textproduct: Columbia

WHAT HAS CHANGED

A slightly lower chance for rain on Tuesday than previous forecast. Aviation discussion updated for the 18z TAFs.

KEY MESSAGES

- 1. Elevated fire weather concerns and periodic smoke impacts will persist through Friday.

- 2. Rain chances increase this weekend into early next week, but meaningful drought relief remains uncertain.

DISCUSSION

Key Message 1: Elevated fire weather concerns and periodic smoke impacts will persist through Friday.

A dry air mass persists over the region with relative humidity values currently in the 20-30 percent range, which potentially could drop below 20 percent briefly yet this afternoon. RH values are likely to drop below 30 percent Friday for many locations. Much of the area remains in severe to extreme drought. Despite the lack of stronger winds, the combination of low RH and dry fuels result in elevated fire danger each afternoon. Latest observations and HRRR smoke guidance once indicate that a lull in smoke over the area can be expected into tonight, but could settle back into the region overnight into the early morning hours Friday as winds translate smoke from wildfires across the region. South Carolina Department of Environmental Services issued an Air Quality Alert for today for the CSRA and Midlands of South Carolina. In addition, the SC Forestry Commission continues a Burn Ban until further notice.

Key Message 2: Rain chances increase this weekend into early next week, but meaningful drought relief remains uncertain.

A more unsettled pattern is expected to develop as the upper ridge breaks down and the Bermuda high weakens. HREF members continue to indicate some isolated shower activity tomorrow. However, looking at forecast soundings, even with a bit of an increase in PWATs, significant amounts of low level dry air will limit the potential of any rain from reaching the surface. Higher chances for showers and potential thunderstorms arrive on Saturday associated with a cold front, although model consensus is that this system will be relatively progressive, limiting total rainfall. Isolated chances for additional showers Sunday and Monday with another front likely approaching Tuesday leading to slightly higher chances for rainfall. While there looks to be several chances for rain over the coming days, the drought is likely not going to be significantly reduced anytime soon as the latest runs of the GEFS and EC ensemble continue to show just a meager chances of greater than an inch of rain through the next 7 days; 20-30% and less than 10%, respectively. It will take much more rain than that to eliminate the drought across the area.

AVIATION /18Z THURSDAY THROUGH MONDAY/

VFR conditions are expected to continue, but periods of haze from wildfire smoke remain possible this afternoon.

5-8 kt southwesterly winds continue this afternoon as FEW to SCT cumulus develop with lingering wildfire smoke, though visibilities across the area are generally greater than 6SM. These conditions continue the remainder of the day, where brief periods with lower than 6SM visibility from wildfire smoke will be possible, but this is seeming a bit more unlikely given recent HRRR near surface smoke runs. Tonight, winds become light and a bit more southerly as a 25-30 kt LLJ is shown in BUFKIT models. Have left out LLWS at this time with surface winds near 3-5 kts, but this may need to be included if surface winds end up a bit weaker or the LLJ is stronger than modeled. For Friday, dry conditions prevail with light winds out of the southwest once again and SCT cumulus developing during the afternoon. The 12z HRRR near surface smoke run does depict the potential for reduced visibilities again near the end of the period but confidence is too low to add into the TAF at this time.

EXTENDED AVIATION OUTLOOK...Rain chances increase Saturday afternoon and evening, which may introduce periods of restrictions, but confidence in coverage remains low. Rain chances may continue into Sunday as well.

CAE WATCHES/WARNINGS/ADVISORIES

SC...Air Quality Alert until 8 PM EDT this evening for SCZ018- 020>022-025>031-035-037-038-041-135>137. GA...Air Quality Alert until 8 PM EDT this evening for GAZ064-065.