40/70 Benchmark

That actually could be worse.....it crosses near the tip of LI, as is, so much of LI would be spared the catastrophic surge. Send that 50-70mi westward if you would like to wipe them.

No. @ Pit

One day it won't-

One thing worth noting is not all East-based Nina's are frigid, as there is variability due to the relatively weak ocean-atmosphere coupling. This is because many east-based events, as is the case with modoki el nino events, are weaker. You can have warmth, especially if the event is weaker, and one such case is 2005-2006. Likewise, there were some weak modoki events that were fairly cold across the eastern US, such as 2000-20001. This is further proof that there does indeed exist a structural mechanism beyond strength that dictates the overall character of la nina events and one of the focal points of this writing is to elucidate that point. There are some "hybrid" events that share both east-based and modoki traits. You can have a Nina that is a mix of east-based versus central-based, or "basin-wide", such as both this season and last.

This is what I try to address by binning the ENSO events by structure...you can't explain everything because there are so many extemporaneous factors, but it does illuminate the issue somewhat. Given that a strong la nina is not anticipated this season, here is our running composite of successive la nina events, which remains largely unchanged. However, the composite is heavily skewed by the very anomalously mild 2011-2012, as composite is much cooler if this season is subtracted. An examination of cool ENSO events by intensity confirms that the outlier of 2011-2012 heavily skews the dataset of weak to moderate successive la nina events warm. Cool Neutral: Weak La Nina: Moderate La Nina: Strong La Nina: Clearly there are significant differences with respect to the pattern across the northern hemisphere that are at least partially governed by the intensity of the cold ENSO event. Thus it is important to focus not necessarily on whether or not the la nina event is successive, or as we will come to learn not even solely on the intensity itself, but rather precisely what structural nuances are attributable to these differences in order to properly diagnose and forecast a la nina season. Indeed, the primary difference as it pertains to North America is with respect to the Aleutian Low and its interaction with the polar fields. The stark contrast between the 2011-2012 season, which peaked with a marginally moderate ONI at -1.1, and the robust la nina of 2010-2011 with a peak of -1.6 ONI demonstrates this disparity quite well. What is also clear is that intensity, while undoubtedly a contributing factor, is not the only determinant, otherwise the strong la nina season of 2010-2011 would have been much milder for the eastern US than the rather modest la nina event of the 2011-2012 season. And for those wondering, yes, the 2010-2011 la nina was the first event, and the 2011-2012 episode was the second consecutive. However, the remaining "mild second year la nina in the east" crowd should also ponder why the strong, second year la nina event of 1955-1956, which peaked with an ONI -1.7, evolved in much the same manner as the 2010-2011 event. Thus far it has been illustrated that while stronger la nina events tend to be milder for the eastern US due to a flat Aleutian ridge and dearth of high latitude blocking, there are some stronger events such as 1955-1956 and 2010-2011 that seem to have a more poleward Aleutian ridge, similar to the weaker la nina composite. Likewise, there are also more modest la nina events, such as 2011-2012, that behave similarly to the stronger ONI composite in that the Aleutian ridge is very flat and the eastern US is very mild. This tends to correlate to a very active Pacific jet that inundates most of N America, save for Alaska, with mild Pacific air masses.

The blocking is key to avoid the inevitable and inexorable eastward leak in track upon approach that is often so crucial to averting disaster at this latitude. Surprising how many forecasters miss that.

Up to that point, its similar to Bob, but the difference is that Bob was allowed to leak east beyond that....this one is blocked, so all hell breaks lose.

I am the first one to down play potential SNE tropical scenarios, but that would be scenario to assume a different posture. That ever showed up inside of 4 days or so, I'd be guns blazing...

From reality, probably.

I like what you did for individual seasons, though...I may adopt that.

Not going to lie...this just prompted me to view a model for the first time in 6 months. That run is a special kind of "oh shit", as it intensifies on approach to the latitude of Hateras, before taking a track perhaps just east of 1938 and Gloria....that would even spell trouble for MEHthuen.

The ensembles will probably have like half of the members buried over the tallest peaks of Hispaniola, and half through the goal post.

Wasn't "at" you...obviously you know this...

Only above 700' in Tolland

We have a reasonable consensus that this is a threat come this weekend, then I will blog away....attm, we ignore.

Meh, I wipe the dew mist out of my crack w hr 240 charts.

Paul I mean more for a composite, when you have a plethora of seasons from various decades...you have to choose one climo set, which is partly why I opt for the most all-encompassing set.

Eric Webb sends @Typhoon Tipan early xmas gift: The mid-troposphere temp gradient b/t the tropics & mid-latitude N Hem was at its weakest on record this summer. A weaker gradient leads to a stretched/weak Hadley Cell, favoring sluggish TC activity globally, as TCs are unable to transport heat out of the tropics as efficiently

The result will be your composite will have overall slightly lower heights, and mine higher.

Track and intensity are intertwined because TBH I would rather not see it organize much with Hispaniola being a distinct possibility. You don't want highly organized, well coupled circulation traversing that island because they become so severely disrupted that dissipation is a distinct possibility, whereas a more diffuse system is more likely to simply redevelop along either coast of the island.

I only use analogs going back to 1950....just using an 1951-2010 catch all.

In all seriousness, I don't think this season will suck.....IMBY porkies not withstanding.

This is also in accordance with central-based la nina climo.

Great tool, but that is an obnoxious bug. Which climo period are you going to be running your composites against? I can't stand using the latest ones, even though that is the protocol.....I don't feel as though it provides an accurate portrayal because 2/3 of the composite ends up smeared in blue (it looks like winter-mode Kev made them)....especially in a climate in which cold underperforms at least excuse imaginable. I would rather my visual presentations depict a canopy of higher heights.

Nope...I'm thinking 1995-1996 like Novie through January, transitioning to Feb 2015 and then March 2018..... And them I'm changing my initials to JB.