Back on Christmas, I posted that 2007 was not going to be the driest year ever recorded in Atlanta, given the Christmas rains. I also quoted the record as having been set in 1931.  Well, reviewing my sources, I found I was half right.  The 1931 amount was for rain through December 12th, not December 31st. They must have had more than two inches of rain in the last three weeks of December that year, because the actual record for the entire year is held by 1954, with 31.8 inches of rainfall.

With the good soaking we got on Friday, Atlanta’s rainfall total now stands at 30.55 inches for the year, or 1.26 fewer inches than the record amount of 1954.  There’s a reasonable chance that we’ll see that much tonight and tomorrow, but it really depends on where the bulk of the precipitation falls. Right now, a surface front lies across Georgia from southwest to northeast.  The exact position of the front will determine the amount of rainfall we see, but the HPC is calling for a band of two inch rainfall roughly between Columbus and Greenville, SC.  It may very well be that since Atlanta’s official rain gauge is at Hartsfield Airport on the southside, where more rain is expected, the record will be avoided.

In any case, the rain is welcome, although it’s going to be followed by colder weather to usher in the new year. Look for temperatures in the low 20s Wednesday morning, and highs only in the 40s on Wednesday.  By Thursday, we start returning to more normal temperatures, and even above normal temperatures for the first two weeks of the new year, with high temperatures reaching into the 60s, 15 degrees above normal. Lows should be in the 40s, also well above what we would expect to see in early January.

Meanwhile, tropical weather may be getting ready to make a late season appearance.  The National Hurricane Center is reporting that a low pressure system 950 miles southwest of the Azores is developing tropical characteristics, and could become a subtropical storm by Sunday morning.  We already had  Subtropical Storm Olga make a late appearance in mid December, so something is not out of the question.

As much of the southeast US enjoys record setting temperatures in December, maybe it’s only appropriate that a late subtropical storm make an appearance in the Caribbean Sea.  Subtropical Storm Olga is being tracked by the National Hurricane Center, and is making landfall over the Dominican Republic:

Don’t expect any drought relief from Olga, though.  Although she could drop up to a foot of rain over Santo Domingo, by Wednesday afternoon the storm will have become a tropical depression, and the remnant low will be over the Yucatan peninsula by the weekend.

Meanwhile, metro Atlanta is enjoying its third straight day of record warmth.  With the temperature already at 75 degrees, we’ve broken the old record for December 11th of 73, set back in 1985.  Yesterday’s high of 77 degrees broke the old record of 74, which was set in 1972, and Sunday’s high of 76 topped the previous record of 71 degrees in 1978.

Look for more warm temperatures through Thursday, when the high pressure system holding off the storms to the north will start to break down and bring in at least some rain.  By the weekend, it will feel more like winter, with highs in the upper 40s to low 50s.

While the 2007 hurricane season doesn’t officially end until Friday, for all intents and purposes it’s over, with no activity since the beginning of November, and nothing on the horizon.  Despite predictions for an active season, 2007 ended up being about normal.  Dr. Gray and the gang over at the Department of Atmospheric Science at Colorado State University have released their 2007 summary (PDF) with the numbers for the season:

We had 14 named storms, with six hurricanes and two intense hurricanes this year. Dean and Felix ended up as category 5 storms, and both ended up on the Yucatan peninsula in Mexico.  The remaining hurricanes were category 1, or relatively minor.  For the second consecutive year, the United States went relatively unscathed, with only Hurricane Humberto striking Texas creating any significant damage.  Tropical Storm Barry brought some drought relief to parts of Georgia, and helped put out the south Georgia wildfires.  However, a storm that might have put a significant dent in the drought did not appear.

The Colorado State team seems to be at a loss to explain the weaker than expected season.  Some of the factors that would point to a stronger season, including the development of La Nina conditions and a relative lack of vertical wind shear worked out as expected.  Atlantic sea surface temperatures were slightly cooler than predicted, but this should not have been a major factor.

While the first half of the season turned out to be relatively normal, less than normal activity in October and November counted for most of the shortfall from the earlier projections.   And, the report said that despite normal to lower-than-normal hurricane seasons in 2006 and 2007, we are still in a period of greater than normal hurricane activity that will last another ten to 20 years.  This long cycle is part of the Atlantic Multidecadal Oscillation that is also responsible for the southeast’s rainfall shortage.

