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The synoptic-scale weather conditions preceding and following the ill-fated Space Shuttle Challenger launch are documented, with particular emphasis on the upper-level winds for central and northern Florida. Operational radiosonde data collected by the National Weather Service, visible and infrared imagery from the Geostationary Operational Environmental Satellite, and water-vapor imagery from the VISSR (Visible Infrared Spin Scan Radiometer) Atmospheric Sounder, ozone data collected by the Total Ozone Mapping Spectrometer aboard the Nimbus-7, and soundings collected at Cape Canaveral (XMR) are described. Analyses derived from these data sets point to the juxtaposition of two distinct jet-stream systems (a polar-front jet [PFJ] and a subtropical jet [STJ]) over north-central Florida on the morning of the launch. Both jets were characterized by regions of significant vertical wind shear, which was especially strong above and below the core of the STJ.
Data from a radiosonde released at Cape Canaveral 10 min after the shuttle accident combined with radiosonde and jimsphere wind measurements before the shuttle launch reveal that, over XMR, the magnitude of the maximum wind in the PFJ was increasing with time while the magnitude of the STJ was decreasing. Even with the decreasing magnitude of wind speeds in the core of the STJ over XMR, large vertical wind shears and low Richardson numbers were still diagnosed near the PFJ and beneath the core of the STJ at the time of launch (1639 GMT). The low Richardson numbers associated with the presence of vertical wind shear indicate that conditions were favorable for shear-induced turbulence at the time of the shuttle explosion.
The results from the analyses of the synoptic radiosonde data are inconclusive due to the poor temporal and horizontal spatial resolution of the observational data base and the large number of missing data reports at numerous stations in the southeastern United States (including XMR). In an attempt to overcome this deficiency, numerical simulations of the atmospheric conditions were conducted using a mesoscale numerical model. The simulations initialized at 1200 GMT 28 January confirm the juxtaposition of two distinct jet systems over north-central Florida at the time of the shuttle launch and the presence of large vertical wind shears and low Richardson numbers associated with these jets.
Given the rapid temporal evolution of atmospheric flow regimes which involve strong wind shears, we recommend that consideration should be given to 1) augmenting the observations (both in time and space) upstream and around the Cape Canaveral launch facility, 2) enhancing the analysis and display capabilities of these data, and 3) using numerical-model output to provide the best possible diagnosis and forecast of the meteorological conditions for future shuttle launches.
The synoptic-scale weather conditions preceding and following the ill-fated Space Shuttle Challenger launch are documented, with particular emphasis on the upper-level winds for central and northern Florida. Operational radiosonde data collected by the National Weather Service, visible and infrared imagery from the Geostationary Operational Environmental Satellite, and water-vapor imagery from the VISSR (Visible Infrared Spin Scan Radiometer) Atmospheric Sounder, ozone data collected by the Total Ozone Mapping Spectrometer aboard the Nimbus-7, and soundings collected at Cape Canaveral (XMR) are described. Analyses derived from these data sets point to the juxtaposition of two distinct jet-stream systems (a polar-front jet [PFJ] and a subtropical jet [STJ]) over north-central Florida on the morning of the launch. Both jets were characterized by regions of significant vertical wind shear, which was especially strong above and below the core of the STJ.
Data from a radiosonde released at Cape Canaveral 10 min after the shuttle accident combined with radiosonde and jimsphere wind measurements before the shuttle launch reveal that, over XMR, the magnitude of the maximum wind in the PFJ was increasing with time while the magnitude of the STJ was decreasing. Even with the decreasing magnitude of wind speeds in the core of the STJ over XMR, large vertical wind shears and low Richardson numbers were still diagnosed near the PFJ and beneath the core of the STJ at the time of launch (1639 GMT). The low Richardson numbers associated with the presence of vertical wind shear indicate that conditions were favorable for shear-induced turbulence at the time of the shuttle explosion.
