Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 050329
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
829 PM PDT FRI SEP 4 2015

.SYNOPSIS...A STORM SYSTEM MOVING ACROSS THE PACIFIC NORTHWEST WILL
PASS ACROSS NEVADA ON SATURDAY RESULTING IN ANOTHER DAY OF GUSTY
WINDS. TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH THE WEEKEND
THEN WARM BACK TO NEAR NORMAL BY THE MIDDLE OF NEXT WEEK.
PRECIPITATION CHANCES MAY RETURN TO PORTIONS OF THE REGION NEXT
WEEK.
&&

.UPDATE...CURRENTLY MOST OF THE CONVECTION APPEARS TO BE ON A
DOWNWARD TREND, HOWEVER, WEAK ACTIVITY WAS STILL HANGING ON IN FAR
EASTERN LINCOLN COUNTY. AN OUTFLOW BOUNDARY WAS ALSO WORKING
NORTHWEST ACROSS SOUTHERN MOHAVE COUNTY TOWARD LAKE HAVASU. AS WAS
THE CASE LAST EVENING, WE PROBABLY WILL SEE AN HOUR OR TWO OF GUSTS
OF 20-30 MPH AS THIS BOUNDARY MOVES THROUGH. ALTHOUGH THERE WAS
LITTLE IN THE WAY OF PRECIPITATION BEHIND THIS BOUNDARY, A FEW
LIGHTNING STRIKES WERE DETECTED. THE GRIDS WERE TWEAKED FOR WINDS,
SKY COVER AND POPS.

THE RED FLAG WARNINGS HAVE ALSO BEEN ALLOWED TO EXPIRE AS WELL AS
THE WIND ADVISORIES THAT WERE IN EFFECT FOR TODAY IN THE SOUTHERN
GREAT BASIN AS WINDS HAVE DECREASED AND DROPPED BELOW 40 MPH IN
LINCOLN, ESMERALDA AND CENTRAL NYE COUNTIES.

THE REST OF THE FORECAST LOOKS GOOD AT THIS TIME.
&&

.AVIATION...FOR MCCARRAN...SOUTH TO SOUTHWEST WINDS WILL REMAIN
GUSTY EARLY OVER 15 KTS BUT SLOWLY DECREASE AS THE EVENING MOVES
ALONG. WINDS WILL AGAIN INCREASE LATE SATURDAY MORNING AND BE
STRONGEST IN THE AFTERNOON AND EARLY EVENING GUSTING OVER 20 KTS.
THERE IS A SMALL WINDOW BETWEEN 14Z AND 17Z WHERE WIND DIRECTION
WILL BE NEAR THE 160 DEGREE LINE WHICH MAY CAUSE CONFIGURATION
ISSUES.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...GUSTY SOUTH TO SOUTHWEST WINDS WILL CONTINUE TO
DECREASE THIS EVENING. TURBULENCE IS POSSIBLE THROUGH TOMORROW
AFTERNOON DUE TO INCREASING WINDS WITH HEIGHT. ISOLATED SHRA AND
TSRA REMAIN POSSIBLE THIS EVENING MAINLY EAST OF A KELY-KEED LINE
WITH DRY CONDITIONS ELSEWHERE. THERE WILL AGAIN BE THE POSSIBILITY
OF A SHRA/TSRA ON SATURDAY AFTER 18Z AND BEFORE 06Z SUNDAY IN AND
AROUND MT TRUMBILL. ALL OTHER AREAS SHOULD BE DRY.
&&

.DISCUSSION...THROUGH THURSDAY.

THE SYNOPTIC SETTING THIS AFTERNOON FEATURES A HIGHLY AMPLIFIED
PATTERN. A STRONG UPPER LOW IS POSITIONED OVER THE PACIFIC
NORTHWEST, WHILE RIDGING IS IN CONTROL ACROSS THE EASTERN HALF OF
THE CONUS. THE STRONG UPPER LOW IS RESPONSIBLE FOR THE GUSTY WINDS
AND DRY SOUTHWEST FLOW ACROSS MUCH OF THE FORECAST AREA. A
CONTINUATION OF THE WIND ADVISORY FOR LINCOLN, NORTHEAST CLARK, AND
NORTHERN MOHAVE COUNTIES REMAINS FOR TOMORROW.

