11PM Day 1 Convective Outlook for Saturday, January 3. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHEAST AND IN PARTS OF CALIFORNIA AND SOUTHWEST OREGON
SUMMARY
Isolated severe storms are possible across parts of the Southeast today. A few marginally severe storms will also be possible from the Sacramento and northern San Joaquin Valleys to coastal areas of northern California and southwest Oregon.
Southeast
A mid-level trough and an associated cold front will move across the southeastern U.S. today. Ahead of these features, a moist airmass will be in place from the central Gulf Coast eastward to southern Georgia and northern Florida. Surface dewpoints along this east-to-west corridor will be in the 60s F. Abundant cloud cover will hamper destabilization, with only weak instability expected in most areas. As large-scale ascent increases ahead of the approaching trough, scattered thunderstorms will develop along and ahead of the front in the early to mid afternoon. Although deep-layer shear will be strong enough for an isolated severe threat, relatively weak instability should keep any threat marginal. In areas that destabilize the most, a brief tornado or a few severe wind gusts will be possible.
California/Southwest Oregon
At mid-levels, a trough will approach the West Coast today, as an associated 60 to 80 knot jet streak moves into northern California. At the surface, a 986 mb low offshore will move toward the Pacific Northwest. From the coasts of central California to southwest Oregon, onshore flow will exist with surface dewpoints in the lower to mid 50s F. The low-level moisture will contribute to weak instability within an strongly sheared environment. This could be enough for marginally severe wind gusts and possibly a brief tornado. Further inland across the Sacramento and northern San Joaquin Valleys, a marginal tornado threat may also develop, especially as low-level strengthens during the evening.