Weather Watcher: El Niño, Heavy Rain, Forecast

• Forecast
• El Niño
• Heavy Rain Storm
• September data

Forecast: A cold front is expected to move through on Monday bringing showers, a steady round of rain, and more showers to last through Tuesday evening. Wednesday looks like our dry day with the threat of showers returning at the end of the week and through next weekend. Highs will range in the low 60's until Thursday, then in the upper 50's Friday through the weekend. Lows are probably going to stick to either side of the 50 degree mark.

El Niño: As predicted, a strong El Niño has developed in the tropical Pacific ocean. This is one of the stronger ones we've had, not the strongest yet. The typical seasonal impacts that usually happen around here with this type of event is a trend of slightly drier, and slightly warmer than normal winters. I don't think it's going to be as warm as last winter was, but perhaps a little drier, with a little more mountain snow pack than last year.

Past strong El Niño's have been actually not following the normal blanket pattern of dry and mild like many forecasters and news reporters are indicating. Some strong events actually resulted in a large snow event, especially years of which involves the fading blob of warm water that was off the west coast.

In general for us, I think this means expect a normal, stormy winter with some dry periods. I think 1-2 snow events are likely, the first shot of wet snow might actually happen near mid-late November. Typically on these strong El Niño years the heavy events occurred in late January going into February.

Similar years to this winter season would be close to 1958-1959, 1965 - 1966 and 1968-1969.  There wasn't any recorded snow that I could find in records for the winter of 1958-1959, but both 1965-66 and 1968-1969 had major snow events well above 12" for the season, additionally both seasons had more than one snow event.

Heavy Rain Storm: Saturday October 10, 2015 we had our second strongest storm of the now fall season, the first storm being of course the August 29 windstorm. October 10 brought a storm that started as tropical storm Oho. The storm had since converted to an extratropical cyclone once it reached the colder waters of the Pacific Northwest. The center actually moved in just north of Vancouver Island but the rain bands still got us inside and out. Total rainfall for the day was 0.99 inches of rain, the vast majority of that rain fell between 10am and 11am. The large amount of rain overwhelmed many streams and drainage systems in the area. Winds also gusted to around 32mph that day.

Overwhelmed drainage ditch in Lake Forest Park.
Photo by Carl Dinse

September data: Believe it or not, after a long stretch of warmer than normal temperatures, September actually came in cooler than normal with a fairly normal amount of rainfall for the month. Below are some graphs of the month of September. Average temperature for September was 58.3°F, compared to the station historic average for the month, 61.6°F. Graphs below are daily average temperature for September compared to station average, followed by daily rainfall and daily maximum wind gusts.

Graph by Carl Dinse

Graph by Carl Dinse

Graph by Carl Dinse

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