MARCH 19, 2015
U.S. Spring Flood Risk Map for 2015. (Credit: NOAA)
According to NOAA’s Spring Outlook released today, rivers in
western New York and eastern New England have the greatest risk of spring
flooding in part because of heavy snowpack coupled with possible spring rain.
Meanwhile, widespread drought conditions are expected to persist in California,
Nevada, and Oregon this spring as the dry season begins.
“Periods of record warmth in the West and not enough
precipitation during the rainy season cut short drought-relief in California
this winter and prospects for above average temperatures this spring may make
the situation worse,” said Jon Gottschalck, chief, Operational Prediction
Branch, NOAA’s Climate Prediction Center.
NOAA’s Spring Outlook identifies areas at risk of spring
flooding and expectations for temperature, precipitation and drought from April
through June. The Spring Outlook provides emergency managers, water managers,
state and local officials, and the public with valuable information so they
will be prepared to take action to protect life and property.
Spring Flood Risk
Record snowfall and unusually cold temperatures in February
through early March retained a significant snowpack across eastern New England
and western New York raising flood concerns. Significant river ice across
northern New York and northern New England increase the risk of flooding
related to ice jams and ice jam breakups. Rivers in these areas are expected to
exceed moderate flood levels this spring if there is quick warm up with heavy
rainfall.
There is a 50 percent chance of exceeding moderate flood
levels in small streams and rivers in the lower Missouri River basin in
Missouri and eastern Kansas which typically experience minor to moderate
flooding during the spring. This flood potential will be driven by rain and
thunderstorms.
Moderate flooding has occurred in portions of the Ohio River
basin, including the Tennessee and Cumberland rivers from melting snow and
recent heavy rains. This has primed soils and streams for flooding to persist
in Kentucky, southern Illinois, and southwest Indiana with the typical heavy
spring rains seen in this area.
Minor river flooding is possible from the Gulf Coast through
the Ohio River Valley and into the Southeast from Texas eastward and up the
coast to Virginia. The upper Midwest eastward to Michigan has a low risk of
flooding thanks to below normal snowfall this winter. Though, heavy rainfall at
any time can lead to flooding, even in areas where overall risk is considered low.
Drought Outlook
El Niño finally arrived in February, but forecasters say
it’s too weak and too late in the rainy season to provide much relief for
California which will soon reach its fourth year in drought.
Drought is expected to persist in California, Nevada, and
Oregon through June with the onset of the dry season in April. Drought is also
forecast to develop in remaining areas of Oregon and western Washington.
Drought is also likely to continue in parts of the southern Plains.
Forecasters say drought improvement or removal is favored
for some areas in the Southwest, southern Rockies, southern Plains, and Gulf
Coast while drought development is more likely in parts of the northern Plains,
upper Mississippi Valley and western Great Lakes where recent dryness and an
outlook of favored below average precipitation exist.
Current water supply forecasts and outlooks in the western
U.S. range from near normal in the Pacific Northwest, northern Rockies, and
Upper Colorado, to, much below normal in California, the southern Rockies, and
portions of the Great Basin.
If the drought persists as predicted in the Far West, it
will likely result in an active wildfire season, continued stress on crops due
to low reservoir levels, and an expansion of water conservation measures. More
information about drought can be found at www.drought.gov.
Temperature and Precipitation Outlook
Above-average temperatures are favored this spring across
the Far West, northern Rockies, and northern Plains eastward to include parts
of the western Great Lakes, and for all of Alaska. Below normal temperatures
are most likely this spring for Texas and nearby areas of New Mexico, Colorado,
Kansas, and Oklahoma.
For precipitation, odds favor drier than average conditions
for parts of the northern Plains, upper Mississippi Valley, western Great
Lakes, and Pacific Northwest. Above average precipitation is most likely for
parts of the Southwest, southern and central Rockies, Texas, Southeast, and
east central Alaska. Hawaii is favored to be warmer than average with eastern
areas most likely wetter than average this spring.
Now is the time to become weather-ready during NOAA’s Spring
Weather Safety Campaign which runs from March to June and offers information on
hazardous spring weather -- tornadoes, floods, thunderstorm winds, hail,
lightning, heat, wildfires, and rip currents -- and tips on how to stay safe.
NOAA’s mission is to understand and predict changes in the
Earth's environment, from the depths of the ocean to the surface of the sun,
and to conserve and manage our coastal and marine resources. Join us on Facebook, Twitter,
Instagram and our other social media channels.