. However, although the start of Atlantic Hurricane Season is still several days away, we are already watching two systems, both near Florida, which have the potential to develop into a tropical or subtropical depression. One is over the Florida Keys, and the other is over the south-central Bahamas, east of Florida.

The second was designated Invest 90L (i.e., an area of investigation) yesterday and was given a 30% chance of developing, however today it is less organized and the National Hurricane Center no longer believes it will form into anything. Right now it would seem 90L will be absorbed by the other system over the Florida Keys, which is slowly organizing and may be designated Invest 91L fairly shortly, and perhaps eventually become a tropical cyclone once it's moved westwards over the Gulf of Mexico. Wind shear is strong over both lows, however two computer models predict wind shear will lessen over the northern Gulf allowing the Florida Keys disturbance to develop further. I give it a 30% chance of becoming a rare pre-season tropical or subtropical depression.

Regardless of formation, the Florida Keys low may impact Texas over the weekend, which is why we will want to watch it's progress closely.

Any comments are more than welcome.

Hurricane Season Approaching (Please Comment!)

We are getting ready for the next hurricane season which is rapidly approaching. We only track systems in the Atlantic Ocean, Caribbean Sea, Gulf of Mexico or Pacific Ocean east of the International Date Line, as only in these areas does a tropical system pose a threat to Texas.

East Pacific Hurricane Season starts on May 15, and Atlantic Hurricane Season starts on June 1. I'm expecting an early start to what I expect to be an active Atlantic season, with around 14 named storms, 8 hurricanes and 4 major (Category 3+) hurricanes, although right now I'm not expecting a season quite as bad as the 2008 season, which featured the costliest hurricane in Texas history (Ike). 2008 was quite unusual as many systems hit Texas or nearby.

Right now we don't have an El Nino or a La Nina; conditions are neutral right now. (El Nino is a warming of Pacific waters which results in less activity in the Atlantic, La Nina is a cooling of Pacific waters resulting in a more active season.) However, this doesn't mean this season won't be active. Far from it. In fact, 2008 was neutral and 2004 was mostly neutral with a brief, weak El Nino during August, yet both of these seasons featured many intense, devastating hurricanes. And, of course, even if 2009 proves to be overall an inactive season that doesn't mean it won't be long remembered as featuring a single major storm which happened to hit a populated area and caused massive damage. Hurricane Andrew, for example, existed in an otherwise very quiet Atlantic hurricane season.

Typically, hurricanes and tropical storms in the East Pacific don't affect Texas and instead head out to sea. However, it isn't that uncommon for remnants of Pacific storms to move over Texas, and these systems can drop a lot of rain and sometimes can cause some slight damage.

And if you reading this, PLEASE COMMENT!