Alert archive / Texas / Mesoscale Discussions in 2012
Mesoscale Discussion 2131
The Storm Prediction Center issued this mesoscale discussion at Dec 4, 2012, 1:08 PM CST for 26 counties in Texas. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 4, 2012, 1:08 PM CST (19:08 UTC)
- Expired
- Dec 4, 2012, 3:15 PM CST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 40%
All 26 counties
Aransas County, TX, Austin County, TX, Bee County, TX, Brazoria County, TX, Brooks County, TX, Calhoun County, TX, Colorado County, TX, DeWitt County, TX, Duval County, TX, Fort Bend County, TX, Galveston County, TX, Goliad County, TX, Harris County, TX, Jackson County, TX, Jim Wells County, TX, Karnes County, TX, Kleberg County, TX, Lavaca County, TX, Live Oak County, TX, Matagorda County, TX, McMullen County, TX, Nueces County, TX, Refugio County, TX, San Patricio County, TX, Victoria County, TX, Wharton County, TX
The radar
The Corpus Christi radar (KCRP), 70 km from the middle of the area, began a volume at 19:11 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 nearest sounding before it
Corpus Christi, TX (KCRP), launched 12:00Z, 7.1 hours before the alert went out and 68 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
- 1399 J/kg
- Mixed-layer CIN
- -90 J/kg
- Mixed-layer LCL
- 715 m above ground
- 0-6 km bulk shear
- 25 kt
- 0-1 km storm-relative helicity
- 76 m²/s²
- 0-3 km storm-relative helicity
- 68 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 2.6
The text
As transmitted, in the capitals the NWS used until 2016.
217
ACUS11 KWNS 041909
SWOMCD
SPC MCD 041908
TXZ000-042115-
MESOSCALE DISCUSSION 2131
NWS STORM PREDICTION CENTER NORMAN OK
0108 PM CST TUE DEC 04 2012
AREAS AFFECTED...TX COASTAL PLAIN
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 041908Z - 042115Z
PROBABILITY OF WATCH ISSUANCE...40 PERCENT
SUMMARY...A SMALL SEVERE TSTM WATCH MAY BE CONSIDERED FOR PARTS OF
THE TX COASTAL PLAIN THIS AFTERNOON-EVENING. ISOLD LARGE HAIL AND A
FEW INSTANCES OF STRONG-SEVERE WIND GUSTS ARE POSSIBLE THRU THE
EARLY EVENING.
DISCUSSION...TRENDS IN VISIBLE SATELLITE IMAGERY SHOW A SWELLING CU
FIELD INVOF A PRE-FRONTAL WINDSHIFT AND OVER A WARM SECTOR LOCATED
OVER THE TX COASTAL PLAIN. SURFACE TEMPS HAVE WARMED INTO THE LOWER
80S AMIDST AN ADEQUATELY MOIST/DESTABILIZING AIRMASS. A MID-LEVEL
SPEED MAX IS CONTINUING TO APPROACH THE REGION FROM THE CONCHO RIVER
VALLEY/EDWARDS PLATEAU REGION. UPWARD VERTICAL MOTION ASSOCIATED
WITH THE UPPER FEATURE...COMBINED WITH WEAK LOW LEVEL CONFLUENCE
ALONG THE PREFRONTAL BOUNDARY...AND DIABATIC HEATING WILL ACT TO
FURTHER WEAKEN THE CAP SAMPLED BY THE 12Z CRP RAOB. THE CAP HAS
ALREADY ERODED FROM MATAGORDA BAY NEWD TO THE SABINE RIVER...WITH
SCTD STORMS /OCCASIONAL PULSATING SEVERE UPDRAFT/ EXPECTED TO LEAD
TO SUBSTANTIAL CONVECTIVE OVERTURNING OVER THE NEXT FEW
HRS...THEREBY LESSENING THE SEVERE RISK IN THIS REGION. FARTHER
SSW...MORE SPARSE CONVECTIVE COVERAGE --LIKELY DELAYED UNTIL
MID-LATE AFTERNOON-- IS EXPECTED. UPWARDS OF 40 KT DEEP SHEAR AND A
MODERATELY UNSTABLE AIRMASS /1500 J/KG MLCAPE/ WILL SUPPORT
ORGANIZED STORM STRUCTURES CAPABLE OF ISOLD LARGE HAIL/DMGG WIND
GUSTS.
..SMITH/MEAD.. 12/04/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...HGX...CRP...EWX...BRO...
LAT...LON 27199742 26789801 27619907 28629874 29919674 30099507
29359469 28019688 27199742SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 4, 11:09 AM CST | Mesoscale Discussion | SPC | Angelina, Chambers, Hardin, Jasper, Jefferson, Liberty and 8 more | 96 min |
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.