textproduct: Columbia

WHAT HAS CHANGED

Increased Fire Danger today. Nearing Cold Weather Advisory criteria Friday morning, and again Monday morning. The potential for a weekend coastal system continues which may bring winter weather to portions of the area, although uncertainty remains high.

KEY MESSAGES

1) Dry and breezy today and Friday with an enhanced fire danger risk.

2) Temperatures near cold weather advisory Friday morning, and again Monday morning.

3) Potential for winter weather Sunday as a coastal low develops. Significant uncertainty remains.

DISCUSSION

Key Message 1: Dry and breezy today and Friday with an enhanced fire danger risk.

Strong cold advection behind the exiting cold front will bring an increase in winds across the region today. Wind gusts over 20 mph, with a few possibly reaching 30 mph, will be possible from late morning and through much of the afternoon hours. With drier air and lower dewpoints moving in along with the winds, minimum RH values this afternoon are forecast to drop to between 20-25 percent over a large portion of the forecast area. The light rain that fell yesterday will help out early in the day, but overall fuels remain dry, and the combination of winds and low RH values will aid in creating additional dry conditions. This sets up for an enhanced fire danger today, and we are issuing a Fire Danger Statement to highlight this from 10 am to 7 pm today. Friday will bring another round of dry weather, but winds will be slightly weaker through the day, so the threat should be reduced a little then, but still can not rule out the need for another FDS then either.

Key Message 2: Temperatures near cold weather advisory Friday morning, and again Monday morning.

Friday morning is shaping up to be rather cold across the area as surface high pressure settles into the region. Winds should mostly decouple late tonight, and do expect a close to ideal radiational cooling night to occur. High probability of most areas reaching at least 20 degrees tonight, but blends have generally less than a 30 percent chance of dropping to or less than 15 degrees for our apparent temperatures by morning. Do think we'll get close to Cold Weather Advisory criteria in a few isolated spots, but not for a long enough period for the majority of the forecast area tonight. Basically still a borderline situation at this time. Bigger concern for the need for a Cold Weather Advisory product may arrive for Monday morning. Guidance showing a slightly higher probability of seeing apparent temperatures at that time below 15 degrees for a much larger portion of the forecast area. Will continue to monitor the trends as we go through the weekend.

Key Message 3: Potential for winter weather Sunday as a coastal low develops. Significant uncertainty remains.

Winter weather potential continues to be highlighted for Sunday but significant uncertainty remains in the specifics. We can be relatively confident in the overall synoptic pattern early in the weekend with broad troughing over the eastern CONUS. Models continue to show high confidence in a highly amplified digging trough into the Mississippi Valley Saturday into Saturday night with the NAEFS mean indicating that 500mb heights will be below the first percentile. The progression of this trough and when it stops digging south and moves towards our area will be pivotal in the winter weather potential. Blended guidance favors temperatures in the upper 50s and low 60s Saturday with a much colder air mass moving into the Southern Plains. As this air mass moves towards the area, cold advection will strengthen into Saturday night. Forecast soundings favor wet bulb temperatures near freezing through a layer extending to about 5000 feet. This creates significant uncertainty as a coastal low develops Sunday and increased moisture in southwest flow leads to developing, potentially mixed, precipitation. NBM probabilities of measurable snow (0.1" or greater) are between 40 to 50 percent throughout the area, a slight increase from the afternoon forecast package. The Probabilistic Winter Storm Severity Index indicates around a 20-30% chance of minor impacts in the forecast area.

AVIATION /06Z THURSDAY THROUGH MONDAY/

VFR conditions are generally expected throughout the period.

Cold front is currently just of to the west of the forecast area and will be quickly pushing eastward and through between 07z-12z. Winds will turn from southwesterly to more northwesterly with its passage, and do expect to see an increase in wind gusts for a period through sunrise behind the front, especially across the CSRA sites of ags/dnl. Wind gusts will increase through the daytime hours, with the potential for gusts of 20-25 knots from late morning and through the afternoon as strong cold advection takes hold. Winds will diminish towards sunset as low-levels begin to decouple Thursday evening. As for clouds/visibilities, with the very dry airmass pushing in behind the front, vfr conditions should prevail through the period. Early on though, upper level cirrus streak will start off the period at all sites, along with a few mid-level cu along the front pushing through. during the day, skies will become mostly clear as even drier air moves into the area.

EXTENDED AVIATION OUTLOOK...VFR conditions are expected Thursday night and Friday. Another system expected to impact the region over the weekend and some restrictions are possible.

CAE WATCHES/WARNINGS/ADVISORIES

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