textproduct: Columbia

SYNOPSIS

High pressure brings cool and dry conditions through Thursday. The next storm system approaches late Thursday or Thursday night with another period of moderate to potentially heavy rainfall on Friday. Unsettled weather may continue into the weekend.

NEAR TERM /THROUGH TONIGHT/

Key message(s):

- Cool and dry conditions today.

Dry high pressure will be centered north of the region. Day starts off with a good amount of low cloud cover due to stratus across the area. These clouds will be thinning by late morning across the Midlands, but may hold on until the early afternoon across much of the CSRA. So eventually by late this afternoon some sunshine is expected to be seen before the day is over. Weak cold advection though will still be across the region, and this combined with the morning clouds will keep afternoon highs mainly from around 50 north, to the middle 50s south. Dry weather conditions remain into the overnight hours. With somewhat ideal radiational cooling conditions due to much less clouds, dry air, and light winds, temperatures will be dropping down to around the freezing mark for most areas.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/

Key message(s):

- Cool temperatures continue, with dry conditions on Thursday. - Rain spreads over the region for Friday, potentially moderate to heavy at times.

Thursday and Thursday night: Surface high pressure is forecast to pass through the Mid-Atlantic during the day. Meanwhile, southwesterly flow aloft is expected to persist, allowing for an increase in moisture through the day. Shortwave energy within the larger scale flow along with a developing surface low begin moving toward the area. However, any rain activity is anticipated to hold off until overnight, with better chances closer to daybreak. In addition to the increased moisture on Thursday, afternoon highs are forecast to be a few degrees warmer than Wednesday.

Friday and Friday night: The surface low and upper shortwave energy continue to move from the Gulf states and through the Southeast through the day, allowing for rainfall to spread across the region. This system looks similar to the system that just moved through on Tuesday. PWAT values are forecast to increase to the 1.3-1.6" range, leading to the potential of pockets of moderate to heavier rain. Ensemble guidance shows a moderately high chance (50-70%) of rainfall amounts over an inch by early Saturday morning. There remains some difference in the location among the ensemble models as well as LREF clusters. Nonetheless, confidence is high (70-90%) that the forecast area will receive another round of beneficial rain. Temperatures are forecast to be cooler once again with the ongoing rainfall.

LONG TERM /SATURDAY THROUGH TUESDAY/

Key message(s):

- Chances for rain continue through the weekend, with cooler than average temperatures.

A trailing frontal boundary is forecast to develop as the surface low continues moving northeast. It is anticipated to be nearly parallel to the upper level flow, so it is unlikely to move too much through the weekend. Multiple shortwaves are forecast to move through the area through the weekend and potentially into early next week, leading to continued chances for rain showers. Guidance is hinting at a sharper trough moving into the area early in the week, which could aid in pushing out the boundary and moisture by midweek.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

MVFR restrictions through late morning or early afternoon before a return to vfr occurs.

Satellite continues to show widespread mvfr stratus deck across all taf locations this morning. Clouds expected to remain through much of the morning hours before eventually rising and beginning to scatter out some through early afternoon. Improvement to vfr should occur over the Midlands sites of cae/cub near issuance time, then at ogb by mid to late morning, and finally into the CSRA by early afternoon. VFR conditions then expected from late afternoon and into the overnight hours. With good radiational cooling conditions tonight, can not rule out some patchy fog near rivers/lakes. Winds will be out of the northeast around 5 knots early in the day, then becoming light and variable by late morning. As low-levels decouple tonight, wind should go calm at all sites.

EXTENDED AVIATION OUTLOOK...Mainly VFR Thursday. Restrictions possible again late in the week and this weekend, particularly Thursday night through at least Saturday morning.

CAE WATCHES/WARNINGS/ADVISORIES

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