Alert archive / Texas / Severe Thunderstorm Warnings in 2001

Severe Thunderstorm Warning 15, NWS Brownsville, TX

May 20, 2001Zapata County, Texas

NWS Brownsville, TX issued this severe thunderstorm warning at May 20, 2001, 7:12 PM CDT for Zapata County, Texas. It was in force for 63 min. 2 reports came from inside the area while it was in force.

The area

The outline the Iowa Environmental Mesonet reconstructed for it; the warning itself named whole counties, with what was reported inside it.

The facts

Issued: May 20, 2001, 7:12 PM CDT (00:12 UTC)
Expired: May 20, 2001, 8:15 PM CDT
In force: 63 min
Issued by: NWS Brownsville, TX
Area: Whole counties; the outline is the Mesonet’s reconstruction

County Zapata County, TX

The radar

The Corpus Christi radar (KCRP), 199 km from the middle of the area, began a volume at 00:12 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.

What was reported inside it

Time	Report	Where	Remark
May 20, 7:20 PM CDT	Hail 0.75	San Ygnacio, TX
May 20, 7:30 PM CDT	Hail 1	San Ygnacio, TX	Quarter size hail reported by public along Highway 3169.

NCEI Storm Data entries that began inside the alert's area while it was in force. Before 2003 the local storm report archive is thin, so this is the record of what happened rather than what was phoned in.

The nearest sounding before it

Corpus Christi, TX (KCRP), launched 00:00Z, 0.2 hours before the alert went out and 212 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: 1709 J/kg
Mixed-layer CIN: -209 J/kg
Mixed-layer LCL: 1168 m above ground
0-6 km bulk shear: 50 kt
0-1 km storm-relative helicity: 60 m²/s²
0-3 km storm-relative helicity: 65 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.9

Open this sounding in Storm Lab

The text

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

000 
WUUS54 KBRO 210012
SVRBRO
TXC505-210115-

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE BROWNSVILLE TX
712 PM CDT SUN MAY 20 2001

THE NATIONAL WEATHER SERVICE HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  ZAPATA COUNTY IN DEEP SOUTH TEXAS

* UNTIL 815 PM CDT

* AT 708 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM 13 MILES NORTHWEST OF ZAPATA...MOVING NORTHEAST
  AT 30 MPH. THIS SEVERE THUNDERSTORM WILL LIKELY PRODUCE HAIL TO THE
  SIZE OF NICKELS TO QUARTERS...AND WINDS IN EXCESS OF 60 MPH.

* THE SEVERE THUNDERSTORM WILL BE NEAR...
   ZAPATA BY 720 PM CDT.

REPORT SEVERE WEATHER TO THE NEAREST LAW ENFORCEMENT AGENCY. THEY
WILL RELAY YOUR REPORT TO THE NATIONAL WEATHER SERVICE OFFICE.

LAT...LON 2704 9957 2665 9937 2713 9898 2726 9917

CASTILLO

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Brownsville, TX wrote its last area forecast discussion before this severe thunderstorm warning went out at May 20, 4:02 PM CDT, 3 hours 10 minutes earlier.

Area forecast discussion, May 20, 4:02 PM CDT, 3 hours 10 minutes before

DEEP SOUTH TEXAS FORECAST DISCUSSION...CORRECTION FOR SCA WORDING
NATIONAL WEATHER SERVICE BROWNSVILLE TX
230 PM CDT SUN MAY 20 2001

WATER VAPOR IMAGERY CLEARLY SHOWS A LARGE UPPER-LOW OVER SOUTHERN
SASKATCHEWAN...NOW MOVING SOUTH INTO THE NORTHERN PLAINS.  AS THIS
NORTHERN STREAM WAVE PHASES WITH A SOUTHERN STREAM WAVE MOVING
ACROSS OKLAHOMA AT THIS TIME...A LARGE LONGWAVE TROUGH WILL DEVELOP
OVER THE CENTRAL PLAINS...AND ALLOW AN UNSEASONABLY COLD CANADIAN
AIRMASS TO MOVE SOUTH AND EAST.  A COLD FRONT WILL MOVE RAPIDLY
THROUGH THE LOWER VALLEY ON MONDAY EVENING...CLEARING THE RIO GRANDE
RIVER SHORTLY AFTER MIDNIGHT.

