Alert archive / Texas / Special Weather Statements in 2017
Special Weather Statement, NWS Austin/San Antonio, TX
NWS Austin/San Antonio, TX issued this special weather statement at Aug 4, 2017, 6:58 PM CDT for Lavaca County, Texas. It was in force for 32 min. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Aug 4, 2017, 6:58 PM CDT (23:58 UTC)
- Expired
- Aug 4, 2017, 7:30 PM CDT
- In force
- 32 min
- Issued by
- NWS Austin/San Antonio, TX
County Lavaca County, TX
The radar
The Austin/San Antonio radar (KEWX), 124 km from the middle of the area, began a volume at 00:00 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
Brownsville Intl, TX (KBRO), launched 12:00Z, 12.0 hours before the alert went out and 361 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
- 1992 J/kg
- Mixed-layer CIN
- -18 J/kg
- Mixed-layer LCL
- 771 m above ground
- 0-6 km bulk shear
- 6 kt
- 0-1 km storm-relative helicity
- -51 m²/s²
- 0-3 km storm-relative helicity
- -38 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
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</html>What forecasters said that day
The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Austin/San Antonio, TX wrote its last area forecast discussion before this special weather statement went out at Aug 4, 6:41 PM CDT, 17 minutes earlier.
Area forecast discussion, Aug 4, 6:41 PM CDT, 17 minutes before
Area Forecast Discussion National Weather Service Austin/San Antonio TX 641 PM CDT Fri Aug 4 2017 .AVIATION DISCUSSION...FOR 00Z TAF PERIOD... Majority of convection has dissipated at TAF issuance. Should remain VFR throughout the evening and most of the overnight hours. Some MVFR development looks possible for KSAT/KSSF tomorrow morning but should stay clear of KAUS based off model projections. Do expect -TSRA development in the afternoon with best shot at impacts at KAUS but not enough confidence in a direct terminal impact to include a prevailing line for this. Thus opted for VCTS as many isolated cells will likely begin developing shortly after 18Z. KSAT/KSSF may see some nearby convection from the east in the late afternoon. KDRT expected to prevail VFR throughout the period. && .PREV DISCUSSION... /ISSUED 304 PM CDT Fri Aug 4 2017/ SHORT TERM (Tonight through Saturday)... Main short-term highlight will center on the isolated/scattered showers this afternoon and again tomorrow along with the elevated heat indices of 100-107F across the region. Water vapor imagery and RAP H5 output indicate northwest flow across the region with a weak shortwave trough across central Texas this afternoon. Despite this axis of slightly enhanced divergence due to the shortwave trough, wind shear and speeds remain very light aloft. As such, most of the isolated shower activity is being driven by instability alone along with outflow boundary collisions. ML CAPE values range from 500-1250 J/Kg this afternoon across the region and this is keeping coverage and intensity at bay. Most of the showers have struggled to even produce lightning so far this afternoon. With the right collisions from storm-induced outflow boundaries due to dry sub-cloud environments (inverted V soundings), a few thunderstorms could occur through the early evening hours before activity dissipates out by 9-10pm. By Saturday, the current shortwave trough flattens out to more zonal flow over much of the region. However, another compact but weak disturbance over the Texas Big Bend region will help generate some additional shower and thunderstorm activity tomorrow. This feature, coupled with the sea-breeze and diurnal instability will foster isolated to scattered showers once again. Overall coverage will be in the 20-40% range for most of the area. Some enhancement of greater coverage could occur across the Coastal Plains due to the sea- breeze. LONG TERM (Sunday through Friday)... Increasing rain chances appear on the horizon for late weekend and into the early next week where 40-60% chances are currently forecast. Pockets of localized heavy rain could also be possible during this time as well. Scattered showers look to occur through much of mid to late week as well, mainly during the afternoons. The weak disturbance mentioned over the Big Bend on Saturday will move slowly eastward on