WMOD00300 ‎(2)‎

• Contract/Permit #: 2-07-81-V0256
• Title: Cloud Physics Studies in SCPP From 1977-87
• Date: 10/1/1987
• Weather Modification - Doc Type: Report

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Tho ~Q~n prer": -~ ~::::.t''': (";- r-"e tT;'l" C.l.....0 '!~) I-or "he> ~erl-d l~l U. ~O() T,.,rn
_u,- ".~c:..' ,--'-p~:",-_-,--.l." _CL. \1 O~L ~ .L.... '- ~ p . v. :;J~-ll u L~l is

D2se2 on r~O precipitatio~ gages in the SCPP.

The upwirrd edge tor the

r2i~fall ~as ~2a ~~ !ro~ ~~e CP-3 radar.

The meaD precipitation rate was

~ 1~
~ea~~y unifor~ froc 25 to 75 km ra~ge.

In the zo~e from 25 to 75 km. the

iastc~:aneo~s rai~fall ra~es from t~e convect~ve storms are much higher

than the cea~ ~recip~tatio~ rate.

The sterns formed along the convective

line ~ear '20 k~, .a~~ moved ~p the barrier as they precipitated. The

i~~egrated effect was to produce a uniform mean precipitation rate over the

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I
!
,

~idd:e part of the barrier.

Since the net effect from both this convective case and the previous

stable case was a unifo~m precipitation rate over much of the Sierra

barrier, it should not be surprising that the total annual precipitation

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over the upper half of the Sierra barrier is approximately uniform.

Flights through this and several other deep, unstable orographic storms

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t

G~ring the early years of sepp indicated that the upwind edges of these

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!-

cC:1vective

,.
_l.nes

were ice free and contained continental

dr,Qplet

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.-

!

~o~centratlons of

-3
200 to 4QO cm

As the convective clouds ascended

through the -15 to -20oC level, natural ice developed. In the presence or

liquid wa:er conte~ts approaching adiabatic values, the ice ?articles grew

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L:

rapicly by r~ming res~lting in lightning, graupel and small hail. Downwind

or the deeD cOGvection and over the upper half of the barrier, the cloud

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i-
F

was totally glaciated.

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io ~ -

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34