textproduct: Columbia

WHAT HAS CHANGED

Updated aviation discussion for 12z TAF.

KEY MESSAGES

- 1. High pressure and a cooler, drier air mass settles over the area today.

- 2. Showers and thunderstorms possible mid-week and this weekend.

DISCUSSION

Key Message 1: High pressure and a cooler and drier air mass settles over the area today.

High pressure over the eastern seaboard continues to ridge down the coast early this morning. Northeast flow has ushered in some low level moisture resulting in stratus, and also drier surface air with dewpoints beginning to fall into the 40s. Generally expecting this trend to continue through the day, though the stratus deck should clear out by mid to late morning. PWAT should continue to drop as well, ending up below 0.5" by this afternoon. No precip expected today with the ridge building overhead and temps reaching the mid 70s. The SCFC Burn Ban remains in effect with daytime RH values likely falling into the low 30s, and northeast winds may be breezy at times.

Key Message 2: Showers and thunderstorms possible mid-week and this weekend.

PWATs increase again tonight into Tuesday to above 1", with surface high pressure generally remaining in place. However, a shortwave passing through the area may fire off a few morning showers or thunderstorms. At this point, the overall severe threat is low and the bulk of the rain should be confined to the western and northern Midlands. Additional energy is progged to move through the region Wednesday as the synoptic pattern shifts and ridging overhead begins to flatten out. Moderate wind shear coupled with sufficient instability hints at the potential for low-end storm organization, with an overall decent chance of rainfall Wednesday into Wednesday night. Rainfall amounts between one third and one half inch are looking more likely, with the NAEFS IVT remaining around the 90th percentile of climatology. Additional shortwaves are then forecast to move through periodically into this weekend, continuing at least slight chances for rain. The next big slug of moisture doesn't arrive until Saturday, so accumulations until then will likely be meager.

AVIATION /12Z MONDAY THROUGH FRIDAY/

Periods of MVFR ceilings continue this morning before giving way to VFR conditions by the late morning to early afternoon.

MVFR stratus continues this morning across the TAF sites as the deck continues to build southward. Winds also remain out of the northeast between 6-10 kts. These conditions are expected to continue through 15-17z before stratus mixes out, giving way to SCT to BKN VFR cumulus early this afternoon. Skies then are expected to gradually clear through the afternoon with passing cirrus expected the remainder of the TAF period. Winds generally remain out of the northeast around 6-10 kts through this afternoon, but do become a bit lighter and easterly this evening into tonight. Tonight, winds may become light and variable ahead of a line of showers, where there is at least a minor indication more stratus could be possible mainly in the CSRA, but confidence is too low to add into the TAF at the moment.

EXTENDED AVIATION OUTLOOK... A broken line of showers should move in Tuesday during the late morning to early afternoon, where patchy restrictions could be possible. Periods of restrictions then are possible into the mid to late week with a more unsettled pattern continuing.

CAE WATCHES/WARNINGS/ADVISORIES

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