# Presentation: 070497

- It’s always sunny and 72 in San Diego, right?

- Jim Purpura
- Meteorologist-In-Charge
- WFO SGX

## February 19, 2005

- Long lived (5+ hours) supercell began in Mexican coastal waters
- Produced at least two tornadoes
- This is not a waterspout (note RFD notch) but a supercellular tornado over the Pacific

- Tornado off Huntington Beach  2/19/05
- 7:38 a.m.

- © Dave Chapman

## FEBRUARY 19, 2005STORM DATA

## So...how did we do?

- Not very well!
- Situational Awareness Poor
- Staff not aware of 4:53 am PST MCD discussing tornado potential
- Skywarn not activated, no spotters out
- Staff used Composite Reflectivity, not 4 panel
- Often used in complex terrain due to blockage factors
- Severe Thunderstorm Warning Issued, then changed to Tornado Warning
- Based on MIC’s view of radar at home and visual spotting of wall cloud and developing RFD

**MESOSCALE DISCUSSION 0169 **
**NWS STORM PREDICTION CENTER NORMAN OK 0653 AM CST SAT FEB 19 2005**
**AREAS AFFECTED...L.A. BASIN AREA OF SRN CA CONCERNING...SEVERE **
**THUNDERSTORM POTENTIAL VALID 191253Z - 191500Z ENVIRONMENT IS ****BECOMING **
**MORE FAVORABLE FOR SEVERE FROM CONVECTION THAT CONTINUES TO FORM **
**INVOF ERN CHANNEL ISLANDS AND MOVE ASHORE COASTAL LOS ANGELES COUNTY****.**
**EXPECT THREAT TO SHIFT GRADUALLY EWD ACROSS ORANGE...SERN L.A. AND **
**EXTREME NWRN SAN DIEGO COUNTIES THROUGH NEXT FEW HOURS****. OCCASIONAL **
**DAMAGING WIND AND MARGINALLY SEVERE HAIL REMAIN POSSIBLE IN ASSOCIATION **
**WITH MINI-SUPERCELLS AND BOWS...AND ****BRIEF TORNADO CANNOT BE RULED OUT****.**
**MOISTURE CHANNEL IMAGERY INDICATES SMALL MID/UPPER LEVEL VORTICITY **
**CENTER LOCATED OVER PACIFIC APPROXIMATELY 100 SW LAX AS OF 1230Z. **
**AS THIS FEATURE APCHS...LOW-MIDLEVEL GRADIENT FLOW IS STRENGTHENING **
**ACROSS REGION PER VWP TRENDS...INCREASING DEEP-LAYER SHEAR. BOUNDARY**
**LAYER RESPONSE HAS ENLARGED 0-1 AND 0-3 KM HODOGRAPHS ALSO.**
**EXPECT 75-125 J/KG SRH THROUGH 0-1 KM AGL LAYER TO BE MAINTAINED UNTIL VORT LOBE **
**MOVES ASHORE AT APPROXIMATELY 15Z. LAPSE RATES SHOULD STEEPEN SLIGHTLY IN**
**MIDLEVELS AS WELL...YIELDING MUCAPES UP TO 400 J/KG...BASED ON MODIFIED RUC**
**SOUNDINGS. ****STORM SCALE ROTATION ALREADY APPARENT WITH CELLS NEAR **
**ERN CATALINA AND SAN CLEMENTE ISLANDS MAY INTENSIFY BECAUSE OF FRICTIONAL**
**CONVERGENCE  EFFECTS AS THEY MOVE INLAND...AND ADDITIONAL CONVECTION DEVELOPING**
**FARTHER S MAY FOLLOW SIMILAR MORPHOLOGY AS WELL AS ENTIRE**** ****REGIME SHIFTS EWD****.**
**...EDWARDS..**
** ****02/19/2005 ATTN...WFO...SGX...LOX... **

## MCD issued at 4:53 am had it right...

## KNKX OBSERVED SOUNDING, 1200Z 02/19/2005 

## KNKX 4-PANEL SRM2-19-2005 17:20 GMT

## KNKX 4-PANEL REF2-19-2005 17:20 GMT

## Supercell was on radar for 5 1⁄2 hours! (1245Z-1820Z)

## Why is this important? Tornadoes rarely occur in southern California, right?

## “Tornado frequency per unit area per time in the Los Angeles Basin is higher than the state of Oklahoma.”

- A quote from Jack Hales (presentation to SGX staff 12/05) His data...
**In the ****Los Angeles Basin****, for the period of 1950-1992, there were 3.19x10****-4 ****tornadoes km****-2****yr****-1****.**
**In the ****state of Oklahoma****, there were 2.86x10****-4 ****tornadoes km****-2****yr****-1 ****for the same period. **
**A high end EF-2 or low end EF-3 is probably the maximum possible, based on records **

## Population in southern California is Huge

- LOX CWA ~ 12,000,000 population
- SGX CWA ~ 10,000,000 population
- Together this merging metro area has ~ 7% of the population of the US
- Benign weather mentality makes preparation for low probability, high impact events extremely difficult

## So...what have we done to avoid this next time?

- This was made into a WES case
- Required for all ops staff.
- MCD product set to alarm when “SGX” mentioned in text string.
- We brought Jack Hales to the office to talk about southern California tornadoes.
- Jack was uniquely familiar with local challenges.
- Jack lived in southern California.
- Worked to decrease dependence on algorithms and Composite Reflectivity vs. base data.
- Still a struggle. In most situations Composite Reflectivity works well. Forecasters gravitate to it.

## Some thoughts...

- After years of working with the staff on these extremely rare events, it’s probably not possible to get them all to a “Plains level” of Situational Awareness for Severe Weather.
- We do have a cadre of 6 good severe weather (warning) forecasters.
- We try to anticipate an event and make sure one of the cadre is available.

## Final Thoughts...

- We need a bit more help from SPC than Midwest or Plains offices in recognizing these events
- Random probably of an event is low but large population may potentially be at risk.
- Rare nature of events mean few forecasters will be true severe weather “experts”
- Pattern recognition is getting better, but still needs to improve.
- SPC – please ***call us*** if we don’t seem to “get it”!

## Questions?

- Thanks to Jack Hales for some of the slides from his 12/05 presentation at SGX
- Tornado picture from Dave Chapman at _www.stormdude.com_