textproduct: Peachtree City

KEY MESSAGES

Updated at 651 AM EST Thu Dec 26 2024

- Cool temps north GA through Friday due to cold-air damming event persisting into Saturday.

- Scattered showers expected Friday NW spreading east and increasing in coverage and intensity Saturday and Sunday.

- Heavy rain and strong or even some severe storms possible on Sunday with up to 3 inches of rain possible.

- Temperatures will be much above normal through the weekend and into early next week, with colder temperatures returning by mid-week.

SHORT TERM

(Today through Friday) Issued at 343 AM EST Thu Dec 26 2024

No major forecast concerns or weather impacts expected in the short term. Cold air damming event expected as clouds and eventually precip spread over the state. Typically a day like this Friday is when we see our largest forecast temperature "busts", as models try to erode wedge air mass too quickly in the face of increasing precip rates and near surface cold/dry advection. Lowered temps and dewpoints a bit using uncalibrated global and convective allowing models with NBM.

The heavier precip and chance for convection will increase this weekend.

SNELSON

LONG TERM

(Friday night through Wednesday) Issued at 343 AM EST Thu Dec 26 2024

A weak upper ridge will be shifting off the SE U.S. Coast at the beginning of the long term period as a broad upper trough spans from the Rockies to Central Plains. A shortwave is forecast to develop in the base of this trough near the OK Panhandle by Saturday, then shift NE to the OH Valley by Sunday. Another shortwave will develop over the Central Plains on Monday, then lift NE over the Great Lakes region by the middle of next week.

At the surface, a cold front will extend from low pressure over IA to S TX Friday night. A weakening wedge will keep areas NE of the Atlanta metro area cool on Saturday. The cold front will shift rapidly E by Sunday. Instability and deep layer moisture will be increasing across the area on Saturday with widespread showers and isolated thunderstorms developing near a quasi-stationary front across N Central GA. This front will lift N late Saturday, with rainfall temporarily waning. However, this will be short-lived, as heavier rain ahead of the approaching cold front spreads into the area late Saturday night into Sunday.

Guidance continues to indicate the confluence of bulk layer shear, lingering jet dynamics, instability, and a plume of 1.5+ inch precipitable water (PWAT) ahead of the cold front during the day Sunday. This may lead to the potential for stronger and more organized thunderstorms, particularly near and S of the Atlanta metro area. Additionally, heavier rainfall is anticipated during this period. Storm total rainfall amounts are forecast to range from .5-1" across our SE zones to around 3" across the N where orographic lift is expected to enhance rainfall rates late Saturday night into Sunday. Locally higher amounts are possible, both across S facing slopes in the N and elsewhere where heavier showers or storms train over the same areas for extended periods of time. WPC continues to highlight the N half of the area in a marginal risk of excessive rainfall.

Another surface low associated with the second shortwave will move from the OH Valley to S New England by mid-week. This is forecast to bring a quick shot of additional rain to the area, but this system will be starved for moisture, and rainfall amounts are expected to remain less than a quarter of an inch and focused mainly across the N portion of the area.

Temperatures will be quite warm across the area ahead of Sunday's front, with highs mostly in the 60s to lower 70s (10 to 15 degrees above normal) and nighttime lows mostly in the 50s (20+ degrees above normal). Nighttime lows will drop about 10 degrees behind Sunday's front, with the effect on highs less significant. Return flow ahead of the next, quick-moving system will prevent a more significant cool-down. Temperatures will finally return to near normal by the middle of next week. /SEC

AVIATION

(12Z TAFS) Issued at 651 AM EST Thu Dec 26 2024

Cigs came in 2000-2500ft a bit earlier than expected and could drop to 1500-1800ft before gradually improving to 2500-3500ft this afternoon. Some very light -SHRA also likely today but coverage too low to include in fcst. Cigs will drop slowly overnight but fall more quickly to IFR by 13Z Fri and possibly LIFR by 17Z. Sfc winds will remain E 8-12kts while slowly increasing to 12-15kts with G20-23kts after 12Z Fri.

//ATL Confidence...12Z Update...

Medium confidence on MVFR/IFR cig timing. High confidence on all other elements.

SNELSON

PRELIMINARY POINT TEMPS/POPS

Athens 52 41 47 42 / 0 10 50 70 Atlanta 51 43 50 46 / 0 10 30 80 Blairsville 52 39 47 42 / 0 10 60 90 Cartersville 54 44 50 46 / 10 10 50 80 Columbus 56 46 60 54 / 10 10 10 50 Gainesville 52 41 45 41 / 0 10 50 80 Macon 53 45 56 52 / 10 10 20 40 Rome 54 43 51 47 / 10 10 60 90 Peachtree City 51 43 52 48 / 0 10 20 70 Vidalia 56 48 63 56 / 10 10 10 20

FFC WATCHES/WARNINGS/ADVISORIES

None.