SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0145 PM CST Wed Jan 04 2023 Valid 042000Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF NORTHERN FL AND SOUTHEAST GA AS WELL AS EASTERN NC AND FAR SOUTHEAST VA... ...SUMMARY... Strong to severe thunderstorms are forecast today over portions of the Southeast and Mid-Atlantic. Damaging gusts and a couple of tornadoes are possible, mainly over parts of Georgia, the Florida Panhandle and the Carolinas. ...20Z Update... ...Southeast into the Mid-Atlantic... A broken line of showers and thunderstorms extends from eastern NC southwestward into northern FL. Strongest storms within this line are currently located over northern FL. Warm and moist conditions exist ahead of this line, supporting the potential for strong to severe storms capable of hail, damaging wind gusts, and/or brief tornadoes. Farther north, temperatures have warmed into mid 70s across northeast NC, helping to support moderate buoyancy ahead of an arcing line of thunderstorms. A few strong to severe storms are possible within this line as it continue northeastward through the remainder of northeast NC and into far southeast VA. Primary hazards with these storms are damaging wind gusts and a tornado or two. ...Central California Coast... Convectively enhanced damaging wind gusts are still possible tonight across the central CA coast as a strong frontal band moves onshore. Most recent guidance indicates the band will likely impact the region from 02Z to 09Z. ..Mosier.. 01/04/2023 .PREV DISCUSSION... /ISSUED 1027 AM CST Wed Jan 04 2023/ ...Southeast into the Mid-Atlantic... A midlevel cyclone (evident in water vapor imagery) currently centered over southern MN will move slowly east-southeastward into southern WI through the period. Peripheral to this cyclone, broad/enhanced cyclonic flow aloft will persist across the eastern CONUS, while an embedded southwesterly midlevel speed max lifts northeastward from the TN Valley toward the Northeast and weakens with time. At the surface, a cold front, currently extending from the Ohio Valley south-southwestward into the central Gulf Coast, will advance eastward toward the East Coast. Ahead of the cold front, a QLCS extending from SC south-southwestward into the FL Panhandle will continue tracking eastward this afternoon. Upper 60s boundary-layer dewpoints and pockets of diurnal heating/destabilization ahead of the convective line will continue to support surface-based inflow for this activity as it continues toward the coast. And, 40-50 kt of effective shear oriented mostly parallel to the leading-edge gust front will favor a continued organized/linear mode with a primary risk of damaging gusts and perhaps a couple of embedded mesovortex tornadoes. The tornado and damaging-wind risk should be maximized with any north-south-oriented segments of the line, where deep-layer flow/shear will be more favorably oriented to the gust front. For details regarding the ongoing severe risk over this area, refer to Tornado Watch 13 and Mesoscale Discussion 34. Farther north into eastern North Carolina, additional thunderstorm development is underway along the eastern edge of widespread cloud coverage extending across western North Carolina. During the next couple of hours, continued diurnal destabilization across the warm sector will yield moderate instability amid strong deep-layer southwesterly flow, with 45-55 kt of effective shear and modest low-level hodograph curvature. As a result, storms should gradually intensify as they intercept this favorable environment this afternoon. A mixed-mode, consisting of supercell clusters and line segments, will pose a risk of locally damaging gusts and a couple of tornadoes this afternoon. For more details, refer to Tornado Watch 14. ...California Coast... While cloud coverage will generally limit diurnal heating along the CA coast today, at least pockets of heating/mixing amid lower/middle 50s dewpoints should yield weak surface-based instability by the evening/overnight hours. Strong DCVA ahead of an approaching midlevel trough and a strengthening low-level jet should aid isolated thunderstorm development during the evening/overnight hours. 40+ kt of deep-layer shear should support a loosely organized frontal band of convection capable of strong to locally damaging gusts.
