Area Forecast Discussion
Issued by NWS Columbia, SC

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000 FXUS62 KCAE 221851 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 251 PM EDT Sun Oct 22 2017 .SYNOPSIS...
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A cold front will bring a chance of showers and thunderstorms late tonight through early Tuesday, followed by cooler temperatures for mid week. Fair with a warming trend late week. Next weather system may approach by next weekend.
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&& .NEAR TERM /THROUGH TONIGHT/...
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Upper level ridge over the area will be shifting off the coast early this evening. Low level moisture will be increasing through the overnight. Radar indicating a few showers developing in the south coastal plain this afternoon as the moisture flux develops. Air mass remains mainly stable across the CWA this afternoon with mid level cap. Showers will likely weaken in the short term as they track inland. Expect overall diurnal weakening of showers after sunset. However...light rain expected to increase especially in the CSRA late tonight as moisture flux and isentropic lift increases. This is suggested by the high mos pops after 06z across the south CWA. Lowest pops overnight in the Pee Dee as moisture flux remains focused to the south of that region. Warm afternoon with highs in the low to mid 80s. Forecast overnight lows near mos although in areas that remain dry expect temperatures on the warm side...near 70 degrees.
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&& .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/...
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A mid-level shortwave trough will move across the Southeast Monday as it lifts northward and gets absorbed into the broad upper level trough. Strong moisture advection and isentropic lift will allow an area of showers to develop early Monday morning. We expect these showers to move northward through the morning in the southerly flow. Isentropic lift diminishes late Monday morning and there may be a break in shower activity before a cold front moves in during the afternoon. Monday afternoon, a cold front will push into CSRA and move eastward through the Midlands during the late afternoon or evening. High confidence in most of the area getting some rainfall out of the system. Short range ensembles and model guidance suggests around one inch of rainfall over the area. All showers will be east of the forecast area by Tuesday morning. Strong surface forcing along/near the front and strong divergence aloft will allow thunderstorms to develop in the band of convection. Strong 0-3 km shear, with values greater than 35 kts, poses a threat for severe weather. The limiting factor will be surface based instability. Showers during the morning and overcast skies will limit low-level destabilization. However continued warm, moist advection into the region may be enough to compensate for the weak diabatic heating. If the low levels are able to destabilize then damaging wind gusts in bowing lines of thunderstorms will be the main threat. Given the moderate helicity and strong 0-1 km shear expected we also cannot rule out a brief tornado.
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&& .LONG TERM /TUESDAY THROUGH SUNDAY/...
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An deep upper trough will dig into the Southeast through mid- week. This will bring dry weather and below normal temperatures into the area. The trough exits the region late in the week as surface high pressure moves offshore. This will allow temperatures to warm and moisture to return for the weekend. Another cold front will approach the region near the end of the long term bringing back chances for precipitation.
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&& .AVIATION /18Z SUNDAY THROUGH FRIDAY/... Expect mainly VFR conditions through the TAF period. High pressure aloft and at the surface will continue to dominate with just a small moisture increase in a light easterly flow into today. Low-level flow turns more out of the east through the day, which will help to bring additional Atlantic moisture to the region. Through early morning though, still only expecting to have some mid and high-level cloudiness moving through the cwa. Conditions remain dry into early afternoon, then the models show weak isentropic lift across the southern cwa. Conditions generally vfr through 00z at all sites, then ceilings may begin to lower down to mvfr between 00z-06z, with ifr conditions possible in light rain after 06z. EXTENDED AVIATION OUTLOOK...A frontal system may bring widespread restrictions in showers tonight into Tuesday, with thunderstorms possible Monday and Tuesday. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$ SYNOPSIS...99 NEAR TERM...99 SHORT TERM...99 LONG TERM...99 AVIATION...99

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