Center for Satellite Applications and Research (STAR) Review 09 – 11 March 2010 Image: MODIS Land Group, NASA GSFC March 2000 Nearcasting Severe Convection Using the GOES Sounder Robert M. Aune Scott S. Lindstrom Robert M. Aune Scott S. Lindstrom

VISITview Teletraining 2 Requirement, Science, and Benefit Requirement/Objective Mission Goal: Weather and water –Increase lead time and accuracy for weather and water warnings and forecasts –Improve predictability of the onset, duration, and impact of hazardous and severe weather and water events –Increase development, application, and transition of advanced science and technology to operations and services Science Can observations from a geostationary IR sounder be used to predict severe weather outbreaks 1 to 6 hours in advance, filling the gap between radar nowcasts and NWP models? Benefits Reduce loss of life, injury and damage to the economy Better, quicker, and more valuable weather and water information to support improved decisions Increased customer satisfaction with weather and water information and services

VISITview Teletraining Nearcasting uses GOES Sounder Data The GOES Sounder includes three separate water vapor channels The water vapor channels have weighting functions that peak in different parts of the troposphere (longer wavelengths see farther down into the atmosphere) Therefore have a three-dimensional look at atmospheric moisture 3

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VISITview Teletraining 13 Premise: Sounder gives information on distinct layers in atmosphere at observation time Winds from a numerical model can move those slabs of moisture around Question: Where does Convective Instability develop because of the moving slabs? Very Moist Layer Somewhat Moist Layer Very Dry Layer

VISITview Teletraining How is nearcasting done? Data Data include winds and sounder observations of  e and  e that has moved to a point at time=0 and geopotential heights at t=0, 3 and 6h obs time increasing fcst time increasing Start at an initial time. Use a Lagrangian model. Step forward 6 hours. Output hourly forecasts

VISITview Teletraining 15 Nearcasting Severe Convection Using the GOES Sounder Research description –The GOES sounder can provide hourly snapshots of layer-averaged stability parameters. These observations can be assimilated at multiple levels using a simple approach to provide fast, short-term projections of atmospheric stability. Recent science accomplishments (~FY08 to present) –In collaboration with CIMSS, a Lagrangian approach was selected that moves the GOES observations along forward trajectories. Observation error growth remains small to 4 hours and beyond. –GOES sounder retrieved parameters such as equivalent potential temperature (Theta-E) at 750hPa and 500hPa are projected forward 6 hours. Destabilization is indicated when Theta-E 500 (5800m) minus Theta-E 750 (2500m) becomes negative. –The nearcasting model has been tested in real time at CIMSS using the GOES-12 sounder. Products are displayed on the internet ( –Hourly nearcasts are currently being transmitted to NWS Central Region AWIPS for evaluation. –Product will be evaluated at the NWS Storm Prediction Center’s Spring Experiment in May 2010.

VISITview Teletraining 16 Filling the Guidance Gap and Atmospheric Stability Basics 3hr Model Forecast Valid 1700 UTC 7/2/08 Verification 7/2/ UTC Radar 2hr Model Forecast Valid 1700 UTC 7/2/08 The Guidance Gap Very-short-range NWP precipitation forecasts often either: 1) miss significant moisture features 2) have difficulty with exact position and timing of events / phenomena Fill the Gap Between Nowcasting & NWP hours Max Precipitation Axis To detect the development of areas becoming convectively unstable, we need to monitor not only the increase of low level moisture, but areas where low-level moistening and upper-level drying overlap The GOES sounder can detect water vapor at 2-3 layers in a clear atmosphere. Gradients of water vapor can be tracked using multiple GOES sounder scans. Upper level drying over lower level moistening conditions lead to autoconvection. When the layer is lifted the inversion bottom cools less than top and it becomes absolutely unstable If moisture is present in the stable layer and the entire layer is lifted, it can become unstable.

