2011 Eastern Pacific Hurricane Outlook
The Eastern Pacific is one of the most active hurricane basins in the world; it is also one of the smallest. Fortunately, most of the tropical cyclones move west, out into the Pacific. But some threaten Mexico and Baja California Sur. We take a statistical look at the Eastern Pacific Hurricane Outlook for 2011.
Here we are at the beginning of the 2011 Eastern Pacific Hurricane Season. Everyone always asks at this early stage what is in the long range forecast for Baja. Honestly, even the professional forecasts, with tons of global data have made some pretty significant ‘bad guesses’ in the last few years, particularly in the Atlantic.
To read the latest Eastern Pacific Hurricane Watch Report click here.
Last year, 2010, was a particularly ‘light’ year in the Eastern Pacific. There were only 3 hurricanes, Celia, Darby and Frank which were two majors and a Category 1 respectively. There were only 7 named storms in 2010, usually we start to pay attention around the 8th storm of each season, when we get past the “G’s”.
We in fact DID have landfall of Tropical Storm Georgette, the last named storm of the season, but here in La Paz we received less than ½” of rain, although the Cabo area got a little more. Georgette was a dud.
Hurricanes are important to Baja
Last year left Baja California Sur with a significant rainfall shortage. The rainy season for Baja Sur is in the hurricane threat period from the end of August to early October. The annual rainfall in this region is about 7.5” per year. The mountain regions usually get significantly more rainfall, with nearly daily thunderstorms.
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That just plain didn’t happen in 2010. Although other parts of Mexico were inundated with too much rain, in fact the wettest in Mexico’s weather history, Baja Sur had one of the driest years in history. A decent tropical cyclone can easily dump our entirely yearly rainfall in a matter of hours. A few years back the Mulege area received up to 27” of rainfall in a three day period from a stalled tropical depression and caused severe flooding.
The norm is 16 named storms (Tropical Storm strength or better) 9 hurricanes and 4 of them major hurricanes. A major hurricane is Category 3 or greater. Major hurricanes are a different animal than what we usually see here in Baja. In the last 50 years only one Major Hurricane has made landfall in Baja, and that was Hurricane Kiko which developed very quickly off the Tres Marias Islands and made landfall 24hrs later on East Cape in 1989.
For more Historic Hurricane Information click here.
When is Hurricane Season?
The Eastern Pacific Hurricane Season is 16 days longer than that of the Atlantic. The Eastern Pacific season begins on May 15 and the Atlantic’s begins on June 1. Both Seasons end on November 30.
The Baja Hurricane Season is much shorter. Sometimes in late July we get a rogue storm which will pass close enough to the tip of the peninsula to provide some rain and some outrageous surf. But the earliest landfall of a Tropical Storm or Hurricane on the Baja peninsula is in mid August. The last decade has made the last week of August and the first few days of September the peak of our threat with 5 named storms making landfall during that 10 day period. Over the last 50 years the curve peaks in the third week of September. The threat remains high through the second week of October. Then as clearly as the threat began in mid August, the threat drops to zero by the third week of August. The latest tropical cyclone to make landfall in the last 56 years was on October 17.
What’s up for 2011?
The ENSO or El Niño/La Niña-Southern Oscillation is retreating toward a ‘normal’ or non-year. The waters of the Nino effect are well south of the area where the Eastern Pacific hurricanes form, but the affect on the weather patterns is that to generally reduce the number of storms in the Eastern Pacific. Colder ‘Nina’ years have fewer storms than warmer Nino years. Extreme Nino years have also reduced the number of storms as they increase the high altitude winds.
The National Hurricane Center in Miami, Florida has crunched the massive amounts of world climatic data that they have to provide the following prediction for the entire Eastern Pacific: The NHC says that there is a 70% chance of this year being a ‘lighter than normal year’. How much ‘lighter’ provides lower confidence in the predictions as they call for 9-15 
Named Storms, 5-8 Hurricanes and 1-3 Major Hurricanes. Basically that covers a pretty broad spectrum and is just one storm lower than normal. They do not makwe any predictions as to landfalls.
What is good for the Pacific ain’t good for Baja
This is of course good news for the basin as whole but ‘non’ years are not necessarily the best news for Baja. The old ‘rule of thumb’ was that Baja gets a landfall every other year. If we follow that rule we might get this year off. But in the last 10 years we have had at least one tropical cyclone make landfall in 9 of those years.
We have had three seasons with two landfalls in the same time period. This flies in the face of the Eastern Pacific trend when has averaged below normal in tropical storm activity since 1995.
Baja Hurricanes and El Nino/La Nina and Non-years
Last year I revised my data and looked at the ENSO during the hurricane season rather than what had been deemed a Nino/Nina year in January. This affected the statistical results dramatically.
