textproduct: Columbia

WHAT HAS CHANGED

Confidence increasing in potential for frost/freeze this weekend. Aviation discussion updated for the 06z TAF issuance.

KEY MESSAGES

- 1. Seasonable conditions this week with a front ushering in a colder air mass for the end of the week and into the weekend.

DISCUSSION

Key Message 1: Seasonable conditions this week with a front ushering in a colder air mass for the end of the week and into the weekend.

A relatively quiet weather pattern continues through midweek as high pressure remains in control. Temperatures will gradually warm each day, with highs reaching the mid-70s. Efficient radiational cooling will result in large diurnal temperature swings, though overnight lows will gradually warm as well into Thursday morning as the front approaches and winds increase out of the southwest with increasing cloud cover.

Ensemble means continue to depict a strong trough digging into the central and eastern CONUS, bringing the potential for the coldest temperatures of the season so far to the region. Ahead of the approaching front on Thursday, breezy southwest winds may approach Lake Wind Advisory criteria, with scattered showers also possible. However, moisture remains somewhat limited with ensemble mean PWATs around 1 inch. As a result, rainfall amounts are expected to remain relatively light, especially given the progressive nature of the front. A significant air mass change is expected behind the front, as strong cold air advection and persistent northwest flow bring much cooler temperatures this weekend. GEFS and ECMWF ensemble means indicate 850-mb temperatures around 10C below normal by the weekend. Blended guidance suggests greater than 50% probabilities of minimum temperatures falling below 35F Saturday through Monday mornings. Frost and freeze products may be needed this weekend as a result.

AVIATION /06Z TUESDAY THROUGH SATURDAY/

Generally VFR conditions expected through the period.

High pressure continues to build over the area through tonight bringing dry and fair weather with only some passing high clouds. Surface winds should generally be calm overnight. Despite drier air and lower dewpoints compared to last night, cannot completely rule out some brief river valley fog once again, particularly at prone locations AGS/OGB. A TEMPO IFR group has been added at AGS to account for this between 10-13Z. A chance for LIFR at AGS cannot be ruled out. Less confident for fog development at OGB. Winds will be slow to increase on Tuesday, but should become SLY/SWLY at 5 knots or less after 15z. Calm winds again Tuesday night with generally VFR conditions and increasing cloud cover.

EXTENDED AVIATION OUTLOOK...Dry air will likely prevent widespread restrictions through the extended with moisture increasing ahead of an approaching frontal boundary on Thursday.

CAE WATCHES/WARNINGS/ADVISORIES

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