The last Wednesday in June has arrived, the day when thousands of hard-working citizens take to the bike paths for their morning and evening commutes. Yes, it’s Bike to Work Day 2017 tomorrow! Five out of the last ten Bike to Work Days have seen measurable precipitation in Boulder. How does tomorrow’s forecast look for the Metro area? Read on to find out if the bikers will be getting wet this year….

Here is a short and sweet look at several factors impacting tomorrow’s Bike to Work Day forecast….

MID-LEVEL FLOW: The 500 mb map below shows almost due westerly flow across Colorado. This is downslope and definitely is not ideal for storm development.

LARGE-SCALE FORCING: The map below also shows a distinct lack of large-scale forcing with no troughs or ridges nearby, just zonal flow. Consider this flow pattern a wash…it doesn’t really support precipitation development, or hinder it.

MOISTURE: Statewide the available moisture tomorrow afternoon will be rather limited. Though the GFS is latching onto a tiny splotch of “elevated” moisture over Denver tomorrow, it’s far from ideal to support thunderstorms.

LOW-LEVEL FLOW: An extremely weak boundary will move into the area Tuesday night. While we hestitate to actually call this a cold front, it will drop high temperatures some 5 to 10 degrees for tomorrow compared to Tuesday afternoon. Highs will top out between 85 and 90 degrees for most locales across the lower elevations. This front will also usher in weak and shallow upslope at the surface. While in theory this is helpful for igniting storms, it’s very weak and we’re doubtful it will have much impact.

Overall forecast: Not a bad forecast for Bike to Work Day in general. While we can’t truly say you won’t run into rain out there, chances are fairly slim across the Denver Metro area considering all the factors above. Daytime heating will provide just enough energy to develop a few storms. Coverage will be isolated during the afternoon and evening, with the most likely time-frame for storms being 2PM to 8PM. Rainfall should be light in the storms that do form…most of it will be evaporating before it reaches the ground. 

BoulderCAST Podcast Episode #6: Bike to Work Day

A closer look….

7:00 AM: A few mid-level clouds with temperatures in the low 60’s.

10:00 AM: Mostly sunny with temperatures in the low to middle 70’s.

NOON: Clouds developing, but dry. Temperatures near 80 degrees.

3:00 PM: Partly to mostly cloudy with isolated thundershowers. Areas that remain storm-free will be in the upper 80’s this time of day. “Rainier” spots could be in the 70’s.

7:00 PM: Partly cloudy with chances of storms decreasing as the sun sets and they move eastward. Temperatures in the upper 70’s to low 80’s.


Have a safe and enjoyable ride everyone! 


Ben Castellani

Ben grew up in western Pennsylvania and holds both a bachelor's and a master's degree in meteorology. He currently works on a programming language tailored for scientists at Harris Geospatial Solutions in Boulder.

More Posts