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<br />I <br /> <br />I <br /> <br />I <br /> <br />4. The contractor shall have a good working knowledge and understanding of the principles and <br />parameters that are used for a Probable Maximum Precipitation (PMP) <br />determination/methodology. <br />5. Evaluation of the 20 selected storm events including recent major extreme precipitation <br />events and climatological databases for use in developing quantitative description of extreme <br />precipitation event atmospheric structure. <br />a. Quantify the extreme precipitation (EP) event atmospheric components (single cells vs. <br />multiple cells, movement characteristics, cause oflocation and cause of storm ending) for <br />the key storms identified by the extreme precipitation event committee as the initial base <br />for the state PMP calculation. <br />b. Evaluate and determine the environments for the 20 selected storm events regarding <br />synoptic ridge, surface convergence, upper level support, moisture source, stability of the <br />system, status (weak) upper level wind, wind shear, and soil moisture conditions of the <br />watershed. <br />c. Develop the return frequencies for key meteorological parameters such as, stability; depth <br />of cloud updraft; depth of warm layer; precipitable water index; surface temperature, dew <br />point, wind direction and speed (in combination); standard level (700mb, 600mb, 500mb, <br />400mb, 300mb, 250mb, 200mb) temperature, dew point, wind direction and speed; <br />vertical wind shear, etc. <br />d. Develop return frequencies for the EP atmospheres in the EP events in above task and <br />compare to the climatic return frequencies. <br />6. Re-construction of Extreme Precipitation Events to obtain information on meteorological <br />components and the aerial, temporal and intensity of the event precipitation. <br />a. Prepare reconstruction of noted key EP events: Frijole Creek Storm of 198 I; Plum Creek <br />Storm of June 16, 1965; and others to be determined by the EP committee. <br />. b. Prepare summary analyses of the meteorological components in the sub-cloud and cloud- <br />layers to identify the key atmospheric structures of importance associated with Colorado <br />EP events and to assist modelers in selecting the appropriate atmospheric initial <br />conditions. <br />7. Develop initial conditions for use by 2-D and 3-D atmospheric modelers for storm replication <br />and sensitivity testing. <br />a. Identify and quantify the key meteorological components from Tasks 5 and 6 to define <br />the important features and structures associated with EP events in the sub-cloud layer and <br />the cloud layer. <br />b. Quantify and identify the sub-cloud layer features important to extreme precipitation <br />production, i.e., moisture flux, PBL inversion depth, moisture fetch, wind structure using <br />historic storms in Tasks 5 and 6 for use by regions in the state. <br />c. Identify and quantify cloud-layer features and meteorological components such as <br />vertical wind shear, temp/dew point vertical structure, moisture flux below 500mb, etc <br />using historical storms in Tasks 5 and 6. <br />d. Accomplish steps a-c for any 1997 and more recent EP events which could occur but in <br />more detail using data sets identified prior to the storm season such as WSR-88D, <br />meso net, satellite and other available observation sets, etc. <br />8. Accomplish 2-D and 3-D modeling sensitivity testing and model simulations of the historical <br />and/or 1997 and more recent season EP events to determine the effects of terrain and <br />topography on rainfall distribution, duration and intensity for use in the development of a <br />new PMP methodology. <br /> <br />5 <br />