December 11-12, 1995
West Coast Mega-Storm
Jan Null, CCM 1
Dr. John Monteverdi, CCM
By the Numbers
- #1 All-Time on Bay Area Storm Index (BASI)
- 103 mph gust at Angel Island
- 134 mph gust at Kregor Pk
- 1000 trees blown down in Golden Gate Park
- $15M damage to SF Arboretum
- Power Out to 1 million PG&E Customer

 & Data

- Bay Area Storm Index
 - U Wash Storm Summary for West Coast
SFSU "West Coast Bomb" Case Study

NWS Storm Data - Dec 1995
- NWS Hourly Precip - Dec 1995

  San Francisco Chronicle, Dec 13. 1995

24-hour Surface Analysis (00Z Dec 12, 1995 to 00Z Dec 13, 1995)
Wind and Rainfall Summaries
December 12, 1995 Reanalysis
500 mb Height

Composite 500 mb height pattern for the 24 hours centering on 12 UTC 12/12/95.  The axis of a strong “breakthrough” jet was oriented over the Bay Area.  This kept favorable lifting mechanisms phased with topographic effects in north-central California.

500 mb Height Anomalies

Midtropospheric flow was kept unusually strong by below normal heights in the Gulf of Alaska and above normal heights over the Southwest.

Mean Precipitable Water
A strong surge of subtropical moisture associated with what is now known as an Atmospheric River was phased over the area for more than 24 hours.  The magnitude of the precipitable water values (cm) were near record for December.  Precipitable water is a measure of the amount of rainfall that would occur if all the water vapor in the atmospheric columns were converted to precipitation by lifting mechanisms.  The moisture advection (transport) associated with this event would categorize it today as in the strongest category of Atmospheric River Events.
Precipitable Water Anomalies
The unusually strong Atmospheric River transported the precipitable water to the coast in such quantity that the anomalies were at the highest end of the scale.

1 Adjunct Professor of Meteorology, San Jose State University
2 Emeritus Professor of Meteorology, San Francisco State University
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