Jason's Texas Weather and Adventure Blog

May 6, 2019: Severe Weather Threat in the Great Plains

The Storm Prediction Center has drawn a Slight Risk for severe weather which includes large portions of the Great Plains today. This outlook area includes the Texas Panhandle, though I think the greater threat for large hail (which is the main threat) will be to the north in southwestern Kansas. I wrote the following discussion below for a severe weather forecast challenge I am doing at my job this spring. To make a long story short, I expect thunderstorms to begin developing near and ahead of a dryline around 4 PM this afternoon, with these thunderstorms likely to become supercells. The main threat will be large hail and damaging winds, but a tornado isn’t totally out of the question.

An upper-level pattern characterized by deep troughing over the western CONUS continues today. Water vapor channel from GOES-16 shows the main vorticity maximum over Southern California…with a lead shortwave trough over the Sangre de Cristo range. [9 AM CDT] manual surface analysis reveals a 1008 mb surface low near [Lamar, CO]. A warm front extends northeast from this surface low towards [Hays, KS] and eventually [Falls City, NE]. A dryline extends south of the surface low…roughly along the New Mexico/Texas border. The warm sector is characterized by surface dewpoints in the mid 50s to near 60. Observed soundings within the warm sector reveal very steep mid-level lapse rates…in some cases larger than 8 C/km. High-resolution model guidance is in good agreement that deep convection should erupt in the vicinity of the triple point near the border of Colorado and Kansas around [4 PM CDT] this afternoon. Large hodographs on forecast soundings in close proximity to the convection suggest that supercells will be likely. Despite the large hodographs…LCLs will be somewhat high (around 1500-2000 m) which could limit the tornado risk to a degree. Even for the Central High Plains…these LCL values are fairly high compared to historic tornado climatology (according to the SPC Tornado Environment Browser…the median tornado event in this region occurs with an LCL of around 1200 m, with the interquartile range being 850-1500 m). Given the very steep mid-level lapse rates and large MUCAPE values in excess of 2100 J/kg…hail will be the primary risk factor (with significant hail very possible). Inverted-v profiles below the LCL and steep low-level lapse rates may also result in some damaging outflow winds…especially as thunderstorms grow upscale after [10 PM CDT] as suggested by most high-res guidance.

Jason Godwin’s discussion for the Warning Decision Training Division’s (WDTD) Severe Weather Forecast Challenge for May 6, 2019.
Day One Convective Outlook from the Storm Prediction Center, issued at 11:30 AM CDT
Dodge City, KS Radar Loop

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