The effect of the weather on voter turnout is an oft debated question.  Certainly, it makes sense that more people will be likely to vote on a sunny, warm day than one that is cold and raining.  Unfortunately, at least here in Georgia, it looks like the weather won’t be ideal for voting, and other parts of the country could see rain and snow as well:

As you can see from the image above, which shows expected weather conditions from 7AM through 7PM on Tuesday, there’s a reasonable chance for some light rain while the polls are open. The weather pattern sets up like this: There is a low pressure system that tonight is bringing thunderstorms to Arkansas. Cut off from the main jet stream, the low will migrate south over the weekend, until it reaches the Florida Panhandle. Then, it moves northeast into Georgia.

Meanwhile, high pressure moves down from New England, setting the stage for cold air damming, or the wedge. This weather phenomenon occurs when colder, high pressure air is trapped against the Appalachian mountains as the lower pressure, lighter air moves on top of it. It generally means cool weather with lots of clouds and drizzle. Right now, a high of 66 is predicted for Atlanta, but that could go down depending on the strength of the wedge.

Bad weather is also likely to affect the battleground states of Montana, Missouri and Arizona. It might also affect some of the leaning states such as Colorado, where snow is expected in the mountains, with rain in the plain from Denver east. However, Ohio and Florida–the key states in the previous two elections–are now forecast to have good weather on Election Day.

How all this will affect the election results remains to be seen. Unlike previous years, many people have taken advantage of early voting and don’t have to worry about election day weather. But, if it does rain on Tuesday, keep in mind what my mother always used to say when it rained–unless you’re the wicked witch of the west you won’t melt. Bring an umbrella and vote.

If you have looked at the morning weather forecasts over the past few days, you might have noticed that high temperatures did not reach what was predicted. Despite forecasts for the mid 70s today, the high in Lawrenceville didn’t make it above 68. On Tuesday, the high was 75 in Lawrenceville, and 80 in Atlanta.

Blame the whole thing on cold air damming, popularly known as the wedge effect, where high pressure at the surface is trapped by the mountains and is overrun by lower pressure. We’ve got a high located near the Georgia/North Carolina border that is interacting with lower pressure arriving from the west. Since air at high pressure is heavier than air at low pressure, the lower pressure air forms a ‘blanket’ over the high pressure, causing cloudiness, lower temperatures, and winds from the east.

Tuesday, the damming effect wasn’t as pronounced, and ended just west of Gwinnett, so Atlanta wasn’t affected, and got warmer than it did further east. As the high moved further south, it got stronger, affecting a wider area today.

Meanwhile, we’ve got a summer report card. For the months of June – August, which in weather terms is the summer, temperatures were above average for the United States–the 22nd warmest year out of 114 years recorded, and also much wetter than usual–the 15th wettest out of 114 years.

States with extremely warm summers include California, New Jersey, Connecticut and Rhode Island. Georgia’s summer temperatures were also warmer than normal, ranking 31st warmest out of 114. However, much of the warmth was along the coast and the South Carolina border. The Atlanta area was closer to normal.

Tropical weather contributed to the wetter than normal summer. Mississippi, which felt the brunt of both Fay and Hanna had its wettest August ever. Florida and Alabama, both affected by Fay, had their second wettest August on record. Georgia had its 5th wettest August ever, and was near normal for the summer, again mostly due to the effects of Tropical Storm Fay.

Well, it looks like those predictions for all that rain this week didn’t exactly come true. Despite predictions of one to two inches made as late as Monday, most of the Atlanta area received less than an inch of rain from the storm.

The official rain gauge in Atlanta recorded .53 inches of precipitation as of 8 this morning. Other locations include Chamblee with .28 inches, Marietta with .24 inches, Macon with .69 inches and Athens with .35 inches. Isolated areas got soaked, though. Brunswick reported 1.6 inches, Cordele had an inch and a half, Plains had 2.37 inches and it looks like West Point got the day’s highest rainfall, with 2.97 inches. However, a few miles away in Columbus, then had .7 inches, so the possibility of ‘isolated heavy rainfall’ did come true in a few locations.

I guess you could say that in the battle of pressures, the high pressure won out. The dry air and the very nice weather we had over the weekend had to be forced out in order to get the moist rain producing tropical air into the northern half of the state. As late as 4 PM, the dew point hadn’t gone above 60, and we had a case of cold air damming–unusual in the summer–where the high pressure was being forced up against the mountains, giving the low pressure nowhere to go.

