SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0130 PM CST Fri Dec 25 2020 Valid 252000Z - 261200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The risk for severe thunderstorms is negligible through early Saturday. ...Discussion... Very little change is required to the ongoing outlook at this time, aside from a slight trim on the western fringe of the New England thunder area, to account for eastward translation of the front. Otherwise, potential for a few lightning strikes will continue across Down East Maine through this evening, and over portions of coastal Oregon and adjacent northern California this evening and tonight. ..Goss.. 12/25/2020 .PREV DISCUSSION... /ISSUED 1008 AM CST Fri Dec 25 2020/ ...Southwest OR and northwest CA... A shortwave trough will move inland across the Pacific Northwest this evening through tonight. Cooling mid-level temperatures and steepening low to mid-level lapse rates will support scant buoyancy west of the surface cold front. Scattered low-topped convection within this onshore flow regime may yield isolated lightning flashes after 00Z through tonight. Small hail is possible in the deeper updrafts with moderate speed shear in a nearly unidirectional southwesterly wind profile, which may result in effective bulk values approaching 30 kts. ...Southern ME... A narrow low-topped convective line recently weakened across eastern MA as low-level convergence has diminished along this leading cold front while focusing back west in eastern NY along a trailing frontal surge. Nevertheless, guidance still indicates scant elevated buoyancy from parcels rooted between 850-700 mb may persist within the warm conveyor region and yield a threat for very isolated lightning flashes through about 21Z.
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