Alert archive / Texas / Mesoscale Discussions in 2015

Mesoscale Discussion 2011

December 13, 2015Chambers County, Galveston County, Texas

The Storm Prediction Center issued this mesoscale discussion at Dec 13, 2015, 7:17 AM CST for Chambers County, Galveston County, Texas. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued: Dec 13, 2015, 7:17 AM CST (13:17 UTC)
Expired: Dec 13, 2015, 8:45 AM CST
In force: 88 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Chambers County, TX, Galveston County, TX

The radar

The Houston radar (KHGX), 30 km from the middle of the area, began a volume at 13:20 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 12:00Z, 1.3 hours before the alert went out and 170 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: 341 J/kg
Mixed-layer CIN: -5 J/kg
Mixed-layer LCL: 506 m above ground
0-6 km bulk shear: 63 kt
0-1 km storm-relative helicity: 346 m²/s²
0-3 km storm-relative helicity: 408 m²/s²
Significant tornado parameter: 0.8
Supercell composite: 5.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

083 
ACUS11 KWNS 131318
SWOMCD
SPC MCD 131317 
TXZ000-131445-

MESOSCALE DISCUSSION 2011
NWS STORM PREDICTION CENTER NORMAN OK
0717 AM CST SUN DEC 13 2015

AREAS AFFECTED...UPPER TX COAST

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 131317Z - 131445Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...A LOCALIZED WIND DAMAGE/WEAK TORNADO RISK MAY DEVELOP NEAR
GALVESTON BAY OVER THE NEXT 1-2 HOURS.  LIMITED SPATIAL
COVERAGE/MAGNITUDE OF THE THREAT WILL LIKELY PRECLUDE A WATCH
ISSUANCE.

DISCUSSION...LATEST TRENDS IN KHGX RADAR IMAGERY SHOW A FEW WEAK
ROTATIONAL COUPLETS S OF GALVESTON ISLAND MOVING NNEWD AND ARE
EXTRAPOLATED TO REACH THE COAST OVER THE NEXT 1-2 HOURS.  WHILE THIS
CONVECTION IS OCCURRING LARGELY IN THE ABSENCE OF DETECTED
LIGHTNING...THE VERY STRONG AND VEERING LOW-LEVEL WIND PROFILE
COUPLED WITH SUFFICIENT BUOYANCY IS SUPPORTING UPDRAFT ROTATION. 
THE MAIN THREATS WITH ANY SHALLOW SUPERCELL WOULD BE A LOCALIZED
WIND DAMAGE AND WEAK/BRIEF TORNADO THREAT BEFORE THE COLD FRONT
UNDERCUTS THE STORM ACTIVITY LATER THIS MORNING.

..SMITH/MEAD.. 12/13/2015

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

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

LAT...LON   28989509 29569493 29869469 29949442 29679435 28959483
            28989509

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 12, 6:09 PM CST	Mesoscale Discussion	SPC	Anderson, Bowie, Brazos, Camp, Cass, Cherokee and 34 more	96 min
Dec 12, 9:14 PM CST	Mesoscale Discussion	SPC	Archer, Baylor, Brown, Callahan, Childress, Coleman and 32 more	2 hr
Dec 12, 11:40 PM CST	Mesoscale Discussion	SPC	Archer, Bandera, Bexar, Blanco, Bosque, Burnet and 27 more	35 min
Dec 13, 9:18 AM CST	Mesoscale Discussion	SPC	Dallam, Hansford, Hartley, Hutchinson, Moore, Ochiltree and 1 more	6 hr

Nearby

Mesoscale Discussions in Texas, 2015 Every mesoscale discussion in 2015

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.