Colorado Mesoscale Discussion

Areas affected…Southern and Central High Plains

Concerning…Heavy rainfall…Flash flooding possible

Valid 232212Z – 240412Z

Summary…Heavy thunderstorms will continue to develop along an
outflow boundaries of earlier showers and shift east as activity
sags south ahead of a cold front that has pushed through the
Richmond City as of 20Z. Given the lowest flash flood guidance is
over the Hampton Roads metro, the flash flood threat area is
focused there and south to the Albemarle Sound where other low
flash flood guidance is present. These storms are progressive, so
the flash flood threat is localized to where repeating heavy cells
occur and is considered possible through this evening.

Discussion…In the past hour thunderstorms ahead of a front
drifting through southeast VA have produced estimated rain of 0.5
to 1 inch per KAKQ. This activity is expected to intensify as the
front approaches existing boundaries left from earlier showers and
a more unstable airmass that is rather humid. PWATs of 2 to 2.2
inches are across southeast VA which is 2 standard deviations
above normal. SBCAPE of 2500 to 3500 J/Kg has been south of the
current activity this afternoon.

Deep layer 850mb to 300mb mean layer flow is westerly at 25 kt
which is parallel to the boundaries left from earlier activity and
the cold front. This allows a training cell risk as the activity
reaches the flash flood vulnerable Hampton Roads metro area (1hr
flash flood guidance is 1 to 2 inches). FFG is around 2 inches per
hour over rural far southeast VA and areas north of the Albemarle
Sound. Flash flooding is possible over this area with an
expectation for less instability farther south into NC late this


…Please see for graphic product…



LAT…LON 41000383 40940299 40950259 40610229 40170206
39450162 38610110 38150072 37820047 37540028
37020023 36330063 35980238 36020312 36140430
36600424 36990356 37410357 38110373 38800407
39510419 40360442 40900462

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