Area Forecast Discussion
Issued by NWS Atlanta, GA
Issued by NWS Atlanta, GA
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427 FXUS62 KFFC 191500 AFDFFC Area Forecast Discussion National Weather Service Peachtree City GA 1100 AM EDT Thu Sep 19 2024 .UPDATE... Issued at 1056 AM EDT Thu Sep 19 2024 Updated the forecast to adjust for obs with temperatures slower to warm up today with some of the lingering cloud cover. Clouds are beginning to scatter out this morning and any rain chances remain confined to the northeast GA mountains. && .SHORT TERM... (Today through Friday) Issued at 411 AM EDT Thu Sep 19 2024 This morning, a low pressure system is sitting over South Carolina with a stationary boundary over central Georgia. With upper level ridging building in to the west over the Plains, the low will eventually be shifted off the eastern seaboard today and the stationary boundary will progress southward over northern Florida. This afternoon and early evening, northeast Georgia could see a few showers on the backside of the low before the system makes its exit later. With SBCAPE between 500-1000 J/kg and bulk shear ~25KT, an isolated rumble of thunder is possible, particularly over areas of mountainous terrain. The biggest story in the short term will be the high pressure building in resulting in above average surface temperatures, especially across north Georgia. Today, temperatures will reach the mid to upper 80s with some locations across north Georgia seeing temperatures top out 5 degrees warmer than climatology. Locations further south will be closer to average. Temperatures today will be moderated a bit by lingering cloud coverage due to the moisture wrapping around low pressure system over South Carolina. Overnight lows will be mild for this time of year, running in the mid to upper 60s (about 5 to 7 degrees above normal). Tomorrow, with the low well to the east, a wedge begins to become established and will be accompanied by mostly sunny skies. Temperatures tomorrow will be warmer than today, with most locations in the upper 80s. A few locations across the area will reach the 90 degree mark. Highs tomorrow will be running as high as 10 degrees above normal for areas across north Georgia and 5 degrees above normal for many places across central Georgia. KAB && .LONG TERM... (Friday night through Wednesday) Issued at 411 AM EDT Thu Sep 19 2024 Key Messages: - Warm temperatures that will be 8-13 degrees above average in parts of north Georgia through the weekend. - Complex upper air pattern combined with tropical uncertainty make for a difficult mid to end of week forecast next week. Forecast Discussion: The main meteorological players at the beginning of the long term will be a low pressure off the shore of New England that models have settled in on forming, a mostly stagnant airmass over us, and a developing surface high well to the north over the Canadian maritime. Into Saturday, this low doesn`t look like it will have pushed any cooler air into us, so our drier air will continue to heat bringing temperatures into the 90s in some locations. This low slowly slides to the south on Sunday as the surface high seeps around it into the northeast. The models show signs of a surface boundary push down the Appalachians, but for now do not bring it in. This may be the first place where we can discuss a little uncertainty, as models can struggle with the timing and strength of these airmasses as they filter down the Appalachians, but given the unusual location of the surface high, there are reasons to believe CAD processes may not be as dominate yet. More uncertainty introduces itself after this, with more players entering the forecast. A cut off upper low currently over California is expected to eject into the Plains developing an attendant surface low. The exact timing, track, and even strength of this low has decent uncertainty, and how close it gets to the CWA will have implications for moisture draw from the Gulf and potentially whether the wedge may run into additional challenges moving into the area. The surface low off the coast is expected to continue diving south, allowing the wedge to attempt to move into the area, but the high pressure to the north of the low does appear to begin to weaken a bit, decreasing the pressure gradient and the potential strength of the CAD. So, this creates some spread in the temperature forecast. NBM 10th and 90th percentiles are about 5-7 degrees apart Monday and Tuesday across the CWA, higher in the north and northeast. Adding even more fuel to the fire by the end of the long term will be the tropics. Generation of a broad low off central America continues to look likely. While the probability that a tropical system forms from this is increasing, there are still a wide variety of possibilities ensembles continue to show in terms of timing, strength, and position of any system, if one is even able to form. Broad lows can help spark the formation of these systems by providing a focus for convection and vorticity maxima, but organization of these broader systems can sometimes be a struggle for a variety of reasons. Once again, don`t pay attention to single runs of models. Take clues from the broader ensemble, which still highlights a wide range of possibilities. Lusk && .AVIATION... (12Z TAFS) Issued at 619 AM EDT Thu Sep 19 2024 VFR conditions for all terminals through TAF period. FEW/SCT IFR from 12-13Z at metro sites. Will be scattering out not long after sunrise to SCT 3-4kft through the day before becoming FEW250 overnight. FEW 4kft with cu field tomorrow after sunrise. Light winds at 5KT or less will be out of the NE. //ATL Confidence...12Z Update... Low confidence on IFR. High confidence on remaining elements. KAB && .PRELIMINARY POINT TEMPS/POPS... Athens 65 88 64 89 / 10 0 0 0 Atlanta 67 88 67 90 / 0 0 0 0 Blairsville 60 83 60 85 / 10 0 0 10 Cartersville 65 90 64 92 / 0 0 0 0 Columbus 69 90 68 91 / 0 0 0 0 Gainesville 65 87 65 89 / 10 0 0 0 Macon 66 88 66 90 / 0 0 0 0 Rome 64 91 63 92 / 0 0 0 0 Peachtree City 65 88 64 89 / 0 0 0 0 Vidalia 68 88 67 88 / 0 0 0 0 && .FFC WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Hernandez LONG TERM....Lusk AVIATION...KAB