Area Forecast Discussion
Issued by NWS Atlanta, GA
Issued by NWS Atlanta, GA
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
969 FXUS62 KFFC 151042 AFDFFC Area Forecast Discussion National Weather Service Peachtree City GA 642 AM EDT Wed May 15 2024 ...New 12Z Aviation Discussion... .SHORT TERM... (Today through Thursday) Issued at 339 AM EDT Wed May 15 2024 Key Messages: - Scattered showers and isolated thunderstorms are expected this afternoon. - A warming trend will arrive Thursday as high temperatures return to the mid and upper 80s. Today through Thursday: The driving forces behind today`s weather will be an upper level trough and surface low over the southern Appalachians. Westerly flow around both features will bring westerly winds to the region today. Gusts in the 20 to 25 mph range can be expected between noon and 6 PM today. Once the winds and diurnal heating kick in this morning, the ongoing low clouds and patchy fog should dissipate. By this afternoon diurnal heating should be sufficient to produce MLCAPE values between 400 and 800 J/kg. This instability should help widely scattered showers and isolated thunderstorms develop between noon and 8 PM today. Given the modest instability and weak shear (~20 kt), severe weather isn`t expected. The best thunderstorms chances should be over northern Georgia this afternoon where 700-500 mb lapse rates will be highest (near 5.5 C/km). Smaller lapse rates and narrow mid level CAPE profiles should make thunder harder to come by in central Georgia. Any rainfall today is expected to be light, brief and spotty in nature. Cloud cover should inhibit temperatures today, especially in northern Georgia where highs in the 70s are expected. More sunshine and a greater distance from the trough should allow highs to reach the mid 80s from Macon southward. Any lingering rain showers will dissipate quickly tonight with the loss of diurnal heating. By Thursday, the upper level trough that has been with us for a couple days will be replaced by a transient upper level ridge. Subsidence from the ridge should bring fair skies and dry weather to the region on Thursday. Temperatures should respond accordingly by rising to 3 to 6 degrees above seasonal averages. Expect afternoon highs in the upper 80s. Albright && .LONG TERM... (Thursday night through Tuesday) Issued at 339 AM EDT Wed May 15 2024 Beginning of the long term forecast sees our next weather system moving into the area. By Friday morning, several of the 00Z convective allowing guidance show a reasonable scenario, in which moisture is being lifted isentropically across the area ahead of the upper level low moving out of the southern Great Plains. This will likely be relatively light to moderate rain, though can`t rule out some elevated convective elements. Going forward, have chosen to "cap" our PoPs a bit here in the CWA Friday night and Saturday, as beginning to think we may see similar evolution convectively to the weather system moving through the area now. Most models, including ensembles, show a pretty sharp theta-e gradient down towards the coast, and the development of the surface low in tangent with the moving upper level low isn`t anything too special. This keeps the surface mass response modest and the theta-e gradient further south. This would likely be reinforced by any rain/T-storm development along and north of the gradient with rain-cooled air. Some of the deterministic guidance shows the potential for MCS development upstream that would likely stay along said theta-e gradient, which would keep the heaviest rainfall and thunderstorms out of the CWA (though some rain is likely to still occur). That all said, if that doesn`t play out, there is certainly the potential to see some decent rainfall out of the system as plenty of moisture returns, with the higher probabilities towards central GA which would have the best chance of seeing an organized convective system. QPF amounts are in the 1-3" range at this time, but understand that the overall potential spread is high dependent on how convection plays out...and this forecaster will fully admit to not being good enough to tell you those details 48-72 hours out. The system looks to finally lumber its way out by Sunday. Some precip chances linger as the upper level trough still could form a surface low off the coast, but guidance has shifted that a bit to be less impactful to our CWA. We should get a few days of clearing thanks to shortwave ridging that builds into the area. Moisture begins to return by Tuesday thanks to upper level system to the north, and PoP chances will slowly increase as diurnal thunderstorms become possibly (summer is almost upon us). Our next system may be impacting us by mid next week, but that is well out into the realm of uncertainty. Temperatures on days without rainfall should be pretty seasonable, generally within 5 degrees of climatology. Lusk && .AVIATION... (12Z TAFS) Issued at 636 AM EDT Wed May 15 2024 Patchy fog and areas of LIFR/IFR/MVFR conditions (ceilings 200 to 2500 ft AGL and visibilities of 1 to 6 SM) will continue through 14Z today, then the region should transition to prevailing MVFR/VFR conditions (SCT-BKN 2500 to 4500 ft AGL). West winds will set in by 15Z, and gusts of 20 to 25 kt are expected between 16Z today and 00Z Thursday. Scattered showers and isolated thunderstorms are expected between 16Z today and 02Z Thursday. Confidence in storms at the TAF sites is low. //ATL Confidence...12Z Update... Overall confidence in the trends of the ATL TAF is high. High confidence in the wind forecast. Moderate confidence in the ceiling and visibility forecast. Low confidence in the potential for storms from 17Z today to 00Z Thursday. Albright && .PRELIMINARY POINT TEMPS/POPS... Athens 61 86 62 81 / 10 0 0 50 Atlanta 61 86 65 81 / 0 0 10 60 Blairsville 57 79 57 75 / 20 0 0 70 Cartersville 58 84 61 80 / 10 0 10 60 Columbus 62 88 66 83 / 0 0 10 60 Gainesville 61 85 63 78 / 10 0 0 60 Macon 62 87 65 84 / 10 0 0 40 Rome 58 85 62 80 / 10 0 10 70 Peachtree City 60 86 63 81 / 0 0 10 60 Vidalia 66 88 67 87 / 10 0 0 30 && .FFC WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Albright LONG TERM....Lusk AVIATION...Albright