textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated for 00z TAF issuance.

KEY MESSAGES

- 1. Frost Advisory tonight as light winds, clear skies and cold temperatures will lead to areas of frost developing.

- 2. Warming into the weekend with a cold front moving in early next week.

DISCUSSION

KEY MESSAGE 1: Frost Advisory tonight as light winds, clear skies and cold temperatures will lead to areas of frost developing.

High pressure ridging over the forecast area with winds becoming light. HREF guidance indicates increasing mid-level clouds this evening into early tonight which will somewhat limit radiational cooling early. After midnight, consensus guidance clears skies out which will lead to a relatively favorable environment for frost to develop, especially near sunrise, although low level moisture will likely be marginal. With blended guidance showing relatively low probabilities of sub-freezing temperatures and a moderating air mass tonight into Thursday morning, have opted to issue a Frost Advisory 1am to 9am Thursday morning with temperatures generally between 33- 36F, although some typical cold spots may dip below freezing.

KEY MESSAGE 2: Warming into the weekend with a cold front moving in early next week.

Warming trend expected for the second half of the week as upper ridging strengthens, centered to the west of the area with blended guidance showing relatively high confidence temperature forecast through the weekend with an IQR of only a few degrees. By Sunday, NAEFS mean indicates that 850mb temperatures will be above the 90th percentile in what is expected to be the warmest day of the period, generally mid 80s. Moisture gradually increasing as well into this weekend with between 50-70% of GEFS and EC ensemble members indicating PWATs rise above an inch Saturday into Sunday. While overall, blended pops remain low, mainly owing to limited forcing with ridging over the area, there remains an outside shot at some light rain showers or even an isolated storm this weekend. Higher chances for precipitation will be associated with a front that is expected to move into the area early next week. There remains significant uncertainty with the progression of the front leading to lower confidence in temperature and precipitation forecast early next week.

AVIATION /00Z THURSDAY THROUGH MONDAY/

VFR Continue at the Terminals Tonight....

A large swath of mid to high level cloudiness is currently moving through the region. These ceilings should remain well above MVFR heights and confidence in VFR conditions during the next twenty-four hours remains high. The lowest levels of the atmosphere remain rather dry and fog is not expected to impact visibilities tonight, despite some moisture recovery. Winds should be light or calm tonight and light and variable on Thursday.

EXTENDED AVIATION OUTLOOK...Chances for restrictions remain low through at least Friday. Rain chances, and possible restrictions, increase this weekend and into next week.

CAE WATCHES/WARNINGS/ADVISORIES

SC...Frost Advisory from 1 AM to 9 AM EDT Thursday for SCZ016-018- 020>022-025>031-035-037-038-041-115-116-135>137. GA...Frost Advisory from 1 AM to 9 AM EDT Thursday for GAZ040- 063>065-077.