A low pressure system spread moisture into Merced County and into Yosemite Park on on the evening of February 9. This system moved southward on the morning of the 10th spreading heavy precipitation across the Yosemite Park area, the Mariposa County foothills and the rural areas of Merced County to the southeast of Merced.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS HNX wrote it up.
A low pressure system spread moisture into Merced County and into Yosemite Park on on the evening of February 9. This system moved southward on the morning of the 10th spreading heavy precipitation across the Yosemite Park area, the Mariposa County foothills and the rural areas of Merced County to the southeast of Merced. Some thunderstorms broke out that afternoon bringing additional heavy rainfall to the central San Joaquin Valley. Snow levels were around 8000 feet on the 10th lowering to around 6500 feet in Yosemite Park on the afternoon of the 11th in a cooler and showery airmass.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Hanford, CA wrote its last area forecast discussion before the first event at Feb 9, 3:02 AM PST, 4 hours 43 minutes earlier.
Area Forecast Discussion National Weather Service San Joaquin Valley - Hanford CA 302 AM PST Thu Feb 9 2017 .SYNOPSIS... The next Pacific storm system will move into the area later today and persist through early Saturday. Heavy rain and high elevation snow will affect the mountains with rain for lower elevations. Dry conditions will return by Sunday and persist through the middle of next week as high pressure builds over the region. && .DISCUSSION...Extremely warm and moist airmass in place over the region. Soundings from Vandenberg and Oakland had freezing levels at 12700 and 10200 feet respectively and the flow into the West Coast remains from a warm southwesterly direction. Water Vapor imagery shows the next fetch of deep moisture now moving into the Bay Area as the ridge over California and Nevada is being nudged to the east. Latest radar trends show orographic light precipitation now beginning over the Sierra as the deep moisture is lifted and dropped as rain and very high elevation snow. Latest High Resolution Rapid Refresh (HRRR) model increases the intensity of the orographic precipitation throughout the morning and by mid afternoon brings the incoming dynamics driven enhanced precipitation band into Merced County and then drives it southeast through the evening and into Kern County overnight. All the while the southwest to west flow aloft will maximize orographic enhanced precipitation over the Sierra, foothills and Greenhorn Mountains of Kern County. Flooding will undoubtedly occur again over parts of the area as saturation is just an understatement of the antecedent conditions and an areal flood watch is in place for all but the Kern County Desert areas where downsloping will keep any rainfall light. Main stem rivers such as the Merced and San Joaquin continue to be in flood or near flood levels from previous deluges and the forecast of an additional 2.5 to 4.5 inches of rain will certainly add fuel to the fire hose. Most, if not all creeks, streams, and other water ways are running fast or near flood and this latest precipitation event has the potential to cause some more major flooding issues. Okay, now how about the rest of the forecast. Models bring a closed low pressure center down the coast Friday night and Saturday and this will usher in cooler air and lower snow levels. This will occur as the main precipitation episode is waning however instability will continue to set the stage for showers and and just maybe some thunderstorm to develop on Saturday. All precipitation comes to an end by Saturday night as the low moves east and high pressure builds over the area Sunday through mid week. With the very saturated soil and copius amounts of standing water, fog will likely become a problem over the San Joaquin Valley through Wednesday. Oh, just in case you were wondering, yes indeed the next storm system is progged to arrive on Thursday of next week. && .AVIATION... In the southern Sierra Nevada and adjacent foothills, areas of mountain obscuring IFR in low clouds and precipitation, becoming widespread IFR spreading north to south after 21Z. In the Tehachapi Mountains, areas of MVFR and local mountain obscuring IFR in low clouds, becoming IFR in precipitation after 06Z Fri. In the San Joaquin Valley, areas of MVFR and local IFR visibility in mist until 18Z Thurs. Areas MVFR and local IFR in precipitation spreading north to south after 21Z. Elsewhere, VFR conditions will prevail for the next 24 hours. && .AIR QUALITY ISSUES... None. && .CERTAINTY... The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit www.weather.gov/hnx/certainty.php for additional information an/or to provide feedback. && .HNX Watches/Warnings/Advisories... Flood Watch from this evening through Friday evening CAZ089>097. && public...Dudley avn/fw...DCH synopsis...Dudley weather.gov/hanford
The San Joaquin Valley radar (KHNX), 129 km away, was scanning. The volume nearest the first event began at 15:46 UTC.
7 flood, 4 debris flow, 2 flash flood, 1 heavy rain, 1 heavy snow. Local standard time, as filed.
Trained Spotter near Ponderosa Basin in Mariposa County reported a 24 hour rainfall total of 1.66 inches. Also reported a season total of 55.56 inches.
California Highway Patrol reported a rock slide due to heavy rainfall on Highway 140 east of Ferguson Bridge about 5 miles north northwest of Midpines.
COOP station at Tuolumne Meadows reported a measured 24 hour snowfall of 12 inches in Tuolumne County at an elevation of 8,694 feet. Also reported a snow depth of 126 inches.
California Highway Patrol reported both lanes on Highway 140 near North Cunningham Road were affected from moderate to heavy rain for the previous 2 to 3 hours.
California Highway Patrol reported one lane partially blocked due to debris on Highway 140 near Mt. Bullion Cut Off Road.
California Highway Patrol reported a stranded vehicle on Guadalupe Creek Road near Yaqui Gulch Road with 100 feet of flood water running on both sides.
California Highway Patrol reported large boulders in the roadway on both lanes of Highway 140 near Bug Hostle and Octagon southeast of Briceburg.
California Highway Patrol reported a vehicle stuck in large amount of water and mud on Cunningham Road near Santa Fe Avenue in LeGrand.
California Highway Patrol reported roadway flooding on Road 26 at Avenue 17 in Madera Acres.
Mariposa Dam reached capacity and was being over-topped. Army Corps of Engineers was releasing water down the emergency spillway.
California Highway Patrol reported roadway flooding on White Rock Road northeast of LeGrand.
County emergency manager reported flooding in eastern Le Grand due to Mariposa Dam over topping its emergency spillway.
California Highway Patrol reported 5 to 6 football sized rocks in the southbound lane of Interstate 5 near Lebec.
California Highway Patrol reported a debris flow blocking both lanes on east Trimmer Springs Road near Piedra Road in Piedra.
California Highway Patrol reported large boulders blocking westbound lanes from heavy rainfall of Highway 33 near Soda Lake Road about 13 miles south of Taft.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2017Every state in 2017This day in weather historyWarnings in California, February 2017
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 682697, 682700, 682698, 682684, 682685, 682686, 682687, 682688, 682693, 682683, 682694, 684608, 682702, 682704, 682705.