"KU Snowstorm" Increasingly Likely

[donsutherland1]

The extreme negative NAO has now been weakening for the second consecutive day and the GFS ensembles expect that trend to accelerate in coming days. This raises anew the point made about extreme blocks and "Kocin-Uccellini" snowstorms.

On February 23, in the post concerning extreme blocks, I noted: Considering that February 2005 is all but certain to see the SOI average -10.00 or below and Winter 2004-05 was a weak El Niño winter (not a La Niña one), should the NAO drop to -5.500 or below in coming days, the probability of a Kocin-Uccellini snowstorm at some point as the extreme blocking episode begins to weaken could be high.

The latest model guidance has continued to consolidate toward a coastal/offshore track consistent with past experience concerning extreme blocks. As noted previously, it was always the extreme block and not the smaller-scale 500 mb low that was to define this pattern. In my view, things have come together sufficiently that I believe the likelihood of a "Kocin-Uccellini" snowstorm is growing increasingly likely. This is not yet assured.

The possibility exists that Washington, DC to Boston could all see 8" or more snow. Already, I believe that DCA, PHL, and NYC will see predominantly snow (67% or more of the precipitation will fall in the form of snow). After this evening's runs, I'll offer some estimates. But from this vantage point, it is more likely that the major cities see 10" or more snow than they see less than 2"/mainly rain.

Will this storm prove to be yet another example where a good look at the past proves invaluable yet again? Stay tuned.

[Fodie77]

What are your feelings on totals for the Shenandoah Valley and northern VA?

[donsutherland1]

Fodie77,

Right now, I still believe a significant snowfall is possible for that part of the State. Certainly, it appears that the developing storm may be more moist than depicted on the models for this stage of its development. Ratios should be a little higher.

By this evening, I'll have a firmer idea as to amounts and will post those thoughts.

[Fodie77]

Fodie77,

Right now, I still believe a significant snowfall is possible for that part of the State. Certainly, it appears that the developing storm may be more moist than depicted on the models for this stage of its development. Ratios should be a little higher.

By this evening, I'll have a firmer idea as to amounts and will post those thoughts.

O.K. Thank you for the response.

[RestonVA]

newbie question. what is a Kocin-Uccellini snowstorm? I looked around on the internet and I found a bunch of stuff about storms that were considered KU's, but I wasn't able to find out exactly what it means or what criteria a storm must have to be considered one. Thank you.

[Jrodd312]

newbie question. what is a Kocin-Uccellini snowstorm? I looked around on the internet and I found a bunch of stuff about storms that were considered KU's, but I wasn't able to find out exactly what it means or what criteria a storm must have to be considered one. Thank you.

Its Paul Kocin (From TWC) snowstorm scale. Nuisence, Minor, Significent, Major or Crippling. (Not so sure on the first two but positive on the last three)

-John

[RestonVA]

from the way the word is being used, it seems to me that a Kocin-Uccellini storm is an actual type of storm that is huge, not a scale. are you sure about that?

[Coredesat]

The possibility exists that Washington, DC to Boston could all see 8" or more snow. Already, I believe that DCA, PHL, and NYC will see predominantly snow (67% or more of the precipitation will fall in the form of snow). After this evening's runs, I'll offer some estimates. But from this vantage point, it is more likely that the major cities see 10" or more snow than they see less than 2"/mainly rain.

Sorry to ask yet another question about this, but what are your feelings about the Richmond area?

[donsutherland1]

RestonVA,

I'm talking about the kind of storm that scores 3 or higher on the NESIS Scale and is among those that appear in Kocin-Uccellini's Northeast Snowstorms. Some examples of such storms include Feburary 1958, December 1960, January 1964, January 1978 (not the Midwest "bomb"), January 1987, and February 1994.

[donsutherland1]

Team Ragnarok,

Richmond is a very difficult call at this time. Significant snows could miss, but they could be very close by. I'll need to see at least the 18z data to try to pin down this area. I wish I could be more definitive or hopeful at this time, but this is an extremely difficult call right now.

[JBG]

I think RIC was in on the latest storm. Query, did it meet KU standards?