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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.

Friday, April 22, 2022

SPC Apr 22, 2022 2000 UTC Day 1 Convective Outlook

SPC 2000Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0253 PM CDT Fri Apr 22 2022 Valid 222000Z - 231200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL AND SOUTHERN HIGH PLAINS... ...SUMMARY... At least isolated significant severe weather is possible across portions of the High Plains late this afternoon and tonight. Very large hail, damaging straight-line winds, and a few tornadoes are anticipated. ...20Z Update... Recent surface analysis depicts a deepening low over the central High Plains, with surface pressure falls around 3-4 mb over the last 2 hours. A dryline currently extends from western NE southward through western KS into far eastern NM. Some cumulus is beginning to form in the vicinity of this boundary, although the character of this cumulus suggests convective initiation is likely still an hour or two away. This matches recent runs of the WoFS, which depicts development around 21-22Z. Overall forecast outlined in the previous outlook (discussed below) remains unchanged, with no changes needed. Recent 19Z AMA and DDC soundings shows very steep lapse rates in place, supporting strong buoyancy. Kinematics will continue to improve as the upper trough continues to approach from the west. As noted in the previous discussion, all severe hazards are still expected, including very large hail, strong wind gusts over 74 mph, and tornadoes. ..Mosier.. 04/22/2022 .PREV DISCUSSION... /ISSUED 1129 AM CDT Fri Apr 22 2022/ ...Southern/central High Plains... Early morning /12z/ upper-air analysis features relatively rich mid/late-April moisture across the region, with 12+ C 850mb dewpoints across western Kansas and all of west Texas (DDC-AMA-MAF-DRT) with the moist axis roughly centered along 101W longitude. Early/mid-morning visible satellite trends already depict a relatively quick erosion of the southern High Plains stratus field, particularly on its western edge near the New Mexico/Texas border vicinity. This moisture is beneath a stout elevated mixed layer and generally coincides with the early day mid-level warm axis with 700mb temps 10-12C. Ahead of the upper trough/polar jet spreading from the Southwest Deserts toward the Four Corners area, robust surface cyclogenesis will occur today across northeast Colorado toward western Nebraska by evening. As mid-level height falls occur and mixing and confluence/convergence increases near the dryline, current thinking is that at least widely scattered storms will begin to develop by around mid-afternoon within a north-south corridor spanning areas from far west Texas to near/just west of the New Mexico/Texas into southeast/east-central Colorado. Although some warm-sector mixing/lowering of dewpoints can be expected, mid 50s to low 60s F surface dewpoints are expected to generally persist the east of the dryline, supporting a likely intensification as storms progress eastward. 35-40 kt of effective shear will support initial high-based supercells capable of very large hail. Deep-layer/low-level shear will tend to increase through early/mid-evening, while storms will also encounter increased moisture content and less mixing. This should result in an increased potential for tornadoes by early evening, while strong convective wind gusts are also plausible. A later round of separate convective development is likely by late evening as the Pacific cold front moves eastward and impinges on the western extent of the buoyancy plume near the Nebraska/Colorado/Kansas border area. This should result in a north/south-oriented convective line quickly spreading into western portions of Nebraska/Kansas, while also expanding southward regionally overnight. Very strong wind profiles should promote a threat for severe wind and some hail, although duration and spatial extent overnight will probably be limited by the pervasive cold low-level theta-e advection in the warm sector, which will reduce available CAPE with time. ...Far eastern Wyoming/western South Dakota/northwest Nebraska... A tight baroclinic zone will lie to the north of the slow-moving warm front/quasi-stationary frontal zone extending from the deepening central High Plains cyclone. A narrow bent-back plume of 50s F surface dew points should be maintained beneath an initially stout elevated mixed layer. It seems likely that a few surface-based storms may ride along the boundary within an SRH-enriched environment near the SD/NE border area, while additional storms are possible farther west-northwest. Hodographs will be highly elongated, yielding the potential for a longer-lived supercell or two, with the main threat being significant large hail, although a couple of tornadoes could also occur. ...Upper Midwest... Pending some additional destabilization near a warm front, isolated strong to severe storms could occur today near/east of an MCV currently across eastern Iowa. Otherwise, additional potentially severe development (mostly hail) is possible later tonight across a broader part of the Upper Midwest in association with a low-level warm theta-e advection regime. This potential will be supported by steepening mid-level lapse rates attendant to an expanding Great Plains elevated mixed-layer and adequate shear within the cloud-bearing layer. Read more CHECK UPDATE ZOOM GRAPHIC