You know that it’s been an unusual January when Atlanta records more snowfall than New York City. With no snow forecast for the last day of the month in either  city, Atlanta has recorded 1.4 inches of snow for the month, with most of that coming on the 19th. On the other hand, New York City recorded a trace of snow on the 27th, its only white stuff for the month.

According to an article in the New York Sun,  it’s the first time in 75 years that no measurable snow has fallen in NYC in January.  The article also quotes Weather Service officials as saying that the lack of snow in the Big Apple is due more to storm patterns tracking inland than due to global warming.

Hat tip to the Drudge Report for noticing this.

Wednesday night’s threatened winter storm didn’t end up causing too much difficulty for the metro Atlanta area. The onset of snow between 5 and 5:30 PM managed to put about a quarter inch of the white stuff on my yard and caused the temperature to drop below freezing, but by 7:30 PM, temperatures rose above 32 degrees, and stayed constant or warmed up as the overnight hours passed.

Nonetheless, at least some freezing rain was noticed in parts of Gwinnett, even if it was in limited areas. I noticed that ice was still sticking to trees after noon today along Wisteria Drive in Snellville, and the pine trees along Ronald Reagan Parkway were similarly burdened. So much of what happens in a winter storm is temperature dependent, so just a variation of a degree or so can make a big difference.

The continually varying weather we’ve seen this winter has brought relatively normal precipitation to drought-starved North Georgia. December ended up with more than the normal amount of rainfall, and the official rain gauge in Atlanta is close to what we would expect so far in a normal January.

The latest drought outlook, released today and shown at right, calls for improving conditions for much of the northern part of the state including Atlanta, with at least some relief for the rest of the state. We should see another chance of rain and/or snow Friday night and Saturday morning, with more precipitation for the latter part of next week.  Both the 6-10 and 8-14 long range outlooks call a better than average chance of rainfall.

We’re not out of the drought yet.  But, with drier than normal conditions predicted for the winter due to the presence of La Nina, it can’t be a bad thing that precipitation is running close to normal.

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.

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For fans of changing weather, January so far has been right on target. After starting the year with temperatures well below normal, last week brought high temperatures 15 to 20 degrees above normal.   This week, the pattern will change again, and  bring the possibility of some  sort of frozen precipitation to  North Georgia.

A cold front will move through Georgia today, although it won’t bring any sort of precipitation. After the front passes, look for skies to clear, and temperatures to return to normal or slightly cooler than normal.

Things begin to get interesting on Wednesday, as a low pressure system develops in the Gulf of Mexico, and moves northeast into Georgia, bringing gulf moisture and a chance of precipitation by Wednesday night.  Meanwhile, high pressure out of Canada will force the jet stream southward, bring colder air to the region.  Exactly where these two systems meet will determine what type of precipitation we get.

Right now, forecasters are calling for half an inch of precipitation from the system, with lows Wednesday night just below freezing.  If the storm sticks around long enough, lows will be in the upper 20s Thursday night after daytime temperatures only in the 40s.  It’s possible we could get snow, freezing rain, or sleet, and south of Interstate 20, it will probably be all rain.

The forecast is still long range with plenty of possible outcomes, so I wouldn’t go and get the  sleds out yet.  But, it’s worth keeping an eye on.

This morning’s low temperature of 16.5 degrees in Lawrenceville, Georgia was the coldest I’ve recorded since January 24th, 2005, when the thermometer dropped to 14.6. It’s not a record for the day - that honor is held by 1928, where the temperature dropped to nine degrees in Atlanta.

The coldest weather of the 2007-2008 winter season spread throughout Georgia and Florida, with temperatures (as of 7 AM) including:

Albany, GA - 22
Athens, GA - 17
Atlanta, GA - 15
Brunswick, GA - 27
Destin, FL - 26
Gainesville, FL - 22
Macon, GA - 20
Naples, FL - 34
Orlando, FL - 31
Pensacola, FL - 23
Savannah, GA - 25
Tampa, FL - 29
Valdosta, GA - 24

Yesterday, the temperature topped out at 31.2 degrees here in Lawrenceville, and 30 in Atlanta, which is about 22 degrees below normal. As best I can tell, the last time the high temperature didn’t break the freezing mark was on January 29th, 2005, when we had a high temperature of 31.3. Wind chill readings yesterday didn’t help either, with readings in the single digits.

This week’s weather may turn out to be the coldest of the year. Temperatures will begin to moderate today, and we could see highs around 40 today, near 50 on Friday and in the 60s for the weekend, and into next week. Look for another cold night tonight though, with lows around 20.