March 17, 2005
NOAA News

Spring 2005 Temperature Outlook

Today, NOAA unveiled the 2005 U.S. Spring Outlook for April through June. Of significance, one of the wettest winters on record has resulted in major reductions in the area and severity of drought in the Southwest and the Colorado River Basin—the first time this has occurred in five years. (Click for larger view of NOAA spring 2005 temperature outlook.

"The same winter climate patterns that brought record rainfall and deadly mudslides to California have lessened drought conditions that have plagued portions of the Southwest since 1999," said retired Navy Vice Adm. Conrad C. Lautenbacher, Ph.D., undersecretary of commerce for oceans and atmosphere and NOAA administrator. "However, one season of improvement does not bring complete drought relief."


Spring 2005 Precipitation Outlook

Short-term drought concerns have been alleviated in many areas of the Southwest especially southern California, Nevada, Utah, Arizona, New Mexico and Colorado. Preliminary data show the Southwest had its wettest September-February in 110 years of record keeping. Abundant snowpack in the upper Colorado River Basin is resulting in above-normal inflow to the region's reservoirs. However, with reservoir storages at 17 percent capacity in Nevada and 29 percent capacity in New Mexico, local water supply problems are still possible. (Click for larger view of NOAA spring 2005 precipitation outlook.

The unusual southward shift in the winter storm track that helped the Southwest has resulted in deficient rain and snow to the north. Moderate to severe drought developed over the winter in portions of the Pacific Northwest. Some mountain observation sites in Idaho, Montana and Washington were snowless in early March for the first time in more than 30 years. Long-term drought has continued in the northern Rockies and the upper Missouri River Basin.


El Niño/La Niña Conditions

NOAA's El Niño experts expect the currently weak El Niño conditions to continue to fade with a return to neutral conditions (neither El Niño nor La Niña) during the spring. Neither El Niño nor La Niña will be an influencing factor in weather and climate patterns across the U.S. this season. (Click for larger view of NOAA drought outlook through June 2005.


Spring Drought Outlook

Spring Precipitation/Temperature Outlook

NOAA's seasonal outlook calls for warmer-than-normal temperatures in parts of the West, Southwest, the mid-Atlantic, Southeast, Alaska and Hawaii. Parts of the western Great Lakes and the southern Plains are expected to be cooler-than-normal. Above-normal precipitation is expected in parts of the western Great Lakes, southern Plains and most of Alaska, with drier-than-normal conditions expected in Hawaii and parts of Florida and California.

The latest Seasonal Drought Outlook indicates drought is likely to continue across the Northwest and northern Rockies into June, with only some temporary improvement for parts of the region. (Click for larger view of drought monitor as of March 15, 2005.)

A shift in the weather pattern during the last half of March will bring a more favorable storm track toward the region, suggesting that limited improvement is on tap, especially from the Cascades to the coast. However, it is unlikely that significant drought improvement can develop for most of the region this late in the wet season, given the near-record low mountain snowpacks.

Across the northern High Plains, some drought improvement is anticipated by late spring, although low winter snowpack ensures that the reservoir levels in the Missouri Basin will remain a concern.


Spring Flood Outlook

There is an elevated risk for flooding in parts of the Southwest. As a result of a very wet winter, plentiful snowpack combined with wet soils and high stream flows leave this area susceptible to flooding if there is future heavy rain and/or rapid snow melt. Low reservoir levels will allow water managers more options to mitigate possible flooding. Burn areas remain susceptible to flash flooding and debris flows. (Click for larger view of NOAA spring 2005 flood risk.)

Some degree of flooding in the Red River basin (North Dakota-Minnesota) is expected but at levels unlikely to approach those of the catastrophic flooding in 1997.

In northern New England, an unusually heavy snow pack combined with thick river ice raises concern for possible flooding this spring.

NOAA cautions that spring weather can change abruptly. "Even during droughts, spring rains can still lead to flooding, particularly flash and small stream flooding that can inundate roadways," said Lautenbacher. "On average, floods kill more than 100 people and more than half of these deaths occur when vehicles are swept away by rushing floodwaters. Remember, when approaching a flooded roadway Turn Around, Don't Drown."

http://www.noaanews.noaa.gov/stories2005/s2406.htm