An Evaluation of the Diagnostic and Prognostic Implications of Orphan Anvils (85)

Chauncy Schultz, NOAA/NWS, Bismarck, ND

Ariel Cohen, NOAA/NWS



The arrival of the GOES-R series of satellites has provided forecasters with a wealth of high spatial and temporal resolution imagery from which they are able to visualize the process of convective initiation with much more detail than ever before. One of the more interesting and relevant diagnostic features regularly observed by the GOES-R series of satellites is the orphan anvil, which is the remnant cirrus from failed updraft attempts. Such orphan anvils can indicate that a capping inversion is weakening and that subsequent attempts at convective initiation may be successful (Line et al. 2016). However, detailed analysis of prolonged attempts at convective initiation and associated extensive orphan anvil generation along a weak surface dryline in North Dakota on 21 July 2017 suggests that orphan anvils can also be indicative of the detrimental effects of dry air entrainment or parcel detrainment on robust updraft development. In this case, a tornadic supercell developed only once the significant orphan anvils spread downwind away from the dryline and into an air mass characterized by higher moisture content above the lifted condensation level. This presentation will illustrate this evolution, compare and contrast it with more transient orphan anvils and their associated environments, and discuss prognostic implications that forecasters should consider when orphan anvils are being generated, including their capability to provide evidence of the strength of high-level storm-relative flow, as they did in the 21 July 2017 case.