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Wed Update: The Front Range Forecast: Smoke now, storms later

Smoke for a bit longer, clearer air and afternoon thunderstorms begin.

In Brief:

Smoke for a bit longer, clearer air and afternoon thunderstorms begin.

Wednesday Update:

Change is coming to the weather today! There is about a 40% chance of a thunderstorm this afternoon. There is also a chance that the storms today may reach severe levels with hail and high winds being the primary threat (Figure 1 update).  The air coming in behind these storms should be more from the southwest and noticeably improve our air quality, cleaning out the smoke from the ongoing Canadian fires.

We have a lower chance of thunderstorms on Thursday, and a better chance, again, on Friday.  The storms on these days may reach severe levels as well, with hail and high winds still the primary threat. But you'll be able to breath easier!

Figure 1 update: the Day 1 SPC severe weather forecast for Wednesday.

End Wednesday update.

The Forecast Discussion:

After a few Saturday afternoon showers, the weather turns calm for a couple of days (Figure 1). The real problem is smoke.  Giant forest fires in Canada (and Mexico) are pumping the westerlies full of smoke (Figure 2). By Sunday, another surge of very bad air is headed our way (Figure 3).  Eventually, westerly then southwesterly winds will clean the air by mid- week and later in the week.

Figure 1: the 10 day graphical forecast for Denver from
Figure 2: the RAP smoke forecast for Wednesday PM from NOAA.
Figure 3: the RAP smoke forecast for Thursday PM from NOAA.

The Longer Range forecast:

With increased tropical moisture and southerly winds, the smoke will clear and rain chances will increase in the afternoons starting Tuesday (Figure 4). Wandering storms will give the I-25 folks a tenth to a quarter of an inch of rain over the next 5 days - more rain for the mountains (Figure 5).

Figure 4: the surface precipitation forecast map for Tuesday PM from tropicaltidbits and the GFS model
Figure 5: the 5 day precipitation forecast from the GFS and