Area Forecast Discussion
Issued by NWS Columbia, SC

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726 FXUS62 KCAE 120618 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 218 AM EDT Sun May 12 2024 .SYNOPSIS... High pressure keeps the area dry through the weekend and into the beginning of next week. The high then moves offshore Monday and increasing moisture supports an unsettled week with chances for showers and thunderstorms for much of the week. && .NEAR TERM /THROUGH TONIGHT/...
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Weak frontal boundary shifting southeastward through the forecast area this morning and will push off the coast by this afternoon. A relatively dry air mass is expected today with PWATs around 0.6-0.7 inches and dewpoints mixing back down into the 40s. Other than some passing cirrus clouds and a few cumulus during peak heating skies should be mostly clear and with a weak downsloping northwesterly flow, expect high temperatures to be warmer than Saturday with highs in the lower 80s. High pressure centered over the Mid-Atlantic and Carolinas tonight should yield favorable radiational cooling conditions but increasing clouds in the form of high and mid level clouds through the night ahead of the next upper trough to our west will prevent ideal radiational cooling. Overnight lows expected to be a bit warmer in the mid to upper 50s.
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&& .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
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Monday, an upper low pressure system over the Four Corners region will eject and push across the CONUS. This will lead to increasing southwesterly flow with strong moisture transport in the upper and mid levels as PWATs increase through the day. This will lead to increasing clouds, first over the CSRA and then into the rest of the forecast area. As a result, expect cooler highs in the CSRA, in the mid-70s and low 80s, in the eastern portion of the area. Forecast soundings do indicate a layer of near surface dry air and so while isentropic lift is expected to increase towards the end of the day on Monday, any precipitation should be light. With isentropic lift increasing overnight Monday, rain chances will continue to increase.
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&& .LONG TERM /TUESDAY THROUGH SATURDAY/... Ensemble suites show high probability (around 80 percent) that by Tuesday PWATs will increase to above an inch and a half. With a fairly robust shortwave moving through the area, expect widespread showers, although there is some question as to the exact evolution as models are indicating some drier air behind this shortwave and uncertainty to its timing as it will result from the ejection from the previously mentioned upper low. As far as an ingredient perspective, there remains at least some concern of the potential for severe weather, especially across the southern area where there is higher potential for destabilization but the overall shear profile would support organized storms. As we start to approach the timing for convective allowing models, there is also the potential for an upstream MCS to develop in the Deep South and move east, riding along the highest instability near the Gulf Coast, which may miss us to the south. While some drier air likely moves in Wednesday, ensemble means indicate moisture remains high enough to support scattered showers and storms, especially in the Pee Dee. Brief ridging expected to build back in briefly Thursday before another moisture surge expected Friday with LREF probability showing highest probability of destabilization in the CSRA. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/...
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High confidence in VFR conditions through the TAF period. Weak front pushing through the area this morning as high pressure builds over the area through tonight. Near calm winds will pick up from the northwest through the day before going light and variable to calm tonight. Mostly clear skies expected through today with some increasing higher and mid clouds overnight. Fog/stratus not a concern given dry air mass. EXTENDED AVIATION OUTLOOK...Showers and thunderstorms and associated restrictions are possible late Monday through Wednesday.
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&& .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$