The GEFS projects AO ~+2.0 and NAO ~+1.7 for 12/12-3, the time of the potential major ZR at ATL.
Out of 28 major winter storms at ATL since 1950, here are the most + AO/NAO combos:
1/9/62 1.8, 0.6: SN
1/18-9/62 2.8, 0.2: ZR
3/13/93 1.7, 0.5: SN
1/28-30/00 3.5, 0.4: ZR
3/1/09 2.3, 1.0: SN
2/12/14 1.0, 0.8: ZR
So, IF this ends up being a major at ATL, the ~+1.7 would by far be the most +NAO with the closest being +1.0 (3/1/09). The AO of ~+2.0 would be 3rd highest.
Just how high is a +1.7 NAO? Since 1950, only ~2% of days have been at +1.7+ and the last one was way back on April 22. The record high is ~+2.6.
Out of 28 major winter storms at ATL since 1950, here are the most + AO/NAO combos:
1/9/62 1.8, 0.6: SN
1/18-9/62 2.8, 0.2: ZR
3/13/93 1.7, 0.5: SN
1/28-30/00 3.5, 0.4: ZR
3/1/09 2.3, 1.0: SN
2/12/14 1.0, 0.8: ZR
So, IF this ends up being a major at ATL, the ~+1.7 would by far be the most +NAO with the closest being +1.0 (3/1/09). The AO of ~+2.0 would be 3rd highest.
Just how high is a +1.7 NAO? Since 1950, only ~2% of days have been at +1.7+ and the last one was way back on April 22. The record high is ~+2.6.