textproduct: Columbia

WHAT HAS CHANGED

A Freeze Watch is in effect for the whole CWA late Saturday night into Sunday morning. Aviation Discussion updated.

KEY MESSAGES

- 1. Patchy frost possible tonight and a Freeze Watch is now in effect late Saturday night into Sunday morning. Below normal temperatures likely persist into early next week.

DISCUSSION

Key Message 1: Patchy frost possible tonight and a Freeze Watch is now in effect late Saturday night into Sunday morning. Below normal temperatures likely persist into early next week.

The secondary cold front is pushing off to the east of the forecast area this morning. Much drier air is now pushing in behind this front, with dewpoints already falling into the 30s across much of the region.

Afternoon high temperatures should top out in the upper 50s to low 60s and downsloping northwesterly flow will aid in dropping dewpoints into the low 30s. Persistent CAA will aid in bringing the first night of cold temperatures tonight into Saturday morning with lows in the mid to upper 30s expected. While patchy frost in sheltered spots is certainly possible, have decided to hold off on a Frost Advisory tonight for the moment. This comes as BUFKIT soundings and high-res models indicate winds overnight should remain elevated (around 3-5 kts) with a fairly tight pressure gradient remaining in place. The chilliest conditions are expected Saturday night into Sunday morning, where temperatures near to below freezing are increasingly likely (NBM probabilities for temperatures less than 32F are greater than 50%, especially north of I-20). A few northern spots dipping into the upper 20s is not out of the realm of possibilities with strong radiational cooling conditions expected. Due to increasing confidence in a freeze, a Freeze Watch is now in effect for the whole CWA late Saturday night into Sunday morning. Upcoming forecast packages will evaluate upgrading this to a Freeze Warning. Well below normal temperatures are likely to persist Sunday and into the early week as high pressure remains anchored just north of the region.

The forecast into the mid week becomes a but murkier, but global models are trending toward mid level ridging building in with temperatures possibly trending a bit closer to normal.

AVIATION /13Z FRIDAY THROUGH TUESDAY/

VFR conditions expected through the period.

NW flow through the period will drive cool, dry air into the forecast area. Westerly winds around 5 knots this morning are expected to increase once again after 15Z with gusts between 15 and 20 knots possible through the afternoon. As the base of the trough swings into the Southeast we will see some shallow mid- level clouds develop from mid-day into the evening but ceilings will remain VFR. Fog not expected with a dry air mass over the region.

EXTENDED AVIATION OUTLOOK...Dry air will likely prevent widespread restrictions through the extended.

CAE WATCHES/WARNINGS/ADVISORIES

SC...Freeze Watch from late Saturday night through Sunday morning for SCZ016-018-020>022-025>031-035-037-038-041-115-116- 135>137. GA...Freeze Watch from late Saturday night through Sunday morning for GAZ040-063>065-077.