WASHINGTON, D.C. -- Forecasters at the National Weather Service (NWS) are projecting more heavy rain and severe weather for much of the central U.S. between May 14 and May 21. From May 14 through May 16, another series of complex storms will come out of the Rockies and bring the threat of thunderstorms with locally heavy rain and possible severe weather to much of the Great Plains and upper Mississippi Valley.
Eastern North Dakota and northeastern South Dakota, which have already seen some flooding, could see significant total rainfall amounts of up to two inches that could worsen the situation over the forecast period. Some areas in the Missouri and Mississippi River valleys could see the threat of flash flooding during locally heavy rain.
The threat of thunderstorms and severe weather during the forecast period could mean the return of tornadoes and high winds to the central and southern Plains states. Conditions favorable to the development of tornadoes will be present as the low-pressure system makes its way across the county next week.
In other areas of the country, dry weather will dominate the conditions over the forecast period. The New England states will see continuing dryness that is increasing the wildfire danger. A NWS forecaster noted that New England has had a precipitation deficit over the winter and spring. The forecast models are not calling for any significant widespread rain in that area during the next week.
Dry conditions will be present from the Middle Atlantic States southward through the Southeastern U.S. and along the immediate Gulf Coast. Drought conditions continue across much of the Southwestern U.S. where with high winds will create an increase in the wildfire danger over the next week. California and Nevada will see high winds.
The snow pack in the mountains of the Pacific Northwest continues to be a concern as cool temperatures over the area are retarding the spring snowmelt. Some areas in the Columbia/Snake River drainage have snow pack levels up to 165 percent of normal with a high water content. NWS Hydrology officials are concerned that a rapid warm-up could bring severe flooding conditions over a wide area of the Northwest. Fortunately, the projected temperatures over the short term will remain cool. However, a slow warm up is needed to drain off this massive snow pack.
The overall weather conditions across the U.S. continue to be driven by a strong La Nina pattern in the central Pacific Ocean. The low sea-surface temperatures are expected to continue into the winter and possibly longer, NWS forecasters said. This means that the present weather patterns could be a fixture over the next six to nine months.