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<br />""_.:.;.""".~'!f._-.;.o_,,,'_ <br /> <br />" <br /> <br />-- " <br /> <br />-~~ _c.,"" - <br /> <br />:11"' <br /> <br />-..._~ <br /> <br />- ~~ '.~"" <br /> <br />Attachment JJ <br /> <br />SEEDING CRITERIA <br /> <br />The selection of suitable cloud systems for seeding operations will be based <br />on an evaluation of multiple meteorological and cloud physics parameters, <br />It is the understanding that the following criteria will be adhered to: <br />, <br /> <br />a. Cloud base water - Natural Precipitation. Cloud systems with a <br />a cloud base water content of 1.5 gms/kgm (North Sector) to <br />1.8 gms/kgm (South Sector) or greater will be considered as <br />potentially seedable. In this consideration a weather system <br />will be evaluated for seeding potential if it is determined <br />that at least natural precipitation is likely to occur. <br /> <br />b. Effective temperature Pre-trough or Pre-frontal. Cloud <br />systems with a 500 ME temperature of -270 C or warmer will <br />be considered as potentially seedable. <br /> <br />c. Effective temperature Post-trough or Post-frontal. Cloud <br />systems with cloud top temperatures of _270 C (North Sector) <br />to _300 C (South Sector) will be considered as potentially <br />seedable. <br /> <br />d. Barrier level winds. Wind speeds from favorable directions at <br />heights approximately 2,000 feet above the seeded barrier of <br />30 knots or less for pre-trough cloud types and up to '10 knots <br />or less for post-trough clouds will be considered as potentially <br />favorable for seeding treatment. Some adjustments are made to <br />the acceptable wind velocity ranges depending on the width of <br />the barrier to be seeded. <br /> <br />e. Cloud base height. Cloud systems with bases less than 2,000 <br />feet above the mean barrier height will be considered as <br />potentially seedable. <br /> <br />f. Additional weather system considerations. Additional adjustments <br />will be made on the seeding rate or the seeding potential of a <br />cloud sys tem based upon the depth of the cloud sys}em to be <br />seeded, whether the cloud system is indicating rejdevelopment or <br />is near its dec.aying stage and whether the cloud.lsystem has a <br />potential source of abundant natural nuclei from higher cloud <br />systems. <br /> <br />Once a weather system is considered seedable by evaluating the <br />above cloud and meteorological parameters, an appropriate seed <br />rate is calculated for the initial portion of the weather system. <br />As the forecast and observed parameters of the weather system <br />change seeding rates t1re re-evaluated and changed as is necessary <br />r or l he new or cxpcc tC'cl c'1 oud cnnd it ions. <br />