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In Brief:
Big fronts and little fronts are now going to flow across the state. Tropical moisture will feed into this more unstable environment (with short waves traveling by daily) and we should see rain now and then. We hang out with highs in the 80'sF for the next 8-10 days. Nice.
11am 9/6 Update:
With a big ridge to our south and a somewhat healthy passing short wave trough, we have a Marginal Risk of severe weather (Figure 1 update) along the Front Range today. Storms should be wandering after 2pm and before 7pm - mainly. Winds and hail are the primary risk. Carry on with your weekend!
End 11am 9/6 Update.
Forecast Discussion:
Our first cold front is sliding out of Wyoming and bringing in cooler air (Figure 1) today (Thursday). There is colder air aloft and moisture coming up into the West from the tropics (Figure 3). That means a better chance of afternoon storms everyday through Sunday (Figure 2). There might be a Marginal severe weather risk to the east of Denver Sunday, but nothing scary is expected around here.
The driver for this is the natural progression of the jet stream southward as Fall comes on. There is a march of short wave troughs (red) and ridges (blue) - Figure 4. In this image, you can see the Saturday short wave bearing down on us. Note the stronger cold fronts in Figure 2 are dark blue lines, and weaker cool fronts are light blue in Figure 2.
The Longer Range Forecast:
This cool, cloudy at times, and showery at times, weather continues through Sunday PM. We might see 1/4th to 1 inch of rain near Longmont (even if this model run puts a dry spot right on our head (Figure 5)). This will be a nice break from the heat. We dry out and stick with 80'sF for highs on through next weekend... and beyond?
Hurricane Dorian is still making big news as it slides from the South Carolina coastline to the North Carolina (NC) coastline and may make a brief landfall in NC late Thursday PM or early Friday AM. By the time I make my next full post on Saturday, it should be out east of New England out at sea headed for a Canadian landfall.
