textproduct: Columbia

WHAT HAS CHANGED

A few showers or storms remain possible this afternoon, with the potential for them to be on the stronger side. Aviation discussion updated for the 18z TAFs.

KEY MESSAGES

- 1: Only a few storms expected mainly in the northern Midlands and Pee Dee, late this afternoon and evening, but these storms could be strong-severe.

- 2. Well above average temperatures expected to continue through Monday before a front moves in next week.

DISCUSSION

KEY MESSAGE 1: Only a few storms expected mainly in the northern Midlands and Pee Dee, late this afternoon and evening, but these storms could be strong-severe.

A low amplitude mid-level shortwave is currently moving over the Tennessee Valley. Expect this shortwave to continue pushing to the southeast through the afternoon and into this evening. An area of surface convergence is setting up across the area as expected, which looks weak, but may be just strong enough to spark a few showers or thunderstorms this afternoon, mainly for the northern Midlands into the PeeDee. Visible satellite imagery is showing some orographically induced cirrus; however, the latest images do show this cirrus deck is beginning to dissipate. The amount of instability will be determined by how much sunshine and heating can break through those clouds. Should enough sun peek out, surface CAPE values could approach the 700-1000 J/kg range late this afternoon. Latest forecast soundings continue to show an inverted V profile, indicating the potential for strong winds with any storms that do develop. Mid-level lapse rates at CLT as seen on ACARS soundings are currently around 6-7 degrees C/km, while forecast soundings show much of the same. This along with wetbulb zero heights around 9,000 ft indicate hail is also possible with any of the storms that may develop. Given the expected limited coverage of storms along with borderline parameters, the Marginal Risk for severe storms from the Storm Prediction Center seems reasonable.

KEY MESSAGE 2: Well above average temperatures expected to continue through Monday before a front moves in next week.

No notable changes in the forecast for late weekend and early next week as confidence remains high in well above average temperatures Sunday-Monday as upper ridging strengthens over the area. NAEFS mean continues to indicate 850mb temperatures rise to above the 99th to 99.5th percentile. While not expected to reach daily records through Sunday or Monday, blended guidance indicates highs will be 15 to 20 degrees above seasonal average, generally in the mid to upper 80s. A front is expected to move into the area late Monday, leading to a slight chance for showers and storms followed by temperatures closer to seasonal average for the middle of next week. The air mass behind the front is not forecast to be particularly cold, so frost or freeze are not expected through the end of next week.

Given the persistent low-level dry air and northwest winds, we are entering a period of increasing fire danger concerns given the lingering drought conditions. Wind speeds however are expected to remain below critical thresholds, with max wind gusts around 20 mph Sunday-Tuesday.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

VFR conditions expected over the 24hr forecast period.

High cirrus from the central Appalachians will continue to stream across the area through this afternoon. Can to rule out a few or scattered cumulus developing through sunset, but vfr conditions will remain. Guidance still indicating the potential for shower and thunderstorm development later this afternoon and early evening across the northern Midlands, but at this time it appears as if this activity will not impact cae/cub/ogb, so did not mention at any of those site. Biggest impact may be additional thicker cirrus, and/or a brief wind shift along a dying outflow boundary late this evening. No impacts at ags/dnl with any of this activity either. Wind will be northwesterly this afternoon before turning more west to southwest this evening. Wind speeds through sunset between 5-10 knots with gusts up to 16 knots still possible. Winds then should subside to 5 knots or less after 00z. Another increase to around 10 knots with higher gusts by 15z Sunday.

EXTENDED AVIATION OUTLOOK... A more significant cold front will move through on Monday, with a slightly better chance for restrictions. Overall, conditions will be most likely VFR for the next several days.

CAE WATCHES/WARNINGS/ADVISORIES

SC...None. GA...None.