Severe Thunderstorm Warning 33, NWS Las Vegas, NV

000 
WWUS55 KVEF 072140
SVSVEF

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE LAS VEGAS NV
240 PM PDT THU AUG 7 2008

NVC003-072148-
/O.CAN.KVEF.SV.W.0033.000000T0000Z-080807T2200Z/
CLARK NV-
238 PM PDT THU AUG 7 2008

...THE SEVERE THUNDERSTORM WARNING FOR WEST CENTRAL CLARK COUNTY IS
CANCELLED...

THE THUNDERSTORM ALONG HIGHWAY 160 HAS WEAKENED AND IS NO LONGER 
SEVERE...THEREFORE THE SEVERE THUNDERSTORM WARNING HAS BEEN 
CANCELLED. WIND GUSTS TO 40 MPH...BLOWING DUST AND HEAVY RAIN ARE 
STILL POSSIBLE WITH THIS STORM. A FLASH FLOOD WARNING IS STILL IN 
EFFECT FOR PORTIONS OF WEST CENTRAL CLARK COUNTY...PARTICULARLY IN 
THE MOUNTAIN PASS SUMMIT AREA.


LAT...LON 3612 11535 3591 11530 3590 11556 3608 11557
TIME...MOT...LOC 2138Z 229DEG 7KT 3604 11540

$$

SC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
950 AM PDT THU AUG 7 2008

.SYNOPSIS...MOIST AND UNSTABLE AIR WILL REMAIN OVER SOUTHERN
NEVADA...NORTHWEST ARIZONA AND NEARBY SOUTHEAST CALIFORNIA TODAY
RESULTING IN ISOLATED TO SCATTERED THUNDERSTORMS. LOCALLY
HEAVY RAIN WILL BE POSSIBLE WITH SOME STORMS. A DRIER SOUTHWEST FLOW
IS FORECAST TO DEVELOP FOR THE WEEKEND AND EARLY NEXT WEEK WITH
THUNDERSTORMS CONFINED TO NORTHWEST ARIZONA. &&

.UPDATE...ROUGHLY THE EASTERN HALF OF THE FORECAST AREA PRETTY MOIST
AND FAIRLY UNSTABLE TODAY. CONVECTION WHICH DEVELOPED VERY EARLY
THIS MORNING IN FAR SOUTHEAST SAN BERNARDINO HAS BEEN MAINTAINING IF
NOT EXPANDING. UPDATED ZONES AND GRIDS EARLIER TO INCREASE POPS A
LITTLE. DO NOT ANTICIPATE ADDITIONAL UPDATES THIS MORNING.
&&

.PREVIOUS UPDATE...ELEVATED CONVECTION WAS DEVELOPING NEAR THE
SOUTHERN BORDER OF SAN BERNARDINO COUNTY AND MOHAVE COUNTY. THIS
DEVELOPMENT WAS ON THE NORTHERN PERIPHERY OF THE UPPER LEVEL
DISTURBANCE CENTERED AROUND YUMA. RECENT RADAR RETURNS SHOWED CELLS
WERE FAIRLY DISORGANIZED AND SHORT LIVED BUT OCCASIONAL LIGHTNING
STRIKES WERE DETECTED. THIS AREA OF UPPER LEVEL SUPPORT SHOULD
SLOWLY PUSH NORTH THOUGH 18Z. AN UPDATE WAS SENT TO INCLUDE ISOLATED
THUNDERSTORMS THIS MORNING ACROSS SOUTHERN SAN BERNARDINO AND MOHAVE
COUNTIES.

.PREV DISCUSSION.../415 AM PDT THU AUG 7 2008/...SHORT TERM...THE
DEEP MOISTURE BOUNDARY HAS CHANGED LITTLE FROM WEDNESDAY WITH THE
WESTERN EDGE EXTENDING FROM EASTERN SAN BERNARDINO COUNTY UP THROUGH
CENTRAL CLARK AND LINCOLN COUNTIES. A MORE SOUTHERLY MID LEVEL
STEERING FLOW IS FORECAST TODAY AND A WEAK DISTURBANCE EVIDENT
AROUND THE 400 MB LEVEL IS FORECAST BY THE 06Z NAM AND GFS TO MOVE
SLOWLY FROM NEAR YUMA UP THROUGH SOUTHEAST CALIFORNIA INTO SOUTHERN
NEVADA THE NEXT 12-18 HOURS. THE GFS APPEARS TO BE A LITTLE STRONGER
WITH THIS FEATURE. THIS MAY ENHANCE CONVECTION OVER EASTERN SAN
BERNARDINO AND CLARK COUNTIES AS LONG AS SURFACE HEATING IS
SUFFICIENT TO INITIATE...WHICH APPEARS TO BE THE CASE. THE GFS AND
ECMWF CONTINUE TO INDICATE SOUTHWEST FLOW GRADUALLY DRYING OUT THE
MID LEVELS FRIDAY AND SATURDAY...THOUGH THE ECMWF RESURGES LOW LEVEL
MOISTURE UP THE COLORADO RIVER VALLEY FRIDAY. DO NOT SEE A GOOD
REASON FOR THIS AND IT SEEMS OVERDONE. THE NAM SHOWS LESS SOUTHWEST
FLOW SATURDAY THAN THE GFS AND ECMWF. PREFER THE CONSISTENCY OF THE
GFS AND ECMWF AND WILL CONTINUE TO SHOW THE DIMINISHING THUNDERSTORM
COVERAGE FROM WEST TO EAST FRIDAY AND SATURDAY. THE MENTION OF
THUNDERSTORMS REMAINS CONFINED TO MOHAVE AND FAR EASTERN LINCOLN
COUNTIES SATURDAY.

