Area Forecast Discussion
Issued by NWS Las Vegas, NV

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000
FXUS65 KVEF 031648
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
948 AM PDT THU SEP 3 2015

.SYNOPSIS...A STORM SYSTEM WILL PUSH ACROSS THE PACIFIC NORTHWEST AS
WELL AS NORTHERN PORTIONS OF CALIFORNIA AND NEVADA THROUGH SATURDAY
RESULTING IN GUSTY SOUTH TO SOUTHWEST WINDS ACROSS THE AREA
ESPECIALLY IN THE AFTERNOON AND EVENING. TEMPERATURES WILL REMAIN
BELOW NORMAL THROUGH THE WEEKEND. TEMPERATURES WILL RISE BACK TO
NEAR NORMAL ALONG WITH DRY CONDITIONS THROUGH THE MIDDLE OF NEXT
WEEK.
&&

.UPDATE...DRY SOUTHWEST FLOW CONTINUES ACROSS THE AREA WITH PW
VALUES LOWERING IN MOST LOCATIONS A TENTH OR TWO. A BAND OF CLOUDS
OVER NYE COUNTY ARE PUSHING TO THE EAST AND INTO LINCOLN COUNTY AND
UPDATED THE FORECAST TO ACCOUNT FOR THOSE. THE REST OF THE FORECAST
LOOKS ON TRACK. WINDS HAVE BEGUN TO KICK IN ACROSS MUCH OF THE AREA
WITH THE STRONGEST WINDS EXPECTED IN NYE COUNTY. EXPECT A FEW
LOCATIONS TO BE NEAR OR REACH WIND ADVISORY LEVELS BUT THOSE SHOULD
BE FAIRLY ISOLATED. THERE IS POTENTIAL FOR MODESTLY STRONGER WINDS
TOMORROW ACROSS MUCH OF SOUTHERN NEVADA AND WILL BE EVALUATING THE
NEED FOR WIND ADVISORIES.
&&

.AVIATION...FOR MCCARRAN...WINDS APPEAR TO FAVOR A 170-220 DEGREES
TRUE DIRECTION COMPONENT TODAY WITH SPEEDS PICKING UP BETWEEN 17Z
AND 20Z. GUSTS OVER 25 KTS ARE POSSIBLE IN THE AFTERNOON AND EARLY
EVENING. GUSTY SOUTH TO SOUTHWESTERLY WINDS WILL PREVAIL THROUGH
SATURDAY ALONG WITH VARIABLE CLOUDS AOA 25K FEET.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...SOUTHERLY WINDS WITH AFTERNOON AND EVENING GUSTS OF 20-
30 KTS ARE EXPECTED THROUGH SATURDAY. VARIABLE AMOUNTS OF CLOUDS
MAINLY AOA 25K FEET.
&&

.PREVIOUS DISCUSSION...
ISSUED AT 301 AM PDT THU SEP 3 2015

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT.

SATELLITE LOOPS SHOW A BATCH OF MAINLY HIGH-LEVEL CLOUDS MOVING
NORTH-NORTHEAST ACROSS MOHAVE...CLARK AND EASTERN SAN BERNARDINO
COUNTIES EARLY THIS MORNING. MOST OF THESE SHOULD START TO EXIT TO
THE EAST BY LATER THIS MORNING BUT SHOULD LAST LONG ENOUGH ACROSS
MOHAVE AND EASTERN LINCOLN COUNTY THAT CLOUD COVER WAS ADJUSTED UP
IN THOSE AREAS TO START THE DAY. BY THIS AFTERNOON, MODEL CROSS
SECTIONS SHOW A DECREASE IN MOISTURE ABOUT 500 MB WHICH SHOULD
RESULT IN RELATIVELY SUNNY CONDITIONS FOR THIS AFTERNOON.

