Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 212314
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
314 PM PST FRI NOV 21 2014

.SYNOPSIS...A COLD FRONT WILL MOVE ACROSS THE AREA SATURDAY EVENING
THROUGH EARLY SUNDAY MORNING. THIS WILL RESULT IN GUSTY WEST TO
SOUTHWEST WINDS AHEAD OF THE FRONT ON SATURDAY AND GUSTY NORTH WINDS
BEHIND THE FRONT ON SUNDAY. OUTSIDE OF A FEW SNOW SHOWERS IN THE
SOUTHERN SIERRA NEVADA...MAINLY NEAR THE CREST...AND A FEW RAIN AND
SNOW SHOWERS IN FAR NORTHERN LINCOLN COUNTY THIS FRONT WILL PASS THE
AREA DRY. DRY CONDITIONS WITH NEAR SEASONABLE TEMPERATURES ARE
EXPECTED ACROSS THE AREA THROUGH THANKSGIVING DAY.
&&

.SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT.

AS QUICKLY AS ONE SYSTEM HAS EXITED THE AREA ANOTHER SYSTEM IS ABOUT
TO ENTER THE PICTURE. SATELLITE IMAGERY SHOWS PLENTY OF HIGH LEVEL
CLOUDS STARTING TO PUSH ACROSS NORTHERN NEVADA THIS AFTERNOON AND
THESE WILL SPILL SOUTHEAST TONIGHT ON THE LEADING EDGE OF THE NEXT
JET STREAK. THUS EXPECT A PARTLY TO MOSTLY CLOUDY SKY TONIGHT WITH
LOWS A TOUCH HIGHER THAN WHAT WE SAW THIS MORNING.

THE NEXT MID/UPPER LEVEL SHORTWAVE TROUGH IS EXPECTED TO MOVE
SOUTHEAST ACROSS NEVADA TOMORROW AFTERNOON INTO TOMORROW NIGHT
ACCOMPANIED BY A FULL-FLEDGED COLD FRONT PASSAGE AT THE SURFACE. A
POWERHOUSE JET SHOWN BY THE GFS TO EXCEED 160 KTS OVER NORTHEAST
NEVADA AT 250 MB WILL ACCOMPANY THIS TROUGH, HOWEVER, MODELS FAIL TO
REALLY ALIGN THE WINDFIELDS BELOW 700 MB WELL ENOUGH TO ALLOW THE
STRONGEST WINDS TO MIX DOWN TO THE SURFACE. AS A RESULT, WINDS WILL
BE GUSTY STARTING SATURDAY AFTERNOON INTO SATURDAY NIGHT, BUT IN
MOST AREAS THE LACK OF WELL-ALIGNED WINDS WILL CUT DOWN ON THE
STRENGTH OF THEM AT THE SURFACE. THE MAIN EXCEPTION IS ALONG THE
CREST AND IN THE EASTERN SLOPES OF THE SOUTHERN SIERRA NEVADA, WHERE
MODEL CROSS SECTIONS FROM THE ARW AND NMM MODELS BOTH SHOW WINDS
REACHING 50 KTS AT LEAST DOWN TO MID-SLOPE SATURDAY EVENING.
ALTHOUGH THE JET IS STRONG, THE FLOW LACKS A CROSS BARRIER COMPONENT
AND AS A RESULT NO REAL CRITICAL LAYER DEVELOPS. THUS THE THREAT OF
STRONG DOWNSLOPE WINDS INTO THE OWENS VALLEY LOOKS LOW ENOUGH TO
KEEP THEM OUT OF ANY HEADLINES, THOUGH SOME LOCAL GUSTS COULD REACH
OR EXCEED 40 MPH NEAR CANYON OPENINGS. A WIND ADVISORY WAS ISSUED
FOR THE CREST AND EASTERN SLOPES OF THE SOUTHERN SIERRA NEVADA WHERE
SEVERAL HOURS OF WIND GUSTS OF 50-65 MPH SHOULD MATERIALIZE SATURDAY
AFTERNOON AND EVENING. ELSEWHERE GUSTS UP TO 40 MPH WILL BE POSSIBLE
SATURDAY AFTERNOON AND EVENING FROM THE SOUTHWEST. ALTHOUGH MOISTURE
LACKS, ENOUGH MOISTURE IN THE 700-500 MB LAYER (MID-LEVELS) IS SHOWN
TO JUSTIFY A FEW SHOWERS IN THE SOUTHERN SIERRA AND IN NORTHERN
LINCOLN COUNTY FROM SATURDAY MORNING INTO SATURDAY EVENING AHEAD OF
THE FRONT. SNOW LEVELS WILL MAINLY BE ABOVE 9500 FEET.

