NOAA Forecasts An El Nino Climate By Second Half of November – But Will it Happen?

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Discussion: Natural gas prices rose yesterday in-part due to colder weather focused on the 6-10 day period. Central U.S. (Minnesota to Texas) chill in October and a revised cooler November forecast earlier this past week is a bit of a surprise given expectations of an evolving El Nino.

El Nino is developing but El Nino 2018-19, at least initially looks different from conventional El Nino’s. What’s the difference? Look at the current SSTA pattern across the tropical/subtropical Pacific (Fig. 1) versus what a developing El Nino should like – let’s sat early November 2015 (Fig. 2). The differences are having a MAJOR impact on sensible (i.e. occurring) climate which is in-the-face of conventional El Nino climate.

The primary climate issue occurring now and related to the surprising colder Central U.S. October verification and November forecast is the above normal snow cover over south-central to southeast Canada (Fig. 3). Cold air masses are located very close to the Canada/U.S. border and more easily delivered to the U.S. with limited moderation (despite early cold season). The snow cover is present due to persistence of the polar vortex in northeast Canada in most of 2018 (Fig. 4) and the west-biased warming of the Pacific is allowing this pattern to persist in-the-face of what should be a milder El Nino climate.

Here’s the dilemma…look at the hour 360 temperature anomaly forecast by the GFS and ECM ensembles (Fig. 5-6) keeping persistence in mind and now the NOAA/CPC 16-30 day temperature probability forecast issued late yesterday (Fig. 7). See the difference? NOAA/CPC expects El Nino warming while operational models respect what’s been going on…lack of warmth due to snow cover.

So what’s the answer? First, the NOAA/CPC warming is based largely on classic November El Nino warming and in general climate forecasts made by NOAA/CPC are largely influenced by ENSO impacts simply because they’re more well-known while other climate influences identified in this report can be more profound but are less reliably forecast. The operational models clearly disagree with the warming trend – at least for just-after mid-November.

Second, what’s needed to push persistence (eastern Canada polar vortex) off the map and allow the warming to generate? Two climate events are necessary…the Madden Julian oscillation needs to emerge with intensity in the East Pacific and that event needs to push the warm water into the far eastern Pacific (and generate tropical convection). Are these requirements in the forecast?

No! The 30-day MJO forecast indicates eastward progression toward the West Pacific fades in 2 weeks and MJO weakens completely week 3/week 4 ahead (Fig. 8). Can this forecast change? Certainly! But, for now there is no justification for the NOAA/CPC warming affecting much of North America in the 16-30 day period. Forecasts for that period appear operationally beginning early next week and Climate Impact Company favors the colder persistence but identifies what’s needed to drive a super warm surge. What’s needed…MJO across the Pacific is no there yet.

While persistence hangs tough Canadian snow cover and cold bias on North America climate will continue. The warming certainly occurs at times but what’s interesting, and also in-the-face of an El Nino climate the Canadian chill related to the polar vortex may force Pacific warming farther south and into the southern U.S. where a cool winter 2018-19 El Nino climate is expected.

The bottom line? A simple warm El Nino climate mindset is a mistake based on what we’re seeing in the climate system and what can be reliably forecast well into November.

Fig. 1: Global SSTA analysis for Nov. 1, 2018 identifies the anomalous warm Pacific with a bias more toward the Dateline vs. west coast of America.

Fig. 2: Global SSTA analysis of the last El Nino episode occurring 2015-16 and the daily analysis for Nov. 1, 2015. Note the farther east SSTA warming.

Fig. 3-4: The snow cover anomalies across the northern Hemisphere for Nov. 3, 2018 provided by Rutgers Snow Laboratory (left) and 500 MB anomaly analysis for the past 6 months identifying a persistent northeast Canada/Greenland polar vortex (right).

Fig. 5-6: The 360-hour North America temperature anomaly forecasts by the GFS and ECM ensembles valid 00Z Nov. 18, 2018

Fig. 7: The NOAA/CPC day 16-30 probabilistic temperature outlook for North America valid Nov. 17-30, 2018.

Fig. 8: The ECMWF 30-day MJO forecast indicates an eastward progression through the Indian Ocean the next 1-2 weeks but intensity across the Pacific to push warm water into the far East Pacific is not there.