{"id":51052,"date":"2023-03-11T23:59:00","date_gmt":"2023-03-11T23:59:00","guid":{"rendered":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/?p=51052"},"modified":"2023-03-14T01:35:49","modified_gmt":"2023-03-14T01:35:49","slug":"severe-thunderstorms-in-the-central-valley-of-california","status":"publish","type":"post","link":"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/archives\/51052","title":{"rendered":"Severe thunderstorms in the Central Valley of California"},"content":{"rendered":"
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GOES-18 \u201cRed\u201d Visible (0.64 \u00b5m, top) and \u201cClean\u201d Infrared Window (10.3 \u00b5m, bottom) images, with and without an overlay of GOES-18 GLM Flash Extent Density [click to play animated GIF | MP4<\/strong><\/a>]<\/p><\/div>\n

1-minute Mesoscale Domain Sector GOES-18 (GOES-West)<\/em>\u00a0\u201cRed\u201d Visible (0.64 \u00b5m<\/strong><\/a>) and \u201cClean\u201d Infrared Window (10.3 \u00b5m<\/strong><\/a>) images\u00a0(above)<\/em><\/strong> included an overlay of GLM<\/strong><\/a> Flash Extent Density — which showed thunderstorms that produced flash flooding, hail and an EF-1 tornado (SPC Storm Reports<\/strong><\/a>) in the Central Valley of California on 11 March 2023<\/strong><\/a>. At 2236 UTC<\/strong><\/a> (1 minute prior to the Tornado Warning being issued), an overshooting top along the Calaveras\/Tuolumne County line exhibited an infrared brightness temperature of -53.3\u00baC — which roughly corresponded to the altitude of a Most Unstable Maximum Parcel Level (MU MPL) as analyzed from the 0000 UTC Oakland rawinsonde<\/strong><\/a> (source<\/strong><\/a>).\u00a0 Note that for the relatively low-topped convection over California on this day, the coldest value of the default infrared enhancement was modified to -70\u00baC, to aid in the identification of colder overshooting tops (shades of white embedded within dark black regions). <\/p>\n

The corresponding GOES-18 Cloud Top Height<\/strong><\/a> derived product at 2236 UTC — just before the issuance of the Tornado Warning — was around 32,482 feet (below)<\/strong><\/em>. For this storm, the maximum value of the default Cloud Top Height enhancement was set to 35,000 feet.<\/p>\n

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GOES-18 \u201cRed\u201d Visible image (0.64 \u00b5m, top) and Cloud Top Height derived product (bottom), with cursor sampling of the coldest 10.3 \u00b5m pixel along the Calaveras\/Tuolumne County line at 2336 UTC [click to enlarge]<\/p><\/div>\n

During the period leading up to convective initiation of the hail\/tornado-producing thunderstorm, 1-minute GOES-18 Visible and Infrared images (below)<\/strong><\/em>\u00a0include contours of\u00a0LightningCast<\/strong><\/a> Probability — a >50% LightningCast Probability (green contour) over western San Joaquin County at 2009 UTC<\/strong><\/a> provided a 17-minute lead time to the start of a prolonged period of GLM-indicated lightning activity for that storm, which commenced at 2026 UTC<\/strong><\/a> (2000 – 0100 UTC animation<\/strong><\/a>).<\/p>\n

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GOES-18 \u201cRed\u201d Visible (0.64 \u00b5m, top) and \u201cClean\u201d Infrared Window (10.3 \u00b5m, bottom) images, with an overlay of GLM Flash Extent Density and contours of LightningCast Probability [click to play animated GIF | MP4<\/strong><\/a>]<\/p><\/div>\n

These thunderstorms developed in an environment of modest moisture and instability, as shown by 1-minute GOES-18 Visible and Infrared images combined with Total Preciptitable Water (TPW) and Convective Available Potential Energy (CAPE) derived products in cloud-free areas (below)<\/strong><\/em>. Satellite-derived TPW values up to 0.90 inch and CAPE values as high as 400 J\/kg were observed in the general vicinity of the strongest convection. Note that the default enhancements for TPW and CAPE were also modified for use with these particular storms — the maximum TPW value was set at 1.1 inches, while the maximum CAPE value was set at 500 J\/kg. <\/p>\n

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GOES-18 \u201cRed\u201d Visible (0.64 \u00b5m, top) and \u201cClean\u201d Infrared Window (10.3 \u00b5m, bottom) images, combined with Total Preciptitable Water and Convective Available Potential Energy (CAPE) derived products in cloud-free areas [click to play animated GIF | MP4<\/strong><\/a>]<\/p><\/div>\n\n\n

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We have determined a brief EF-1 tornado touched down 6SW of Tuttletown in Tuolumne County during yesterday's severe thunderstorms that also produced 1" hail and significant flash flooding. See map and press release for more info. #CAwx<\/a> pic.twitter.com\/bEHYHzolI4<\/a><\/p>— NWS Sacramento (@NWSSacramento) March 12, 2023<\/a><\/blockquote>