THE FRONT IS EXPECTED TO PRESS SOUTH ACROSS THE AREA SATURDAY NIGHT
AND GUSTY NORTHWEST TO NORTH WINDS ARE EXPECTED BEHIND IT SATURDAY
NIGHT INTO SUNDAY. THE NORTHWEST PART OF THE LAS VEGAS VALLEY SHOULD
SEE SOME GUSTS TO 35 MPH SATURDAY NIGHT INTO SUNDAY MORNING. WINDS
MAY GET CLOSE TO LAKE WIND ADVISORY CRITERIA SUNDAY MAINLY IN THE
LAUGHLIN-BULLHEAD CITY AREA. DRIER AIR WORKING IN SHOULD END ANY
PRECIPITATION AS WELL AS CLEAR OUT MOST OF THE CLOUDS FOR SUNDAY.

TEMPS SHOULD BE A FEW DEGREES WARMER TOMORROW AND SHOULD TAKE A RUN
AT 70 IN LAS VEGAS. HOWEVER, FORECAST SOUNDINGS SHOW SEVERAL DEGREES
OF COOLING FOR SUNDAY WHICH WILL DROP HIGHS BACK CLOSER TO NORMAL.

.LONG TERM...MONDAY THROUGH FRIDAY NIGHT.

NORTHWEST FLOW ALOFT LINGERS ACROSS THE AREA FROM MONDAY INTO
TUESDAY AS THE AREA SITS BETWEEN A RIDGE OFFSHORE AND A TROUGH OVER
THE INTERMOUNTAIN WEST. FORECAST SOUNDINGS SHOW AN INVERSION BOTH
DAYS BETWEEN 2200 AND 3000 FEET WHICH WILL KEEP THE VALLEYS FROM
WARMING BACK UP QUICKLY INITIALLY. THUS WE HAVE KEPT HIGHS COOLER
THAN WHAT FORECAST SOUNDINGS SUGGEST. BY WEDNESDAY A RIDGE OFFSHORE
IS SLATED TO SHIFT EAST INTO THE SOUTHWEST AND THEN MOVE EAST ON
THANKSGIVING DAY. THIS WILL HELP TO MIX THE LOW-LEVELS BETTER AND
THUS WARM UP TEMPS SEVERAL DEGREES IN THE LOWER/DEEPER VALLEY AREAS
ESPECIALLY BY THANKSGIVING DAY. ANOTHER MID/UPPER LEVEL TROUGH AXIS
IS SHOWN TO MOVE ACROSS THE AREA ON FRIDAY, HOWEVER, AT THIS TIME,
MOISTURE LACKS, THUS THE FORECAST REMAINS DRY. SOME INCREASE
IN CLOUDS AND WIND ARE LIKELY, HOWEVER, NO STRONG WINDS APPEAR TO BE
A THREAT AT THIS TIME.
&&

.AVIATION...FOR MCCARRAN...WINDS ARE EXPECTED TO REMAIN MAINLY UNDER
8 KTS FAVORING TYPICAL DIURNAL TRENDS THROUGH SATURDAY AFTERNOON.
SCT-BKN CLOUDS MAINLY AOA 10 KFT TONIGHT THROUGH SATURDAY MORNING
TRENDING TOWARD FEW-SCT BY SATURDAY AFTERNOON. A COLD FRONT WILL
PASS ACROSS THE LAS VEGAS VALLEY SATURDAY EVENING BETWEEN 06Z AND
10Z AND SHIFT WINDS FROM THE SOUTH TO NORTHWEST. GUSTS TO 25 KTS ARE
POSSIBLE AHEAD OF AND BEHIND THE COLD FRONT.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...SCT-BKN CLOUDS AOA 20K FEET TONIGHT THROUGH SATURDAY
MORNING NORTH OF A KIYK-KLAS-KSGU LINE TRENDING TOWARD FEW-SCT
SATURDAY AFTERNOON INTO SATURDAY NIGHT. MOUNTAIN OBSCURATIONS ARE
POSSIBLE IN THE OWENS VALLEY SATURDAY MORNING AND AFTERNOON. WINDS
WILL FAVOR TYPICAL DIURNAL PATTERNS THROUGH SATURDAY MORNING.
SATURDAY AFTERNOON INTO SATURDAY EVENING WINDS WILL INCREASE FROM
THE SOUTHWEST TO WEST AT 8-16 KTS WITH GUSTS OF 20-30 KTS. HIGHER
WINDS ARE EXPECTED IN THE MOUNTAINS OF INYO AND ESMERALDA COUNTIES
WHERE GUSTS OVER 45 KTS COULD OCCUR. A COLD FRONT WILL PRESS ACROSS
THE AREA SATURDAY NIGHT SHIFTING WINDS TO THE NORTHWEST TO NORTH.
WIND GUSTS OF 20-30 KTS CAN BE EXPECTED BEHIND THE FRONT ON SUNDAY
ESPECIALLY IN THE COLORADO RIVER VALLEY FROM KIFP ON SOUTH.
&&

.SPOTTER INFORMATION STATEMENT...SPOTTERS SHOULD REPORT ANY CRITERIA
ACCORDING TO STANDARD OPERATIONS PROCEDURES.
&&

$$

STACHELSKI

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