textproduct: Columbia

WHAT HAS CHANGED

Rain chances have increased Thursday and Friday, but overall amounts are expected to be light. Aviation discussion updated for 18z 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 and associated cold front currently in the Ark-LA-Tex region will 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 /18Z TUESDAY THROUGH SUNDAY/

VFR conditions prevailing through this evening. Another round of restrictions possible late tonight into Wednesday morning.

Low level easterly flow continues to bring moisture into the region, with satellite imagery showing the development of SCT- BKN cumulus across the region. Cloud bases are generally between 3-5kft MSL. Surface winds should remain around 5 to 10 knots from the east- northeast this afternoon. Winds should weaken this evening with speeds dropping below 5 kts at CAE/CUB/OGB/AGS, but possibly remaining elevated at DNL/AIK. Looking ahead to tonight, guidance continues to indicate potential for another round of CIG and VSBY restrictions, potentially into the IFR range. Added a TEMPO group between 10 and 14Z for potential IFR cloud bases. There is a low chance (15-30%) of LIFR ceilings around 12Z, but low confidence right now.

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.