textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated for 12Z TAFs.

KEY MESSAGES

- 1. Beautiful weather expected to continue through the end of this week.

- 2. Rain chances are forecast to increase this weekend, with an active pattern appearing possible into next week.

DISCUSSION

Key Message 1: Beautiful weather expected to continue through the end of this week. The persistently beautiful weather we have been experiencing for a week and a half now is forecast to continue into the end of this work week. Strong high pressure remains anchored at the surface to our northeast, funneling drier air into the area beneath strong subsidence aloft. This is forecast to slowly but surely shift as the week goes along, with at least the initial high forecast to shift eastward by Friday. This should be followed up by another strong surface high moving in this weekend, but the weather around that will likely be different that we are experiencing this work week. Moisture is forecast to slowly but surely increase over the next few days, with slightly warmer highs and lows expected by the end of this week (its modest - highs around 80 by Friday and lows in the low to mid 50s).

Key Message 2: Rain chances are forecast to increase this weekend, with an active pattern appearing possible into next week.

It would be difficult to really have weather quieter than what we have experienced the last week or so. We have seen persistent, dry high pressure remain entrenched in place across the eastern and southeastern CONUS in this period, ensuring the weather is benign and the temperatures are pristine. Confidence is increasing in active weather beginning again this weekend, with uncertainty extending well into next week. A complex upper level pattern is forecast to be in place by Saturday as a strong upper trough digs into the northeastern US. The subsidence on the backside of this is expected to yield another strong surface high pushing into the Mid-Atlantic region over the weekend. This will likely ridge down into the Carolinas again on Sat/Sun, with cooler temps (compared to Friday) returning again. Things get different after this as a complex, split-flow regime overspreads the southern and southwestern CONUS. A southern stream shortwave is forecast to shift eastward and approach by Sunday night, with moisture and isentropic lift increasing atop the surface ridge of high pressure as it does so. Rainfall will likely increase in coverage on Sunday as a result of this, with in-situ wedge conditions probable given the overall setup. Beyond this, there is a strong signal amongst deterministic and ensemble guidance that a robust longwave trough will emerge from the western US by the middle of next week and influence our weather. However, the ensemble clusters are showing wide spread, indicative of a low- confidence forecast even though it is somewhat in the medium range. IQR values of the LREF members are high next week, backing this idea up. So while the weather looks increasingly more active (it would be tough to be less active!) late this weekend and into next week, confidence is low on details beyond Sunday.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

VFR conditions expected through the period.

Skies remaining mostly clear with light and variable winds through sunrise this morning. Stratus development remains across eastern NC and is still pushing south and westward, similar to what the hrrr is showing this morning. There are a few clouds in the Pee Dee trying to form, but nothing widespread at this time. Guidance does show the stratus remaining east of the Midlands taf locations before it begins to slow and burn off after sunrise this morning. Winds are light, with a northerly component showing up on regional metar plot for most sites across the area. This light wind, and slightly stronger winds around 1kt should keep enough mixing in low-levels to help inhibit fog this morning. Based on all this, will continue with a vfr forecast at this time at all locations. Winds will increase to between 6-10 knots once better mixing starts around 15z, and may even see some gusts above 15 knots throughout the day and afternoon hours. Low-levels decouple towards 23z, and that will be when winds diminish back down to around 5 knots out of the northeast overnight.

EXTENDED AVIATION OUTLOOK...No significant aviation concerns through the end of the week. A few to scattered high VFR clouds may move in through Thursday due to onshore flow, but otherwise remaining dry. Restrictions may return moving into the weekend as moisture and rain chances begin to increase.

CAE WATCHES/WARNINGS/ADVISORIES

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