In July, multiple low-pressure systems formed over the eastern Gulf and moved across the northeast part of the state into the Atlantic Ocean; this resulted in large swaths of above-average rainfall over the western areas of FFS Region 3, the southwestern areas of FFS Region 2, and the northwestern areas of FFS Region 4. Some of the surpluses seen in these areas were around 8” to 12” with areas of flooding occurring around Tampa at the end of the month and into early August. July has seen temperatures around average for the Florida peninsula and slightly above average for the northern areas of Florida, while August has brought roughly average temperatures throughout the state.
In August, upper-level disturbances allowed for multiple frontal passages through the northern areas of the state, which is quite unseasonal for this time of year. This allowed many areas of northeast Florida to receive above-average rainfall. Additionally, storms and showers continued to be seen over western areas of the Florida peninsula and western Big Bend regions, which continued to supply these areas with above-average rainfall. The largest rainfall deficits in August were centered around the coastal areas of D-17.
In September, remnants of tropical systems assisted in bringing above-average rainfall to the majority of the Florida peninsula and northeast Florida. Additionally, unstable air from weak upper-level troughing and moist vertical profiles aided in providing favorable conditions for a wet September over FFS Regions 2 – 4. FFS Region 1 saw the least amount of rainfall in September with areas west of the Apalachicola River seeing the largest deficits, resulting in relatively dry conditions in D-1 and D-2 in FFS Region 1. El Niño conditions have been seen for the previous three months and have resulted in wetter conditions and few tropical cyclones.
Many areas of the Florida peninsula saw above-average rainfall in the past three months, and these conditions have stemmed from low-pressure waves that form near the tropics and/or the Gulf that have been sheared apart from the subtropical jet stream that is strengthened by the current El Niño event.
Long-Range Weather Outlook
Looking ahead in the next three months, the NOAA Climate Prediction Center (CPC) is currently forecasting above-average temperatures for most of the state with the greatest chances occurring in south Florida. There are equal chances for below-normal, normal, and above-normal temperatures in the Florida panhandle west of the Apalachicola River. Additionally, the CPC is forecasting above-average rainfall over the next three months with the greatest chances occurring south of FFS Region 2. This may indicate the presence of additional rainfall coming from the tropical areas such as weak subtropical low-pressure waves that bring Florida warm, moist air masses with widespread rainfall or from moist, convective activity moving in from the west over the Gulf due to an enhanced subtropical jet stream from the current El Niño event.
Upper-level convective support from the polar jet stream could help increase the rainfall chances in north Florida over the next three months. However, this scenario would usually involve the presence of a cold front, which is currently not being reflected in the three-month temperature outlook. Hurricane season does not technically end until December, although strong El Niño patterns have been discouraging Atlantic tropical weather systems.
El Niño conditions are currently present at this time and are currently forecasted to last throughout the winter and possibly weaken going into spring 2016. This could assist in supplying Florida with above-average chances of rainfall for this winter. High sea surface temperature (SST) anomalies are currently being seen in the equatorial Pacific Ocean and could help support high rainfall events over Florida later this winter.
Summary and Fire Potential Outlook
Overall, above-average rainfall over the Florida peninsula in the last couple months has left FFS Regions 2 – 4 quite saturated and has resulted in low KBDI values throughout these regions. Below-average rainfall over much of the Florida panhandle is currently causing dry conditions with many areas of FFS Region 1 seeing KBDI values over 500. Above-average temperatures are expected over the next three months throughout the state with the greatest chances over south Florida, which means that the state could see a warm start to the winter later this fall.
Above-average chances for rainfall are present throughout the state with the greatest chances occurring in the southern half of the state. The combination of above-average rainfall and above-average temperatures being forecasted over the next three months could indicate that the majority of our rainfall events will originate in the tropics and/or the Gulf of Mexico instead of frontal systems that make their way from the north, via the polar jet stream.
The El Niño conditions over the equatorial Pacific are forecasted to continue throughout the fall and winter and will perhaps weaken going into spring of next year. Responses to the El Niño have been seen with above-average rainfall for many portions of the state along with an inactive tropical cyclone season. Although above-average temperatures are forecasted over the next three months, models do indicate that below-average temperatures may be seen as early as January, which would better reflect the current El Niño scenario.
The next seasonal outlook will be the first week in January 2016.
Drought Outlook (NOAA)