USA: Three outbreaks in one: Active day of severe weather in the Great Plains | WeatherWatch.co.nz

USA: Three outbreaks in one: Active day of severe weather in the Great Plains


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Several rounds of severe thunderstorms will rumble across Tornado Alley from Tuesday afternoon to early Wednesday morning. The NOAA/NWS Storm Prediction Center tagged a belt from Iowa to Texas with an enhanced risk of severe weather in its Tuesday outlook, surrounded by a larger slight-risk area. A small part of western Oklahoma and the eastern TX panhandle was upgraded to a moderate risk in SPC’s 11:30am update CDT.

The entire gamut of severe weather could materialize on Tuesday, including one or more strong tornadoes, giant hail, wind gusts topping 120 kmh, and extremely heavy rain. However, these threats will not be distributed evenly across the SPC risk areas.

U.S. convective outlook issued by NOAA/SPC at 1630Z 5/16/2017
Figure 1. WU depiction of severe weather risk guidance for Tuesday, May 16, 2017 issued by the NOAA/NWS Storm Prediction Center at 11:30 am CDT.

Conditions appear more volatile for Tuesday than they were on Monday, which itself produced more than 140 preliminary reports of severe wind and hail, mainly over the central High Plains and Upper Midwest. A swath of deeper low-level moisture pushed north through Texas overnight and was proceeding toward the Central Plains on Tuesday. Later on Tuesday, a very potent slug of upper-level energy and cold air aloft (a short wave) will rotate around a large upper-level trough over the western U.S. The juxtaposition of the short wave and warm, moist surface air will produce a broad band of very unstable air.

As well described by SPC forecasters Roger Edwards and Greg Dial, Tuesday’s outbreak of severe weather should arrive in three distinct phases...

View the rest of this story here (via Wunderground)

- Photo: This supercell thunderstorm produced hail up to baseball size near the town of Stinnett as it moved through the Texas Panhandle north of Amarillo on Monday night, May 15, 2017. Image credit: © Matt Crowther, Wunderground.