VISITview Teletraining 17 Lagrangian Nearcasting Approach GOES hPa precipitable water analysis valid 21 UTC 13 April 2006 How it works NWP models use randomly spaced moisture observations interpolated on to a fixed grid, and use gridded wind data to advect the moisture information forward in time at fixed grid points. This process smooths horizontal gradients. O Dry Moist Dry Moist GOES hPa precipitable water retrievals valid 00 UTC 14 April 2006 O The Lagrangian approach interpolates wind data to each observation location (~10km spacing) which is then projected forward to a new location forced by dynamically changing wind forecasts. A relatively long time step (10 min) can be used. The new data locations are then transferred back to a regular grid. Starting locationNew location 0-hour Nearcast 3-hour Nearcast

VISITview Teletraining 18 Nearcasts of Severe Weather Low-level Theta-E nearcasts shows warm moist air band moving into far NW Iowa by 2100 UTC. Vertical Theta-E Differences predict complete convective instability by 2100 UTC. 6-hour NearCast for 2100 UTC Mid - Low level Theta-E Differences 6-hour NearCast for 2100 UTC Low level Theta-E Radar indicates rapid development of convection over NW Iowa between 2000 and 2100 UTC, 9 July Correct shape is indicated. 4-hour nearcast of precipitable water lapse rate (mm differences) near Oklahoma City valid 22UTC Feb 10, De-stabilization potential is indicated. Oklahoma City tornado De-stabilization predicted by nearcast

VISITview Teletraining 19 Evaluation by NWS Forecast Office, Sullivan, Wisconsin CIMSS nearcast products are currently being inserted into the operational AWIPS data stream for NWS evaluation. CIMSS precipitable water lapse rate product valid 15UTC April 13, NWS Milwaukee is evaluating the CIMSS precipitable water nearcasting product. The example below shows a good relationship between amount of convective clouds (or lack of them) and strong vertical gradients of PW. 1-hour nearcast of vertical precipitable water differences (mm) valid 19 UTC, July 2, Visible image for 19 UTC, July 2, Red indicates where convection is likely. Black indicates areas where convection is not likely. Same CIMSS nearcast product displayed on an AWIPS workstation.

VISITview Teletraining 20 Challenges and Path Forward Continuing science challenges –Current GOES sounders cannot see low-level temperature inversions and dryness which leads to false alarms –Accurate mesoscale wind information is needed to initialize trajectories Next steps –Assimilate additional products from the GOES sounder to determine which is the best indicator of de-stabilization –Perform Observing System Simulation Experiments (OSSEs) to determine the impact of using a hyperspectral sounder Path into applications/operations –Evaluation at NWS forecast office has commenced (AWIPS, webpage) –Evaluation at Storm Prediction Center Severe Weather Test Bed to commence May, 2010 (supported by GOES-R Risk Reduction)

VISITview Teletraining 21 Nearcasting Severe Weather using a Hyperspectral Environmental Sounder (HES) A WRF model simulation of the June 12, 2002 IHOP case was used to generate simulated radiances from an Advanced Baseline Imager (ABI), a geostationary Hyper-spectral Environmental Sounder (HES), and simulated radar reflectivity. Temperature and moisture profiles were retrieved from the radiance datasets and assimilated by the CIMSS Nearcasting Model and compared. Detailed Theta-E gradients were resolved by HES. 5-hour NearCast for 2000 UTC Low level Theta-E 5-hour NearCast for 2000 UTC Low to Mid level Theta-E Differences Rapid Development of Convection over Texas and Nebraska between 2000 and 2100 UTC 12 June 2002 Strong low-level Theta-E gradients are indicated by HES which has the ability to detect low-level moisture. 5-hour NearCast for 2000 UTC Low to Mid level Theta-E Differences 5-hour NearCast for 2000 UTC Low level Theta-E Weak gradients of low-level Theta-E are indicated by ABI which has only two water vapor channels. Simulated composite reflectivity from nature run indication the formation of convection. Simulated ABI Simulated HES