textproduct: Columbia

WHAT HAS CHANGED

Minimal change to the forecast as a trend toward a dry frontal passage continues. Elevated fire weather conditions behind the cold front on Thursday. Aviation discussion updated for 18z TAFs.

KEY MESSAGES

- 1. A cold front moves through tonight where a stray shower cannot be ruled out.

- 2. Potential for increased fire weather conditions Thursday behind cold front.

- 3. Dry conditions are expected with temperatures warming above normal this weekend and early next week.

DISCUSSION

Key Message 1: A cold front moves through tonight where a stray shower cannot be ruled out.

Mid-level analysis shows broad toughing over the eastern CONUS with an embedded shortwave swinging across the Appalachians. A weak surface cold front will approach and move through the area tonight into Thursday morning. Moisture remains limited ahead of the boundary, with PWAT values generally around 1" across much of the FA. Forcing and associated lift with the front will be weak, and most locations should remain dry as the system is somewhat moisture starved. That said, the latest HREF, REFS, and their respective members indicate that a stray shower cannot be completely ruled out mainly in the northern Midlands toward the Pee Dee, but mostly dry conditions should prevail. Behind the front, winds will turn northerly as a notably drier air mass filters into the region.

Key Message 2: Potential for increased fire weather conditions Thursday behind cold front.

Very dry air is expected to move in behind the cold front tonight. As low level flow becomes increasingly northwesterly to northerly, solid mixing combined with down sloping may aid in dropping dew points a bit further than currently modeled Thursday. Latest REFS probabilities continue to show a 50-70% chance of surface dew points dropping below 35F Thursday afternoon. There is increasing confidence that minimum RH values will near if not fall below critical values for much of the FA. In addition, a fairly tight pressure gradient behind the cold front could bring wind gusts up to 15-20 mph through early Thursday afternoon before diminishing. Luckily, winds should remain weak enough to not need a fire weather product, but a lack of rainfall with this front, drought conditions, and a very dry air mass moving in should bring elevated fire weather conditions and concerns through the late afternoon hours.

Key Message 3: Dry conditions are expected with temperatures warming above normal this weekend and early next week.

Upper toughing will linger in the area through Friday, maintaining near-normal temperatures and dry conditions. Ensemble and global guidance then indicate an upper ridge working into the Southeast this weekend with a strengthening Bermuda high. This pattern is expected to persist into at least early next week before potentially breaking down some during the mid week. Persistent southwesterly to southerly flow is expected to bring in warming temperatures and increase moisture across the state. Afternoon highs are forecast to reach the 90s by Saturday and remain into the early part of next week. EC EFI values remain between 0.7-0.8 through Tuesday, aiding in increasing confidence in this period of above normal temperatures. The airmass should remain fairly dry initially, but by Sunday there is some indication that as the FA finds itself more on the western periphery of the upper ridge and Bermuda high, increasing moisture and seasonable instability could bring spotty diurnal rain chances.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

VFR Conditions Expected to Continue....

Afternoon radar imagery shows a band of lights showers continuing across the southeastern Midlands. While they have spent much of the day in the vicinity of OGB, they are not expected to impact operations there and should eventually pass to the east. Ceilings continue to rise at the terminals this afternoon with all sites now reporting VFR conditions, which should continue for the entire TAF period. A dry cold front will approach this afternoon and should result in winds shifting to the southwest or west. For tonight, the front will move through the area with another wind shift to the northwest.

EXTENDED AVIATION OUTLOOK...Widespread restrictions unlikely through Sunday.

CAE WATCHES/WARNINGS/ADVISORIES

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