Weather Blog

New forecasts indicate it'll still be a dry autumn and winter

By Published: Oct 18, 2012 at 11:36 AM PDT
New forecasts indicate it'll still be a dry autumn and winter

Big fans of the August and September (and part of October) dry streak? Eager for what would pass as an encore in winter?

According to long range models issued Thursday, your wish just might be granted. (Just don't go smiling at any skiers.)

NOAA's Climate Prediction Center issued its new 30 day and 90 day forecasts Thursday. And while it still remains a bit of a mystery whether this will be an El Nino winter or not, several signs point to a dry autumn and winter, regardless.

In the short term, the maps indicate the Pacific Northwest will have a cooler than normal November, but also end up drier than normal.


(Maps legend: Temperature -- Blue=Cooler; Brown=Warmer. Rainfall: Green=Wetter; Brown=Drier)

Expanding out to the new three month forecast for November to January, it doesn't pick up much of a temperature signal -- that is new in this most recent forecast; earlier forecasts had a decent warmer-than-normal signal -- but do still solidly paint our region with drier than normal conditions.

Here is November to January map:



But what is amazing as each subsequent map: December to February, January to March, February to April, really don't show much change. It's still dry, dry, and more dry:

In fact, drier than normal weather is expected to hold through next spring.

El Nino: To be, or not to be?

Some of the changes in the forecasts are likely due to new uncertainty over what exactly the tropical Pacific Ocean is up to this winter. Models in the summer were getting pretty confident that decent El Nino conditions were on the way, and these 30- and 90-day forecasts practically wrote themselves: Dry and warm across the Northwest and North, wet and cool across the south.

In fact, here was the January-March forecast from just two months ago:



But a funny thing happened on the way to El Nino: its engine sputtered. Ocean water warmed to just under the criteria to classify it as an El Nino, but then the warming kind of stopped and some areas of the ocean are actually losing some of its earlier warmth.

As a result the atmosphere has become a bit confused, with some signs of El Nino effects burgeoning in parts of the Pacific, but not in others. Thus, it's making quite the headache for those who put these long range forecasts together:

"This is one of the most challenging outlooks we’ve produced in recent years because El Niño decided not to show up as expected," said Mike Halpert, deputy director of NOAA's Climate Prediction Center. "In fact, it stalled out last month, leaving neutral conditions in place in the tropical Pacific."

You'll notice that California, which usually gets hammered with heavy rains in an El Nino year, and thus is typically painted on these long range forecasts with well above normal rainfall, has instead now been only given the neutral "equal chance" rating for rainfall, meaning there is no weighting either way.

Here is the new map to compare to the one from two months ago:



Forecasters think there is enough momentum in the warming that we will reach the minimum standards to call it an El Nino by the end of the year. But some models now aren't so sure.

This model, which is fairly new and has the latest technology in climate modeling -- and did very well in predicting the Double-Dip La Nina last winter -- indicates the waters will instead cool a bit and we will be in a solid neutral year, especially after the new year.



What's the difference? Neutral years tend to run the gamut, and some of our strongest storms -- be it flooding, wind storms or snow storms -- have come in neutral years. (While La Nina's tend to make for snowier winters overall, neutral winters tend to have more of the major events, it just might be the only snow event of the season.) The trade off is that neutral years have also been marked with long, dry, calm stretches too.

Although the long range forecasters still say that with the El Nino/neutral uncertainty, even though their confidence in typical El Nino conditions across many regions of the U.S. is no longer high, several models do indicate the Pacific Northwest will remain drier than normal.