UPDATE 8:50 PM, 9/3: Multiple days of occasional showers and squalls spinning around what used to be Isaac
UPDATE 8:50 PM: The flash flood watch has been lifted for Southwest Virginia. While some scattered showers and storms will continue, the threat of locally torrential rain is dwindling. So far, Lane Stadium has stayed almost totally dry as showers have diminished approaching from south. END UPDATE
UPDATE 4:45 PM, 9/3: During the last hour or so, showers and thunderstorms have started banding together more in western North Carolina, as seen on the radar grab at left, with a north-northeasterly movement as they are swirled around the remnant low that was once Hurricane Isaac, now centered near the Indiana-Kentucky border. It is these showers and storms that are expected to move over Southwest Virginia over the next 6 hours or so, getting most if not all locations wet while dumping some locally heavy rains of 2 inches or more — especially in spots where storms or a heavy rain band keeps moving over the same location repeatedly, a process called “training.” It appears likely at this point that rain will begin to move into the Blacksburg area near or shortly before the scheduled 8 p.m. kickoff of tonight’s football game between Virginia Tech and Georgia Tech. A flash flood watch continues for several counties, mostly along the New River Valley and the Blue Ridge (including Roanoke/Salem/Roanoke County) and then eastward along U.S. 460 toward Bedford County and Lynchburg. Rainfall from tropical systems that move inland often peaks in the early evening and overnight hours, rather than daytime, so it is not out of character at all to be getting a “late start” on this possible heavy rain situation. END UPDATE
UPDATE 1:45 PM, 9/3: A flash flood watch has been issued through evening for Roanoke, the New River Valley, counties south along the Blue Ridge and east along the U.S. 460 corridor. This is in anticipation of heavy showers developing later this afternoon and evening. The watch does not mean flooding rain will be widespread, but that heavier showers storms may produce 2 or more inches of rain quickly in local areas. More from NWS-Blacksburg at www.erh.noaa.gov/rnk/. END UPDATE
UPDATE 8:30 AM, 9/3: Keep an eye on the bands of showers moving out of Kentucky and Tennessee today (radar linked here). Over the past 3 days, these bands have weakened in the morning, recharged through the afternoon as temperatures warm, then peaked in intensity and areal coverage during the evening. Additional showers and storms may also develop ahead of the bands as moisture banks against the mountains through the day. END UPDATE
UPDATE 10:30 PM, 9/2: As expected, some folks got heavy rain and gusty winds today (Sunday) in storms — particularly parts of Franklin County and most of Henry County — while others got very little rain at all today. On Labor Day, the coverage of rain is likely to be greater than Sunday, as we start to deal with the bands circulating on the eastern side of what was once Hurricane Isaac (shown on the inset radar grab from Sunday evening on left). Also, there will be some southeasterly surface winds that will bank moisture against the ridges a little more. Just about every location will get wet on Monday, but some will get copious downpours of 2 or more inches, while others get light amounts between the heavier bands. If a band of storms moves over the same area repeatedly for a while, flash flooding could result, and there is some threat of damaging downburst winds in the stronger storms. As for the Virginia Tech game Monday night — take rain gear. It’s possible it won’t pour start to finish (unless one of those training bands of rain sets up right smack over Lane Stadium), but the chances of getting through pre-game festivities and the game itself without any rain is very low. Keep an eye on the radar whatever outdoor plans you have on Labor Day. END UPDATE
Saturday was the first of what could be 4 or even 5 days of dealing with what was once Hurricane Isaac in Southwest Virginia. The satellite photo at left reveals that Isaac still has a very discernible, broad swirl, centered on about St. Louis. It’s spin has swept a lot of tropical moisture northeastward out of the Gulf, helping to trigger Saturday’s round of showers and storms that got heavy in spots in Southwest Virginia. Much heavier rain continued to swirl in narrowing but intense bands through Missouri, Illinois and Arkansas, with some localized flooding, and a spree of tornadoes that caused some damage. Isaac’s old center is slowly unraveling, bumping slowly eastward along a stalling frontal boundary, but spokes of energy and enhanced moisture will rotate through our region each of the next 3 days, possibly even into Wednesday, too. Each new wave will have the potential to trigger showers and thunderstorms that could produce torrential downpours and possibly some localized strong wind gusts, especially when daytime heating energizes the atmosphere a little more. This is unlikely to be a situation where a large area of rain settles in for hours on end, but the frequency and intensity of showers and storms is likely to increase Sunday into Monday, such that just about every location gets some downpours before it passes at midweek. The Hydrometeorological Prediction Center is projecting 5-day totals of 2-3 inches, even more, in most of Virginia as the former Isaac meanders eastward. It’s possible none of the next 4 or 5 days will be a total washout start to finish, but any or all of those days could have periods of time that are a total drenching for an hour or two, maybe longer if a line of storms continues moving over the same location repeatedly. Take your poncho or umbrella anywhere you go.