textproduct: Columbia

WHAT HAS CHANGED

00Z aviation forecast updated.

KEY MESSAGES

- 1) Breezy winds and increasing rain chances mid to late week.

DISCUSSION

KEY MESSAGE #1: Breezy winds and increasing rain chances mid to late week.

High pressure shifts offshore tomorrow with increasing WSW low level flow as a front approaches the area from the northwest. This will lead to increasing moisture as well as strengthening winds. NAEFS mean continues to indicate that 850mb winds will be above the 90th percentile (around 30-40 knots) over the area both Wednesday and Thursday, although mixing will not be ideal, this will still lead to breezy winds both days. An approaching mid-level trough will shift the front into the area, but with the front parallel to the overall mid level flow, it is expected to move slowly through the area. Ensembles have generally trended wetter over the forecast, with the trough deepening to the west of the area. As a result, both the GEFS and ECMWF ensemble means have a longer period of PWATs near 200 percent of normal Thursday into Friday morning. PoPs remain high during this period but QPF amounts generally have trended upwards. While there remains uncertainty as to rainfall totals for any one location in the area due to uncertainty of the exact location where the front will stall, increasing confidence that a heavier rain band will develop somewhere within the forecast area with highest rainfall amounts of around 2 inches possible (10-20% probability of greater than 2 inches within the blend).

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

VFR conditions are expected to continue with breezy winds on Wednesday.

SCT to BKN cirrus continue to stream into the region as surface winds are out of the southwest between 4-8 kts. Winds should remain elevated tonight as a strong 30-35 kt LLJ sets up over the region. This brings borderline values for reaching LLWS criteria, but at this time, LLWS is not in the TAF to observe how the LLJ tonight progresses and the degree in which surface winds remain elevated. BKN cirrus are expected to remain in place on Wednesday with some gradual lowering of the deck through the day, but VFR conditions likely remain. Southwest winds pick up quickly after 14-16z to 10-15 kts with gusts to 20-25 kts likely much of the day. These gusts slightly weaken during the evening but likely remain breezy through the end of the TAF period. EXTENDED AVIATION OUTLOOK...The next chance at widespread restrictions and rain will move in through the day Thursday, continuing into Friday as a front approaches the area.

CAE WATCHES/WARNINGS/ADVISORIES

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