Alert archive / Nebraska / Mesoscale Discussions in 2012
Mesoscale Discussion 912
The Storm Prediction Center issued this mesoscale discussion at May 26, 2012, 2:55 PM MDT for Sedgwick County, Colorado; 13 counties in Nebraska; 5 counties in Wyoming. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- May 26, 2012, 2:55 PM MDT (20:55 UTC)
- Expired
- May 26, 2012, 5:00 PM MDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 60%
Counties Sedgwick County, CO, Arthur County, NE, Banner County, NE, Box Butte County, NE, Cheyenne County, NE, Deuel County, NE, Garden County, NE, Keith County, NE, Kimball County, NE, Lincoln County, NE, Morrill County, NE, Perkins County, NE, Scotts Bluff County, NE, Sioux County, NE, Converse County, WY, Goshen County, WY, Laramie County, WY, Niobrara County, WY, Platte County, WY
The radar
The Cheyenne radar (KCYS), 123 km from the middle of the area, began a volume at 21:00 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
Denver, CO (KDNR), launched 12:00Z, 8.9 hours before the alert went out and 230 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
- 1629 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- 147 m²/s²
- 0-3 km storm-relative helicity
- 148 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
815
ACUS11 KWNS 262055
SWOMCD
SPC MCD 262055
NEZ000-COZ000-SDZ000-WYZ000-262300-
MESOSCALE DISCUSSION 0912
NWS STORM PREDICTION CENTER NORMAN OK
0355 PM CDT SAT MAY 26 2012
AREAS AFFECTED...PORTIONS SERN WY...WRN NEB...EXTREME N-CENTRAL/NERN
CO.
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 262055Z - 262300Z
PROBABILITY OF WATCH ISSUANCE...60 PERCENT
SUMMARY...POTENTIAL IS INCREASING FOR DEVELOPMENT OF SVR
TSTMS...INCLUDING RISK OF SUPERCELLS AS WELL AS BOWING SEGMENTS.
FULL SPECTRUM OF SVR IS POSSIBLE.
DISCUSSION...20Z SFC MESOANALYSIS SHOWED CYCLONE BETWEEN
DEN-GXY-FCL...WHICH SHOULD MOVE/REDEVELOP NNEWD OVER WY/NEB BORDER
THROUGH 03Z. VERY SHARPLY DEFINED WARM FRONT WAS DRAWN FROM LOW
ENEWD NEAR LBF-ODX-OFK LINE...AND WILL MOVE NWD OUT OF NERN CO AND
OVER WRN/CENTRAL NEB IN STEP WITH SFC LOW. DIFFUSE/DOUBLE DRYLINE
STRUCTURE WAS ANALYZED FROM FRONT SWD ACROSS ERN CO AND WRN
KS...WITH MOIST AXIS EXTENDING FROM SRN SANDHILLS TO N PLATTE RIVER
VALLEY OF WY. CONSIDERABLE CONFLUENCE ALSO WAS NOTED IN LATTER
AREA...WHICH MAY REMAIN UNTIL MERGING WITH NWD-MOVING WARM-FRONTAL
ZONE. BACKED FLOW FROM THAT AREA EWD OVER PANHANDLE AND SWRN
NEB...PRIOR TO WARM FROPA...WILL MAINTAIN ENHANCED LOW-LEVEL
SHEAR/HODOGRAPH SIZE IN SUPPORT OF SUPERCELL POTENTIAL FOR ANY
RELATIVELY DISCRETE CONVECTION IN THAT REGIME. ELY/UPSLOPE FLOW
ALSO WILL REPRESENT LOW-LEVEL ASCENT IN SERN WY CONFLUENCE ZONE.
N OF WARM FRONT...VIS IMAGERY SHOWS MARKED CLEARING OVER LARAMIE
COUNTY WY...SPREADING NWD ACROSS SRN PORTIONS PLATTE/GOSHEN
COUNTIES...AND SPREADING NWD ACROSS APPROXIMATELY SRN 1/2 OF NEB
PANHANDLE. RELATED INSOLATION WILL ACT ON SFC DEW POINTS 50S F AND
STEEP MIDLEVEL LAPSE RATES TO SUPPORT ROUGHLY W-E ORIENTED CORRIDOR
OF 1500-2500 J/KG MLCAPE...JUXTAPOSED WITH 50-60 KT EFFECTIVE SHEAR
MAGNITUDE. AIR MASS FARTHER N...ESPECIALLY FROM DGW-TOR-AIA LINE
NWD...HAS BEEN ENSHROUDED IN THICK LOW CLOUDS FOR MUCH OF
TODAY...WITH SOME DISPERSAL ONLY RECENTLY NOTED IN VIS IMAGERY.
THIS AREA WILL TAKE LONGER TO DESTABILIZE...THOUGH AREAS AS FAR N AS
EXTREME SWRN SD AND NEWCASTLE REGION MAY BECOME FAVORABLE BEFORE
DARK. CORRIDOR BETWEEN GCC AND CENTRAL BLACK HILLS WILL REPRESENT
SW-NE GRADIENT WITHIN WHICH MLCAPE WILL DIMINISH MARKEDLY. AS
SUCH...PERSISTENCE OF SFC-BASED EFFECTIVE INFLOW PARCELS BECOME MORE
UNCERTAIN AS FAR N AS I-80. RELATED CINH ALSO WILL BE SLOW TO ERODE
OVER CENTRAL/NRN SANDHILLS OF NEB...LEADING TO RELATIVELY LOWERED
NEAR-TERM SVR PROBABILITIES THERE.
..EDWARDS/CARBIN.. 05/26/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LBF...UNR...BOU...CYS...RIW...
LAT...LON 40840488 41650496 42260514 42680538 42820588 42890613
43380519 43360393 43060335 42300314 41660212 41510074
41090062 40560078 40740215 40770405 40840488SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 26, 1:46 PM MDT | Mesoscale Discussion | SPC | Baca | 119 min |
| May 25, 8:17 PM MDT | Mesoscale Discussion | SPC | Adams, Boone, Buffalo, Burt, Butler, Cass and 43 more | 88 min |
| May 25, 11:46 PM MDT | Mesoscale Discussion | SPC | Burt, Dakota, Thurston | 89 min |
| May 26, 12:58 AM MDT | Mesoscale Discussion | SPC | Boyd, Holt, Keya Paha, Knox, Rock | 92 min |
| May 26, 2:48 PM MDT | Mesoscale Discussion | SPC | Adams, Antelope, Boone, Buffalo, Burt, Butler and 50 more | 87 min |
| May 26, 3:48 PM MDT | Severe Thunderstorm Watch | SPC | Arthur, Blaine, Boyd, Brown, Cherry, Custer and 15 more | 5 hr |
| May 26, 5:44 PM MDT | Mesoscale Discussion | SPC | Arthur, Blaine, Brown, Cherry, Garden, Garfield and 9 more | 91 min |
Nearby
Mesoscale Discussions in Nebraska, 2012Mesoscale Discussions in Wyoming, 2012Mesoscale Discussions in Colorado, 2012Every mesoscale discussion in 2012
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.