Eastern Pacific Hurricane Watch - The Baja Hurricane Season Begins!
Update August 16, 2010 August 15th is really the beginning of the Baja Hurricane Season. The all important 26°C thermo cline (see Sea Surface Temperature graphic below) now encompasses the tip of the peninsula, making landfall of a tropical cyclone in the region possible. As of the writing of this article we have a Low pressure system 350 miles south of Cabo San Lucas. This system is not currently anticipated to develop further, as it will move over cooler waters.
Normally by this point in the season we have about 6 named storms by now, this year just 5 named systems have been generated. Usually 2 of those are hurricanes and one would be a Major Hurricane, of Category 3 or greater. Well, we've had our two hurricanes, but both of them have been Majors, a Category 3 (Darby) and a Category 5 (Celia). So, perhaps we are even a little ahead of normal considering the force of the storms.
We are now very close to what we call the Baja Hurricane Season. Although the Eastern Pacific hurricane season begins May 15, Baja California Sur is rarely threaten by tropical cyclones before the end of August. The earliest recorded hurricane to make landfall in Baja was an unnamed storm on 1954. This allegedly Category 1 Hurricane moved along the western side of Baja California Sur and made landfall near San Ignacio on July 16, 1954. Now, we say allegedly because there were no satellites, Hurricane Hunter Aircraft and only one weather station on Baja Sur, at the tiny La Paz airport at the time. This hurricane originated in the Gulf of Tehuantepec. Personally, I doubt the claim, as in mid July the waters on the Pacific side of Baja are no where near the required 26°C to sustain a tropical cyclone. (see graphic below) We don't have Sea Surface Temperature date from 1954, but 2010 is very close to the 20 year norm. Since tropical cyclones usually spin apart in less than a day over cooler waters, I find it hard to believe that this system maintained hurricane strength for 3 days as it traveled over down right cold water to San Ignacio. But never bet against Mother Nature, unlikely as it seems...
In "modern" history Tropical Storm Calvin made landfall at Los Barriles on July 8th, 1993 and Tropical Depression Genevieve (once TS Genevieve) made landfall in the Comondu region on July 16, 1984. Tropical Storm Calvin approached Baja from the only plausible direction for a tropical cyclone to maintain intensity over +26°C water, along the coast of mainland Mexico. On the graphic right the important 26°C thermo cline is outlined in red. It is easy to see how Calvin could remain over warm water while Genevieve would have been weakened by the colder waters of the Pacific.
Now in August the 15th of the month seems to be a magical number. Despite the 'chance' that exists from mid July on, no other tropical cyclone has made landfall before the 15th. Perhaps it is a union thing.
Hurricane Doreen on August 15, 1977 is my bet for the earliest hurricane to make landfall in Baja. This Category 1 Hurricane again moved along the Pacific coast of Baja California Sur and made landfall near Magdalena Bay and again as a Tropical Storm near San Ignacio.
In the third week of August two hurricanes Emily and Diana, along with three tropical storms, another Emily, and Hyacinth made close passes to Baja, but none made landfall.
The final week of August is a bad one for landfalls of tropical cyclones. Tropical Storm Julio was next, making landfall on August 24, 2008. Julio moved across the peninsula and dumped rain on the Loreto/Mulege region for several days and caused major flooding for just being a tropical storm. Hurricane Ignacio, moved along the east side of the peninsula on the 23rd to 25th of 2003 and was my first Baja Hurricane.
Kiko, the only Category 3 Hurricane to ever make landfall in Baja did so on in the East Cape region of Baja Sur on August 27, 1989. Kiko was a freak storm that blew up from a Tropical Depression off the Tres Maria's Islands and crashed ashore less than 32hrs later as a Category 3 Hurricane in less than 200 miles. With little warning it is fortunate that the East Cape was not as populated as it is today.
On this note, we will begin weekly updates to our Hurricane Watch Report and continue to do so through mid October, when our statistical probability of tropical cyclones falls off just as rapidly as it built up.
Looking at Eastern Pacific Tropical Cyclones in the week ahead...
