We are now just one week away from the start of winter. You may think winter begins on December 20th, the shortest day of the year, but from a weather perspective, winter is the three month period of December, January and February. We’ve enjoyed a relatively mild (albeit wet) fall, with temperatures yet to drop below freezing in the metro Atlanta area, but that will change soon.

The latest predictions from the weather service for winter are pretty much in line with earlier forecasts. Much of the South and Mid-Atlantic states have a 40% chance of colder than normal weather, while the upper Midwest and northern states should be warmer than normal. This is a typical winter pattern in El Nino years like we have this year.

The precipitation forecast also reflects typical El Nino conditions, with wetter than normal conditions stretching from California along the southern US border to South Carolina, and drier than normal conditions centered over Tennessee and Kentucky. This puts Georgia right in the middle, with the north likely dry, normal in the middle, and wet in the south. Exactly where the dry/wet lines fall could make a big difference in how the weather plays out.

The extended outlook for the first week of December, if it plays out, will give Georgia its first really cold weather of the season. The graphic to the right shows the temperature outlook for November 29th through December 3rd, with an extremely high chance of colder than normal weather. The 8-14 day outlook is similar, although cold is not quite as likely. The entire country from the Rocky Mountains east is going to be in a cold spell.

The extended outlook also shows a higher than normal chance of precipitation for the Southeast. Could this mean we have a shot at snow or freezing rain? While the weather service doesn’t get specific more than seven days out, Accuweather.com is predicting a chance of freezing rain the night of December 1st, with low temperatures in the upper 20s much of next week. Weather.com predicts warmer overnight temperatures not dropping below freezing, with showers.

Keep an eye on the forecast: we’ll have a better idea by the weekend on what’s in store for next week.

The winter weather forecasts for 2009-2010 have arrived, and there appears to be a lot of agreement between the three I have reviewed so far. This winter (December through February) is likely to be affected by an El Nino episode that alters the jetstream patterns, especially the southern branch, bringing a colder, wetter winter for most of the southeast and mid-Atlantic States.

The Weather Service predicts a better than 40% chance of cooler than normal weather in Virginia, North Carolina and Georgia, and the southern half of Alabama, Mississippi and Louisiana. Kentucky, Tennessee, and the northern half of the deep South are also likely to be cooler than normal. Much warmer than normal conditions are expected in the northern Great Plains and Rocky Mountain states, with warmer than normal conditions in Wisconsin, and stretching south into Nebraska and New Mexico.

The Accuweather winter forecast restricts the much below normal temperatures to Tennessee, Alabama and Mississippi, along with northern Georgia, western Virginia, and the western Carolinas. They predict above or below normal temperatures for the entire country, with no area set for normal temperatures.

The Weather Service precipitation outlook calls for a much greater chance of rain in Florida south of Orlando and in south Texas, with above normal precipitation in southern Georgia, most of Texas, and in California. Drier than normal weather is expected in the mid-Mississippi valley and in the northwest. The rest of the country has equal chances of above or below normal precipitation.

The Accuweather forecast brings the above-normal precipitation chances further north, covering the Carolinas, Georgia, Alabama, Mississippi, and west to New Mexico, and north into California. Dry conditions are expected in the midwest and upper Northwest.

All of this means that the metro Atlanta area has a better than normal chance of seeing snow or ice this winter, especially when compared to the last few years. And that is what WSB Radio meteorologist Kirk Melhuish says in his preliminary winter outlook. Melhuish predicts normal temperatures and above normal precipitation in the Atlanta area, with an above normal chance of ice and snow. He will issue a final outlook around Thanksgiving.

Our friends at the Climate Prediction Center have finally released their 2008/2009 winter outlook, which calls for warmer then normal temperatures for much of the Mississippi Valley states, and drier than normal weather for most of the southeast and Gulf Coast. Here’s the temperature outlook:

And here’s the outlook for precipitation:

The CPC admits that without strong signals for either an El Nino or a La Nina winter, it presents a challenge to create its outlook, and admit that there could be a lot of variability in the weather this winter:

“These patterns are only predictable a week or two in advance and could persist for weeks at a time,” said Michael Halpert, deputy director, Climate Prediction Center. “Therefore, we expect variability, or substantial changes in temperature and precipitation across much of the country.”

if the outlook holds true, Georgia will experience a warmer than normal winter in the northwest part of the state, extending through the Atlanta metro, with less than normal precipitation, especially in the southern part of the state. The winter outlook is based on the CPC’s normal 3 month outlook for December, January and February which was released on Thursday, and pretty much follows the ideas they have had for the past few months.

