1980 Jan and Feb events

This series of heavy rainfall events produced significant flooding in Central and Southern California which killed 18 people.   The worst flooding was and occurred in February as a second series of storms impacted south of San Franscisco.  Heavy rain and unusually warm temperature that led to snow melt helped produce significant flooding along the Carson River Valley in California and Nevada.

The synoptic pattern during this event shared many characteristics with other major flood events.  A positive height anomaly was present west of Alaska at 500h and to the southeast of this ridge a strong negative height anomaly was present (see below).  Another positive anomaly was present to its south leading to a stronger than normal gradient.  The event was associated with an atmospheric river that helped pull anomalously warm air north and eastward.  Note the above normal 850 temps of greater than 3  sigma off the California coast at 1200 UTC 12 Jan 1980. 

Large area 4-panel chart,  200-hPa heights and isotachs (top left), 500-hPa heights and normalized height anomaly (top right), 850-hPa heights and normalized temperature anomaly (bottom left), and 1000-hPa height and normalized PW anomaly (bottom right) valid 1200 UTC 12 Jan 1980 (top 4-panel) and valid 0000 UTC 14 Jan 1980 (bottom 4-panel).  The magnitude of the normalized anomalies are given by the color fill with the scale on the left had side of each panel.

PW (mm) and normalized PW anomaly (magnitude of the anomaly scale is shown on the scale at the bottom of the figure)  valid 1200 UTC 12 Jan. 1980 (top panel), 0000 UTC 13 Jan. 1980 (middle panel), and 0600 UTC 13 Jan 1980 (bottom panel).

850-hPa winds (standard barbs and flags) and normalized anomaly of 850-hPa moisture flux (magnitude is given by the color fill from the bar at the bottom of the figure)  valid 1200 UTC 12 Jan. 1980 (top panel), 0000 UTC 13 Jan. 1980 (middle panel), and 0600 UTC 13 Jan 1980 (bottom panel).

A strong atmospheric river was present with normalized PW anomalies that for awhile exceeded 4 standard deviations.  The river also produced an extended period with anomalously high 850 moisture flux with the normalized anomalies exceeding 4s.  

The second series of heavy rainfall events in 1980 occurred in southern California from a series of rainstorms that occurred  February 12-18.  There was again anomalously high heights over Alaska, below normal heights off the California coast with a second area of above normal heights south of the negative height anomaly (see figure below).  The pattern tapped into a strong atmospheric river with anomalously high PW and MF (not shown).  The series of February storms produced over 36 inches of rain at Mount Wilson Observatory (see figure at the bottom of the page). Over 18 people were killed from floods, flash floods and mudslides in southern California and Central Arizona. 

Large area 4-panel chart,  200-hPa heights and isotachs (top left), 500-hPa heights and normalized height anomaly (top right), 850-hPa heights and normalized temperature anomaly (bottom left), and 1000-hPa height and normalized PW anomaly (bottom right) valid 1200 UTC 16 Feb. 1980 (top 4-panel) and valid 0000 UTC 14 Jan 1980 (bottom 4-panel).  The magnitude of the normalized anomalies are given by the color fill with the scale on the left had side of each panel.

Heaviest 3-day rainfall analysis using the CDC .25 deg by .25 deg unified data set ending 1200 UCT 14 Jan 1980. 

24 hr QPE rainfall analysis using the CDC .25 deg by .25 deg unified data set ending 1200 UCT 12 Jan 1980. 

24 hr QPE rainfall analysis using the CDC .25 deg by .25 deg unified data set ending 1200 UCT 13 Jan 1980.