San Francisco Snow? (Would Be) Fifth Occurrence in Last Century Update: No SFO Snow, 1976 Record Holds

Feb. 28 Update: Other than a few flurries, snow failed to materialize in San Francisco. The National Weather Service reports:

As it turns out, a few showers did linger during the early morning hours of February 26th to allow for snow all the way down to sea level. However, only trace snowfall was reported around San Francisco. Therefore the last measurable snowfall in San Francisco still remains 1976. Farther south toward Monterey, light snowfall dustings were also reported. Higher peaks above approximately 2000 feet received more measurable snowfall with a few inches, which is not unusual for this time of year. The overall airmass remained rather unstable during the afternoon of February 26th which resulted in convective rain and snow showers across the region. Several weather spotters reported snow down to sea level once again, but no accumulation was noted.

1:30 PM PST Update: (Headline modified to clarify event is only a possibility.) The latest forecast discussion from the National Weather Service confirms that measurable snow is unlikely below elevations of 500 feet:

 AFTER THE FRONT MOVES THROUGH THE RAIN WILL TURN TO SHOWERS. THE NORTH BAY
 MOUNTAINS COULD GET SEVERAL INCHES OF SNOW LATER THIS MORNING INTO
 THE AFTERNOON...BUT THE MAJORITY OF THE PRECIPITATION WILL END BY
 LATE AFTERNOON NORTH OF THE GOLDEN GATE. THERE COULD BE LIGHT
 RAIN/SNOW SHOWERS TONIGHT...WITH SAN FRANCISCO POSSIBLY SEEING SOME
 SNOWFLAKES OVERNIGHT...BUT NO ACCUMULATION IS EXPECTED. LOOKS LIKE
 THE MAIN AREA THAT HAS THE BEST CHANCE OF SEEING SIGNIFICANT SNOW
 WILL BE THE SANTA CRUZ MOUNTAINS AND THE EAST BAY HILLS SOUTH...AND
 SOUTH OF THE SANTA CLARA VALLEY IN THE LOWER ELEVATIONS. 

Note to Ice Agers: The average change in temperature with height is 5.38°F/1,000 Ft, more when the air is especially cold aloft as in the current situation, so snowfall in the hills doesn't count for any records.

Meanwhile, very heavy rainfall rates have been reported this morning from the storm. A downpour in northeastern San Francisco recorded 0.11" of rain in 5 minutes, a rate of over 1" per hour. Over 2" were reported in 24 hours west of Cupertino.

Original post:
A strong upper-level low pressure area is bringing cold temperatures to the San Francisco Bay area and prompting the National Weather Service to issue a winter weather advisory for elevations above 1000 feet in the North Bay area:

A WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 4 PM PST
 FRIDAY. 
 
 * SNOW ACCUMULATIONS: 1 INCH 1000 TO 1500 FEET WITH 2 TO 4 INCHES
   ABOVE 1500 FEET. 6 INCHES OR MORE FOR ELEVATIONS ABOVE 2500 FEET.
 
 * ELEVATION: HEAVIEST SNOW WILL BE ABOVE 1500 FEET BUT
   ACCUMULATING SNOW IS EXPECTED AS LOW AS 1000 FEET.
 
 * TIMING: A MIX OF RAIN AND SNOW WILL CONTINUE THIS EVENING AND
   CHANGE TO ALL SNOW OVERNIGHT AS SNOW LEVELS DROP. STEADY PRECIPITATION
   WILL CHANGE TO SNOW SHOWERS BY FRIDAY MORNING.  

If measurable snow were to occur at sea level, it would be only the 5th such occurrence in the past century, according to Golden Gate Weather Services. Unofficial reports indicate that there were 7 such events in the second half of the 19th century.

H/T: NCAR AtmosNews