Eastern Pacific Hurricane Watch - Cleaned Out by Dora
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Updated July 27, 2011 Wow, Hurricane Dora was quite a storm, but the climatic factors just aren't quite lined up for a true threat to the Baja peninsula... yet.
This is the seventh year of the Hurricane Watch Reports. In no small part, tropical cyclones and their affect on Baja have been a big part of the summer attraction to our website over the years. In 2003 Hurricane Ignacio and Hurricane Marty brought out first huge surge of traffic to the month old BajaInsider, as we were about the only web source for information on these storms and US media hadn't discovered Baja yet..
Fascinated by these powerful creations of Mother Nature I began my education in the physics and mystery of these powerful storms.
Today you can find many sources for hurricane information on the web, but to my knowledge we are the only English reporting source that is actually HERE in Baja California Sur. Our Weather Department now provides many unique graphics to help you understand the forecasts and make your own decisions on storm preparation. We also endeavor not to get caught up in the press headline hype game, we take it seriously but try to tell it like it is.
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Why not Dora?
For those that have been through the Hurricane Season here in Baja it was easy to tell that we just aren't into our threat period yet. During the approach Hurricane Dora our humidity rose a bit but nowhere near what it will be in a few weeks. The overnight low in La Paz last Friday as Dora approached was 73°F, again, just not ''hurricane weather".
Believe it or not, hurricanes are delicate creatures, they require just the right mixture of environmental conditions to survive. Shear winds, humidity, water temperature and more must be just right for the hurricane to form and survive.
Over the past 8 years I have followed each storm closely and the predictions from the National Hurricane Center. Their computer models have been refined and if you look at the animation right of the storm track of Dora you can see how accurate the forecasts have become. However, their intensity forecasts leave a little more to be desired.
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With Hurricane John in 2006 the National Hurricane Center warned us of the approaching storm and the potential for landfall of a Major Hurricane. (Major Hurricanes are of category 3 or greater) Along the southern coast of Mexico John achieved Category 4 status, dipped back to Category 2, then just a few hundred miles south of Baja gathered enough intensity to become a Category 3 again. The forecasts grew dire and major media jumped all over it.
As it was, John was reduced to a Category 2 storm well before reaching Baja. Why?
When we look at the path of 2006's Hurricane John in the graphic left it helps to explain why we almost never get a Major Hurricane in Baja. The waters along the southern coast of Mexico are where most of our storms are spawned are above 29°C and away from the continental shelf the waters are deep too. This area provides a plethora of energy to build storms. The waters around Baja California Sur rarely get warm enough, deep enough to provide the energy for a Major Hurricane landfall on the peninsula.
As the tropical cyclones move north the waters cool and depth to which the warm waters goes grow increasingly shallow. The ebb and flow of the Sea of Cortez churns these waters and the warm water is only closer to the surface. Just as the storms approach the Baja Sur coastline, it really shallows up.
All these factors add up to the fact that in 55 years Baja California Sur has been hit by two Category 3 Major Hurricanes, Paul in 1982 and Kiko in 1989 both made landfall on East Cape. Hurricane Liza in 1976 roared past East Cape to the east and was a Category 4 storm. Flooding caused thousands of deaths when a dike burst south of La Paz.
So, with there being approximately 800 hurricanes in the Eastern Pacific since 1954, a landfall of a Major Hurricane in Baja is 'almost never'.
This of course does not discount the chance of a Major, never say never to Mother Nature. It also does not down play the dangers of a lesser storm, Hurricane John battered East Cape, downing trees and power lines and ripping roofs away. If we do ever receive a forecast for a Major storm, please pay attention. Major Hurricanes are called that for a reason and are an entirely different game from our usual Category 1's and rare Category 2's.
When we look at the Sea Surface Temperature graphic right it is evident how much energy Dora removed from the Pacific. The warm +29°C waters along the southern coast of Mexico had all but disappeared. The all important 26°C thermo cline has wrapped around the tip of the peninsula into the Pacific from the Sea. Waters below 26°C can't support cyclonic development and storms lose integrity very quickly when over these cooler waters. Between the air temperatures and the dry air, Dora never really had much of a chance to make a Baja landfall as a serious storm. Unfortunately, we didn't even get much rain from the event. Most of the precipitation in Baja Sur last weekend was from moisture moving west from the mainland, not from Dora.
So why didn't Dora pose a greater threat to Baja? I guess it is simple, it is just too darn early in the season.
Dora reduced the temperature in the Eastern Pacific significantly. At her peak Dora was releasing energy equivalent to a 20 megaton nuclear weapon every 12 minutes. Dora fell one knot of wind velocity short of being a Category 5 Hurricane. Dora was the sixth most powerful storm in the Eastern Pacific in the last 35 years. The photograph at the top of the page shows Category 4 Hurricane Dora in her full glory, just shy of Category 5 intensity.
When looking at the SST anomaly graphic left the areas southeast of Baja, where our hurricanes are born, was creeping up to above normal temperatures last week and Dora made good use of it. Now there are areas in the same region that are below normal. The Sea of Cortez still remains slightly above normal.
Looking at the week ahead...
Now that the threat to us here in Baja becomes more real, our Hurricane Watch Reports will be issued weekly through mid October when our season draws to a close. Dora swept the Eastern Pacific basin clean and dispersed a lot of tropical energy northward.
When we look at the wide angle surface chart below we see the formation of a potential storm, stimulated by a tropical wave (red arrow) in the Gulf of Mexico. It is likely that this storm will use up the energy from this wave and it won't make it to our basin. The next tropical wave is just entering the Caribbean (yellow arrow) and there is a trough ahead of that wave that could spawn another storm in the Atlantic basin. If it doesn't, we may have to keep an eye out late in the week as it enters the Pacific. The next tropical wave is about 7 days away from us, just off the coast of Africa. That wave already has a Low attached to it and may form a third tropical cyclone in the Atlantic well before reaching us. Hurricane don't require a tropical wave, but they are considered the seeds of tropical cyclones.
Following the passage of Dora the Inter Tropical Convergence Zone, the Tropical Wave pipeline, shifted south again. Much of the ITCZ is very close to the 10°N latitude. Cyclones need the Coriolis Affect (that which makes whirlpools go the same way in this hemisphere) to make them spin as the warm air rises. Cyclones rarely form below 10°N (or south) latitude. and although I never say never one of my resources says never below 8°away from the equator. Good news for us, as when the ITCZ swings up along the coast of southern Mexico in about 30 days is when we really need to pay attention.
More below...
My Prognostications...
Now for the fun part. I get a 100% for the last prognostication of my Ouija board and crystal ball combo. I said that Dora would be too weak by the time it reached our vicinity to provide more than a little rain. Dora in fact nearly vanished about 190 miles SW of Cabo San Lucas and only provided some big surf to the south facing beaches. When I roll the bones, cast the dice and read the Ouija board it is almost too easy to predict the week ahead. Dora cleaned things out - we will have a quiet week in the Eastern Pacific I think. That third tropical wave is the one to watch. The Eastern Pacific will have time to accumulate some moisture, build some decent thunderstorms along the southern coast of Mexico and provide fertile 'ground' in the ocean if you will, for the formation of our next tropical cyclone. Still, the flow of the Eastern Pacific wind currents and the depressed ITCZ should take the next storm to the southwest of Baja.
See you next week!