Alert archive / Arizona / Severe Thunderstorm Warnings in 1999
Severe Thunderstorm Warning 8, NWS Las Vegas, NV
NWS Las Vegas, NV issued this severe thunderstorm warning at Aug 29, 1999, 5:33 PM MST for Mohave County, Arizona. It was in force for 42 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
- Aug 29, 1999, 5:33 PM MST (00:33 UTC)
- Expired
- Aug 29, 1999, 6:15 PM MST
- In force
- 42 min
- Issued by
- NWS Las Vegas, NV
- Area
- Whole counties; the outline is the Mesonet’s reconstruction
County Mohave County, AZ
The nearest sounding before it
Flgstf/Belemont, AZ (KFGZ), launched 00:00Z, 0.6 hours before the alert went out and 185 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
- 201 J/kg
- Mixed-layer CIN
- -14 J/kg
- Mixed-layer LCL
- 1506 m above ground
- 0-6 km bulk shear
- 10 kt
- 0-1 km storm-relative helicity
- -1 m²/s²
- 0-3 km storm-relative helicity
- 14 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
The text of this product is not in the archive. The NWS text archive before 2002 is incomplete.
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 Aug 29, 2:40 PM MST, 2 hours 53 minutes earlier.
Area forecast discussion, Aug 29, 2:40 PM MST, 2 hours 53 minutes before
MOJAVE DESERT/SOUTHERN GREAT BASIN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAS VEGAS NV 240 PM PDT SUN AUG 29 1999 SYNOPSIS...STRONG SOUTHERLY FLOW ALOFT AHEAD OF A LOW PRESSURE SYSTEM MOVING TOWARD NORTHERN CALIFORNIA WILL CONTINUE TO DRAW UP ABUNDANT MONSOONAL MOISTURE INTO THE SOUTHERN HALF OF THE REGION INTO MONDAY. THE AIRMASS WILL BECOMING INCREASINGLY UNSTABLE THIS EVENING AND OVERNIGHT LEADING TO NUMEROUS THUNDERSTORMS AND LOCALLY HEAVY RAIN. THE LOW PRESSURE SYSTEM WILL MOVE OVER THE WEST COAST ON MONDAY...RESULTING IN WINDY CONDITIONS AND LOWER TEMPERATURES. INCREASED SOUTHWEST FLOW ALOFT ON MONDAY WILL SPREAD DRIER AIR ACROSS THE REGION DURING THE DAY. THE EXCEPTION WILL BE NORTHWEST ARIZONA WHERE THE THREAT OF THUNDERSTORMS WILL REMAIN HIGH. ON TUESDAY...ALL AREAS WILL BE DRY WITH WINDY CONDITIONS IN THE FAR SOUTH. DISCUSSION...EVERYTHING GOING ABOUT AS EXPECTED WITH RAPID INCREASE IN LOW LEVEL MOISTURE ACROSS THE SOUTH THROUGH THE DAY. PW SOUNDER SHOWING 2 INCH PLUME UP TO LAKE HAVASU AS OF COUPLE HOURS AGO WITH 1.5 LINE UP TO SRN CLARK AND MOST OF MOHAVE. THIS MUCH HIGHER THAN MODELS SHOWED BUT NOT UNEXPECTED. LAS VEGAS 88D VAD WIND PROFILE SHOWING LIGHT SE FLOW UP TO AROUND 500MB WITH EVEN WATER VAPOR SHOT SHOWING FLOW REVERSAL AND DEVELOPING SE FLOW. IN ADDITION...THE REMNANTS OF THE INVERTED TROUGH IS STILL MOVING NW IN THIS FLOW AND IS CURRENTLY MOVING INTO MOHAVE COUNTY AND IS FORECAST TO MOVE TOWARD CLARK COUNTY AFT 06Z. WILL ISSUE FLASH FLOOD WATCH FOR ALL OF NW ARIZONA...CLARK COUNTY IN SRN NV AND EXTREME ERN SAN BERNARDINO COUNTY IN CA. MODELS NOT SHOWING STRONG DYNAMICS BUT WHAT DOES DEVELOP WILL ACT ON VERY MOIST AIRMASS. LAPS ANALYSIS SHOWING CAPES IN EXCESS OF 2500 J/KG OVER SERN SAN BERNARDINO AND EXTREME SWRN MOHAVE COUNTY WITH LIS OF -4. STRONG CELLS ALREADY ERUPTING IN AND NEAR THIS AREA AND WILL LIKELY SPREAD AND DEVELOP NORTH THROUGH THE EVENING AND CONTINUE OVERNIGHT. THUNDERSTORMS WILL BEGIN TO BE PUSHED OUT TOMORROW IN SRN NV AS SW FLOW KICKS IN BUT NW AZ WILL LIKELY CONTINUE ALL DAY WITH POTENTIAL FOR SEVERE WEATHER. OTHERWISE...WINDS WILL BE ON THE INCREASE IN THE SHORT TERM WITH COOLING TEMPERATURES. WINDY WORDING ALREADY MENTIONED FOR TOMORROW AND WILL BE ADDED TO FAR S ON TUESDAY. EXTENDED LOOKS BUT UK IS MORE AGGRESSIVE WITH WRN ENERGY IN PERSISTENT PACNW TROUGH AND MAY CREATE A CHANCE OF SHOWER FOR NWRN ZONES BY DAY 5 ALONG WITH MORE WIND. WILL JUST KEEP A DRY EXTENDED FOR NOW WITH TEMPERATURES A LITTLE BELOW SEASONAL NORMS. SKRBAC LAS...A FLASH FLOOD WATCH IS IN EFFECT FOR PART OF THE AREA TONIGHT. CHECK THE LATEST FLASH FLOOD STATEMENT FOR DETAILS...
The office that day
Everything else NWS Las Vegas, NV issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 29, 6:06 PM MST | Severe Thunderstorm Warning | VEF | Clark | 54 min |
| Aug 30, 8:20 AM MST | Flash Flood Warning | VEF | Clark | 3 hr |
Nearby
Severe Thunderstorm Warnings in Arizona, 1999Every severe thunderstorm warning in 1999
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.