Now that September is over, we can look back at a month that will be remembered for plenty of rain. Of course, it all depended on where you were: Gwinnett, Cobb and Douglas counties received far more precipitation than did the official measuring station at Hartsfield Airport. Still, it was the fifth wettest September on record in Atlanta, with 8.94 inches, or 219% of normal. It was the third wettest September in Macon with 10.68 inches, or 328% of normal, and the fourth wettest in Athens, with 9.86 inches, or 279% of normal rainfall.

At my house in Lawrenceville, I recorded 16.28 inches of rain, or 427% of normal rain. Gainesville reported 12.10 inches of rain, or 275% of normal, and Peachtree DeKalb airport had 15.74 inches of precipitation, or 420% of normal. The image above graphically displays the month’s rainfall. Click on it to enlarge.

Cooler than normal temperatures early in the month were balanced out with warmer than normal temperatures later on, ending up with a more or less normal average temperature for September. Atlanta’s mean temperature was 73.4 degrees, two tenths of a degree above normal. In Gainesville, the average of 71.0 degrees was 0.7 degrees cooler than normal, and in Athens, temperatures were half a degree above normal, with 73.1.

By now, even the most cynical will have to admit that the drought that plagued Georgia from 2006-2008 is finally over. A recent study by Columbia University indicated the drought wasn’t caused by global warming, and in fact wasn’t that unusual. The study says that the drought appeared more serious this time because of the Atlanta region’s growing population. While there was enough water for the region during similar droughts in the 1950s, not enough additional water storage was available to meet needs this time.

You may have noticed that it’s been a bit cooler than normal so far this April. As of this afternoon, the mean temperature for the month at Hartsfield Airport is 56.3 degrees, which is 3.6 degrees less than normal. Here in Lawrenceville, the mean is 56.4 degrees, not varying by much. Except on March 9th and 10th–when it barely made 80, we haven’t seen 80 degrees yet this year.

Normal temperatures for April 16th are a high of 73 and a low of 50. For the past few days, the highs have been in the mid-60s, with lows in the 40s. Much of the country has had a cooler than normal April, as you can see from the map below, which shows departure from normal temperatures for the first fourteen days of April:

It looks like we’ll have one more week of cool temperatures, before we start seeing 80 degrees by the end of next week. If you’re a fan of spring flowers like me, the positive side to the cool weather is that mother nature’s show lasts longer than normal. I remember in years past when a warm spell in late March brought out everything at once, and it was gone in a week. Not this year.

Today, the Climate Prediction Center updated its long-term outlooks for drought, May and the early part of the summer. North Georgia has mostly recovered from the drought, with only five percent of the state in moderate drought, and another two percent abnormally dry. The dry area includes the northeast portion of the state, but not metro Atlanta. Compare this to a year ago, when 54% of Georgia was experiencing drought conditions. Lake Lanier continues to improve as well, measuring 1062.76 feet above sea level, or over a foot above where it was a week ago.

The drought outlook through July show no signs of drought redeveloping, and calls for improvement in the corner of the state where drought still exists. The precipitation outlook, both for May and for May through July calls for equal chances of above or below normal rainfall for most of the United States. Above normal precipitation is likely for Minnesota and the Dakotas, while it is likely to be drier than normal in Utah and Idaho.

The temperature outlook for May and for May-July calls for equal chances of above or below normal temperatures east of the Mississippi, with warmer than normal weather in most of the southwest, and cooler temperatures in the same Minnesota-Dakotas area that is going to be wetter than normal.

The Climate Predication Center notes that we are entering a neutral period, neither in El Nino nor in La Nina sea surface temperatures. With neutral conditions, there are fewer reliable signals of what weather conditions will be, compared to either a La Nina or El Nino state.

Widespread March rainfall has caused all but a few North Georgia counties to become drought free. According to information from Georgia Climatologist David Stooksbury, the only counties still considered to be in moderate drought are Union, Towns, Rabun, Lumpkin, White, Habersham, Hall and Stephens. A few northwest Georgia counties are drought free, while the remainder, including Gwinnett, are classified as abnormally dry, mostly due to the long-term rain deficit we’ve experienced for the past four years.

Atlanta has recorded 7.12 inches of rain in March, over two inches more than normal. For the year, the deficit is 1.09 inches. With 7.03 inches of March rain in Athens, the Classic City is only .39 inches below normal for the year. With an additional inch or so expected Tuesday through Thursday, both cities could be back to normal rainfall by the end of the week.

While the plentiful precipitation seems to have encouraged Atlanta area flora to show their spring colors more strongly than in recent years, the hidden subtext of the drought picture, which I assume will be reflected in Thursday’s drought monitor, is that the counties that make up Lake Lanier’s drainage basin, including Hall and Habersham, are still in a moderate drought. Last week’s rainfall raised Lanier’s level by over a foot, but the lake is still ten feet below full summer pool.

