785 FXUS62 KFFC 101933 AFDFFC Area Forecast Discussion National Weather Service Peachtree City GA 333 PM EDT Sat Jul 10 2021 .SHORT TERM /Tonight through Sunday Night/... Northwesterly upper level flow continues across north and central Georgia behind a 500 mb trough positioned near the Mid-Atlantic coast. However, a transition in the flow aloft is anticipated tonight as as the trough over the mid-Atlantic flattens out and another trough to the northwest digs southward into the midwestern CONUS. Southwesterly flow upper level flow is thus expected to set up by Sunday and remain through the remainder of the weekend. At the surface, a stationary front is stalled north of the forecast area. As the upper trough moves into the midwest and develops into a closed low, the stationary front will lift to the north and a cold front extending from the low will move eastward towards the Mississippi Valley region. Meanwhile, the Bermuda high will begin to shift westward towards the Mid-Atlantic coast through the remainder of the weekend, allowing the low-level flow to take on a more southerly component. This synoptic setup will allow for increased moisture advection from the Gulf of Mexico over much of the region, with dewpoints forecast to reach as high as the mid 70s and precipitable water values anticipated to increase to 1.75-2 inches. Scattered showers and thunderstorms are ongoing across roughly the eastern half of the forecast area as a weak upper disturbance traverses the upper level flow. Isolated, diurnally driven convection has also begun to redevelop over west Georgia. As a result, high-end chance PoPs are expected to persist through the remainder of the afternoon before diminishing after sunset. Hi-res model guidance is inconsistent in handling convective development on Sunday. However, considering the increasing moisture, scattered to numerous showers and thunderstorms are forecast during the peak heating hours tomorrow across the area, SBCAPE values this afternoon will be as low as 1500 J/kg in west- central Georgia and as high as 3500 J/kg in east-central Georgia, Ample destabilization is expected across the area Sunday, as well. With the stationary frontal boundary positioned well to the north of the forecast area, there will be little shear to speak of this afternoon and tomorrow. Mid-level lapse rates are also expected to remain marginal, at mainly less than 6.0 C/km. As a result, an organized threat for severe weather is not anticipated today, although isolated storms may become strong to severe. Stronger storms will be capable of producing gusty winds frequent lightning. Furthermore, with high PWATs and weak boundary layer flow, slow- moving stronger storms will likely produce heavy rainfall and a potential for localized flooding. Considering the ample atmospheric moisture, afternoon highs are expected to be mainly 1-4 degrees below climatological normals, ranging from the mid 80s to low 90s, and morning lows are expected to be 2-5 degrees above climatological normals, ranging from the upper 60s to mid 70s. King .LONG TERM /Monday through Saturday/... Typical Georgia summertime weather expected with remarkable consistency over the long term period and beyond with afternoon highs in the mid 80s to low 90s, overnight low temps and dewpoints hovering around 70 degrees, PWATS steadily between 1.5-2", and a roughly 50-70% chance of afternoon diurnal showers and thunderstorms at any given location. Synoptically, the Bermuda High over the western Atlantic will remain steadfast, with an upper-level low over the Ozarks stalling and quickly occluding and shifting northward at the start of next week, taking any hope of an airmass change with it. The broad fetch of low- level southerly moisture will fuel diurnal showers and storms each afternoon. With so much moisture throughout the vertical profile and minimal upper-level support/dynamics, overall severe thunderstorm chances will be low outside of some anomalous water-loaded downbursts in isolated locations. Rather the main concern should be training or slow moving storms producing 2-3" of rain in isolated locations leading to localized nuisance flooding. Thiem && AVIATION... 18Z Update... Scattered convection has developed and is expected to persist through the afternoon and evening, diminishing after sunset. As a result, VCSH will run until 00Z while a TEMPO group for TSRA extends over the most likely time window, from 18-21Z. Primarily VFR conditions are in place across north and central Georgia, with BKN ceilings between 035-050, which should persist through the afternoon before scattering by 00Z. Scattered MVFR level clouds are possible on Sunday morning after 12-13Z. Winds will be W through the afternoon at 6-10 kts shifting to SW at 3-6 kts overnight, with the exception of gusts associated with any SHRA/TSRA. //ATL Confidence...18Z Update... Medium to high confidence on all elements. King && .PRELIMINARY POINT TEMPS/POPS... Athens 71 88 70 89 / 30 60 50 60 Atlanta 71 86 71 87 / 30 60 40 70 Blairsville 65 82 66 81 / 40 70 60 80 Cartersville 70 87 70 87 / 30 60 50 70 Columbus 72 89 72 90 / 30 50 40 70 Gainesville 70 86 70 87 / 30 70 50 70 Macon 71 90 71 91 / 30 60 40 60 Rome 71 87 71 86 / 40 60 50 80 Peachtree City 70 86 70 87 / 30 60 40 60 Vidalia 73 89 72 89 / 30 60 40 60 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...King LONG TERM....Thiem AVIATION...King