textproduct: Columbia

WHAT HAS CHANGED

The severe thunderstorm threat has ended for this evening. Aviation discussion updated for 00z TAFs.

KEY MESSAGES

- 1. Scattered storms each afternoon through Monday with heavy rain and frequent lightning. Damaging wind gusts possible in strongest storms, especially tomorrow.

- 2. Hot and humid this weekend with cooler temperatures next week.

DISCUSSION

Key Message 1: Scattered storms each afternoon through Monday with heavy rain and frequent lightning. Damaging wind gusts possible in strongest storms, especially tomorrow.

An active afternoon/early evening with severe weather has wound down as only lingering showers persist near the western CSRA and far southeastern Midlands. Heading into the overnight, cannot rule out a few isolated showers developing in the moist airmass with the upper low nearing the region, but confidence in these developing is rather low. Attention will then turn toward the severe thunderstorm risk tomorrow afternoon/evening.

Tomorrow, an upper low approaches the area with a fairly similar environment to that of today expected with strong destabilization and potential for wet microbursts once again with a slight risk continuing across much of the forecast area. Depending on the evolution of convection over the next 24 to 48 hours, we may need to monitor some spots for potential flash flooding, although storm motion should be sufficient to prevent significant flooding concerns outside of any training.

Monday, a cold front drops towards the forecast area, providing additional forcing for convection, although lingering storms Sunday night into Monday morning may prevent as significant destabilization with cooler temperatures expected. Will need to continue to monitor a potential flash flood threat, keeping in mind this will depend significant on antecedent conditions from Saturday and Sunday. In general, ensemble means have trended much slower with the advancement of dry air into the area next week and conditions may remain unsettled into the middle of next week with ensemble means keeping PWATs greater than 2 inches through Tuesday and with only a somewhat marginal decrease Wednesday into Thursday.

Key Message 2: Hot and humid this weekend with cooler temperatures next week.

Hot and humid conditions expected tomorrow with max temperatures likely reached early afternoon for many locations before the onset of significant convection. Heat indices likely still rising into the triple digits Sunday with any decrease in temperatures offset by the increase in dew points. Blended guidance has creeped up slightly in the last several runs on temperatures for Monday and Tuesday as increasing confidence in the front lingering near the area, preventing a significantly cooler air mass from moving in with a decent temperature gradient expected from north to south. Still expect below average temperatures Monday and Tuesday, which feels like a win. This will likely be short lived, however, as the air mass likely recovers for the second half of the week with temperatures near to slightly above average.

AVIATION /00Z SUNDAY THROUGH THURSDAY/

VFR conditions are expected to persist outside of thunderstorm activity that returns Sunday afternoon.

Only a few lingering showers across the region this evening with the severe threat ended and thunderstorms now offshore. Light winds and convective cloud debris will remain through the night, with CIGs likely between 12kft and 20kft. Guidance is not keen on VSBY restrictions Sunday morning likely due to some ongoing boundary layer mixing, so have not included them in the TAFs at this time. Widespread cumulus around 5kft should redevelop by 15z Sunday morning. Another round of strong thunderstorms is then expected on Sunday afternoon, so have included VCTS and a PROB30 for -TSRA at all terminals. Winds could again gust to 30-40 kts in the strongest thunderstorms. Outside of convective gusts though, surface winds should be less than 10 kts from the SW-NW.

EXTENDED AVIATION OUTLOOK...A good chance for afternoon showers and thunderstorms with associated restrictions is expected into early next week. There is potential for VSBY restrictions in fog Monday morning behind a frontal passage.

CAE WATCHES/WARNINGS/ADVISORIES

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