October 2021 was extremely dry for all of eastern Colorado and drought has exploded once again across the region. Other notable highlights during the month include the return of La Niña for a second winter in a row, magnificent fall colors, a drizzly Halloween, and the lack of any accumulating snowfall yet in Boulder or Denver. Here’s a quick and colorful graphical recap of our weather during October and how it relates to climatology.
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HOLY GRAUPEL! A wave of cold thunderstorms bubbled up over the Boulder area on October 12th producing pockets of accumulating graupel across the region. Accumulating graupel in lower elevations is fairly rare, so it’s no surprise these little white balls of snow were misidentified as hail by many. Interesting fact: graupel actually does count as snow, so this event was the first snowfall of the season for many locations of eastern Boulder County. Neither Boulder or Denver officially reported accumulating graupel, though.
What accompanied last night's cold thunderstorm was graupel, not hail or snowflakes. However, graupel does technically count as snowfall. If you're area saw a coating of graupel last night like this (0.1"+), congratulations. You just had your 1st snowfall of the season! #COwx https://t.co/oBAJaUgGkF
— BoulderCAST Weather (@BoulderCAST) October 13, 2021
A SECOND HELPING OF LA NINA: La Niña officially returned during the month of October after months of waiting for the sea-surface temperature forecast to take shape. This will be the second winter in a row with an active La Niña in place. If you missed our autumn and early winter outlook, be sure to catch up HERE. The TL;DR, expect generally warmer and drier that normal weather to persist through the end of 2021 (at least).
La Niña is set to return for a second winter in a row, but what does this mean for Colorado and Boulder?
We discuss the forecast, recent outcomes, and potential impacts on our weather:https://t.co/NsJv7EBM8a#COWx #LaNiña #Autumn #Snow #COsnow #Boulder #Denver #ENSO #LaNina
— BoulderCAST Weather (@BoulderCAST) October 13, 2021
SUPERB YELLOWS & REDS: Owing in part to the warmer days and lack of any early season snow or freezing temperature , the fall colors this year across the Metro area have been astounding! By our account, this was the best October for fall colors since at least 2016, possibly longer. We hope you took a moment or three to enjoy them! It’s a rarity that Mother Nature provides such favorable conditions for this stunning of colors.
The fall colors were superb a few days ago. By now, most have just blown away… #COwx #Autumn #Denver #Boulder pic.twitter.com/6WzCxBfCDy
— BoulderCAST Weather (@BoulderCAST) October 27, 2021
A DRIZZLY HALLOWEEN: Halloween is famously known as the time of year when our first snowfall usually occurs (which does have some minor underlying truth to it), but this year it wasn’t snowing on Halloween. Low clouds and drizzle were observed across the Denver Metro area on the 31st as a chilly cold front banked up against the terrain. Boulder struggled but ultimately did reach 40 degrees during the afternoon hours while reporting 0.01″ of drizzle on the final day of the month. The day before it was in the 70’s…
Stay warm on this chilly and gloomy Halloween! #COwx #Boulder pic.twitter.com/mt0SPbPvLH
— BoulderCAST Weather (@BoulderCAST) October 31, 2021
A RESURGENCE OF DROUGHT: Boulder officially recorded just 0.17″ of rainfall during the month of October and just a trace of snowfall. This bone-dry offering was good enough for the 5th driest October in Boulder since the late 1800’s, and the driest since World War II. Denver saw even less precipitation at 0.08″. Over the last 60 days, eastern Colorado has been absolutely parched.
During the month of October, we’ve really seen drought coverage blow up again across eastern Colorado with 77% of the state now experiencing at least Moderate Drought. This is up from 46% just six weeks ago.
October 2021 Recap Graphics:
Where does October 2021 fit into the last 12 months?
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