HIGH TEMPERATURES ACROSS THE LAS VEGAS FORECAST/WARNING AREA
YESTERDAY RANGED FROM 56 AT THE HADS MESONET STATION NEAR BIG PINE
CREEK AT 10000 FEET TO 110 DEGREES AT THE CO-OP STATION AT FURNACE
CREEK IN DEATH VALLEY NATIONAL PARK. THE WATER VAPOR LOOP SHOWS AN
UPPER-LEVEL LOW SPINNING OVER THE SOUTHERN END OF VANCOUVER ISLAND.
THIS LOW HAS HELPED CARVE OUT A TROUGH ALOFT ACROSS THE WEST THAT
WILL CONTINUE TO DEEPEN THROUGH THE DAY AS LOW DROPS SOUTH INTO
WESTERN WASHINGTON. AS A RESULT...500 MB HEIGHTS ARE FORECAST TO
DROP FROM 5850 METERS YESTERDAY EVENING TO 5790 METERS BY THIS
AFTERNOON. THIS WILL RESULT IN A FEW DEGREES OF COOLING TODAY ACROSS
ALL AREAS. HOWEVER...GIVEN A BLEND OF THE BETTER PERFORMING
GUIDANCE...FORECASTED HIGH TEMPERATURES TODAY LEAN TOWARD THE WARMER
END OF GUIDANCE.

THE PRIMARY CONCERN TODAY WILL AGAIN BE GUSTY WINDS AND LOW RELATIVE
HUMIDITY VALUES. GIVEN THE CORE OF THE JET STILL REMAINS WELL TO OUR
NORTH...WIND GUSTS TODAY ARE EXPECTED TO MAINLY BE IN THE 25-35 MPH
RANGE THIS AFTERNOON AND EVENING WITH THE HIGHEST SPEEDS IN THE
SOUTHERN GREAT BASIN. SEE THE FIRE WEATHER SECTION BELOW FOR MORE.

THE UPPER LEVEL TROUGH IS FORECAST TO DEEPEN FURTHER ON FRIDAY WITH
THE AXIS OF THE TROUGH MOVING ACROSS THE AREA SATURDAY MORNING INTO
SATURDAY AFTERNOON. ALTHOUGH WINDS WILL SLOWLY DROP OFF EACH
NIGHT...THEY WILL INCREASE AGAIN IN THE LATE MORNING INTO THE
AFTERNOON. THE WINDIEST DAY ACROSS THE AREA IS EXPECTED TO BE ON
FRIDAY AS UPPER LEVEL SUPPORT INCREASES. THE GFS AND ECMWF BOTH SHOW
700 MB WINDS INCREASING TO 30-35 KTS ACROSS MUCH OF THE AREA AND
SHOW WELL ALIGNED WINDFIELDS AT 850 MB WHICH WILL PROMOTE THE
STRONGER WINDS ALOFT MIXING DOWN TO THE SURFACE. THIS WILL SUPPORT
GUSTS OF 35-45 MPH IN MANY AREAS ESPECIALLY NORTH OF INTERSTATE 40.
A CLOSER LOOK AT THE ARW AND NMM MODELS SHOW A CRITICAL LAYER
DEVELOPING TO THE LEE OF THE SOUTHERN SIERRA AS WELL AS THE SPRING
MOUNTAINS WHICH WOULD FAVOR DOWNSLOPE WINDS DEVELOPING WHICH COULD
LEAD TO LOCALLY HIGHER GUSTS. WIND ADVISORIES MAY BE NEEDED FRIDAY
FOR LINCOLN COUNTY...CENTRAL AND SOUTHERN NYE COUNTY AND THE SPRING
MOUNTAINS. WINDS SHOULD START TO DECREASE SATURDAY EVENING AS THE
UPPER LEVEL SUPPORT BEGINS TO WEAKEN.

THERE WILL ALSO BE THE CHANCE FOR ISOLATED THUNDERSTORMS ON FRIDAY
ACROSS THE HIGHER TERRAIN OF EASTERN MOHAVE COUNTY AS 700-500 MB
MOISTURE SHOWS AN INCREASE AS SOUTHERLY FLOW INCREASES AHEAD OF THE
TROUGH AXIS. THE 00Z RUN OF THE ECMWF MODEL WAS THE ONLY MODEL TO
GENERATE QPF IN THIS AREA IN THE FRIDAY AFTERNOON INTO FRIDAY
EVENING TIME FRAME /AROUND 00Z SATURDAY ON THE MODEL/.

TEMPERATURES WILL CONTINUE TO DROP A FEW DEGREES EACH DAY THROUGH
SATURDAY. THE COOLEST NIGHT WILL BE SATURDAY NIGHT WHEN EVEN
MCCARRAN AIRPORT LOOKS TO DROP DOWN TO 70 DEGREES. THIS WILL PLUNGE
MUCH OF THE LAS VEGAS VALLEY INTO THE 60S FOR LOWS.

