California, 2015

Drought in California, May 1 to 31, 2015

May 1 to 31, 2015 · NWS STO · 8 events in 8 counties and zones

The long term drought continues as May was yet another below normal month for precipitation for much of the area. There was some mountain precipitation in the form of rain, but much of it was focused along and east of the crest.

The toll

Deaths
0
Injuries
0
Property damage
None recorded
Crop damage
None recorded
Events
8

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.

What happened

The episode as NWS STO wrote it up.

The long term drought continues as May was yet another below normal month for precipitation for much of the area. There was some mountain precipitation in the form of rain, but much of it was focused along and east of the crest. Snow pack was at the lowest levels on record and by the end of the month was virtually nonexistent. As a result, reservoirs across the area by the end of the month were at well below normal levels and were already beginning to drop.

Extreme drought was detected by the U.S. Drought Monitor across most the region, with exceptional drought for the northern San Joaquin Valley, the central and southern Sacramento Valley, the Burney Basin and the Sierra south of Interstate 80.

Governor Jerry Brown declared a drought emergency for the entire state of California January 17, 2014 and this continued to be in effect.

As a result of continuing drought conditions, emergency legislation appropriated over $1 billion of additional funds for drought-related projects and activities.|The Administration’s May Revision proposal includes an additional $2.2 billion for programs that protect and expand local water supplies, improve water conservation, and provide immediate relief to impacted communities.

Local Emergency Proclamations have been issued for El Dorado, Glenn, Lake, Plumas, San Joaquin, Shasta, Sutter, Tuolumne, and Yuba counties. The cities of Live Oak Lodi, and Ripon continue in a drought emergency. Drought task forces have been established in Butte, Lake, Nevada, Placer, Plumas, Sacramento, San Joaquin, Stanislaus, Sutter, Tehama, Tuolumne, and Yolo counties to coordinate response to the drought.

Mandatory water reductions of 25 percent as ordered by Governor Brown were in effect statewide, the first time such mandatory restrictions have been enacted.

Agriculture has been heavily impacted, with numerous farm and farm related jobs lost. Spring planting is being scaled back significantly, with many existing tree crops and vines being removed due to a lack of irrigation water. The state continued to supply food assistance to those impacted. California Disaster Assistance Act money continued to be provided for those who have lost drinking water due to dry wells.

Construction was begun of a $40 million temporary drought barrier on the West False River in the Sacramento-San Joaquin Delta was started to keep tidal salt water from contaminating drinking water to Bay Area residents.

Additional impacts included low spring runoff on fisheries and ecological affects on forests and wildlife.

What forecasters said that day

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 Sacramento, CA wrote its last area forecast discussion before the first event at Apr 30, 7:54 PM PST, 4 hours 6 minutes earlier.

Area forecast discussion, Apr 30, 7:54 PM PST, 4 hours 6 minutes before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
854 PM PDT Thu Apr 30 2015

.Synopsis...
Warm and dry weather will continue. Above normal temperatures will
continue through the weekend despite a cooling trend over the
weekend. A weak trough will bring a chance of showers or
thunderstorms near the Sierra crest the next several days. Low
pressure will bring a chance of showers or thunderstorms mainly
over the mountains during the middle of next week.

&&

.Discussion...
Temperatures are slower to cool off tonight generally running
2 to 5 degrees warming this evening than last night. High pressure
will keep mainly clear skies through tomorrow. Temperatures should
warm into lower 90s again in the valley for Friday. Isolated
thunderstorms look possible once again in the Sierra...mainly
from around Tahoe southward.

On Saturday and Sunday there will be a very weak through off the
northwest coast that may interact with some moisture coming up
from the south. Models vary on extent of showers and
thunderstorms. Generally the models have some showers and
thunderstorms from around Lake Tahoe southward although the NAM
hints at possible isolated activity just north and east of Shasta
County for Saturday. Both the GFS and NAM indicate some showers
and thunderstorms just north and south of Shasta County for
Sunday. Temperatures should start to cool a little over Friday's
highs and for the most part bring temperatures back down into the
80s. The delta breeze should start to pick up Friday night to
help start the cooling trend.

.Extended Discussion (Monday through Thursday)

An upper level trough is expected to deepen over the west Coast
early to mid week next week. This will bring a cooling trend and some
instability for a threat of afternoon and evening thunderstorms
over the mountains. Onshore flow will help keep the Delta region
and adjacent locations about the same through mid week. The 12z
ECMWF is slower with this system bringing a low through Northern
California late Wednesday into early Thursday. This is different (wetter)
than the 00z run which was more progressive and had ridge from
Eastern Pacific building into NorCal mid week. There is low
confidence in the track and timing of this system so went with
slight chance over the mountains.

