July 4, 2010 I-80 WY-NE severe storms

I’ll make it easy on myself and just paste the CFDG post by me for this chase day:

The last chase day for me is today, and it will be in the good ol’ USA!

The potential for a supercell and maybe a tornado looks pretty darn good in the vicinity of Weld County, CO, late this afternoon. Dews along I-80 from CYS to SNY are 55 – 60F, and the RUC shows nicely backed flow of 15-25 knots through Weld County by 00Z. This area will be beneath WSW flow at 30 knots at 500 and southerly flow at 15-20 knots at 700. CAPE is forecast to be above 1500 from Fort Collins to Chugwater.

Another area to watch today will be the Palmer Divide sw of LIC and perhaps the Raron Mesa area to Baca County, with really juicy air lurking nearby (65F dew at DHT and 67F at EHA).

The big player today will be Mr. Sun —- it is imperative that the high terrain along and just east of I-25 receives several hours of mid-afternoon high-grade insolation. Currently much of E WY and E CO is overcast, but there is a decent swath of clear skies around Weld County. We are diving south from Chadron, and I’m looking for storms to move into the Kimball/Fort Collins/Chugwater area off of the higher terrain by 22Z-00Z.

A strong storm started to rotate and move east towards I-25 between Cheyenne and Chugwater, and I wrote at 2045Z:

2045Z—-we got right in front of the trailing t-warned cell S of Chugwater and viewed—–not much. There is a lot of low stratus around, the storm base was low and murky, and there wasn’t much cloud motion to get excited about, despite the good-looking velocity couplet. Conditions were quite cool with near 100 percent RH. The RFD came overhead and we had 3/4-inch size hail.

We are heading back south to catch something moving into warmer air.

We dropped back south to Cheyenne and east on I-80.  There were reports of tornadoes with the storm that went over us near Chugwater, and with another storm over Cheyenne when we were nearby.  We saw no tornadoes.  We played with other marginally-interesting convection along I-80, but they tended to be outflowish or just plain duds.   A discrete cell north of the interstate decided to bolt into Nebraska, and we caught up in time to watch it elongate and weaken.  The chase was over, we headed to Denver to drop the guests off at the motel, and I was a free man until CHASE 2011!