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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3c. Seedability

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Althcug~ ttese cloUGS routinely contained subs:antial amounts of

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su~ercooled liquic ~ater near their upwind edges, it ~as not possible to

cond~ct ~eeding expericents in thew. for two reasons.

First, SCpp

s~s!e~siOD criteria specifically precluded conducting seeding experiments
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d~ring observed o~'predicted severe weather such as hail.

Secondly, the

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lightnir:g

styikes to the King Air precluded flights in

these

stor:ns.

T~e fact that the cloud downwind of the deep convection was

:o~a~lv glaciated indicates that seeding these storms would only result in

a redistributio~ at precipitation.

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During the 10 field seasons no more than one classic cold front per

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season was observed to pass over the area. A classic cold front is one

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describec by the Korwegiar. frontal theory. The classic cold front consists

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c: a disti~c:, tilted typerbaroclinic zone throughout the troposphere,

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~~S~ia:s a cistir.ct polar front jet above the hyperbaroclinic zone and

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oe"eath the tropopa~se, displays backing with height behind the cold front

which ir.plies cold air advection and displays veering with time during

f~Q~tc~ passage.

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Ccrbcne (1982) has presented daal-Doppler radar data on one of these

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rare (for California) classic cold fronts.

His cold front did display a

char~c~er~stic which had not bee~ p~eviously observe~.

The cold front at

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