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In Brief:
Today (Thursday) will be quite toasty, but, with our first of 3 cool fronts arriving, highs should fall short of 90F. We cool each day through Sunday when we have highs only in the 60'sF. There are some storm chances this afternoon, then good rain and thunderstorm chances Friday through Sunday. We warm up and dry out and might see our real first 90F+ day Wednesday or Thursday.
8:30am Update:
With peak heat today and a return of low level moisture (not to mention a lee trough and the upper air support of the approach of our weekend's trough) - the SPC has expanded the Marginal Risk (1 on a scale of 1-5) to include the mountains from the Divide eastward onto the Plains (Figure 1 update). Further out on the Plains, there is a Slight Risk (2 on a scale of 1-5). The primary threat in the Marginal Risk zone is for large hail and damaging winds with the stronger storms. In the Slight Risk zone, there is a chance for isolated tornadoes.
For Friday, the Slight Risk (hail and tornadoes and wind) is already back to I-25 communities from south of Denver up to about Loveland (Figure 2 update). The trend, often, is for the Day 2 forecast to expand westward once data comes in overnight. We'll watch this in the daily updates!
End 8:30am Update.
Forecast Discussion:
More rain has fallen. Thundershowers brought in another 1/3rd inch of rainfall to town Tuesday/Wednesday (Figure 1). We are still 100% drought free across Colorado.
Today (Thursday) high pressure dominates but a front is sneaking into the NE Plains to hit Longmont mid-afternoon. Friday's front is sweeping down across Utah and Wyoming today (Figure 2). There are some storm chances with this first front today but the risk of severe weather remains out on the Plains (but not too far away - Figure 4).
The Longer Range Forecast:
Our next, stronger front comes in midday Friday and rain and thunderstorm chances increase dramatically (Figure 3). The weatherunderground.com model gives us almost 1.5 inches of water over this weekend.
The (possibly the newly released, retooled) GFS at weather5280.com goes a bit crazy with rainfall totals with 5 to 20+ inches across northern Colorado over the next 5 days (this is an output error - Figure 5). The GFS at tropicaltidbits.com is more reasonable but gives Boulder over 2 inches and we almost reach 2 inches (Figure 6). This is looking wet.
And cold - snow levels should drop below 10,000 feet and maybe further down - Figure 7. I doubt Boulder gets a dusting though. More output error?
