The Mojave Desert Severe Weather Event of July 10, 2008

 

Overview

 

Monsoonal moisture moving northwestward into the Mojave Desert helped set the stage for a severe weather event during the afternoon and evening hours of July 10, 2008. During this time, the National Weather Service Office in Las Vegas issued a total of 9 Severe Thunderstorm Warnings and 3 Flash Flood Warnings. In addition, the Storm Prediction Center in Norman, OK issued a Severe Thunderstorm Watch for San Bernardino, Mohave and Clark Counties.

 

A surge of deeper moisture worked northwestward beginning on the night of July 9th and through the day on July 10th and was evidenced in the VAD wind profile from the Yuma Doppler Radar which showed southerly flow in the low levels. A very sharp dewpoint gradient was noted with this northwestward advance of moisture and this boundary seemed to mark the western and northern limit of convective development during the afternoon and evening hours of the 10th. This dewpoint gradient was oriented roughly from Northern Clark County through extreme southern Nye County and then southwestward across the western fringes of San Bernardino County. The GFS model at 00Z on July 11th initialized precipitable water values as high as 0.75 inches near Las Vegas (See Image 1).

 

 

Image 1 – Precipitable Water Values at 00Z 7-11-2008 across the area (initialized by the GFS).

In addition to having a sufficient surge of moisture into the area, instability parameters and shear were also supportive of severe thunderstorm development across much of the Mojave Desert. The 12Z July 10th Flagstaff sounding showed a most unstable CAPE of 2448 J/Kg, a surface CAPE of 2169 J/Kg (substantial CAPE in the hail growth zone was also evident) and a forecast surface Lifted Index of -8 along with vertical wind shear of 30-35 knots. By contrast, the 12Z July 10th sounding from Desert Rock showed very minimal CAPE in the hail growth zone and had most unstable CAPE of 16 J/Kg, a surface CAPE of 56 J/Kg and a forecasted surface Lifted Index of -1. The height of the -20C level (a critical level looked at for hail) during the afternoon hours of the 10th looks to have been between 24,500 and 27,500 feet based on the 00Z July 11th soundings from Flagstaff and Desert Rock.

 

 

Image 2- Visible satellite image with observed lightning (in lime green) at 00z 7-11-2008. Note the large area of thunderstorms over Mohave County and a smaller area in eastern San Bernardino County.

 

Thunderstorms initially developed across Mohave County during the mid-afternoon hours. These storms produced several reports of wind damage and flash flooding in the Kingman area as well as penny-sized hail on the Hualapai Reservation. Storms then developed across eastern San Bernardino County and also in central and southern Clark County and extreme southern Nye County near Pahrump. Thunderstorms did not develop in the Las Vegas Valley but several weak outflow boundaries did migrate into the area, affecting wind and temperature.

 

Although some of the storms that did develop remained over rural areas, the Colorado River Valley communities from Laughlin southward were affected as the evening progressed and outflow boundaries from storms that developed across Mohave County moved westward. The outflow boundaries from the Mohave County storms eventually collided with outflow boundaries from storms that developed in eastern San Bernardino County creating a convergence zone in the vicinity of the Colorado River. Several reports of wind damage were received from communities along the Colorado River in Mohave County. Low visibility from blowing dust, with reports as low as 100 feet in Laughlin, developed in association with thunderstorm outflow winds.

 

Another likely severe storm developed north of Barstow in the evening. The most intense portion of the storm was over the open desert but on the periphery a 54 mph wind gust was recorded. Radar imagery also showed a three body scatter spike with this storm, indicative large hail production. This storm also unleashed heavy rains that caused flash flooding at the Calico Ghost Town Campground.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Radar Imagery

 

Below are some radar images of storms from this event.

 

 

Image 3 – KESX 0.5 degree Reflectivity showing Severe Thunderstorm over Mohave County just east of Hualapai Peak that produced penny size hail on eastern side of the Hualapai Reservation. Also, note the outflow boundary pushing east from this storm towards Kingman. A second outflow boundary is clearly evident moving eastward from the thunderstorms south of Mountain Pass, California.

 

 

 

 

 

Image 4 – KESX 0.5 degree Velocity showing a small area of rotation north of Mountain Pass, CA that prompted a severe thunderstorm warning for that cell. This storm remained over a rural area.

 

 

 

Image 5 - Radar image of storm that prompted several warnings near Dolan Springs, but remained over a rural mountain area. Note the base reflectivity was around 70 dBZ with this storm.

 

 

Image 6 – KSEX 0.5 degree reflectivity showing storms moving through the Kingman area. Note the outflow boundaries moving towards the Colorado River from the west and east.

 

 

Image 7 – KESX 0.5 degree Reflectivity showing storms moving through Laughlin and heading towards the Colorado River. Note the colliding outflow boundaries further north along the river.

