Area Forecast Discussion
Issued by NWS Atlanta, GA
Issued by NWS Atlanta, GA
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376 FXUS62 KFFC 231832 AFDFFC Area Forecast Discussion National Weather Service Peachtree City GA 232 PM EDT Mon Sep 23 2024 ...New 18Z Aviation Discussion... .SHORT TERM... (Today through Tuesday) Issued at 332 AM EDT Mon Sep 23 2024 500mb analysis shows NW flow aloft with a high pressure anchored off the SE coast of TX. This high center should migrate eastward across the northern GOMEX through the period. The mid level flow across the state should go briefly zonal and then SW by early Tuesday as a longwave trough pushes into the Mid Mississippi River valley. At the surface, a weak surface trough continues across central portions of the state. A weak frontal boundary will approach from the west through the period while ridging remains across the northern GOMEX. Moisture will continue to slowly increase across the area, along with the chances for pops, especially across the northern tier of zones. The southern tier of zones will be closest to the mid level and surface ridges and pops remain lowest in this region. Pops will remain isold/sct in nature across the northern half of the CWA through the period. Severe weather is not anticipated at this time. Temps continue above normal through the period. Adjusted the MaxT values upwards a couple of degrees from the blend. ATL may approach another record high for the next two days. NListemaa && .LONG TERM... (Tuesday night through Sunday) Issued at 332 AM EDT Mon Sep 23 2024 At the upper levels, a positively-tilted trough will be positioned over the eastern CONUS at the start of the long-term period. At the surface, a weak area of low pressure over the Ohio River Valley and eastern Great Lakes region will push a weak cold front across the Tennessee River Valley, perhaps making it into north Georgia. As a result, rain chances will be greatest generally along and north of the I-85 corridor Tuesday night through Wednesday night. Both instability (CAPE and mid-level lapse rates) and wind shear from the surface to 500 mb will be marginal at best, indicating that while isolated to scattered thunderstorms are expected, widespread severe weather is unlikely. The impactful portion of the long-term period will be Thursday through Saturday. The National Hurricane Center (NHC) is indicating a high (70%) chance for tropical development over the northwestern Caribbean Sea and adjacent portions of Central America in the next 48 hours. Ultimately, a tropical depression or tropical storm is very likely (90% chance) to develop in the next few days as the system moves northward into the southeastern Gulf of Mexico. During the latter half of the week, the system is expected to track generally northward across the eastern Gulf. At 4-5 days out, it is still best to lean on ensemble guidance to get an idea of the potential evolution of the system and potential impacts on the Southeast. The GEFS moves the system northward slightly faster than does the EPS, but the tracks that both ensembles depict are very similar, with the system having a spatial extent from Florida to Louisiana. The track of this system will depend largely on how the aforementioned upper-level trough evolves over the eastern CONUS (its strength, position, southern extent) and thus how it steers the system. The degree of impacts across north and central Georgia is still relatively uncertain, but we are currently expecting most impacts to occur on Thursday and Friday. As far as impacts, periods of heavy rainfall and resulting flash flooding and/or river flooding, gusty winds, and tornadoes will be on the table should north and central Georgia be on the eastern side of the system. Forecast rainfall totals are largely unchanged from the previous forecast package, with essentially area-wide totals of 3" to 4". Localized swaths of 5" or more are possible in the event of intense and/or long-lived rainbands, but it is futile to attempt to pin down where such rainfall maxima could occur at 4-5 days out. Residual tropical moisture, along with what ensemble guidance suggests is expansive upper-level troughing, looks to keep 20% to 30% PoPs in the forecast on Saturday and Sunday. Aside from Wednesday, highs will be in the 70s and 80s thanks to increasing cloud cover and increasing coverage of showers and storms. Martin && .AVIATION... (18Z TAFS) Issued at 224 PM EDT Mon Sep 23 2024 VFR through TAF period. Expecting some afternoon cu impacts at most all sites today and tomorrow. Winds will be on the west side through period in the metro at 5-10 kts, going light overnight. In MCN/CSG, winds will be more southerly tomorrow, similar speeds. Some TSRA impacts possible at AHN until 00Z, starting around 20Z. //ATL Confidence...18Z Update... High all elements. Lusk && .PRELIMINARY POINT TEMPS/POPS... Athens 69 91 68 83 / 20 20 30 40 Atlanta 72 93 71 82 / 10 10 30 60 Blairsville 64 84 63 74 / 20 40 60 80 Cartersville 69 93 67 81 / 10 20 40 80 Columbus 73 93 72 85 / 0 0 20 60 Gainesville 69 90 68 79 / 20 20 40 60 Macon 72 93 70 87 / 10 10 0 30 Rome 69 93 67 80 / 10 20 60 90 Peachtree City 70 91 68 82 / 0 10 20 60 Vidalia 72 93 70 89 / 10 0 0 10 && .FFC WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...NListemaa LONG TERM....Martin AVIATION...Lusk