East Pac and Atlantic Basin trying to get ahead of schedule

The east Pacific hurricane season does not officially begin until May 15 and the Atlantic season not until June 1. However, that does not mean that the tropics will wait until those dates to start producing interesting weather.

Many of the global computer models are hinting at tropical cyclone development in the southeast Pacific and possibly in the western Caribbean over the next week to 10 days. Water temps are warm enough, no question about that. But will upper level winds and other factors such as dry air be pro or con for development? Let’s take a look.

May 10-20 Points of Origin Map (graphic 1)

May 10-20 Points of Origin Map (graphic 1)

First, how about climatology. If we look at the points of origin for tropical cyclones from May 10-20 (graphic 1) we see that both basins have almost the same number of developments 9 for the Pacific, 8 for the Atlantic. So it is possible to see development in both regions during this upcoming time period. This also makes me wonder why the east Pacific starts on May 15 and the Atlantic does not. They both seem to have the same chances for development from this date forward. Interesting, but not for me to decide.

Caribbean Sea Vertical Instability Graph

Caribbean Sea Vertical Instability Graph

Next, let’s look at the vertical instability for the Caribbean right now. Granted this is the current pattern, but it will give us an idea of whether or not the mid-levels of the atmosphere are too dry. As we can see, the vertical instability is currently running just a tad above climatological levels, meaning that the air is nice and buoyant or unstable. This is important because a stable, drier environment, like we saw for almost the entire hurricane season last year in this region, will not allow for tropical cyclone formation or at least keep it weak and disorganized. This is a marked change from last season and something we’ll need to monitor throughout the upcoming season.

GFS 168 Hour 200mb Forecast

GFS 168 Hour 200mb Forecast

Next, upper level winds. The GFS forecasts a fairly nice area of high pressure at the 200mb level in a week. I won’t look beyond a week since too many variables come in to play. But right now, the latest operational run of the GFS shows an area of favorable upper level winds developing over the western Caribbean Sea, extending from the southeast Pacific actually. All we need now is a disturbance of lowering of the surface pressures to set off tropical convection. Will that happen? The various models suggest that it might. I would bet more on the east Pacific than the Caribbean right now, but do not discount entirely the chance of a named storm in the east Pacific followed by the chance of one forming in the western Caribbean Sea before June 1. It’s rare, but it does happen and the region we’ll be watching, according to the climo map in graphic 1, shows that we’re looking in the right place.

So for now, just something to monitor and nothing to be concerned about, not in the least. As things develop, or not, I’ll post more info here and via our Twitter and Facebook pages. Not following us there yet? Click either of the two icons above to join the social media side of HurricaneTrack.

 

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HurricaneTrack.com Client Services season pass and “early bird” specials now available

As we approach the 2012 Atlantic hurricane season, we have made available two great plans for our subscription service. One is the season pass which gives you 100% access to all of our Client Services features for just $59.95 from now through November 30. That’s right, only one payment for the entire season. We had several dozen subscribers who really enjoyed this package last year and hope to expand upon that this time around. For those who took advantage of it in 2011, now is a great time to sign up and get started again.

For those wishing to have a smaller monthly subscription, you have until the end of the month to sign up for our $9.95 per month “early bird” special. This too was quite popular with almost a third of our member base last season.

Of course, we still offer our annual plan of $99.95 which is billed only once per year. More than half of our members are on this plan and we appreciate their continued support since the inception of our service back in 2005.

Why sign up at all? It’s simple. Our subscription service is like none other. Members get access to 100% ad-free live video feeds, a daily video update and briefing during the hurricane season, off-season video blogs, live chat with our staff and other members (troll free I might add since EVERYONE is a paying member, no free-loading troublemakers like you see on other public chats), 30 frame satellite and radar loops, large Stormpulse maps, several types of our own Java tracking maps and a member forum. And last year we introduced member streaming where by our members can stream THEIR weather to other members right from their computer and web cam. It is amazing to see our streams sure, but adding in member streams as well was a fantastic idea (one of our members suggested it) and it works so easy. All of these features make up our Client Services site.

So, if you’re interested in going beyond our blog, we have an extensive menu of subscription based services at a fair price. Our clients include folks from the insurance industry, emergency management, media, hospital management, power companies, insurance adjusters, pilots, retirees who own property or otherwise live along the coast, and many other segments of our population who just have an interest in hurricanes. In fact, 9% of our memberships are from people outside of the United States with Great Britain leading the way. We are very proud of what we offer in return for the hard earned money of our private clients. What they get in return is our dedication, innovation and an experience like none other. We spend most of the time talking about what may or may not happen tropics-wise but when the time comes and we have to head out in to the field, our technological advances really shine.

Check out a full description of Client Services here and sign up today! You’ll be part of a growing group of like-minded people who are all very helpful to one another and us too! The interactivity between the members and us is incredible and I wouldn’t trade it for anything.

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Understand the seasonal forecast not for what it says, but for what it does not say

Tomorrow, Dr. Phil Klotzbach and the team from Colorado State University will issue their first quantitative forecast for the 2012 Atlantic hurricane season. As many who are tuned in to this info already know, the CSU team is likely going to forecast a season with less overall activity than we’ve seen in recent years.

I have already seen a few news reports that trickled out during the National Hurricane Conference last week that had headlines mentioning a “quiet” season ahead. I think that the video below sums up the reality of the seasonal hurricane forecast pretty well. Check it out and when the forecast comes out tomorrow and subsequent updates and additional forecasts are made throughout the rest of the season, keep the advice you hear in the video in mind.