SHOWERS AND THUNDERSTORMS ARE A GOOD POSSIBILITY AREA-WIDE BEGINNING
MONDAY EVENING.  STRENGTH OF LOW-LEVEL CONVERGENCE ALONG THE COLD
FRONT...AND SOMEWHAT FAVORABLE TIMING OF FRONTAL PASSAGE IN THE
EARLY EVENING ACROSS THE NORTH WILL ENHANCE THE CHANCES FOR
CONVECTION THERE.  HOWEVER...WEAK FORECASTED WIND
PROFILES...SLIGHTLY CONFLUENT UPPER-FLOW...AND LACK OF UPPER SUPPORT
IN THE FORM OF CYCLONIC VORTICITY ADVECTION WILL LIKELY INHIBIT
SEVERE THREAT.  FOR NOW...WILL INCREASE POPS TO 20 PERCENT ON
MONDAY...AND MAINTAIN 40 PERCENT POPS FOR MONDAY NIGHT AND TUESDAY.
SEVERE THREAT WILL BE HIGHEST IN NORTHERN COUNTIES OF THE CWA...AND
WILL LIKELY COME IN THE FORM OF LARGE HAIL.  CURRENT FORECAST
NUMBERS FOR TEMPS LOOK GOOD...AND WILL STICK WITH THEM.  COLDEST
TEMPERATURES ON TUESDAY WILL BE CLOSER TO SURFACE RIDGE AXIS IN THE
WEST.

UPPER NORTHWEST FLOW WILL PERSIST THROUGH NEXT WEEKEND...AS AN
UNSEASONABLY COLD UPPER CYCLONE REMAINS OVER THE EASTERN U.S.  A FEW
WEAK SHORTWAVE TROUGHS EMBEDDED IN THE UPPER NORTHWEST FLOW WILL
BRING CHANCES OF RAIN TO THE AREA FOR FRIDAY AND SATURDAY.  SKIES
SHOULD BEGIN TO CLEAR ON SUNDAY...AS UPPER RIDGE DEVELOPS OVER THE
SOUTHERN PLAINS.

MARINE...SOUTHEAST WINDS AT 16 KNOTS AND 4 FOOT SEAS CURRENTLY
REPORTED OFFSHORE.  SCA MAY BE NEEDED FOR THE BAY AGAIN TOMORROW...
AND WILL LIKELY BE NEEDED ACROSS ALL COASTAL WATERS AFTER PASSAGE OF
A STRONG COLD FRONT ON MONDAY EVENING.  SCATTERED SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE ON MONDAY EVENING AND TUESDAY.

PRELIMINARY NUMBERS:
BRO BB 077/093 070/078 065  00/20/40/40/00
HRL BB 076/095 069/078 064  00/20/40/40/00
MFE BB 076/097 070/076 063  00/20/40/40/00
RGC BB 075/101 068/074 060  00/20/40/40/00
SPI BB 077/085 073/079 067  00/20/40/40/00

SYNOPTIC...DD (65) / AVIATION-MARINE...60 / MESO...SM

INTERNET ADDRESS...WWW.SRH.NOAA.GOV/BRO

.BRO...SCA TONIGHT FOR GMZ130.

The office that day

Everything else NWS Brownsville, TX issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 21, 4:56 PM CDT	Severe Thunderstorm Warning	BRO	Jim Hogg, Zapata	49 min
May 21, 5:35 PM CDT	Severe Thunderstorm Warning	BRO	Jim Hogg	55 min
May 21, 5:40 PM CDT	Flash Flood Warning	BRO	Jim Hogg	3 hr
May 21, 6:00 PM CDT	Severe Thunderstorm Warning	BRO	Brooks	60 min
May 21, 6:19 PM CDT	Tornado Warning	BRO	Brooks, Jim Hogg, Starr	56 min
May 21, 6:19 PM CDT	Tornado Warning	BRO	Hidalgo	56 min
May 21, 6:55 PM CDT	Severe Thunderstorm Warning	BRO	Hidalgo, Starr	65 min

Nearby

Severe Thunderstorm Warnings in Texas, 2001 Every severe thunderstorm warning in 2001

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; verification from NCEI's Storm Data; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.