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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.

Monday, April 18, 2022

SPC Apr 18, 2022 0730 UTC Day 3 Severe Thunderstorm Outlook

SPC 0730Z Day 3 Outlook Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0223 AM CDT Mon Apr 18 2022 Valid 201200Z - 211200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE WEDNESDAY AFTERNOON AND EVENING ACROSS PARTS OF SOUTHEASTERN KANSAS...SOUTHWESTERN MISSOURI...CENTRAL AND EASTERN OKLAHOMA....NORTH CENTRAL TEXAS...AS WELL AS PARTS OF WESTERN OREGON... ...SUMMARY... A couple of supercells are possible late Wednesday afternoon and evening, near or east of the Interstate 35 corridor between Kansas City and the Dallas-Fort Worth Metroplex. A few storms may also impact areas west of the Oregon Cascades, accompanied by at least some risk for severe weather. ...Synopsis... Models indicate little change to the general large-scale pattern impacting North America through this period, with short waves remaining progressive within the main belt of westerlies emanating from the mid-latitude Pacific. This includes one major, and still amplifying, large-scale trough across the eastern Pacific, which appears likely to begin advancing inland across the Pacific coast. Downstream, a significant lead short wave trough is forecast to migrate across and northeast of the Canadian Maritimes, accompanied by a relatively deep, occluded surface cyclone. In its wake, cold/dry surface ridging will maintain considerable influence across much of the Atlantic seaboard through the northeastern and central Gulf of Mexico. The most prominent trailing perturbation across interior North America is likely to dig within an increasing confluent regime east-southeast of the central Canadian/U.S. border vicinity toward the upper Great Lakes. Models indicate little further deepening of the primary associated surface cyclone, and it may tend to weaken while migrating from southern Saskatchewan into Ontario. A trailing cold front appears likely to advance southward through the Upper Midwest and northern Great Plains by late Wednesday night, preceded by a surge of cooler air east-southeast of the northern and central Great Plains into the lower Great Lakes, Ohio Valley, and Ozark Plateau. Modest pre-frontal low-level moistening may continue from near the Mexican Gulf coast northward through the southeastern Great Plains and middle Mississippi Valley, mostly beneath a plume of warm and capping elevated mixed-layer air emanating from the southern Rockies/Mexican Plateau vicinity. This warm mid-level air might become suppressed across parts of the central Great Plains, before returning northeastward again in the wake of the short wave trough passing to the north. ...I-35 corridor from Kansas City to Dallas-Fort Worth... In the wake of fairly widespread convection and embedded thunderstorms driven by elevated moisture return within a lower/mid tropospheric warm advection regime, models indicate that a narrow corridor of modest boundary-layer based instability may develop along the trailing cold front and dryline by late Wednesday afternoon. Mid/upper support for convective initiation remains unclear, and guidance generally suggests that renewed thunderstorm development might be widely scattered to isolated. However, although strong low-level wind fields may be in the process of shifting east of the region, the environment probably will be conducive to supercells in the presence of strong deep-layer shear, accompanied by at least the potential to produce large hail and locally strong wind gusts. The cold front/dryline intersection would seem one possible focus for convective initiation, but considerable spread exists within model output on where this will end up. And the influence of possible lingering outflow from the preceding elevated convection is an added uncertainty. Once these are cleared up, it possible severe thunderstorm probabilities could still be increased for this period. ...Pacific Northwest... Models suggest that the weakly unstable warm sector, of a broad and deep occluded surface cyclone centered over the northeastern Pacific, may spread inland to the west of the Oregon Cascades during the day Wednesday. It appears that this will coincide with mid-level cooling and lift within the exit region of 90+ kt 500 mb jet nosing onshore, and enlarging, clockwise curved low-level hodographs near a 40-50+ kt southerly 850 mb jet. And it might not be out of the question that the environment could become conducive to low-topped supercells with the potential to produce a tornado, locally strong wind gusts and/or small hail. ..Kerr.. 04/18/2022 Read more CHECK UPDATE ZOOM GRAPHIC