UPDATE 11 PM, 10/5: Karen has weakened to a tropical depression and is not expected to re-strengthen. Expect another warm day with lots of highs in the 80s Sunday before the approaching cold front brings showers and thunderstorms for Monday. END UPDATE
“Tropical Storm Karen takes center stage,” I wrote for a headline on the last blog post. Nope.
The graphic at left — a little bigger by clicking here — shows Karen’s problem clearly, as of late Friday night. The circulation center of Karen is visible on this infrared satellite picture spinning in the central Atlantic south of Louisiana. But the storms and rain are hundreds of miles EAST of tthe circulation center. This is what the National Hurricane Center meant Friday night in a discussion when it said Karen had been “decapitated” — strong winds aloft have literally blown the rain bands and storms that wrap around the circulation in a healthier storm well away from the center of the spin. Tropical systems don’t last long like this — unless new convection develops around that circulation center, Karen will be a goner on Saturday.
Meanwhile, the real weather action in the country has been in the Northern Plains, with some places getting more than three feet of snow in western South Dakota, while destructive tornadoes have roared a couple hundred miles east in eastern South Dakota and Nebraska and western Iowa. This was the result of a powerful low-pressure system that created a sharp boundary between cold air from Canada on the west side and warm, moist air on the east side. Here is a link to video of a large wedge tornado responsible for some destroyed homes near Wayne, Nebraska, in the northeast part of the state.
So where does this leave Southwest Virginia’s weather? First of all, expect an unseasonably warm, dry Saturday, with highs again topping out in the 80s, maybe a few spots near 90. (Roanoke hit 86 on Friday, Blacksburg 82, compared to normals of 72 for Roanoke and 69 for Blacksburg, but short of records 91 and 85, respectively.) As it looks now, Sunday may be similar, though late in the day there will be an increasing chance of showers and storms. The strong low to the north responsible for the Plains blizzard/tornadoes will drag a cold front toward us and also pull up Gulf moisture. Karen — at least as a circulation center that continues inland – likely plays a lesser role in our early week weather, unless it re-flares Saturday, but some of its remnant moisture may still get caught in the southerly flow ahead of the front. Widespread torrential rainfall amounts are looking less likely, but some significant rain and a few thunderstorms probably will occur on Monday as the front approaches.