Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 021718 AAA
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
918 AM PST MON MAR 2 2015

.SYNOPSIS...STEADY PRECIPITATION ACROSS CLARK, LINCOLN AND MOHAVE
COUNTIES WILL TAPER TO SHOWERS BY THIS AFTERNOON. OTHERWISE ISOLATED
TO SCATTERED SHOWERS ARE POSSIBLE THROUGH THIS AFTERNOON OVER THE
REMAINDER OF THE AREA. SNOW LEVELS WILL MAINLY BE AROUND 5000 FEET.
ALTHOUGH A CHANCE FOR SHOWERS WILL LINGER TONIGHT THROUGH TUESDAY
EVENING ACROSS THE EASTERN HALF OF THE AREA, DRIER AIR WILL WORK
INTO THE WESTERN HALF ENDING THE CHANCE OF SHOWERS THERE. LOCALLY
GUSTY NORTH WINDS ARE EXPECTED WEDNESDAY MAINLY IN THE COLORADO
RIVER VALLEY. OTHERWISE EXPECT DRIER AND MILDER WEATHER FOR THE END
OF THE WEEK AND NEXT WEEKEND.
&&

.UPDATE...UPPER LOW EVIDENT ON SATELLITE OVER SO CAL THIS MORNING.
IMPRESSIVE MOISTURE FEED CONTINUING UP THROUGH MOHAVE COUNTY AND THE
EASTERN PORTIONS OF CLARK AND LINCOLN COUNTIES. ISSUED A WINTER
WEATHER ADVISORY FOR MOHAVE COUNTY FOR ELEVATIONS ABOVE 5000 FEET
BASED ON WEB CAM IMAGES OF THE HUALAPAI MTNS AND I-40 AT FORT ROCK.
WEST OF THE MOISTURE PLUME, LOW CLOUDS COVER MUCH OF THE SOUTHERN
GREAT BASIN AREA INTO INYO COUNTY. CLOUDS WERE MORE SCATTERED ACROSS
THE WESTERN MOJAVE DESERT. AS THE LOW AND ITS ASSOCIATED COLD POOL
LIFTS TO THE NORTHEAST TODAY, CONVECTIVE SHOWER AND ISOLATED
THUNDERSTORM ACTIVITY IS EXPECTED OVER MUCH OF THE EASTERN CWA.
ACROSS THE WESTERN AREAS, MORE ISOLATED TO SCATTERED SHOWERS ARE
FORECAST. FORECAST UPDATES ARE OUT. -SALMEN-
&&

.PREVIOUS DISCUSSION...347 AM PST...

.SHORT TERM...TODAY THROUGH TUESDAY.

A WELL DEFINED SWIRL CAN BE SEEN ON WATER VALOR IMAGERY THIS MORNING
SOUTH-SOUTHWEST OF POINT CONCEPTION SHOWING WHERE THE MID/UPPER
LEVEL LOW IMPACTING OUR AREA IS PRESENTLY AT. THE MAIN MOISTURE
PLUME AHEAD OF THIS LOW WHICH WAS FED NORTHEAST BY THE JET IS
STARTING TO SHIFT EAST. FOR CLARK COUNTY, THE STEADIER PRECIPITATION
SHOULD START TO SHUT-OFF BY LATER THIS MORNING. FOR THE LAS VEGAS
VALLEY SPECIFICALLY, STEADIER RAIN WILL LIKELY BE DONE BY DAYBREAK
OR NOT TOO LONG THEREAFTER. HOWEVER, ROADS WILL BE SLICK FOR THE
MORNING COMMUTE SO DRIVE CAREFULLY. STEADIER PRECIPITATION WILL
LINGER LONGER IN LINCOLN AND MOHAVE COUNTIES WHICH WILL TAKE UNTIL
VERY LATE THIS MORNING AND EARLY THIS AFTERNOON TO SEE AN END.

SNOW LEVELS WERE AROUND 4500-5000 FEET THIS MORNING ON AVERAGE.
LINCOLN COUNTY COULD SEE ANOTHER 1 TO 3 INCHES OF SNOW FROM THE
STEADIER PRECIPITATION TODAY AND THIS WILL JUSTIFY KEEPING THE
WINTER WEATHER ADVISORY GOING. ACROSS THE SPRING MOUNTAINS AND SHEEP
RANGE, THE BULK OF THE STEADIER SNOW IS DONE, HOWEVER, ADDITIONAL
SHOWERS THIS AFTERNOON ARE STILL POSSIBLE AND COULD DROP A FEW MORE
INCHES SO WILL KEEP THE ADVISORY GOING OUT OF CONCERN OF SLICK ROADS
FROM OLD SNOW AND ANY NEW SNOW.

