textproduct: Columbia

WHAT HAS CHANGED

Decreasing rain chances rest of this evening. Better mixing behind the front tomorrow may allow dew points to mix out slightly better. Confidence has increased slightly in increased fire danger threat this week. Aviation discussion updated for 00z forecast.

KEY MESSAGES

- 1. Showers will diminish the remainder of this evening into tonight.

- 2. Increased fire weather concerns by mid week with a very dry air mass and gusty winds.

DISCUSSION

KEY MESSAGE 1: Showers will diminish the remainder of this evening into tonight.

Per the 23z surface analysis, the surface cold front is now working into the northern Midlands with dew points behind it quickly falling into the 40s toward the Upstate and eventually the 30s further northwest into the Tennessee Valley. The last batch of showers is pushing through the eastern Midlands and southern CSRA, before this front will clear the area, ushering in much drier air and bringing an end to rain chance tonight. There is little signal for rain chances much of next week as well with robust surface high pressure working into the area and upper ridging generally in place.

KEY MESSAGE 2: Increased fire weather concerns by mid week with a very dry air mass and gusty winds.

A much drier and cooler air mass is expected to build into the region this week behind the cold frontal passage tonight. Overall, a look at 72hr MRMS QPE across the FA shows that 0.10-0.25" of rain was seen with localized spots over 0.50" where convection managed to reach over the last couple days. These amounts likely will not significantly help our drought conditions and thus confidence in fire weather concerns this week have increased slightly. The main change to the outlook before the mid week is the latest HREF and run of the experimental NBM 5.0 have surface dew points mixing out slightly better tomorrow afternoon, which is further supported by BUFKIT soundings as decent mixing occurs with lingering CAA in the region. Both the 12z HREF and latest NBM 5.0 have probabilities for dew points less than 32F tomorrow afternoon between 50-70% for much of the CWA. With these lower dew points, RH values during the afternoon could near critical values, but northerly winds are expected to remain very light.

A strong surface high pressure system is forecast to build across the Ohio Valley into the Mid-Atlantic midweek. This 1036mb high would be nearly climatological max according to the NAEFS supporting dewpoints falling into the 20s and 30s resulting in RH values at critical values between 20-30 percent. This paired with breezy northeasterly winds gusting between 20-30 mph into the mid week given the current drought conditions will create increased fire danger conditions.

AVIATION /00Z MONDAY THROUGH FRIDAY/

VFR through the period

Last meaningful line of showers has cleared the Augusta and Columbia TAF sites, and will push through OGB in the next hour. There is a lone shower along the real front in upstate South Carolina around sunset, but this should dissipate before impacting any of the TAF sites. There is a chance for some cigs this evening before the cold front moves through late, but the will be high enough to avoid any restrictions.

Winds are the trickiest part of this forecast cycle. They should remain mainly south of west until the front passes late this evening, then veer to northwest for a few hours before turning north after midnight, and eventually east of due north by morning. I don't expect the winds to exceed 10 knots overnight, although there could be some brief gustiness along and behind the front for a few hours in the middle of the night. Winds will diminish during Monday afternoon as the surface pressure gradient quickly relaxes.

EXTENDED AVIATION OUTLOOK...The chance of restrictions is low through at least mid-week.

CAE WATCHES/WARNINGS/ADVISORIES

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