Forecasters: David (NWS) and Morris Weisman (NCAR)
Residual moisture behind a large MCS over central and eastern Kansas along with cold temperatures aloft maintains moderate instability over much of the STEPS domain today. However, vertical shear values have decreased, reducing chances of supercellular convection. A weak upper- level disturbance is propagating eastward from western Colorado and Wyoming during the day, and may serve as a trigger for convection later in the day. Most probable region for significant convection is within the northern sector of the STEPS domain from mid-afternoon through early evening, with the most significant cells expected to move east or southeast at 15-25 mph.
The progressing upper-level wave will produce subsidence and drying over the STEPS region Saturday and Sunday, with little chance of any convection either of these days.
| VARIABLE | Day 1: 1-4 pm | Day 1: 4-9 pm | Day 2 | Day 3 |
|---|---|---|---|---|
| Convective Potential |
1 | 2 | 0 | 0 |
| Storm Type | 1.5 | 2 | 1 | 1 |
| Triggering | 1 | 1.5 | 0 | 0 |
| Intuition | 0.5 | 0.5 | -1 | -1 |
| Total | 4 | 6 | 0 | 0 |
| SYSTEM | STATUS |
|---|---|
| Ops Center | Operational. We will use repeater #2 for coordinating radars, with telephones as a backup. Repeater #1 (normally the mobile ground-to-ground) is not yet operational. Will use telephones to coordinate mobiles. |
| CHILL | Fully operational. |
| S-Pol | Fully operational. |
| LMA | Fully operational with on-site recording. Some interference on TV channel 3 from some distanct broadcast station. Work will continue on wireless internet for real-time analysis at Goodland base station. |
| MGLASS | Operational, soundings now available from the NCAR/RAP web page. |
| T-28 | Operational. |
| Storm ballooning | Operational. |
| Mobile mesonet | Six vehicles are now operational. |
| Storm chase van | Operational except that the GPS doesn't work, will tag along with mobile units. For weather safety purposed, we are dispatching an NWS volunteer with the mobile chase van since they are EE students. |
| YRFS | Operational |
| NWS | Operational |
We will have the Ops Center and SPol fully staffed and operating by 12am MDT. The mobiles will standby for a 1pm update. Some weaker convection is likely, with no potential for severe storms. The most likely region for convection is northwest off the Cheyenne Ridge along the Wyoming-Colorado border.
We dispatched the mobile mesonet and sounding crews north to St. Francis Kansas in anticipation of getting ahead of the first convection coming off the Cheyenne Ridge along the Colorado-Wyoming border. This convection moved eastward, but remained rather disorganized. Better organized and more intense cells moved into the STEPS domain from due west of CHILL around 1500 MDT. We committed all resources to these storms. These was 1/2 inch hail reported near Flagler CO (west of CHILL on I-70) at 15:30 MDT. Scans were first taken across the full western Doppler lobe, with the most intense cell south of this region. Visually from CHILL this entire system had very well defined cloud bases, with a small wall cloud west of CHILL but a broader one associated with the storm farther south. As cells within the western lobe of the research were decaying and the storm to the south was intensifying, we committed to this storm.
It passed south of CHILL in a less than ideal geometric position. The T-28 made one successful pass through one of the reflectivity cores before it had an equipment failure, likely as a result of being struck by lightning. The mobiles and ballooning were dispatched eastward toward Colby KS to get ahead of the storm. By around 1645 MDT several outflow boundaries had collided and triggered new convection throughout most of the STEPS domain. Since there were no obvious regions to focus on, we went into a WSR88D-like scan mode of full 360 deg scans by both research radars. Excellent polarimetric data was taken where CHILL did the hybrid (simultaneous H and V transmissions) mode alternately with the normal H then V transmission.
These 360 deg scans continued until 18:30 MDT when we secured operations because most of the convective cells were well to the east of the STEPS domain.