In the last 52 seasons there have been 18 El Niño Years. It is popular belief that the Eastern Pacific Basin has fewer hurricanes during El Niño events. The good news is this is true. An average of 14.47 named systems has formed in El Niño events, a little more than half a storm fewer. But the range is broad, El Niño years have seen as few as 8 and as many as 18 named storms since 1959. The bad news is that in those 17 El Niño years we have had 15 landfalls in Baja of a Tropical Storm or greater. That’s 88% probability of a landfall during El Niño events.
Looking at the years where an El Niño tapered off to a Non-event there were 6 years since 1959 where that has occurred with 6 Baja landfalls during those events. There were an astounding 115 hurricanes that formed in the ‘fall off events’ for an average of 18.5 named storms during those years. 2010 could well fall into this category.
The safest seasons for Baja occur during La Nina events. Again, we looked at the state of the event during the hurricane season. There were 13 La Nina events since 1959 and only 185 named systems formed during those years. That’s an average of 14.23 named systems per season, just a few points better than an El Niño event. Again, the range is very broad; as few as 9 storms and as many as 22 storms have formed during La Nina years. The big difference is only 7 of those named storms made landfall in Baja for a minimal 46% probability.
The worst seasons for Eastern Pacific named storm formation are ‘Non-events’, where the equatorial waters are about normal. There have been 21 Non-event years since 1959 and 347 named systems formed in those years. That’s an average of 16.52 or a storm and a half over normal and 2 storms over La Nina years. In those 21 years there have been 21 named systems to make landfall in Baja, which is a 100% probability.
It looks like 2011 is going to be a ‘non’ year, so hold onto your hats.
There are of course a great number of other factors which affect our hurricane susceptibility. This year they have again forecast it to be one of the hottest in Baja history. Don’t expect to feel the difference as last year set records but the average was less than a whole degree above the norm.
This year has provided some unusual weather patterns already. In most years by the middle of May the weather in the States has little impact on our peninsula. This year we had a North American cold front that dropped temps well below normal just last weekend. The Pacific High has apparently established itself and a ridge of high pressure extends SE to below Cabo San Lucas. This pattern protects Baja from the early season storms (along with water too cool to support cyclonic activity)
Ocean temperatures play a major role in our storm threat. Right now the Eastern Pacific basis in just about normal for this time of year with the exception of the waters between Cabo and the entire southern coast of the mainland. Looking at the Sea Surface Temperature Anomaly graphic we see green or normal temps and the ‘hot spot’ which is 2°C or about 4°F above normal. This would concern me more if this were August, but these temps vary throughout the season and it is just plain too early to worry.
While looking at the graphic notice the large area of above normal waters in the Central Pacific. This caused California’s wet winter and environmental scientists directly attribute this to China’s industrial boom.
My Predictions for 2011 and the week ahead
This is the fun part, every issue of the Hurricane Watch I look head at the strategic possibility of a tropical cyclone. At the beginning of the season I make my predictions for our year as well. I give last year’s prediction a barely passing grade. I predicted more storms and we had significantly fewer storms as a whole in the Eastern Pacific. I did predict the only landfall we would have would be in the third week of September. I thought it would be a Category 2 storm, Georgette turned out to be a dud of a tropical storm in exactly that week. With the season being short of storms and my statistics pointing to a busy year my weekly batting average was very low too, I kept thinking ‘this week a storm MUST form’ but it rarely did.
So gazing into the crystal ball and scanning the Ouija board for 2011 I think this year will be about normal for the Eastern Pacific as a whole. But with no more than a gut feeling I’m going to say two tropical cyclones this season, a Hurricane in late August or early September and a tropical storm late in the season, say the last week of September
Since we need the rain I think we should hope for a couple of wet tropical storms.
For the two week period ahead I don’t see much forming in the Eastern Pacific. When we look at the wide angle surface chart there are no tropical waves in the pipeline, all the way back to the Sahara desert where they form. Tropical waves are nearly essential to the formation of tropical cyclones. That should give us 5-9 days with little chance of storm formation. Also, the ITCZ is still very depressed southward. The Coriolis Effect, which makes whirlpools and the motion of tropical cyclones, doesn’t have enough effect below about 8° from the equator and the ITCZ is just nudging above that mark now. Very early season storms can make a U turn and fall back on Central America, a rare event that has happened twice in the past 5 years and 4 times in the last 50 years. So, I think the next 14 days will be cyclone free.
But what do I know…!
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.
Saffir-Simpson Scale
Type |
Category |
Pressure (mb) |
Winds |
Winds |
Depression |
TD |
----- |
< 34 |
< 39 |
Tropical Storm |
TS |
----- |
34-63 |
39-73 |
Hurricane |
1 |
> 980 |
64-82 |
74-95 |
Hurricane |
2 |
965-980 |
83-95 |
96-110 |
Hurricane |
3 |
945-965 |
96-113 |
111-130 |
Hurricane |
4 |
920-945 |
114-135 |
131-155 |
Hurricane |
5 |
< 920 |
>135 |
>155 |