National Weather Service United States Department of Commerce

Widespread Precipitation and Snow Across the Pacific Northwest; Heavy Rain and Severe Thunderstorms Across the Central and Southern U.S.

Widespread precipitation is expected across the Northwest and northern Rockies through Monday, including heavy mountain snow for parts of the region. A powerful storm is expected to bring periods of heavy rain, gusty winds, and the potential for severe thunderstorms throughout the southern to central Plains between tonight and Monday. Read More >

Overview:

(Please note: Any official rainfall totals cited below are from either NWS cooperative observers or NeRAIN/CoCoRaHS observers)

Between the afternoon of Tuesday, Aug. 15th and the morning of Wednesday the 16th, roughly the northern half of the NWS Hastings coverage area saw its most widespread heavy rain event of the year-to-date. Most areas generally north of a line from Kearney-Hastings-York received AT LEAST 2-4", with localized pockets of 5-7+". South of this line, the majority of the remainder of the local area received only 1-2". Some of the overall-highest amounts targeted the following areas:1) Over much of Polk County (including 8.37" northeast of Osceola and 6.95" in town)...2) Much of Nance County...3) A corridor running from the north side of Hastings to around Aurora (including 6.70" five miles southeast of Phillips)...4) roughly the northwest half of Valley County (including 5.50" a few miles south of Burwell). At Osceola, the official NWS observer total of 6.95" set a new all-time 24-hour record for that station!

While some of this heavy rain was much-needed/appreciated, not surprisingly, at least minor flooding ensued across several counties, affecting not only numerous rural roads and agricultural areas, but also several creeks and rivers, including: 1) The Big Blue River, Clear Creek and Davis Creek in Polk County, the Lincoln Creek and Beaver Creek in Hamilton and York counties, and the West Fork Big Blue River mainly between northwestern Clay and southern Hamilton counties. Most of this flooding, especially outside of Polk County, was relatively minor and confined to "typical" flood-prone areas, but some of it persisted for at least 36-48 hours.

While heavy rain and flooding was the "big story" with this event, there were isolated instances of large hail/damaging winds as well. One of the areas hardest-hit by hail was in/near Fullerton, where stones up to baseball size fell. Wind-wise, estimated 70 MPH gusts were reported near Loup City on the afternoon of the 15th, while much later that night the Phillipsburg KS airport measured 67 MPH. 

Turning to the meteorological background behind this heavy rain/isolated severe weather event, the primary factors (above all else) were: 1)  the presence of a very humid/most airmass characterized by surface dewpoints in the upper 60s-low 70s...2) a generally west-oriented surface front stretched near the Interstate 80 corridor...3) A nocturnal low level jet stream featuring moisture-laden southerly winds of at least 35-40 MPH feeding storms as they continuously redeveloped along/north of the surface front. 
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Please note: Information in this story is considered preliminary and subject to change until publication in NOAA Storm Data. Click here to search official reports in the NCEI Storm Events Database (new storm reports do not appear here for at least 2-3 months from when they occur) 


NWS Hastings radar loop from 3:45 p.m. on Aug 15th -9 a.m. CDT on Aug 16th. The NWS Hastings coverage area is outlined in orange and interstates are in red.
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