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

.~

-~ .
-..;ti.. "

presen~ near 1 k~.

. ..

The wind vector a~ 1 km was oriented

'\400 upslope.

i
:'j
~I
I
I
i
:1
..
,

--
i:i~.

~~~S ~es an u~usua::y ~~sta~!e situation.

ihe hodograph or the VAD

~erived winds at IJJf LSI is presen:ec in Figure 9. A weak barrier jet was

~~e L c~c ~ ~i~d co~po;.e~:s are plotted separately ~n Fig~re 10. The

narrler jet is apparent in the V-co~ponen:

\o;~th an 18 m

-1 .' ..r
S wlnd speeu

at

~1.3 k~ 21ti~ude.

The'~surface frictional effect is a?pare:1t ir.. both the U

i
"j
-!

an~ \ compone~ts beio~ the LLJ.

trow. 1.5 to ~.O k~ the U-component is

unifor~. whi~e the V-cc~ponent cecreases with altitude. Above 4 km the U-

co~ponenL is highly shearec wl:h ~he altitude of the wind shear suggesting

that tte wi~ds might na~e beer.. b:ccked by tte convect~ve clo~ds in this

case ra:her than by the ~arrier as ir. the previous case.

The profile ot

the V-co~ponent suggests that blocking by the convective clouds may have

induced the "barrier" jet.

3:. Precipitation processes

Figure 11 is the PPI reflectivity at 30 elevation and at 1556 LST. The

reflectivities begir.. at 30 dBZ and are contoured at 10 dB intervals. A

~~~2 of severe thunderstocms ~ith peak reflectivities of 40-60 dBZ are

p~esent ~20 kc downwinc of the radar and parallel to the crest. The severe

thur..derstor~s are 25 K~ apart.

An RHI scan was taken across the Sierra

~arrier along the 07Q~ rad~al a~ 1550 LST with the CP-3 Doppler radar. The

re:lectivi~y a~d airflo~ cross-sections are shown in Figure 12. A bright

~cnd W2S net prese~t a~d echoes were nearly erect.

~ese are typical

e~nces ~rG~ ca~vective cicuds.

The reflectivity cross-section (Figure 12)

s~o~s ~~o LQ dBZ ec~oes at 30 and 40 km range.

The echo at 30 km range

co,-ta~nec reflectivity ot 50 dEZ i~ the lc~est kilo~eter.

The 40 dBZ echo

28