Mesoscale Discussion 1038
NWS Storm Prediction Center Norman OK
0115 PM CDT Wed Jul 11 2018
Areas affected...Central into eastern Virginia
Concerning...Severe potential...Watch unlikely
Valid 111815Z - 112045Z
Probability of Watch Issuance...5 percent
SUMMARY...Scattered strong storms with isolated, marginal threat for
damaging wind gusts. WW issuance not currently anticipated.
DISCUSSION...Agitated cumulus have become well defined across much
of central and eastern Virginia this afternoon. Convective
initiation has recently occurred and recent CAM guidance suggests
that the development of additional scattered thunderstorms will be
likely within the next few hours. Glancing deep-layer ascent
associated with a weak mid-level shortwave trough, weak confluence
ahead of a southward sagging cold front, and diurnal heating will
act as lifting mechanisms for convection across the discussion area.
Unidirectional effective bulk shear is in place, with speed-driven
effective shear values of generally less than 30 knots noted.
Low-level shear is poor, and RAP point forecast soundings indicate
tall, skinny MLCAPE (up to 1500-2000 J/kg) present owing to poor
mid-level lapse rates on the order of 5-6 C/km. Still, the
atmosphere is moist throughout a deep-layer, with precipitable water
values ranging between 1.7-2.0 inches. Given the deep moisture and
modest buoyancy in place, some of the stronger storms may support
isolated wet downbursts with an associated risk of marginally severe
Given the isolated and marginal extent of the severe threat, no WW
issuance is expected at this time.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 36607923 36757965 36877985 37257996 37547995 37827975
38077948 38347917 38497875 38557857 38537825 38467783
38357744 38117697 37767650 37537624 37397618 37047611
36717630 36657712 36587775 36607923