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1997-98 Rainyear in Review 

1997-98, was a year marked by perhaps the strongest El Nino event in recorded history. While the peak ENSO index failed to reach the peak set in 82-83, this El Nino had two distinct peaks, first around Aug97 and the other around Feb98. Due to sheer longetivity  of peak/near peak conditions, rainfall was above normal for most of the season. While El Nino was evolving months earlier in the tropics, the local effects of El Nino began abruptly in July, as heavy south winds to 40mph for almost three days pulled 70+F water up the coast. Thousands of seals, porpoises, dolphins and other mammals together in gigantic packs were seen from SF to Half Moon Bay feeding on sardine and makarrel for over a week after the warm south winds blew through and just ahead of the warmer water. The sight of these animals, all jumping and in near frenzy just outside the breaker line had never been seen before. Record  and near-record rains fell over Cent. Cal. in August from remnants of five consecutive tropical depressions, and hindsite now suggests (as did I at the time) that this track may have set the tone for the bulk of the El Nino rainy season. Heavy rains fell also in October and November, then tapered off in December (which was the only below average month for the year). By January '98, rains became near monsoonal as storm after storm pummeled the West Coast with rain and high winds. Traning storms across the Pacific created near constant pounding surf which frequently hit 20'over widespread coastal areas and over 30' in localized spots.  On at least three occasions, the Pacifica Pier was closed for fear of public safety. Much erosion to cliffs in Pacifica occurred, and numerous homes along Esplanade Dr. were red tagged, then eventually demolished, where up to 30' of cliff was washed away. 10' erosions were common elsewhere. Despite the exceptional rains, landslides did not cause nearly as much damage as 1982, however many homes were threatened. The most significant landslide in the area was in Russian River area (Forestville), as an entire mountainside threatened to slide (but never did). Rainfall peaked in late Jan. through late Feb., with Feb. rains totaling almost 14", or an astounding daily average of 0.5" of rain AVERAGE for the entire month.  Rains in Jan. and Feb. alone amounted to almost 25", which exceeded our normal yearly average of 23". March and April also had near/slightly above normal rains, but lacked the intensity or frequency of the Jan/Feb rains. However in May, usually a dry month with only infrequent light rains, heavy, violent storms occurred. Three different Tornado events happened in the Bay Area, the most notable an F2 in the Sunnyvale area which did extensive damage to dozens of homes. The Tornado(s) also caused damage in Los Altos Hills, however it is not known if it was the same tornado to hit Sunnyvale or a separate funnel (although the timing and tracks would suggest a single funnel hopscotched SE to NW. The tornado, which was heavily video'd, revealed that this was a rare tornado with anti-cyclonic winds. Other funnels during the month were seen near SFO and another touchdown observed near Fairfield. By my count, we had 12 different days with T'storm activity in the area. Because of very cold air aloft pulled down by upper level lows anchoring off the coast, snow in the Bay Area hills was common, with 2.5K' to 3K' snow levels. Snow in the hills in May is virtually unheard of. Rain for the month was near 4" as compared to an average of around 0.25". with 15 days of rain, compared to only 2-3 which is normal. By June, rain in the early part of the month tapered off to zero by month's end, as El Nino finally retreated, and La Nina conditions starting to be noted in the Cent. Pacific. For the rainyear of 1997-98 rainfall at my house totaled 46.59" and the official NWS spotter station about 1 linear mile away, 55.25".  Elsewhere in Pacifica, such as Vallemar and the Pedro Valley Ranger Station, rain totals exceeded 60". Using these combined weather data, a consensus has been reached that this is the rainiest year on record in Pacifica.  Because of the lack of long period "official"  NWS data, and the high variability of rain just within Pacifica, caution had to be taken (climatologically speaking) not to base conclusions about rainfall on any single reporting station . '97-'98 easily eclipsed the earlier record in 1982-'83  when an estimated 51" fell.  Rainfall average at the Vallemar reporting station (where records go back 36 years - our longest single database) is 27" per year, putting this year around 230% of normal. Other noteworthy rain totals include 47.22" at San Francisco (making it the second wettest year ever - the record being 49.27" in 1861-62),  an unbelievable 153" (OVER 12 feet!) in the Central Sierra Nevada in the Feather River Canyon area, over 116" at Cazadero in northern Sonoma County, and 91" at Lake Lagunitas in Marin County. San Francisco's total as well as other stations in the area all were about 230% of normal, or the highest deviation from normal for any major city in California. On June 6, Fresno was hit with severe T'Storms, which dumped 1.8" in one day (which shattered the old monthly record for June). Snowfall at Norden in the Central Sierra, totalled 450", well shy of the record of 600" in 1982-'83. On average, this was only the fourth wettest rainyear in the Sierras on record.  Despite the record nature of El Nino's wrath in 97-98, damage while catastrophic in localized areas such as the Russian River area , Big Sur, and along the cliffs of Pacifica, was considerably lighter than in the La Nina influenced month of Jan-1997 when over $1 Billion in damage was done to vast areas of the Central Valley, Yosemite and elsewhere. While losses in 97-98 have yet to be totaled up, they should be well shy of 1997.

 

'97-'98 Rain by Month at My House in Pacifica

1997                                                              
 Jly      Aug      Sep       Oct         Nov      Dec
.04      1.20      .12       1.12       7.93     3.37

1998
 Jan 
     Feb      Mar    Apr      May     Jun
10.35     13.53    2.22    2.37     3.58    .25 
Total 46.59"