Alert archive / Texas / Mesoscale Discussions in 2012
Mesoscale Discussion 2117
The Storm Prediction Center issued this mesoscale discussion at Nov 11, 2012, 10:12 AM CST for 4 counties in Arkansas; McCurtain County, Oklahoma; 19 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Nov 11, 2012, 10:12 AM CST (16:12 UTC)
- Expired
- Nov 11, 2012, 12:15 PM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 60%
All 24 counties
Howard County, AR, Little River County, AR, Pike County, AR, Sevier County, AR, McCurtain County, OK, Anderson County, TX, Bowie County, TX, Camp County, TX, Cass County, TX, Cherokee County, TX, Franklin County, TX, Freestone County, TX, Gregg County, TX, Henderson County, TX, Hopkins County, TX, Leon County, TX, Morris County, TX, Rains County, TX, Red River County, TX, Smith County, TX, Titus County, TX, Upshur County, TX, Van Zandt County, TX, Wood County, TX
The radar
The Shreveport radar (KSHV), 127 km from the middle of the area, began a volume at 16:16 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
Shreveport, LA (KSHV), launched 12:00Z, 4.2 hours before the alert went out and 133 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
- 14 J/kg
- Mixed-layer CIN
- -571 J/kg
- Mixed-layer LCL
- 641 m above ground
- 0-6 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- 389 m²/s²
- 0-3 km storm-relative helicity
- 482 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
704
ACUS11 KWNS 111613
SWOMCD
SPC MCD 111612
ARZ000-TXZ000-OKZ000-111815-
MESOSCALE DISCUSSION 2117
NWS STORM PREDICTION CENTER NORMAN OK
1012 AM CST SUN NOV 11 2012
AREAS AFFECTED...NERN TX...SWRN AR...FAR SERN OK
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 111612Z - 111815Z
PROBABILITY OF WATCH ISSUANCE...60 PERCENT
SUMMARY...N/S-ORIENTED BAND OF PRE-FRONTAL TSTMS MAY ACQUIRE
TRANSIENT SUPERCELL STRUCTURES BY MIDDAY. ALTHOUGH BUOYANCY IS
WEAK...STRONG LOW-LEVEL SHEAR SHOULD PROMOTE A LOW-END RISK FOR
TORNADOES AND DAMAGING WINDS.
DISCUSSION...N/S-ORIENTED BAND OF TSTMS...ROUGHLY FROM 25 SW PRX TO
50 S CRS AT 16Z...HAS INITIATED IN THE PAST HALF HOUR. INTERPOLATED
PROFILER/VWP DATA INDICATE FAVORABLE 0-1 KM SHEAR FOR LOW-LEVEL
ROTATION. HOWEVER...WEAKNESS IN THE HODOGRAPH AROUND 2-3 KM AGL
/ESPECIALLY WITH SRN EXTENT/ SHOULD LIMIT SUSTAINABILITY OF
SUPERCELL UPDRAFTS WITHIN A WEAKLY UNSTABLE AIR MASS. ALTHOUGH
SURFACE HEATING IS BEING RETARDED BY WIDESPREAD CLOUD COVER...THERE
IS CONCERN FOR A LOW-END TORNADO/DAMAGING WIND RISK THAT MAY BE
SUFFICIENT FOR A WW ISSUANCE BY MIDDAY.
..GRAMS/WEISS.. 11/11/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LZK...SHV...TSA...HGX...FWD...
LAT...LON 33329573 33969513 34419467 34459413 34319372 34229361
33689384 32109479 31369539 31229585 31279625 31569638
33329573SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Nov 11, 12:53 PM CST | Tornado Watch | SPC | Clark, Columbia, Dallas, Garland, Hempstead, Hot Spring and 11 more | 6 hr |
| Nov 11, 2:47 PM CST | Mesoscale Discussion | SPC | Calhoun, Clark, Cleveland, Columbia, Dallas, Grant and 10 more | 88 min |
| Nov 11, 5:49 AM CST | Mesoscale Discussion | SPC | Cherokee, Craig, Creek, Delaware, McIntosh, Mayes and 9 more | 86 min |
Nearby
Mesoscale Discussions in Texas, 2012Mesoscale Discussions in Arkansas, 2012Mesoscale Discussions in Oklahoma, 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.