&&

.Aviation...

VFR conditions over interior Northern California for the next 24
hours except some cumulus development with possible isold
thunderstorms for local MVFR/IFR conditions over the Sierra
around Lake Tahoe and south 20Z-04z Friday afternoon and evening.

&&

.STO Watches/Warnings/Advisories...
None.
&&

Event by event

8 drought. Local standard time, as filed.

Drought, Carquinez Strait and Delta

When
May 1, 12:00 AM PST to May 31, 11:59 PM PST
Where
Carquinez Strait and Delta forecast zone
Reported by
Newspaper

Construction of a $40 million temporary drought barrier on the West False River in the Sacramento-San Joaquin Delta was started to keep tidal salt water from contaminating drinking water to Bay Area residents.

The State Water Resources Control Board approved a program that allowed riparian water right holders in the Delta to voluntarily cut back water use by 25% in exchange for assurances they would not face deeper curtailments during the June-September growing season.

Drought, Northern San Joaquin Valley

When
May 1, 12:00 AM PST to May 31, 11:59 PM PST
Where
Northern San Joaquin Valley forecast zone
Reported by
Newspaper

Agriculture continued to be impacted with reduced planting and harvest of spring crops, bringing a significant loss of jobs. Tree mortality across the Valley increased, including even normally drought resistant oak trees. Golf courses faced pressure to use less water and were doing so, dry, brown appearance of the turf. Some golf courses shut down for lack of water. Many people reduced landscape watering at homes or removed grass lawns.

Drought, Southern Sacramento Valley

When
May 1, 12:00 AM PST to May 31, 11:59 PM PST
Where
Southern Sacramento Valley forecast zone
Reported by
Newspaper

Agriculture continued to be impacted with reduced planting and harvest of spring crops, bringing a significant loss of jobs. Tree mortality across the Valley increased, including even normally drought resistant oak trees. Golf courses faced pressure to use less water and were doing so, dry, brown appearance of the turf. Some golf courses shut down for lack of water. Many people reduced landscape watering at homes or removed grass lawns.

Drought, Northern Sacramento Valley

When
May 1, 12:00 AM PST to May 31, 11:59 PM PST
Where
Northern Sacramento Valley forecast zone
Reported by
Newspaper

Agriculture continued to be impacted with reduced planting and harvest of spring crops, bringing a significant loss of jobs. Tree mortality across the Valley increased, including even normally drought resistant oak trees. Golf courses faced pressure to use less water and were doing so, dry, brown appearance of the turf. Some golf courses shut down for lack of water. Many people reduced landscape watering at homes or removed grass lawns.

Drought, West Slope Northern Sierra Nevada

When
May 1, 12:00 AM PST to May 31, 11:59 PM PST
Where
West Slope Northern Sierra Nevada forecast zone
Reported by
Newspaper

Snow pack levels in the Northern Sierra for May were only about 1 percent of normal. Mountain reservoirs were below normal levels as a result, reducing water supply for to larger reservoirs and reducing hydro-electrical power generating potential.

Drought, Shasta Lake/North Shasta County

When
May 1, 12:00 AM PST to May 31, 11:59 PM PST
Where
Shasta Lake/North Shasta County forecast zone
Reported by
State Official

Snow pack levels in the southern Cascades for May were only a small fraction of normal. Lake Shasta and other area reservoirs were well below normal levels as a result, reducing water supply and reducing hydro-electrical power generating potential.

Drought, Mountains Southwest Shasta County to Northern Lake County

When
May 1, 12:00 AM PST to May 31, 11:59 PM PST
Where
Mountains Southwest Shasta County to Northern Lake County forecast zone
Reported by
Newspaper

The drought continues to impact Lake County, with farmers clipping some wine grape vines, reducing irrigation needed this summer, while also reducing their harvest. Agriculture and related businesses have continued to lose jobs.

Drought, Clear Lake/Southern Lake County

When
May 1, 12:00 AM PST to May 31, 11:59 PM PST
Where
Clear Lake/Southern Lake County forecast zone
Reported by
Newspaper

The drought continues to impact Lake County, with farmers clipping some wine grape vines, reducing irrigation needed this summer, while also reducing their harvest. Agriculture and related businesses have continued to lose jobs.

What these are

Drought
A drought reaching severe (D2) or worse on the US Drought Monitor, or with notable impacts.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

More

Every storm in California in 2015Every state in 2015This day in weather historyWarnings in California, May 2015

Sources

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: 568217, 581881, 581884, 581885, 581893, 581901, 581903, 581904.