A dry line/lee trough has set up over the western STEPS domain this morning, with dew points in the upper 50's to low 60's east of the dry line, and mid-40's dew points to the west. A mid-tropospheric wave is also propagating through northeastern Colorado this morning as evidenced by enhanced mid-level cloudiness over the region. A strong upper-level disturbance and associated surface cold front extends from western Colorado through northern Wyoming. The initial mid-tropospheric disturbance is forecast to pass through the STEPS domain by early afternoon, pushing the surface dry line eastward to near Colby by early afternoon. The chances for significant convection will remain along and east of this dry line position, with early convection a possibility as the dry line and initial wave first pushes eastward. Later today, the more energetic upper-level disturbance and associated cold front will be approaching the STEPS region, triggering more convection, but the potential for severe convection will be limited to along and east of the dry line, near Colby. Shear magnitudes will be marginal for supercell activity, but supercells can not be ruled out east of the dry line.

For tomorrow, the surface front is forecast to be located in southern Kansas, with easterly flow forecast over the STEPS region. Residual surface moisture behind the front along with some additional upper-level forcing associated with the deep wave to the north may produce some additional convection, although severe convection is unlikely.

For Wednesday, high presure noses further southeast over the region, reducing the chances of convection further.

    Forecasters:Vincent (NWS/GLD) and Morris Weisman (NCAR/MMM)

Post the wx briefing here

All systems have been placed on standby as of 12:00 pm for possible early operations in the eastern portions of the STEPS domain. 18Z soundings will be taken in Stratton CO and Colby KS. 21Z soundings may shift further east. PI's discussed the possibility of targetting storms east of the 3D lightning mapping area today, and all agreed that such observations would be valuable as long as we do not go beyond the 2D limits, approximately 150 km east of the Kansas border.

[Radar images]

On Monday, after much waiting along the dry line near Colby KS operations were conducted on a severe, high-based, and electrically active storm complex that was originally generated near Colorado Springs and which passed through the core of the STEPS domain between 5:30 pm MDT and 8:00 pm MDT. Surface winds of 70-75 mph were observed in many areas in association with this storm. Coordinated radar observations began on this storm complex about 5:15 pm, when the system was about 60 km SW of CHILL. A decision to target this storm with the T28, electric ballooning units, and Mobile Mesonets was made at 6:10 pm.

The T28 completed about 6 passes through the storm between 6:40 pm and 7:40 pm as it propagated from the CHILL site to northeast of Goodland. One electric balloon was launched from the Goodland WSFO into the leading anvil of the storm at about 7:10 pm, and an additional balloon was launched behind the storm at 7:50 pm. Launches into the core of the storm were curtailed due to 70-75 MPH surface winds. The mobile mesonets began transects of the storm starting about 4 miles west of Goodland. Other than the strong winds, the mobile mesonets did not document any hail. Other reports suggested occasional observations of pea-size hail. The storm system exhibited a large amount of IC lightning, but only a modest number of CG strokes. The CG strokes were predominantly of negative polarity.

MGLASS soundings were taken at 18, 21 and 00 UTC near Straton CO and near Colby KS. An additional sounding was launched from Colby at 1:30-2:00 UTC as the 00 UTC sounding was partially lost due to power problems.

Radar observations ended at 8:20 pm, as the storm system propagated east of the eastern lobe.

Additional severe storms were triggerred as this system propagated across the dry line near Colby KS, with hail up to quarter size and two brief tornadoes reported in the vicinity of Hoxie KS. STEPS observations were not taken on these storms.