Area Forecast Discussion
Issued by NWS Las Vegas, NV

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000
FXUS65 KVEF 140349 AAA
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
848 PM PDT SUN JUL 13 2014

.SYNOPSIS...MOISTURE WILL SPREAD BACK INTO NORTHWEST ARIZONA TODAY
LEADING TO A CHANCE OF AFTERNOON AND EVENING THUNDERSTORMS. A MOIST
SOUTHEAST FLOW WILL INCREASE OVER THE ENTIRE REGION MONDAY AND
TUESDAY WITH EXPANDING THUNDERSTORM COVERAGE. TEMPERATURES WILL ALSO
TREND COOLER WITH INCREASING MOISTURE.
&&

.UPDATE...THUNDERSTORMS FROM LATE AFTERNOON OVER MOHAVE COUNTY HAVE
WORKED WEST INTO THE THE LAKE MEAD NATL RECREATION AREA AND LOWER
COLORADO RIVER VALLEY. NOW WE ARE MONITORING OUTFLOW WINDS AND
STARTING TO SEE NEW DEVELOPMENT SPREAD WEST TOWARD SEARCHLIGHT AS
WELL AS SEEING SOME NEW TOWERS GO UP ON THE EAST SIDE OF THE SPRING
MTNS. SO FAR STORM MOTION FAST ENOUGH THAT WE ARE NOT WORRIED ABOUT
FLASH FLOODING, BUT MORE WORRIED ABOUT STRONG WINDS. MOIST EASTERLY
FLOW PROGGED TO CONTINUE OVERNIGHT WITH AN ISOLATED SHOWER OR
THUNDERSTORM POSSIBLE WELL INTO MONDAY MORNING FOR THE MOJAVE
DESERT. THIS IS COVERED IN THE CURRENT PACKAGE SO NO UPDATE NEEDED AT
THIS TIME.
&&

.AVIATION...FOR MCCARRAN...OUTFLOW FROM NEARBY SHOWERS AND
THUNDERSTORMS WILL LIKELY KEEP A SOUTHEAST WIND DIRECTION PROBABLY
THROUGH MIDNIGHT. SUSTAINED WINDS WILL BE AROUND 15 KTS WITH GUSTS
TO 25 KTS. ISOLATED SHOWERS AND THUNDERSTORMS WILL IMPACT ALL
APPROACH CORRIDORS OVERNIGHT. ISOLATED THUNDERSTORMS WILL RETURN TO
THE TERMINAL AREA MONDAY AS A MOIST SOUTHEAST FLOW REDEVELOPS.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...ISOLATED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE THE
REST OF TONIGHT OVER THE MOJAVE DESERT AND SOUTHEAST NEVADA.
GUSTY WINDS AND BRIEF HEAVY RAIN WILL ACCOMPANY THE STORMS.
AN INCREASINGLY EAST TO SOUTHEAST FLOW WILL CONTINUE THROUGH EARLY
IN THE WEEK WITH THUNDERSTORM COVERAGE EXPANDING ACCORDINGLY.
&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
SOME MIDLEVEL CLOUDS ARE STREAMING EAST-NORTHEAST TO WEST-SOUTHWEST
ACROSS CENTRAL AND SOUTHERN MOHAVE COUNTY. CANNOT RULE OUT A LIGHT
SHOWER/SPRINKLE WITH THESE CLOUDS...BUT THE MAIN PRECIP WILL
ORIGINATE WITH CONVECTION THAT IS FORECAST TO DEVELOP IN ITS WAKE OR
ON THE NORTHERN PERIPHERY. CUMULUS DEVELOPMENT IS EVIDENT ACROSS
NORTHERN MOHAVE AND LINCOLN COUNTIES. ALSO SEE RADAR RETURNS
INCREASING ACROSS SOUTHWEST UT AND CENTRAL AZ.

