presented by Jim Wilson and Rita Roberts
The data rich IHOP_2002 experiment is used to study convective
storm initiation and subsequent evolution for all days of the experiment.
Storm initiations were grouped into 112 initiation episodes. Initiation
episodes were almost evenly divided between those triggered along
surface based convergence lines and elevated initiation episodes
that showed no associated surface convergence. Surface-based initiations
were mostly associated with synoptic fronts and gust fronts and
less so with dry lines and bores. Elevated initiations were frequently
associated with observable convergent or confluent features in
the RUC wind analysis fields between 900 and 600 hPa.
The evolution of the initiation episodes covered a great range
of situations including intense supercells, squall lines, mesoscale
convective systems, short lived convective lines, and short lived
unorganized groups of storms. The evolution and lifetime of the
initiation episodes was closely tied to the development of gust
fronts.
A 10 km version of the operational Rapid Update Cycle (RUC10)
numerical forecast model was specifically run by the NOAA Forecast
System Laboratory for IHOP. The ability of the RUC10 to make 3
and 6 hr forecast of thunderstorm initiation, movement and evolution
is examined. The RUC10 frequently captured the initiation although
it was often too early, too extensive and misplaced. Once the gust
fronts developed and the system propagated with the gust front
the RUC failed to move the precipitation accordingly.
Seminar is from 9:30-10:30 am at FL2-1022 on Tuesday, November
9, 2004.
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