Administrators NorthGeorgiaWX Posted December 18, 2023 Administrators Share Posted December 18, 2023 SPC 1200Z Day 1 Outlook Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1159 PM CST Sun Dec 17 2023 Valid 181200Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF COASTAL SOUTHERN NEW ENGLAND... ...SUMMARY... A damaging gust or two is possible from the eastern shore of New Jersey into southern New England this morning and afternoon. A few isolated lightning flashes are possible along the northern/central California coast. ...Synopsis... A broad mid-level trough will amplify across the East Coast as a 500 mb jet max overspreads portions of southern New England today, supporting the rapid northeastward ejection of a 986 mb surface low into Quebec by evening. Intense low-level wind fields will be in place ahead of the surface low, supporting conditional damaging gust potential with any storms that can root into an unstable boundary layer. Meanwhile, another trough will impinge on the West Coast, supporting appreciable rainfall accumulations and at least isolated thunderstorms. ...Portions of southern New England... The surface low will overspread southern New England, immediately preceded by a 70+ kt 850 mb southerly jet. Tropospheric flow will be unidirectional, supporting straight hodographs. 6 C/km lapse rates above 850 mb may boost MUCAPE to 500 J/kg, which will support at least elevated convection. The primary mitigating factor for a robust severe thunderstorm wind threat is the likelihood for a stable boundary layer, which should dampen downward momentum transport in stronger storm cores. Modified forecast soundings suggest surface temperatures would need to reach the mid 60s F amid 60+ F dewpoints to support 100+ J/kg SBCAPE. However, ensemble guidance suggests that maximum high surface temperatures will struggle to reach the lower 60s F, casting doubt on the potential for organized severe storms. Nonetheless, the intense low-level wind fields suggest that any downward momentum transport within thunderstorm cores that can occur may support a damaging gust threat during the late morning and afternoon hours. A Category 1/Marginal Risk has been maintained for coastal portions of southern New England to address the conditional damaging gust threat. ..Squitieri/Darrow.. 12/18/2023 Read more View the full article Quote Link to comment Share on other sites More sharing options...
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