 

 

 

Image 8 – KEYX WSR88-D Radar reflectivity images for a thunderstorm northeast of Barstow over a rural area. A TBSS was observed at several elevation slices. This is a cross section using FSI at the lowest slice 2.4 deg. The CAPPI was set near 27 kft, 70 dBZ above the -20 deg C. level.  (Special thanks to Barry Pierce for this image).

 

 

 

 

 

 

 

 

 

 

 

 

 

Storm Reports

 

This is a preliminary list of storm reports from this event. A special thanks to our spotters and HAM Radio members for many of these reports!

 

000
NWUS55 KVEF 121630
LSRVEF
 
PRELIMINARY LOCAL STORM REPORT...SUMMARY
NATIONAL WEATHER SERVICE LAS VEGAS NV
930 AM PDT SAT JUL 12 2008
 
..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..
 
0245 PM     HAIL             15 SSE PEACH SPRINGS    35.33N 113.33W
07/10/2008  E0.25 INCH       MOHAVE             AZ   TRAINED SPOTTER
 
            PEA SIZE HAIL WAS REPORTED BY A SPOTTER AT THE DIAMOND M.
            RANCH.
 
0355 PM     HAIL             2 NE PEACH SPRINGS      35.55N 113.40W
07/10/2008  E0.25 INCH       MOHAVE             AZ   TRAINED SPOTTER
 
            PEA SIZE HAIL AND HEAVY RAIN ACCOMPANIED BY BLOWING DUST
            WAS REPORTED BY A SPOTTER.
 
0358 PM     HAIL             8 E HUALAPAI PEAK       35.07N 113.76W
07/10/2008  E0.75 INCH       MOHAVE             AZ   PUBLIC
 
            PENNY SIZE HAIL FELL ON THE EASTERN SIDE OF THE HUALAPAI
            TRIBE RESERVATION. THE TIME WAS ESTIMATED BASED ON RADAR.
 
 
0416 PM     TSTM WND GST     KINGMAN                 35.21N 114.03W
07/10/2008  M46.00 MPH       MOHAVE             AZ   ASOS
 
            A 46 MPH WIND GUST WAS REPORTED AT THE KINGMAN AIRPORT
            FROM A THUNDERSTORM OUTFLOW BOUNDARY.
 
0419 PM     LIGHTNING        HUALAPAI PEAK           35.07N 113.90W
07/10/2008                   MOHAVE             AZ   TRAINED SPOTTER
 
            A SPOTTER REPORTED THAT LIGHTNING HAD STARTED 2 FIRES IN
            THE HUALAPAI MOUNTAIN RANGE.
 
0455 PM     HAIL             PAHRUMP                 36.21N 115.99W
07/10/2008  E0.25 INCH       NYE                NV   TRAINED SPOTTER
 
0505 PM     LIGHTNING        PAHRUMP                 36.21N 115.99W
07/10/2008                   NYE                NV   TRAINED SPOTTER
 
            A SPOTTER REPORTED REPORTED POWER LINES WERE STRUCK AND
            KNOCKED DOWN BY LIGHTNING IN PAHRUMP.
 
0520 PM     HAIL             KINGMAN                 35.21N 114.03W
07/10/2008  E0.50 INCH       MOHAVE             AZ   AMATEUR RADIO
 
            DIME SIZE HAIL WAS REPORTED AT THE KINGMAN AIRPORT.
 
0530 PM     TSTM WND GST     KINGMAN                 35.21N 114.03W
07/10/2008  E60.00 MPH       MOHAVE             AZ   AMATEUR RADIO
 
            AN ESTIMATED 60 MPH WIND GUST WAS REPORTED IN KINGMAN.
 
0530 PM     TSTM WND DMG     KINGMAN                 35.21N 114.03W
07/10/2008                   MOHAVE             AZ   TRAINED SPOTTER
 
            THUNDERSTORM WINDS BLEW DOWN WOODEN FENCES IN KINGMAN
            ALONG WALNUT CREEK ROAD AND ALSO BLEW DOWN A 200 POUND
            SATELLITE DISH. IN ADDITION, THUNDERSTORM WINDS RIPPED
            THE ROOF OF A MOBILE HOME GARAGE. A 54MPH WIND GUST WAS
            MEASURED IN DOWNTOWN KINGMAN. THE TIME OF THESE EVENTS
            WERE ESTIMATED.
 
0545 PM     TSTM WND GST     GOLDEN VALLEY           35.22N 114.22W
07/10/2008  M54.00 MPH       MOHAVE             AZ   TRAINED SPOTTER
 
            A SPOTTER MEASURED A 54 MPH WIND GUST IN GOLDEN VALLEY.
 
