Area Forecast Discussion
Issued by NWS Columbia, SC

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000 FXUS62 KCAE 182347 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 747 PM EDT Tue Jun 18 2019 .SYNOPSIS... Surface high pressure will extend from the Atlantic westward into the Gulf of Mexico through the rest of the week. North of this ridge, weak troughing will be in the forecast area. A series of upper-level troughs will affect the area through Thursday brining scattered to numerous diurnal thunderstorms. Upper ridging will bring somewhat drier and hotter conditions late this week and weekend. && .NEAR TERM /UNTIL 7 AM WEDNESDAY MORNING/... A southern stream shortwave trough crossing GA is now approaching the forecast area. Scattered showers and thunderstorms will become more widespread and a broken line of convection is moving into the CSRA. SPC has the northern and western portion of the forecast area outlooked in a marginal risk for severe weather. Instability is moderate, but 0-6 km shear is relatively weak, so the overall severe threat appears low. Isolated damaging winds are possible, but DCAPE values are marginal at 700 J/kg. Locally heavy rainfall is also possible with Precipitable Water around 2 inches. Convection will diminish as the shortwave shifts east tonight, but isolated showers will remain possible. Lows tonight will be in the lower 70s. && .SHORT TERM /7 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... Wednesday, expect scattered afternoon thunderstorms with high temperatures around 90 degrees. Though the deeper moisture will move east of the forecast area Wednesday, SW low level flow will still allow for diurnally driven convection. Recent model runs are now showing a weak shortwave moving into the forecast area late in the day. Given the better upper level support we have slightly increased PoPs. Particularly across the northern FA where lee-side troughing will be most prominent. Convection may linger into the evening as the shortwave passes through. A strong low level jet from 30 to 40 knots will keep winds up overnight and prevent fog. Overnight lows will be in the low to mid 70s. Thursday, an upper level trough will move into the eastern CONUS. Models are indicating the potential for moderate to strong instability as the vorticity maxima moves into the FA. 0-6 km bulk shear will also be strong for this time of year, around 30 knots. This indicates that organized convection is likely during the afternoon and evening. Steep mid-level lapse rates and strong shear suggest the main hazard will be damaging wind gusts. && .LONG TERM /FRIDAY THROUGH TUESDAY/... Drier air will be over the FA on Friday in the wake of an upper level trough. Downslope flow will also contribute to dry, warm weather. We expect highs to be a little warmer than guidance on Friday due to the downslope flow, ranging from the low to mid 90s. Any showers or thunderstorms that develop during the afternoon would be isolated at best. An upper level ridge will remain over the Southeast through much of the remainder of the long term with PWAT values above 1.5 inches. This pattern supports warmer than normal temperatures and mainly diurnal convection, aided by the timing of a few shortwaves moving over the ridge. Temperatures will warm late this week and into early next week with temperatures above normal. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... VFR conditions generally expected through midnight outside of any convection then possible stratus developing during the morning hours on Wednesday. Shortwave energy moving across GA has sustained convection across eastern GA which will move into our area during the 00z-05z time frame, impacting AGS/DNL 00z-03z and CAE/CUB/OGB 01z-04z. Possible thunderstorms will accompany brief heavy rainfall and possible wind gusts up to 25-30 knots. Otherwise light south to southeasterly winds expected through the overnight with a 20-25 knot low level jet helping to prevent fog formation. Inconsistent guidance suggesting stratus redevelopment late tonight but decided to go with persistence and include MVFR cigs in forecast at all terminals during the 09z-15z time frame. Winds will pick up from the southwest on Wednesday with speeds pushing into the 10 to 12 knot range after 18z. Scattered afternoon convection again possible with strong heating and abundant atmospheric moisture but timing and location uncertain so not including in this forecast issuance. EXTENDED AVIATION OUTLOOK...Southerly flow will continue pushing moisture into the area resulting late night/early morning fog/stratus through Thursday. Widespread convection possible Thursday into Thursday night as a cold front crosses the area. Isolated diurnal showers and thunderstorms possible Saturday and Sunday. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$

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