Dust Storm and Lightning Strike in Arizona, September 10 to 12, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
318 PM PDT THU SEP 10 2015

.SYNOPSIS...MONSOON MOISTURE WILL KEEP THUNDERSTORMS IN THE FORECAST
ACROSS THE MOJAVE DESERT SOUTH OF LAS VEGAS INTO THIS EVENING.
MAINLY DRY AND HOT CONDITIONS ARE EXPECTED FRIDAY AS HIGH PRESSURE
STRENGTHENS OVERHEAD. CONFIDENCE CONTINUES TO INCREASE IN MOISTURE
ASSOCIATED WITH TROPICAL STORM LINDA TO PUSH NORTH ACROSS THE REGION
THIS WEEKEND INTO EARLY NEXT WEEK RESULTING IN COOLER TEMPERATURES
AND INCREASED CHANCES OF THUNDERSTORMS.
&&

.DISCUSSION...ISOLATED THUNDERSTORMS ACROSS SAN BERNARDINO AND
MOHAVE COUNTIES AND SOUTHERN CLARK COUNTY THIS AFTERNOON WILL
PROBABLY PERSIST INTO THE EVENING HOURS BUT WILL LOSE SUPPORT ONCE
THE SUN SETS. HIGH PRESSURE STRENGTHENING OVER NEVADA WILL SUPPRESS
CONVECTION FRIDAY AND DRIER AIR WILL PUSH SOUTH WITH CONVECTION
LIMITED TO MAINLY SOUTHWEST SAN BERNARDINO COUNTY. THE MOJAVE
PRESERVE AND HIGHER ELEVATIONS OF SOUTHERN MOHAVE COUNTY COULD
POSSIBLY SEE A STORM DEVELOP AS WELL. WITH THE STRONG HIGH PRESSURE
IN PLACE...MOST AREAS WILL SEE HIGH TEMPERATURES NEARLY 10 DEGREES
ABOVE NORMAL.

THE HIGH WILL WEAKEN SATURDAY WHILE WHAT IS LEFT OF FORMER HURRICANE
LINDA BEGINS TO APPROACH THE SOUTHERN CALIFORNIA COAST. AS A
RESULT...MOISTURE WILL BEGIN TO INCREASE AGAIN BY SATURDAY AFTERNOON
WITH THUNDERSTORM CHANCES ACROSS ALL OF SAN BERNARDINO COUNTY AND
SOUTHERN CLARK AND SOUTHERN MOHAVE COUNTIES.

SUNDAY HAS THE POTENTIAL TO BE AN ACTIVE DAY AREA WIDE AS THE
SHORTWAVE TROUGH ASSOCIATED WITH LINDA REMNANTS PUSHES NORTH INTO
NEVADA. PLENTY OF MOISTURE COMBINED WITH INSTABILITY AND THE
SHORTWAVE SHOULD LEAD TO AT LEAST SCATTERED SHOWERS AND
THUNDERSTORMS. THERE IS SOME CONCERN THAT EXTENSIVE CLOUD COVER IN
THE MORNING COULD LIMIT STORM DEVELOPMENT AND HEAVY RAIN POTENTIAL
SOMEWHAT BUT I AM NOT CONFIDENT THAT WILL BE THE CASE GIVEN THE
STRENGTH OF THE WAVE DEPICTED BY THE MODELS. A SIGNIFICANT DROP IN
TEMPERATURES IS EXPECTED FOR SUNDAY WITH HIGH TEMPERATURES BACK DOWN
TO NEAR NORMAL. SHOWERS AND THUNDERSTORMS WILL PERSIST INTO THE
EVENING BUT WE SHOULD SEE A DOWNWARD TREND FROM WEST TO EAST
OVERNIGHT AS THE SHORTWAVE EXITS.

MONDAY LOOKS TO BE ANOTHER INTERESTING DAY AS ANOTHER SHORTWAVE
BREAKING OFF OF A LONG WAVE PACIFIC TROUGH MOVES INTO CALIFORNIA.
THERE SHOULD STILL BE AMPLE MOISTURE IN PLACE TO INTERACT WITH THIS
SHORTWAVE TO PRODUCE AT LEAST SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS CENTRAL AND EASTERN PORTIONS OF THE FORECAST AREA. THE WEST
MAY ACTUALLY SEE ENOUGH DRY AIR MOVE IN TO SEVERELY LIMIT CHANCE OF
CONVECTION. TEMPERATURES ARE FORECAST TO DROP A LITTLE MORE MONDAY
COMPARED TO SUNDAY.

FOR TUESDAY THROUGH THURSDAY...NO CHANGES WERE MADE TO THE FORECAST.
THE LONG WAVE PACIFIC TROUGH WILL GRADUALLY TRAVERSE THE WESTERN
U.S. THROUGH THE PERIOD. WE COULD STILL SEE SOME SHOWERS AND
THUNDERSTORMS EAST TUESDAY BUT BY THURSDAY THE MOISTURE SHOULD BE
SCOURED OUT BY GENERALLY WESTERLY WINDS. TEMPERATURES LOOK TO BE A
LITTLE BELOW NORMAL THROUGH THE PERIOD.
&&

.AVIATION...FOR MCCARRAN...WINDS WILL FOLLOW TYPICAL DIURNAL TRENDS
THROUGH FRIDAY WITH EAST WINDS IN THE DAY AND SOUTH/SOUTHWEST WINDS
AT NIGHT. THUNDERSTORMS ARE EXPECTED TO REMAIN SOUTH OF THE AREA.
MOISTURE WILL INCREASE SUNDAY WITH ISOLATED TO SCATTERED
THUNDERSTORMS EXPECTED IN THE LAS VEGAS VALLEY WITH POTENTIAL FOR
GUSTY AND ERRATIC WINDS. CEILINGS COULD POTENTIALLY LOWER TO 8 KFT
AT TIMES.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...SCATTERED-ISOLATED SHRA/TSRA WILL BE POSSIBLE THROUGH
THIS EVENING PRIMARILY SOUTH OF KLAS. GUSTY AND ERRATIC WINDS WILL
BE POSSIBLE IN AND NEAR ANY SHRA/TSRA. OTHERWISE RELATIVELY LIGHT
WINDS WILL FAVOR TYPICAL DIURNAL TRENDS. EXPECT SCT-BKN CLOUDS AOA
7K-12K FEET AS WELL SOUTH OF LAS VEGAS. AREAS OF FU AND HZ ARE
POSSIBLE IN AROUND KBIH REDUCING VSBY AND CREATING LOCALIZED
MOUNTAIN OBSCURATIONS. MOST OF THE AREA WILL BE FREE OF
THUNDERSTORMS FRIDAY WITH AREAS SOUTH OF LAS VEGAS SEEING A CHANCE
OF STORMS AGAIN SATURDAY. MOISTURE AND THUNDERSTORM COVERAGE WILL
INCREASE ACROSS THE ENTIRE AREA SUNDAY.
&&

.SPOTTER INFORMATION STATEMENT...SPOTTERS ARE ENCOURAGED TO REPORT
ANY SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING
PROCEDURES.
&&

HARRISON

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