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Let's be clear -- tonight is still going to be a soggy night. We have already seen some drizzle and light showers, and that will pick up through the evening as upslope winds bring moisture into the higher terrain and we begin to be affected by the front coming from the west. But, as at least one commenter noted earlier, there does appear to be a split in the precipitation to our southwest ... you can see it in the radar grab at the left over central Georgia. What is happening is that the convection to the southeast -- the yellow-colored echoes -- are cutting off some of the northward moisture flow from the Gulf of Mexico. This happens from time to time in our cool-season storm systems, reducing precipiation amounts. But we still have a lot of things working for widespread rain tonight and early Saturday, and we'll probably see this dry slot fill in some as the evening goes along. But it's possible we will see lesser rainfall amounts than earlier thought ... maybe around 3/4 to 1 inch, with locally heavier amounts ... because of the storms to the south cutting off moisture flow.

This big spin of clouds in the central U.S. is a huge upper-level low pressure system that is pulling Gulf of Mexico moisture northward toward us. On Friday, a surface low pressure system will move northeast ward through Southeast U.S., pulling additional moisture our way out of both the Gulf and the Atlantic. Gradually, clouds will thicken and lower through the day Friday, drizzle will begin in some areas as the moist air flows up the eastern side of the mountains, and by afternoon, most areas will be seeing steady rainfall. Heavy rain is possible by Friday night. Thursday evening's rainfall forecast map from the Hydrometeorlogical Prediction Center projects widespread amounts topping 1.5 inches along the Blue Ridge, with some well over 2 inches. Rain will diminish to showers and then end by Saturday afternoon, but a prolonged period of below-normal temperatures appears likely next week in its wake. Some higher elevations will probably see a few snow flurries come Monday or Tuesday night.

 On Thursday, a new Drought Monitor map will be issued showing moderate to severe -- perhaps even locally extreme-- drought continuing over Southwest Virginia. But there is some good news on the way. An upper-level low moving through the central U.S. will begin to lift Gulf of Mexico moisture northward over the next couple of days, topping the cool air mass we have at the surface. An approaching cold front from the west and a developing low pressure system over the Southeast will help to trigger widespread rainfall over Southwest Virginia by late Friday and Saturday ... not good for football games, but great news for our overall dry condition. With some upslope winds possible as the low sweeps by, circulating southeast winds off the Atlantic up against our mountains, rainfall amounts of 1.5 to 2 inches will be possible over much of the region. Behind the storm Sunday, a reinforcement of cold air will move in. The season's first snowflakes may be possible Sunday night at the highest elevations, primarily those typical upslope snow belt areas of southeast West Virginia and far western Virginia. This is the kind of seasonal storm we could stand to see in repetition to ease our long-term drought. If this system's potential is realized, it would be a good start ... though it might mess up your weekend.

A freeze warning has been posted for Thursday morning for locations generally from the Roanoke Valley south and east. This does not mean it won't be getting below freezing in locations west and north of Roanoke ... it just means those areas already had their growing season-ending freeze over the weekend while many places from Roanoke south and east didn't make it to freezing over the weekend, or only briefly reached that mark. In any event, with clear skies and calm winds, it appears that the Roanoke is likely to see its first official freezing weather of the season Thursday morning, so if you haven't already, move tender vegetation inside.  The weather scene will shift from cold weather to the potential of widespread rainfall by Friday and Saturday. More on that later.

With a couple of frosts/freezes having occurred (Roanoke fell to 35 this morning, not quite freezing, but most other area locations did dip to 32 or below), the seemingly late autumn foliage is starting to show more signs of deeper color this week. Since it has been so dry for so long, the color show might be brief ... a few days of color, then fade to brown and hit the ground. But bright sunny days this week with mild temperatures should put us all in the fall feeling. A cold front passing through on Tuesday will reinforce the chilly morning air, but should pass through dry. Rain is possible by the weekend with a new low developing over the central U.S. Other than that, looks like a continued quiet weather pattern for us.

Most of Southwest Virginia is under a freeze warning tonight and Monday morning. While the urban areas of the Roanoke Valley will flirt with the 32-degree mark and possibly hover a couple of degrees above it, most other areas will be a few to several degrees below freezing for 3 or 4 hours early Monday morning. This will effectively bring an end to the growing season across the area. Most areas saw scattered frost and some places dropped below freezing this morning. If you have any surviving tender vegetation outside, tonight is the time to get it inside.

It felt like summer a few days ago ... now, fast-forward to winter. There are whole tangle of overlapping frost and freeze advisories, watches and warnings for our region tonight and Sunday (click here for the latest from the National Weather Service in Blacksburg). For the Roanoke and New River valleys, there is a frost advisory tonight and a freeze watch for Sunday night/early Monday morning. The frost advisory means scattered frost is expected as temperatures dip into the 30s, with the worst frost in sheltered valleys. The freeze watch means that it is possible temperatures could dip below 32 degrees for a few hours Sunday night and early Monday. The city of Roanoke will likely be on the edge of that, maybe sticking a degree or two above freezing, but almost everybody around us will quite likely see the season's first widespread freeze by Monday morning.

Let the record show that, for the first time this season, the National Weather Service in Blacksburg is hinting at a possibility of SNOW late next week ... though just a few flakes in the higher elevations ... in its area forecast discussion. Quoting the weather service:

SHOULD SEE A STEADY DECLINE IN TEMPERATURES TOWARD NEXT WEEKEND AND THE COOLEST TEMPERATURES OF THE YEAR ARE LIKELY. PCPN CHANCES WILL INCREASE AHEAD OF THE UPPER SYSTEM. WE COULD EVEN SEE THE FIRST FLAKES OF THE SEASON IN THE WESTERN MOUNTAINS AS THICKNESSES FALL. IT IS A GOOD TIME TO CHECK YOUR CLOSET FOR COLDER WEATHER GEAR.

Between now and then, we'll see chilly mornings and mild days, broken by occasional frontal passages that may stir up a few showers.

It looks like Roanoke, through 8 a.m., picked up about 2/3 of an inch of rain, and it has continued to rain some since then. A cold front that represents the initial boundary of a change to a more fall-like weather pattern has slowed to a crawl, and rain, developing with the help of an upper level disturbance lifting some Gulf moisture, has only been slowly pushing through. So we've seen a little bit better rain than we expected, though radar now shows it mostly east of Roanoke.  If we could get a rain like this just twice a week, we make major progress against the drought.

Say goodbye to the 80s for highs -- quite possibly for the remainder of 2008. Colder weather is on the way with the arrival of a cold front overnight and another one next week, and it looks like cool weather may hang on for a while. The Climate Prediction Center gives Virginia and neighboring states a good chance of below normal temperatures through the 6-to-10-day and 8-to-14-day periods. Also, interestingly, it rates our chances of above-normal precipitation similarly through the next two weeks, though from here it looks to me like mostly dry frontal passages. We need every drop we can get -- many areas west and southwest of Roanoke, including the New River Valley, were upgraded to severe drought today on the new U.S. Drought Monitor map.

It still remains to be seen exactly how cold we'll get next week, but it will probably be enough for some frost.

On an unrelated note ... we're going to be in the middle of a software change the next few days, so don't be surprised if you see this blog with a different format and missing graphic elements from time to time during the switch.