Area Forecast Discussion
Issued by NWS Atlanta, GA
Issued by NWS Atlanta, GA
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774 FXUS62 KFFC 291451 AFDFFC Area Forecast Discussion National Weather Service Peachtree City GA 1051 AM EDT Sat Jun 29 2024 ...Morning Update... .UPDATE... Issued at 1047 AM EDT Sat Jun 29 2024 No significant changes to the near term forecast this morning. Low clouds continue to slowly lift, slower than models indicated. Therefore will expect thunderstorms to also have a slower start than CAMs may indicate. Moisture is much deeper today, reaching to 500 mb in the sounding. Thunderstorm chances will be more likely with CAPE of ~1500 J/Kg. A few storms may become strong and water-loaded and could develop gusty winds, frequent lightning, and efficient rainfall. Temperatures look mostly on track if slightly below forecast due to continued cloud cover. This should clear out further over the next hour or so. Still expected heat indices near 100 to 104 South and East of I-20 and I-85. && .SHORT TERM... (Today through Sunday) Issued at 403 AM EDT Sat Jun 29 2024 At a glance: - Afternoon showers and thunderstorms each day. - Increasing heat indices through the weekend. The weak upper level trough across Central GA has become diffuse, and a rather narrow E/W upper ridge will build in its place through the weekend. Shower and thunderstorm activity is expected to remain scattered and diurnally driven through the short term. Precipitable water values are forecast to remain very high through the period was well, with values between 2 and 2.25". The dry layer aloft centered around 450-500 millibars with gradually moisten through the weekend. Late yesterday evening, showers and isolated thunderstorms spread north from the Thomaston area into the Atlanta metro area. This activity has been on a very gradual weakening trend through the night, with the last lightning detected before midnight. CAPE values across the area have continued to decrease, although there has been a slight uptick over the past hour or two from the S Atlanta metro area to Columbus and Macon. Shower and thunderstorm activity is expected to develop this afternoon across the area, with the best chances across the NW third of the County Warning Area (CWA). Have adjusted PoPs down a bit from the NBM consensus due to the expected strengthening of the upper ridge and the lingering dry layer aloft. For Sunday, have gone with 50 to 60 percent PoPs across the area with slightly lower PoPs across the central portion of the CWA (directly beneath the upper ridge). Due to the fairly slow storm motion and high precipitable water, locally heavy rainfall is possible in the heaviest showers and storms. Once again, storms are expected to remain below severe limits, although precipitation loading may produce strong wind gusts in the heaviest storms. High temperatures this afternoon should range from near 80 in the highest terrain of the NE mountains to the mid 90s across the SE half of the area. After adjusting afternoon dew points to account for mixing, heat indices E of Macon should top out around 103 today. Low temperatures tonight will range from the mid 60s on the highest ridges of the NE to the lower to mid 70s elsewhere. With hotter ambient temperatures on Sunday (mid 80s in the NE mountains to mid 90s elsewhere) and slightly higher surface dew points, heat indices may reach 105 to 107 From Athens to Macon and points E. If this trend continues, a Heat Advisory may be needed in that area. /SEC && .LONG TERM... (Sunday night through Friday) Issued at 403 AM EDT Sat Jun 29 2024 Beginning the long term period with Monday, the dampened 500 mb ridge axis continues over much of the south with Georgia on the eastern periphery. Meanwhile to the north of the ridge, several troughing features attempt to deepen as they move east every couple of days through the pattern. With us being in a northwesterly flow due to this, there is just enough vorticity that makes it to Georgia to cause daily rain chances through Wednesday into Thursday. Models are also forecasting PWATs at 2+ inches through the end of next week which are above the 90th percentile for this time of year (1.80- 1.90"). This in combination with the pushes of vorticity into the area results in increased rain chances through the long term. It is also summer which means CAPE values are forecasted to be between 1000-2000 J/kg every afternoon and evening resulting in increased thunderstorm chances too. Overall a very summer like pattern. Despite the increased rain chances most afternoons, accumulations over the next 7 days range from 0.10"-1.5", so overall still not a lot of rain. Towards the later half of the long term period (Saturday into Sunday), models are indicating a break down of the ridging pattern as a trough dips into the mid MS valley bringing a what looks to be a frontal pattern. Time will tell how this pattern evolves since it is still 7 days out. With the increased moisture, dewpoints will also be increased with values in the mid 70s through the beginning of next week. This in addition to the temps reaching into the mid to upper 90s will result in heat indices being in the 100-106 range Monday. Only minor relief from these heat indices is expected on Tuesday into Wednesday where heat indices are currently forecasted below 100, as dewpoints dip below 70 for a short time period. Moisture surges again Wednesday returning us to heat indices in the 100-105+ range through the remainder of the extended. Again overall a very summer like pattern for much of Georgia as we begin the month of July with above average temps. Hernandez && .AVIATION... (12Z TAFS) Issued at 722 AM EDT Sat Jun 29 2024 Shower activity has continued to slowly weaken around and N of the Atlanta metro area. Low cigs are expected to expand over the next hour or two (along with patchy, mostly light fog near recent rain areas), with cig heights of around 600-800 feet. Low clouds will lift and thin later this morning, followed by afternoon shower and thunderstorm activity. Have adjusted the start time later to account for morning low clouds and convective debris along with lack of dynamic support. Light winds will become mostly SW during the day. Wind speeds will remain light outside of heavier showers and storms. //ATL Confidence...12Z Update... Medium for morning low cigs and vsbys along with start time of afternoon tstms. High for other elements. SEC && .PRELIMINARY POINT TEMPS/POPS... Athens 74 95 73 90 / 30 50 40 40 Atlanta 75 94 75 93 / 30 50 30 30 Blairsville 69 88 67 86 / 30 60 20 30 Cartersville 73 94 70 93 / 20 50 20 20 Columbus 75 96 75 96 / 30 60 30 40 Gainesville 75 93 74 90 / 30 50 20 30 Macon 74 96 73 94 / 20 60 40 50 Rome 75 95 72 93 / 20 60 10 10 Peachtree City 73 95 72 94 / 30 50 30 30 Vidalia 75 96 76 94 / 20 60 50 70 && .FFC WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...SEC LONG TERM....Hernandez AVIATION...SEC