The current climate pattern of a weak La Nina transitioning to neutral is responsible for much of the changes to a wetter spring. According to Stooksbury:

Currently the climate pattern is a weak La Niña pattern tending toward a neutral pattern. A typical weak La Niña spring brings wet weather across the northern piedmont into the mountains, just like north Georgia experienced in March.

Moisture conditions are in good shape across most of the state’s northern half, but the typical moisture recharge period will be ending soon. By the middle of April, plants are in full spring growth and using tremendous amounts of water.

By the middle of April we can expect the soils to begin to dry because of increased plant water use. Additionally, by the middle of April, temperatures are routinely in the 70s to low 80s. This means that evaporation will increase. This late spring and summer drying is normal.

The outlook is for a few more weeks of recharge followed by the normal drying of the soils due to plant water use and evaporation. May is usually a dry month. Little recharge is expected from May through October, but this is typical for Georgia.

The big unknown is what the tropics will bring Georgia this summer and winter. Much of the state’s late summer and fall rain comes from tropical disturbances. Without moisture from the tropics, August through October can be very dry. At this time there are no clear indications of how much rainfall the summer will bring.

Temperatures over the last few days have been 10 to 15 degrees above normal for this time of year. In the ‘typical’ early March, we’d be seeing a high of 63 and a low of 42. Things are about to switch around closer to normal, and then below normal for next week.

High pressure centered over south Georgia has provided the warm temperatures, and has blocked the colder temperatures and storms to the north from moving south. As the high pressure weakens on Wednesday, a cold front will sweep through, and by Thursday, temperatures will be noticeably cooler. By the weekend, wedging sets up, which will bring cloudy, cool damp weather to Atlanta and North Georgia.

All of this may clear out with a cold front coming through on Sunday, and after that, one more round of cold weather, with temperatures dropping below freezing after St. Patrick’s Day. It’s too early to know how cold it will get, but I hope you took my advice from last week to not put out any annuals. Both the 6-10 and 8-14 day forecasts call for colder than normal temperatures for much of the eastern US, and wetter than normal conditions for the southeast, especially early in the period.

Will next week’s cold weather be the last blast of Winter? In 2008, the last below freezing night was on March 25th, but in 2007, a late freeze in early April ruined the spring flower show.

Drought Update

Last week, the Georgia EPD announced that drought watering restrictions had been further reduced. Homeowners and businesses will now be allowed to use soaker hoses or drip irrigation three days per week for one hour per day, following the customary odd-even, midnight to 10 AM schedule previously used for hand watering. Hand watering will continue to be allowed for 25 minutes per day on the odd-even schedule.

The state’s intent here is to provide a means for homeowners to water shrubs and trees, rather than lawns. In face, lawns are specifically excluded from the EPD’s order (PDF). The interesting thing is that there’s no limit to the amount of soaker hose or drip irrigation that can be used – only a limit on the number of hours the system can run. The recommendation is that each soaker hose should be no more than 100 feet long, but by investing in a few of them, and possibly some faucet Ys, even someone with lots of landscape plants should be able to better this year than last.

Last week’s rainfall greatly reduced the intensity of the drought in Georgia, according to the latest update to the drought monitor, shown at right. Before last week’s rain, exceptional drought was the rule north and east of Gwinnett County, some 11% of the state. This week, no part of Georgia is in exceptional drought, and almost 70% of the state is drought free.

Only a small area of the state between Savannah and Brunswick increased in its rain deficit, going from normal to exceptionally dry. The newest outlook through March, 2009 calls for continued improvement for drought conditions in the southeast, and for drought to develop in the Florida peninsula and extend in Texas.

The updated drought outlook doesn’t square well with the latest long range outlooks from the Climate Prediction Center, released this morning. The temperature outlook for January is for warmer than normal east of the Rocky Mountains, except for South Georgia and Florida, which could be colder or warmer than normal. Below normal precipitation will occur south and east of a line from southern Louisiana to eastern North Carolina, more or less south of I-85.

For the first three months of the new year, warmer than normal temperatures are predicted east and south of a line from New Mexico to Wisconsin. Colder than normal temps are in line for the Pacific Northwest, with the Northeast possibly going either way. The three month rainfall outlook calls for above normal precipitation in the Ohio Valley, and below normal rain in the southeast.

Snow in Las Vegas

This has certainly been a month where snow has turned up in places you wouldn’t expect it to, and in record amounts. In addition to snow in Houston and New Orleans earlier this month, yesterday brought record snow to Las Vegas, Nevada. “Las Vegas Hits the Jackpot,” trumpeted the Weather Service’s record event report for Wednesday. The Las Vegas Weather Service office reported 3.6 inches of snow, the most ever in December, and the 8th worst snowstorm since recordkeeping began in 1937. Up to 7 inches of snow was measured in suburban Henderson, Nevada. In California, 5 inches of snow was measured in Boulevard, which is in interior San Diego County, and up to 20 inches of snow fell in the mountains to the east of Los Angeles. A light dusting was even reported in Malibu.

