Check Out This Radar Echo

[Tony Laubach]

http://www.crh.noaa.gov/radar/loop/DS.p19r...0/si.kftg.shtml

I'm looking at this and wondering.. we have a large band of preceip moving in from the east, crashing right into the foothills where a larger band of precip is going due north. That's kind of cool!

Also worth a note; how the convection intesifies where this collides. For you newbie forecasters and future weather nerds, this is a great example convergence via radar! 8)

 

[Tim Stoecklein]

I bet you can't tell where the divide is :wink: I'm liking the national radar, can you tell where the front is???

Tim

 

[Glen Romine]

Also worth a note; how the convection intesifies where this collides. For you newbie forecasters and future weather nerds, this is a great example convergence via radar! 8)

Sorry Tony, but I think there is a better way to interpret this. I think what you are seeing here is two layers of precipitation - the lower layer is rather shallow, generating drizzle within the upslope flow, and this is overlain by a deeper precipitating layer which includes some mesosclae banding features, moving toward the NNE. Look at the sounding from Denver this morning:

http://www.rap.ucar.edu/weather/upper/dnr.gif

There is a shallow neutral layer from the surface to around 800 mb - which with the forced upslope now present from veering wind profiles since this mornings sounding should support drizzle. The latest surface obs in fact support the presence of drizzle:

http://www.rap.ucar.edu/weather/surface/di...on=den&nplots=1

Back to the sounding, there is a conditionally unstable layer from 600-460 mb, and this layer could support the banded precipitation. The cloud top is sufficiently cold to be ice process rain, with a typical melting signature in the sounding below 600 mb (the nearly isothermal layer from 600-700 mb). Note that a surface parcel, if forced to ascend, never achieves positive buoyancy, so it is very unlikely the more substantial precip is surface air (well, the drizzle layer) from the east converging into the mountains and being lifted to form the rain. The GJT sounding popped early, but shows plenty of moisture on the west side of the Front Range - so I'd expect the rains in your area to be from forced ascent of moist air coming from the west side, not the east.

Glen

 

[Tony Laubach]

Glen,

Thanks dude, and wow! Good explanation! I take that back newbies, follow up on Glen's explanation. He knows what he's talking about! Still a cool looking radar, but Glen has nailed down a much better explanation on why that's happening!

My original reason for this post was to get an explanation on how that's working. I figured it to be convergence, but didn't think about the layering. That makes better sense now that you've put some umph into that.

Thanks Glen! Kudos to ya!