November Monthly Weather Retrospective

John McGinley, Peak to Peak. November 2017 ended up an exceptionally warm, frequently windy, and dry month. Strong westerly and northwesterly jet streams set up a pattern with low pressure troughs east of the Front Range. This, of course, creates the extreme high-to-low pressure gradients that make our winds blow. Nineteen days went 40mph or above with 4 days at or above 60mph. With the downslope we were very warm, almost 8 degrees above normal! Downslope is not conducive to wet conditions and we ended up with only 60% of normal November precipitation. The month ended with no snow on the ground at my house, a rare event.


Precipitation: Total for the month was 0.67 inches, 0.45 inches below normal. Snow only reached 11.4 inches, below the normal of 17.9 inches. Our snow events 5-8 and 21-22 Nov. were due to cold fronts creating some brief upslope and precipitation.


Temperature: Average high for the month was 47.3F with an average low of 30.9F. Both the high and low were much warmer than normal. These two stats combined to give us a + 8.6 departure from normal. In the 52 year record only November 1999 was warmer ( by a half a degree).


Winds: We consider a windy day as 40mph or stronger. We had a near record 19 days that qualified with four days at or over 60mph. Peak gusts got up near 80mph on Nov 1st and were near 70mph on the 20th. In the record there was only one November that exceeded this one: November 2014 with 20 days.


Other features: Winds on Nov 1st were quite destructive around the area with many felled trees, roof and window damage, and some spectacular waves in Barker Reservior. Same was true in the Nov 20th event to a lesser extent. The downslope lenticular clouds were spectacular. I can’t recall seeing so many stunning sunrise and sunset pictures. Snow over Colorado is very sparse. Ski areas are operating on mostly man-made snow. The warm temperatures haven’t helped.


Outlook for December: After the brief snow event earlier this week we will see a return of a huge west coast ridge that will bring very cold polar air to the eastern half of the US. Colorado will be on the edge of this airflow seeing mostly warm and dry conditions but an occasional push of cold in from the east and brief snows. By the last half of the month a return to warm and dry conditions is likely. Looking bleak for Christmas Eve snow.