Wednesday, July 02, 2008

20080702 Wx Discussion I (1840Z)


"I'm not sure exactly what they're seeing" ... that's what I said yesterday. They must have been seeing something I didn't, because there was a fair coverage of storms yesterday. While none of them ended up leaving much precipitation on the plains, I was surprised at how well convection initiated (even if it was high-based). Oh well, live and learn.

Today, we have much more moisture to work with at the surface. While dewpoints dropped into the low 30's yesterday afternoon, we're still sitting in the mid 40's today. Add in a little upper level support care of a short wave plowing off the Rockies to our north and the weak surface cold front that is in the process of moving through and we have a much better chance for storms today. Most of the models are drying out the metro area in the next few hours, but winds have shifted to a more easterly component which should advect more plains moisture into the area. We'll see which dynamic winds the battle.

Wind shear and support are greater to our north, so if I don't have to work at F2P2 today, I might try and join up with Tony Laubach for an afternoon chase on the north side. We'll see.


FORECAST: July 4th

A storm system will be moving in from the Pacific Northwest, bringing with it plenty of Pacific moisture. GFS and WRF-NAM-ETA all are showing dewpoints in the mid 50's in western Montana on Friday. The southwest corner of the state stays more dry and it looks like we'll see a bit of a quasi-dryline setup, probably banked against a mountain range like the Anaconda Range.

I'll be spending the day along the Big Hole River, near the town of Divide. Minor atmospheric capping will be in place in the morning, but convection should initiate with daytime heating and timing of the upper level support. Models are showing CAPE values up to 2500J/kg!!! I would wager that cumulus will develop progressively NW to SE over the course of the afternoon, with the first radar echoes showing up near 1PM. With the moisture available, steep lapse rates, and decent shear, severe weather is very possible. Hail up to an inch and a half could be possible as well as damaging winds in or around the mountains. I wouldn't rule out the possibility of a tornado in broader valleys where dynamics could really support a lone supercell.

I hope to see some of nature's fireworks along with the man-made pyrotechnics.


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