THE MID/UPPER LEVEL LOW IS FORECAST TO EJECT NORTHEAST TODAY TOWARD
SOUTHERN NEVADA AND TRANSITION TO AN OPEN WAVE. ALTHOUGH THE AREA
WILL BE IN THE EXIT REGION OF THE THE JET, A NICE PV MAX CROSSES THE
AREA LATE THIS MORNING AND EARLY THIS AFTERNOON. THE LIFT FROM THIS
FEATURE AND LINGERING LOW AND MID-LEVEL MOISTURE SHOULD SET OFF SOME
SHOWERS ESPECIALLY ACROSS THE NORTHERN TWO-THIRDS OF THE AREA. IN
ADDITION, ENOUGH CAPE AND INSTABILITY AREN NOTED NORTHEAST OF THIS
FEATURE ACROSS LINCOLN, NORTHERN CLARK AND NORTHERN MOHAVE COUNTY
THAT ISOLATED THUNDERSTORMS CANNOT BE RULED OUT. LOW FREEZING LEVELS
WILL MAKE SMALL HAIL OR GRAUPEL POSSIBLE IN ANY STRONGER
THUNDERSTORMS.

ACROSS THE SOUTHERN THIRD OF THE AREA, DRIER AIR IS EXPECTED TO MOVE
IN LATER THIS MORNING INTO THIS AFTERNOON WHICH SHOULD AID IN
INCREASING WINDS FROM THE SOUTHWEST. GUSTS OF 25 TO 35 MPH ARE
POSSIBLE ACROSS THE SAN BERNARDINO COUNTY DESERTS, CLARK AND MOHAVE
COUNTIES THROUGH EARLY THIS EVENING. THIS MAY HELP TO SCOUR OUT SOME
OF THE LOW-LEVEL MOISTURE AND RAISE CLOUD BASES.

MODELS DO NOT SHOW THE LOW-LEVEL MOISTURE GOING AWAY FOR TONIGHT
ENTIRELY. SO, WHILE CONFIDENCE IS LOW WE WILL NEED TO WATCH OUT FOR
FOG. MOST AREAS SHOULD SEE SHOWERS END THIS EVENING, ESPECIALLY IN
THE WEST WHERE DRIER AIR WORKS IN.

TEMPS TODAY ARE TRICKY AS THE COLDER WRF AND ECMWF SOUNDINGS
STRUGGLE TO BRING LAS VEGAS ABOVE 50 FOR A HIGH. I WENT WITH A BLEND
OF THE LOWER END STAT GUIDANCE FOR HIGHS TODAY AS I THINK THOSE
COLDER SOUNDINGS ARE TOO LOW.

ON THE HEELS OF THIS FIRST SYSTEM ANOTHER MID/UPPER LEVEL LOW NEAR
THE REDWOOD COAST OF NORCAL WILL DROP SOUTH TODAY AND DROP DOWN THE
COAST TONIGHT INTO TOMORROW. THIS WILL PULL A POSITIVELY TILTED
MID/UPPER LEVEL TROUGH AXIS THROUGH OUR AREA ON TUESDAY FINALLY
SWEEPING EVERYTHING ON OUT. AS THE TROUGH AXIS PASS THROUGH LATE
TUESDAY MORNING INTO TUESDAY AFTERNOON WE CANNOT RULE OUT A FEW
SHOWERS MAINLY ACROSS LINCOLN, MOHAVE AND CLARK COUNTIES. GUSTY
NORTHWEST WINDS ARE EXPECTED BEHIND THE TROUGH AXIS. HIGHS TOMORROW
SHOULD BE SEVERAL DEGREES ABOVE TODAY BUT STILL ABOUT 6-8 DEGREES
BELOW NORMAL.

.LONG TERM...TUESDAY NIGHT THROUGH SUNDAY.

