Alert archive / Texas / Mesoscale Discussions in 2012
Mesoscale Discussion 240
The Storm Prediction Center issued this mesoscale discussion at Mar 11, 2012, 7:56 AM CDT for 21 counties in Texas. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Mar 11, 2012, 7:56 AM CDT (12:56 UTC)
- Expired
- Mar 11, 2012, 10:30 AM CDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
All 21 counties
Angelina County, TX, Brazoria County, TX, Chambers County, TX, Fort Bend County, TX, Galveston County, TX, Hardin County, TX, Harris County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Montgomery County, TX, Newton County, TX, Orange County, TX, Polk County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Trinity County, TX, Tyler County, TX, Walker County, TX, Waller County, TX
The radar
The Houston radar (KHGX), 85 km from the middle of the area, began a volume at 12:56 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
Lake Charles Mun, LA (KLCH), launched 12:00Z, 0.9 hours before the alert went out and 162 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
- 182 J/kg
- Mixed-layer CIN
- -71 J/kg
- Mixed-layer LCL
- 452 m above ground
- 0-6 km bulk shear
- 26 kt
- 0-1 km storm-relative helicity
- 246 m²/s²
- 0-3 km storm-relative helicity
- 294 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.1
The text
As transmitted, in the capitals the NWS used until 2016.
816
ACUS11 KWNS 111256
SWOMCD
SPC MCD 111256
LAZ000-TXZ000-111530-
MESOSCALE DISCUSSION 0240
NWS STORM PREDICTION CENTER NORMAN OK
0756 AM CDT SUN MAR 11 2012
AREAS AFFECTED...SOUTHEAST/EAST-CENTRAL TX TO FAR WESTERN LA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 111256Z - 111530Z
AN ISOLATED TORNADO/DAMAGING WIND POTENTIAL MAY DEVELOP/GRADUALLY
INCREASE THIS MORNING ACROSS PORTIONS OF SOUTHEAST INTO EAST-CENTRAL
TX/EVENTUALLY FAR WESTERN LA. INITIAL THINKING IS THAT A WATCH COULD
BE NEEDED AS EARLY AS MID/LATE MORNING ACROSS THE REGION.
PER LATEST SURFACE ANALYSIS...A MODIFIED GULF AIRMASS WITH
MIDDLE/UPPER 60S F SURFACE DEWPOINTS CONTINUES TO SLOWLY SPREAD
NORTHWARD ALONG THE UPPER TX COAST EARLY THIS MORNING. WITH ELEVATED
TSTMS ONGOING EARLY DAY ACROSS THE TX HILL COUNTRY...THE GRAZING
SOUTHERN INFLUENCE OF A CLOSED CYCLONE CENTERED/MOVING NORTHEASTWARD
OVER THE SOUTHERN HIGH PLAINS WILL LIKELY INTERACT WITH THIS
INCREASINGLY MOIST/POTENTIALLY UNSTABLE AIRMASS ACROSS SOUTHEAST
INTO EAST-CENTRAL TX/FAR WESTERN LA TODAY. AS SUCH...SURFACE BASED
TSTMS ARE LIKELY TO BECOME MORE PREVALENT WITHIN THE WARM/MOIST
SECTOR AHEAD OF A SLOW MOVING SURFACE TROUGH/WEAK FRONT...WITH
INCIPIENT SIGNS OF WEAK SUPERCELL STRUCTURES/INCREASING CG LIGHTNING
ALREADY NOTED NORTH OF HOUSTON VICINITY. ACCORDINGLY...THE LATEST
NUMERICAL GUIDANCE...INCLUDING CONVECTION ALLOWING MODELS SUCH AS
THE 00Z WRF-NMM AND SPC EXPERIMENTAL SSEO...IMPLY THAT STORMS SHOULD
GRADUALLY DEVELOP/MATURE INTO LATE MORNING/MIDDAY WITHIN A
PERSISTENT SSW-NNE CORRIDOR OF INCREASING MOIST/CONFLUENT LOW-LEVEL
FLOW. GIVEN THIS ANTICIPATED EVOLUTION/THERMODYNAMIC TRENDS...SHEAR
PROFILES COINCIDENT WITH THE ENTRANCE REGION OF A MODERATELY STRONG
SOUTHERLY LOW LEVEL JET WILL BE FAVORABLE FOR ISOLATED/EMBEDDED
SUPERCELL STRUCTURES CAPABLE OF A FEW TORNADOES ALONG WITH DAMAGING
WINDS/SOME HAIL.
..GUYER.. 03/11/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LCH...SHV...HGX...
LAT...LON 28849549 29729606 30889583 31629494 31499363 30699348
29689415 28849549SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Mar 11, 11:31 AM CDT | Mesoscale Discussion | SPC | Angelina, Chambers, Hardin, Jasper, Jefferson, Liberty and 9 more | 89 min |
| Mar 11, 11:55 AM CDT | Tornado Watch | SPC | Angelina, Chambers, Galveston, Gregg, Hardin, Harrison and 16 more | 7 hr |
| Mar 11, 2:47 PM CDT | Mesoscale Discussion | SPC | Jasper, Newton, Orange, Sabine | 118 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.