Alert archive / Texas / Mesoscale Discussions in 2016

Mesoscale Discussion 33

January 21, 201613 parishes in Louisiana; 18 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Jan 21, 2016, 10:59 AM CST for 13 parishes in Louisiana; 18 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jan 21, 2016, 10:59 AM CST (16:59 UTC)
Expired: Jan 21, 2016, 1:00 PM CST
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 31 counties

Acadia Parish, LA, Allen Parish, LA, Avoyelles Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Evangeline Parish, LA, Grant Parish, LA, Jefferson Davis Parish, LA, Natchitoches Parish, LA, Rapides Parish, LA, Sabine Parish, LA, Vernon Parish, LA, Winn Parish, LA, Angelina County, TX, Chambers County, TX, Hardin County, TX, Harris County, TX, Jasper County, TX, Jefferson County, TX, Liberty County, TX, Montgomery County, TX, Nacogdoches 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

The radar

The Lake Charles radar (KLCH), 99 km from the middle of the area, began a volume at 17:01 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, 5.0 hours before the alert went out and 101 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: 1051 J/kg
Mixed-layer CIN: -19 J/kg
Mixed-layer LCL: 548 m above ground
0-6 km bulk shear: 56 kt
0-1 km storm-relative helicity: 192 m²/s²
0-3 km storm-relative helicity: 215 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 4.2

Open this sounding in Storm Lab

The text

As transmitted.

650 
ACUS11 KWNS 211700
SWOMCD
SPC MCD 211659 
LAZ000-TXZ000-211900-

MESOSCALE DISCUSSION 0033
NWS STORM PREDICTION CENTER NORMAN OK
1059 AM CST THU JAN 21 2016

AREAS AFFECTED...SE TX...LA

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

VALID 211659Z - 211900Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...THE SEVERE THREAT ACROSS SE TX AND WRN TO CNTRL LA WILL
INCREASE OVER THE NEXT FEW HOURS. TORNADOES...ISOLATED LARGE HAIL
AND WIND DAMAGE WILL BE POSSIBLE WITH THE STRONGER STORMS. A TORNADO
WATCH WILL LIKELY BE NEEDED ACROSS THE REGION LATE THIS MORNING.

DISCUSSION...LATEST SFC ANALYSIS SHOWS A 1012 MB SFC LOW TO THE
NORTH OF HOUSTON WITH A TRAILING COLD FRONT EXTENDING SWWD FROM THE
LOW. A QUASI-STATIONARY FRONT EXTENDS EWD FROM THE LOW ACROSS CNTRL
LA WITH THE WARM SECTOR LOCATED IN SE TX AND SCNTRL LA. SFC
DEWPOINTS ACROSS THE WARM SECTOR RANGE FROM THE UPPER 50S F IN CNTRL
LA TO THE MID 60S F NEAR THE LA COAST. SFC TEMPS HAVE WARMED INTO
THE 60S F ACROSS THE WARM SECTOR HELPING TO INCREASE INSTABILITY.
MLCAPE VALUES ARE ESTIMATED TO BE OVER 1000 J/KG ACROSS PARTS OF SW
LA AND ACROSS MOST OF SE TX. THUNDERSTORMS ARE DEVELOPING ALONG THE
FRONT AND ALONG A CONFLUENCE ZONE AHEAD OF THE FRONT. THIS ACTIVITY
SHOULD GRADUALLY INCREASE IN COVERAGE OVER THE NEXT FEW HOURS AS THE
SFC LOW DEEPENS AND THE EXIT REGION OF A MID-LEVEL JET OVERSPREADS
THE REGION. THE MID-LEVEL JET IS CONTRIBUTING TO STRONG DEEP-LAYER
SHEAR PROFILES WITH THE LAKE CHARLES WSR-88D VWP SHOWING 50 TO 55 KT
OF 0-6 KM SHEAR. THIS COMBINED WITH 0-3 KM STORM RELATIVE HELICITIES
NEAR 250 M2/S2 SHOULD BE FAVORABLE FOR STORM ROTATION AND POSSIBLY
TORNADOES. STEEP MID-LEVEL LAPSE RATES AROUND 7.5 C/KM SHOULD ALSO
BE FAVORABLE FOR ISOLATED LARGE HAIL. WIND DAMAGE MAY ALSO OCCUR
WITH ROTATING STORMS OR SHORT-LINE SEGMENTS.

..BROYLES/THOMPSON.. 01/21/2016

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...JAN...LCH...SHV...HGX...

LAT...LON   31599485 30869557 30149578 29539540 29599430 30009265
            30599199 31269192 32059253 31599485

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 21, 4:40 AM CST	Mesoscale Discussion	SPC	Allen, Beauregard, Bienville, Caddo, De Soto, Grant and 8 more	95 min
Jan 21, 11:48 AM CST	Tornado Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Caldwell and 12 more	5 hr
Jan 21, 1:44 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 29 more	2 hr
Jan 21, 2:14 PM CST	Tornado Watch	SPC	Ascension, Assumption, Catahoula, Concordia, East Baton Rouge, East Feliciana and 23 more	6 hr
Jan 21, 4:57 PM CST	Mesoscale Discussion	SPC	East Feliciana, Saint Helena	63 min

Nearby

Mesoscale Discussions in Texas, 2016 Mesoscale Discussions in Louisiana, 2016 Every mesoscale discussion in 2016

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.