Area Forecast Discussion
Issued by NWS Atlanta, GA
Issued by NWS Atlanta, GA
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006 FXUS62 KFFC 070612 AFDFFC Area Forecast Discussion National Weather Service Peachtree City GA 212 AM EDT Sun Jul 7 2024 ...New 06Z Aviation Discussion... .SHORT TERM... (This afternoon through Sunday) Issued at 229 PM EDT Sat Jul 6 2024 Key Messages: - Scattered afternoon and evening thunderstorms may produce efficient rainfall rates and isolated wind gusts near 40 mph today and Sunday. - Hot and humid conditions will continue in the region through Sunday. This Evening and Tonight: A weak stationary frontal boundary was positioned near the Interstate 20 corridor this afternoon. Thunderstorms were ongoing along and south this boundary, and they should continue (with a gradual southward drift) into this evening. Poor mid level lapse rates (5.5 C/km or less) and a lack of shear (generally less than 15 kt) suggest that severe weather is unlikely today. The strongest storms may however generate hefty rainfall rates (1-3 inches per hour), frequent lighting and isolated wind gusts near 40 mph. Our 12Z sounding indicated a PW values of 2.13 inches, well above the 90th percentile for early July. Heat remains a concern this afternoon and the Heat Advisory is in place for portions of central and northern Georgia through 8 PM. Widespread heat index values in the 102-107 degree range have been observed, and isolated spots may approach 109 degree before either storms arrive or diurnal heating ends. Today`s rainfall and the high dewpoints could lead to patchy fog development early Sunday morning. For the fog to have a chance to form the region will need to see good clearing and radiational cooling tonight. The degree to which this will occur is iffy, though we have included some patchy fog in our official forecast for Sunday morning. For Sunday: The primary decision point for Sunday was whether or not a Heat Advisory will be needed for portions of central Georgia. Surface dewpoints should remain high (mid to upper 70s) in the region and this will keep ambient conditions unpleasantly muggy. It will also significantly prop up heat indices. However, afternoon high temperatures look like they may be 1-3 degrees cooler compared to Saturday`s highs. Cloud cover, afternoon showers and thunderstorms, and a slight decline in 850 mb temperatures should be the main factors behind these temperatures declines. Given these considerations peak heat index values should peak in the 100-106 degree range Sunday afternoon. While this may have patches of the area flirting with the 105 degree threshold for a Heat Advisory for a couple of hours, it doesn`t appear sufficient to warrant an area wide advisory. Thus we are forgoing the issuance of a Heat Advisory for Sunday at this time. This decision will be reevaluated this evening and early Sunday morning. There is a 40% chance that a Heat Advisory will be issued for a portion of central Georgia by a later shift. As mentioned above, thunderstorms will be a concern Sunday afternoon and evening. The front draped across the region today should washout somewhat on Sunday. This will limit low level support for thunderstorms and favor diurnally driven convection that is less predictable in terms of location. It should also allow better precipitation chances to spread back into northern Georgia (a trend evident in the 12Z HREF guidance). Small mid level temperature declines may allow 700-500 mb lapse rates to creep towards 6.0 C/km Sunday afternoon (slight improvement but still poor for severe weather). Effective shear for storms to work with should be similar to today (generally 20 kt or less). Given these considerations severe weather is unlikely Sunday. PW values near 2.0 inches will remain in the region and this should favor efficient rainfall rates (1-2.5 inches per hour) and precipitation loading (for downburst winds). Thus with the strongest storms we can`t rule out isolated gusts near 40 mph and localized rain totals of 2 inches. Albright && .LONG TERM... (Monday morning through next Friday) Issued at 229 PM EDT Sat Jul 6 2024 Typical summertime conditions will persist through the long term forecast. Hot daily temperatures in the upper 80s to mid 90s accompanied by triple digit heat index values and afternoon storm chances are expected through the end of the period. As high pressure over the forecast area wanes through the early half of the work week, a broad trough over the eastern half of the CONUS will help keep moisture in place over the forecast area and disturbances within the flow will produce daily thunderstorm chances during the afternoon and evening hours. These storms are likely to be the typical summertime pulse variety with frequent lightning and gusty winds being the primary hazard. Despite abundant surface instability peaking during the afternoon hours, shear is lacking and ultimately reducing any appreciable risk of widespread severe weather. Another hazard in any strong storms through the week will be periods of heavy rainfall as PWATs are forecast to range from 2.0-2.5" through much of the long term. While QPF through Saturday morning ranges generally from 2.0-3.0+", locally higher amounts will be possible in strong thunderstorms. As Beryl moves inland well to our west, there remains considerable uncertainty over the trajectory that Beryl`s remnants will ultimately take as it gets absorbed by the trough. It appears that enhanced moisture is likely for us midweek, but will continue to monitor the evolution of this forecast in future cycles. Monday will be the most active day for showers and thunderstorms with numerous to widespread showers and thunderstorms. This will help moderate temps in the upper 80s to low 90s, but temperatures rebound quickly and will continue warming through the end of the period to the mid 90s. Heat index values are currently forecast to reach the triple digits for many locations through the week but appear to remain sub Heat Advisory criteria, thanks to the increased cloud cover and rain chances. KAB && .AVIATION... (06Z TAFS) Issued at 200 AM EDT Sun Jul 7 2024 Variable height cigs are in and around TAF sites after another afternoon of convective storms. Expectation is that patchy low IFR/LIFR cigs will develop during morning hours and impact most TAf sites from 09/10Z-13/14Z. Some patchy MVFR vsby issues may be possible as well. Low cigs should clear shortly after sunrise. PM TSRA will be possible. Winds will be generally light and from the east to SE, 3-7 kts. //ATL Confidence...06Z Update... Medium-high morning cigs/vsby, high all others. Lusk && .PRELIMINARY POINT TEMPS/POPS... Athens 73 89 73 93 / 50 70 30 60 Atlanta 74 91 75 92 / 40 70 30 60 Blairsville 69 85 69 88 / 40 80 30 70 Cartersville 73 93 72 93 / 30 70 30 70 Columbus 76 93 75 93 / 40 70 30 70 Gainesville 74 88 74 91 / 40 70 30 60 Macon 74 91 74 92 / 40 70 20 60 Rome 74 95 74 94 / 30 60 20 70 Peachtree City 73 91 73 92 / 40 70 30 60 Vidalia 75 91 75 91 / 40 70 30 80 && .FFC WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...SNELSON LONG TERM....KAB AVIATION...Lusk