Area Forecast Discussion
Issued by NWS Las Vegas, NV

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000
FXUS65 KVEF 221543 AAA
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
843 AM PDT TUE JUL 22 2014

.SYNOPSIS...DRY SOUTHWEST FLOW WITH SEASONABLE TEMPERATURES CAN BE
EXPECTED TODAY. THE FLOW WILL BECOME MORE SOUTHERLY BY WEDNESDAY
LEADING TO AN INCREASE IN CLOUDS OVER WESTERN ARIZONA AND A SLIGHT
CHANCE OF THUNDERSTORMS OVER THE HIGHER TERRAIN THERE. HOT
CONDITIONS ARE STILL EXPECTED TO DEVELOP ACROSS THE AREA DURING THE
SECOND HALF OF THE WEEK AS HIGH PRESSURE EXPANDS OVER THE DESERT
SOUTHWEST.
&&

.UPDATE...HIGH CENTER NEAR EL PASO THIS MORNING WITH MORNING
ANALYSIS SHOWING AN INVERTED TROUGH BETWEEN EL PASO AND TUCSON
EXTENDING SOUTH INTO NORTHWEST MEXICO. EASTERLY FLOW ACROSS SOUTHERN
ARIZONA HAS BROUGHT PRECIP. WATER VALUES BACK ABOVE 1 INCH AT
PHOENIX AND TUCSON. MODELS STILL SHOWING SOME OF THIS MOISTURE
SPREADING WESTWARD INTO NORTHWEST ARIZONA AND POSSIBLY AS FAR WEST
AS EASTERN SAN BERNARDINO COUNTY AND CLARK COUNTIES BEFORE
ENCOUNTERING A DRIER SOUTHWESTERLY FLOW. NO UPDATED NEEDED THIS
MORNING. FOR THE AFTERNOON PACKAGE, WILL CONTINUE TO LOOK AT
THUNDERSTORM CHANCES FOR NORTHWEST ARIZONA IN THE COMING DAYS AS
WELL AS HIGH TEMPERATURES AREA WIDE FOR THE REST OF THE WEEK.
&&

.SHORT TERM...THROUGH THURSDAY NIGHT...EXPANDING AREA OF HIGH
PRESSURE OVER THE DESERT SOUTHWEST WILL LEAD TO CONTINUED WARMING
AND MAINLY DRY CONDITIONS. TEMPERATURES WILL WARM A DEGREE OR TWO
EACH DAY THROUGH THE SHORT TERM WITH HIGH TEMPERATURES BY THURSDAY
ABOUT FIVE DEGREES ABOVE NORMAL AND JUST A COUPLE OF DEGREES SHY OF
EXCESSIVE HEAT WARNING CRITERIA. THE ENTIRE FORECAST AREA LOOKS TO
REMAIN PRETTY STABLE TODAY WITH PRECIPITABLE WATER VALUES BEGINNING
TO CREEP UP OVER SOUTHERN MOHAVE COUNTY LATE IN THE DAY. A WEAK
SHORTWAVE IS PROGGED TO MOVE NORTH INTO WESTERN ARIZONA TONIGHT
WHICH WILL BRING SOME ADDITIONAL INCREASE IN MOISTURE INTO MOHAVE
COUNTY BY WEDNESDAY. THE MODELS INDICATE SOME WEAK INSTABILITY OVER
THE EASTERN HALF OF MOHAVE COUNTY AND JUST ENOUGH MOISTURE FOR A
SLIGHT CHANCE OF THUNDERSTORMS OVER SOME OF THE HIGHER TERRAIN. I
KEPT A SLIGHT CHANCE MENTIONED FOR THURSDAY AFTERNOON AS THE NAM12
KEEPS SOME MOISTURE AND INSTABILITY IN PLACE. ALL THE MODELS ARE IN
AGREEMENT THAT OUTSIDE OF EASTERN MOHAVE COUNTY...THE CWA WILL
REMAIN DRY AND STABLE THROUGH THURSDAY NIGHT.

.LONG TERM...FRIDAY THROUGH TUESDAY...TWO PRIMARY ITEMS OF INTEREST
IN THE EXTENDED PERIOD ARE THE HEAT AND THE RETURN OF SOME MONSOON
MOISTURE. BY FRIDAY AFTERNOON...BROAD SUBTROPICAL RIDGE WILL STRETCH
FROM SOUTHERN CALIFORNIA ALL THE WAY EAST TO THE SOUTHERN PLAINS,
WITH THE RIDGE CENTERED NEAR THE FOUR CORNERS. THIS WILL KEEP THE
HEAT FIRMLY ENTRENCHED ACROSS THE SOUTHWEST FRIDAY AND SATURDAY.
LATEST ECMWF GUIDANCE HAS TRENDED SLIGHTLY COOLER WITH THE EXTENDED
PERIOD TEMPS COMPARED TO LAST NIGHTS RUN WHILE GFS MAINTAINS WARM
(BUT COOLER THAN THE ECMWF) TEMPERATURES. THEREFORE I KEPT FRIDAY AS
THE HOTTEST DAY AND COOLED TEMPERATURES DOWN VERY SLIGHTLY ON
SATURDAY DUE TO THE POSSIBILITY OF SOME ADDED HIGH CLOUD COVER
BEGINNING TO WRAP AROUND THE HIGH.

ON SUNDAY...MODELS APPEAR TO BE KEYING IN ON THE LIKELIHOOD OF AN
INVERTED TROUGH WORKING AROUND THE BASE OF THE HIGH AND PUSHING WEST
TOWARDS THE MOJAVE DESERT ON SUNDAY. THIS WOULD RESULT IN A MARKED
INCREASE IN CLOUD COVER AND INCREASED COVERAGE OF AFTERNOON AND
EVENING CONVECTION. THIS TROUGH WILL CONTINUE TO PUSH EAST ALONG THE
SIERRA CREST AND INTO CENTRAL CALIFORNIA EARLY NEXT WEEK WITH
THUNDER CHANCES EXPANDING WESTWARD. TRENDED TEMPERATURES CLOSER TO
CLIMATOLOGY FROM SUNDAY ONWARD WITH POPS STILL PRIMARILY LIMITED TO
MOUNTAIN ZONES.  HOWEVER, IF MODEL AGREEMENT CONTINUES TO INCREASE
WE MAY NEED TO INCREASE THUNDERSTORM COVERAGE FURTHER DOWN THE ROAD.
&&

.AVIATION...FOR MCCARRAN...SOUTH WINDS NEAR 10 KTS CAN BE EXPECTED
THROUGH EARLY THIS MORNING. WINDS WILL GO EASTERLY BY LATE THIS
MORNING WITH SPEEDS BETWEEN 5-9 KTS. THE WIND SHOULD SHIFT MORE
SOUTHERLY BY LATE AFTERNOON OR EARLY EVENING. SKIES WILL BE MOSTLY
CLEAR THROUGH TONIGHT.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...NO SIGNIFICANT WEATHER AFFECTING TERMINALS THROUGH
TONIGHT. STRONGEST SURFACE WINDS TODAY WILL OCCUR IN THE OWENS
VALLEY WHERE SOUTH WINDS OF 10-20 KTS WITH GUSTS TO 25 KTS ARE
POSSIBLE.
&&

.SPOTTER INFORMATION STATEMENT...SPOTTER ACTIVATION IS NOT EXPECTED
AT THIS TIME. HOWEVER...SPOTTERS ARE ENCOURAGED TO REPORT ANY
SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING
PROCEDURES.
&&

$$

UPDATE...PIERCE
SHORT TERM/AVIATION...HARRISON
LONG TERM...OUTLER

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