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Forecast Discussion:
We have just about everything to discuss today- except for snow.
First, the fires of the western U.S. are still a growing problem with smoke levels increasing on west-southwest flow. Figure 1 shows the Utah smoke source making it to Longmont. The fires down south are adding a lot of smoke to the Great Plains.
Next, the zonal (west to east) jet stream flow still has small ripples (short waves) traveling down the stream. One of those is over Colorado today with a weak easterly flow at the surface bringing some more moisture into our eastern Plains (Figure 2). From these features, we have a chance of thunderstorms across the entire state (lighting is always a problem when fire danger is high!) and a marginal risk of severe weather returns backing up to I-25. Large hail and strong downdraft winds are the risk just to the east of us (unless the risk is expanded a few miles westward overnight); Figure 3.
The longer range forecast:
Tomorrow, the ripple is past and a moisture levels drop a bit. Our risk of severe weather is absent from the state. Just general afternoon thunderstorms are expected in spots (Figure 4).
That changes this weekend. Hurricane Bud (still a category 3 storm) is headed our way via southern Arizona (as a tropical depression); Figure 5.
Figure 6 shows the cool down (out of the 90'sF again) coming for the weekend as moisture levels increase. Moisture from Bud arrives and storm chances increase dramatically Sunday. A cool front pushes down, in the new week, further kicking up showers and strengthening up-slope moist air flow. If this model is correct (from weatherunderground.com) Longmont receives 1 1/3rd inches of rain before Thursday next week. Keep hoping! Let's get some help putting fires out, from above.
Figure 7 is the total precipitation thought Monday night. One can see a possible track of much of the moisture from Bud (from the GFS).