I don’t know how much faith I have in their outlook, though. So far in November, Atlanta is running about 2.6 degrees cooler than normal, and I don’t see that trend changing through December. (The rainfall deficit seems to match the weather service’s ideas, though.) So if December is cooler than normal, we’re going to need a warm January and February to make up for it.

Updated winter forecasts from Accuweather and others will be available soon, and I’ll keep you posted.

With winter just a month away from a meteorological perspective, it’s time to take a look at some of the forecasts that have been issued for a glimpse of what the season will bring.

We’ll start with the always interesting and sometimes reliable Old Farmer’s Almanac’s prediction for the southeast, which includes much of North Carolina, South Carolina and Georgia. Overall, they expect cold temperatures and normal to above normal precipitation, with more precipitation in the south. Look for above average snowfall, and the coldest weather in mid to late December, mid-January and mid-February.

On the other hand, Accuweather’s Joe Bastardi says to expect colder than normal weather for much of the east, with December being the coldest month relative to normal, a January thaw, and then cold again in February. The East can also expect more snow than last year.

WSB Radio forecaster Kirk Melhuish released his preliminary winter outlook this week, and it is similar to Accuweather, with ‘bookends’ cold spells at the beginning and end of the season, and less snowfall and slightly less rainfall than average. Kirk will issue his final winter forecast at the beginning of December.

Finally, what does the Weather Service say? They haven’t done a press release on their outlook as they have done in past years, so all you can do is look at their 3 month outlook for December-January. Unlike the other forecasts, the Climate Prediction Center thinks we have a better chance than normal for warmer weather. They also predict a 33% chance of drier weather, especially in mid and south Georgia.

Georgia certainly got a taste of early cold weather this week, with temperatures about 20 degrees below normal. While it appears that most of the Atlanta area core counties managed to escape a freeze, outlying counties, including Carrollton, Dallas, Athens, Cartersville and Peachtree City all dropped below the freezing mark. Even Macon recorded a low of 32 this morning. Today was the worst of it, though, and morning temperatures should be warmer as the week wears on. The next chance for freezing weather may not be until the 9th of November, closer to the normal first freeze date.

Meanwhile, New England is digging out of its first major storm of the season. Snow totals include 17 inches in Star Lake, NY, 12 inches in Saranac Lake, NY and 10 inches in Hazleton, PA. Normally, that area doesn’t get an inch of snow prior to November 15 north, and December 1 south, so this snow was definitely early.

There’s actually a relationship between the cold weather in Atlanta and the snow in the northeast. The deep upper low that brought the bad weather to New England acted as a roadblock to the cold, high pressure air from Canada, forcing it south instead of east. Now that the low is finally moving out to sea, the cold air can move north again as a more normal west to east flow takes over down here.

Reader Morgan wanted to know if we were likely to see some relief from the drought and any changes to the climate patterns we’ve been seeing over the past few years.  While I wish I was as prescient as he makes me appear, let’s take a look at what might happen this winter.

We’ll start with the three month outlooks from the Climate Prediction Center. The three month outlook from October through December calls for equal chances of above or below normal temperatures and precipitation for the period east of the Mississippi River.  Note this doesn’t mean a ‘normal’ fall season–it’s more like the indicators they are using for the outlook don’t point strongly one way or another.

For the winter proper, from December, 2008 through February 2009, the CPC says we’re likely to see warmer than normal temperatures for most of the US, and drier than normal conditions in the southeast, including Georgia. Based on what I’ve seen in the past, this prediction is likely to become the ‘official’ winter outlook that the Weather Service will release in Mid October.  You’ve got to take these outlooks with a grain of salt.  In their Winter 2007-08 outlook, they predicted a warm and dry seaon, while in actuality, the results show we did have above normal temperatures in Georgia, but we also had above normal rain.

