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Archives for the SPC Convective Outlook are updated daily (approximately) with a live map at the beginning of each article. Follow the link at the end of the article to check for current updates on the NOAA/NWS Storm Prediction Center website. Also, see Archives for Chicago's hourly weather data on CARDINAL NEWS Magazine.


Wednesday, November 10, 2021

SPC Nov 10, 2021 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0159 PM CST Wed Nov 10 2021 Valid 102000Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF OK/NORTH TX AS WELL AS NORTHEAST KS/SOUTHEAST NE/SOUTHWEST IA/NORTHWEST MO... ...SUMMARY... Scattered severe thunderstorms are possible across eastern Kansas, southeast Nebraska, northwest Missouri, and southwest Iowa, as well as central/eastern Oklahoma into north Texas, mainly during the late afternoon and evening. Large hail, damaging winds, and a couple of tornadoes are possible. ...20Z Update... ...Central/Eastern OK...North-Central/Northeast TX...Western AR/Arklatex... Recent surface analysis places a low over southeast NE. A cold front extends southwestward from this low through central KS and western OK to another low in the southeast TX Panhandle. Temperatures ahead of the front range from the low 60s in southeast NE to the low/mid 70s across north TX and dewpoints range from the upper 50s to low 60s over the same area. Mesoanalysis estimates an area of 8.5+ deg C per km max lapse rates between 2 and 6 km covers much of southern KS, OK, and north TX. These steep mid-level lapse rates are will support moderate buoyancy across OK and north TX, despite cool temperatures and relatively modest low-level moisture. In addition to this buoyancy, the current flow field across this region is sufficient for updraft organization/rotation, with low-level southerly flow veering/increasing to southwesterly at 50 kt at mid levels, per the latest KTLX WSR-88D VWP. Overall forecast reasoning remains unchanged across this region, with the previously described conditions supporting an initially supercellular storm mode capable of all severe hazards, including very large hail and a tornado or two. Greatest tornado threat is over south-central OK and north-central TX. A more linear storm mode is expected along and ahead of the front as it moves eastward into more of eastern OK, northeast TX, western AR, and the Arklatex. ...Eastern KS/Southeast NE/Northwest MO/Southwest IA... The threat for a few severe thunderstorms capable of damaging wind gusts and hail continues across the region for the next several hours. Severe Thunderstorm Watch 546 was just issued to address this severe potential. ..Mosier.. 11/10/2021 .PREV DISCUSSION... /ISSUED 1032 AM CST Wed Nov 10 2021/ ...OK/TX/AR/LA... Wind profiles and the orientation of the front appear favorable for supercell development this evening, especially across parts of Oklahoma and possibly nearby North Texas. Strong boundary-layer heating will occur across western North Texas where surface temperatures should warm into the low 80s F. Downstream of this low-level warm nose, the greatest buoyancy is expected to be centered on south-central Oklahoma where MLCAPE should approach 1500 J/kg by early evening. Increasing convergence along the sharpening front should yield late afternoon thunderstorm development in northern Oklahoma, spreading south through the evening along the I-35 corridor into north Texas. Very steep (8-9 C/km) mid-level lapse rates owing to a combination of an elevated mixed-layer and cool mid-level temperatures within the trough will support a risk for significant severe hail with initial discrete supercells. Sufficient hodograph curvature should also exist for a tornado threat as well, particularly in the 00-03Z time frame. An increasingly linear convective mode is likely to evolve across eastern Oklahoma into northeast Texas tonight. This linear MCS will likely spread southeastward into parts of western Arkansas/northwest Louisiana, but weaker surface-based instability coupled with stronger forcing for ascent shifting away from the region suggests the wind/tornado threat should gradually diminish overnight. ...Eastern KS/southeast NE/northwest MO/southwest IA... Have introduced a categorical Slight Risk for the region, with at least isolated severe thunderstorms expected by early/mid-afternoon, initially across eastern Kansas and far southeast Nebraska. Large-scale ascent tied to the more northern of the shortwave impulses will support such an increase in thunderstorms near the cold front/surface low. Although cloud cover may tend to linger, upwards of 1000 J/kg MLCAPE is plausible within the warm sector. A few semi-discrete supercells may initially occur, but a relatively quick upscale quasi-linear growth is otherwise anticipated as storms quickly spread toward northwest Missouri/southwest Iowa. Read more LIVE:
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