MD for WFO Sterling - 21:00 UTC

[21:00 UTC] Convection continues to progress east-southeast through my area this afternoon, and is approximately 2/3 of the way through the CWA as of this writing. Ahead of the convection, low level moisture and instability continues to pool (particularly in the south/east portions of the FA), per latest AllSkyLAP Precipitable Water and CAPE fields (see below). Nevertheless, mid-level lapse rates continue to be fairly marginal, so do think that severe hail risk will remain fairly low. With steeper low level lapse rates, wind continues to be the primary threat with this convection, and have already seen several damaging wind reports in my southwest with a localized bowing structure that moved through just before 20:00 UTC. Environment behind the more or less continuous convective structure has been worked over quite a bit, so think that while storm chances will linger, severe threat has pretty much ended in these areas.

As for the storms themselves, have seen a recent drop in cloud top temperatures and jump in cloud top heights with the convection that has just moved through the immediate DC area. Have also seen a corresponding increase in ProbSevere (but more specifically, ProbWind) and these storms will continue to be the main item of interest over the next several hours, particularly as they move into an environment that has become increasingly supportive of storm maintenance.

Fig. 1: AllSkyLAP Layer PW at 20:00 UTC

Fig. 2: AllSkyLAP Layer CAPE at 20:00 UTC

Fig. 3: GOES-East Cloud Top Temperature from approximately 20:00 UTC to 21:00 UTC

Rosie Red