Mountain Weather Masters
For August 2017, the expected late-day showers and storms seemed to favor the Colorado mountains and onto the Front Range. The far West Slope and Utah saw less of the monsoonal moisture. Of the 12 sites I monitor (these sites plus Denver and Salt Lake City), only Montrose and Denver received above average rainfall. Temperatures generally were below normal across the south (at Durango, Cortez, Montrose, and Denver) and above normal central and north. Utah sites were very warm. This has produced some developing short-term drought conditions across NW Colorado. High pressure built over the Great Basin for the last days of August. The resulting NW flow cut off the monsoonal moisture and produced a strong drying and warming trend at the end the month.
The Great Basin ridge has continued into early September. It will dive down the Front Range this Monday night bringing less-hot temperatures east of the Continental Divide. For the West Slope the main effect will be more Montana smoke being pushed into the area. By Thursday the upper ridge will be pushed to the southeast as a trough works onto the West Coast. This will bring back some daily storms starting Friday. The current 8-14 day outlook (for 11-17 September) shows increased chances of wet returning to the Great Basin and Colorado, with drier than normal expected in the plains states under the ridge.
In the latest outlook from the CPC, you can see this pattern continues with wetter-than-normal odds for Colorado and the Great Basin. The autumn season of Sep-Oct-Nov shows less precipitation skill with EC or Equal Chances there. In the temperature outlook, you can see little skill for Colorado in September. The climate change signal has the entire country warmer than normal for the fall season favoring the Desert SW and Alaska.
Conditions in the Pacific have shown little change through the summer. The Nino 3.4 region along the equator is near normal. The best forecast is for ENSO to hover on the warm side of Neutral or perhaps a weak El Nino through the fall and into early winter. Further north in the Pacific, the northern basin also returned to near normal.
ENSO Neutral conditions take away all of our already meager outlook skill. So not only do we not know what is going to happen, we really don’t know what’s going to happen this fall and early winter. It is a blank slate!
Now going way out into the fall of 2018, the CPC continues to show a strong warm signal for the next 12 months especially over the Desert SW. The long-range precipitation outlook as usual shows lots of EC (Equal Chances) or low forecast skill.
Enjoy the dry next few days and the return of showers late this week.
All the Best,