As far as what 2008 will bring…well, Dr. Gray’s team plans to issue its first 2008 hurricane forecast on December 7th.

The low pressure system south of Haiti was upgraded to a tropical depression last evening, and this afternoon, was upgraded to a tropical storm.  Noel (pronounced Nole, by the way, not like the Christmas synonym) is presently 125 miles south of Haiti, and is headed towards Cuba.

Forecasters expect Noel to move northwest, and cross Cuba sometime Tuesday morning.  While the official forecast calls for winds to remain in the tropical storm range for the next few days, it’s not out of the question that it could intensify into a hurricane, either before or after crossing Cuba.

The ultimate path is still uncertain, and it’s possible that the storm could bring some rainfall to Georgia. It’s worth keeping an eye on.

Another thing worth keeping an eye on is the nighttime low temperatures over the next few days.  The Weather Service has issued a special weather statement advising of the possibility of frost tonight in the Georgia mountains tonight, and a better possibility of frost all the way south to a La Grange – Thomaston  – Warrenton line on Monday night.

The cold blast is bringing a freeze to Southern Ohio, West Virginia, and parts of Virginia tonight, and slightly further south Monday night.  If the cold weather doesn’t get here Monday night, there’s a chance coming again next week, so it’s probably a good time to get the house plants inside.

Today is the first day of Autumn, but you wouldn’t know it by looking at the temperature. An upper level ridge in the northeast will bring ten degree above normal temperatures to most of the eastern half of the US through the end of the month. This, combined with high dew points in the upper 60s to low 70s makes the weather in Georgia more like August, rather than late September.

After much anticipation, the tropical disturbance that caused concern for the Gulf Coast last week turned out to be no big deal. Tropical Depression Ten lasted less than a day, and never developed winds greater than 35 MPH. It is, however, bringing rain to some areas in the southeast that need it, however not North Georgia.

In the Atlantic, Subtropical Storm Jerry has developed in the Atlantic, but isn’t going to affect the United States. Forecasters are watching several other developing systems, including this one:

This low pressure area could develop into a tropical system affecting the gulf. Another low pressure system to the east of the Windward Islands could also become better organized in the next few days, and develop into a storm.

The map above, by the way was created by an updated version of the application I’m using to create the images and other information in the Tropical Center. It’s in final testing, and should go live within the next few days.

Weather forecasters are keeping an eye on an upper-level low pressure system off of the eastern Florida coast that has the possibility of developing into a tropical storm, or worse, by this weekend.

The system has brought rain and high winds to coastal areas between Miami and Savannah this week, and the expectation is that the storm will move west across Florida, and into the Gulf, where it will strengthen into a tropical storm. The picture below shows model predictions as of this afternoon:

While most of the models show the storm passing over the Tampa area, the Canadian model (in yellow) has the storm passing over Jacksonville and into Georgia and Alabama, and the CLP5 model has the storm moving up the Atlantic coast, never reaching the US coastline. Yesterday, the Atlanta Weather Service office noted the possibility of the storm bringing rain to the Atlanta area by the weekend, however, the current thinking seems to be that the storm will stay to our south.

There are still a lot of variables, and a tropical storm may never develop, but it’s worth keeping an eye on.

As of 11 this morning, the National Hurricane Center has recognized two tropical systems, one in the Atlantic, and the other in the Gulf of Mexico, near Texas. Tropical Depression Eight, which will become Ingrid, is located about 1100 miles east of the Lesser Antilles, and is moving along a similar track as did Dean and Felix. The difference, though, is that it appears that Eight’s path will take it north of Puerto Rico and Cuba, therefore making it a greater threat for landfall in the United States. There is still a long way to go with this storm however, as it won’t be approaching any land until sometime next week.

Tropical Depression Nine, which will likely become Humberto later today, is a different story. This storm has been sitting in the western Gulf of Mexico for the last few days, and is finally gaining some strength. The storm is located 85 miles southwest of Galveston, Texas, and tropical storm warnings have been issued from Port O’Connor, Texas to Louisiana.

The map at right shows some of the forecast models for the storm, which is expected to make landfall overnight tonight, and dissipate somewhere near the Louisiana – Mississippi border early Friday morning. This storm is going to interact with a cold front that is expected to pass through the Atlanta area on Friday. The exact location where these systems interact is still in doubt, but this one could be a rainmaker for parts of the southeast United States.

