Area Forecast Discussion
Issued by NWS Columbia, SC

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000 FXUS62 KCAE 190846 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 346 AM EST Tue Feb 19 2019 .SYNOPSIS... A wet pattern will occur through the week. A continued southwest upper flow, with a series of embedded upper disturbances and resultant surface waves, combined with abundant atmospheric moisture will bring rain at times. A cold front will cross the area Sunday with dry high pressure returning Monday. && .NEAR TERM /THROUGH TONIGHT/... High pressure will ridge into the forecast area from the north through tonight. The models indicate weak isentropic lift over this wedge ridge becoming stronger late tonight. There will be a series of fast moving weak mid-level shortwave troughs. The models and observation trends support dry low levels through today and expect mainly periods of sprinkles. Deeper moisture and greater isentropic lift support a little more significant rain late tonight. The NAM, GFS, ECMWF, plus SREF guidance indicate rain amounts less than one-quarter of an inch. We followed the lower temperature guidance because of the wedge pattern today. Followed the guidance consensus temperature tonight. The MAV and MET MOS support northeast wind 10 to 15 mph. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... High pressure ridging in from the north will continue the wedge pattern across the region Wednesday. There may be some weakening over the coastal plains and eastern Midlands Wednesday night, allowing for warmer temperatures. Still expect cloudy, damp and cool conditions for Wednesday. Went closer to the cooler guidance for highs in the 40s with low to mid 50s across our southern tier counties. If the wedge weakens across the south/east, temperatures may be able to climb into the 60s there. There will be a continuation of light rain/drizzle into Wednesday night as moisture continues to glide up and over the colder surface airmass. Late Wednesday night as another system pushes towards the region from the west, the wedge may be able to begin weakening, but confidence is low at this time as to the exact timing. We kept temperatures nearly steady in the lower 40s north to lower 50s south. The frontal boundary will linger in the area Thursday continuing a chance for rain. Models are not yet in agreement on the exact location of the front on Thursday, but finally pushes it south of the CSRA Thursday night. Guidance still indicated a large range for temperatures on Thursday. The NAM holds the front over the central Midlands while the GFS and ECMWF push the front farther north. Have indicated cooler temperatures for the northern Midlands...in the mid to upper 50s. We kept unseasonably warm temperatures south of the front from central SC into the CSRA with highs in the 70s to near 80. The best chance for rain will be across the northern and western Midlands closer to expected frontal position. && .LONG TERM /FRIDAY THROUGH MONDAY/... The chance for rain will continue Friday and Saturday with a frontal bounday to our south and high pressure wedging in from the north. Another front is forecast to move through the area on Sunday with a better chance for rain. A dry airmass is expected to arrive in the wake of the front Sunday night into Monday. Temperatures in the longer term remain difficult to pin down due to the potential for additional weaker cold air damming to move back into the area at Friday/Saturday. Have continued to favor a model blend for temperatures through the weekend, which keeps the colder air north of the Midlands. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... Expect mainly VFR ceilings this morning but lowering ceilings later this afternoon and especially tonight. Low-level wind shear may become an issue tonight. High pressure will ridge into the forecast area from the north through tonight. The models indicate weak isentropic lift over this wedge ridge becoming stronger late tonight. There will be a series of fast moving weak mid-level shortwave troughs. The models and observation trends support dry low levels through much of today and expect mainly periods of sprinkles with little effect on visibility. Deeper moisture and greater isentropic lift will occur late this afternoon and evening and especially late tonight. We followed the GFS LAMP with MVFR conditions developing late this afternoon and evening. The NAM and GFS MOS support surface wind northeast about 10 knots. The models indicate a strengthening low-level jet over the wedge ridge tonight and based on the NAM we included low-level wind shear in the terminal forecasts. EXTENDED AVIATION OUTLOOK...Precipitation and flight restrictions are expected at times through Saturday as a series of weather systems move through or near the area. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$

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