Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
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570 FXUS62 KCAE 171840 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 240 PM EDT Fri May 17 2024 .SYNOPSIS... Chances of showers and thunderstorms will increase this afternoon as a weak system begins to slowly cross the region with shower and thunderstorm chances likely lingering into Sunday. Cooler and drier air moves in for Monday and Tuesday with temperatures rebounding during the middle of next week as another ridge moves in from the west. && .NEAR TERM /THROUGH TONIGHT/... Positive tilted upper trough over the central/southern Plains will be moving east toward the Mississippi River overnight. Weak surface low over the Gulf coast area will move northeast into SC overnight. Southwest flow aloft continues across GA and SC overnight ahead of trough. Deeper moisture axis over AL/west GA this afternoon seen on water vapor will be shifting northeast into SC by early this evening. Precipitable water is expected to be > 1.75 inches, perhaps near 2 inches across the CSRA/southern or eastern Midlands overnight. Convection at the moment is focused across southern AL into south central Ga near a stationary front. As the surface low moves northeast toward the area, expect this front to lift north and showers should spread northeast into the CSRA and the Midlands by early evening. Mid level clouds have been considerable through the morning and convective inhibition remains, but breaks in the overcast developing across the central and north Midlands and temperatures are rising into the lower 80s. Model soundings show steepening low level lapse rates through the afternoon then weakening. Expect at least some weak instability so chance thunderstorms probability less threat later this evening. Weak short wave trough triggers in southwest flow aloft along with warm advection/increasing isentropic lift overnight should lead to numerous showers. Think the focus will be in the CSRA and south Midlands late afternoon and early evening with potential for locally heavy rain/higher precipitable water. Light precipitation to the north in mainly isentropic lift diminishing overnight. Overnight lows in the mid to upper 60s/near 70. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... Positively tilted trough will continue to slowly push eastward towards us and should be centered across the lower MS Valley by tomorrow morning. Strong flow at 500 hPa is expected to create strong shear profiles, and CAMs are generally showing some sort of MCS structure to our southwest, but how far north this gets and how fast it will be is in question. Generally, guidance has struggled with speed and placement of convective structures like this in recent weeks. So there is uncertainty about this, but confidence is high that an MCS of some sort will be in central GA at the start of this period. Ahead of this, rich moisture should favor some instability, and given the shear in the atmosphere, strong to marginally severe storms are again possible depending on the location of this convection. Thinking the best chance for this is in the southern FA, but timing and severity is hard to piece together right now. Think it`ll be approaching or through our FA by late morning, and if this happens, it opens the door for some afternoon sunshine and another round of thunderstorms in the central and northern FA. While the strongest shear will be to our east, robust instability is possible where we see sunshine tomorrow afternoon so we`ll need to watch for strong strong storms along an amorphous surface front across the northern part of SC. Highs should generally be in the mid 80s but upper 80s are possible for those that see more sunshine. Showers will probably hang around into Saturday night as the trough approaches with lows in the mid 60s expected. On Sunday, more showers and embedded thunderstorms are possible as the trough approaches and pushes over the region. Some uncertainty is present with where the surface low and resultant convergence develops, adding some overall uncertainty to rain coverage Sunday afternoon. But confidence is high that we`ll see scattered to numerous showers across much of the area, with highs in the upper 70s and low 80s. Showers should clear out on Sunday night as a back door front pushes through and pushes low PW air into the area. && .LONG TERM /MONDAY THROUGH FRIDAY/... Confidence continues to remain fairly high in the long term period. Cool and dry air is expected to remain in place on Monday, with highs well below normal near 80s. Modification quickly begins on Tuesday as high pressure shifts to our east and ridging aloft begins to build. This should carry highs back into the upper 80s and low 90s by Thursday. Another cold front is forecast to approach by the Thur/Fri timeframe, with the possibility of showers and thunderstorms in the afternoon in association with that. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... Restrictions developing by early evening as showers move into the region. VFR at the moment with mid level ceilings dominating. Moisture will be increasing late this afternoon and overnight as weak low pressure moves toward the area from the Gulf coast. Radar is showing showers over central Ga. These showers will move northeast into the region by early evening. guidance is consistent with MVFR ceilings/visibility in showers this evening and possible IFR ceilings by 06z. Focus for any heavy rain during the 21z-04z period. Widely scattered/scattered thunderstorms possible and think mainly from AGS/DNL to OGB but confidence low at this time due to overall limited instability. Showers dominate by mid evening and overnight as any instability weakens but coverage increasing so restrictions in visibility possible. MVFR conditions after 12z Saturday with a few showers in the area. Winds have been light and variable this afternoon, but favor light south to southwest. EXTENDED AVIATION OUTLOOK...Increasing confidence in restrictions in showers and thunderstorms continuing through Sunday night. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$