LOCAL AND NATIONAL HIRES MODELS ARE IN FAIRLY GOOD AGREEMENT THAT
CONVECTION WILL DEVELOP ACROSS MOHAVE COUNTY AND PUSH
WEST-SOUTHWEST. GIVE THE EFFECTIVE AND 0-6 KM BULK SHEAR DIRECTIONS
AND VALUES OF GENERALLY 20-35 KNOTS...AM LEANING TOWARD THOSE HIRES
SOLUTIONS FOR TONIGHT. THIS HIRES CONSENSUS PUSHES CONVECTION IN A
WEAKENING STATE INTO EASTERN SAN BERN AND EASTERN CLARK COUNTIES AS
WELL AS AN OUTFLOW THROUGH THE LAS VEGAS VALLEY LATER THIS EVENING.
THIS WOULD INCREASE LOW-LEVEL MOISTURE AND SET THE STAGE FOR
TOMORROW...WHERE I HAVE INCREASED POPS ACROSS MUCH OF THE FORECAST
AREA. CONVECTION SHOULD DEVELOP AGAIN TO OUR EAST MONDAY AS WELL AS
THE HIGHER TERRAIN AROUND LAS VEGAS. ANY OUTFLOW FROM THE EASTERN
COMPLEX OF STORMS SHOULD TRIGGER MORE CONVECTION AROUND THE VEGAS
VALLEY...IF WE GET THAT MOISTURE PUSH LATER TONIGHT. WE SHOULD ALSO
SEE CONVECTION ALONG THE SOUTHERN SIERRA AND WHITE MOUNTAINS...AS
THE INVERTED TROUGH CURRENTLY ACROSS NORTHERN MEXICO PUSHES
WEST-NORTHWEST INTO CA.

FOR TUESDAY...NOT REALLY SEEING A TRIGGER MECHANISM FOR ORGANIZED
CONVECTION. SO...THE REGION SHOULD SEE MORE OROGRAPHIC DRIVEN
CONVECTION INITIALLY FOLLOWED BY OUTFLOW BOUNDARY INTERACTION DURING
THE AFTERNOON AND EVENING HOURS. IF THE LAS VEGAS VALLEY DOES
EXPERIENCE AN ACTIVE DAY TOMORROW...THEN WOULD EXPECT MORE OF A DOWN
DAY TUESDAY. TEMPERATURES WILL TREND COOLER THROUGH THE SHORT TERM
PERIOD WITH INCREASING MOISTURE.

.LONG TERM...WEDNESDAY THROUGH SUNDAY...TWO WEAK UPPER LEVEL
DISTURBANCES WILL BE INFLUENCING OUR WEATHER ON WEDNESDAY. THE FIRST
WILL BE MOVING SOUTHEAST DOWN THE FRONT RANGE WHILE THE SECOND WILL
BE MOVING TO THE NORTHWEST OFF OF THE CALIFORNIA COAST. THOSE TWO
SYSTEMS WILL BE INFLUENCING WHERE THE MOISTURE BOUNDARY WILL BE. AT
THIS POINT DRIER AIR WILL BE MOVING INTO SOUTHEAST CALIFORNIA...BUT
REMAIN IN PLACE ACROSS MUCH OF SOUTHERN NEVADA AND NORTHWEST
ARIZONA. BY THURSDAY...THE DRIER AIR WILL NOSE A LITTLE FURTHER TO
THE NORTH AND THUNDERSTORMS CHANCE WILL DIMINISH MODESTLY IN MOST
LOCATIONS. BY FRIDAY WEAK RIDGING WILL BE IN PLACE AND THE DRYING
TREND WILL CONTINUE...LIMITING THE THUNDERSTORMS FURTHER AND
PRIMARILY OVER THE HIGH TERRAIN. SATURDAY LOOKS TO BE THE QUIETEST
DAY OF THE PERIOD AT THIS POINT AS THE RIDGE OF HIGH PRESSURE SLOWLY
SHIFTS TO THE EAST...BEING CENTERED OVER THE FOUR CORNERS REGION
SATURDAY AFTERNOON. BOTH THE GFS AND ECMWF INDICATE THE RIDGE
DROPPING FURTHER SOUTH AND EAST...SETTING THE STAGE FOR ANOTHER
RETURN OF MONSOON MOISTURE ON ON SUNDAY AND THE FLOW SHIFT TO THE
SOUTHEAST. TEMPERATURES WILL BE FAIRLY FLAT THROUGH THE PERIOD AND
WITHIN A COUPLE OF DEGREES OF THEIR SEASONAL NORMS.
&&

.SPOTTER INFORMATION STATEMENT...SPOTTER ACTIVATION IS NOT EXPECTED
TONIGHT. SPOTTER ACTIVATION MAY BE REQUESTED MONDAY OR TUESDAY.
HOWEVER, SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
&&

$$

UPDATE...PIERCE
SHORT TERM/AVIATION...PADDOCK
LONG TERM...CZYZYK

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