I decided to find out what we could expect this fall, winter and next spring from El Nino. Not to forecast, but rather, to get an idea of past events s, as a forecaster, I can keep my eyes peeled for certain things, and not be surprised by others.
WDAM-TV 7-News, Weather, Sports-Hattiesburg, MS
Looking back through statistics and weather data I found a bunch of commonalities between El Nino events.
Things I dun seen lots of
Missing data. Jokes (and bad grammar) aside, there was still enough to come up with a decent sample size worthy of analysis. Here are some thigns I noticed…
- October was often pretty dry. Generally during moderate, strong or very strong El Nino events, south Mississippi picked up about 50% of normal rainfall
- November and December were all over the map. Temperatures and precipitation varied greatly between events. The only constant was during strong or very strong El Nino events one of the months, in each event, saw more than six inches of rain.
- The February coming out of the El Nino was often wet – between two and four inches (sometimes more) above average.
Averages from big El Nino events
Looking at the three “Strong” or “Very Strong” El Nino events that match the closests with the current El Nino. This is data from the 1957-1958, 1982-1983, and 1997-1998 El Nino events. From that data, here are the averages for highs, lows, and rainfall…
| Months | AVG HI | AVG LO | PRECIP |
| Aug | 91.33 | 70.67 | 3.63 |
| Sept | 87.67 | 65.67 | 3.15 |
| Oct | 78.33 | 53.33 | 2.58 |
| Nov | 68.67 | 45.67 | 6.43 |
| Dec | 64.33 | 41.67 | 5.66 |
| Jan | 58.00 | 36.33 | 7.89 |
| Feb | 60.00 | 37.33 | 7.58 |
| Mar | 67.67 | 44.33 | 7.06 |
For comparison, here is the monthly averages for all years
| Months | AVG HI | AVG LO | PRECIP |
| Aug | 92.2 | 70.8 | 4.73 |
| Sept | 87.7 | 65.9 | 4.08 |
| Oct | 79.5 | 54.5 | 3.75 |
| Nov | 70 | 45 | 4.27 |
| Dec | 61.8 | 39.6 | 4.91 |
| Jan | 59.9 | 37.3 | 5.74 |
| Feb | 63.4 | 40.2 | 5.39 |
| Mar | 71.3 | 46.8 | 5.5 |
Great, Nick! But what does this tell us?
Ultimately, not much. Each year is different and this El Nino is very different. In the numbers I was looking at, though, it seems like this El Nino matches up best with the 1957-1958 El Nino is a few different places.
- Both El Nino events started brewing in early Spring.
- The 1957-1958 El Nino started after 36, 3-month running mean of ERSST.v4 SST anomalies of neutral of below average temperature readings in the Pacific at Niño 3.4 region (5N-5S, 120-170W). Thirty-eight if you count at or below a .5 reading. This 2015 El Nino is coming off 52, 3-month running mean anomalies.
- The MAM – MJJ ramp up was similar. in 1957 it was .6 -> .7 -> .9. In 2015 it was .7 -> .9 -> 1.
Does that mean this fall, winter and next spring will be like 1957-1958? Doubtful. But we may be able to find some similarities. And it is a good place to start. Most climatologists and El Nino experts are comparing this El Nino to the 1997-1998 El Nino based on it’s potential strength. I’m not going to argue with their expertise. Locally, though, I will try to keep my eye on trends.
If you’re curious how the 1957-1958 fall winter and spring looked like, well, I have good news, here is a look at that data…
| AVG HI | AVG LOW | PRECIP | |
| Aug | 93 | 70 | 2.53 |
| Sept | 84 | 67 | 14.81* |
| Oct | 75 | 52 | 2.69 |
| Nov | 70 | 49 | 7.8 |
| Dec | 66 | 40 | 3.13 |
| Jan | 56 | 33 | 4 |
| Feb | 56 | 32 | 7.16 |
| Mar | 66 | 44 | 7.83 |
* Two tropical systems brought more than seven inches of rain t the area
In the end…
Prepare for the upcoming fall, winter and next spring like you always would. Seasonal forecasts are very difficult. There isn’t come magical formula, there isn’t a special book, and anyone who tells you they know how things will shake out for sure is lying.
Data shows that past events were one way, but the great thing about weather is that it is always changing. No two days are ever truly alike.
