An Observational Study: Real-time Use of the NSSL
Experimental Warn-on-Forecast System for Ensembles during NWS Severe Weather
Operations (216)
Katie Wilson, OU
CIMMS/NOAA NSSL, Norman, OK
Patrick Skinner, OU
CIMMS/NOAA NSSL
Todd Lindley, NOAA
NWS
Randy Bowers, NOAA NWS
Doug Speheger, NOAA
NWS
Abstract:
Currently, National Weather
Service (NWS) forecasters follow a warning decision process that uses real-time
observations and reports to detect imminent or occurring weather threats.
However, improvements in warning lead time have not occurred in this
warn-on-detection paradigm in recent years. Therefore, a need for forecast
information that enables earlier anticipation of weather threats has been
recognized. Tasked with addressing this need, the NOAA Warn-on-Forecast project
is developing and testing a convection-allowing ensemble analysis and
prediction system that provides probabilistic guidance for a variety of weather
threats within the watch-to-warning timeframe. This prototype system, termed
the NSSL Experimental Warn-on-Forecast System for ensembles (NEWS-e), provides
real-time short-term forecast guidance. These forecasts are provided on the
regional-scale, with the position of the NEWS-e grid (750km^2 x 750km^2) being
based on Day 1 convective outlook guidance from the Storm Predication Center
and Weather Prediction Center.On days in spring 2017 when the NEWS-e grid was
placed over the Norman Weather Forecast Office (WFO) domain, real-time NEWS-e
guidance was provided to forecasters during operations. Briefings from a
Cooperative Institute for Mesoscale Meteorological Studies (CIMMS) scientist on
NEWS-e output proved useful to aiding forecasters' interpretation of this
probabilistic guidance. Most notably, the NEWS-e output had a considerable
impact on forecasters' decision making on 16 May 2017, when forecasters decided
to issue an advisory expressing that there was &ldquoa high probability
that tornado warnings will be issued&rdquo in western Oklahoma. Approximately
two hours later, an EF-2 rated tornado touched down in Elk City, Oklahoma,
resulting in one fatality and eight injuries.Given the success of this first
introduction of NEWS-e output to the Norman WFO, this collaborative effort will
continue in spring 2018. In addition to a CIMMS scientist providing briefings
and interpretative support to forecasters, a second CIMMS scientist will engage
in observational activities. These observations will take place within the
naturalistic operational environment, and will be both direct (i.e.,
forecasters will be aware that observations are being made) and continuous
(i.e., observations will made within the same operational setting as often as
possible). Observations will be semi-structured, such that they will be
designed to capture certain elements of the decision making process while also
being largely driven by what activities emerge during real-time operations.
These observations are expected to bring to light: 1) how forecasters draw
meaningful information from the NEWS-e output, 2) the ways in which this
information can be subsequently useful to their decision making within the
watch-to-warning timeframe, and 3) what adjustments or modifications
forecasters must make to their normal workflow to integrate this new information
effectively. The qualitative data will be analyzed descriptively within context
of their particular situations, and early findings from this analysis will be
presented at this conference.