While Atlanta basks in what could be near-record temperatures today and Friday, the snow will continue to move north and east, setting the stage for a possible white Christmas, but not here.

The rain last week raised the water level of Lake Lanier about a foot, which likely means that Atlanta’s water supply won’t reach a record low in 2008. As usual, the mainstream media issued stories which said that the rain is good, but the drought isn’t over yet, we’ve got a long way to go, etc. &ct.

Now comes the Southeast River Forecast Center with the best estimate (PDF) I’ve seen for what it will take to get Lake Lanier to full pool — or 1071 feet above sea level, about 20 feet higher than where it is today.

Surprisingly, it’s only 10% above normal rainfall for a year.

The forecast center measured annual precipitation against Lake Lanier’s level since the lake began to fill back in 1952.  It determined that, on average, 60 inches of rain fell in the lake’s drainage basin per year, providing about 1.36 million acre feet of water.  Using those figures, and accounting for the fact that the Corps of Engineers has restricted the outflow from Lanier over the past year, the Forecast Center says,

Lake Lanier’s pool was at 1054 feet msl at the beginning of this water year (1.37 million acre-ft). To get to full pool at elevation 1071 feet msl, an additional 585,000 acre-ft of inflow is needed. However, this assumes no outflow. If we apply the annual average outflow of last year for this year (1070 cfs), 775,000 acre-ft are released downstream. So the total inflow volume needed to fill the reservoir and sustain a release similar to last year is 1.36 million acre-ft.
…[T]his would put the total annual precipitation at around 65 inches (following the lower end of the trend). This is only about 10% above normal.

Of course, part of the equation depends on when the water comes. If we get a lot of excessive rain in the winter, it will count more than if we get it in the summer, since the heat and absorption by plants prior to the water reaching the lake will be higher in the summer months. The calculations used in the analysis are based on rain during the water year, which starts on October 1, and there has already been six inches of rainfall. That means there are only 59 inches to go.

I listened to Lieutenant Governor Casey Cagle (who is clearly running to become governor in 2010) addressing the Gwinnett Chamber’s monthly meeting this afternoon. He dumped most of the problems with metro Atlanta’s water supply on the Corps of Engineers favoring mussels in Apalachicola Bay over the water needs of Georgia. He also offered an innovative idea for increasing the water available to metro Atlanta. He estimated 10% of the lake’s capacity had been lost due to silt (something I’m not going to argue with). By dredging the lake, Cagle says we could not only expand the lake’s capacity to hold more water, we could recycle and resell any valuable materials that were dredged up.

In my mind, Cagle’s plan will only work if Georgia gets some formal rights to the lake’s water. Based on court decisons and the official use plan for the lake, we aren’t there yet.

North Georgia has been blessed this year with a gorgeous few days of Indian Summer, traditionally defined as warm weather following a frost. Following a chilly end to October, November has been a delight, with temperatures more than five degrees above normal, which should be around 66. Of course, Indian Summer has its downside: a lack of rainfall. It’s been dry for the past two weeks, although that’s likely to change soon, as you’ll see below.

The dry weather hasn’t had much impact on the drought situation. The latest drought monitor doesn’t show much change from what we’ve seen since Labor Day. The latest drought outlook, released this morning, calls for some improvement in the short term, but paints a grimmer picture as winter settles in. The silver lining might be that the Lake Lanier drainage basin may get more precipitation than metro Atlanta proper.

As indicated by this post’s title, the mild weather we’ve had recently is going to come to an end, beginning tomorrow, when a cold front brings rain, and then cooler weather for the weekend. Following that, we’ve got a series of storms that are likely to bring rain several times over the next ten days or so. Temperatures are likely to seesaw during the period, with warmer weather during the week, and cooler weather on the weekends.

It’s all part of the battle between summer’s warmth and winter’s cold, with winter inevitably winning out as we move into December. The tropics are making a last stand as well. Hurricane Paloma has formed in the Gulf of Mexico, and appears to be heading towards Cuba as a category two storm, before recurving back out into the Atlantic, with no threat to the United States. Despite 17 Atlantic storms this year, Florida State University is reporting that overall, tropical activity in the Northern Hemisphere is down over the last two years, primarily due to a lack of storms in the Pacific. This is the lowest level of northern hemisphere storms seen in 30 years.

