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HURRICANELONNY wrote:That sounds about right to me. That is some good stuff that Ed researched. I think the NHC jumped the gun this year. No neutral this season. All La Nina. It seems to me it coincides more with 98. Not 2005. My guess is 15 storms. Not including Alex. I guess that means 16.
This outlook reflects an expected set of conditions that is very conducive to increased Atlantic hurricane activity. This expectation is based on the prediction of three climate factors, all of which are conducive historically to increased tropical cyclone activity. These climate factors are: 1) the tropical multi-decadal signal, which has contributed to the high-activity era in the Atlantic basin that began in 1995, 2) exceptionally warm sea surface temperatures in the tropical Atlantic Ocean and Caribbean Sea (called the Main Development Region), and 3) either ENSO-neutral or La Niña conditions in the tropical Pacific, with La Niña becoming increasingly likely. In addition, dynamical models forecasts of the number and strength of tropical cyclones also predict a very active season.
HURRICANELONNY wrote:I think it will be above normal this year. I just don't see 18+ names. Most sites never predicted 2005. Maybe they're just covering there ass. In case it happens again. I don't think all the variables that were in place in 05 are here this year. All I'm talking about is #'s. If I get wiped out by a major and that was the only landfall. It was a bad year.
Posted by: JeffMasters, 1:16 PM GMT on July 15, 2010
The equatorial Eastern Pacific Ocean continues to cool, and we have now crossed the threshold into La Niña conditions. Sea surface temperatures (SSTs) over the tropical Eastern Pacific in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region", fell to 0.8°C below average by July 12, according to NOAA.. The Australian Bureau of Meteorology put this number at 0.7°C below average (as of July 11.) Since La Niña conditions are defined as occurring when this number reaches 0.5°C below average, we are well into the territory of a weak La Niña event. La Niña conditions must be present for several months before this will be officially classified as a La Niña event, but it is highly likely that a full-fledged La Niña event lasting at least eight months has arrived. We started out the year with a strong El Niño, so it may seem surprising that we have transitioned La Niña so quickly, However, historically, about 35 - 40% of El Niño events are followed by a La Niña within the same year. Given current trends, I expect the current La Niña to cross the threshold needed to be defined as "moderate" strength--temperatures at least 1.0°C below average in the equatorial Eastern Pacific--by September.
The implications
It is well-known that both the number and intensity of hurricanes in the Atlantic tend to increase during La Niña events. However, as I discussed in a post last month, since 1995, neutral years (when neither an El Niño or La Niña are present) have had Atlantic hurricane activity equal to La Niña years. The last time we had a strong El Niño event followed by a La Niña event in the same year, in 1998, we had a Atlantic hurricane season 40% above average in activity, with 14 named storms, 10 hurricanes, and 3 intense hurricanes. The season was relatively late-starting, with only one named storm occurring before August 20. I'm thinking this year's season may be similar, though four or more intense hurricanes are a good bet due to the record warm SSTs.
Both El Niño and La Niña events have major impacts on regional and global weather patterns. For the remainder of July and August, we can expect La Niña to bring cloudier and wetter than average conditions to the Caribbean, but weather patterns over North America should not see much impact (Figure 2.) Globally, La Niña conditions tend to cause a net cooling of surface temperatures. Thus, while the past twelve month period has been the warmest globally since record keeping began in 1880, it is unlikely that the calendar year of 2010 will set the record for warmest year ever.
cycloneye wrote:One more signal that La Nina is here,is the SOI index that continues strongly in positive territory. The holdout for declaring ENSO officially in La Nina status is Climate Prediction Center, but as I posted last week, they said in the last bulletin La Nina will be declared by late July or in August. The pending question is how strong this La Nina will be,but some ENSO models are very bullish on a moderate to strong La Nina.
Daily SOI Values
http://www.longpaddock.qld.gov.au/seaso ... /index.php
Daily 30 day SOI Text
http://www.bom.gov.au/climate/enso/soi.txt
Summary
Following the dissipation of the 2009/10 El Niño in early May 2010, a brief period of ENSO-neutral conditions was observed until mid-June, when weak La Niña conditions emerged. For the July-September season currently in progress, there is an approximately 80% probability for continuing La Niña conditions, and a 20% probability for returning neutral ENSO conditions. Probabilities for La Niña conditions continue at approximately 80% through the remainder of 2010.
General Discussion
By mid-July, the NINO3.4 SST anomaly index decreased to values indicative of weak La Niña levels (roughly three-quarters of a degree C below average). Zonal wind anomalies in the equatorial Pacific have featured slightly stronger than average easterlies, and subsurface heat content became well below average by mid-May as the El Niño rapidly ended, soon to be replaced by the current weak but strengthening La Niño conditions.
Out of a large set of dynamical and statistical prediction models, 82% indicate maintenance of La Niña conditions during the upcoming July-August-September season, while 18% indicate a return to ENSO-neutral conditions. Overall, based on model predictions and current observations of the ocean surface and subsurface, for the coming August-October season and throughout the remainder of 2010 the probability for La Niña conditions is estimated at near 80%, and for ENSO-neutral conditions approximately 20%. Probabilities for a return to El Niño conditions are negligible through early 2011.
But activity for this season has been normal (even above normal) thus far: A Cat2 hurricane, a TD and a TS.KWT wrote:Looking like its going to be a solid moderate, which probably explains partly why the first the first few months of the season may have been so slow...
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