textproduct: Columbia

WHAT HAS CHANGED

The potential for flash flooding continues today. Another period of more widespread rainfall is expected to develop later today through early Monday as a front pushes through the region. The focus of heavier rainfall shifts southward into the central Midlands through the day, then into the CSRA and southern Midlands late this afternoon and tonight. Aviation discussion updated for 12z TAFs.

KEY MESSAGES

- 1. Slow moving front and plenty of moisture will bring periods of rain, along with an increased risk for flash flooding.

- 2. Cooler and drier conditions expected to move in Monday afternoon, lasting through much of the week.

DISCUSSION

KEY MESSAGE 1: Slow moving front and plenty of moisture will bring periods of rain, along with an increased risk for flash flooding.

This morning through early Monday: Little change to the latest forecast at this time. Surface front has pushed into the central Midlands this morning, and will continue to slowly push southward today and into Monday morning. In addition, both the 500 mb and 850 mb winds remain out of the southwest ahead of an approaching upper trough, at least into later tonight. Latest moisture analysis still showing pwat values between 2.0 to 2.3 inches this morning. With the above wind pattern still bringing plenty of Gulf moisture northward today into tonight, most of the guidance shows pwats remaining well above 2 inches at least into Monday morning. Best shortwave energy moves through later this afternoon and into tonight, and this should be the most favorable time period for more widespread heavy rain potential to setup across the area. Overall, this environment is expected to remain conducive for instances of flash flooding. Heaviest rain after sunrise this morning should be along and just south of the surface front, with the axis of heavy rain then slowly shifting southward this afternoon and into tonight.

Key Message 2: Cooler and drier conditions expected to move in Monday afternoon, lasting through much of the week.

Once the surface front pushes south of the area by Monday afternoon, much drier air will finally begin moving into the region from the north. Pwat values by Monday evening will be dropping to below 1.5 inches across the southern forecast area, while even drier air with pwats below 0.75 inches will be pushing into the northern half of the forecast area. That drier air will continue pushing southward Monday night into Tuesday. Temperatures drop slightly below normal through mid-week, then return to near normal towards the end of the week. Rain chances not expected to return until possibly at some point next weekend.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

Restrictions expected today and into Monday.

Little change to previous thinking. With plenty of low-level moisture across the region, and a cold front slowly pushing southward through the forecast area through the period, all guidance is fairly consistent with bringing ifr/lifr ceiling restrictions to all taf locations today. Latest metars are already showing many areas already ifr, with only a few exceptions. Will generally be keeping all taf locations ifr/lifr through the end of the 24 hours taf period. Periods of showers are also expected, with some visibility restrictions also tossed in with the heavier shower activity. Outside of showers, periods of light drizzle may be encountered. All in all, will not be a good period for general aviation flying.

EXTENDED AVIATION OUTLOOK...Restrictions possible Monday morning, then drier air begins to filter in Monday afternoon, with improving conditions possible by that time.

CAE WATCHES/WARNINGS/ADVISORIES

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