textproduct: Columbia

WHAT HAS CHANGED

Significant rainfall remains unlikely through early next week. Aviation updated for 06z issuance.

KEY MESSAGES

- 1. Outside of a few showers late this weekend rain chances remain low through mid-next week before the pattern becomes active late next week.

DISCUSSION

Key Message 1: Outside of a few showers late this weekend rain chances remain low through mid-next week before the pattern becomes active late next week.

Another reinforcing surface high pressure is settling into the Mid-Atlantic this evening, with drier and cooler air ushering into the area for the weekend. As this occurs, high level clouds are approaching from the west, a harbinger of a shortwave trough that is expected to slowly stretch out over the next couple of days. A modest increase in moisture is expected as the aformentioned trough pushes eastward towards the area through the weekend but few impacts are expected out of that. Guidance shows some scattered showers possible on Sunday evening and into early Monday, but otherwise, mid-level clouds and cooler temperatures are expected this weekend.

As we get into next week, a slow increase in afternoon temps is expected through the week, and confidence is relatively high that we should see above normal temps for much of the week. This owes itself to persistent deep troughing to our west and the expectation that broad and persistent southwesterly flow will overspread the southeastern CONUS for much of the week. However, parsing much more is difficult to impossible. The pattern is forecast to become increasingly complex next week, with a very meridional pattern setting up to our west. Guidance is handling this poorly across the board, with physics based and AI guidance consistently showing large run-to-run differences in the 500 hPa heights even at hours as near as 96-120. This is unusual and indicative of a pattern that has inherent unpredictability involved. As such, we will parse what we can (above normal temps, an increased likelihood in rain chances by the end of next week) and avoid speculating beyond that.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

LLWS possible early this morning, otherwise VFR conditions are expected through the TAF period.

Satellite loops showing thin broken cirrus moving across the region, and this should remain the primary cloud cover throughout the period. Primary issue this morning will be the potential for llws to develop. Surface winds currently are near calm. Those should increase slightly towards 09z to around 5 knots as winds aloft also show an increase as a low-level jet develops and strengthens. Model time sections indicating that by 09z, winds around 1 kft will be near 35 knots, remaining that way until after sunrise when the inversion breaks and winds can mix towards the surface. Although it may be borderline for llws overnight, have elected to put mention of it in all taf sites beginning at 09z lasting through 14z. After 14z, the inversion lifts and winds will become mixed. This will also increase surface winds to above 10 knots, and introduce wind gusts from mid morning through the afternoon of between 15-20 knots. By sunset the inversion will being to set up again, eliminating surface gusts, but the sustained winds will only drop to around 5 knots. No visibility restrictions expected due to the good low-level winds.

EXTENDED AVIATION OUTLOOK...Low level moisture increases early next week and may lead to ceiling restrictions. Rainfall chances increase mid-week.

CAE WATCHES/WARNINGS/ADVISORIES

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