textproduct: Columbia

WHAT HAS CHANGED

Fire Danger Statement this afternoon into tonight and aviation discussion for 18z.

KEY MESSAGES

- 1. Well above average temps this afternoon ahead of a front bringing the potential for a few thunderstorms.

- 2. Elevated fire weather concerns for today and Tuesday.

DISCUSSION

KEY MESSAGE 1: Well above average temps this afternoon ahead of a front bringing the potential for a few thunderstorms.

Broad ridging aloft to our southwest is helping to push temps into the mid to upper 80's this afternoon ahead of an approaching front, which is currently moving through the Upstate and Piedmont regions as I write this. Breezy southwest winds gusting to around 20 mph are also expected to continue ahead of the front. Due to deep mixing and 850mb temps around 15 C, temps continue to be 15-20F above average for this time of year. Locations south and east of I-20 will likely approach the 90F mark. Temperatures in the northern and western portions of the forecast area might have already peaked for the day.

This cold front moves through the area later this afternoon and bring a slight chance of some showers-thunderstorms, mainly near the I-95 corridor and areas east of there. Overall, the setup for any severe or even strong thunderstorms continues to wane for this front as forcing, instability, and moisture availability were very unlikely to all line up. A few showers and thunderstorms are still expected across the coastal plain and into the southeastern Midlands, but coverage will be hampered by significant dry air and a relative lack of instability as a result. HREF members still generally produce a few showers and thunderstorms near I-95 during peak heating as the surface front moves through, but robust convection is not likely and therefore the severe potential is low.

The frontal boundary is forecast to linger south of the forecast area for the next couple of days, so a rogue shower or storm is possible tomorrow as well as Wednesday, with slightly higher chances on Wednesday.

KEY MESSAGE 2: Elevated fire weather concerns for today and Tuesday.

Current RH values are generally ranging from 35-45% this afternoon ahead of the incoming front. After the front passes, drier air and breezy conditions are expected to filter into the area. Near critical to critical RH levels are anticipated after the front passes later this afternoon and evening. RH levels are expected to be near critical to critical again tomorrow afternoon as tomorrow will likely be the drier day in terms of RH's. Winds are also expected to gust to 20-25 mph this afternoon into the overnight hours, and close to that tomorrow. So given relatively dry fuels, there is an increasing fire danger potential starting this afternoon through tomorrow. There is a Fire Danger Statement in effect for late this afternoon into tonight for Newberry, Fairfield, Lancaster, Kershaw, and Chesterfield Counties. We may need to issue one for tomorrow as well, but will hold off until at least today's statement expires.

AVIATION /18Z MONDAY THROUGH SATURDAY/

VFR but breezy conditions expected through the 24hr forecast period.

Wind, wind, and more wind. That will be the primary issue with the aviation over the next 24 hours. A cold front will be passing through the forecast area through this afternoon, moving into the coastal plain late in the afternoon and into the evening. Winds ahead of the front are turning more out of the west/northwest, and will turn more northwest to north-northwest as the front pushes east. Guidance continues to show sustained wind this afternoon, tonight, and into Tuesday morning between 10-15 knots. There will be some higher gusts over 20 expected due to some momentum transfer of stronger winds aloft tonight down the surface. Wind direction will eventually shift more northeasterly towards 06z onward. Winds may diminish some by late Tuesday morning, dropping to less than 10 knots towards 15z as the low-level jet weakens.

As for restrictions, the airmass remains on the drier side with the front, and rainfall would be very limited this afternoon. Have not included mention in tafs due to low probability at this time. The drier airmass and winds tonight will inhibit fog, and keep skies only partly cloudy with higher cirrus passing through.

EXTENDED AVIATION OUTLOOK...Breezy winds continue into Tuesday behind the cold front. VFR conditions are expected for much of the upcoming week.

CAE WATCHES/WARNINGS/ADVISORIES

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