.LONG TERM...AN UPPER LEVEL TROUGH AXIS LOOKS TO SWING THROUGH THE
THE NORTHERN HALF OF THE WESTERN CONUS ON SUNDAY IN ASSOCIATION WITH
A CLOSED UPPER LOW THAT HEADS ACROSS BRITISH COLUMBIA. THIS TROUGH
AXIS WILL HELP TO TURN THE FLOW ALOFT TO A WESTERLY DIRECTION WHICH
WILL SIGNIFICANTLY DRY OUT MUCH OF THE AREA. THE OPERATIONAL GFS
PLUNGES PWATS BELOW A HALF AN INCH AS FAR EAST AS A PIOCHE TO LAS
VEGAS TO AMBOY LINE AND THE ECMWF ALSO SHOWS SIGNIFICANT DRYING
TAKING PLACE AS WELL. AS A RESULT TWEAKED POPS DOWN EVEN FURTHER.

JUST HOW FAST MOISTURE WILL RETURN TO THE REGION WILL DEPEND UPON
HOW QUICK THE UPPER FLOW ACROSS THE WESTERN CONUS TRANSITIONS BACK
TO A RIDGE. MONDAY APPEARS TO BE A TRANSITION DAY...WITH GENERAL
MODEL CONSENSUS NOT SHOWING THE RIDGE BUILDING BACK IN UNTIL
TUESDAY. EVEN THEN WE WILL SEE A GRADUAL MOISTENING UP AND THIS
LOOKS TO BE CONFINED TO MAINLY MOHAVE COUNTY. AS WE APPROACH
WEDNESDAY THE WESTERN RIDGE LOOKS TO AMPLIFY GREATLY IN RESPONSE TO
DEEP TROUGHING IN THE EAST. THIS SHOULD HELP TO GRADUALLY TURN THE
UPPER FLOW ACROSS OUR AREA BACK TO MORE OF A SOUTH TO SOUTHEAST
DIRECTION ALLOWING MONSOONAL MOISTURE TO WORK BACK NORTHWARD ACROSS
THE REGION. HOWEVER...JUST HOW SOON THIS EXACTLY OCCURS AND FAR
NORTH IT WORKS IS A TOUGH CALL AT THIS POINT. UNTIL ENOUGH MOISTURE
RETURNS TEMPS WILL WARM UP AND HIGHS SHOULD REACH ABOUT 2 TO 4
DEGREES ABOVE NORMAL GIVEN THE PROGGED 500MB HEIGHTS ARE BETWEEN 588
AND 591 DM.
&&

.AVIATION...FOR MCCARRAN...THE POTENTIAL IMPACT FROM TSTMS ON THE
AIRPORT WILL AGAIN BE THE MAIN ISSUE TODAY. WHILE WINDS OVERALL
SHOULD BE SOUTHERLY...ANY OUTFLOW BOUNDARIES THAT DO DEVELOP WILL
CREATE THE POTENTIAL FOR ERRATIC SHIFTS IN WIND DIRECTION AND/OR
INCREASES IN SPEED. FOR NOW...PLAN TO LEAVE ANY TSTMS OUT OF THE TAF
AND JUST CARRY A CB IN WITH THE FORECASTED SKY COVER FOR THIS
AFTERNOON AND EVENING. THE APPROACH CORRIDORS WILL AGAIN SEE SHOWERS
AND TSTMS...MAINLY THIS AFTERNOON/EVENING...WITH THE MORMON MESA AND
PEACH SPRINGS CORRIDORS THE MOST LIKELY IMPACTED. FEW-SCT CLOUDS
AT/ABOVE 12K FEET TODAY INTO TONIGHT. TSTMS THAT DO DEVELOP SHOULD
WIND DOWN BETWEEN 3Z AND 6Z FRI...AND DRY CONDITIONS ARE EXPECTED
LATER TONIGHT WITH LIGHT DIURNAL WINDS.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...ANOTHER DAY WITH TSTMS BEING THE PRIMARY IMPACT ACROSS
THE AREA. SHOULD SEE THE BEST CHANCES FOR TSTMS AND BEST COVERAGE
ACROSS LINCOLN...CLARK...MOHAVE AND EASTERN SAN BERNARDINO COUNTIES.
THE MAIN ISSUES WITH STORMS WILL BE LOCALLY HEAVY DOWNPOURS DROPPING
VSBY TO MVFR LEVELS AND LOWERING CIGS TO AROUND 060K FEET AS WELL AS
ERRATIC WIND SHIFTS AND/OR INCREASES IN SPEEDS DUE TO TSTM OUTFLOW
BOUNDARIES. TYPICAL AFTERNOON/EVENING GUSTY SOUTHERLY WINDS AROUND
20 KTS EXPECTED AROUND KDRA AND IN THE OWENS VALLEY. OTHERWISE
GENERALLY FEW-SCT CLOUDS AOA 12K FEET TODAY INTO TONIGHT. TSTMS
SHOULD WIND DOWN BETWEEN 3Z AND 6Z FRI...AND GENERALLY DRY
CONDITIONS ARE EXPECTED TONIGHT WITH TYPICAL DIURNAL WINDS.
&&

