textproduct: Columbia

WHAT HAS CHANGED

Forecast for this evening and aviation discussion updated for 00Z TAFs.

KEY MESSAGES

- 1. Isolated showers and storms this evening, scattered showers likely early Sunday.

- 2. Temperatures continue to be well above normal through at least the mid week next week. - 3. Chances for diurnal showers/storms continue into the early week, with a few strong storms possible Sunday afternoon and evening.

DISCUSSION

KEY MESSAGE #1: Isolated showers and storms this evening, scattered showers likely early Sunday.

Some scattered showers and thunderstorms continue to wander across the Midlands and CSRA this evening. Surface based instability is still over 1000 J/kg and some weak shear is helping briefly organize any thunderstorms. So some gusty winds and some thunder are possible in these isolated storms through 8pm or so before diurnal heating cuts off. The decaying MCS and squall line, currently in MS-AL, will eventually push into our region late tonight. While surface instability will drop off, some elevated instability will remain, so a some weak thunderstorms are possible as this decaying line moves through. Best chance overnight for showers looks to be between 3am-7am.

KEY MESSAGE #2: Temperatures continue to be well above normal through at least the mid week next week.

The strong mid to upper ridge sitting over the region is forecast to remain over the Southeast for the next several days. However, guidance suggests that the trough currently over the Great Plains moves eastward today into Sunday, temporarily flattening the ridge out somewhat. Meanwhile, the southern portion of the aforementioned trough is forecast to become a closed low and drift over Baja California. Eventually, this feature is expected to eject eastward, allowing the ridge over the Southeast to restrengthen. Despite the flattening of the ridge the next couple of days, geopotential heights are still forecast to be anomalously high over the region. Therefore, the temperatures are forecast to remain well above normal. With the ridge restrengthening later in the forecast period, temperatures bump up even higher fore midweek ahead of the next potential trough. Ensemble spreads through midweek remain rather small, leading to a higher confidence in these high temps. The spread increases quite a bit late in the week, leading to more uncertainty.

KEY MESSAGE #3: Chance of diurnal showers into next week, with a few strong storms possible Sunday afternoon and evening.

The trough mentioned in Key Message #2 is expected to push a front toward the area for Sunday, but it is forecast to become washed out to some extent. That said, there should be enough diurnal heating and forcing in the area to produce more coverage of showers and storms than Saturday. The threat for severe weather remains low as the best dynamics and shear are expected to be north of the area. However, a stronger storm cannot be ruled out, especially near the Charlotte metro into the PeeDee region; storms overperformed today, so guidance is not doing a great job resolving this highly anomalous and relatively unstable airmass. With the residual heat and moisture, chances for diurnal showers continues into the early part of the week. Due to the lack of a forcing mechanism, coverage is anticipated to be isolated, however. A frontal boundary late in the week could bring higher chances for rainfall to the area.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

VFR conditions expected into the overnight hours then stratus expected to redevelop and bring possible restrictions. Some additional showers expected during the predawn hours and again Sunday afternoon.

Regional radar shows a line of showers and embedded thunderstorms over TN/AL which will push east overnight ahead of a weak cold front but weaken as they move into our area. Some showers may impact terminals except OGB during the 05z-10z time frame before dissipating. Otherwise, the environment remains generally unchanged with moist southerly flow ahead of the approaching front and expect another round of stratus favoring the eastern Midlands and impacting OGB with lower confidence at the other terminals (will include a tempo there). Stratus should dissipate by mid morning (14z-15z) and a VFR ceiling expected through the day as the front moves into the area and becomes diffuse. Scattered showers and possible thunderstorms after 17z but confidence in impacts at terminals is limited.

EXTENDED AVIATION OUTLOOK...Patchy morning fog remains possible each day. Increased shower and storm chances expected into early next week.

CAE WATCHES/WARNINGS/ADVISORIES

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