Another way of trying to predict future weather is through the use of analogs.  The theory here is that you look at previous years with similar weather conditions to the current year, and examine what follows.  For the upcoming winter, good analog years would be those that had above-normal Atlantic hurricane seasons coming off an La Nina winter that led to neutral conditions. Kirk Melhuish of WSB Radio is suggesting that we should look at 1976, 1985, 1989, 1996, 2000 and 2005 as analogs. I’ve heard 1985 as a possible analog year from other forecasters as well.

I dont’ have handy access to weather records prior to 1991, which makes it hard to compare 1985, although I found a map of precipitation from October-March that showed drier than normal conditions in North Georgia.  For the years I do have records, in Atlanta the 1996-97 winter had 54% of normal precipitation, for 2000-01, 66% of normal, and only for 2005-06 did we see normal precipitation from December through February, with 102%.

So, based on this evidence, it doesn’t look like we’re going to be seeing a huge change in the drought situation through Spring.  However, the proof of the pudding is in the eating, and ultimately, the weather will tell us what happens.

Side Note:  No rain was reported at Atlanta Hartsfield yesterday or today, so it looks like we’re going to be short on precipitation for Septermber, with .75 inches or 18% of normal.  Some folks got lucky, though.  I was talking to a friend tonight with a reliable rain gauge who told me that he recorded 1.5 inches in about 20 minutes last night during a popup storm at his location between Snellville and Loganville.  “I was so glad to see some rain, I went outside with my hands up,” he said.  “That’s the first rain I’ve seen since Fay came through with four inches last month.”

Today ended up being a big day for releasing weather data and forecasts, so let’s take a look at the news:

First of all, the Weather Service issued its final Winter 2007-08 forecast. Because of the strengthening La Nina in the Pacific, the revised forecast slightly extends the boundaries of the wet/dry warm/cold areas it predicted in it’s preliminary October forecast. If conditions go according to the forecast, it’s going to be wetter than normal in the Pacific Northwest and in the Ohio/Tennessee Valleys, and drier than normal for much of the southern half of the country, including virtually all of Georgia. It’s also going to be warmer than normal for most of the country, except the Pacific Northwest, with the heart of the heat in the Plains States.

The weather service also issued its outlook for December. The temperature forecast looks almost exactly like what they are predicting for December- February:

Meanwhile, for precipitation, the Pacific Northwest is likely to be wet, while the south is likely to be dry:

Also today, the Climate Prediction Center released its drought outlook for the next three months. The big change from the previous outlook, issued two weeks ago, is that much of Texas and New Mexico are expected to see developing drought conditions:

No improvement is expected in the Southeast, however, some relief is forecast in Kentucky and Tennessee, due to the expected precipitation from the La Nina conditions. The outlook for developing drought in Texas shows you that no matter how much rain you get, drought could be just around the corner. Here’s a map of rainfall from January through October, 2007:

While it confirms that North Georgia, eastern Tennesee, and northern Alabama have had the driest months ever, it also shows that portions of Texas that had their wettest ever January through October. Now, that area is expected to go into a drought.

Last night’s rain did little to help the Georgia drought. I recorded about a third of an inch of rain and the gauge over at Atlanta’s Hartsfield Airport recorded a measly .14 inches of precipitation. So far this month, we’ve received only about 6% of what we would expect in the first two weeks of November. It’s probably going to stay dry through Thanksgiving, but the last week of the month could bring some more rain. Computer models have been waffling on exactly what will happen, but both the 6-10 and 8-14 day forecasts are calling for a better chance of rain than normal for much of the eastern half of the country.

I can’t sign off without noting the bankruptcy filing of Pike’s Nurseries here in Atlanta. I’ve probably shopped at Pike’s for 20 years, and have always felt that the quality of their plant material and the helpfulness of their staff made it worth paying a little more that what I could have at a Home Depot, Lowes, or Wal-Mart. I stopped by #6 on Lawrenceville highway today around lunchtime, and it was deserted. Keep in mind that it’s still a good time to plant, and that water demands during the winter aren’t as great as they are during the warmer seasons.

But even if you don’t want to plant anything outside right now, keep in mind that Christmas is right around the corner. They were unloading the first batch of Christmas trees while I was there — think about getting your tree at Pike’s this year — I plan to.

Accuweather.com has released its Winter 2007-2008 forecast, and it calls for much warmer temperatures than normal for most of the country. Long range forecaster Joe Bastardi says that the beginning and end of the season will probably be closest to normal, but the period from mid-December through February could be one of the top ten warmest winter periods, with the bulk of the warmth centered over the Tennessee Valley and the Carolinas.

