Alert archive / Nevada / Severe Thunderstorm Warnings in 1998
Severe Thunderstorm Warning 8, NWS Las Vegas, NV
NWS Las Vegas, NV issued this severe thunderstorm warning at Jul 21, 1998, 4:14 PM PDT for Clark County, Nevada. It was in force for 61 min. No storm report in the archive falls inside the area while it was in force.
The area
The counties it named.
The facts
- Issued
- Jul 21, 1998, 4:14 PM PDT (23:14 UTC)
- Expired
- Jul 21, 1998, 5:15 PM PDT
- In force
- 61 min
- Issued by
- NWS Las Vegas, NV
- Area
- Whole counties
County Clark County, NV
The nearest sounding before it
Mercury/Desert R, NV (KDRA), launched 12:00Z, 11.2 hours before the alert went out and 99 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
- 122 J/kg
- Mixed-layer CIN
- -198 J/kg
- Mixed-layer LCL
- 2317 m above ground
- 0-6 km bulk shear
- 16 kt
- 0-1 km storm-relative helicity
- -20 m²/s²
- 0-3 km storm-relative helicity
- -5 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
961 WUUS1 KLAS 212315 RRA SVRLAS NVC003-220015- BULLETIN - IMMEDIATE BROADCAST REQUESTED SEVERE THUNDERSTORM WARNING NATIONAL WEATHER SERVICE LAS VEGAS NV 414 PM PDT TUE JUL 21 1998 * SEVERE THUNDERSTORM WARNING FOR CENTRAL CLARK COUNTY IN SOUTHERN NEVADA * UNTIL 515 PM PDT * SOME LOCATIONS AFFECTED NORTH LAS VEGAS AT 405 PDT RADAR INDICATED A SEVERE THUNDERSTORM NEAR THE U.S. 95 AND RANCHO INTERCHANGE. MOVEMENT WAS TO THE EAST OR SOUTHEAST AT 15 MPH. DAMAGING WINDS IN EXCESS OF 58 MPH AND HAIL GREATER THAN THREE QUATER OF AN INCH IN DIAMETER ARE LIKELY WITH THIS STORM. IF YOU ARE OUTDOORS...MOVE TO A PLACE OF SHELTER IMMEDIATELY IF A STORM APPROACHES. MOTORISTS SHOULD REMAIN ALERT FOR REDUCED VISIBILITIES DURING DOWNPOURS OF RAIN. STREETS MAY FLOOD QUICKLY.
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 Las Vegas, NV wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 21, 3:10 PM PDT, 1 hour 4 minutes earlier.
Area forecast discussion, Jul 21, 3:10 PM PDT, 1 hour 4 minutes before
MOJAVE DESERT/SOUTHERN GREAT BASIN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAS VEGAS NV 310 PM PDT TUE JUL 21 1998 SYNOPSIS...AN UPPER LEVEL HIGH PRESSURE SYSTEM WILL REMAIN NEAR THE FOUR CORNERS AREA THROUGH MUCH OF THE WEEK. THIS WILL CONTINUE TO BRING A FLOW OF MONSOONAL MOISTURE INTO THE REGION...HELPING TO FUEL SCATTERED AFTERNOON AND EVENING THUNDERSTORMS. DISCUSSION...PLENTY OF MOISTURE TODAY WITH 850 DEW POINT AXIS FROM SRN AZ INTO SOUTH CENTRAL NV. SURFACE DEW POINTS BEGINNING TO MIX OUT SOMEWHAT WITH 60 TO 65 DEGREES F REMAINING ACROSS EXTREME SRN NV AND IN EXCESS OF 70 DEGREES STILL POOLED OVER THE SE CA DESERTS AND COLORADO RIVER AS FAR N AS BLH AND EED. THUNDERSTORMS HAVE INITIATED MAINLY OVER THE MOUNTAINS IN NV AND NW AZ AND HAVE NOT BEEN IN ANY HURRY TO MOVE OFF DUE TO WEAK MID AND UPPER LEVEL FLOW. HOWEVER...AS STORMS CONTINUE TO GROW...ANTICYCLONIC FLOW AROUND FOUR CORNERS HIGH WILL SLOWLY PUSH STORMS OFF MOUNTAINS AND INTO VALLEYS. OUTFLOW BOUNDARY INTERACTION WILL THEN CONTRIBUTE TO STORM FORMATION WITH THUNDERSTORMS CONTINUING INTO THE LATE EVENING. SYNOPTIC PATTERN CHANGES VERY LITTLE THROUGH THURSDAY WITH UPPER HIGH REMAINING NEAR FOUR CORNERS REGION PROVIDING S-SELY FLOW. LOW AND MID LEVEL MOISTURE/THETA-E AXIS REMAINS CLOSE TO A TPH TO YUM LINE. WITH WEAK FLOW OF PLENTY OF MOISTURE...MAIN THREAT WILL BE FLASH FLOODING WITH HIGHER POPS OF NGM MOS PREFERRED. VERY DIFFICULT TO FIND ANY SYNOPTIC SCALE TRIGGERING MECHANISMS BUT WILL CLOSELY WATCH MID/UPPER LEVEL DISTURBANCE NOW OFF BAJA COAST NEAR THE SPUR. NGM THE ONLY MODEL THAT SEEMS TO HAVE IDENTIFIED IT AND BRINGS IT N INTO SRN NV LATE WED NGT/THU. NOT READY TO BUY INTO THIS JUST YET BUT WOULD SEEM REASONABLE. OTHERWISE...MESOSCALE TRIGGERING MECHANISMS WILL DOMINATE WITH HEAVY RELIANCE ON SATELLITE TO HELP IDENTIFY AND TRACK THESE FEATURES. RIDGE REMAINS IN PLACE INTO THE EXTENDED AND SLOWLY WEAKENS. ANY DRYpING WILL ALSO BE SLOW SO CONTINUATION OF STANDARD MONSOON FORECAST THE BEST WAY TO GO. LAS 3343. NEMETH A FLASH FLOOD WATCH HAS BEEN ISSUED. PLEASE REFER TO THE LATEST FLASH FLOOD WATCH BULLETIN FOR DETAILS.
The office that day
Everything else NWS Las Vegas, NV issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 21, 3:12 PM PDT | Flash Flood Warning | VEF | Clark | 2 hr |
Nearby
Severe Thunderstorm Warnings in Nevada, 1998Every severe thunderstorm warning in 1998
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.