SPC Jun 24, 2022 0600 UTC Day 1 Convective Outlook

 SPC AC 240600 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Fri Jun 24 2022 Valid 241200Z - 251200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN NORTH DAKOTA...NORTHEASTERN SOUTH DAKOTA...AND NORTHWESTERN MINNESOTA... ...SUMMARY... Severe thunderstorms capable of severe wind gusts, very large hail, and a couple of tornadoes are possible across the northern Plains/upper Midwest region this afternoon and evening. ...Synopsis... Complex upper troughing -- comprised of several smaller-scale disturbances -- is forecast to move eastward across the Intermountain West during the day, and then into/across the northern and central Plains. With expansive upper ridging across roughly the southern half of the country, a belt of enhanced mid-level southwesterlies will reside over the north-central states. At the surface, progression of the upper trough will support eastward advance of a lee trough into the central Plains, while a cold front crosses the northern Rockies and shifts into the northern Plains. As these boundaries encounter the moist/strongly unstable afternoon boundary layer over the Plains, widespread thunderstorms and associated severe risk is expected. ...Northern and central Plains/Upper Midwest... As southerly low-level flow continues to advect rich low-level moisture northward, diurnal heating will result in a strongly unstable environment across the Dakotas and Nebraska, and into Minnesota, during the afternoon. As a cold front moves across Montana into western North Dakota/northwestern South Dakota, afternoon thunderstorm development will occur. Given the degree of instability, storms are expected to increase rapidly in coverage, with favorable deep-layer shear supporting rapid evolution into organized/rotating storms. Initial supercellular mode supports risk for very large hail and damaging wind gusts. With time, linear/potentially bowing clusters of storms are expected to evolve, and thus expect more widespread risk for very strong/destructive winds. As such, ENH risk is being introduced across portions of the Dakotas and into Minnesota -- for both the wind and the hail risk. Storms will continue well into the evening, with multiple rounds of storms affecting some areas before storms eventually weaken overnight as they approach the Upper Mississippi Valley. Less widespread risk is expected to evolve farther south across Nebraska -- both with storms developing near an eastward-moving trough, and with convection moving off the higher terrain to the west. ...The Rockies... As a weakening mid-level trough moves across Utah into Wyoming/Colorado, associated/large-scale ascent will support an increase in convective coverage through the afternoon and into the evening hours, as weak/high-based instability evolves in conjunction with diurnal heating. While deep-layer flow will not be particularly strong, the combination of 20 to 30 kt mid-level west-southwesterlies promoting longer-lived updrafts, and a deep mixed layer promoting potential for evaporative downdraft enhancement, suggests local risk for gusty/damaging winds. Some of the convection evolving over the higher terrain will spread into/across the High Plains, eventually encountering greater instability and posing more substantial wind risk (hence higher-probability risk across South Dakota and Nebraska). ...Southern Georgia/Florida... A weak/subtle ribbon of positive vorticity is forecast to shift southward across the western Atlantic and adjacent southeastern U.S. today, within weak northerly flow aloft on the eastern fringe of the dominant upper ridge. This will help to maintain a weak area of surface low pressure. In response, expect development of afternoon thunderstorms from southern Georgia southward into Florida, particularly focused near sea-breeze boundaries. As storms cluster/merge, and then shift southward with time, a few strong wind gusts can be expected, primarily during the afternoon and early evening hours before storms diurnally diminish. ..Goss/Squitieri.. 06/24/2022 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z 

Original News Source Link – National Weather Service

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