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In Brief:
The front has arrived and anchored itself to topography of Colorado. It is serving as a trigger for thunderstorms that will ride over the cooler air and feed on easterly up slope flow. We will cool to a low high temperature of around 77F Monday then return to seasonable warm weather with afternoon storms.
7:30am Update:
Wind shear (the change in direction and speed of winds at different heights of the atmosphere) and daytime heating (the stratus clouds are remaining further east that was expected yesterday) will be significant enough to create strong thunderstorms again today. A Marginal Risk of severe weather has been forecasted for the Front Range and much of eastern Colorado (Figure 1 update).
Hail and high winds (and a few spots of locally flooding rains) are the primary risk. We are still expecting 1/4-1/2 inch of water across the region mainly after 2pm on to late morning Monday with thunderstorms capable of dropping an inch or two in local spots.
Storms will be moving out of the northwest direction - so watch those dark skies and your weather alert apps!
End 7:30am Update.
Forecast Discussion:
Figure 1 shows that the SPC has expanded the Slight Risk (2 on a scale of 1-5) back to Hwy 287 and the first round of storms got pretty severe around Lyons. The front is visible anchored down the mountains almost to New Mexico (Figure 2). Monsoonal moisture from the southwest and Mexico is leaking into the state from the south (Figure 3).
The cooler air Sunday will inhibit severe weather but rain and thunderstorms are still possible (Figure 4). By 6am the HRRR gives us a about 1/4th inch more than we received mid afternoon Saturday (Figure 5).
The Longer Range Forecast:
The weatherunderground.com site gives us a bit more than 1/2 inch more rain on Sunday and maybe 1/10th inch up to Monday (not shown). The GFS gives us 3/4th of an inch to 1 inch over the next 48 hours (Figure 6).
We hover just above and just below the 90F mark Tuesday through the next weekend with a return of afternoon thunderstorms.