Bastardi also has a warning for the drought starved southeast:

“We will know in the next three to four weeks whether a storm from the tropics might arrive to help the southeast drought situation. If that doesn’t materialize, those states are looking at a very dry winter, with precipitation amounts less than half of normal in some areas.”

A combination of La Nina conditions and warming Atlantic Ocean temperatures are the chief culprits for the warm weather. East of a line from the Great Lakes to the Southwest could see temperatures above normal 75% of the time.

Update 10/25/07 – here’s a link to a more detailed winter forecast from Accuweather.

The National Weather Service has issued its predictions for the upcoming winter, and for most of the country, the outlook is for warmer than usual temperatures. The persistent drought in the Southeast is also a concern in the press release put out by NOAA. Here’s a look at the predicted temperatures from December, 2007 through February 2008:

While the greatest chances for above normal temperatures are in the southern Plains states, virtually the entire country with the exception of the Northwest is expected to be warmer than normal. Cooler than normal temperatures aren’t predicted for anywhere in the country. Part of this is due to the long-term trend towards warmer temperatures compared to NOAA’s base years of 1970-2000, and the other part is due to the La Nina conditions expected this winter, particularly in the southeast. Even though temperatures are predicted to be warmer than normal, the Weather Services says that on a nationwide basis, they should be cooler than the 2006-07 winter.

As far as the chance of precipitation goes, much of the southeast and southwest is predicted to be drier than normal, while the northwest is going to be wetter than normal, both due to the La Nina conditions. Also predicted to be wetter than normal is much of the Midwest.

The weather service stressed that this outlook isn’t a snowfall forecast for the season, claiming that it’s difficult to predict exact snowfall patterns more than two weeks out, which is true. I’m a bit surprised that NOAA used the long range outlooks they issued back on September 20th as the basis for their winter outlook, when an updated one is due out in a week, and should in theory be more accurate. Perhaps they wanted to be ‘in the lead’, prior to other forecasters making their predictions.

The Weather Service provided further confirmation to what it had been hinting at for the past several months yesterday, when it issued a news release reporting a developing La Nina condition. The expectation is that La Nina conditions will continue to develop over the next three months, and provide a wintertime La Nina weather pattern. This expectation is backed up not only by observation, but by computer modeling.

If La Nina conditions develop, what can we expect for this winter? According to statistics gathered during previous La Nina years, there is a 49% chance of less than normal precipitation in North Georgia from January through March, and a 60% chance that temperatures will be above normal. There’s only an 8 percent chance of below-normal temperatures, but there is still a 32% chance of above normal precipitation.

La Nina conditions occur when sea surface temperatures in the Pacific Ocean are below normal for more than three months in a row. It is the opposite of El Nino conditions, where equatorial ocean temperatures are above normal. The last time we had a La Nina episode was back in 2000.

A trough in the Eastern part of the United States is going to bring us a real taste of winter weather in the first part of the week leading up to Thanksgiving. There is a reasonable chance of snow flurries overnight Sunday into Monday, but don’t panic — there’s no chance of accumulation. By Tuesday night, temperatures will drop to around 30, or even the upper 20s. You can expect gusty winds throughout the period, so all in all, it’s not going to be a great start to the week.

By Wednesday, the low pressure system will move away from us, allowing warmer temperatures back into North Georgia, with highs possibly brushing 70 degrees by the weekend. The long range prediction is for warmer than normal temperatures through the first of December.

November so far has proven to be colder and wetter than normal. Our rainfall of 3.61 inches measured here is about 170% of normal for the month to date, although if we don’t get more rain it will be about normal for the month. It has been cooler than normal — about two degrees below average so far. So, maybe warm weather for the Thanksgiving weekend will even things out a bit.

Kirk Melhuish of WSB radio has released his winter forecast. It largely follows the pattern of the other major forecasters, with a cooler than normal winter, and normal precipitation. Kirk does think that we’ll have a better chance than normal for an ice storm, though.

The National Weather Service also issued its final update to the winter forecast. While the predicted near normal temperatures and normal to slightly more than normal precipitation is unchanged for the Southeast, the meteorologists have changed their prediction for the Southwest from normal to equal chances of above or below normal temperatures.