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My August forecast is the long-form forecast I have formulated over the past few years in written form. This forecast has not been published on Hurricane Wikia. This forecast uses proven factors in determining the numbers for the current hurricane seasons.

El Niño-Southern Oscillation (ENSO)

As of publishing date, the El Niño-Southern Oscillation (ENSO) has been in the neutral territory.[1] Moderate La Nina conditions were present in 2010, contributing to the large amount of tropical systems in the Atlantic basin and the anomalously low number of tropical systems elsewhere.[2] La Nina conditions weakened during the Northern Hemisphere (NHEM) Winter-Spring and eventually progressed into ENSO-neutral conditions. For a few weeks or months, Nino Regions 3.4, 3, and 1+2 went into positive sea-surface temperature anomalies.[1] These anomalies have since then moved back to the negative side, with Nino 3.4 and 3 experiencing anomalies up to -0.5 degrees. Many models keep ENSO-neutral conditions until at least MAM 2012. The Climate Forecast System (CFS) and CFS v.2 develop La Nina during the 2011 NHEM Fall. The Climate Prediction Center has issued a La Nina Watch, with the expectation of Neutral or La Nina conditions.[3] It is important to note that atmospheric conditions are still reflective of aspects of La Nina, even though ENSO-neutral conditions have persisted for a while. This ENSO information in the basin forecast reflects an enhancement of Atlantic tropical activity and a slight to noticeable suppression of East and Central Pacific basin activity.[1]

Sea Surface Temperatures

Sea Surface Temperatures are a major factor in forecasts. As of the current date, positive SST anomalies are present in the Atlantic and neutral to negative SST anomalies are present in the Eastern and Central Pacific basins.[4] Therefore, the basin forecast reflects an enhancement of Atlantic tropical activity and a slight to major suppression in Eastern and Central Pacific basin activity.

Climatology/Oscillations

We are currently in the midst of the Atlantic active era, which started with the hyperactive 1995 Atlantic hurricane season. The Atlantic Ocean Thermohaline Circulation (THC), which is associated with the Atlantic Multidecadal Oscillation (AMO), seems to indicate that it is still in the "strong" period. A phases of the THC (or the phases of the AMO) seems to have a correlation with tropical activity in the basins. If the THC is strong (positive AMO), then tropical activity is higher than average.[5] This information is reflected in the forecast by an enhancement of Atlantic tropical activity and a noticeable to major suppression of Eastern and Central Pacific basin activity.

Saharan Air Layer

The Saharan Air Layer for the Atlantic has prevented many waves to organize and intensify. The Saharan Air Layer is expected to continue to diminish its size by the time the peak of the Atlantic hurricane season arrives.

Current Activity

Atlantic

So far in the season, the Atlantic has produced seven systems, with all systems intensifying to tropical storm status. One of these systems remained as a weak tropical storm (35-40 kns), four of these systems intensified to a moderate tropical storm (45-50 kns) and two of these systems intensified to a strong tropical storm (55-60 kns). None of the systems intensified to a hurricane. ACE as of the publishing date is currently 13.3025.[6]

While seven tropical storms by August 16 is one month ahead of average, no hurricanes forming as of this date is behind climatology. It is also very rare that the first seven storms never reached hurricane status. ACE is average at 95% of climatology.[6] This current activity is reflected in the Atlantic forecast by increasing the amount of expected tropical storms, but this also slightly reduced the predicted amount of hurricanes and major hurricanes forming, and reduced the ACE percentages expected.

Eastern Pacific

This basin has just had a spectacular start to its season, with seven systems forming as of publishing date and six of them have progressed into a tropical storm. All of the first five storms reached hurricane status, and three hurricanes reached major hurricane status, with Hurricane Dora topping out just below Category Five intensity. ACE as of publishing date is 54.98.[6]

All of the first five systems reaching hurricane status is unprecedented. The amount of hurricanes is ten days ahead of climatology. However, the amount of tropical storm or stronger storms is 15 days behind average. The large amount of Major hurricanes already reached the average amount of major hurricanes in a single season. ACE, however, is only 95% of climatology.[6] This activity is represented in the forecast by increasing the amount of hurricanes and major hurricanes, and also increasing the ACE percentages for the season.

Central Pacific

No storms have crossed over or formed in the Central Pacific. However, Tropical Storm Fernanda might enter the basin after the publishing date.

No storms forming so far is not unusual. Current activity, based on Eastern Pacific activity, is slightly increased by increasing the amount of named storms in the basin.

Forecast tables

2011 Atlantic basin hurricane season forecast (August)
Named Storms 17
Hurricanes 8
Major Hurricanes 4
Accumulated Cyclone Energy 95-175
Accumulated Cyclone Energy Percentages 91-168%
Above-average season chances 85%
Average season chances 10%
Below-average season chances 5%
2011 Eastern Pacific basin hurricane season forecast (August)
Named Storms 14
Hurricanes 9
Major Hurricanes 5
Accumulated Cyclone Energy 80-160
Accumulated Cyclone Energy Percentages 61-122%
Above-average season chances 10%
Average season chances 65%
Below-average season chances 25%
2011 Central Pacific basin hurricane season forecast (August)
Named Storms 3
Hurricanes 1
Major Hurricanes 1
Accumulated Cyclone Energy 2-30
Above-average season chances 5%
Average season chances 45%
Below-average season chances 50%


References

  1. 1.0 1.1 1.2 "ENSO Cycle: Recent Evolution, Current Status and PredictionsUpdate" (PDF). El Nino-Southern Oscillation. Climate Prediction Center. 15. http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf. 
  2. "Extremely Active Atlantic Hurricane Season was a 'Gentle Giant' for U.S.". NOAA. November 2010. http://www.noaanews.noaa.gov/stories2010/20101129_hurricaneseason.html. Retrieved 16 August 2011. 
  3. "EL NIÑO/SOUTHERN OSCILLATION (ENSO) DIAGNOSTIC DISCUSSION" (HTML). El Nino-Southern Oscillation. Climate Prediction Center. 4. http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/ensodisc.html. Retrieved 16 August 2011. 
  4. "Tropical Pacific Sea Surface Temperature Animation" (Animation). El Nino-Southern Oscillation. Climate Prediction Center. 10. http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_update/sstanim.shtml. Retrieved 16 August 2011. 
  5. Philip J. Klotzbach; William M. Gray (3 August 2011). "FORECAST OF ATLANTIC SEASONAL HURRICANE ACTIVITY AND LANDFALL STRIKE PROBABILITY FOR 2011". Colorado State University. http://hurricane.atmos.colostate.edu/forecasts/2011/aug2011/aug2011.pdf. Retrieved 16 August 2011. 
  6. 6.0 6.1 6.2 6.3 Maue, Ryan. "Global Tropical Cyclone Activity Update". Florida State University. http://coaps.fsu.edu/~maue/tropical/. Retrieved 16 August 2011. 

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