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<br />.1) ~ount8!n-~;~nt~t'ated c'..> l::i and cold front
<br />stOfms produced tho..: _~;trg~~t sci.ltional ralnf,l;.~_~.
<br />A.!.~uss-generateJ c'..> I:i proc:!uCCG t.he least.
<br />I 2) ~!ountaln-g!..'",~ri1ted C!> f S and upper-level
<br />,:troughs produced t:\~ ~~t'~ate:!:it num~er of hour::)
<br />with rainfall dur.!.n~.'. ':~H.~ season. The upslo:)(:
<br />Iscorm produced tht! least.
<br />,: 3) }~ounta.ln-gC!II.! rated ell t s !!'.ost often pro-
<br />duced rain during, L~l~ evening uue! nighttlw~ !lours.
<br />"All storm ty-pes t;!XC 0..: 1l t the urslope cas~ were
<br />"lellst act1v~ bctWt.'l'll I)<)IJO-1100 ~~)T.
<br />4) Overall, !lluu.\taln-gcnerated Cb's, cold
<br />::front storm.s, and uP:I.~r-levcl troughs produccll
<br />;:the greate::Jt modc:!..'...ed changes in ?cecipltation
<br />:during the period, \Jl\i.!.e airmass-generated Cb' s
<br />,produced the least.
<br />5). Applying mo~el B to all storm types, one
<br />,might expect an ar"':it': rainfall :!..ncrease of 3', mm
<br />':during the !-!ay thrult!~h July s~n~on. ~1ounCa:!..n-
<br />Ilg~nerated Cb's, cc.l~cl ~ront storms and upp~r-..!.evel
<br />'troughs account for 2~ mm (857.) of the increase.
<br />
<br />Based on these results, the three sto~
<br />types which appear. t," have the greatest potential
<br />fur Incre..a.:;ec. ra:lnf.:d.'... ar~ T!1QI;lnta!.n.~encrat:o..:d Cb's,
<br />cold franc scarm::>, and upper-J.evt:l troughs. ~he
<br />10101 frequency and raen productlo<1 of airmass Cb's
<br />I indicate th~y have li!1:1ted potential fot' rain
<br />augmentation. !~ow~vt:.!', it shuulJ be remem'Jcred
<br />that these results arc based on simple hypo':heti-
<br />cal variab!.e-c!1B!lge mudels that do not consider
<br />the microphysical (lnL dynamical characteristics
<br />of the cloud systems.
<br />
<br />A large pOl:tion of ehe rainfall from
<br />:: the mountB.in-gt!ncr~ltl.,'t.! Cb's occurs after dar't at
<br />~(iles City. Pr~15.!~!lllary aircrafe studies o~ these
<br />, storm syst~m9 during 1976 have :!.ndicated th~t they
<br />: may not be susceptib',e to cloud seeding by this
<br />time. The activ~ convection ten(.~s to be well
<br />within the cloue sys':em by dark, and the visilJ.!.e
<br />; portions of the C:l".:t! sys t:em ulJuve the freezing
<br />1.evel are characte!.".t:~ed by hi~~lt ice crystal con-
<br />I centrations and 10''''' ~.!.quJ.d. wtltt:~r content~. Ba::led
<br />: on these findings, ~_!: ,JUS decl~ec!. to expand t~le
<br />,I }!11~s Cley re:::leLl L'I..:!\ ;n:c8 to ine tude th~ tl'oun!:i1in
<br />ranges SOUt.!l anc! WcS: 0: !Hll..!..ngs, ~ontana,
<br />dut'ing, the 1977 f: e.'_..! sca:::lon so tltat th~sc tiyscem:::l
<br />can be investigaced I.:e.r~_it.::r in t!lc:!..r 11ft.:: cycle.
<br />
<br />6.
<br />
<br />~FER.E~C'~S
<br />
<br />Ackerman, G., G. Achtcrneier, H. Appleman, S. Chang-
<br />non, F. Huff, G. :-!organ, ? SchlckeJanz and
<br />R. Semonin, .'...,)7(,: Design of the HigtI Plains
<br />Experiment W_LUl specific focus on p!l;~::lt!' 2,
<br />single cloul! experiment.:ltion. Fln~2.!E.
<br />on EIPL!::X nt>si\~', !lro-;ect to Division of
<br />Atml.lspheric ~\'~!LI..'r Retiources ~..unagemcnt, Bureau
<br />of Rec:!.amut1ul\, ~3~ pp.
<br />
<br />Eddy. A., 1975: Hain gage networ~-< analysis:
<br />Report; 1 to t!u:: Division of At!!1ospherJ.c ''':ater
<br />Resources Y;allagl~!T1ent, BUrl.!ilU of Reclilma-t'!.on
<br />Contract 014-060-9-7633.
<br />
<br />_______, 1976: Rain ~a~e net~or~ analysis. Pinal
<br />. Report to th~ B~r;,'u of !{eclumation, Division
<br />of Atrnogph~t'ic ~..:llter Resources ~anagement,
<br />Contract #14-060-0-7633, 3i pp.
<br />
<br />Cabriel, K., 1967: The Israeli artificial raInfall
<br />stimulation ex?crlm~ne. Statlsticul evalua-
<br />tion for the period 1961-1965. ~lfth Berkeley
<br />Symposium on !o!athematics and StacistIcal Prob-
<br />ability, University of California Press 5,
<br />91-113,
<br />
<br />Hartzell, C., and R. Barnes, 1976: In-depth study
<br />of the occurrenc~ of convective cloud~ over
<br />south-central-southcast ~ontana ane. north
<br />cencral Wyoming. Rpt. CSP-849-48, 47 pp.
<br />
<br />Huff, F., 1969: Climatological assessment of
<br />natural precipitation characteristics for use
<br />in weather modification. J. ADD1. Met. ~,
<br />1,01-410 .
<br />
<br />_______, 1970: Rainfall evaluation studies. Final
<br />report to National Science Foundation, Atmos-
<br />pheric Sciences Section NSFCA-1360, 53 pp.
<br />
<br />_______, and S. Changnon, 1972: Evaluation of
<br />potential effects of weather modification on
<br />agriculture in nUnois. J. Appl. MeC, 11,
<br />376-381..
<br />
<br />Maddox, R., and D. Reynolds, 1976: ^ satellite
<br />climatology of convective clouds and cloud
<br />systems over eastern ~ontana anc Wyoming.
<br />Special report to the BuriCau of Reclamation,
<br />21 pp.
<br />
<br />Woodley, W., J. Simpson, R. Blondini and J. Berkeley,
<br />1977: Rainfall results, 1970-1975: Florida
<br />Area Cumulus ExperIment. ~ l2i (4280),
<br />735-742. -
<br />
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