.CLIMATE...LATE YESTERDAY EVENING AN OUTFLOW BOUNDARY MOVED
SOUTHWARD THROUGH THE LAS VEGAS VALLEY AND COOLER AIR BEHIND THIS
DROPPED THE TEMPERATURE AT MCCARRAN INTERNATIONAL AIRPORT TO 78
DEGREES. THIS ENDED THE RUN OF CONSECUTIVE DAYS WITH A MINIMUM
TEMPERATURE OF 80 DEGREES OR BETTER AT MCCARRAN AT 15 DAYS...MAKING
IT THE 4TH LONGEST SUCH STRETCH ON RECORD FOR LAS VEGAS SINCE 1937.
THE LAST TIME THE LOW TEMPERATURE AT MCCARRAN DROPPED BELOW 80
DEGREES WAS BACK ON JULY 21ST WHEN IT REACHED 78 DEGREES. IN
ADDITION...A SHOWER DROPPED 0.01 INCH AT MCCARRAN YESTERDAY
EVENING...GIVING THE AIRPORT MEASURABLE PRECIPITATION FOR THE FIRST
TIME SINCE JULY 26TH.
&&

.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
AZ...NONE.
CA...NONE.
&&

HARRISON/SALMEN/ADAIR/STACHELSKI

HTTP://WEATHER.GOV/LASVEGAS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LAS VEGAS NV
559 AM PDT THU AUG 7 2008

AZZ001>003-036-CAZ519>527-NVZ014>022-080700-
NORTHWEST PLATEAU-LOWER COLORADO RIVER VALLEY-NORTHWEST DESERTS-
LAKE MEAD NATIONAL RECREATION AREA-EASTERN SIERRA SLOPES-
OWENS VALLEY-WHITE MOUNTAINS OF INYO COUNTY-
DEATH VALLEY NATIONAL PARK-WESTERN MOJAVE DESERT-
EASTERN MOJAVE DESERT-MORONGO BASIN-CADIZ BASIN-
SAN BERNARDINO COUNTY-UPPER COLORADO RIVER VALLEY-
ESMERALDA AND CENTRAL NYE COUNTY-LINCOLN COUNTY-
NORTHEAST CLARK COUNTY-WESTERN CLARK AND SOUTHERN NYE COUNTY-
SHEEP RANGE-SPRING MOUNTAINS-LAS VEGAS VALLEY-
SOUTHERN CLARK COUNTY-
559 AM PDT THU AUG 7 2008 /559 AM MST THU AUG 7 2008/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF NORTHWEST
ARIZONA...SOUTHEAST CALIFORNIA AND SOUTHERN NEVADA.

.DAY ONE...TODAY AND TONIGHT

MOIST AND UNSTABLE AIR WILL LEAD TO ANOTHER ROUND OF ISOLATED TO
SCATTERED THUNDERSTORMS...MAINLY DURING THE AFTERNOON AND EVENING.
THUNDERSTORMS CAPABLE OF PRODUCING LOCALLY HEAVY RAIN CAN BE
EXPECTED OVER GENERALLY THE SAME AREA AS WEDNESDAY...MAINLY
SOUTHEAST NEVADA AND NORTHWEST ARIZONA. THE PRIMARY THREAT WILL BE
ISOLATED FLASH FLOODING. ISOLATED THUNDERSTORMS WITH LIGHT TO
MODERATE RAIN SHOWERS CAN BE EXPECTED OVER THE REST OF THE REGION.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

THUNDERSTORM COVERAGE DIMINISHES FROM WEST TO EAST FRIDAY THROUGH
THE WEEKEND AS DRIER SOUTHWEST FLOW DEVELOPS. ISOLATED
THUNDERSTORMS WILL BE CONFINED TO NORTHWEST ARIZONA SATURDAY
THROUGH WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.