|El Niño||La Niña|
|Weak – 10||Moderate – 7||Strong – 5||Very Strong – 3||Weak – 10||Moderate – 4||Strong – 7|
Above is the table I cobbled together on the years of Niña and Niño. Climate conditions across the tropical Pacific were neutral when averaged over the month of September 2018, but trade wind anomalies and ocean warming in the eastern Pacific in late September and early October were decidedly El Niño-like. There’s a 70-75% chance of a weak El Niño during Northern Hemisphere winter 2018-19. Since the 1950s there have been 10 weak El-Niño years.
El Niño and La Niña are the warm and cool phases of a recurring climate pattern across the tropical Pacific—the El Niño-Southern Oscillation, or “ENSO” for short.
The pattern can shift back and forth irregularly every two to seven years, and each phase triggers predictable disruptions of temperature, precipitation, and winds.
These changes disrupt the large-scale air movements in the tropics, triggering a cascade of global side effects.
Though ENSO is a single climate phenomenon, it has three states, or phases, it can be in. The two opposite phases, “El Niño” and “La Niña,” require certain changes in both the ocean and the atmosphere because ENSO is a coupled climate phenomenon. “Neutral” is in the middle of the continuum.
- El Niño: A warming of the ocean surface, or above-average sea surface temperatures (SST), in the central and eastern tropical Pacific Ocean. Over Indonesia, rainfall tends to become reduced while rainfall increases over the tropical Pacific Ocean. The low-level surface winds, which normally blow from east to west along the equator (“easterly winds”), instead weaken or, in some cases, start blowing the other direction (from west to east or “westerly winds”).
- La Niña: A cooling of the ocean surface, or below-average sea surface temperatures (SST), in the central and eastern tropical Pacific Ocean. Over Indonesia, rainfall tends to increase while rainfall decreases over the central tropical Pacific Ocean. The normal easterly winds along the equator become even stronger.
- Neutral: Neither El Niño or La Niña. Often tropical Pacific SSTs are generally close to average. However, there are some instances when the ocean can look like it is in an El Niño or La Niña state, but the atmosphere is not playing along (or vice versa).
The relative strength of an El Niño event (weak, moderate, strong) can impact the effect El Niño has on weather in North America. Stronger events can have more of an effect on global climate patterns while weaker El Nino events can be overpowered by other factors. Winters during strong El Niño events were much warmer across the northern half of the country, while temperatures were closer to normal during moderate and weak El Niño winters. Combined with other climate factors in play, there can be quite a diversity of scenarios during an El Niño event.
We can have cold shots with weak El-niños with Arctic air blowing across the great lakes creating lake effect snow storms dependent on wind direction and moisture content. This could create a scenario where the lakeshore counties could see more snow than inland and the state as a whole could less lesser amounts with the exception of the lakeshore counties.
This past year has seen the whole range of weather conditions from hot and dry to cool and wet with an up and down pattern with most months warmer than normal. We now have a high pressure block over Alaska where it is warmer than normal and all the cold air has pushed south out of Canada to the east of this block bringing us cooler than normal temps.
This is not my winter forecast, I am just giving information on one of the many factors of what leads up to the forecast. In the past I have seen the winter forecasts flop, more often than not due to these other factors, such as the Arctic and North Atlantic Oscillations which I will get in to in other posts. Michigan is one of those states where lake effect figures in also. Perhaps we should drag out Punxsutawney Phil to see what he has to say – I am sure he has gone to ground and would rather be left alone.
It is 33° at 6:30 this morning with clear skies. Sunrise is around 8:00 and sunset is now 6:50. Daylight savings time ends on November 4 which will move our sunset time to 5:32pm.
Today will be a beautiful fall day with plenty of sunshine and temps will be in the low 50s. This will be the warmest day of the week. A cold front will move through tonight which will bring little or no rain – any rain we see will be from lake effect and be mainly in the northern counties.
The remnants of hurricane Willa currently in the eastern Pacific could affect our weather this coming weekend which may bring a mixed bag of winter precipitation – not engraved in stone yet – it is dependent on the track of the system.
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