498 FXUS62 KFFC 131422 AFDFFC Area Forecast Discussion National Weather Service Peachtree City GA 922 AM EST Mon Dec 13 2021 .UPDATE... High pressure will continue today. No major changes needed to the current forecast. Will tweak the hourly temps/dews. .PREV DISCUSSION... /Issued 518 AM EST Mon Dec 13 2021/ ..12Z Aviation Discussion... PREV DISCUSSION... /Issued 401 AM EST Mon Dec 13 2021/ SHORT TERM /Today through Tuesday/... High pressure will dominate the forecast regime through the short term with clear skies, calm to light winds, and seasonal temperatures. Highs will be in the low-mid 60s, with morning lows generally in the low to mid 30s. Only deviations to a National Blend of Models forecast are concerns with dry air entrainment with seasonally-relative deep mixing with clear skies and free atmosphere relative humidity around 2 percent above the residual layer, which extended roughly 1 km above the surface. As a result, we've dropped dewpoints more in line with MOS guidance, especially in the higher elevations where exposure to the drier air is more easily attained. In addition winds will be very light to calm, with variable wind directions, which will only be a concern in the aviation community. With surface high pressure to the north and 850 hPa high pressure to the south wind direction will change from easterly near the ground to westerly just above the ground, so we wouldn't be too surprised to see wind directions flip- flopping around a bit this afternoon. Thiem LONG TERM /Tuesday Night through Sunday/... At the start of the long term strong H500 ridging continues across the Mid-West and Southeast with a sub-tropical high over the Gulf of Mexico and an upper level trough digging down the California Coast. Meanwhile, at the surface high pressure encompassing much of the eastern CONUS will support easterly flow and eventually, by late week, southerly flow across the CWA. Despite the initial easterly surface flow the sub-tropical high with the eventual aid of the southerly surface flow late in the week will result in high temperatures climbing well above normal through Sunday. The climax occurs Friday whens highs reach the low to mid 70s north of the Fall Line and upper 70s south of the Fall Line --- at least 15 degrees above normal. Wednesday, the aforementioned West Coast upper level trough and stacked surface low quickly skirts through Four Corners and jets NE towards the Great Lakes region dragging a cold front through the Mid- West and eventually into the SE. However, Friday as the parent upper low tracks further and further northeast into Canada the front takes on a more west to east orientation and stalls just north of the FA. The front lingers north until Sunday when a secondary upper level shortwave moving through the Great Lakes region forces the front southward in GA. PoPs increase in coverage and magnitude ahead of the front Saturday into Sunday. Sunday and Monday in the wake of the front CAA will allow high temperatures to fall closer to normal. 28 AVIATION... 12Z Update... VFR to prevail through TAF period with SKC forecast with no CIG, VSBY, or precip concerns. High pressure regime settling in over the forecast area with different high pressure centers at different levels of the atmosphere, which means winds will be light but variable at times. Winds expected to generally retain easterly component at ATL and remain at or below 5 knots but could swing to SSE to NNE at times, and occasionally go westerly fro brief periods. //ATL Confidence...12Z Update... Low-Medium on WDIR. High on all other elements. Thiem && .PRELIMINARY POINT TEMPS/POPS... Athens 33 64 38 60 / 0 0 0 0 Atlanta 37 63 42 61 / 0 0 0 0 Blairsville 33 66 37 60 / 0 0 0 0 Cartersville 32 64 41 63 / 0 0 0 0 Columbus 39 67 45 68 / 0 0 0 0 Gainesville 36 64 41 59 / 0 0 0 0 Macon 35 66 42 68 / 0 0 0 0 Rome 32 65 41 66 / 0 0 0 0 Peachtree City 32 64 39 64 / 0 0 0 0 Vidalia 43 67 49 71 / 0 0 0 0 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...NListemaa LONG TERM....28 AVIATION...Thiem