You may have expected it, but now the preliminary figures from the National Climactic Data Center are in, and they confirm that August 2007 was the second warmest on record for the country, and the warmest for Georgia and seven other southeastern states:

The average temperature of 75.4 degrees nationwide was 2.7 degrees above normal. In Georgia, the average temperature was 83.3 degrees, 4.0 degrees warmer than normal. Despite August being a record warm month for the state, the long-term temperature trend for Georgia is slowly dropping. The heat wave caused more than 30 all time temperature records to be tied or broken around the country, and more than 2,000 daily high temperature records were broken.

For precipitation, it was the 37th driest August on record, out of 113 years measured. Much of the southeast had below-normal rainfall, continuing the drought conditions we’ve had for the past year:

From looking at the map, it appears that Georgia had a relatively normal month, ranking 43rd dries, especially against the extremely dry conditions in the surrounding states. This is due to above normal rainfall in central and south-central Georgia, and normal rainfall in the southeast part of the state. The rest of the state saw below normal precipitation, with the northwest and northeast corners much below normal.

August was a record-breaking month in Georgia. In Atlanta, the first 26 days of the month had high temperatures above 90 degrees, and there were nine days where the temperature went above 100, tying a record set in 1980 for the most days in a year with temperatures above 100 degrees. For the month, the average temperature was 85.6 degrees, 6.7 degrees above normal. The high temperature of 104, set on August 23rd, was not only the record-breaker for the day, but for the entire month. You would have to go back to 1980 to see temperatures this warm.

Here in Lawrenceville, the average temperature for August was only 81.3, and the warmest day was the 9th, when the temperature reached 101.5. That’s still warmer then normal. One reason the average temperature was cooler than in Atlanta is that on many days, the overnight low temperature stayed lower than in the city. I recorded six days with overnight lows less than 70, while Atlanta recorded none. In Gainesville, the average temperature was 84.6, 7.1 degrees above normal, and in Athens, the average was 85.2, 6.9 degrees above normal August temperatures in the Classic City.

Believe it or not, but the official precipitation records for August 2007 in Atlanta will show the city received 95% of its normal rainfall of 3.67 inches. 3.48 inches of rain was recorded at Hartsfield-Jackson Airport during the month, but over two inches of that occurred in the last four days of the month, and most of the rest during the last week. Because August rainfall is typically driven by thunderstorms, the amount of rain you got depended on where you were. I recorded a scant 1.52 inches during the month, while Athens recorded less than half its normal monthly total, with 1.72 inches. Gainesville had 3.17 inches of rain during August.

September is a month of rapid change climate-wise, as we begin to see shorter days and lower daytime and evening temperatures. This month, however, is likely to be warmer than normal, with the Climate Prediction Center calling for at least a 33% chance of a warm September, and an even greater likelihood of hot weather for the southeast corner of the state.

Things are busy in the tropics, by the way, with three active named storms. In the Eastern Pacific basin, Gil is beginning to lose strength, while Henriette is expected to gain strength, and eventually bring wet weather to the southwest US. In the Atlantic, Felix became a named storm this morning. He looks like he is going to follow roughly the same path as Dean did, but track slightly to the south.

No one is going to argue that August’s heat wasn’t brutal. Here in Lawrenceville, there has only been three days when the high temperature has been below 90 degrees, and two of those were at the beginning of the month, before the heat wave got started. In Atlanta, every day has been above 90, more than seven degrees above normal. Normally, Atlanta will only get 36 days with temperatures 90 degrees or higher, and according to some historical data I saw on the National Weather Service website, this may be the longest streak of 90+ degree days ever.

The pattern change that began late last week will finally get temperatures below 90 again, but we may have to wait until September 1st to get there. The movement of the surface and upper-level high pressure systems to our west allowed moist air from the Gulf of Mexico to come into north Georgia, and has been responsible for the afternoon thunderstorms over the weekend. These will probably continue through the week.

By the next weekend, a ridge in the western United States, and a trough along the east coast should cause a northwest flow, which should bring cooler temperatures to much of the southeast. The Weather Service’s long-range outlook from September 1st through 5th calls for cooler than normal temperatures from Texas to the New England States. Of course, everything is relative. I’ll still be happy to see temperatures back towards normal, with highs in the mid 80s and lows in the mid 60s.

Update: I apparently posted this too early, as the weather service came out with new numbers for the high temperature. The official high for Atlanta reached 104 degrees at 5:21 PM, making Wednesday the warmest day recorded since July 17th, 1980, and marking the third-warmest day ever recorded in the city, and the all-time high for August.

The day’s record also means Atlanta has tied the 1980 record for maximum number of days above 100 degrees with nine. How’s that for setting a bunch of records in one day?

Back to the original post…

Atlanta’s official temperature gauge at Hartsfield-Jackson airport recorded another record high today, with 102 degrees, breaking the previous 1983 record of 100. Here in Lawrenceville, the high reached 101. Also this morning, Atlanta recorded another ‘high-minimum’ temperature of 79 – meaning that the low temperature for August 22nd was the highest it had ever been for this date.

The good news is that today is probably the last of the 100 degree days for the season, and a change in the weather pattern is on the way, albeit slowly at first.

The weather we’ve had over the past two weeks has been controlled by a strong high pressure system, both at the surface and aloft. Since high pressure causes air be heavier than air of lower pressure, it acts to reduce air movement, and keeps storms away. Even Hurricanes Dean and Erin were affected by this. Note how the remnants of Erin moved way north to Michigan and Ohio before turning back eastward. And, a silver lining of the ridge is that it has also kept higher humidity away, keeping the heat from becoming unbearable.

Anyway, the high pressure ridge is ever so slowly moving to the west, and after tomorrow, we should start to see cooler temperatures and an increased chance of sorely needed rainfall. Highs next week should still be warmer than normal, but only in the low 90s, with a chance of thundershowers most days. The chance of rain should be even stronger by this time next week. Accuweather is forecasting rain every day from September 1st through 4th, although this is pretty far out.

At this point, though, I’m more worried about the drought than the heat. You know it’s dry when even the weeds are dying back.

The National Hurricane Center has officially recognized Tropical Depression Four, which lies in the mid-Atlantic with winds of 35 MPH. It is expected to become Tropical Storm Dean sometime on Tuesday morning. and is projected to become a hurricane by the weekend, when it may be close to the Virgin Islands, headed towards Cuba.

You can view the storm’s projected path here, and view a satellite image here.

At this point, it’s too early to tell where the storm will ultimately make landfall, short of saying it will probably be somewhere in the Gulf of Mexico.

Atlanta’s hot weather got a break on Sunday, when a summertime version of the wedge brought east winds, and cloud cover that lasted through mid afternoon, and kept high temperatures in the 80s. After four days of record-setting heat (another temperature record was broken on Saturday), I’m sure everyone enjoyed the break. We could see more records broken this week, with high temperatures in the upper 90s through Friday. By that time, we’ll be in a better position to see what effect Dean will have on Georgia.