Alert archive / Texas / Mesoscale Discussions in 2012
Mesoscale Discussion 2180
The Storm Prediction Center issued this mesoscale discussion at Dec 19, 2012, 9:00 PM CST for 25 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 19, 2012, 9:00 PM CST (03:00 UTC)
- Expired
- Dec 19, 2012, 11:00 PM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
All 25 counties
Anderson County, TX, Camp County, TX, Cherokee County, TX, Dallas County, TX, Ellis County, TX, Falls County, TX, Freestone County, TX, Gregg County, TX, Henderson County, TX, Hill County, TX, Hopkins County, TX, Houston County, TX, Hunt County, TX, Kaufman County, TX, Leon County, TX, Limestone County, TX, McLennan County, TX, Navarro County, TX, Rains County, TX, Rockwall County, TX, Rusk County, TX, Smith County, TX, Upshur County, TX, Van Zandt County, TX, Wood County, TX
The radar
The Dallas/Ft Worth radar (KFWS), 100 km from the middle of the area, began a volume at 03:02 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
Fort Worth, TX (KFWD), launched 00:00Z, 3.0 hours before the alert went out and 117 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
- 211 J/kg
- Mixed-layer CIN
- -28 J/kg
- Mixed-layer LCL
- 1492 m above ground
- 0-6 km bulk shear
- 70 kt
- 0-1 km storm-relative helicity
- 240 m²/s²
- 0-3 km storm-relative helicity
- 233 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 5.2
The text
As transmitted, in the capitals the NWS used until 2016.
125 ACUS11 KWNS 200300 SWOMCD SPC MCD 200300 TXZ000-200500- MESOSCALE DISCUSSION 2180 NWS STORM PREDICTION CENTER NORMAN OK 0900 PM CST WED DEC 19 2012 AREAS AFFECTED...NORTH-CENTRAL/NORTHEAST TX CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE VALID 200300Z - 200500Z PROBABILITY OF WATCH ISSUANCE...40 PERCENT SUMMARY...TSTMS SHOULD CONTINUE TO INCREASE IN COVERAGE/INTENSITY ACROSS PORTIONS OF NORTH-CENTRAL/NORTHEAST TX THROUGH LATE EVENING AND INTO THE OVERNIGHT. THE EXTENT OF THE SEVERE THREAT IS A BIT UNCERTAIN...BUT ISOLATED DAMAGING WINDS/HAIL WILL BE POSSIBLE WITH THE STRONGEST TSTMS. DISCUSSION...TO THE SOUTH OF TORNADO WATCH 686...TSTMS HAVE STEADILY INCREASED SINCE 0215Z FROM NEAR THE RED RIVER TO THE DFW METRO VICINITY AS OF 0245Z. THIS IS OCCURRING INITIALLY NEAR A DRY LINE/PRE-FRONTAL THROUGH...WITH TSTM COVERAGE LIKELY TO ONLY INCREASE THE REMAINDER OF THE NIGHT AS THE COLD FRONT ACCELERATES/OVERTAKES THE PRE-FRONTAL BOUNDARY. LOW-LEVEL WINDS HAVE BEEN NOTED TO VEER WITHIN THE LOWEST FEW KM AHEAD OF THE SURFACE BOUNDARY PER SURFACE OBS AND PROFILER/WSR-88D VWP DATA. THIS MAY BE INDICATIVE OF A MORE MODEST MASS RESPONSE ON THE SOUTHERN PERIPHERY OF THE PLAINS CYCLONE. THIS MAY INFLUENCE TSTM COVERAGE/VIGOR TO A DEGREE...SUCH THAT EXTENT OF THE SEVERE THREAT TONIGHT IS A BIT QUESTIONABLE. THAT SAID...ISOLATED SEVERE TSTMS WILL BE POSSIBLE WHERE STORMS DO MATURE TONIGHT...GIVEN ADEQUATE INSTABILITY AND VERY STRONG DEEP LAYER SHEAR /70 KT 0-6 KM PER 00Z FORT WORTH SOUNDING/. WHILE AN ISOLATED TORNADO AND/OR HAIL CANNOT BE RULED OUT...INITIATION/CONVECTIVE MODE SUGGEST THAT DAMAGING WINDS WOULD BE THE PRIMARY RISK. CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED FOR A POSSIBLE WATCH. ..GUYER/WEISS.. 12/20/2012 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...SHV...HGX...FWD... LAT...LON 31139791 32919685 33289624 32969438 31039522 31139791
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 19, 7:07 PM CST | Mesoscale Discussion | SPC | Bowie, Camp, Cass, Collin, Dallas, Delta and 15 more | 53 min |
| Dec 19, 7:36 PM CST | Tornado Watch | SPC | Bowie, Fannin, Grayson, Lamar, Red River | 6 hr |
| Dec 19, 9:56 PM CST | Severe Thunderstorm Watch | SPC | Anderson, Camp, Cass, Cherokee, Delta, Franklin and 20 more | 5 hr |
| Dec 19, 10:22 PM CST | Mesoscale Discussion | SPC | Lamar | 83 min |
| Dec 19, 11:55 PM CST | Mesoscale Discussion | SPC | Anderson, Angelina, Cherokee, Gregg, Harrison, Houston and 18 more | 95 min |
| Dec 20, 1:07 AM CST | Severe Thunderstorm Watch | SPC | Angelina, Jasper, Newton, Sabine, San Augustine, Tyler | 5 hr |
Nearby
Mesoscale Discussions in Texas, 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.