Alert archive / Nebraska / Mesoscale Discussions in 2021
Mesoscale Discussion 607
The Storm Prediction Center issued this mesoscale discussion at May 13, 2021, 6:08 PM CDT for Cheyenne County, Rawlins County, Sherman County, Kansas; 6 counties in Nebraska. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 13, 2021, 6:08 PM CDT (23:08 UTC)
- Expired
- May 13, 2021, 8:15 PM CDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 20%
Counties Cheyenne County, KS, Rawlins County, KS, Sherman County, KS, Chase County, NE, Dundy County, NE, Hayes County, NE, Hitchcock County, NE, Keith County, NE, Perkins County, NE
The nearest sounding before it
N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 11.1 hours before the alert went out and 142 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 957 m above ground
- 0-6 km bulk shear
- 54 kt
- 0-1 km storm-relative helicity
- 306 m²/s²
- 0-3 km storm-relative helicity
- 262 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
853 ACUS11 KWNS 132309 SWOMCD SPC MCD 132308 NEZ000-KSZ000-140115- Mesoscale Discussion 0607 NWS Storm Prediction Center Norman OK 0608 PM CDT Thu May 13 2021 Areas affected...southwest NE and northwest KS Concerning...Severe potential...Watch unlikely Valid 132308Z - 140115Z Probability of Watch Issuance...20 percent SUMMARY...Swaths of large hail accompanying two supercells will likely extend south-southeast through 01 UTC. Localized severe gusts may also occur. DISCUSSION...Latest radar/satellite imagery shows two supercells over the central High Plains within an environment featuring steep low and mid-level lapse rates ahead of a mid-level shortwave trough. Latest Warn-on-Forecast suggests these storms will move south-southeast and probably intensify as the updrafts encounter slightly greater low-level moisture. However, observed storm motion and forecast Bunkers motion shows a more southward-component to motion than WoFs. Consequently, hail production will likely increase over the next hour and possibly maximize between 2330 UTC and 0100 UTC. Expecting hail potential to be highest with the storm over northwest KS (1.0 to 2.0 inches in diameter) with slightly lower overall hail growth potential with the storm west of North Platte. ..Smith/Grams.. 05/13/2021 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...GLD... LAT...LON 40000199 41580165 40540056 39180120 39170194 40000199
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 13, 4:48 PM CDT | Mesoscale Discussion | SPC | Cheyenne, Decatur, Rawlins | 117 min |
| May 13, 2:38 PM CDT | Mesoscale Discussion | SPC | Arthur, Banner, Box Butte, Brown, Cherry, Dawes and 8 more | 3 hr |
Nearby
Mesoscale Discussions in Nebraska, 2021Mesoscale Discussions in Kansas, 2021Every mesoscale discussion in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.