Alert archive / Texas / Mesoscale Discussions in 2012
Mesoscale Discussion 795
The Storm Prediction Center issued this mesoscale discussion at May 12, 2012, 4:20 PM CDT for 4 counties in Texas. It was in force for 55 min.
The area
The outline as issued.
The facts
- Issued
- May 12, 2012, 4:20 PM CDT (21:20 UTC)
- Expired
- May 12, 2012, 5:15 PM CDT
- In force
- 55 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 5%
Counties Brooks County, TX, Cameron County, TX, Hidalgo County, TX, Willacy County, TX
The radar
The Brownsville radar (KBRO), 89 km from the middle of the area, began a volume at 21:22 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
Brownsville Intl, TX (KBRO), launched 12:00Z, 9.3 hours before the alert went out and 92 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
- 3455 J/kg
- Mixed-layer CIN
- 0 J/kg
- Mixed-layer LCL
- 477 m above ground
- 0-6 km bulk shear
- 32 kt
- 0-1 km storm-relative helicity
- 45 m²/s²
- 0-3 km storm-relative helicity
- 9 m²/s²
- Significant tornado parameter
- 0.3
- Supercell composite
- 1.5
The text
As transmitted, in the capitals the NWS used until 2016.
215
ACUS11 KWNS 122120
SWOMCD
SPC MCD 122120
TXZ000-122215-
MESOSCALE DISCUSSION 0795
NWS STORM PREDICTION CENTER NORMAN OK
0420 PM CDT SAT MAY 12 2012
AREAS AFFECTED...A SMALL PART OF DEEP SOUTH TX
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 122120Z - 122215Z
PROBABILITY OF WATCH ISSUANCE...5 PERCENT
SUMMARY...AN ISOLATED SVR THREAT WILL PERSIST INTO EARLY EVENING.
THE SPARSE COVERAGE AND BRIEF DURATION OF THE THREAT WILL PRECLUDE
THE ISSUANCE OF A WW.
DISCUSSION...ISOLATED CONVECTION HAS DEVELOPED OVER PARTS OF WILLACY
COUNTY OWING TO LOW-LEVEL ASCENT ATTENDANT TO THE GULF BREEZE
CIRCULATION THAT HAS BEEN SHIFTING INLAND PER CU LINE EVIDENT IN
VISIBLE SATELLITE IMAGERY. WITH BROWNSVILLE VWP DATA SUGGESTING
SFC-6-KM BULK SHEAR OF 33 KT...CONVECTION HAS EXHIBITED SOME
ORGANIZATION MAINLY CHARACTERIZED BY A MULTICELLULAR MODE. GIVEN
STEEP LOW-LEVEL LAPSE RATES AND APPRECIABLE BUOYANCY NEAR AND WEST
OF THE GULF BREEZE...OWING TO TEMPERATURES IN THE LOWER
90S...NOTABLE WWD/SWWD PROPAGATION HAS BEEN NOTED AS CONVECTION
REGENERATES OVER THE WRN/SWRN FLANKS OF STORM-INDUCED COLD POOLS. AS
SUCH...CONVECTION MAY APPROACH THE RIO GRANDE VALLEY AND BE
ASSOCIATED WITH A DMGG WIND THREAT GIVEN DCAPE VALUES IN EXCESS OF
1200 J/KG...ALONG WITH A THREAT FOR MARGINALLY SVR HAIL. AS
NOCTURNAL STABILIZATION OCCURS BY EARLY EVENING...THE THREAT WILL
SUBSIDE IN THE ABSENCE OF STRONGER FORCING FOR ASCENT.
..COHEN/WEISS.. 05/12/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...BRO...
LAT...LON 26269876 26669872 27059822 27139773 26749753 26069733
25939761 26009805 26269876SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 11, 7:28 PM CDT | Mesoscale Discussion | SPC | Austin, Brazoria, Chambers, Fort Bend, Hardin, Harris and 10 more | 32 min |
| May 11, 7:36 PM CDT | Tornado Watch | SPC | Brazoria, Chambers, Fort Bend, Galveston, Hardin, Harris and 11 more | 6 hr |
| May 11, 10:31 PM CDT | Mesoscale Discussion | SPC | Brazoria, Chambers, Fort Bend, Galveston, Hardin, Harris and 11 more | 89 min |
| May 12, 1:40 AM CDT | Mesoscale Discussion | SPC | Brazoria, Chambers, Fort Bend, Galveston, Hardin, Harris and 11 more | 65 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.