Fire Weather Outlook: July- September, 2010

Updated July 8, 2010

CURRENT CONDITIONS

Highlighting the difficulties that exist in predicting transition out of El Niño/Southern Oscillation (ENSO) phases, sea surface temperatures (SSTs) plummeted dramatically in May along with a sharp increase in trade winds. This signals the end of El Niño conditions in the tropical Pacific. We now exist at the cold end of neutral conditions, and development of La Niña conditions this summer is apparent. With conditions very near the La Niña threshold, there is a possibility it may be in the next month.

In Florida, temperatures have shifted in the last couple months to being warmer than normal. With the arrival of a summertime pattern, rainfall trends – like afternoon convection - are a patchwork across the state; some areas saw significantly above normal precipitation, some were near normal and other areas received very little rain at all. For the state as a whole, precipitation has been near to below normal.

LONG-RANGE OUTLOOK

With a large cold anomaly in the tropical Pacific, the emergence of La Niña conditions appears all but certain. ENSO models predict the continuation of these conditions, and the development of a full La Niña episode this winter. This will have some impact on conditions this summer and fall, but a La Niña event will have its strongest influence in the winter. For the next few months, a continued tendency for above-normal temperatures looks to exist.

An increased likelihood of above normal precipitation exists for the next few months – this is partly due to the increased probability of an active Atlantic hurricane season. Seasonal forecasts from reliable organizations unanimously predict an active season, due to the end of El Niño conditions, record-high oceanic heat content, and other predicted favorable conditions. The Atlantic hurricane season is already off to an impressive start; with Category 2 storm Alex being the first June hurricane since 1995, the first landfalling June hurricane since 1986, and the first storm to reach Category 2 in June since 1966. It is impossible to predict with measurable skill if any storms will impact Florida. However, as the state most impacted by tropical weather, an increased amount of activity implies an increased threat of a storm making landfall in Florida.

SUMMARY

El Niño conditions in the tropical Pacific have ended and are rapidly transitioning to La Niña conditions. Emergence of La Niña conditions is favorable this summer and potentially in the next month. La Niña effects, as with El Niño, are typically most apparent during the winter months. Temperatures in the last couple of months have been above normal, and in some places, the warmest on record. Statewide, precipitation has been about normal, but there are places that have seen well above normal and well below normal precipitation.

Over the next few months, there is an increased likelihood that Florida will continue to see above normal temperatures. There is also an increased likelihood that Florida will see above normal precipitation. These wet conditions are forecast to result in lower significant fire potential for the state. Part of the reason for the increased chances of wet conditions is due to a forecast of an active Atlantic hurricane season. While forecasting where systems will impact is not at an advanced stage, an increase in the number of storms implies an increased chance Florida will see direct impacts from a tropical cyclone. Indirect impacts, such as rains caused by an influx of tropical moisture due to a distant storm have already occurred with Hurricane Alex, and are likely to happen again.

The next seasonal outlook will be the first week in October, 2010. Should there be any questions, please contact luchss@doacs.state.fl.us

Florida Department of Agriculture and Consumer Services

Download Document Viewers