Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
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106 FXUS62 KCAE 300008 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 808 PM EDT Mon Apr 29 2024 .SYNOPSIS... On Tuesday there will be a chance of thunderstorms in the afternoon with a low threat of severe weather. Broad ridging aloft will develop for the rest of the week limiting the extent of convection and allowing temps to rise above normal, then precip chances increase over the weekend. && .NEAR TERM /THROUGH TONIGHT/... Cumulus clouds over the area are dissipating as the sun sets this evening leading to mostly clear skies to begin tonight. As the upper ridge shifts to the east and moisture increases with southwesterly winds aloft. A line of showers and storms remains well to the west of the area as of 8pm, entering western Alabama. This line will continue to advance through the Deep South into tonight with forcing provided by an upper shortwave. All indications from HiRes guidance is our area remains dry through tonight with increasing clouds over the area downstream of these showers and storms to the west. Low temperatures remain a bit warmer tonight with the increasing clouds with lows in the upper 50s. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... The axis of an upper level ridge will shift further offshore on Tuesday. As the ridge shifts east, an upper trough will move across the Deep South. Convection associated with the trough is expected to weaken through the early morning hours Tuesday. Virtually no SREF members bring the convection into the forecast area before dissipating so we have kept PoPs out of the forecast. However it would not be the first time that overnight convection has held together despite no model guidance showing it. Either way the upper level trough will cross the forecast area on Tuesday. Divergence aloft, moisture advection through SW low level flow, and convergence along the previous day`s outflow boundary should promote convective development in the after noon hours. Low and mid-level lapse rates are supportive of thunderstorms but are not very steep. The interquartile range of sbCAPE values from the SPC HREF range between 400 to 1000 J/kg. Deep layer (0-6km Shear) values are around 20 kts with weak 850mb wind fields. This may limit the threat of organized convection. Thunderstorms should develop in the afternoon either scattered or focused along a possible remnant outflow boundary. There`s a low threat of severe weather given the modest lapse rates and wind fields. A slot of mid-level dry air in the afternoon suggests the biggest threat would be isolated downburst winds or small hail. As the trough shifts east in the evening expect the bulk of the thunderstorm activity to move out of the forecast area with some lingering convection possible into the night. Highs will be in the low to mid 80s Tuesday with lows in the upper 50s to around 60 degrees. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Drier air will move into the area for Wednesday as an upper level trough moves east of the area. PWAT values will still be around 1 inch and there may still be a few showers along the coastal regions where low level moisture is higher. But overall, convection should be suppressed by the dry air and warmer temps aloft. Global ensemble means favor ridging aloft over the Southeast through much of the long term. This along with generally southerly flow favors temperatures above normal with highs on Thursday and Friday in the mid to upper 80s with some locations possibly breaking 90 degrees. Over the weekend and into early next week, the overall pattern supports flattening the ridge. This could lead to a series of shortwaves moving over the forecast area. This in combination with PWAT values from 1.5 to 1.75 inches supports a chance of showers and thunderstorms each day through the remainder of the long term. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... Forecasting mainly VFR conditions through the period. Scattered clouds across the forecast area have almost diminished with the approach of sunset. Exception in across the western CSRA where satellite still indicates scattered mid clouds due to slightly better moisture. Expecting mostly clear conditions with only a few clouds in the low to mid levels for much of the night. In upper levels, some cirrus should stream eastward and across the region through the night. Better moisture moves in after sunrise Tuesday ahead of the next approaching rainmaker from the west. Skies will become more broken, with ceilings lowing into the mid to lower levels through the late morning and into the afternoon. Heights still forecast to remain vfr at this time, and most guidance seems to agree with that. Showers should remain west of the taf location through much of the taf period, with isolated to scattered showers possible developing and approaching all locations towards the end of the period. Have placed mention of vcsh late in all tafs. Light southerly winds overnight around 5 knots, then increasing up to 10 knots through the day Tuesday. EXTENDED AVIATION OUTLOOK...Restrictions possible in scattered thunderstorms Tuesday evening. Additional restrictions become possible again by Saturday ahead of another system. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$