Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
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605 FXUS62 KCAE 220531 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 131 AM EDT Sat Jun 22 2024 .SYNOPSIS... Moisture will increase across the area over the weekend as low pressure approaches from offshore. Above normal temperatures are expected by Sunday into early next week. Heat Advisories may be possible from Monday through Wednesday. Expect scattered diurnally driven showers and thunderstorms for much of the short and long term forecast. && .NEAR TERM /UNTIL 7 AM THIS MORNING/... KEY MESSAGES: - Tropical wave/low pressure will result in increased humidities. The center of the tropical low and associated wave will move onshore near the Florida/Georgia Atlantic border shortly after sunset. Low level moisture has been surging in from the southeast on the north side of the wave, and will continue to do so overnight. Dew points have already risen into the 70s in the southeasternmost counties, and that should make it to the I-20 corridor by midnight and over the entire FA by morning. The increase in moisture should help promote some patchy ground fog in the eastern half of the area toward sunrise. && .SHORT TERM /7 AM THIS MORNING THROUGH 6 PM SUNDAY/... KEY MESSAGES: - Increasing moisture will lead to a chance for afternoon and evening thunderstorms. Surface low pressure will move south of the forecast area on Saturday with deep easterly flow leading to increasing moisture. PWAT values rise to 1.75 to 2.00 inches, near to slightly above normal, with highest values to the south. Expect showers and thunderstorms to develop in the afternoon as the air mass becomes conditionally unstable through daytime heating. We would expect coverage to be highest across the southern Midlands and CSRA where moisture is deeper and due to stronger subsidence to our north. Low lapse rates point to limited updraft strength and a low threat of severe weather. Convection should diminish in the evening with loss of daytime heating, however as moisture advection increases through the night we may see an isolated shower pop up during the early morning Sunday. Temperatures will be around normal in the low to mid 90s. Lows overnight will be mild in the low to mid 70s. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... KEY MESSAGES: - Temperatures rise late this weekend into mid-week. - Heat Advisory criteria possible Monday through Wednesday. Daytime temperatures from Monday through Wednesday may be near 100 degrees. Varying levels of moisture during this period limit confidence in reaching Heat Index values above 105. Daily showers and thunderstorms could also hinder heating. Late this weekend, 850mb temps warm leading to daytime highs rising into the mid 90s for most areas. This warming trend continues into Monday with highs into the upper 90s to near 100 degrees ahead of a weak cold front which will bring drier air into the region. Much of the area will be in northwest flow aloft with rather strong downslope flow on Monday. The downslope flow would contribute to the hot temps but would also dry out of the low levels. There may be a period on Monday where lingering low level moisture combined with warm temps raise Heat Index values into the 100 to 105 range. However confidence in reaching Heat Advisory criteria is somewhat limited by the potential for afternoon showers and thunderstorms. With drier air over the area for Tuesday, rain chances and dewpoints will be lower. Highs will still be in the upper 90s to near 100 but with drier air in place Heat Adv criteria looks less likely. Global ensemble means favor upper troughing in the Tennessee Valley moving into the Southeast mid-week, pushing another weak cold front toward the area. Moisture appears to increase again with over 75 percent of ensemble member PWAT values over 1.5 inches by Thursday. Increasing moisture and continued warm temperatures may push Heat Index values to near Advisory criteria on Wednesday. A cold front pushing into the Southeast late in the week and increasing cloud/precip chances should promote slightly cooler weather towards the end of the long term. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... Low clouds beginning to move over the terminals early this morning. Restrictions have moved over OGB and should move over the Columbia terminals over the next hour or so. Highest confidence in IFR ceilings at OGB so have left prevailing IFR ceilings in there but have put IFR ceilings in a TEMPO group for Columbia terminals with guidance trending more optimistic in restrictions this morning. Restrictions should dissipate shortly after sunrise with a cumulus field developing around 4kft. Chances for showers and thunderstorms mainly for OGB and possibly the Augusta terminals but confidence is a bit limited to include in this TAF update. Winds will generally be out of the ESE this morning, although will likely become mostly light and variable in the pre-dawn hours. Winds increase again late this morning, shifting out of the SSE between 5 to 10 knots. EXTENDED AVIATION OUTLOOK...Increasing chances for afternoon scattered showers and thunderstorms and associated restrictions Sunday through Wednesday. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$