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Big time rains for the southern states

HPC 5-Day QPF

HPC 5-Day QPF

Get ready for some rain! If you live in eastern Texas, Arkansas and indeed a good deal of the Deep South, you’re in for some wet weather over the next five days. Take a look at the HPC QPF map. It shows the forecast precip over the next five days and a lot of it! The culprit? A potent upper level storm system now situated over southern Arizona and moving in to New Mexico. It will tap the warmer-than-normal Gulf of Mexico moisture supply and really ignite as we continue to move through the week.

While rainy, nasty weather is usually not a welcome event, in this case, I think people will be pleased to see it because of the drought relief it will bring.

U.S. Drought Monitor Map- Sept. 13, 2011

U.S. Drought Monitor Map- Sept. 13, 2011

The last few years have been exceptionally dry for the southern Plains and especially Texas. Looking at the U.S. Drought Monitor maps we can see that at the peak of last year’s hurricane season (Sept. 13 map), nearly the entire state of Texas was experiencing exceptional drought conditions. I have little doubt that this was the reason why TS Don literally dried up as it made landfall in south Texas in July. In fact, the air mass over the western Gulf remained very dry for a bulk of the hurricane season. When TS Lee formed in early September, it too entrained the bone-dry air over the region and actually transformed in to a sub-tropical storm, losing its purely tropical characteristics. I call this phenomenon the Texas Air Layer, similar to the Saharan Air Layer which can dominate the tropical Atlantic with dry, stable air.

Now let’s fast forward to the current winter pattern. We have seen quite an increase in rain fall over a significant portion of Texas and surrounding states due to a favorable storm track and possibly a warmer than normal Gulf of Mexico which supplies more moisture for storm systems. It has also been warmer than normal for the region as it has been for much of the Southeast. This is partly due to a positive NAO or North Atlantic Oscillation which has kept the deep east coast troughs which usher in Arctic Air at bay. Instead of prolonged periods of cold, dry air, the Arctic attacks are brief and the result has been a warmer, wetter winter for much of the southern tier states.

U.S. Drought Monitor Map- Jan. 17, 2012

U.S. Drought Monitor Map- Jan. 17, 2012

You can see the resulting improvements on the latest Drought Monitor map labeled January 17. A remarkable change to say the least and more rain is coming which will further knock down the dry conditions for Texas and elsewhere.

My theory is that if this pattern continues, perhaps the air mass over the southern U.S. and adjacent Gulf Waters won’t be as dry this hurricane season. If this is the case, maybe, just maybe it would open up the western Gulf, Texas included, to more tropical cyclone activity. It makes sense to some extent: if the abnormally dry air mass is gone, due in part to a wetter land mass underneath, then it stands to reason that approaching tropical cyclones won’t dry out nearly as much as we saw in 2011. I think we can all agree that watching Don erode away to nothing as it made landfall was one of most incredible demises to a tropical storm that we’ve ever witnessed. It provided next to no rain fall for the region that it impacted and was all but gone in less than 24 hours after landfall.

We’ll see how this all plays out for the upcoming hurricane season. It may have no bearing at all but I think that drought begets drought and thus more dry air; a kind of feedback mechanism. We know that tropical cyclones are incredibly sensitive to dry air and what we saw over the western Gulf last season was enough to keep the region well protected. I’ll keep tabs on the Drought Index and post a follow up report in the early part of June. For now, enjoy the abundance of rain fall but be mindful of the hazards that excessive rains can bring. It’s all good until somebody gets hurt and we don’t want that.

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How’s that La Niña going?

Subsurface Temps of the Tropical Pacific

Subsurface Temps of the Tropical Pacific

So far this winter, the La Niña that has been in place since last fall continues to hold strong. As the graphic from the Bureau of Meteorology in Australia indicates, subsurface temperatures across the tropical Pacific remain much colder than average over a large area. There is a growing region of subsurface warmth beginning to pool in the western Pacific but it lacks a real mechanism to drive it eastward- a so-called westerly wind burst. We typically don’t see those unless there is a significant pressure change across the Pacific and that shows up in the SOI or Southern Oscillation Index. When it is substantially negative, and persistently so, the trade winds often slow or even reverse, allowing the warm water gathering in the western Pacific to migrate eastward.

The latest update from the BOM also points out that long range climate models suggest a gradual warming of the tropical Pacific as the La Niña fades. This means it is likely that we’ll see a return to more average, or neutral ENSO conditions (ENSO stands for El Niño Southern Oscillation) by the time summer arrives in the Northern Hemisphere. There is also the possibility that the warming will continue and a weak El Niño could set in by next fall. I do not see any evidence yet to suggest that a strong El Niño is coming. However, this time of year, it is difficult to predict what will happen several months down the road but the large subsurface cold pool coupled with a fairly strong SOI signal over the past 30 to 90 days tells me that La Niña is going to be the rule for a few more months at least.

Why does any of this matter? Aside from the effects outside of the hurricane season, which are far too detailed to get in to in this post, we typically see a more active hurricane season when El Niño is not present. This is due to the stronger and more numerous instances of wind shear, the change of wind speed and/or direction with height, over the deep tropics. El Niño events promote this negative impact to tropical cyclones where as La Niña events usually do not.

For now, the La Niña pattern will continue but we’ll watch for signs that it is breaking down and then we’ll see how much warming takes place in the tropical Pacific. The end result could have an impact, one way or another, on the upcoming Atlantic hurricane season. I’ll post more about the ENSO state next month.

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