The relatively dry weather over the past two weeks got me itching to turn on the sprinkler system and water the lawn. Keeping in mind the gardening advice that lawns should receive an inch of water a week, it would seem to make sense to water, since we haven’t had a one week period with an inch of rain since March.

I decided to use a soil moisture tester I have before watering. It showed that 3 or 4 inches below the surface, there was actually plenty of moisture — and no need to water.

We have abundant soil moisture, despite the lack of recent rain, for several reasons: First, we had plenty of rain during the last week of March, and much of that rain is still in the ground. Trees draw plenty of water from the ground once they are fully leafed out, but not as much when they are bare. Finally, our cooler than normal temperatures have kept soil temperatures around 60 degrees, by my records, about 6 degrees cooler than what it’s been on May 7th over the last few years. The cooler temperatures also tend to keep moisture in the soil.

Last week’s cooler than normal temperatures are going to be replaced by normal to slightly warmer than normal weather during the upcoming week. The first week of May saw average temperatures about 7 degrees cooler than normal, accented by lows in the 40s. Lows this week will be about 15 degrees warmer than last.

High pressure to our east will bring winds from the southwest, bringing in more humidity as well, adding to the impression that things are much warmer than they have been so far this season. This high pressure will also keep the effects of a low over the upper Midwest away from Georgia, at least through Monday. Midweek, things are a bit more unsettled, as there is a chance of rain Tuesday and Wednesday, and again towards the weekend. For the week of the 15th, we’re likely to see temperatures returning to a more normal range, with highs in the upper 70s, and about a normal chance of precipitation.

If temperatures warm as expected next week, and if we are able to avoid rain, it might be time to water by next weekend, but I’ll use my moisture tester to make sure.

The predicted change in the weather pattern at the end of this week may turn into some of the coldest weather of the season. Most forecasts for periods more than a day or two out are based on computer models, and one such model, the Global Forecast System, or GFS, was predicting highs in the 20s next Saturday or Sunday. The National Weather Service forecaster commenting on this possibility urged readers to remember that it was likely to change.

The map to the right represents the predicted low temperatures in the eastern half of the country for the period between January 16th and January 22nd. As you can see, the low during that period could be around 15 degrees, a temperature even colder than the frigid blast we had just before Christmas.

All the cold weather will be caused by polar air pushing southward starting around the middle of the week. We’ll begin to see the effects of that on Thursday, as some of the rain plaguing the Ohio valley moves into North Georgia. As the rain moves through, the temperatures drop, leading to highs Saturday only in the mid 40s. Longer-range, we might see some wintry precipitation the week of the 17th.

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