Eastern Pacific Hurricane Watch -  Hurricane Cosme with an Asterisk

So, without the formation of a tropical cyclone to move the solar energy from our hurricane birthing zone outward from the equator, the water over a very large area is more than 1°C warmer than normal. There hasn't been a shortage of Tropical Waves in the Eastern Pacific hurricane basin. In fact there have been an endless procession of waves across the region, about 36-48hrs apart. So far, none of the waves generated in the deserts of Africa have been utilized in storm formation in the Atlantic. So what is keeping our normal formation of tropical cyclone from dispersing this energy?

Certainly, it must be more than a positive forecast issued by the NHC for a lighter than normal year. There are two weather factors that stand out. High pressure closer to the Baja peninsula than normal and a building of the La Nina cooler waters along the equator west of Ecuador. The graphic right shows the usual movement of the Pacific High as the northern hemisphere warms up in the spring. The High off the Baja coast that gives us our bright clear winter days strengthens and move to the NW. By early July the High has reached full strength usually greater than 1030Mb. It diverts the tropical moisture from cyclones on the western side of the Pacific into Alaska, Canada and as it's influence diminishes over our region, the storm track makes it's way into Baja.

For the last several weeks a ridge has extended from the new High SE to almost the Socorro Islands. This has thankfully kept our humidity low in Baja while keeping our hurricane birthing zone very dry. But those clear blue skies have allowed a lot of the sun's energy to accumulate in the tropical region.

Take a look at the Sea Surface Temp Anomaly graphic left. This shows the above/below temperatures for our Hurricane Basin since the beginning of Hurricane season. Near the first of June we see the temps drop to near normal, after the passage of our first two tropical cyclones. Since that time though we can see the progressive build up of energy as the temperatures have risen to almost 2°C above seasonal normal in our hurricane basin. But one of the things that maybe keeping us storm free can be seen along the bottom edge of the map. Colder than usual equatorial water can be seen inching it's way northward at a time when it should be warming up! Between 100 and 110°W, nearly as far north as 5°N, there is water that is more than 2°C colder than normal. This finger of cold water extends more than 1500 miles westward from the South American coast. Along that colder water can be found a mirroring ridge of High pressure (1012Mb as of 7/17/07) that is keeping the storm track along the ITCZ pinched between it, and our late season High mentioned above. These two bodies of drier air have keep the moisture ready to be stimulated by a passing tropical wave to a minimum.

For those Baja fishermen the news is unspectacular, as most of the waters in both the Pacific and the Sea of Cortez are about normal or a little below for this time of the year.

Looking at the Sea Surface Temperatures we can see how the +29°C and above water has expanded along the southern coast of Mexico. At the time of this article a broad band of thunderstorms exists almost along that entire coast and is about to be stimulated by a tropical wave. Although the NHC does not currently forecast significant development of this system, there is a chance Baja could see some rain late in the week. It is extremely unlike that we would see landfall of a tropical cyclone on the peninsula this early in the season. The earliest landfall of a tropical cyclone (in this case a tropical storm) was August 15th. It is also possible, and perhaps more likely that the afore mentioned late season High will drain the moisture from the system long before reaching Baja Sur.

Looking at the all important 26°C thermo cline, we can see it now encompasses the entire Sea of Cortez and the tip of Cabo San Lucas. Later in the season, the 26°C line will migrate as far north as Turtle Bay on the Pacific coast while temps in the Sea of Cortez will easily clear 30°C. This is when the threat becomes the greatest to Baja.

Now it's time for the fun part... ZAP! I just devastated my average with last three weeks prognostications - I scored a perfect 0%! I called for a tropical storm to form in the first week and our first hurricane of the season to form last week - neither came to pass. The best that the Eastern Pacific Basin could scare up in the last two weeks was TD4E which only existed for about 36hrs. Last week we were moving the Insider Offices and I never finished my guesses for the week ahead and we received Hurricane Cosme., so last week is a wash.

So it's time to redeem my record and look into the crystal ball for the week ahead. I've been saying we are due up for three weeks and been skunked without a storm formation in our basin. This time I'm going to go with another dry week. The High off the coast of Baja I think will remain a factor through the weekend. with all that dry air on both sides of the Hurricane Zone it will be hard for the next tropical wave to find moisture to stimulate into a storm. Speaking of tropical waves, we have one more in the pipeline that should arrive in our basin in the next 24-36hrs. After that there are two more all the way back to the African coast. The eastern most wave is already stimulating a tropical Low which may provide some excitement for the Atlantic Basin this week. The second week, I just don't see how we can avoid having a tropical cyclone before the end of the month. I think a Tropical Storm will move well SW of Baja off into the Pacific.

I had promised to talk about Computer Prediction Models and how they fail along with Deep Water Convection and how it strengthen storms, rapidly... but our continued lack of cyclones took center stage. Next week you can learn why you don't look at any one of the computer models as a source for a projected storm track. Learn how to tell someone who really DOESN"T know hurricanes when they say "Well, one of the models puts it right across Baja!"

Until July 24th ... Clear skies and fair winds!   Tomas

Our Eastern Pacific Hurricane Watch is an editorial 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.