Area Forecast Discussion
Issued by NWS Atlanta, GA
Issued by NWS Atlanta, GA
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687 FXUS62 KFFC 031913 AFDFFC Area Forecast Discussion National Weather Service Peachtree City GA 313 PM EDT Wed Jul 3 2024 ...Afternoon Area Forecast Discussion... .SHORT TERM... (This evening through Thursday) Issued at 312 PM EDT Wed Jul 3 2024 An upper level ridge continues to extend from the north-central Gulf of Mexico northeastward along the Atlantic coast. As associated surface high pressure moves away to the northeast, the wedge pattern over north Georgia continues to weaken. As temperatures warm and lingering cloud cover begins to scatter out, showers and thunderstorms have begun to develop roughly south of I-20. PoPs this afternoon are forecast to be highest across west-central Georgia, where dewpoints are in the mid 70s and low-level moisture is most ample. A gradual warming trend is also ongoing under the influence of the aforementioned ridge. Aside from highs in the 80s in the higher elevations of far northeast Georgia, highs are forecast to be in the low to mid 90s this afternoon. MUCAPE values through the remainder of the afternoon are forecast to range from 1000-1500 J/kg roughly south of I-20. These instability values will be sufficient for continued convection. With vertical profiles indicating tall but thin CAPE profiles and very limited shear, the threat for severe weather this afternoon are expected to remain below severe limits. With slow storm motion and precipitable water values between 1.6-2 inches, a few storms may produce locally heavy rain. Precipitation chances will diminish after sunset. For the 4th of July, low temperatures are forecast to start the morning mainly in the mid 70s. Overnight and into the morning, continued southerly flow will bring in more Gulf moisture, and low level moisture and dewpoints in the mid 70s will continue to spread northward. Furthermore, the warming trend will continue, with temperatures rising into the mid to upper 90s across much of the area. The combination of hot temperatures and abundant moisture will allow for heat index values to reach critical thresholds of 105 degrees in many locations. A Heat Advisory remains in effect for the forecast across north and central Georgia from 1 PM until 7 PM tomorrow, with the exception of far northeast Georgia where heat indices will be well outside of criteria. Diurnally-driven thunderstorms are expected once again on Thursday afternoon. Highest PoPs are forecast across the southwest portion of the forecast area and the lowest PoPs are forecast in the far eastern portion of the area where a strong cap could potentially inhibit widespread convective development. While an organized threat for severe thunderstorms is not expected, a few storms could become strong and produce locally heavy rain and frequent lightning. Considering high precipitable water values, water loading in downdrafts of stronger storms could also produce gusty winds. King && .LONG TERM... (Friday morning through next Tuesday) Issued at 312 PM EDT Wed Jul 3 2024 Key Messages: - Hot and humid conditions will keep portions of northern and central Georgia Georgia on the cusp of Heat Advisory thresholds through the weekend. - Afternoon and evening thunderstorms should become more numerous Friday, Saturday and Sunday. An Outlook for the Weekend: Hot and humid conditions will remain the primary weather concern this weekend. Weak upper level ridging stretching from the Gulf coast to the Carolinas and rising 850 mb temperatures (to ~21 C) should contribute to gradual increases in ambient surface temperatures (mid and upper 90s). However the real kicker for the heat should be rising surface dewpoints driven by moisture advection ahead of a weak cold front. Widespread dewpoints in the lower 70s are anticipated in the state on Friday. Over the weekend dewpoints should become more bifurcated (spit by the front) with upper 60s and lower 70s in northwest Georgia and mid 70s in east central Georgia. The elevated surface dewpoints should produce oppressive humidity and push heat indices into the triple digits south of the front. Widespread heat index values of 102 to 108 degrees are anticipated on Friday. Then on Saturday and Sunday the highest values (105 to 110 degrees) should become more focused over central and eastern Georgia. A Heat Advisory may be needed for portions of northern or central Georgia on Friday (30% chance). Then over the weekend a Heat Advisory is likely (60% chance) for portions of central Georgia. The forecast position of the frontal boundary (near Interstate 85) suggest a low probability (20%) of a Heat Advisory for the Atlanta Metro over the weekend. An important caveat to keep in mind for the heat forecast is that in lingering cloud cover from convection could hold temperatures down and reduce the need for any Heat Advisories. The second portion of the forecast to monitor over the weekend will be the rising thunderstorms chances. Severe thunderstorms are unlikely due to limited shear and modest 700-500 mb lapse rates (~5.5 C/km) along and ahead of the front. That said, surface hinder the temperature forecast convergence along the front and decreasing mid level subsidence should support more widespread diurnally driven thunderstorm activity Friday, Saturday and Sunday. More isolated activity may occur during the overnight hours each day. Elevated PW values, near or above 2 inches (90th percentile for early July), should support rain rates of 1 to 3 inches per hour with the strongest convection. This could produce some isolated flooding concerns, especially Saturday afternoon and evening. Considerations of Early Next Week: Guidance from the EPS and GEFS suggests a broad area of troughing from the Great Lakes to the Central Plains early next week. With weak ridging favored over the Western Atlantic, this should lead to weak flow aloft and minimal subsidence over Georgia. Though the higher PW airmass that moved in over the weekend may moderate some on Monday, moisture and humidity should generally linger in the region. The combination of these two factors should allow scattered afternoon and evening thunderstorm activity to linger in the region early next week. Temperatures in the region should remain relatively unchanged, with widespread highs in the low to mid 90s continuing to push heat index values into the 98 to 105 degree range. Albright && .AVIATION... (18Z TAFS) Issued at 130 PM EDT Wed Jul 3 2024 Isolated SHRA/TSRA has begun to develop to the south of I-20, and is expected to increase in cover through the mid-afternoon. Ceilings have lifted to VFR, between 030-050, across the majority of the area. Ceilings will continue to lift and scatter into tonight. IFR ceilings and patchy fog will be possible in central Georgia and MCN/CSG during the early morning hours, between 10-14Z. Winds will be primarily SE at 4-8 kts through much of the period, shifting to SW on Thursday morning. //ATL Confidence...18Z Update... Medium confidence on timing of the wind shift. High confidence on all other elements. King && .PRELIMINARY POINT TEMPS/POPS... Athens 73 97 75 96 / 10 20 10 50 Atlanta 75 93 77 94 / 10 40 20 60 Blairsville 68 90 71 88 / 10 30 30 80 Cartersville 73 95 74 94 / 10 40 30 80 Columbus 76 94 77 95 / 30 60 40 60 Gainesville 73 95 76 94 / 10 20 10 60 Macon 74 95 75 95 / 30 30 20 50 Rome 75 96 76 95 / 10 40 20 80 Peachtree City 73 94 74 94 / 20 40 20 60 Vidalia 74 94 74 96 / 30 30 20 40 && .FFC WATCHES/WARNINGS/ADVISORIES... Heat Advisory from 1 PM to 7 PM EDT Thursday for GAZ001>005-011- 012-019>021-024-025-027-030>039-041>062-066>076-078>086-089>098- 102>113. && $$ SHORT TERM...King LONG TERM....Albright AVIATION...King