2013-04-4 MISC: CA

[R R Smith]

Tornado warning (public reported) just expired in northern California (Tehema County). Actually a decent set-up for CA low topped super cells and tornados - post frontal (actually post wave) thunderstorm, 40 kn SW @500 mb, surface winds SSE @ 10 gusting to 20 at Red Bluff, 55 dew, 300 CAPE. Missed it!

Here are the GR level 3 Grabs:

 

[David Biggar]

It was funny watching the models argue this AM...RUC had CAPE of 60, RAP had CAPE of 450 (for KSAC).

We never got out of the post frontal soup which inhibited any convective activity, but it looks like a small dry slot seen on H2O vap slid in over the north end of the state providing just enough clearing. After everything happened I checked the RAP for Red Bluff and got CAPE values around 900 near 6PM. 0-6km/0-1km shear was within the range that the STO office's "any EF0" based on previous cases. Had the soup cleared this AM with the passage of the front, the whole valley would have seen some sort of action.

Additional support came from a boundary that moved from west to east across the valley, provided some convergence, or at least just enough to get everything moving. There was a nice line of storms that developed (and are still going 3 hours later as I write this post) right along this line. CANSAC Image

Storm showed rotation for a good amount of time before SVR warning was put out (for hail). Hook shape quickly followed, and TOR warning came with media report of funnel cloud. By California standards, the rotation signature from BBX's velocity scans were very impressive, up there with the outbreak from a few months ago.

So far, LSRs report 1 tornado, NWS has not yet sent out a team to evaluate damage, but they have contacted several eyewitnesses. Duration of the tornado was 2 min.

We have a pic and video that can be seen here: http://on.kcra.com/16AAPq9
Other pictures can be found from the Chico TV station KRCR-TV (ABC 7).

 

[R R Smith]

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE SACRAMENTO CA
1117 AM PDT FRI APR 5 2013


...TORNADO IN TEHAMA COUNTY THURSDAY EVENING SOUTH OF RED BLUFF...


DATE: APRIL 4, 2013



TIME: 659 PM LOCAL TIME



LOCATION: 2 MILES SE RED BLUFF CALIFORNIA, TEHAMA COUNTY



EVENT: TORNADO...REPORTED BY PUBLIC AND TELEVISION STATIONS
A BRIEF ROPE TORNADO WITH VISIBLE DEBRIS CLOUD IN
AN EMPTY FIELD SOUTH OF SHASTA COLLEGE.
TORNADO DURATION 2 MINUTES. SEVERAL PHOTOS TAKEN.
MINIMAL DAMAGE REPORTED DUE TO OPEN FIELDS IN
VICINITY OF TORNADO.


RATING: EF0 65-85 MPH



ANY QUESTIONS OR COMMENTS CALL THE NATIONAL WEATHER SERVICE IN SACRAMENTO
AT 916-979-3051.