Early September marks the halfway point of the 2007 tropical season, and things are certainly busy, with more on the way. So far this year, we’ve had six named storms in the Atlantic basin, which is well above average. Especially notable is that there have been two category five systems, Dean and Felix, both striking the Mexican/South American coast.

The picture below was taken about 8 AM, and shows Felix striking the South American coast near the Nicaragua Honduras border:

Also today, Hurricane Henriette is making landfall on the other side of Mexico, and is forecast to head towards New Mexico and Arizona, bringing heavy rainfall to that area.

Of more concern to those of us on the Eastern seaboard is a tropical disturbance located off of the Georgia coast. This low pressure system has been milling around since last week, and has the potential to develop into a tropical storm that could bring rain to the Mid-Atlantic and New England states. The picture below shows what several models were predicting what the storm’s path could be:

Both this system and Hurricane Felix are affecting the weather in Georgia, as we are now centered between the two storms’ low pressure. This is bringing us the nice weather we have seen over the past few days. Depending on what happens with these storms, we are likely to continue to see dry weather, even if the system off the coast becomes better organized.

So what to expect as the tropical season goes on? Dr. Gray and his team have issued an updated hurricane forecast (PDF) for the rest of the season and there doesn’t seem to be any significant changes from what was earlier predicted. The team continues to predict 15 named storms, including Felix, but has dropped the number of hurricanes predicted from eight to seven. They are still predicting four intense hurricanes — we are now halfway there with Dean and Felix.

The forecast notes that through August 31st, observed tropical activity accounts for 40% of what would be seen during an average hurricane season. In a normal year, only 33% of tropical activity would be recorded during August.

Hurricane Dean, still a category four storm, is just south of Jamaica this evening. The satellite picture below was taken about 6:15 PM on Sunday, and shows the eye just below the island.

The storm is expected to intensify to category five as it heads almost due west, and will next travel over Yucatan sometime on Tuesday. The following day, it lands on the coast of Mexico, and will still be a tropical storm a day later as it will be inland.

Dean might be one of the most powerful storms measured since storm naming begun. Th tropical season is in full swing now, and it’s quite possible that a future storm Felix is brewing out in the Atlantic, and we might be paying attention to it by next weekend.

Meanwhile, something needs to be done to break the heat and drought in the southeast. Atlanta has already broken the record for number of 100 degree or more temperatures in a summer, and we could have more days with highs past the century mark this week. While the remnants of Erin earlier this week are bringing welcome rain to much of the nation, Georgia is staying stubbornly dry. Based on the current long range outlook, it could stay warm and dry until the end of the month.

Hurricane Dean has been intensifying over the past few days, and is now a Category 3 storm, with winds of 125 MPH, and a very distinct eye. By Sunday afternoon, he should be directly over the island of Jamaica, and just approaching being a Category 5 storm. A hurricane watch is out for the island.

The map above shows the a number of forecast tracks for where Dean will go after passing south of Cuba. While the consensus forecast is to keep the storm on a westerly track, notice the forecast of the GFDL model, which moves the storm northwest, and towards Louisiana. While this forecast is an outlier, the GFDL model has a tendency to be accurate, and the National Hurricane Center has noted this in its discussion, which assumes that the high pressure ridge over the southeastern US will keep Dean to the south. It will be early next week before the situation becomes clearer, but it appears this storm will be one to keep an eye on.

Meanwhile, here in Atlanta, my front yard looks like it’s the first week of October, rather than the third week of August. The almost complete lack of rainfall since the first of the month has brought the effects of the drought back with full intensity, and the dogwood and tulip trees are showing the strain by dropping their leaves.

While there are some storms in the area this evening, August has rapidly taken away any improvement we saw in our cooler, wetter July. The good news is that from this time next week through the end of the month, there’s a better than normal chance of rainfall, and this trend has been holding for the last two or three outlooks.

Meanwhile, the National Climate Data Center issued its temperature and precipitation summary for July. Georgia ended up with cooler than normal temperatures (30th coldest of 113 years), and near normal precipitation (45th driest out of 113 years). Montana, Idaho, and Wyoming had their warmest months ever, while Texas and Louisiana had their third wettest July ever.