166 Radar Rainfall Statistics during PECAN

Tuesday, 29 August 2017
Zurich (Swissotel Chicago)
Tammy M. Weckwerth, NCAR, Boulder, CO; and U. Romatschke

The 2015 Plains Elevated Convection At Night (PECAN) field campaign, based in Hays, KS, was designed to understand the causes and improve the predictive skill of the central U.S. nocturnal precipitation maximum. Over 100 instruments were utilized to sample the pre-convective and convective conditions within and around unorganized storms and mesoscale convective systems. Multiple NEXRADs were combined with S-Pol to estimate the quantitative precipitation (QPE).

As expected, the PECAN precipitation maximum occurred overnight from 03-09 UTC (CDT = UTC - 5 hr). Statistics on PECAN QPE highlight the diurnally-modulated regions for rainfall which are dependent upon terrain: the Front Range of the Rocky Mountains (elevation >2000 m) QPE maximum occurred in the afternoon (21-00 UTC), the foothills’ (elevation of 1000-2000 m) maximum QPE occurred in the late afternoon to evening (21-03 UTC) and the plains (elevation <1000 m) maximum QPE occurred overnight (03-09 UTC). Most of the PECAN QPE was associated with advection of mesoscale convective systems (MCSs). Approximately 10% of the total rainfall within the PECAN domain was attributed to pristine convection initiation (CI) events.

Most of the mountain storms were initiated in the afternoon hours (18-21 UTC). The foothills and plains’ CI events occurred most frequently in the late afternoon (21-00 UTC). Further QPE and CI statistics and analyses will be presented.

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