2009.04.24
"See Text": The fly in the ointment on a summerlike spring weekend
UPDATED 9:30 AM SATURDAY FOR NEW MAP LINKS
The Storm Prediction Center has Southwest Virginia and nearby parts of the central and southern Appalachians in western Virginia, West Virginia, North Carolina and Tennessee under a "See Text" on Saturday. (Click here for severe risk map) This denotes a region of potential strong to locally severe thunderstorms that doesn't quite warrant a "slight risk," and the "See Text" refers Web visitors to the discussion underneath the map. (Current Day 1 or Saturday discussion linked here) The text notes that southerly winds on the back side of a developing high (the one that is going to bring us several days of summerlike temperatures) may deliver just enough moisture into an air mass that may be just unstable enough (with some cooler air aloft) for a few thunderstorms to develop along the mountain ridges as tempereatures soar close to 90 on Saturday. It is possible that a few of these storms may produce large enough hail ... 3/4 inch or larger ... or put out a wind gust of 58 mph or greater to warrant a severe thunderstorm warning.
Really, this is like many afternoons in July or August when temperatures get hot and the daytime heating, combined with a few other marginal factors, is enough to trigger a few thunderstorms. If you happen to be under one of these storms, it might be momentarily spectacular, but most people will not be under one on Saturday. Don't be surprised to hear a distant rumble of thunder even if it stays sunny and warm where you are. The storm threat for any particular location is very low, and no reason to cancel outdoor plans entirely ... but just enough to keep an ear and eye out for any suddenly developing storms.
"See Text" advisories sometimes go away and sometimes turn into "Slight Risk" zones depending on how things come together.
The atmosphere is expected to become more stable Sunday through Tuesday as high pressure continues to build and the atmosphere warms and stabilizes at all levels, so chances of storms will dwindle from slight to miniscule as the mercury possibly challenges 90 each of those days.
RSS feed 
The April heat wave is under way. Roanoke hit 85 this afternoon, and Blacksburg appears to have reached at least 84. Bluefield, W.Va., set a new April 24 record high of 82.
Comment by Kevin Myatt — April 24, 2009 @ 5:28 pm
Some thunderstorms have fired this evening in northwest North Carolina with a severe thunderstorm warning east of Boone.
Comment by Kevin Myatt — April 24, 2009 @ 6:47 pm
We actually could see the cloud tops of those storms up here in the NRV off in the distance, it was pretty wild. Very clear anvil shapes off in the southern sky. The sunset lit them up with a nice pinkish-orange shade.
Comment by Other John — April 24, 2009 @ 8:51 pm
Saw, some lighting in the distance, playin baseball tonight in Galax. We won 16-3 btw. haha. ( Galax won, that who I play for).
Comment by Zach — April 25, 2009 @ 1:08 am
Interesting observation overnight at Roanoke Regional Airport: temperature was 67 at 11 p.m. and then shot up to 73 by midnight.
Why? My conclusion would be that the winds were calm at 11 p.m. but then turned out of the west-southwest at midnight, creating a slight downsloping effect that warmed the surface temperature slightly.
Comment by Kevin Myatt — April 25, 2009 @ 11:13 am
Great job by the forecast models. A "ribbon" of showers and storms developing along the ridges right on cue this afternoon.
Comment by Jp — April 25, 2009 @ 4:24 pm
We just had a nice thundershower in New River. I could see it developing down toward Peak Mountain in Pulaski, and it worked it's way up to the ENE. Not a lot of rain, and not any severe lightning, but a few rumbles, a short burst of heavy rain, and a bit of wind before the storm. ught to cool things down slightly before the humidity builds back when the sun returns.
Comment by Other John — April 25, 2009 @ 4:48 pm
These storms are unusually high-based for this area ... Roanoke's 4 p.m. temperature was 88 and dew point was 48, a 40-degree difference ... generally speaking the wider the difference the higher the cloud bases ... I'm noticing virga (rain evaporating before hitting the surface) over the Roanoke Valley now ... the potential problem with high based storms is dry lightning that could spark fires.
Comment by Kevin Myatt — April 25, 2009 @ 4:55 pm
Windy burst of dust and sprinkles in downtown Roanoke with one of the collapsing storms ... estimated 45 mph wind gusts, plastic bags flying everywhere.
Comment by Kevin Myatt — April 25, 2009 @ 5:04 pm
I totally agree with you on Saturday, Mr. Myatt that this paticular storm, though it may have been only single cell on last Saturday, after the noon time, not only pick up the dust, but I notice in the window looking towards Salem and my location being NW closer to the Roanoke Regional Airport, that the wind started to whirl the dust around going up my drive-way. I believe it to be a gustnado that only lasted for a few seconds. The storm was sucking the convective heat pretty hard like a super-cell would with winds constantly shifting SW and NE. This proves that single cell thunderstorms can produce gustnados, even if the dewpoint and relative humdity is not very high at all. New espotter in Roanoke who have watch the espotter's presentation, ought to try the skywarnonline.com website which is very educational and you can communicate and send data to one another or the NWS.
Comment by Espotter Watchdog — April 27, 2009 @ 4:40 pm