GaWx

Agree 100%! A 4-6” late Feb storm in La Niña at RDU would be a rarity. RDU La Niña 4”+ snows Feb 15-28: 2/16/1996: 5.6” 2/23-4/1989: 4.2” 2/17-8/1989: 4.9” 2/25/1894: 5.0” GSO had 5.7” just after Feb (3/1-2/2009).

0Z GFS:

Plus it has a 1060 mb high.

The week 2/19-25 has a good chance to end up the coldest week of the winter at GSO (and at other NC cities). If so, it would be the latest coldest week there since way back in 1993! Then the coldest was 3/13-19/1993 due to the superstorm. Going back to 1959-60, the only two other winters with a later coldest week were 2/21-27/1967 and 3/4-10/1960.

The new Euro Weeklies for 2/17-23 is the coldest yet for that week in the SE. In terms of anomalies, this would be the coldest of the winter in most of NC if it were to verify. In terms of absolutes, it would be close to Jan 20-26 for coldest in much of NC. For S GA/SC, it would be either 2nd or 3rd coldest in terms of anomalies/3rd coldest in terms of absolutes. For N GA/upstate SC, it would be ~a tie with Jan 20-26 for coldest anomaly and would be 2nd or 3rd coldest in terms of absolutes:

In addition to 2/13-14/1960, it appears that the terrible 2/2/1996 icestorm was from a Miller A. I don’t even see a wedge! https://products.climate.ncsu.edu/weather/winter/event/?e=159 At the time it was the worst ever in Hickory and Statesville for outages: “By 1500 EST, many major population centers such as Hickory and Statesville were reporting 50 percent power outages. The storm became the "worst ice storm ever" in local power company records. By late night most customers had lost power. Many customers did not have power restored for up to a week during extremely cold weather.” @StantonParkHoya

I see the 1/2” of ZR on WB Euro. However, I recently posted that the WB Euro algos for ZR vs IP appear to be off in that it has too much ZR at the expense of IP. In S Franklin Cty in case you didn’t see this, the 925s never get above -3C and the 850s never rise above +2C. That imo would mean little ZR RDU/Franklin Cty and 1.5-2” more IP than what’s on the Euro output.

GEPS (2/22-3):

This next SW is mildly interesting on the 12Z Euro as at face value it is a close call for a light wintry event here and nearby (coastal SE) with the low going across S FL in combo with lingering Arctic air to the N: EPS has a decent Miller A storm signal:

The WB Euro algos for ZR vs IP appear to me to be too tilted to ZR and too little for IP. Note that the GFS and CMC on WB both tend to have more IP than Euro. Looking at the 12Z Euro qpf/850s, it has for RDU ~10 times as much qpf as ZR vs IP. But that’s despite highest 850’s staying near +1C and warmest 925s being -3C! I believe that if the algos were corrected that nearly all of the ZR at RDU is really IP. Thus the Euro’s sleet map showing 0.2” should imo be ~2.2” of sleet to go along with the 4.1” of Kuch snow meaning 6.3” of snow/IP with almost no ZR at RDU.

12Z Euro

YW. Total UK RDU qpf 1.5”. Of this ~0.1” is snow, ~0.1” is sleet, ~1.1” is ZR (ouch), and 0.2” is rain.

Based on 850s, RDU gets ~1” of snow in the first few hours. But then it changes to a short period of sleet followed by a long period of ZR with even a short period of rain at the very end (33F).

I’m checking this link’s worst icestorms for the E Piedmont and am looking for wx maps to see: http://americanlifelinesalliance.com/pdf/IceStormSummaries.pdf Per this link, 2/13-15/1960 was worst icestorm in 33 years in much of NC. Here is a link to the 2/12-14/60 wx maps, suggesting a Miller A: https://library.oarcloud.noaa.gov/swm.docs.lib/1960/19600212.pdf https://library.oarcloud.noaa.gov/swm.docs.lib/1960/19600213.pdf https://library.oarcloud.noaa.gov/swm.docs.lib/1960/19600214.pdf Per this snow map from Webb, it also was a big snow producer for much of NC, with 3.7-5” in RDU area:

Yep. 850s are +2 or lower for 3/4 of the qpf keeping ZR much lower than GFS; total qpf ~0.95” CMC, similar to gfs but much less than 1.65” of icon

With 850s at +4 for the majority of the qpf on the 12Z GFS, mainly ZR at RDU would agree with the past….if those 850s were to verify.

12Z GFS:

From what I experienced in ATL and SAV (and confirmed by what I’ve studied), the conversion of ZR to accrual on branches/bushes approached 50% under ideal accrual conditions (winds not too strong, rain not too heavy, temps not right at 32, etc).

I think that’s conservative at this point per model consensus, which suggests at least ~twice that much accretion is quite possible. But a long ways to go.

That (12Z Icon) could mean ~0.7” of ice accretion on trees in RDU, a huge problem that would be similar to 2002. It takes only 0.5” of accretion for widespread power outages:

12Z Icon for RDU suggests ~0.1” qpf of snow, ~0.2” qpf of sleet, and ~1.35” of ZR. Temps get to as low as 27F at end of ZR.

The preliminary AO for today per CPC is -5.26, well predicted. This would compare to the alltime record -AO for Feb, -5.29 (2/5/1978).

I’ve found based on analysis of 850s for SE winter storms going back many decades that +1 to +2 850s tend to be sweet spot for sleet and +3 to +5+ tends to be sweet spot for ZR.

That’s the point. 2002 was Miller B/quite different. Miller A (upcoming storm) typically not as associated with major ice. But model consensus still shows a lot of ZR. Maybe that will change.

For comparison, here are the sfc maps for Dec of 2002 Miller B major icestorm for NC: