Atmospheric River to Impact the Northwest; Windy Conditions in the Northeast

A strong atmospheric river moving into northern California later today will bring a threat for moderate to heavy rainfall and flooding, gusty to high winds, and mountain snows for parts of the Northwest U.S. through Wednesday. Gusty winds and isolated showers are expected today in the Northeast U.S. behind a cold front. Wind Advisories have been issued. Read More >

Overview

A powerful supercell storm produced wind gusts estimated around 80 mph and small tornado in eastern Kiowa County. In addition, hail up to the size of tennis balls occurred causing damage to vehicles and structures. Kiowa County law enforcement have been checking with local residents and assessing damage in eastern Kiowa County.

A trained weather spotter reported a small tornado just east of Sheridan Lake, which pushed his vehicle off the road and caused minor damage to a house just south of the road. The description was consistent with EF0 damage, with updates to follow.

The Plainview School, 4 miles east of Sheridan Lake, sustained broken windows, snapped trees, and downed power lines.

There was a report of some damage to a house in far northeast Prowers County by the emergency manager, with more details to follow. Many storm chasers witnessed the storm across eastern Colorado, and as of 715 p.m MDT, no photos or videos of tornados have been submitted to NWS Pueblo.

Base Reflectivity an Base Velocity Radar Volume Scans

Differential Reflectivity and Correlation Radar Volume Scans

Photos & Video
Environment

Photos & Video:

Header

Tennis Ball Sized Hail from the Storm; Photo Taken by Sheila Mayhan Allen

Environment

The Storm Prediction Center in Norman, Oklahoma issued a slight risk for severe weather over where the tornadic/hail event took place. In there discussion, they covered that an mesoscale convective system (MCS) that formed in Kansas would output a westerly propagating outflow boundary, and that outflow boundary would interact with a lee trough over eastern Colorado. The outflow boundary did, indeed, interact with a lee trough, enhancing the low-level wind shear in Kiowa County, which ultimately initiated tornadogenesis and helped create the very large hail. The lee trough is seen on the 6:00 AM and 6:00 PM MDT 700-hPa SPC Upper-Air map provided below. Other lifting mechanisms that can be observed is an area of upper-level divergence, caused by an upper-level diffluent zone stationed over eastern Colorado. Now focusing on the upper-air soundings, the 6:00 AM MDT KDNR sounding illustrates a a sheared environment, with a helicity magnitude of 143 m^2/s^2. The KDDC 6:00 AM MDT sounding doesn't show favorable shear, but does have 537 J/kg of CAPE, only to be enhanced by daytime heating. The 6:00 PM MDT KAMA sounding (which was after the storm) illustrates that the CAPE, southeast of the storm, had magnitudes of 1026 J/kg, which is favorable for supercells. Thermodynamically, July 15, 2016 had the ingredients for supercell storms, but the outflow boundary from the MCS in Kansas the previous day enhanced the low-level shear to spawn a tornado.

SPC 6:00 AM MDT Convective Outlook

SPC Upper-Air Map on July 15th, 2016 at 6:00 AM MDT


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SPC Upper-Air Map on July 15th, 2016 at 6:00 PM MDT


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Sounding on July 15th, 2016 at 6:00 AM MDT (From Plymouth State University)


KDDC Sounding	KDNR Sounding

Sounding on July 15th, 2016 at 6:00 PM MDT (From Plymouth State University)


KAMA Sounding (KDDC Was Unavailable)	KNDR Sounding

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Atmospheric River to Impact the Northwest; Windy Conditions in the Northeast

Powerful supercell hit far eastern Colorado