The Orographic Rain Index (ORI) Product at CIRA

The CIRA Orographic Rain Index (ORI) product at CIRA is a short-term forecasting tool that predicts where land-falling moisture plumes will interact with strong terrain gradients in the form of an index. ORI is the product of moisture and terrain-induced “lift”. The moisture data comes from the CIRA blended TPW product and the terrain information comes from the USGS GTOPO30 elevation data, therefore the product is 1 km horizontal resolution. Wind data currently comes from the GFS 850 mb, but can be adapted in the future. ORI is designed to indicate to forecasters where there is short-term (0-3 hr) potential for heavy orographic rain. Increasing values of ORI (up to the set threshold of 250) represent an increasing probability of orographic enhancement (if precipitation is occurring).

Discussion of background motivation for the product will be addressed, followed by cases that illustrate strengths and weaknesses. Product validation efforts will also be covered. This product is part of the CIRA GOES-R Proving Ground suite of products available in AWIPS. A brief summary on the effort to transition this into a product for AWIPS will be provided. A VISIT (Virtual Institute for Satellite Integration Training) training module was developed to provide interpretation guidance for forecasters. The training module can be easily updated as the product matures and is updated based on validation efforts and user feedback. Future efforts to improve the ORI product include 1) development of a smoothed version in response to forecaster feedback that felt the scale of was too fine, 2) flexible upslope layer winds and 3) leveraging the orographic model utilized by NWS WFO in Boulder, CO that was developed by Owen Rhea.