All of this could result in another typical winter phenomenon, a Nor’Easter running up the Atlantic coast, bringing heavy precipitation to the mid-Atlantic and New England. The low will seek its escape out into the Atlantic and keep moving north, bringing unneeded rain to the northeast. Between the CAD (which because it was summer, wasn’t really that cold) and the Nor’Easter, this storm was more typical of what you would see in the winter, instead of the middle of August.

Of course, Fall is rapidly approaching. We’ve finally started lowering both the daily average high and low temperatures, and we’ve lost almost an hour of daylight since the beginning of summer two months ago. Due to the drought the leaves on my trees are dropping, making it look more like mid-October than mid-August, but that’s not due to the cooler weather.

The best hope for drought relief remains tropical weather, and it looks like we may see some activity beginnining this weekend. A tropical wave east of Cuba is drawing attention, and could develop into a tropical storm by the weekend. Some models have it crossing Florida into the gulf, while others keep it along the Atlantic. The northeast quadrant of a storm is the one that tends to get the most rain, so for really beneficial rainfall in north Georgia, we really need to see something come from the gulf, rather than from the Atlantic. If this wave doesn’t do the trick, however, there will likely be others behind it.

If you are like me, you were probably looking forward to the predicted sunny skies this afternoon, which obviously didn’t happen. The moist air left over from Saturday’s rain remained in place as the slow moving cold front that brought the rain stalled across south Georgia. This kept the clouds in place and kept the temperatures cooler than expected.

If you were hoping for bright April skies this week, it looks like that won’t happen either, and there is a possibility of rain affecting the upcoming Masters Tournament in Augusta this weekend. For the first part of the week, we’ll see another wedge keep temperatures cooler than normal, with a good chance of fog and drizzle in northeast Georgia.

The wedge moves out on Wednesday, leaving us with a pleasant day for the first round of the Masters on Thursday, but setting us up for a chance of showers and thunderstorms through the weekend. Right now, it looks like the greatest chance of rain is in the western part of the state, but golfers could see rain on Friday and Saturday. The storm system moves out Saturday night, leaving better weather for Sunday.

The week of the 13th promises to be interesting, at least by the early forecasts. There’s a good possibility that cold Canadian air will make one last stand, with a chance of a very late freeze for the first part of the week. Both the 6-10 and 8-14 day outlooks are calling for colder than normal temperatures, and Accuweather is calling for lows in the mid 30s a week from Monday and Tuesday. If you were planning to get your annuals out this week, it might be a good idea to hold off until the forecast becomes clearer as the week wears on.

I had the opportunity to talk to Georgia Congressman John Linder last week, and I asked him to comment on global warming, and Washington’s efforts to address the problem. Linder, who has published several editorials on the issue, said that Global Warming was not settled science, and pointed out that the poles of Mars, Jupiter and Pluto are all thawing — surely not the result of human activity. He also pointed out that there was less Arctic ice in 1940 than now.

Linder says that the global warming issue is “all about taxes,” and he is worried about the current effort to make polar bears an endangered species, despite the fact that there were 5,000 of the bears back in 1950, and 25,000 now. He fears that the issue may ultimately go before the courts, and we will have judges deciding global warming policies that could affect businesses across the country.

It looks like things could get fairly nasty Wednesday Night and into Thursday for much of the Atlanta area north of Interstate 20, and especially for the northeast counties, including Gwinnett.  An incoming low pressure system in the Gulf of Mexico will bring precipitation to Georgia beginning Wednesday morning.  Meanwhile, the high currently over the eastern part of Kentucky will move northeast, running into the Appalachians, and causing a ‘wedge’, or cold air damming to affect northeast Georgia.

What happens is that the colder air gets trapped on the western edge of the mountains, and the approaching lower pressure, warmer air slides above the colder, heavier air. You can tell when we’re in a CAD situation when the wind comes from the east, and it doesn’t warm up much during the day.

The presence of warm air above cooler closer to the ground tends to favor the formation of sleet or freezing rain, since the warm air layer will melt any snow as it passes through, while the cold air close to the ground will either re-freeze the precipitation, or cause freezing when the water hits the surface.

In the last day, forecasters have increased the total amount of expected precipitation from the storm to almost an inch, while dropping the low temperature Wednesday night, especially in the northeast counties most affected by the wedge.

