July 2, 2013 (updated July 9)

Highlights

    • Severe to exceptional drought conditions have gained more ground in our region after a dry June; significant drought impacts will continue.
    • June precipitation was below average over nearly all of the region except for northeastern Wyoming and portions of southeastern Colorado; most of Utah received no precipitation for the month.
    • Observed runoff from April through June was generally well below average across the region.
    • Region-wide, reservoir storage at the end of June was lower than at this time last year, and below the long-term average.
    • The NOAA CPC seasonal climate outlooks show equal chances for wet or dry conditions over the next several months, except in a few small areas.

 

Note: Special WWA-NIDIS drought briefing available On June 26, WWA and the National Integrated Drought Information System (NIDIS) released a two-page Summer 2013 Drought Summary and Outlook for Colorado, Utah, Wyoming, and New Mexico. This briefing summarizes recent precipitation, current and expected drought conditions, spring-summer streamflows, reservoir levels, agricultural impacts, and wildfire risk.

 

Click on the thumbnail images in the text below to bring up the full-sized graphic
 

June Precipitation and Temperatures, and Current Drought

June brought little relief for our drought-stricken region, with only northeastern Wyoming and portions of southeastern Colorado seeing above-average precipitation. Most of Utah, far western Colorado, and parts of southwestern Wyoming received virtually no precipitation. The HPRCC Water Year Precipitation map still shows only isolated areas with above-average precipitation since October 1.

June temperatures were warmer than average across the region, with most areas being 2-6°F above monthly average temperatures.

The latest US Drought Monitor, representing conditions as of July 2, shows an expansion of D3 (extreme) drought conditions since early June in the Four Corners region, extreme south-central Utah, and far northeastern Colorado. An area of abnormally dry (D0) conditions along Colorado's Front Range has deteriorated to D1 (moderate drought). The region on the whole is experiencing a similar proportion of severe (D2) or worse drought compared to early July 2012, though with a different spatial pattern than last year.

Current Streamflows

In the maps of current streamflows across the three states, there are many more gages in the below-normal categories than the above-normal categories. The runoff peak has passed at all gages, and western Colorado in particular has seen many gages drop categories in the last month. For example, the Colorado River near the CO-UT State Line dropped from the 15th percentile on June 7, to the 8th percentile (36% of median flow) on July 1.

The observed volumes this spring and early summer have been on track with the dry outlook of the official forecasts. With the low June precipitation, the observed unregulated inflows to Lake Powell are running below the "most probable" forecast of 3.0 MAF for the April–July period, and will likely end up closer to 2.7 MAF for the period, which would make it the 5th lowest spring runoff on record, just below 1981 but above 2012.

Reservoir Storage

The second year of below-average runoff has further depleted the region’s water storage. At the end of June, most reservoirs across the region had less storage than last year, and the vast majority were below the long-term average for the date. There was some recovery of reservoir storage in the Upper Colorado headwaters and the adjacent portion of the South Platte basin with near-average runoff there, but storage decreases were predominant in other basins, including the North Platte, Arkansas, Rio Grande, San Juan, Green, and the Wasatch Front basins. On June 30, Lake Powell held 11.76 MAF (48% full), down from 15.29 MAF (63% full) last year.

Seasonal Climate and Drought Forecasts

The latest monthly Climate Outlooks released on June 30 by NOAA CPC show a wet tilt for precipitation for July in far southern Utah and Colorado, reflecting the expectation for an active Southwest monsoon. The seasonal outlooks released June 20 show a tilt towards drier-than-average conditions for the July–September and August–October periods only for far northwestern Wyoming, and no tilt for the rest of the region. The CPC Climate Outlooks once again show enhanced odds for above-normal temperatures for the upcoming seasons, consistent with the long-term warming trend. The latest CPC Seasonal Drought Outlook released June 20 projects that drought conditions will persist for most of our region, but some improvement is expected in far southern Utah and extreme southwestern Colorado over the next three months, again reflecting the monsoon.

ENSO indicators continue to show ENSO-neutral conditions. Since last fall, ENSO conditions have not exerted much influence on the climate system, nor on the seasonal forecasts. The models in IRI's mid-June ENSO Prediction Plume again indicate a consensus towards ENSO-neutral conditions continuing through the fall, with the dynamical models tending towards the warm side of neutral, and the statistical models tending to stay on the cool side, with a few models calling for development of La Niña conditions by the end of summer.

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