SHOWER/STORM CHANCES GREATLY DIMINISH TOMORROW AS THE TROUGH AXIS
SHIFTS EAST AND DRY SOUTHWEST FLOW TAKES CONTROL OF OUR EASTERN
FORECAST AREA. BY SUNDAY THE SHORTWAVE TROUGH AXIS WILL BE WELL EAST
AND WINDS WILL BE NOTICEABLY LIGHTER. A WEAK LONGWAVE TROUGH WILL
REMAIN ACROSS THE WESTERN CONUS, KEEPING A DRY SOUTHWEST FLOW OVER
THE FORECAST AREA. THE 12Z RUNS OF THE GFS, GEFS, NAM, AND SREF SHOW
A SLIGHT INCREASE IN MID-LEVEL MOISTURE ACROSS NORTHERN ARIZONA. THE
GFS SHOWS SOME OF THAT WORKING WEST INTO EASTERN MOHAVE COUNTY WITH
A SLIGHT CHANCE OF PRECIPITATION. FOR NOW HAVE KEPT THE FORECAST
DRY, BUT WILL HAVE TO MONITOR MOISTURE AND INSTABILITY TRENDS OVER
THE NEXT 24 HOURS. AS FOR TEMPERATURES THROUGH SUNDAY, EXPECT A FEW
DEGREES OF COOLING FOR SATURDAY WITH NEARLY THE SAME CONDITIONS FOR
SUNDAY.

THERE IS GENERAL AGREEMENT THAT THE WEST COAST TROUGHING WILL BREAK
DOWN AS A SHORTWAVE TROUGH PUSHES EAST ACROSS THE PACIFIC NORTHWEST
ON MONDAY. THIS WILL ALLOW HIGH PRESSURE AND WARMER TEMPERATURES TO
BUILD BACK INTO THE REGION AS THE WEEK PROGRESSES. HOWEVER, THE
FORECAST DETAILS FOR NEXT WEEK CONTINUE TO HAVE LOW CONFIDENCE.
THERE COULD BE LINGERING SHOWER/STORM CHANCES MAINLY IN MOHAVE
COUNTY ON MONDAY AND TUESDAY, BUT THAT IS ONLY IF THE GFS IS CORRECT
WITH DEVELOPMENT ON SUNDAY. THE GFS KEEPS SOME MID-LEVEL MOISTURE
AROUND AND ANY PRECIP ON SUNDAY WOULD ADD TO LOW-LEVEL MOISTURE. THE
12Z NAEFS DATA SUGGEST LESS OF A CHANCE, BUT THERE IS SPREAD IN THE
SOLUTIONS. THE GFS THEN DRIES OUT THE FORECAST AREA HEADING INTO THE
MIDDLE OF THE WEEK. MEANWHILE, THE ECMWF KEEPS OUR AREA DRY THROUGH
TUESDAY BEFORE BRINGING A MOISTURE PLUME NORTHWARD TOWARD THE DESERT
SOUTHWEST FROM A NEW TROPICAL DISTURBANCE IN THE EASTERN PACIFIC.
THE 12Z NAEFS IS MORE IN LINE WITH THE ECMWF SOLUTION, SHOWING THIS
PLUME OF MOISTURE. GIVEN THE UNCERTAINTY, WILL CONTINUE NO MENTION
OF SHOWERS OR STORMS IN THE FORECAST, BUT DID INCREASE POPS ACROSS
AREAS THAT MAY NEED TO BE FURTHER INCREASED IN FUTURE FORECASTS ONCE
DETAILS CONVERGE TOWARD A COMMON SOLUTION. WITH HIGH PRESSURE
BUILDING OVERHEAD, TEMPERATURES WILL CLIMB TO NEAR NORMAL VALUES.
&&

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

$$

UPDATE/AVIATION...STACHELSKI
DISCUSSION...PADDOCK

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