User blog:YE/2014 Pacific hurricane season August outlook

Extreme levels of activity
Obviously, the East Pacific has been a very very busy place so far this year. Here is this years stat line: 2014	11	6	5	85	7.7

Pretty good, right? Well, that doesn't really tell the big story. It's the intensity that the season has. It just feels different. Conditions are just very favorable as of late. Somewhat low wind shear, warm waters, fairly moist air. The cooling of Nino 1+2 may have increased shear a little, but it seems to have relaxed as of late. Instability is fine, waters are warm, we were just waiting for some Kelvin Wave/MJO activity which occurred a few weeks ago. And since then, boy the season has taken off and shifted into high gear. And since then, we've got madness, pure madness. Iselle being an epic long tracker that somehow found a way to hit Hawaii from the east - a first since 1993. Genevieve was an epic long tracker that bombed out near the WPAC and became one of 3 EPAC systems to become a Cat 5 in the WPAC. Even Julio doing something that was common in the generation before this (aka as the glory days of the 80s and 90s) but rare now, and that is to make it to a high latitude. The immediate future of the basin looks bright, with a possible 1-2 system this week, and additional activity likely thereafter.

All in all, the season has meet its loft preseason expectations, or in some cases, has exceeded it. While we have yet to receive a Category 5 hurricane, otherwise, this season has yet to disappoint. We have had set many active era records, including fastest 10 storm start (Hernan, July 26), earliest 2nd major (Cristina), earliest 2nd Cat 4 (also Cristina). This is on track to be one of the most active on record, and the most active on record.

Comparisons
Let's take a look at the top 5 active EPAC seasons on record for a moment and compare them to 2014

So, what does the above chart mean? It means 2014 is hanging up there with one active active Eastern Pacific hurricane season of all time. So just basing it on that, we should expect the season to have over 20 storms. But this aint the 1980's baby! Let's include, you know actual factors in this outlook.

Discussion
So, let's get right to it. Wind shear, which was as previously mentioned above on the rise, has dropped a bit. The reason why it dropped has to do with Nino region 1+2, which dropped off significantly, due to an upwelling phase of a Kelvin Wave that has reduced the chances of a traditional El Nino event. Nino 1+2 cooled arguably the most, and as result, we entered a Modoki-El Nino like pattern. This confirms a longtime question on what does a Modoki El Nino do? It increases shear over the EPAc, rather than the Caribbean. While I still somewhat doubt we'll see a Modoki (based on the unimpressive Nino 4 SST anomalies), it does explain the lack of activity in the EPAC in 2004.

However, this increase was short-lived, and while enough to make the first 3 weeks of July dull, shear eventually diminished markedly in early August. This combined with the earlier passage of Kelvin Wave, and a weak MJO pulse helped the lid come off the EPAC, and allowing it to go bonkers since the end of July.

What does this mean for the future? In the long range, I'm not fully sure; however, I will like to put out that this increase in shear occurred despite MJO's help, a somewhat impressive accomplishment. I see no reason for shear to increase, and the GFS shows low wind shear in the EDR right off the south coast of Mexico, where there currently is a moderate shear that hindered Iselle and Julio from developing early on and is also slowing 99E's development to a certain extent. So, based on the above GFS forecast, I'd expect a climatological decrease in shear off the Mexico coast, setting us up for landfall season.

Vertical instability is well above average, unlike the Atlantic for the last several years, and like most El Nino years. SST's are above average as well, PDO was remained positive, and there's a chance of an El nino event soon. Things are shaping up to very active season much like it's been thus far. There is no reason not to believe there will be less than 20 storms this season, and in my forecast below, I am calling for me, with high confidence of such pick. MJO or not, there is nothing stopping the EPAC right now.

I do not like to doomcast, but I will say there is an increased risk of a significant landfalling hurricane along the west coast of Mexico in September or October, like many El Nino seasons. There is a good agreement in a few weeks within the long range CFS runs that we should see a track shift from most TC's forming between 115W and 130W to most systems forming off the west coast of Mexico. SST's there are quite warm, with a band of 30-32C anomalies that extends for several hundred miles west of the Mexico coast and into the Gulf of California. If we can get a low wind shear environment, which we should, and a storm to form over these SST's, we could get a truly deep tropical hurricane and a possible serious threat to the Mexico coast, much like Hurricanes John and Lane in 2006, and Hurricanes Jimena and Rick in 2009.

Another thing worth noting is the US state of California, which is at a slightly higher than normal risk. Although SST's are very very cold up there as usual, shear is lower than normal up there, and SST's are a little higher than average.

One factor that I noted could be inhibiting development last month, does not appear to be much of an issue. The MJO which has been quite incoherent and borderline dead over the past several weeks, is likely to intensify somewhat and could possible move back into the EPAC at a higher amplitude in late August/early September, similar to what we saw around this time of year in both 2012 and 2013. This could help sustain activity as we get into September, as well as the possible increase in Kelvin Waves as the Pacific warms.

El Nino
Now, this is a pretty interesting topic if you ask me. Will we get an El Nino? I still think it's fairly likely, but there is high uncertainty. According to the CPC, SST's anomalies in Nino 3.4 are at +0.0C. The BOM and JMA suggest slightly higher value, but remain below the +0.5C threshold for a Nino to be declared. It may be getting too late, but models are still in pretty good agreement that an El Nino will develop. In addition, we have a new warm pool building below the surface in the CPAC, a second warm pool that is key to the development of an El Nino. In addition, last season featured an unusually high number of landfalls. Similar years that featured such pattern? 2003, 2008, 1981, 1971, and 1996. Guess what formed after those years? An El Nino. Guess how much rain fell in California those winters? A lot. In addition, this ENSO event has something it hasn't for ages, consistent -SOI values for the past 4-6 weeks. This should help spark some Westerly Wind Bursts, which allow for warm SST's be pushed towards 130W, or in cases of many super El ninos, the coast of Peru.

I will also note that from a statistical point of view, if we get no El Nino, it was very likely we will get one next year.

Even if no El Nino occurs, given the otherwise very conducive conditions, there would little need to change the numbers of this forecast below.

Summary
All in all, I increase my numbers to 21 named storms, 11 hurricanes, and 7 major hurricanes. Based on trends, I expect ACE to be around ~160 units, in the above average category. If my forecast verifies, we have the most active season since 1992 on our hands.

I will also lastly like to point out that if we keep up with 1992's activity, we could theoretically reach the Greek Alphabet. No EPAC seaosn, even 1992 has done this. Due to its low odds, I do not expect this to happen not to mention the fact we are in an inactive cycle (Generation VI) of EPAC activity. Which raise sup another question, has the inactive era ended? Are we in Generation VII now? If you ask me, it is too soon to say, but I'm wiling to admit it's possible. Is the +PDO a new trend of a temporary blip? We don't know what causes PDO to flip, so to be honest, I really don't know.

YE Pacific  Hurricane  05:14, August 12, 2014 (UTC)