brody_clifton
EF1
As the models have been consistently indicating moderate instability co-located with 50-60kt deep layer shear and favorable low level storm relative helicities over parts of North Carolina and Virginia on Monday, and since there are a handful of chasers besides myself that live in/near the region, I decided to go ahead start a forecast thread for the area for April 3. Upper trough and associated surface cold front will race quickly eastward thru the Carolinas and Virginia during the afternoon and early evening Monday, encountering an increasingly unstable airmass farther east as the afternoon wears on. Although the primary storm mode Monday will likely to be broken bows/lewps, my current thinking is that there will be a relatively small area tomorrow that has a chance of discrete supercells, with locally enchanced 0-3km directional shear (speed shear doesn't look to be an issue anywhere ahead of the front.) Right now, I am especially liking an area along and east of I-95 south/east Richmond, VA and north/east of Rocky Mount, NC sometime during the last 3 hours of daylight Monday. If I had to pick a target city now, I'd say Murfreesboro, NC at the intersections of Hwy 158/258 along the NC/VA border. Areas north of there are likely to be under a rain sheild and/or thick clouds throughout most of the afternoon, and any convection to the north is likely to be strongly forced into one or more lines, whereas areas south and southwest of the target also look to be much more linearly forced with nearly unidirectional shear from 0-6km agl.
My reasoning behind this target: 4/2/06 12Z NAM, as well as previous runs, is showing a strong dry punch at 700mb from western South Carolina ENE across southeastern NC, with this dry air nosing into northeastern NC to just south/SW of the target area by 00Z. The dry punch should focus surface convergence north of it, while at the same time helping to clear out any non-anvil WAA-related low/mid level clouds that may exist over the TA during the early afternoon hours. The NAM indicates a secondary surface low (meso low?) will develop along the triple point across northeast WV during the late afternoon and move east into northern VA by early evening, as the primary surface low continues to track NE near Ontraio, Canada. This secondary low should help back the winds in the TA so that they have at least some eastlerly component to them. I'm not sure if I agree with the pure southeast (135 degree) winds the NAM has forecasted for most of the TA, but I do feel that at least SSE surface winds are not out of the question in the area. Forecasted storm motions range from 265-280 degrees from north to south across the TA, so even southerly surface winds would allow for 70-80 degrees of 0-6km directional shear. However, with nearly unidirectional flow from 850mb - 500mb likely, southerly or SSE surface winds would also mean 70-80 degree of directional shear from the surface to 850, leading to 0-1km storm relative helicities from 150-250 m^2/s^2 from south to north across the TA.
My primary concern for tomorrow is storm mode, but I'm thinking there is a chance for discrete supercells in the target area. Although the western edge of the temperature axis is forecasted to be oriented SW to NE across the region, the western 60 degree isodrosotherm is forecasted to be lined up generally south to north, even taking on a 'negative' tilt over far northeastern NC at 00Z, likely due to the strong dry punch at 700mb to the south. West-southwesterly 500mb flow would cross the western edge of the dewpoint axis at nearly 90 degrees in this area, increasing the likelihood of discrete convection.
To sum it all up, severe storms are likely across southeastern VA and northeastern NC on Monday, although the development of discrete supercells and tornadic activity will strongly depend of the development and timing/position of the secondary surface low late Monday afternoon/early evening.
My reasoning behind this target: 4/2/06 12Z NAM, as well as previous runs, is showing a strong dry punch at 700mb from western South Carolina ENE across southeastern NC, with this dry air nosing into northeastern NC to just south/SW of the target area by 00Z. The dry punch should focus surface convergence north of it, while at the same time helping to clear out any non-anvil WAA-related low/mid level clouds that may exist over the TA during the early afternoon hours. The NAM indicates a secondary surface low (meso low?) will develop along the triple point across northeast WV during the late afternoon and move east into northern VA by early evening, as the primary surface low continues to track NE near Ontraio, Canada. This secondary low should help back the winds in the TA so that they have at least some eastlerly component to them. I'm not sure if I agree with the pure southeast (135 degree) winds the NAM has forecasted for most of the TA, but I do feel that at least SSE surface winds are not out of the question in the area. Forecasted storm motions range from 265-280 degrees from north to south across the TA, so even southerly surface winds would allow for 70-80 degrees of 0-6km directional shear. However, with nearly unidirectional flow from 850mb - 500mb likely, southerly or SSE surface winds would also mean 70-80 degree of directional shear from the surface to 850, leading to 0-1km storm relative helicities from 150-250 m^2/s^2 from south to north across the TA.
My primary concern for tomorrow is storm mode, but I'm thinking there is a chance for discrete supercells in the target area. Although the western edge of the temperature axis is forecasted to be oriented SW to NE across the region, the western 60 degree isodrosotherm is forecasted to be lined up generally south to north, even taking on a 'negative' tilt over far northeastern NC at 00Z, likely due to the strong dry punch at 700mb to the south. West-southwesterly 500mb flow would cross the western edge of the dewpoint axis at nearly 90 degrees in this area, increasing the likelihood of discrete convection.
To sum it all up, severe storms are likely across southeastern VA and northeastern NC on Monday, although the development of discrete supercells and tornadic activity will strongly depend of the development and timing/position of the secondary surface low late Monday afternoon/early evening.
In all seriousness, would be a good test run before we track out to the Midwest in Mid-May. 
