Forecasters: (NWS) and Clay Morgan (NWS)
Low-level moisture remains in place over the STEPS domain this morning, with a lee-trough also evident over eastern and northeastern Colorado. A large area of altocumulus and associated showers extends from the front range northeastward associated with this trough feature. Daytime heating along with localized lifting associated with the trough feature and weak upper-level disturbance propagating from the southwest will produce a high chance of significant convection by early-to-mid afternoon, extending through this evening. Some cells may be severe, with hail possibly up to 1 inch. However, vertical wind shear magnitudes are too weak for supercellular activity.
For tomorrow (Saturday), moisture and instability will remain in place, with an upper-level disturbance and associated cold front approaching from the northwest later in the day. Shear magnitudes may increase to marginal values for supercells in the northern portions of the STEPS domain by late in the day. Significant convection, possibly severe, is expected within the STEPS research domain.
For Sunday, the surface cold front is forecast to have passed east of the STEPS domain, reducing chances for significant convection.
| VARIABLE | Day 1: 1-4 pm | Day 1: 4-9 pm | Day 2 | Day 3 |
|---|---|---|---|---|
| Convective Potential |
2.5 | 2.5 | 2 | 1.5 |
| Storm Type | 1 | 1 | 2 | 1.5 |
| Triggering | 2 | 2 | 2 | 1 |
| Intuition | 0.5 | 1 | 1 | 0 |
| Total | 6 | 6.5 | 7 | 4 |
| SYSTEM | STATUS |
|---|---|
| Ops Center | Operational. |
| CHILL | Operational. |
| S-Pol | Operational. |
| LMA | Operational. |
| MGLASS | Operational. |
| T-28 | Operational. |
| Storm ballooning | Operational. |
| Mobile mesonet | Single vehicle with the rest unavailable since no supercells are expected. |
| Storm chase van | Operational as the primary precipitation verification vehicle. |
| YRFS | Operational. |
| NWS | Operational. |
Radars and mobile teams are requested to be on standby by 1:00 pm in anticipation of significant convection this afternoon. MGLASS soundings will be taken at 18 UTC in Stratton CO and Colby KS, with additional soundings possible at 21 and 00 UTC.
Dave Rust reports 7 remaining EFM's currently, with some hope of recovering a couple more.
Operations centered on a multicellular line of marginally severe storms that developed from southwest of CHILL northeastward to near Goodland. Heavy rain with occasional pea-to-dime size hail and surface winds up to 30 m/s were reported with some of these cells. Radar operations concentrated coordinated scans on cells developing in the triple Doppler triangle and then within the eastern dual-Doppler lobe. The cells did not produce a lot of CGs, but were predominantly positive in polarity. The T28 was called up at 4:00 pm, and did transects of the convective cluster between 4:30 and 5:30 pm. One mobile mesonet and the hailstone van sampled the cells while the T28 was on station. No mobile electric balloons were launched, as it was decided that the convection was too disorganized. Operations shut down at 6:00 pm.