The results from the analyses of the synoptic radiosonde data are inconclusive due to the poor temporal and horizontal spatial resolution of the observational data base and the large number of missing data reports at numerous stations in the southeastern United States (including XMR). In an attempt to overcome this deficiency, numerical simulations of the atmospheric conditions were conducted using a mesoscale numerical model. The simulations initialized at 1200 GMT 28 January confirm the juxtaposition of two distinct jet systems over north-central Florida at the time of the shuttle launch and the presence of large vertical wind shears and low Richardson numbers associated with these jets.
Given the rapid temporal evolution of atmospheric flow regimes which involve strong wind shears, we recommend that consideration should be given to 1) augmenting the observations (both in time and space) upstream and around the Cape Canaveral launch facility, 2) enhancing the analysis and display capabilities of these data, and 3) using numerical-model output to provide the best possible diagnosis and forecast of the meteorological conditions for future shuttle launches.
The Howard A. Hanson Dam (HHD) has brought flood protection to Washington's Green River Valley for more than 40 years and opened the way for increased valley development near Seattle. However, following a record high level of water behind the dam in January 2009 and the discovery of elevated seepage through the dam's abutment, the U.S. Army Corps of Engineers declared the dam “unsafe.” NOAA's Office of Oceanic and Atmospheric Research (OAR) and National Weather Service (NWS) worked together to respond rapidly to this crisis for the 2009/10 winter season, drawing from innovations developed in NWS offices and in NOAA's Hydrometeorology Test-bed (HMT).
New data telemetry was added to 14 existing surface rain gauges, allowing the gauge data to be ingested into the NWS rainfall database. The NWS Seattle Weather Forecast Office produced customized daily forecasts, including longer-lead-time hydrologic outlooks and new decision support services tailored for emergency managers and the public, new capabilities enabled by specialized products from NOAA's National Centers for Environmental Prediction (NCEP) and from HMT. The NOAA Physical Sciences Division (PSD) deployed a group of specialized instruments on the Washington coast and near the HHD that constituted two atmospheric river (AR) observatories (AROs) and conducted special HMT numerical model forecast runs. Atmospheric rivers are narrow corridors of enhanced water vapor transport in extratropical oceanic storms that can produce heavy orographic precipitation and anomalously high snow levels, and thus can trigger flooding. The AROs gave forecasters detailed vertical profile observations of AR conditions aloft, including monitoring of real-time water vapor transport and comparison with model runs.
The Howard A. Hanson Dam (HHD) has brought flood protection to Washington's Green River Valley for more than 40 years and opened the way for increased valley development near Seattle. However, following a record high level of water behind the dam in January 2009 and the discovery of elevated seepage through the dam's abutment, the U.S. Army Corps of Engineers declared the dam “unsafe.” NOAA's Office of Oceanic and Atmospheric Research (OAR) and National Weather Service (NWS) worked together to respond rapidly to this crisis for the 2009/10 winter season, drawing from innovations developed in NWS offices and in NOAA's Hydrometeorology Test-bed (HMT).
New data telemetry was added to 14 existing surface rain gauges, allowing the gauge data to be ingested into the NWS rainfall database. The NWS Seattle Weather Forecast Office produced customized daily forecasts, including longer-lead-time hydrologic outlooks and new decision support services tailored for emergency managers and the public, new capabilities enabled by specialized products from NOAA's National Centers for Environmental Prediction (NCEP) and from HMT. The NOAA Physical Sciences Division (PSD) deployed a group of specialized instruments on the Washington coast and near the HHD that constituted two atmospheric river (AR) observatories (AROs) and conducted special HMT numerical model forecast runs. Atmospheric rivers are narrow corridors of enhanced water vapor transport in extratropical oceanic storms that can produce heavy orographic precipitation and anomalously high snow levels, and thus can trigger flooding. The AROs gave forecasters detailed vertical profile observations of AR conditions aloft, including monitoring of real-time water vapor transport and comparison with model runs.
