Forecasters:Bruce Entwistle (NWS) and Morris Weisman (NCAR)
A weak surface front has passed through Goodland, and is currently located within the eastern portion of the STEPS domain. This front is associated with an upper level disturbance currently situated over central Wyoming. Cold air aloft behind the surface front along with mid 40s surface dewpoints and daytime heating will create modest instability over the Steps domain, with weak-to-moderate vertical wind shear. This upper-level wave will be progressing SE during the day, offering a trigger for weak-to-moderate convection during the afternoon and evening hours, with some small hail possible. Stronger convection is also possible just ahead of the surface cold front, but will be limited to the eastern most portions of the STEPS domain.
The earliest likely onset of convection is 2 pm (2000Z), lasting through early evening.
Warmer and drier Sunday and Monday, with little chance of convection.
| VARIABLE | Day 1: 1-4 pm | Day 1: 4-9 pm | Day 2 | Day 3 |
|---|---|---|---|---|
| Convective Potential |
1 | 1 | 0 | 0 |
| Storm Type | 1 | 2 | 1 | 1 |
| Triggering | 1 | 2 | 0 | 0 |
| Intuition | 0.5 | 0.5 | 0 | 0 |
| Total | 3.5 | 5.5 | 1 | 1 |
| SYSTEM | STATUS |
|---|---|
| Ops Center | Operational except for radio communication and T1 connection to S-Pol |
| CHILL | Operational. Final checking of polarimetric measurements dependent on the development of radar echoes. |
| S-Pol | Operational except for T1 connection and radio communication to Ops center. Radar scientist becoming familiar with scan controller. |
| LMA | Trailer near the WFO installed. Installation continuing on remote stations. |
| MGLASS | Not yet operational |
| T-28 | Expected to arrive this afternoon |
| Storm ballooning | Not yet operational |
| Mobile mesonet | Not yet operational |
| Storm chase van | Not yet operational |
| YRFS | Operational |
| NWS | Operational |
We would like for the two research radars to be ready to try some coordinated scans, provided echoes develop. The earliest convection will likely be shallow, with a remote chance of 30-40Kft deep cells.
Some widely scattered showers developed in the region by around 3pm MDT (21Z). Most had relatively high bases and topped out at about 5-6 km AGL (?, need to check if CHILL's readout was AGL or MSL). These cells eventually formed into a line southeast of the STEPS domain. Some hail (estimated 3-10 mm diameter) was reported near Colby as the squall line continued east-southeastward.
We opted not to do any coordinated scans between the radars. Instead we did scan setups separately so as to gain more experience and understand better the range of permissible operating parameters at each research radar. The main issues are being sure that the radar processors continue functioning when the number of samples is changed, and that the antennas can indeed scan at rates as high as 12 deg/sec (96 samples) without significant degradation of the polarimetric measurements. CHILL will use its so-called quick-scan mode at scan rates exceeding 8 deg/sec.
The SDSMT T-28 crew and airplane arrived this afternoon, and some equipment installation was completed at the Ops Center.
The NMIMT LMA now has 6 operating stations.