textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated for 00z TAF issuance.

KEY MESSAGES

- 1. Light rainfall amounts possible late this week.

DISCUSSION

Key Message 1: Light rainfall amounts possible late this week.

An upper level low currently over the Upper Midwest and its associated cold front currently trailing into the Lower Mississippi Valley will continue to slowly slide eastward this week. As the trailing frontal boundary moves into the Deep South tomorrow the upper low will lift northward rapidly, limiting moisture advection to the area initially. The frontal boundary will slow down its eastward progression, helping to keep most of the shower activity to our west on Wednesday. Overnight on Wednesday and into Thursday, moisture advection strengthens over the Southeast as the surface ridge slips further offshore. This should promote isolated to scattered showers over the area ahead of the front.

A secondary upper trough will dig into the southern US Thursday and Friday, which will allow the front to progress further east before exiting the area Saturday. Weak convergence along the slow moving front and relatively low IVT values tend to favor only light rainfall amounts. In general from Thursday morning to Saturday morning only about 20 to 40 percent of ensemble members show greater than 0.50 inches of rainfall, favoring the western and northern FA. After this system pushes through, drier air is forecast to move back into the area once again.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

VFR conditions expected through the first half of the night then restrictions in stratus/fog expected during the predawn hours.

Easterly low level flow persists and continues to bring moisture into the region. Scattered VFR clouds expected this evening but most guidance is in agreement with some MVFR stratus developing after 08z impacting all terminals during the 09z-15z time frame. Some indications IFR cigs could develop around 12z so included a tempo group to handle possible IFR cigs from 10z-14z. Could see some MVFR vsbys in fog as well. A return to VFR cigs is expected after 16z. Winds should remain around 5 knots or less overnight before picking up to around 8 to 10 knots after 14z with direction shifting more southeasterly.

EXTENDED AVIATION OUTLOOK...Increasing chances for rain during the mid to late week may lead to some lower CIGS or VSBY restrictions.

CAE WATCHES/WARNINGS/ADVISORIES

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