Summer 2013 Climate Summary: Much Wetter & Slightly Cooler than Normal

The summer of 2013 was marked by much wetter than normal rainfall conditions and this led to slightly cooler than normal overall average temperatures across most of Northeast Florida and Southeast Georgia. Many of the climate locations reported fewer 90 degree or higher days than normal in combination with an above normal number of days with measurable rainfall this summer. For this report, Summer is defined as the months of June, July and August. Specifically for Jacksonville, after the much warmer than normal summers of 2010 and 2011, the past two summer of 2012 and 2013 have brought slightly below normal temperatures. This summer the reason for the pattern shift was due to an unusually persistent Eastern U.S. trough axis in the mid levels of the atmosphere and this brought a predominately SOUTHWEST steering flow across the local forecast area. For most of the summer this allowed for morning showers and storms to develop over inland areas of Northeast Florida along the Interstate 75 corridor and track towards the northeast and impact Coastal Northeast Florida and Southeast Georgia during the early afternoon hours. The earlier start to the convection most of this summer held maximum temperatures down slightly below normal levels. In fact, none of the four climate sites reached the upper 90s this summer, with all of them topping out at 96 degrees for their summertime maximum temperature. Late in the summer, several weakening cold fronts traveled across the Southeastern U.S. and washed out across the forecast area, and this allowed for heavy precipitation to focus in several river basins, including the Altamaha, Satilla, Suwannee and Santa Fe where widespread minor to moderate river flooding occurred. In fact, the Alapaha River at Statenville, GA even reached major flood status in August. The unusual weather conditions even impacted the Jacksonville Metro Area, where an EF1 tornado touched down in the eastern suburb of Arlington on August 1st, producing extensive structural damage to buildings and homes, but only one injury was reported.

The FIRST graphic below shows total rainfall amounts over the past 90 days from early June to early September across the region. As reported by the climate stations of Gainesville, Alma and St. Simons Island and can be seen in the graphic most locations reported between 20 and 25 inches of total rainfall, about 5 to 10 inches above normal. Along the Altamaha River basin of inland Southeast Georgia about 20 to 30 inches of rainfall was reported this summer and contributed to river flooding there, including the fact that Alma received its 2nd wettest summer on record with 24.21 inches of rainfall. While the impacts of the SOUTHWEST steering flow can be seen along the I-75 corridor of Northeast Florida and the Suwannee River Basin where widespread 25 to 40 inch rainfall totals can be seen, with a few isolated rainfall totals pushing 50 inches. As can be seen in the SECOND image below, two separate areas where rainfall departures as much as 10 to 20 inches above normal occurred across the Altamaha River Basin of Inland Southeast Georgia and the Suwannee River Basin of Inland Northeast Florida just west of the Interstate 75 corridor. While the infamous "Jacksonville Split" shows rainfall amounts closer to normal values across much of the Jacksonville Metro area. Gainesville recorded its wettest July on record with 16.65 inches, but was followed up by its 7th driest August on record to record a total of 25.70 inches for the summertime months.

Jacksonville, FL (JAX): Yesterday's 90-Day Observed Precipitation Valid at 9/6/2013 1200 UTC - Created 9/7/13 0:11 UTC

Jacksonville, FL (JAX): Yesterday's 90-Day Departure from Normal Precipitation Valid at 9/6/2013 1200 UTC - Created 9/7/13 0:14 UTC

Summer 2013 (Jun/Jul/Aug) Average Temp Summer High Summer Low # of Days >= 90F   (vs Avg) Summer Total Precipitation # of Days  with Precip  (vs Avg)  Highest Daily Max Precip Highest Wind Gust
Jacksonville, FL 80.9 F (-0.5 F) 96 F on 6/13 68 F on 6/16 44 days (-13 days) 19.12" (-0.78")     47 days      (+4 days) 2.18" on  6/6 53 mph on 8/31
Gainesville, FL 81.4 F (+0.8 F) 96 F on 8/12 68 F on 6/22 62 days (+7 days) 25.70" (+6.12") 19th Wettest
46 days (Normal) 3.55" on 7/31 44 mph on 7/5
Alma, GA 80.6 F (-0.4 F) 96 F on 6/12 65 F on 8/28 57 days (-2 days) 24.21" (+8.05") 2nd Wettest   52 days    (+15 days) 2.66" on 8/15 47 mph on 6/26
St. Simons Island, GA 81.5 F (-0.2 F) 96 F on 8/13 71 F on 8/26 19 days (-16 days) 22.52" (+7.33") 10th Wettest
   39 days     (+6 days)
2.40" on 8/15
43 mph on 7/22

Jason Hess - Climate Focal Point -

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