Alert archive / Louisiana / Mesoscale Discussions in 2019

Mesoscale Discussion 607

May 9, 20195 parishes in Louisiana; 4 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at May 9, 2019, 11:23 PM CDT for 5 parishes in Louisiana; 4 counties in Texas. It was in force for 67 min.

The area

The outline as issued.

The facts

Issued: May 9, 2019, 11:23 PM CDT (04:23 UTC)
Expired: May 10, 2019, 12:30 AM CDT
In force: 67 min
Issued by: the Storm Prediction Center

Counties Acadia Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, Jefferson Davis Parish, LA, Vermilion Parish, LA, Chambers County, TX, Hardin County, TX, Jefferson County, TX, Orange County, TX

The radar

The Lake Charles radar (KLCH), 63 km from the middle of the area, began a volume at 04:28 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

Lake Charles Mun, LA (KLCH), launched 00:00Z, 4.4 hours before the alert went out and 64 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 409 J/kg
Mixed-layer CIN: -201 J/kg
Mixed-layer LCL: 819 m above ground
0-6 km bulk shear: 57 kt
0-1 km storm-relative helicity: 29 m²/s²
0-3 km storm-relative helicity: 86 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.8

Open this sounding in Storm Lab

The text

As transmitted.

103 
ACUS11 KWNS 100424
SWOMCD
SPC MCD 100423 
LAZ000-TXZ000-100530-

Mesoscale Discussion 0607
NWS Storm Prediction Center Norman OK
1123 PM CDT Thu May 09 2019

Areas affected...Upper Texas Coast to southwest LA

Concerning...Severe Thunderstorm Watch 159...161...

Valid 100423Z - 100530Z

The severe weather threat for Severe Thunderstorm Watch 159, 161
continues.

SUMMARY...A locally increased threat for a couple of tornadoes will
exist the next couple of hours across far southeast TX into
southwest LA. In addition to this threat, a continued threat for
damaging winds and hail will persist during the overnight hours.

DISCUSSION...A couple of discrete supercells were located over far
southwest LA in the vicinity of an outflow boundary late this
evening. Large hail is possible with both of these cells in addition
to damaging winds. The latest VWP data from KLCH indicated increased
low level southeasterly flow compared to earlier this evening.
Furthermore, an intense embedded supercell further to the west was
exiting Galveston Bay and entering Chambers County TX. This cell
showed moderate low level rotation over the past 20 minutes, and WFO
HOU recently issued a tornado warning for this cell. Given the
presence of the surface boundary across this region and
strengthening low level easterly flow within a very moist and
unstable airmass, the threat for a couple of tornadoes appears to be
locally increased for a few hours late this evening. This threat
will accompany any discrete cells as well as mesovortices within the
developing bow over far southeast TX.

..Leitman.. 05/10/2019

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...LCH...HGX...

LAT...LON   30379461 30589362 30349237 29699208 29159243 29239391
            29329476 29489481 30029474 30379461

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 9, 9:49 PM CDT	Mesoscale Discussion	SPC	Acadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 7 more	86 min
May 9, 10:36 PM CDT	Severe Thunderstorm Watch	SPC	Allen, Beauregard, Calcasieu, Cameron, Jefferson Davis, Vermilion	4 hr
May 10, 1:35 AM CDT	Mesoscale Discussion	SPC	Calcasieu, Cameron, Jefferson Davis	85 min
May 9, 8:26 PM CDT	Mesoscale Discussion	SPC	Aransas, Atascosa, Austin, Bee, Brazoria, Calhoun and 31 more	94 min
May 9, 9:44 PM CDT	Severe Thunderstorm Watch	SPC	Aransas, Brooks, Calhoun, Duval, Jim Hogg, Jim Wells and 7 more	7 hr

Nearby

Mesoscale Discussions in Louisiana, 2019 Mesoscale Discussions in Texas, 2019 Every mesoscale discussion in 2019

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.