Area Forecast Discussion
Issued by NWS Atlanta, GA
Issued by NWS Atlanta, GA
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889 FXUS62 KFFC 181558 AFDFFC Area Forecast Discussion National Weather Service Peachtree City GA 1158 AM EDT Wed Sep 18 2024 ...New Update Cloud Coverage... .UPDATE... Issued at 1148 AM EDT Wed Sep 18 2024 Forecast is generally on track. However, have bumped up cloud coverage for today starting with satellite derived coverage, then interpolating through an NBM/NBM 90th percentile blend, then back to the original forecast by 00Z. /SEC && .SHORT TERM... (Today through Thursday) Issued at 443 AM EDT Wed Sep 18 2024 This morning, the post tropical low has drifted over eastern Tennessee. Calm winds within the relatively moist airmass may produce areas of patchy dense fog that will last until daybreak. Later today, a surface low is expected to spin up across central Georgia along a boundary. Diurnally driven showers and possibly a thunderstorm are expected this afternoon across far northeastern Georgia and far central eastern Georgia. The best chance for precipitation will be in northeast Georgia, while the best instability, and thus thunderstorm chances, will be focused further south across eastern central Georgia. However, there remains some uncertainty over how far west storms could fire this afternoon in this area. Temperatures will be a bit cooler across north Georgia where more cloud coverage is expected to linger today. Temperatures in this area will max out in the low 80s while areas further south will climb into the upper 80s. To our west, ridging aloft will begin to build in this evening and into early Thursday. As the ridge helps usher the low pressure off the eastern seaboard, skies will begin to clear overnight. Overnight lows will drop into the 50s in the northeast Georgia mountains with 60s elsewhere. Tomorrow is expected to be dry with a low end chance of rain in our furthest northeast counties. Under mostly sunny skies, high temperatures will climb into the upper 80s for most locations outside of the north Georgia mountains where temperatures will remain generally in the 70s to low 80s. KAB && .LONG TERM... (Thursday night through Tuesday) Issued at 443 AM EDT Wed Sep 18 2024 Key Messages: - Long term remains dry. Very little opportunity for rain until the end of the forecast period, and chances still remain low. - Increasingly looks like the end of the week into the weekend could be quite warm, with temps reaching into the upper 80s and even 90s. Forecast Discussion: The largest driver of change over the past 24 hours of the long term seems to be the difficulty the models seem to be having with the low pressure system over the area. This isn`t surprising - for all intents and purposes, this is behaving like a cut off low, and models will always struggle with these features in the absence of strong upper level flow to push them along. Both the EPS and the GEFS (alongside their deterministic counterparts) have seen a shift towards bringing this low and surface low off the coast and then developing a bit as it pushes towards the northeast. Without anything to change our airmass, it is allowed to sit for several days and continue to modify and heat, bringing day time highs into the 80s and 90s by the weekend. With this low off the coast, a bit more uncertainty has been introduced over the weekend. The surface high expected to develop to the north takes a bit more time to push into the area if the surface low off the northeast is in place, which in turn prevents us from being "wedged" as fast. The EPS is more in favor of this scenario, keeping us warmer. The deterministic GFS and some of the GEFS members also show this, but some of the GEFS hangs on to the idea of the wedge coming in a bit faster, which would certainly cool us a bit more than what is in the forecast for Sunday and Monday. This forecast package will lean towards the wedge being delayed a bit, as the guidance of late has struggled with the amplitude of these lows off the coast being a bit underdone, so forecast temps into Sunday remain in the upper 80s and 90s. Temps cool down after this as it does still look like a CAD airmass will move in. Rain chances with this still appear low. After this, attention may turn to the tropics depending on how development of a feature there begins in the next few days. Want to note that despite what one model is showing, there is still considerable spread among the wider ensemble, showing anything from almost no development to systems that are just about anywhere in the Gulf. Uncertainty remains very high overall. Lusk && .AVIATION... (12Z TAFS) Issued at 626 AM EDT Wed Sep 18 2024 VFR conditions currently but periods of IFR will be possible at northern sites beginning between from 12Z to around 15Z. MVFR vsby`s from 3-5SM are also possible at KRYY around sunrise. Tonight, KMCN/KCSG will see MVFR vsbys from 06-10Z. Winds are calm to VRB for much of the TAF period, but will be around 5KT or less out of the NW during the day. Winds will shift to the NNE after 02Z and will shift back to the NNW after 17Z at KATL. //ATL Confidence...12Z Update... Medium confidence on IFR cigs this morning and MVFR vsbys overnight. High confidence on remaining elements. KAB && .PRELIMINARY POINT TEMPS/POPS... Athens 62 85 64 87 / 10 10 0 0 Atlanta 64 87 66 88 / 0 0 0 0 Blairsville 59 80 58 83 / 10 10 0 0 Cartersville 62 87 62 90 / 0 0 0 0 Columbus 66 88 68 90 / 0 0 0 0 Gainesville 63 84 64 86 / 10 10 0 0 Macon 65 87 66 88 / 10 0 0 0 Rome 63 88 62 91 / 0 0 0 0 Peachtree City 62 86 64 88 / 0 0 0 0 Vidalia 67 87 67 86 / 10 10 0 0 && .FFC WATCHES/WARNINGS/ADVISORIES...None. $$ SHORT TERM...SEC LONG TERM....Lusk AVIATION...KAB