Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
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042 FXUS62 KCAE 301031 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 631 AM EDT Sun Jun 30 2024 .SYNOPSIS... Hot and humid conditions continue, with afternoon and evening showers and thunderstorms again today ahead of an approaching frontal boundary. The front is expected to bring slightly cooler and drier conditions to start off the work week, but building high pressure will allow the return of temperatures near the century mark by mid to late week. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Heat Advisory in effect during the afternoon and early evening. - Scattered to numerous showers and thunderstorms possible this afternoon/evening ahead of a cold front. Upper ridge that has been across the area will begin to shift off to the west as an approaching upper trough digs towards the Mid-Atlantic this afternoon and evening. At the surface, a cold front will push southward towards the forecast area through the day before moving into and eventually into the southern cwa overnight tonight. In addition, a lee-side trough should set up ahead of the surface front this afternoon, helping produce additional convergence for shower and storm development. Pwat readings at or above 2 inches will continue today. With afternoon high temperatures expected to climb into the middle 90s, and when combined with the moisture, heat index values in the 105-111 are forecast. Current heat advisory will remain in effect for this afternoon across the entire cwa. With that being said, one fly in the ointment that could keep conditions slightly cooler would be the development of the showers and thunderstorms this afternoon, which would produce additional cloud cover along with rainfall. Models do show development beginning generally between 18z-21z, with activity then moving across the area into the evening hours. Instability will be rather moderate during peak heating. Best shear remains north of the area along the Mid-Atlantic corridor. This would help limit severe potential this afternoon, and SPC keeps the cwa in a Marginal Risk through the period. Can not rule out some strong gusts, along with periods of heavy rainfall, in some of the stronger storms. Activity should be diminishing somewhat again overnight, with highest rainfall potential moving closer to the coastal plain through the night as the front moves through. Overnight lows will still be muggy as the drier air lags behind the front somewhat. Lows tonight in the middle 70s. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... Key messages: - A brief respite from the heat and humidity. A frontal boundary stalls across or just south of the eastern Midlands and lower CSRA during this time period. Noticeably cooler and somewhat drier air filters into the Northern and Central Midlands with precipitable water levels decreasing below 1.5 inches north of I-20 and below one inch close to the North Carolina state line. Scattered to numerous afternoon and evening thunderstorms will be possible south of I-20 while the Northern Midlands might see at best a slight chance of diurnal convection. Temperatures will be below normal for early July with highs in the mid to upper 80s and lows in the mid to upper 60s. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Key Messages: - Heat and humidity return as high pressure aloft rebuilds. The model ensembles depict much above normal H5 heights building back over the Southeast U.S. during the second half of this week. This should lead to much above normal temperatures. The probabilistic guidance shows a better than 35 percent chance of high temperatures in excess of 100F both Friday and Saturday. Precipitable water levels increase to greater than 1.75 inches. Isolated to scattered diurnal convection should develop primarily near the remnants of a frontal boundary on Wednesday and then primarily near the sea breeze front Independence Day through Saturday. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... VFR Conditions Expected through the period outside of any convection. Partly to mostly cloudy vfr cloud cover through the period. A cold front will be approaching the region from the north through the day before pushing through tonight. Scattered to numerous showers and thunderstorm should form between 18-21z, impacting all taf locations at some point into the evening. Have continue with mention of vcts beginning at 19z at all locations, lasting into the evening. Although much of the period will be vfr, do expect that mvfr conditions could develop in convection. After 03z tonight as the front moves in and convection pushes east, rainfall should end at all taf sites, with vfr early into the night. Model guidance is now trending towards showing some ifr stratus near the tail end of the taf period, but confidence is low at this time due to uncertainty in overall rainfall and position of the front. EXTENDED AVIATION OUTLOOK...Low chances for showers and thunderstorms during the afternoon and evening hours continue Monday and Tuesday, mainly over the eastern/southern Midlands and southern CSRA. Stratus and fog possible each morning. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...Heat Advisory from noon today to 7 PM EDT this evening for SCZ016-018-020>022-025>031-035-037-038-041-115-116- 135>137. GA...Heat Advisory from noon today to 7 PM EDT this evening for GAZ040-063>065-077. && $$