Here’s what to expect tomorrow in the Gwinnett area:

7 AM  – The leading edge of the precipitation moves to the Atlanta area, but nothing may hit the ground because the air is so dry.  Look for dew points to increase in the morning, and the temperature to rise above early morning below freezing lows.

11 AM – Light rain begins, with temperatures above freezing, so no problems.

7 PM – After sunset, temperatures begin to cool, and the rain increases in intensity.  We may see a little sleet in the early evening.

11 PM – Temperatures drop below freezing.  Continued rain and sleet, with some freezing rain.

4 AM – The intensity of the rain begins to slow, but because temperatures have been below freezing, we’re probably seeing freezing rain at this point.

11 AM – Temperatures rise above freezing, as most of the rain  has passed from the area.

Of course, this is just my best guess, and things could  change. The further south and west you are, the better the chances that this is just a rain event. In any case, Thursday morning could be nasty.

Depending on where you were, you may have been disappointed with the Thanksgiving Day rainfall totals. Here in Lawrenceville, I recorded .15 inches for the storm, which is less than many other areas did. Looking at the radar as the storm passed over the Atlanta metro area, most of the rainfall seemed to be to the north of Georgia 316, and that’s borne out by some of the precipitation reports:

Athens: 1.17 inches (they really needed it)
Gainesville: .46 inches
Johns Creek: .93 inches
Alpharetta: 1.09 inches
Rome: .87 inches
Atlanta: .16 inches

The good news is that we’re due for some more rain before the month ends, and then at the beginning of December. Cooler air is beginning to filter into the state from northwest to southeast, and Friday should be a sunny, if cool, day for shopping or golf. (Someone told me that the day after Thanksgiving is one of the biggest days for golf – the ladies go shopping and the men to golfing.)

By Saturday, a warm front begins to approach from the south, bringing a return of moisture to North Georgia, and an episode of cold air damming, or ‘the wedge’, where the warmer air sits on top of the colder air already present. This is likely to lead to showers Saturday night into Sunday, and then another front approaches from the northwest, bringing a chance of rain on Monday or Tuesday. At this point, it looks like the two systems could bring an inch and a half to two inches of rainfall by Tuesday evening, with the bulk of the rain on Monday night. You can see the predicted five day rainfall totals in the map on the right.

Things clear out with close to normal temperatures for midweek, and then yet another front approaches for the weekend, with a possibility of rain from Friday through Sunday.

All of this doesn’t mean that we’re out of the drought by a long shot. But, even if you didn’t get the rain today that you wanted, there’s more coming.

With the Dog Days of summer ready to begin tomorrow, it’s time to take a look at what we had in June, and what to look forward to as the hottest part of the summer begins.

June actually ended up having close to normal rainfall in Georgia, largely because of the effects of Tropical Storm Barry in the southeastern part of the state. Up here in North Georgia, Atlanta was just about at normal June rainfall with 3.66 inches of rain. With 4.7 inches, Columbus had more than an inch of above-normal rain. Macon saw 4.69 inches of rain, or 1.15 inches more than normal. Athens continued its deficit, with 2.17 inches, or 1.77 inches below normal. And finally here in South Gwinnett, my rain gauge recorded 5.03 inches, including over two inches from the thunderstorms that rolled through on June 28th.

The map above shows total estimated rainfall for Georgia in June. Areas in green and yellow, including most of the northwest part of the state, were short of rain.

The month ended up being warmer than normal for most of the state Mean temperatures include Atlanta at 79.5 degrees, 2.7 degrees above normal; Gainesville at 77.9 degrees, or 3.3 degrees above normal, and Athens at 78.5, 2.2 degrees above normal. Here in Lawrenceville, I was at the low end of the scale, at 76.5 degrees mean for the month. Part of the reason for that may be that I had more rain than normal, which tends to keep things a bit cooler.

July is likely to be warmer than normal as well, with the Weather Service estimating a 40% chance of above normal temperatures for all but the southernmost portions of Georgia. It may be that most of that heat will be towards the second half of the month, though, with the medium range outlook from the 8th to the 16th calling for normal to below normal temperatures.

On the rainfall side, the Weather Service doesn’t make a firm call one way or another, however it looks like we’re likely to see continued wet weather in the short term, or until the massive storm that is flooding much of Texas and Oklahoma finally goes away.

