Forecasters: Morris Weisman (NCAR/MMM)
Today:
Although the day had been declared down at the Saturday (7/1) 9am briefing, the forecast for today now looks promising enough to call the project back up for operations. The normal operational day will resume on Tuesday, starting with a 9am weather briefing.
Deep moisture resides over the STEPS domain this morning, with surface dew points ranging between 55 and 60 F. Surface dew points near 70 F reside just east of the STEPS region. Surface and upper-level winds are light and variable. An upper-level disturbance is evident over the central Rockies this morning, and is forecast to move across the STEPS domain by evening. This system is expected to trigger widespread thunderstorms over eastern Colorado and western Kansas this afternoon and evening, producing localized heavy rain and pea size hail, but the lack of shear and only moderate amounts of instability reduces the chances for severe convection, except for the possibility of strong surface winds. The system may organize into a squall line, but cells within the squall line will be short-lived. Stronger convection may ensue once the system moves into the higher dew-points to the east of the STEPS domain, but these cells will also be short-lived.
Days 2 and 3:
For Tuesday and Wednesday, moisture and moderate amounts of instability are forecast to remain in place, with stronger uopper-level flow also forecast, assoiciated with disturbances propagating from southwest to northeast across the region, offerring some hope for more severe, organized convection.
| VARIABLE | Day 1: 1-4 pm | Day 1: 4-9 pm | Day 2 | Day 3 |
|---|---|---|---|---|
| Convective Potential |
2 | 2 | 2 | 2 |
| Storm Type | 0.5 | 0.5 | 1.5 | 1.5 |
| Triggering | 2 | 2 | 1 | 1 |
| Intuition | 0 | 0 | 1 | 1 |
| Total | 4.5 | 4.5 | 5.5 | 5.5 |
| SYSTEM | STATUS |
|---|---|
| Ops Center | Operational. |
| CHILL | Operational. |
| S-Pol | Unavailable since the day had been called down. |
| LMA | Operational. |
| MGLASS | One unit is operational. |
| T-28 | Engine failure, no longer available to the project. |
| Storm ballooning | Operational. Will run out of battery packs before running out of EFMs. |
| Mobile mesonet | Recalled to Norman, no longer available to the project. |
| Storm chase van | Unavailable. |
| YRFS | Operational. |
| NWS | Operational. |
The day has been declared back up for operations because of improved conditions for convection.
We are anticipating some development west of CHILL in the form of a squall-line with short-lived cells within the line. More severe, longer-lived convection is also likely, but east of Colby KS which will be a bit too far to be workable. We have mustered a skeleton crew for the Ops Center/CHILL, one MGLASS, the electrical ballooning unit, and 1the LMA. An environmental sounding will be taken at Goodland at 18Z.
A north-south oriented squall line storm developed west of a line from Limon to Akron CO. The line advected slowly eastward, with short-lived cells within the line advecting northeastward. There were two complexes east of Goodland, one southeast of Colby and the other in south central Nebraska northeast of McCook. Both of these complexes as well as the western squall line produced outflows that were expected to collide somewhere within the triple-Doppler triangle.
Around 2050Z, the ballooning unit came west to intercept the western squall-line, but it didn't hold together once the outflow had outrun the line itself. The line and all other echoes were covered with multi-elevation angle surveillance scans with RHIs every 5-10 deg along the line.
Operations were called down at 2356 Z.