Forecasters: ? (NWS) and Morris Weisman (NCAR/MMM)
A surface boundary is propagating westward through the STEPS domain this morning, bringing 10-15 mph easterly to northeasterly flow and dew points in the upper 50's to low 60's, enhancing the potential for significant CAPE further west and north than the past couple of days. Generaly, CAPEs are expected to be in the 1500-2500 j/kg range during the afternoon and evening.
An approaching upper-level disturbance and associated cold front will also enhance upper-level flow as the day goes on, especially in the northern portions of the STEPS domain, with shear magnitudes reaching minimal levels for supercellular activity by late afternoon or evening. As such, severe storms are anticipated, with strong surface winds and hail of 1-2 inch possible. Some cells could be supercellular later in the day. We will especially be looking for cells triggering to the northwest, along the Cheyenne ridge, and then propagting southeastward within research range of S-Pol.
For tomorrow (Sunday), the surface cold front will pass through the region, but surface dew points, CAPEs, and vertical wuind shears are forecast to remain high, again offering the possibility of severe storms and supercells within the research area.
For Monday, the cold front continues to proceed southeastward, reducing CAPEs and chances for severe convection somewhat.
| VARIABLE | Day 1: 1-4 pm | Day 1: 4-9 pm | Day 2 | Day 3 |
|---|---|---|---|---|
| Convective Potential |
2.5 | 2.5 | 2 | 1 |
| Storm Type | 1 | 2 | 3 | 3 |
| Triggering | 1 | 2 | 3 | 1 |
| Intuition | 1 | 1 | 0 | 0 |
| Total | 5.5 | 7.5 | 8 | 5 |
| SYSTEM | STATUS |
|---|---|
| Ops Center | Operational. |
| CHILL | Operational. |
| S-Pol | Operational. |
| LMA | Operational. |
| MGLASS | Operational. |
| T-28 | Operational. |
| Storm ballooning | Operational, but only seven EFMs remain with the possibility of refurbishing an additional five. |
| Mobile mesonet | Five vehicles are available. |
| Storm chase van | Operational as the primary precipitation verification vehicle. |
| YRFS | Operational. |
| NWS | Operational. |
Radars and mobile crews will be on standby for 1:00 pm. MGLASS soundings will be taken at Flagler CO, and Goodland KS at 18 UTC, with 21 and 00 UTC ascents also likely. Mobile ballooning crews will only launch into severe, positive CG storms or supercells today.
Radar-only coordinated scans were conducted mid afternoon on an isolated convective cell in the western dual-Doppler lobe. Fully coordinated operations with T28, mobile mesonets, electric ballooning units, and the hailstone van were conducted first on a small splitting cell just NE of S-Pol from 6 to 7pm (MDT), and then on a larger supercellular storm which developed near Yuma and propagated eastward over Wray and Haigler NE between 7 and 9pm. The later cells displayed reverse polarity, but initially did not produce much CG activity. However, the decaying supercell near Haigler produced extensive numbers of positive CGs between about 8 and 10pm. Electric ballooning units had two succesful launches on the supercell between Wray and Haigler. Scattered reports of hail up to 3/4 inch were reported with these cells, but no strong surface winds.
Coordinated observations were also taken with two DOW radars, which were located about 10 m N of Joes CO and 10 m S of Cope CO.