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It's not often you can talk about frost and a possible tropical system at once. The cool air from Canada settling into the region will make it sweater-weather for most folks by Monday morning, with widespread lows in the 30s and 40s, but just a few counties north,  including Alleghany and Bath counties, there are frost and freeze advisories out  for Monday morning for what could be a late nip on some plants.

Meanwhile, the feature at left has been showing up for days on virtually all computer forecast models (this frame is from Saturday evening's Global Forecast System model run, projecting Thursday). The models continue to show an upper-level low circulation developing somewhere near Florida or Cuba and drifting northwest or north through the Gulf of Mexico. In some runs, the system takes root at the surface and appears to develop tropical characteristics. A slow-moving low pressure system is likely in the Gulf of Mexico this week. Though the official start of Atlantic hurricane season is still more than two weeks away (June 1), forecasters will be keeping a close eye on this system just in case it shows signs of becoming a depression, tropical storm or subtropical storm over the warming waters of the Gulf. In time, whatever this system becomes will likely move inland and may affect Virginia's weather a week from now, give or take a day. Lots of time to watch and see if there is a pre-season exhibition of tropical weather.