textproduct: Columbia

WHAT HAS CHANGED

Key message #1 tweaked a little bit to discuss potential earlier arrival of clouds tonight. Updated Aviation discussion for 00z TAF issuance.

KEY MESSAGES

- 1. Freezing temperatures expected tonight & may harm sensitive vegetation.

DISCUSSION

KEY MESSAGE 1: Freezing temperatures expected tonight & may harm sensitive vegetation.

High pressure will slide just to our north tonight and set us up for a cold night ahead. A combination of some mid-level cloud cover moving in late tonight and boundary layer winds will help offset low level dry air, so far from a truly ideal radiational cooling setup but the airmass in general is cold-dry; temps this evening are in the upper 40's with dew points below 20 F. Regardless, with the initial clear skies and generally light winds after sunset, some sub-freezing temps for several hours remain likely by Wednesday morning. NBM mean is around 30 F for much of the area, which does a fairly reasonable job depicting the early morning cloud cover. However, the latest guidance, including the NBM and HRRR have the cloud cover arriving an hour or two sooner than previous model runs, which could limit the overall cooling tonight. Nonetheless, keeping the forecast lows the same for now as temps should still drop quickly after sunset under the clear skies. These temps should taper off as clouds move in, but how cold it gets will depend somewhat on the arrival of these clouds.

Otherwise widespread hazardous weather is unlikely through the remainder of the period.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

VFR conditions expected through the TAF period.

West to northwest winds continue to diminish this evening and are expected to become light and variable overnight. After about 13z, winds shift to more northeasterly and remain on the lighter side, generally 5-8 kts. The current clear skies at the terminals are expected to give way to some scattered high clouds during the overnight hours.

EXTENDED AVIATION OUTLOOK... No significant aviation concerns through the week with drier air moving into the region.

CAE WATCHES/WARNINGS/ADVISORIES

SC...Freeze Warning from 2 AM to 10 AM EDT Wednesday for SCZ016-018- 020>022-025>031-035-037-038-041-115-116-135>137. GA...Freeze Warning from 2 AM to 10 AM EDT Wednesday for GAZ040- 063>065-077.