From the frigid cold and heaps of snow in the Midwest and Northeast to the unyielding drought in California, winter proved ruthless in many parts of the U.S. The spring season will pose challenges of its own, NOAA cautioned today, in releasing its spring outlook.
Drought in California is predicted to persist or intensify and up to half of the rivers in the U.S. are prone to minor to moderate flooding as snow melts and spring rains arrive. Little relief is likely for some of the areas hardest hit by cold.
California drought to persist or intensify
The latest U.S. National Drought Monitor declares nearly 100 percent of California (99.8 percent) under at least moderate drought, a four percent increase since last week. The state just experienced its warmest and third driest winter on record. Snowpack in many areas is less than 50 percent of normal.
Now comes the dry season when rain- and snow-producing weather systems become increasingly rare, especially in southern California.
” If the drought persists as predicted in the West and Southwest, it will likely result in an active wildfire season, continued stress on crops and livestock due to low water levels, and an expansion of water conservation measures,” NOAA warns.
While drought is predicted to persist or worsen in large areas of the western U.S., some improvement is expected in the Midwest and Southern Plains from spring precipitation and snowmelt.
Widespread river flooding risk
Spring rains and melting snow and ice, while moistening soils, will cause many rivers to swell.
“This year’s spring flood potential is widespread and includes rivers in highly populated areas putting millions of Americans at risk,” said Louis Uccellini, director of the National Weather Service. “Although widespread major river flooding is not expected, an abrupt warming or heavy rainfall event could lead to isolated major flooding.”
NOAA highlights the southern Great Lakes region as having the highest flood risk due to above normal snow cover, as well as frozen ground (which will enhance run-off), but there are also pockets of moderate flood risk in the Northern Plains.
Rivers at risk of flooding include the Mississippi and Illinois rivers near the Great Lakes and Souris and Red rivers in the northern Plains.
Ice jams are another concern in rivers across the northern U.S. from Montana through the Great Lakes and into the Northeast.
“The ice jam risk from river and streams draining into Lake Erie is high,” warned NOAA hydrologist Robert Hartman.
Staying cold up North
Spring-like weather is likely to be delayed for cold weather-weary residents of Northern Plains and Great Lakes. NOAA’s 90-day outlook calls for colder than the normal conditions from northern Montana to northern Michigan.
Largely to blame? The unusual amount of remaining snow and ice cover in that region, acting like a refrigerator. Ice cover on the Great Lakes in early March reached near-record levels.
“The [Great Lakes] ice and snow contributed equally to the temperature outlook [in that region],” said Jon Gottschalk , a forecaster at NOAA’s Climate Prediction Center.
Spring precipitation and severe weather are wild cards
The amount of rain which falls in vulnerable flood regions will play a deciding role in whether impacts are minor or major. But aside from the dry weather expected in California and parts of the West, NOAA forecasters stopped short of leaning one way or another on precipitation amounts. Much of the country has equal chances of normal, above normal, or below normal precipitation through June, they concluded.
“Climate signals are very weak,” said NOAA’s Gottschalk, noting the amount of the country covered by “equal chances” of having above, below, or near normal precipitation was “near a record.”
Gottschalk said if there was a strong El Nino or La Nina, it would make the spring precipitation outlook more straight forward.
“We”re in transition from neutral [neither an El Nino or a La Nina] to a possible developing El Nino,” Gottschalk noted. “That further adds to the complication.”
The “possible” El Nino is not expected to have major impacts in the U.S. this spring, Gottschalk said.
When queried about anticipated tornado activity, Gottschalk said seasonal severe weather prediction is an active research area, but not ready for prime time.
“Officially NOAA does not make severe weather outlooks,” Gottschalk said. “The impact [of this spring's weather patterns] on the tornado season is unknown.”