Sunday. With day-time heating, at least scattered showers are expected across a good portion of the region Sunday. At the same time, a potential boundary will shift south across central OK. With general troughing and instability, a stronger convective complex and reinforced outflow could then reach into central Texas. The combination of the weak convective outflow plus the disturbance and weak instability should support the start of a wetter period. For Monday and Tuesday, much of central Texas will be located in a weakness and light shear axis region as PWATS increase to above 2 inches. These factors combined should allow for semi-organized showers and storms that could produce heavy rain at times. The greatest likelihood of higher totals currently appears to be over the Hill Country and northern I-35 corridor locations. However, this could change if the pseudo-convective boundary is able to slide farther south. For mid- to late-week, at least scattered showers are expected during the afternoon hours as instability occurs in the high PWAT air. Both ECMWF and GFS models indicate tropical activity could be possible across portions of the far southern Gulf of Mexico or the Bay of Campeche in the Wednesday/Thursday time-frame. All guidance at this time suggests this potential system to remain well south of the region. However, if anything changes, we'll keep you apprised. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 76 98 77 99 78 / 20 20 10 20 30 Austin Bergstrom Intl Airport 75 97 77 97 77 / 20 20 10 20 30 New Braunfels Muni Airport 74 97 76 96 76 / 20 20 20 20 30 Burnet Muni Airport 72 94 74 95 74 / 20 20 10 20 20 Del Rio Intl Airport 77 97 76 99 78 / 20 30 20 20 20 Georgetown Muni Airport 75 96 75 97 75 / 20 20 10 20 30 Hondo Muni Airport 74 99 75 98 75 / 20 20 20 20 20 San Marcos Muni Airport 75 96 76 96 76 / 20 20 20 20 30 La Grange - Fayette Regional 75 96 77 96 77 / 20 40 20 40 30 San Antonio Intl Airport 77 96 77 95 78 / 20 20 20 20 20 Stinson Muni Airport 76 96 77 94 78 / 20 20 20 20 20 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && Mesoscale/Aviation...TB3 Synoptic/Grids...09 Public Service/Data Collection...YB
Hazardous weather outlook, Aug 4, 4:37 AM CDT, 14 hours 21 minutes before
Hazardous Weather Outlook National Weather Service Austin/San Antonio TX 437 AM CDT Fri Aug 4 2017 TXZ171>173-183>194-202>209-217>225-228-051100- Llano-Burnet-Williamson-Val Verde-Edwards-Real-Kerr-Bandera- Gillespie-Kendall-Blanco-Hays-Travis-Bastrop-Lee-Kinney-Uvalde- Medina-Bexar-Comal-Guadalupe-Caldwell-Fayette-Maverick-Zavala- Frio-Atascosa-Wilson-Karnes-Gonzales-De Witt-Lavaca-Dimmit- 437 AM CDT Fri Aug 4 2017 This Hazardous Weather Outlook is for South-Central Texas.. .DAY ONE...Today And Tonight. Isolated pockets of heavy rainfall are possible this afternoon along and east of I-35. Given the dry antecedent conditions flooding impacts, if any at all, would be very minor. .DAYS TWO THROUGH SEVEN...Saturday through Thursday. Afternoon heat index values of 104 to 108 degrees will be possible Sunday through Tuesday across portions of South Central Texas, outside of the Hill Country. .SPOTTER INFORMATION STATEMENT... Spotter activation is not anticipated.
In the hours before
Special weather statement, Aug 4, 6:58 PM CDT, 0 minutes before
Special Weather Statement
National Weather Service Austin/San Antonio TX
658 PM CDT FRI AUG 4 2017
TXZ224-225-050030-
Lavaca TX-De Witt TX-
658 PM CDT FRI AUG 4 2017
...SIGNIFICANT WEATHER ADVISORY FOR EAST CENTRAL DEWITT AND SOUTH
CENTRAL LAVACA COUNTIES UNTIL 730 PM CDT...
At 657 PM CDT, Doppler radar was tracking a strong thunderstorm near
Fordtran, or 16 miles southeast of Yoakum. This storm was slowly
moving west at 5 mph.
Nickel size hail and wind gusts up to 50 mph will be possible with
this storm. Some weak rotation was also noted on radar.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.
To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Austin San Antonio.
&&
LAT...LON 2914 9683 2906 9694 2910 9698 2903 9708
2902 9711 2922 9704 2924 9682 2915 9681
TIME...MOT...LOC 2357Z 003DEG 1KT 2913 9695
TB3Nearby
Special Weather Statements in Texas, 2017Every special weather statement in 2017
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.