92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Wednesday, 25 January 2012: 2:00 PM
Tests of Objective Short-Range Forecasts of the Pre-Convective Environment Using Geostationary Satellite Data
Room 343/344 (New Orleans Convention Center )
Ralph A. Petersen, CIMSS/Univ. of Wisconsin, Madison, WI; and R. M. Aune

Multi-spectral instruments aboard current and future geostationary satellites resolve atmospheric features at extremely high resolution both in time and space. A major benefit from these detailed and frequently refreshed geostationary satellite data comes from assisting forecasters to identify rapidly developing, extreme weather events 1-9 hours in advance. In order to detect the rapid, localized destabilization that precedes convective initiation, objective tools have been developed which 1) detect and retain extreme variations in the atmosphere, 2) incorporate large volumes of high-resolution asynoptic data, and 3) provide guidance products to forecasters within minutes of the time when updated satellite observations become available. Because of the detail and perishable nature of these very-short-range forecast products, numerical approaches are used that are notably different from conventional NWP.

At previous meetings, a Lagrangian “NearCasting” approach was shown that optimizes the impact of information provided by multi-channel IR instruments on geostationary satellites, specifically preserving intense vertical and horizontal variations present in the moisture and temperature fields observed through repeated observations. Results using both GOES and Eumetsat-SEVERI data showed that the Lagrangian system can both 1) capture and conserve details (e.g., maxima, minima and extreme gradients) observed in the multi-spectral IR satellite product that provide useful detail not present in the NWP first guess fields used for these products, and 2) predict the development and changes of vertical moisture and stability structures critical for determining the timing/location/intensity of convection in the near future, even for times after IR satellite data are no longer available due to obscuration by the developing cloud shields.

Previous examples have demonstrated that NearCast products using full-resolution SEVIRI or GOES data are useful in predicting isolated severe convective events not captured in convection NWP guidance. Results presented here will further expand our understanding of how best to transition existing and future geostationary observations and NearCast products into operations. The presentation will focus on: 1) Additional case studies over the US for a range of convective events strength, and 2) Real-time forecaster assessments at NCEP's Storm Prediction and Aviation Weather Centers (including discussion of new options for short-range validation). These results will provide evidence of the benefit that future GOES and Meteosat observations will have on improving future convective forecasts, both in further isolating the likely location/timing of development and in providing enhanced information about probable storm intensity/longevity. Because of the desire both to reduce false alarms and increase probability of detection (which have different impacts on SPC and AWC operations), both destabilization and stabilization are studied.

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