The Eastern Pacific,as we stated above, has been quiet for 3 weeks preceding Estelle, but we are only one named system behind the 20 year average. We have had fewer than normal tropical waves being emanated from the deserts of Africa, and several of them have dissipated as they travel across the Pan-American Isthmus. Looking at the wide angle surface chart below we can see three tropical waves headed our direction (orange arrow) and the system we are currently monitoring along the southern coast of Mexico. (magenta arrow) The Inter Tropical Convergence Zone (ITCZ) is twisted up along the southern coast of Mexico, through the region that traditionally spawns the tropical cyclones that affect Baja. The humidity and afternoon thunderstorms have just begun in the past few days, so the factors are beginning to line up on us. That's the bad news.
The good news is the oceans are about normal in temperature. Over the last 5 years the Eastern Pacific Hurricane Basin has been as much as 3°C above normal. Additionally, upper level winds continue to blow to the WSW from the mainland to south of Cabo San Lucas. It isn't the end all, but this can drive storms west, rather than up into the Sea of Cortez.
More below...
Sea Surface temperatures give us a strategic look at where storms might form. When taking a look at this weeks Eastern Pacific Sea Surface Temperatures we see progressive seasonal warming of the Eastern Pacific, but nothing particularly abnormal. Tropical cyclones need sea surface temperature water of more than 26°C. That all important thermo cline now wraps around the tip of the peninsula and all of the Sea of Cortez is warmer than 28°C, some parts along the eastern edge are over 29°C
The waters along the southern coast of Mexico, from which most of the storms that reach Baja are generated, is between 29° and 30°C, perfectly capable of generating a tropical cyclone. The animated graphic left shows the progressive warming of the Eastern Pacific. Although the sun has passed the solstice almost two months ago waters between the equator and the Tropic of Cancer (which crosses the tip of our peninsula just north of Cabo San Lucas) will continue to warm for another couple of weeks.
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Live Storm Tracking Satellite View |
Looking at today's satellite image we can see the system 325 miles south of Cabo San Lucas. Upper level winds still plague that area within the day the system will move over waters that are cooler, although capable of supporting cyclonic action are not as likely to generate a new storm. The system is forecast to move to the WNW without becoming a tropical cyclone and may deliver a little spin-off rain to the SW corner of the peninsula over the next two to three days.
The Sea Surface Anomaly graphic left continues the good news for Baja. Most all of the Eastern Pacific basin is at or only slightly above normal sea temps for this time of year. From the perspective of the energy contained within the ocean's surface, it means we should be having a normal year, which plays out in this seasons normal numbers
Good news for tropical cyclones and bad news for fishing off the Pacific coast of Baja Sur is a large area of water that is as much as 2°C to 3°C below normal. Extending about 500 miles south and 600 miles west this cooler than normal water contains less kinetic energy than normal. If this holds through the rest of the season it could mean storms that curve back toward Baja would have less warm water from which to gather energy before making landfall.
The Sea of Cortez is also just above normal for this time of year. Folks here in Baja Sur are delighting in the continued evening winds and cool nighttime temperatures that we have enjoyed. Our evening winds usually quit about the middle of July, but with the difference between the land's daytime solar heating and the temperatures of the Sea, the winds are a welcome relief. Fisherman have complained that the water is colder than normal, and hence the fishing a bit slower. This would be true of just looking at the last 5 years, where the Sea has consistently be 2°-3° above the 20 norm.
So now for the fun part...
In every Eastern Pacific Hurricane Watch Report I take my best shot at a strategic look at now just the week ahead.
Last week it looked almost certain that the system SW of Acapulco would spin up into a tropical cyclone. Even the NHC gave it 80% probability. Well, the system moved over land, and that was the end of that. The system south of Cabo is not likely to spin up. Tropical waves are dissipating very quickly when entering our basin, but at least three are on the way in the coming week. With the waters between Baja and Puerto Vallarta just above normal now, I think we'll have a tropical storm move closer to Baja in the coming week.
But what do I know...
Tomas Zyber
Our Eastern Pacific Hurricane Watch is an editorial/entertainment analysis of data from the National Hurricane Center, NASA and NOAA and is based on information provided by the same, but is an amateur endeavor. For actual storm information readers should refer to notices and warnings posted by the National Hurricane Center. or visit the Mexican Nation Metrological website for more information.
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