By Rod Hill on 2014-10-25
Before I begin, let me remind you that our wet weather since October 11th was not projected. In fact, October was forecast to see below normal rainfall. To date, Portland is on track to see more than 4.00" of total rainfall for the month, well above the climate average of 3.00 inches. The last two weeks have been a vivid reminder that abrupt changes in Northwest weather patterns often happen with little warning and no forecast of likelihood.
My 2014-2105 Winter Forecast hinges on the projection of a weak El Nino or Neutral Enso cycle, referring to equatorial ocean waters off the coast of South America being near or slightly warmer than normal for the season. The graphic shows the breakdown of winter precipitation since 1950 for the years in question.
Notice the nearly 50-50 percent split of dry seasons verses wet winters. Most of the years reviewed had little total snowfall. The graphic suggests little snow for this up-coming winter and no confidence in terms of below or above normal precipitation.
It is interesting that when I compared winter seasons following the top five hot summers, in terms of 90 degree days, I also found a 50-50 percent split between wet seasons and below normal rainfall years. Snow history also mirrored the weak El Nino years with most seasons seeing a few inches, but one year showing a solid 8" of snowfall! There are a handful of other parameters I gathered and calculated, but in a nut shell my best guess to prepare for this winter season is the following:
1. Temperatures: Normal To Above.
2. Precipitation: No Confidence To Predict A Wet Or Dry Winter. However deviations from climate normals will likely hold within 4 inches for the season.
3. Valley Snow: Trace To 4", one 8" event looks possible
4. Mt. Hood Snow: A Good Average Season With 500 Inches Total Snowfall..
The valley's last big wind storm occurred back in December 2006 when Salem had winds reaching 80 mph and the Portland metro had 70 mph gusts, while PDX spiked at 53 mph. The repeat cycle for winds reaching 70 mph or higher seems to be about 10-15 years, meaning Portland might go another year or two before we see another "big blow."
I am a big believer in following current weather trends. Here is what to watch for:
The past 10 years have shown a trend for as much rain during the spring as the winter months, meaning a downward trend in total rainfall for the months of November - February and an up tick for March - June. All but two of the last 11 Februarys have seen very low rain totals when compared to climate averages. Something else to watch for will be the average elevation of Mt. Hood snowfall. The freezing level makes all difference in a good verses bad ski season.
I hope you enjoyed reading my thoughts and research. In a nutshell, this winter will likely offer typical Northwest weather. Mostly mild temperatures and rainy days are expected with a possible snow event just for fun!
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MY 2014-2015 WINTER FORECAST:
1. PRECIPITATION: Little confidence to project. Look for a few inches within the climate normal.
2. VALLEY SNOWFALL: A few inches possible, the valley may see one big 8" event.
3. MT. HOOD SNOW: A good, average season, total snowfall at Timberline near 500 inches.
4. ARCTIC OUTBREAK: Good chance of one or two cold episodes.
5. WINDSTORMS: Not due for anything more than a few 40-55 mph gusty wind events.
Please send your questions and thoughts to my email: rod@rodhillforecast.com
Thank you for reading,
Meteorologist Rod Hill
Total Lunar Eclipse Wednesday morning