0545 PM     FLASH FLOOD      KINGMAN                 35.21N 114.03W
07/10/2008                   MOHAVE             AZ   AMATEUR RADIO
 
            ROADS WERE REPORTED FLOODED IN THE KINGMAN AREA.
 
0600 PM     TSTM WND DMG     LAKE HAVASU CITY        34.45N 114.33W
07/10/2008                   SAN BERNARDINO     AZ   NEWSPAPER
 
            THUNDERSTORM WINDS KNOCKED DOWN A LARGE TREE IN LAKE
            HAVASU CITY. THE TIME OF THIS EVENT WAS ESTIMATED.
 
0605 PM     TSTM WND DMG     BULLHEAD CITY           35.15N 114.56W
07/10/2008                   MOHAVE             AZ   TRAINED SPOTTER
 
            SIGNS WERE BLOWN DOWN OFF OF SEVERAL BUSINESSES IN
            BULLHEAD CITY.
 
0615 PM     TSTM WND GST     BULLHEAD CITY           35.15N 114.56W
07/10/2008  M64.00 MPH       MOHAVE             AZ   TRAINED SPOTTER
 
            A SPOTTER MEASURED SUSTAINED WINDS OF 50 MPH WITH A GUST
            OF 64 MPH IN BULLHEAD CITY.
 
0620 PM     TSTM WND GST     BULLHEAD CITY           35.15N 114.56W
07/10/2008  E60.00 MPH       MOHAVE             AZ   TRAINED SPOTTER
 
            A SPOTTER ESTIMATED A 60 MPH WIND GUST IN BULLHEAD CITY
            IN ASSOCIATION WITH A THUNDERSTORM OUTFLOW BOUNDARY. THE
            WIND WAS STRONG ENOUGH TO KNOCK DOWN HIS NEIGHBOR WHO WAS
            OUTSIDE TRYING TO COLLECT HIS TRASH CANS.
 
0628 PM     FLASH FLOOD      KINGMAN                 35.21N 114.03W
07/10/2008                   MOHAVE             AZ   AMATEUR RADIO
 
            BANK STREET WAS REPORTED FLOODED IN THE BUTLER AREA OF
            KINGMAN. THE MOUNT BULL ALERT GAGE RECORDED 1.16 INCHES
            OF RAIN IN THE PAST 2 HOURS.
 
0635 PM     TSTM WND DMG     8 S BULLHEAD CITY       35.03N 114.56W
07/10/2008                   MOHAVE             AZ   TRAINED SPOTTER
 
            THUNDERSTORM WINDS BLEW AN AWNING AS WELL AS SOME
            SHINGLES OFF A HOUSE.
 
0637 PM     TSTM WND GST     LAUGHLIN                35.16N 114.58W
07/10/2008  E50.00 MPH       CLARK              NV   TRAINED SPOTTER
 
0703 PM     TSTM WND GST     NEEDLES                 34.81N 114.61W
07/10/2008  M51.00 MPH       SAN BERNARDINO     CA   ASOS
 
            A 51 MPH WIND GUST WAS MEASURED AT THE NEEDLES AIRPORT.
 
0800 PM     TSTM WND GST     18 SSE TRONA            35.51N 117.27W
07/10/2008  M54.00 MPH       SAN BERNARDINO     CA   MESONET
 
            A 54 MPH WIND GUST WAS MEASURED AT THE CLR05 MESONET
            SITE.
 
0915 PM     LIGHTNING        9 ENE BARSTOW           34.93N 116.92W
07/10/2008                   SAN BERNARDINO     CA   NEWSPAPER
 
            THE SAN BERNARDINO COUNTY DEPARTMENT OF PUBLIC WORKS
            REPORTED LIGHTNING DOWNED A NUMBER OF POWER LINES IN THE
            YERMO AREA CAUSING SOME ROAD CLOSURES. THE TIME OF THIS
            EVENT WAS ESTIMATED.
 
0915 PM     FLASH FLOOD      10 ENE BARSTOW          34.93N 116.90W
07/10/2008                   SAN BERNARDINO     CA   NEWSPAPER
 
            HEAVY RAINS CAUSED FLASH FLOODING AT THE CALICO GHOST
            TOWN AND WASHED OUT MOST OF THE CAMPGROUND. ROADS AT THE
            CAMGROUND WERE COVERED IN MUD AND DEBRIS. THE CALICO
            GHOST TOWN PARK LOST POWER DUE TO THE STORM. THE TIME OF
            THIS EVENT WAS ESTIMATED.
 
 
&&
THIS IS AN UPDATED SUMMARY OF REPORTS FROM THE THUNDERSTORMS THAT
OCCURRED IN PARTS OF THE MOJAVE DESERT THURSDAY AFTERNOON AND
EVENING.

 

A final thanks is extended to the staff at the National Weather Service who worked up to and during this event for information used in this report and to staff members who reviewed it.