.LONG TERM...SUNDAY THROUGH THURSDAY.

THE LATEST OPERATIONAL MODEL GUIDANCE IS IN GOOD AGREEMENT IN THE
LONG TERM PERIOD BEGINNING WITH A BROAD TROUGH ACROSS THE GREAT
BASIN AND MOJAVE DESERT...YIELDING DRIER AIR...BREEZY CONDITIONS AND
SEASONAL TEMPERATURES. THE LATEST GFS SOLUTIONS ARE BEGINNING TO
TREND SOMEWHAT TOWARD THE ECMWF...HOWEVER NOTABLE DIFFERENCES WILL
CONTINUE TO KEEP FORECAST CONFIDENCE ON THE CAUTIOUS SIDE TONIGHT.
IT IS NOTED THAT THE GFS HAS BEEN RATHER AGGRESSIVE IN BRINGING
MOISTURE BACK INTO EASTERN ZONES EARLY NEXT WEEK. WITH WESTERLY FLOW
LOOKING TO DOMINATE THE OVERALL PATTERN INTO NEXT WEEK...IT APPEARS
MORE LIKELY THAT SIGNIFICANT MOISTURE WILL BE EAST OF THE FORECAST
AREA. DECIDED TO LEAN MORE HEAVILY ON THE ECMWF SOLUTION THIS
EVENING...KEEPING THE LONG TERM PERIOD DRY AS A RESULT.

AS FOR THE DIFFERENCES REGARDING THE OVERALL PATTERN...THE GFS AND
ECMWF BOTH DEPICT A SECONDARY OPEN WAVE DIVING DOWN ACROSS THE
NORTHERN GREAT BASIN DURING THE MONDAY-TUESDAY TIMEFRAME...WITH THE
GFS DEPICTING A MORE AMPLIFIED/LESS PROGRESSIVE WAVE. IMPACTS LOOK
TO BE FAIRLY MINIMAL WITH THIS POTENTIAL FEATURE AT THIS TIME...WITH
GUSTY WINDS LOOKING TO BE THE MAIN RESULTANT WEATHER MONDAY-TUESDAY.
BY MID TO LATE WEEK...GUIDANCE HINTS AT THE SUBTROPICAL HIGH
MIGRATING BACK TO THE WEST. THE STRENGTH OF THE HIGH WILL DEPEND ON
IF THERE ARE ANY ADDITIONAL SHORTWAVES DIVING DOWN ACROSS THE
PACIFIC NORTHWEST AND NORTHERN GREAT BASIN. THIS WOULD EFFECTIVELY
KEEP ANY ASSOCIATED RIDGING WITH THE HIGH FAIRLY FLAT AND MITIGATE
THE WARMING OF AFTERNOON HIGHS FOR THE LATTER PART OF THE WEEK. THIS
WILL BE SOMETHING TO KEEP AN EYE ON...AS MODELS CONTINUE TO ATTEMPT
TO CONVERGE ON A COMMON SOLUTION FOR THIS PERIOD IN THE COMING DAYS.
&&

.FIRE WEATHER...CRITICAL FIRE WEATHER CONDITIONS EXPECTED ACROSS NYE
AND ESMERALDA COUNTIES THROUGH FRIDAY DUE TO THE COLLOCATION OF DRY
FUELS...LOW MINIMUM RELATIVE HUMIDITY VALUES...AND WINDS OF 20-25
MPH WITH GUSTS OF 35 TO 40 MPH. A RED FLAG WARNING IS IN EFFECT
THROUGH FRIDAY. CRITICAL FIRE WEATHER MAY DEVELOP ACROSS PARTS OF
INYO COUNTY THROUGH THIS AFTERNOON BUT THE DURATION LOOKS TO REMAIN
BRIEF AND BELOW CRITERIA. GUSTY CONDITIONS ALSO EXPECTED IN THE
SPRING AND SHEEP RANGE BUT MINIMUM RELATIVE HUMIDITY VALUES WILL
STAY ABOVE 15 PERCENT...BUT BEARS WATCHING FRIDAY AS DRIER AIR
FILTERS IN.
&&

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

$$

UPDATE...CZYZYK
SHORT TERM/AVIATION/FIRE WEATHER...STACHELSKI
LONG TERM...PULLIN

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