Today was the first time since July 10th, 2005 that a day in July didn’t go above 80 degrees (at least in my records). While the clouds kept the temperatures down, the main reason for the cooler weather is a phenomenon we normally see in the wintertime: cold air damming, otherwise known as the wedge. High pressure air in the mid-Atlantic states flows down the side of the Appalachian mountains, while low pressure air moves in from the southwest. Because high pressure air is heavier than low pressure, it becomes trapped underneath the low pressure system, and keeps the temperatures down (and the humidity up).

The good news is that the drier air will be moving in over the next few days, and we will, with any luck, have very nice, cooler than normal weather for Independence Day.

There’s a reasonable chance that metro Atlanta might get its first wintry weather Wednesday night and into Thursday, but the forecast is tricky, and a lot of what will happen will depend on exactly how conditions set up.

During the day Wednesday, North Georgia will be under control of a high pressure system located over Virginia. This will make for a chilly day again. Meanwhile, a low pressure system is moving east. It’s the same one that has brought freezing rain to Texas earlier this week. Whether we get a major winter event depends on how these two systems interact.

As the warm, moist air moves into Georgia, it will meet the colder air. Since the colder air is heavier than the warmer air, it will remain below the warm air. This effect is called Cold Air Damming, or popularly, ‘the wedge’. The possible effect is that instead of temperatures rising with the incoming rainfall, it will remain cold enough at the surface to cause sleet or freezing rain.

Below is the Weather Service graphical forecast for 7 AM on Thursday:

You can see that below Macon, there will be heavier precipitation, and it will be all rainfall. There’s an area north of that that may see heavier icing, since it will be in the more active part of the rainy sector, while also under the influence of the wedge. North of a line from Columbus to Athens, including Gwinnett County, freezing rain is also predicted.

So what happens on Thursday morning is a function of how strong a wedge develops, and how fast the precipitation moves. Since the ground is warm because of the springlike weather we saw before today, there isn’t likely to be any accumulation on the ground. However, if we do get freezing rain, it will affect trees and power lines, and things could turn nasty. If it’s too cold, we get sleet, which won’t be a problem. And, if the wedge is weak, we may get all rain as temperatures close to the surface remain above 32 degrees.

Stay tuned…

If you look at the forecast highs for Sunday, North Georgia is only expected to reach 60 degrees, while surrounding areas, including Tennessee, Alabama, and South Carolina will be close to 70. In fact, you would have to travel north to Boston, or northwest to the Great Plains to see similar low temperatures. The reason for the anomaly is the buildup of a classing wedging situation.

For the last few days, our weather has been dominated by a high pressure system centered over Eastern Canada. This has brought dry air down the East Coast. The low dewpoints allow the air to cool at night (last night’s low of 45 degrees, for example), but still warm up during the day.

On Saturday evening and Sunday, a low pressure system will approach from the west, bringing higher dewpoints, warmer air, and a chance of rain. Because the high is still bringing in dry air, and because the dry air is heavier than the more humid air, it will get trapped underneath the warm front.

The net effect will be to provide a cloudy day, where the temperatures never get a chance to recover from the cool nighttime temperatures. If there’s a positive side, the wedge will also prevent the worst of the rain, which could reach an inch or more to our west from getting into Georgia, particularly East and Central Georgia.

So, here’s my prediction for Sunday: If you see the temperatures rising much above 60, then expect some rain. The warm front will have won out over the wedge. On the other hand, if it stays cool, the rain will be minimal: less than a tenth of an inch.

Forecasters have been predicting a major rain event that could bring up to 3 inches of badly-needed rain to Atlanta. The Weather Service has issued a flood watch. Radar and satellite views over the last 24 hours show approaching rain, but it never seems to make it to Atlanta.

The storm’s slower than expected advance has been stalled by high pressure to our north. Heavy cool, dry air in north Georgia produced a wedge situation, forcing the lighter warm moist air upward, and wringing the moisture out. The wedge is part of the reason why Gwinnett didn’t record any rain yesterday, while down in Hampton, the Golden Corral 500 was rained out. They have rescheduled it for today, but I don’t think they will get it in.

The HPC is predicting that we could get up to two inches of rain from the storm, with most if it coming after sunset tonight. It should start to clear out by Tuesday midday, and high pressure will follow, bringing fair weather for the remainder of the week.

Today is the first day of spring, but the warm weather we saw last week may stay away through the end of the month. long-range forecasts say we should expect lower than normal temperatures and below normal precipitation through April 2nd. One forecast I saw predicted highs in the 50s to low 60s, and no high temperature above 70 degrees until the first of the month, when our normal daytime high should be in the upper 60s.