textproduct: Columbia

WHAT HAS CHANGED

Chance for anything more than flurries Thursday morning continue to diminish. The weekend is looking more active with a potential coastal system.

KEY MESSAGES

1) Rain chances continue today with a very slight chance of flurries late tonight.

2) Dry and breezy Thursday and Friday with an enhanced fire danger risk.

3) Very cold weather continues into the weekend. Temperatures near cold weather advisory Friday morning.

4) Potential for a coastal low on Sunday is loaded with uncertainty.

DISCUSSION

Key Message 1: Rain chances continue today with a very slight chance of flurries late tonight.

The prefrontal trough will continue to produce some light rain showers across the region this afternoon. The initial batch of rain this morning helped moisten the surface layer up a bit, so any showers the rest of the day should more effectively get to the ground. The heaviest batch of rain is setting up along the I-95 this afternoon, where rain totals 0.1-0.25" is possible through 6pm. Otherwise totals will be low. Lingering shower activity moves out this evening, with only a few wrap around showers possible early Thursday as the steepening lapse rates, frontogenetic forcing, and mid-level trough axis approach. Surface layer temps will cold enough at that point for some flurries, but overall the dry air will win out and shouldn't be anything more than a few flakes.

Key Message 2: Dry and breezy Thursday and Friday with an enhanced fire danger risk.

Cold advection regime Thursday afternoon will bring near Red Flag conditions with wind gusts around 25-30 mph along with relative humidities between 20-25%. Some light rain across the region should help mitigate some of the fire concern, but overall fuels are still dry and meteorological it is a good setup for enhanced fire danger.

Key Message 3: Very cold weather continues into the weekend. Temperatures near cold weather advisory Friday morning.

After 24-36 hours of strong cold advection behind the aforementioned front, near cold weather criteria low temps are expected early Friday. With high pressure settling nearby, decent radiational cooling should enhance the advected cold airmass and drop temps down into the upper 10's in most spots early Friday; NBM members continue to show a 60-80% chance of sub-20 F temps in the morning, with wind chills a bit lower. It still looks borderline if we will need a cold weather advisory product for Friday across the southern and eastern portions of the forecast area.

Key Message 4: Potential for a coastal low on Sunday is loaded with uncertainty.

A digging trough in the central US and then into the northern Gulf of America will bring the potential for a coastal low as we move into Sunday. Guidance remains, expectedly, all over the place with little run to run or internal ensemble consistency. So all that needs to be said right now is this: lots of uncertainty remains but this is a fairly good pattern for an overrunning wintry precip event in eastern GA and SC, with a developing low in the GoA, and sufficient cold air & moisture in place. Generally southern snow storms start to come into decent focus in the models around 72 hours.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

Predominantly VFR conditions expected through the forecast period, with some brief MVFR conditions this afternoon or evening ahead of a front.

Southwesterly flow ahead of the approaching front will bring a bit more moisture to the area. Mainly mid and high levels cloud cover will continue to increase this afternoon with some CIGS lowering toward upper-end MVFR heights in areas of -RA. Very dry surface conditions will largely limit VSBY reductions, though some brief MVFR VSBYs are possible at OGB. Additionally, guidance is backing off on MVFR CIG restrictions later this evening except for at AGS/DNL. Overall, the front should move through late tonight or very early on Thursday morning, with skies clearing from west to east and ending up close to SKC by daybreak Thursday morning.

Surface winds should continue from the SW this afternoon around 10 kts with a few higher gusts. A shift toward the west and eventually northwest will occur beginning around 05z-06z as the front moves through. Additional breeziness is anticipated behind the front with gusts to near 20 kts continuing through the day on Thursday.

EXTENDED AVIATION OUTLOOK...Strong gusty winds expected on Thursday but otherwise VFR conditions expected. Another system expected to impact the region over the weekend and some restrictions possible.

CAE WATCHES/WARNINGS/ADVISORIES

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