June 7, 2016

Team Duck's Forecast:

"A low remains over the Hudson Bay/NE CONUS, while a departing tropical system is tracking off the east coast. Lee low development is expected across the upslope terrain, while most of the central plains remain under ridging, while a weak upper level ridge persists. Mid 50s dewpoints are current observable in SE CO and into the low 60s in the TX panhandle. These values are expected to advect northwestwards in an upslope flow regime over the Palmer Divide, front range and Cheyenne Ridge, which is already characterized by dewpoints AOA 50F. The limiting factor today will likely be the weaker upper level shear, with 30 knots effective BV shear (HRRR) suggesting the potential for weaker organization, unless the 1500-2500 J/kg of CAPE can offset this somewhat. Effective shear is better toward the southern end of the target, with this also being closer to the advected moisture source, and may involve formation of the DCVZ which will further promote cyclonic helicity on the north side of the Palmer.

CAMs from 11Z suggest a messier upscale growth storm mode with time, with initiation around Colorado O’Clock (20Z), though there appears to be some potential for supercell type echoes in Weld county from storms coming off the front range, while a second area sets closer to CO Springs. Current CAM dewpoints appear to be reasonably close to the real thing - this mornings synoptic analysis will come later as a second check of the moisture advection potential.

In light of this scenario, my suggestion would be a target INVOC Fort Morgan, CO, which places us well for a north or south correction toward either the Palmer, the Front Range or Cheyenne Ridge. Effective storm motion will likely be more west to east today, with right movers bending slightly SE. "

This chase amounted to a hill of beans... I mean ants. The only thing of interest as awaited storms near Keenesburg.

Team Duck's Summary:

"We woke to mostly clear blue skies and a coronation of western kingbirds out our hotel window. Like the previous two days, moist southeasterly upslope flow was in place. Moisture advected northwards by the low level jet during the previous night had lead to dew points in northeastern CO and southeastern WY as high as the mid 50s. This lead to the formation of 1500-3000j/kg CAPE, which, when combined with 30-35kts of effective deep layer shear, seemed likely to promote the development of organised storms off the Palmer Divide and Cheyenne ridge. However, 700mb temperatures were high, and were expected to rise further still over the course of the day, suggesting the potential for storms to struggle to become surface-based. Nonetheless, given the high terrain and favourable upslope flow environment, we targeted Fort Morgan, CO.

Cells failed to fire on the plains themselves, though initiation had occurred over the higher terrain, struggling to maintain updrafts as they moved from the high terrain over the plains. A shear convergence line was noted at DIA radar, just to the east of the airport. Cells were beginning to develop just to its west, and so we repositioned from Fort Morgan to Keensburg to position for any potential landspouts that might form.

Storms failed to materialise in the expected arc with anvil related cooling resulting in surface stabilisation. Given increasing CIN, it was decided that we call the chase near Wiggins CO and head north to better position for tomorrow’s event. We were afforded some pretty views of the orange sky through rain curtains and even a couple of lightning strikes as we pulled into our hotel for the night."