textproduct: Columbia

WHAT HAS CHANGED

Split up Key Messages to address the potential rainfall this upcoming weekend. Aviation discussion updated for 00z TAFs.

KEY MESSAGES

- 1. A gradual warming trend persists much of this week.

- 2. A wetter pattern develops into the weekend with some tropical connections.

DISCUSSION

Key Message 1: A gradual warming trend persists much of this week.

Rain-free conditions persist for the next several days with surface high pressure over the region and PWATs sitting at less than 0.75 inches through at least Thursday. Persistent northeasterly low level flow into the mid-week should keep temperatures pleasant, though a slight warming trend will occur as temperatures return to the low-mid 80s by Thursday and Friday.

Key Message 2: A wetter pattern develops into the weekend with some tropical connections.

Attention turns to a more active weekend as moisture returns across the region with southerly to southeasterly flow aloft. Although guidance has struggled with the timing of what is now Tropical Depression 9 (TD9) currently in the Bay of Campeche, confidence is increasing that moisture from this system may impact the region over the upcoming weekend. Guidance is in decent agreement in the overall track with fairly predictable steering flows across the Gulf into the southern US, bringing the system somewhere from Louisiana to the panhandle of Florida; timing and intensity differences within the guidance are high, especially between AI, hurricane, and global physics based ensembles however. Regardless, a strong surface ridge with persistent, deep easterly component will effectively serve as a road block to how far east the core of the tropical system can make it. Despite the core of the system likely remaining well to our west, this surface ridging presents an impressive overrunning setup with a plume of deep tropical moisture surging northward along the system's eastern flank. Model cross sections show the expected impressive fetch of potential isentropic lift throughout the area along with nearly saturated and weakly unstable profiles as the tropical moisture arrives as effectively a warm front. Exactly where strongest meso- synoptic scale lift sets up and the extent of the high PWAT's are still very difficult to guess at, but chances for impactful heavy rain are there. WPC has introduced a Day 5 (Saturday) Slight Risk ERO for much of the FA. Regardless, widespread rain with some breezy winds as the pressure gradient tightens across the area looks to be the most likely impact at this time, but obviously lots to still watch and monitor in the coming days. Finer scale details will determine if this would just be a beneficial rain or more of a flooding threat.

CAE WATCHES/WARNINGS/ADVISORIES

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