Alert archive / Nebraska / Mesoscale Discussions in 2017
Mesoscale Discussion 490
The Storm Prediction Center issued this mesoscale discussion at Apr 14, 2017, 4:17 PM CDT for 6 counties in Kansas; 7 counties in Nebraska. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Apr 14, 2017, 4:17 PM CDT (21:17 UTC)
- Expired
- Apr 14, 2017, 6:15 PM CDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
Counties Decatur County, KS, Gove County, KS, Graham County, KS, Norton County, KS, Phillips County, KS, Sheridan County, KS, Dawson County, NE, Frontier County, NE, Furnas County, NE, Gosper County, NE, Harlan County, NE, Phelps County, NE, Red Willow County, NE
The radar
The Grand Island radar (KUEX), 133 km from the middle of the area, began a volume at 21:21 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
N. Platte/Lee Bi, NE (KLBF), launched 12:00Z, 9.3 hours before the alert went out and 124 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
- 581 m above ground
- 0-6 km bulk shear
- 20 kt
- 0-1 km storm-relative helicity
- 218 m²/s²
- 0-3 km storm-relative helicity
- 419 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
382
ACUS11 KWNS 142117
SWOMCD
SPC MCD 142117
NEZ000-KSZ000-142315-
Mesoscale Discussion 0490
NWS Storm Prediction Center Norman OK
0417 PM CDT Fri Apr 14 2017
Areas affected...Southwest Nebraska through northwest Kansas
Concerning...Severe potential...Watch possible
Valid 142117Z - 142315Z
Probability of Watch Issuance...40 percent
SUMMARY...At least isolated storms are expected to develop from
northwest Kansas into southwest Nebraska early this evening. Large
hail and damaging wind will be the main threats. Trends will
continue to be monitored for a possible WW.
DISCUSSION...Early this evening a warm front extends from a surface
low over southwest NE, eastward through southern NE. A dryline
extends from the low through western KS. East of the dryline, strong
diabatic warming of the boundary layer where dewpoints are in the
upper 50s, has contributed to moderate instability with MLCAPE from
2000-2500 J/kg in the presence of steep low to mid-level lapse
rates. Visible imagery shows deeper cumulus increasing just east of
the dryline over western KS and in vicinity of the warm front across
southwest NE, and thunderstorms are expected to develop by 22 or
23Z. With only weak forcing aloft and presence of a capping
inversion at 800 mb associated with the elevated mixed layer, storm
coverage could remain somewhat limited. Effective bulk shear from
30-35 kt in the presence of moderate instability will support mostly
multicell as well as marginal supercell structures.
..Dial/Hart.. 04/14/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GID...LBF...DDC...GLD...
LAT...LON 41099991 40849913 40219897 39669928 38740026 38860079
39850080 40700086 41099991SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 14, 6:40 PM CDT | Severe Thunderstorm Watch | SPC | Adams, Boone, Buffalo, Clay, Custer, Dawson and 21 more | 5 hr |
Nearby
Mesoscale Discussions in Nebraska, 2017Mesoscale Discussions in Kansas, 2017Every mesoscale discussion in 2017
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; radar from the NEXRAD Level II archive.