This weekend’s thunderstorms didn’t bring much drought relief to Gwinnett county, despite the tempting red splotches on the radar all around. Saturday morning brought less than a tenth of an inch at my house, and then nothing for the rest of the weekend.

Other locations did see a reasonable amount of precipitation, though. A storm passing through early Sunday morning and some afternoon rainfall brought .78 inches of rain to Covington–the most rain recorded in North Georgia on Sunday. Meanwhile rainfall amounts varied a lot, even at relatively close distances. Marietta recorded .73 inches on Sunday, while nearby Charlie Brown Airport in Atlanta got not a drop. In Cartersville, they had a quarter of an inch, while Rome received only trace precipitation. Atlanta, which has recorded a scant .23 inches of rain for all of June ended Sunday with only 1/100 of an inch of rain.

The weather over the last week or so has featured an upper level trough over the east coast that has tended to keep tropical air from the Gulf of Mexico away. Thus dew points have been relatively low, making it harder to generate thunderstorms. The rain we’ve had has been caused by small disturbances traveling on the edge of the trough. That is likely to change later in the week, as the trough moves out and moist air returns. However after this evening, we’re not likely to have a good chance for precipitation until the weekend.

Today’s low dew point of 38.6 degrees is the lowest summer reading since June of 2006, when the dew point dropped to 38.4. With a temperature of 82 degrees, the relative humidity at 5:30 PM was an almost desert-like 21%, which is unusual in Georgia during the months of June, July and August.

An upper level low pressure system centered over Quebec is bringing cooler air to the northeast–for example, it’s only 59 in Pittsburgh as I write this, and 63 in Cleveland. In Morgantown, West Virginia it’s 60. The colder Canadian air comes south to the west of the low. While North Georgia isn’t cooling down to that extent (although low 80s are a welcome change from the 90s we saw recently), as the air warms up as it travels further south, it becomes drier, dropping humidities, and therefore the dew point.

The dry air also brings 30 degree temperature swings. This morning’s low was 57, while this afternoon’s high was 86–almost a 30 degree difference. The long summer daylight warms the air, but the lack of water vapor means as the sun goes down, more heat is radiated into the atmosphere. Today’s low dew points mean it’s likely to be even cooler tomorrow morning.

Of course, this can’t last. We’ll have two more nights of open window weather with lows in the 50s, but by Friday, the low moves out, and we’ll be more influenced by gulf moisture from the south. Showers and thunderstorms potentially return by Saturday, and things remain unsettled into the early part of next week.

A few things of interest to the weather community:

The first tropical storm of the season has developed in the Eastern Pacific Basin. Tropical Storm Alma is currently passing over Nicaragua in Central America, and is forecast to dissipate as she heads north towards the Yucatan peninsula. The Atlantic tropical season starts on Sunday.While some runs of the GFS model indicated some sort of storm developing in the Gulf of Mexico this weekend, it appears that it was either a false alarm, or the GFS was really picking up on Alma.

The drought continues to diminish somewhat. Last week, all of metro Atlanta dropped from the extreme drought category to simply severe. As of this week, only Stephens, Franklin, Hart and Elbert counties in northeast Georgia are in extreme drought conditions, and 27% of the state is in a severe drought, including most of the area covered by the level four drought conditions.

Meanwhile, the Georgia EPD further relaxed watering restrictions for golf courses, which previously had only been allowed to water their greens. As of today, the new order from state EPD chief Carol Couch says that fairways and tee boxes can be watered, however golf courses can use only 65% of the water they used in 2005 or 2006.

This is actually a good thing, since golf courses typically get their water from natural lakes or ponds rather than the municipal water systems, and they contribute to the economy both directly and indirectly.

It looks like the hot, humid days of summer may be upon us. Despite today’s cooler than normal weather, caused by cold air damming that kept the clouds around and the temperatures low, the weather service says highs will be in the upper 80s beginning Saturday and continuing all next week. In addition, dewpoints are going to stay in the 60s, meaning you’ll feel the humidity and the heat more than you have since last summer. Accuweather is predicting a high of 93 for Tuesday, which would be the first time this year we’ve broken 90.

It’s been about ten days since I last posted. I guess you can blame the lack of posting on a combination of chamber of commerce weather in the Atlanta area, my trying to get the garden in shape and a busy April that is taking me out of town three times this month.

There really hasn’t been much to complain about the weather since the cold threat back on April 14-15.  Even that turned out to be a bust, with temperatures hovering just above freezing. We seem to have settled into a pattern of beautiful weekday weather, with a cold front coming in on the weekend to bring rain.  It looks like that pattern might continue for another week or two.  Rain is expected both this weekend and next. It’s bad news for the weekend gardener trying to plant annuals in wet soil.

Of course, wet soils are the least of the problems for much of the Midwest and Northeast, which have been inundated with precipitation, leading to flooding.  Missouri had its second wettest March ever.  Cape Girardeau, Missouri had 13.84 inches of rain in 48 hours last month–about what the Atlanta area has seen all year.  Pennsylvania and New York had their third wettest March since recordkeeping began.  Georgia ended up having its 36th driest month, however it appears that for a change, the northern half of the state had closer to normal rainfall than the southern half.

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Some folks in North Georgia got an unusual late March sight: snow flurries fell briefly this afternoon.  Although it was 45 degrees outside, much colder air aloft combined with lower pressure caused by a short wave passing through squeezed out just enough moisture for the flakes, which melted on contact with the ground. Temperatures today are 20 degrees cooler than normal, and the northern two thirds of the state will see a freeze tonight.  If you succumbed to the spring planting urge over the weekend, either bring your plants in, or at least cover them over.

Tonight’s freeze won’t be anywhere near as bad as the Easter Freeze of 2007. though.  Not only is it likely to be a bit warmer than the 28 degrees recorded last April, but not as many plants have started to bloom. A freeze in late March isn’t too unusual.  For metro Atlanta, the typical last frost occurs sometime between April 1st and April 15th.

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