Forecasters: Mike (NWS) and Gilmore (NSSL/CIMMS)
Strong southerly flow is slowly returning low-level moisture to the STEPS domain today. A weak upper-level disturbance is moving across the region from the west, and is expected to generate a lee-trough/ dry line centered over the STEPS domain by late today. Cape values are expected in the range of 1000 j/kg just east of this dry line, but shear values are weak. There is a chance of isolated storms along the dry line late today and this evening, with one or two approaching severe limits.
Tomorrow, the dry/trough line is forecast to be positioned east of Goodland, with hot and dry conditions west of this feature. There is a slight chance of isolated convection east of this feature late in the day.
For Thursday, we begin to come under the influence of a deep trough moving onto the west coast, increasing mid-level and low-level moisture over the region and also reestablishing a surface dry line in eastern Colorado. This may increase convective potential for Thursday.
| VARIABLE | Day 1: 1-4 pm | Day 1: 4-9 pm | Day 2 | Day 3 |
|---|---|---|---|---|
| Convective Potential |
1.5 | 2 | 2 | 2 |
| Storm Type | 1 | 1 | 1 | 2 |
| Triggering | 0.5 | 1 | 0 | 2 |
| Intuition | -0.5 | -0.5 | -1 | 1 |
| Total | 2.5 | 3.5 | 2 | 7 |
| SYSTEM | STATUS |
|---|---|
| Ops Center | Operational. When needed both repeaters #1 and #2 will be devoted to mobile units, and the radars will use the regular telephones. |
| CHILL | Operational. |
| S-Pol | Operational. |
| LMA | Operational. |
| MGLASS | Operational. |
| T-28 | Operational. |
| Storm ballooning | The NSSL5 van is expected to return from Boulder by mid-to-late afternoon. NSSL5 data was successfully recovered from last Saturday's storm, and a UPS has been installed to avoid future problems. |
| Mobile mesonet | Five vehicles are operational. |
| Storm chase van | Operational. |
| YRFS | Operational. |
| NWS | Operational. |
OPS plan for today is for radars to begin surveilance at noon, with mobile units on standby starting at 2:00 pm. An MGLASS sounding will be taken in Burlington at 21Z to monitor the days potential.
Observations were obtained on two distinct storm systems. The first system consisted of relatively weak, high based convective cells which originated along a surface boundary to the NW at about 110 km from CHILL starting about 2 pm (all times MDT). Coordinated scanning between CHILL and SPol began about 3:00 pm. The T28 aircraft was called up at 5:20 as the system began to propagate SE, within the western dual-Doppler lobe at about an 80 km range from CHILL. Mobile mesonets also deployed under these cells for surface observations. The T28 completed 5 passes, oriented approximately NNE-SSW through two reflectivity cores between 5:55 and 6:55 pm. This storm system exhibited moderate IC lightning, but very little CG lightning. No hail was observed at the ground, with occasional large drops mixed with a variety of raindrop sizes. A possible wind gust of 30 m/s was noted by one of the mobile mesonets.
At 7:35 pm, radar emphasis shifted to another cell near Wray, Colorado, which was norht of and much stronger than the earlier targeted convection and which was exhibiting nearly 100 per cent positive CG lightning. This cell was propagating SE towards the eastern dual Doppler lobe, but decayed about 9:00 pm, before entering that lobe. SPol took sector scans of this cell from about 7:35 till its demise. No mobile mesonet observations were obtained.