textproduct: Columbia

WHAT HAS CHANGED

Scatter heavy showers expected again today with Wednesday trending a bit drier. Aviation discussion updated for 18z TAF.

KEY MESSAGES

- 1. Isolated to widely scattered showers and storms possible again today before chances become more spotty Wednesday. Warming temperatures and returning diurnal rain chances expected for the late week.

DISCUSSION

Key Message 1: Isolated to widely scattered showers and storms possible again today before chances become more spotty Wednesday. Warming temperatures and returning diurnal rain chances expected for the late week.

After multiple active days, things look to slowly start to wind down into the mid week with temperatures remaining cooler than normal. The diffuse frontal boundary that has contributed to the significant flash flooding and heavy rainfall the last few days continues to sag southward across the region. With much of our area now north of the surface boundary, and the consequent moisture convergence, convective coverage will be less intense than we have seen the last few days. PWAT's however still remain 2.0-2.5", along with skinny CAPE profiles, so highly efficient rainfall will still occur with any convection and such today. HREF guidance is largely in agreement, keeping the heaviest rainfall potential in the CSRA this afternoon with the LPMM showing spotty areas of near 2-4". The CSRA being the focus lines up with obs and HREF, with current obs as of 18z showing the weaker surface forcing and the general lack of convection from Columbia northeastward. Flash flood potential should be less notable than Monday but since areas like Evans and Martinez near Augusta received 4-6" yesterday, there are some sensitive areas that will not take even the high end amounts suggested from the LPMM.

The main change comes Wednesday with guidance trending a bit drier as the front remains south of the area and any forcing the mid level low retrogrades out of the region. The axis of PWAT's near 2.25" is expected to slowly pivot out of the FA toward the west, but PWAT's near 2" still may aid in bringing at least isolated activity during the afternoon. Heading into the late week, ensembles and global models depict an elongated upper ridge stretching from the central CONUS, toward the Ohio Valley. This may aid in bringing weak height rises to the FA as low level southerly to southwesterly flow brings back 850mb temps near the NAEFS 90th percentile. This setup should support warming temperatures near to just above normal late this week into the weekend. Moisture is expected to be fairly seasonable, thus cannot rule out typical diurnal convection chances, especially by the weekend.

AVIATION /18Z TUESDAY THROUGH SATURDAY/

Mainly VFR into tonight with restrictions becoming more likely near daybreak.

The low stratus continues to break out this afternoon as ceilings rise. Expect mainly VFR ceilings at the TAFs with some brief MVFR periodic MVFR ceilings at the Augusta terminals. Isolated shower and storms continue to bubble up on radar, so have included a PROB30 group for thunderstorms for this afternoon at all terminals. This activity is expected to wane as daytime heating diminishes. Overnight, guidance is suggesting fog and/or stratus to develop near daybreak and linger for several hours. There is some question in just how low the ceilings and/or visibilities get, however. Generally ENE winds from 5-10 kts can be expected this afternoon, becoming light and variable to calm overnight.

EXTENDED AVIATION OUTLOOK...The threat for restrictions eases for the end of the week into the upcoming weekend as conditions begin to dry out.

CAE WATCHES/WARNINGS/ADVISORIES

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