I almost hate to talk about it, in fear of creating a jinx, but it looks like the Atlanta area could get some rain starting late next week.  The last time we had any rainfall at all, either here or Atlanta Hartsfield was back on September 11th, when .01 inches was recorded.  That means we are at 23 days and counting without rain. Now, models are indicating a trough will begin to move from west to east, and could bring rain sometime Wednesday or Thursday.  It may not be one of these one hour wonders either.  Accuweather says that the rain will stick around through next weekend, bringing almost two inches by Columbus Day. The CPC extended outlook calls for above normal rainfall in the 6-10 day period and weather.com is less optimistic, with rain only on Wednesday or Thursday.

I did the annual fall aerating and overseeding for my fescue lawn two weeks ago, which means that I get a pass from the watering restrictions, and can turn on my irrigation system on the appropriate odd/evn schedule.  Even with watering, when I’ve dug a few holes to plant some new bulbs and shrubs, I’m amazed at how dry the ground is. The rain, if it comes, will be much appreciated.

Another thing we haven’t seen in a while is freezing temperatures.  While North Georgia typically doesn’t get its first frost until the second week of November, Michigan, Vermont and Maine are seening freezing temperatures over the next few days.  Nationwide, the lowest temperature this morning was 17 in Stonington, Michigan.  There’s a frost advisory tonight starting in Western Michigan and moving east through northen Ohio, much of northern Pennsylvania and southern New York.  And, snow has begun to fall in the Rocky Mountains, including areas of Utah and Colorado, where a few inches are predicted through tomorrow evening.

You can keep up with the approach of winter on our Winter Weather page.  It’s just a matter of time before we begin to feel winter’s effects here in Georgia.

It’s been almost two weeks since I’ve posted… partially because of some well-deserved vacation, partially because, at least here in North Georgia, a fairly quiet weather pattern, and partially because of some other interesting events taking up my web time.

So, what did we miss. After a few weeks of quiet on the tropical front, last week brought Hurricane Kyle, which was notable in that in the first time in 17 years or so, a hurricane made landfall in Canada. Right now, Subtropical Storm Laura is on her way to England, apparently, bothering no one, really. And then there was the storm that didn’t get named despite showing some tropical characteristics—including an eye, but brought rain to the Carolinas and up into the Mid-Atlantic states.

During all this turmoil, weatherwise and otherwise, the Atlanta area stayed dry.  I’ve recorded less than 2/3 of an inch of rain this month, and the official rain gauge at Hartsfield airport shows 3/4 of an inch, with no meaningful precipitation since back on the 12th.  That’s about 3 inches less than a normal September, although one only has to go back to 2005 to find less, when we only had a quarter of an inch.  The final total could change, since there are some storms in the area tonight, but it’s highly likely that we’ll go through another month with below-normal rainfall.

The two maps below show the tremendous difference a tropical system can make in dampening the effects of a drought. The map at left shows drought conditions in Georgia as of Tuesday, August 19th, when almost ten percent of the state was in exceptional drought conditions and only two percent was drought free. The right hand map shows conditions as of Tuesday morning the 26th at 7 AM. Now, none of the state is in exceptional drought, and 16% is drought free.

Remember, the cutoff for the drought maps was 7 AM Tuesday, which was before a good bit of the rain hit North Georgia, so I expect to see continued improvement with next week’s drought monitor as well. Lake Lanier has also risen just over two feet from the rainfall brought on by Fay.

The weather service has investigated the severe weather brought about by Fay, and has issued a report saying that there were six tornadoes in Georgia brought on by the storm. Most of the damage was in Hall and Jackson counties. Three EF1 tornadoes with 90 MPH winds were verified in Hall, where trees were knocked down and damage was reported to an elementary school.

Another tornado with 100 MPH winds touched down near Commerce in Jackson County, while two additional EF0 tornadoes with 70 MPH winds were reported in Monroe and Wilkes counties.

We may have some more opportunities for drought relief in the next week to 10 days. Gustav was a hurricane, and then was downgraded to a tropical storm when it made landfall in Haiti. It has moved a bit south, and is expected to increase in intensity to at least a category 3 hurricane. The media is comparing Gustav to Katrina, which hit New Orleans three years ago today. Despite the timing coincidence and the likelihood that Gustav will become an intense hurricane before it makes landfall sometime on Monday, it’s still too early to know exactly where the storm will make landfall. Recent updates to the forecast track have moved landfall west of New Orleans, and the further west it is, the less likely it will have any effect on the Atlanta area. A track further east, as some models are suggesting would make the storm more like Ivan in 2004, which brought intense rainfall to North Georgia.

And if Gustav isn’t enough, the Hurricane Center is now tracking Tropical Depression 8, located to the east of Puerto Rico. Later this afternoon, the storm will gain enough intensity to be named Hanna. Instead of moving south of Cuba as Fay and Gustav are doing, Hanna is likely to become a category 1 hurricane by Labor Day, moving north of the Dominican Republic and the Bahamas and heading west towards the Florida coast.

I suspect we’ll have a better idea of what both these storms will do as the weekend unfolds.