textproduct: Columbia

WHAT HAS CHANGED

Updates to Key Messages. Aviation discussion updated for 18z TAFs.

KEY MESSAGES

- 1. Cooler temps into mid-week. Warming and wetter pattern develops into the weekend with some tropical connections.

DISCUSSION

Key Message 1: Cooler temps into mid-week. Warming and wetter pattern develops into the weekend with some tropical connections.

Pleasant autumn weather with a drier surface high pressure over the Mid-Atlantic will build into the region today, with PWATs dropping to around 0.50 inches. Persistent northeasterly low level flow into the mid- week should keep temperatures near to just below normal with dry weather expected. Weak surface ridging is expected to continue into the late week along with some building heights and temps returning to near-above average.

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 92L, currently in the Bay of Campeche and showing some loose signs of organization as of 18z, probs are up to 90% of development in the next 7 days per the NHC, confidence is increasing in a tropical connection to this flow. 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. But 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 once the system actually forms. Finer scale details will determine if this would just be a beneficial rain or more of a flooding threat.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

VFR conditions through the TAF period.

Drier air continues to push into the area, allowing this morning's low ceilings to clear. A few high clouds are passing to our south and east, otherwise mostly sunny skies prevail. East- northeast winds have increased to around 10 knots, with occasional gusts of 15-17 knots. Winds should diminish around sunset, with mostly clear skies expected tonight. Fog and low stratus are not expected, though a few localized areas may develop along the rivers. Otherwise, VFR conditions continue into Wednesday with light northeast winds and only a few passing cirrus clouds.

EXTENDED AVIATION OUTLOOK...VFR conditions are expected into the late week with drier air in place. Restrictions may become possible by the weekend.

CAE WATCHES/WARNINGS/ADVISORIES

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