Alert archive / Oklahoma / Mesoscale Discussions in 2012

Mesoscale Discussion 1992

September 26, 2012Sebastian County, Arkansas; 13 counties in Oklahoma

The Storm Prediction Center issued this mesoscale discussion at Sep 26, 2012, 2:04 PM CDT for Sebastian County, Arkansas; 13 counties in Oklahoma. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued: Sep 26, 2012, 2:04 PM CDT (19:04 UTC)
Expired: Sep 26, 2012, 3:30 PM CDT
In force: 86 min
Issued by: the Storm Prediction Center
Chance of a watch: 40%

Counties Sebastian County, AR, Cleveland County, OK, Haskell County, OK, Hughes County, OK, Latimer County, OK, LeFlore County, OK, Lincoln County, OK, Logan County, OK, McIntosh County, OK, Okfuskee County, OK, Oklahoma County, OK, Pittsburg County, OK, Pottawatomie County, OK, Seminole County, OK

The radar

The Norman radar (KTLX), 76 km from the middle of the area, began a volume at 19:07 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.

Severe Thunderstorm Watch 651Sep 26, 2:20 PM CDT

The nearest sounding before it

Norman, OK (KOUN), launched 12:00Z, 7.1 hours before the alert went out and 88 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 51 J/kg
Mixed-layer CIN: -540 J/kg
Mixed-layer LCL: 1962 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 72 m²/s²
0-3 km storm-relative helicity: 367 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

503 
ACUS11 KWNS 261904
SWOMCD
SPC MCD 261904 
ARZ000-OKZ000-262030-

MESOSCALE DISCUSSION 1992
NWS STORM PREDICTION CENTER NORMAN OK
0204 PM CDT WED SEP 26 2012

AREAS AFFECTED...CENTRAL/EASTERN OK

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 261904Z - 262030Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...AT LEAST AN ISOLATED SEVERE THREAT WILL EXIST THIS
AFTERNOON ACROSS PORTIONS OF EASTERN/CENTRAL OK. SEVERE
HAIL/DAMAGING WINDS WILL BE POSSIBLE...AND A BRIEF TORNADO CANNOT BE
RULED OUT.

DISCUSSION...A RECENT INCREASE IN STRONG TSTMS HAS OCCURRED ACROSS
EAST-CENTRAL OK NEAR I-40...NEAR THE HENRYETTA VICINITY AS OF 1845Z.
THIS DEVELOPMENT IS OCCURRING NEAR AN OUTFLOW BOUNDARY THAT ROUGHLY
EXTENDS WEST-EAST ACROSS OK...WITH OTHER TOWERING CU NOTED IN
VICINITY OF THIS BOUNDARY ACROSS CENTRAL OK IN LATEST VISIBLE
SATELLITE IMAGERY. THE PURCELL OK PROFILER REFLECTS AROUND 35 KT OF
0-6 KM...WHICH IS MORE THAN ADEQUATE FOR A SUPERCELLULAR/SUSTAINED
STORM MODE ESPECIALLY NEAR THE OUTFLOW BOUNDARY WHERE LOW-LEVEL
WINDS HAVE AN EASTERLY COMPONENT ON ITS IMMEDIATE COOL SIDE. WHERE
STORMS DO DEVELOP THIS AFTERNOON...SEVERE HAIL/DAMAGING WINDS WILL
BE POSSIBLE...AND A BRIEF TORNADO CANNOT BE RULED OUT NEAR THE
OUTFLOW BOUNDARY GIVEN AN ENHANCED LOW-LEVEL SRH/VORTICITY-RICH
ENVIRONMENT.

..GUYER/MEAD.. 09/26/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...TSA...OUN...

LAT...LON   35509773 35999769 35539612 35299416 34729462 34779703
            35509773

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 26, 1:26 PM CDT	Mesoscale Discussion	SPC	Baxter, Boone, Clay, Cleburne, Craighead, Franklin and 17 more	94 min
Sep 26, 2:17 PM CDT	Severe Thunderstorm Watch	SPC	Crawford, Sebastian	8 hr
Sep 25, 7:29 PM CDT	Severe Thunderstorm Watch	SPC	Alfalfa, Beckham, Blaine, Caddo, Canadian, Comanche and 23 more	4 hr
Sep 25, 9:33 PM CDT	Mesoscale Discussion	SPC	Alfalfa, Blaine, Caddo, Canadian, Comanche, Cotton and 18 more	87 min
Sep 26, 1:50 PM CDT	Mesoscale Discussion	SPC	Cimarron, Texas	55 min
Sep 26, 3:59 PM CDT	Severe Thunderstorm Watch	SPC	Beaver, Cimarron, Texas	7 hr

Nearby

Mesoscale Discussions in Oklahoma, 2012 Mesoscale Discussions in Arkansas, 2012 Every 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.