Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0800 AM CDT Sun Apr 30 2017 Valid 301300Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF LA/MS/AL... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE GULF COAST STATES TO MIDWEST... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE GULF COAST STATES TO MIDWEST AND NORTHERN APPALACHIANS... ...SUMMARY... Severe thunderstorms capable of damaging winds and tornadoes are expected today into tonight, especially across the central Gulf Coast States. Other severe storms could occur as far north as the Midwest and southern Great Lakes region. ...Lower MS River Valley/Gulf Coast States... A linearly organized broken cluster of storms is ongoing across along the LA/MS vicinity, where multiple tornadoes have occurred in the pre-dawn hours, and extends southward into south-central LA early this morning. These storms will continue to spread east-northeastward through the morning/afternoon hours. Although high-level winds are not overly strong per regional 12Z soundings, a modest but strengthening westerly component aloft in conjunction with strong low-level shear, including modestly backed southeasterly surface winds, will continue to support a mixed convective mode including embedded supercells/mesovortices capable of tornadoes and damaging winds. A strong tornado cannot be ruled out. See Mesoscale Discussion 611 for additional short-term details. The tornado/damaging wind risk should shift into portions of AL by this afternoon, including the possibility of some regenerative development later this afternoon into early evening particularly on the southern flank of convection/possible outflow amidst moist confluent low-level flow. ...Midwest/southern Great Lakes and Ohio Valley... Questions exist regarding the extensiveness and likelihood of appreciable destabilization later today in a scenario that appears otherwise very favorable for severe thunderstorms given ample deep-layer/low-level shear. These uncertainties are related to extensive convection ongoing early today across the middle MS River Valley and lower OH Valley, with an east/northeastward-moving MCV also a factor across eastern IL/northern IN today. Ahead of the cold front, gradual destabilization should occur into this afternoon along the southern/eastern fringes of ongoing precipitation and residual outflows, with the possibility of least some damaging wind/marginally severe hail risk developing this afternoon. As the upstream trough approaches the region and surface low spreads northeastward and deepens, at least a narrow corridor of modest destabilization could allow for late afternoon and evening increase in fast-moving storms capable of a severe risk. ..Guyer/Mosier.. 04/30/2017Read more
from SPC Forecast Products http://ift.tt/rATNzD
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