Laserfiche WebLink
<br />/ <br /> <br />.4!. ,~J_ ~__~__ ' <br /> <br />target area. If the wind speed is too strong, there will be a blow-over effect <br />where there is insufficient time for snow development and fallout before passing <br />downwind of the mountain crest and the target area. WWCI has determined that <br />the height to use in determining this wind speed is 14,000 ft. msl, and that <br />the critical wind speeds are 10-30 knots in pretrough situations and 10-40 knots <br />in posttrough situations. <br />The forecasts for wind direction and wind speed over the target areas are <br />based on an examination of all available NWS data and analyses (listed in <br />Section 2). Specifically, we use the latest rawinsonde data from Grand Junction <br />and Denver extrapolated to the target area locations for initial conditions. We <br />then use available wind (9,000, 12,000 and 18,000 ft.) forecasts from the NWS <br />Limited Fine Mesh (LFM) model and our in-house evaluation of the accuracy of <br />this model (the model accuracy changes and needs to be continually evaluated), <br />to arrive at our operational wind forecasts over the target area for the next <br />24-hour period. These wind speed and direction forecasts for the 10,000 ft., <br />14,000 ft. and 18,000 ft. levels are plotted on the cross-sectional sketch of <br />forecast weather conditions mentioned earlier in Sections 1 and 2. This visual <br />picture is used to document our forecasts, to track conditions during a seeding <br />operation and for verifying the clou~ temperature and wind forecasts. <br /> <br />-5- <br />