Alert archive / Texas / Mesoscale Discussions in 2016

Mesoscale Discussion 412

April 18, 201616 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 18, 2016, 12:57 PM CDT for 16 counties in Texas. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Apr 18, 2016, 12:57 PM CDT (17:57 UTC)
Expired: Apr 18, 2016, 3:00 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 40%

Counties Brooks County, TX, Cameron County, TX, Dimmit County, TX, Duval County, TX, Hidalgo County, TX, Jim Hogg County, TX, Jim Wells County, TX, Kenedy County, TX, Kleberg County, TX, La Salle County, TX, McMullen County, TX, Nueces County, TX, Starr County, TX, Webb County, TX, Willacy County, TX, Zapata County, TX

The radar

The Corpus Christi radar (KCRP), 127 km from the middle of the area, began a volume at 17:58 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.

Severe Thunderstorm Watch 97Apr 18, 3:20 PM CDT

The nearest sounding before it

Corpus Christi, TX (KCRP), launched 12:00Z, 6.0 hours before the alert went out and 141 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: 2403 J/kg
Mixed-layer CIN: -24 J/kg
Mixed-layer LCL: 614 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 60 m²/s²
0-3 km storm-relative helicity: 186 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 3.2

Open this sounding in Storm Lab

The text

As transmitted.

484 
ACUS11 KWNS 181757
SWOMCD
SPC MCD 181757 
TXZ000-182000-

MESOSCALE DISCUSSION 0412
NWS STORM PREDICTION CENTER NORMAN OK
1257 PM CDT MON APR 18 2016

AREAS AFFECTED...SRN TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 181757Z - 182000Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...STORMS WILL INCREASE IN COVERAGE WITH LARGE HAIL THE
LOCALIZED DAMAGING WIND GUSTS POSSIBLE.

DISCUSSION...TEMPERATURES CONTINUE TO RISE WELL INTO THE 80S F
ACROSS SRN TX AHEAD OF A SWD-MOVING OUTFLOW BOUNDARY WITH STRONG
INSTABILITY DEVELOPING. ELY LOW-LEVEL FLOW BENEATH MODEST WESTERLIES
ALOFT WILL FAVOR SEWD-MOVING SUPERCELLS...AND PERHAPS BOWING STORMS
CAPABLE OF LARGE HAIL THEN DAMAGING WINDS.

A RECENT INCREASE OF STORM ACTIVITY WAS NOTED ALONG WRN PORTIONS OF
THE OUTFLOW BOUNDARY NEAR THE RIO GRANDE. SOME OF THE NRN CELLS HAVE
SINCE BECOME UNDERCUT BUT THE SRN CELL APPROACHING FAR NWRN WEBB
COUNTY APPEARS TO BE MAINTAINING ITSELF VIA ESEWD PROPAGATION ALONG
THE BOUNDARY. THIS CELL MAY BECOME SEVERE WITH A HAIL AND WIND
THREAT IF IT CAN CONTINUE TO STAY CLOSE TO THE BOUNDARY AND AS
TEMPERATURES CONTINUE TO WARM UPSTREAM.

OTHER CELLS ARE EXPECTED TO DEVELOP NEAR THE BOUNDARY...WITH STILL
OTHERS FORMING OVER MEXICO AND THREATENING THE LOWER RIVER VALLEY
LATER TODAY.

..JEWELL/HART.. 04/18/2016

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

ATTN...WFO...CRP...EWX...BRO...

LAT...LON   28530043 28629947 28389848 27769706 27419721 27169729
            26379717 25709704 26069872 26329922 27019950 27489979
            27880014 28530043

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 17, 8:21 PM CDT	Mesoscale Discussion	SPC	Starr, Zapata	84 min
Apr 18, 12:02 AM CDT	Mesoscale Discussion	SPC	Harris, Liberty, Montgomery, San Jacinto	118 min
Apr 18, 4:29 AM CDT	Mesoscale Discussion	SPC	Kinney, Medina, Uvalde	61 min
Apr 18, 5:10 AM CDT	Mesoscale Discussion	SPC	Fort Bend, Harris, Liberty	95 min
Apr 18, 3:21 PM CDT	Severe Thunderstorm Watch	SPC	Brooks, Cameron, Duval, Hidalgo, Jim Hogg, Jim Wells and 7 more	8 hr
Apr 18, 5:54 PM CDT	Mesoscale Discussion	SPC	Brooks, Cameron, Dimmit, Duval, Hidalgo, Jim Hogg and 10 more	2 hr

Nearby

Mesoscale Discussions in Texas, 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.