THE MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT WITH A DRY AND WARMING
PATTERN DOMINATED BY A BUILDING RIDGE OVER THE WESTERN STATES THE
LATTER PART OF THE WEEK INTO THE WEEKEND. NORTH WINDS AND
TEMPERATURES SEVERAL DEGREES BELOW NORMAL CAN BE EXPECTED TUESDAY
NIGHT AND WEDNESDAY WITH THE EXITING LOW PRESSURE SYSTEM FORECAST TO
BE OVER NORTHERN BAJA AND QUICKLY PULLING TO THE EAST. A DISTURBANCE
SLIDING DOWN THE LEADING EDGE OF THE RIDGE IS FORECAST TO BRUSH
SOUTHERN NEVADA AND NORTHWEST ARIZONA EARLY THURSDAY WHICH MAY
ENHANCE NORTH BREEZES SOMEWHAT. THEN THE WARMING TREND WILL KICK IN
THURSDAY THROUGH SUNDAY WITH THE GFS/GEM MODELS DEPICTING A STRONG
HIGH OVER THE GREAT BASIN. THE ECMWF IS LESS AMPLIFIED WITH THE
RIDGE BUT STILL KEEPS A DRY NORTHWEST FLOW OVER THE FORECAST
AREA WITH A RIDGE AXIS HOLDING ALONG THE WEST COAST. HIGH TEMPS
SHOULD CLIMB BACK INTO THE 70S FOR MUCH OF THE MOJAVE DESERT REGION
FOR THE WEEKEND.
&&

.AVIATION...FOR MCCARRAN...MOST OF THE STEADY LIGHT RAIN SHOULD BE
DONE WITH BY LATER THIS MORNING. WHILE A STRAY SHRA CANNOT BE RULED
OUT THROUGH THIS AFTERNOON AT THE AIRPORT COMPLEX, CONFIDENCE IS NOT
HIGH ENOUGH TO INCLUDE THIS IN THE TAF AND THUS THE TAF WILL BE KEPT
DRY AT THIS TIME. WINDS THIS MORNING WILL MAINLY BE 6 KTS OR LESS
AND TREND TOWARD TYPICAL DIURNAL DIRECTIONS. THE MAIN ISSUE TODAY
WILL BE HOW LONG CIGS REMAIN DOWN. DRIER AIR SHOULD START TO WORK IN
AROUND 21Z TODAY RESULTING IN GUSTIER SOUTHWEST WINDS WITH GUSTS TO
25 KTS. THIS SHOULD HELP BASES TO RISE ABOVE 5K FEET BUT BASES WILL
PROBABLY NOT GET MUCH HIGHER THAN 7K-9K FEET. THERE IS SOME
POTENTIAL TONIGHT THAT THE CLOUD DECK COULD FILL IN A BIT MORE IF
THE LOWER-LEVEL MOISTURE IS NOT SCOURED OUT OF THE LAS VEGAS VALLEY.
HOWEVER, CONFIDENCE IN THIS IS LOW-MODERATE AT BEST AT THIS TIME.
EITHER WAY SOME MOUNTAIN OBSCURATIONS WILL CONTINUE INTO TONIGHT.
WINDS SHOULD DECREASE AROUND 02Z TUESDAY TO 6-10 KTS FROM THE
SOUTH-SOUTHWEST.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...STEADIER PRECIPITATION SHOULD END ACROSS CLARK COUNTY
BY 18Z TODAY AND ACROSS MOHAVE AND LINCOLN COUNTIES BETWEEN 18Z AND
22Z. SNOW LEVELS ACROSS THE AREA WILL MAINLY BE 5K-6K FEET. MOST
AREAS OTHERWISE WILL SEE A FEW SHOWERS AROUND ESPECIALLY NORTH OF
KIYK-KLAS-KIGM LINE. WINDS WILL START TO PICK UP FROM THE SOUTHWEST
AROUND 21Z TODAY AND LAST THROUGH 02Z TUESDAY FROM KDAG-KLAS-KIGM
AND POINTS SOUTH WITH GUSTS OF 20-30 KTS EXPECTED. CIGS WILL MAINLY
BE 3K-6K FEET THIS MORNING THEN RISE TO 5K-9K FEET BY THIS AFTERNOON
WHERE PRECIPITATION ENDS. CIGS COULD POTENTIALLY LOWER ANOTHER 1K-2K
FEET TONIGHT ESPECIALLY WHERE THE LOW-LEVEL MOISTURE IS SLOW TO
LEAVE. ANY AREAS THAT CLEAR OUT ENOUGH COULD ALSO SEE PATCHY FG/BR
DEVELOP LATE TONIGHT. MOUNTAIN OBSCURATIONS ARE EXPECTED THROUGH
TONIGHT ESPECIALLY NEAR TALLER RANGES.
&&

.SPOTTER INFORMATION STATEMENT...SPOTTERS ARE REQUESTED TO REPORT
ANY SIGNIFICANT WEATHER ACCORDING TO STANDARD OPERATING PROCEDURES
TODAY THROUGH WEDNESDAY.
&&

$$

SHORT TERM/AVIATION...STACHELSKI
LONG TERM...ADAIR

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