Forecasters: Morris Weisman (NCAR/MMM)
Today:
The cool front that passed through the STEPS domain late last night into early this morning still lingers southeast of Goodland. It is expected to back some into the STEPS domain later in the day. So long as we maintain an easterly component to the surface wind along with dew points in the mid- to upper-sixties, the potential is moderate for severe convection. The convective temperature is about 95-97 deg.
Note: The 9am formal weather briefing and debriefing of the previous day's operations have been suspended. We will maintain a daily look at the weather, but no other briefings/debriefings will be conducted. The forecast matrix will no longer be posted.
The following research systems are all operational: the Ops Center, CHILL, S-Pol, LMA, MGLASS, and YRFS. These systems are all that remain available to STEPS. The LMA is scheduled to operate well beyond July 16 (the official last day of STEPS) in support of the TLE studies.
For the duration of STEPS in addition to the LMA, as a minimum, there will be one MGLASS unit for soundings, one S-Pol technician to assist Charlie Knight, and the complete staff for CHILL.
Miller never left Goodland last night. We are standing by for coordinated research radar scans today, Monday, July 10th. There will be an 18Z sounding at Goodland.
Around 1856Z, a line of CuCg and associated boundary echo developed south of CHILL and Goodland. By 2014Z we started coordinated scans on cells near and northeast of Limon CO. These cells all exhibited -CGs. At 2057Z we had shifted to cells SW in Cheyenne County CO. One of these had a mesocyclonic circulation signature, +CG, and had produced nickel-sized hail (62 dBZ at 208 deg from CHILL). We continued working these cells as they moved slowly eastward. In all we had 4 +CG storms from about 090 deg (150 km) around to 210 deg and 50-100km. At 2253Z we set up coordinated scans on cells in the eastern Doppler lobes. All cells were +CGs and very active electrically.
An intense storm with golfball-sized hail was reported in Yuma County, but was too far and in poor geometry for effective dual-Doppler work so we stayed with the cells in the eastern lobe. Once these eastern-lobe cells had begun to decay and were now about 50-50 +/-CG, we shifted to very rapidly growing +CG storms along the Nebraska-Kansas border west of Benkelman NE.
Other reports of note: wind gusts to 70 mph and 2.5 inch hail in northwest corner of Cheyenne County KS, also in northwest corner of Rawlins County KS, significant mesocyclonic signature in western most of these storms (Cheyenne Cnty one), 70 dBZ, a positive Zdr column, and a splitting storm east of Imperial Nebraska. Most storms around the perimeter of the 2D lightning mapping were +CGs at some time or another in their lifetimes.
All-in-all, it was a very active day with several storms reaching severe stages with large hail. However, most storms were fairly short-lived, perhaps 1/2-3/4 hour, but still intense in spite of the relatively low values of shear. A key was apparently a fairly deep layer of moisture. We took a couple of surveillance scans near the end and wrapped up operations at 0152Z. Soundings were taken at Goodland at 18, 21, and 24Z. The last sounding likely went through cloud.