Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 261706 AAA
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
905 AM PST MON JAN 26 2015

.SYNOPSIS...INCREASING CLOUDS EXPECTED TODAY WITH RAIN MOVING INTO
PARTS OF NORTHWEST ARIZONA AND THE MOJAVE DESERT BY THE AFTERNOON.
RAIN CHANCES WILL EXPAND NORTHWARD TONIGHT AND LIFT INTO THE GREAT
BASIN TUESDAY. IMPROVING CONDITIONS ARE EXPECTED TUESDAY AFTERNOON
THROUGH WEDNESDAY BEFORE THE POSSIBILITY OF MORE UNSETTLED WEATHER
RETURNS LATE IN THE WEEK.
&&

.UPDATE...RADAR DETECTING NARROW LINE OF LIGHT RAIN RUNNING FROM
NEAR TWENTYNINE PALMS CA SOUTHEAST TOWARD YUMA AZ. BAND ASSOCIATED
WITH JETSTREAK ACROSS SOUTHERN CALIFORNIA THIS MORNING. SEE A REPORT
OF NEARLY TWO TENTH OF AN INCH FROM A STATION NORTH OF YUMA,
OTHERWISE RAIN AMOUNTS RANGE FROM A FEW HUNDREDTHS OF AN INCH DOWN
TO A TRACE. 12Z NAM/GFS PLUS THE 15Z HRRR SHIFT THIS BAND NORTHWEST
ACROSS WESTERN SAN BERNARDINO COUNTY THIS AFTERNOON WITH ADDITIONAL
BANDS DEVELOPING ACROSS EASTERN SAN BERNARDINO COUNTY AND SOUTHERN
MOHAVE COUNTY. UPDATED EARLIER TO INCREASE POPS FOR SOUTHERN SAN
BERNARDINO COUNTY AND THE AREA AROUND LAKE HAVASU CITY THIS
AFTERNOON.

A FEW 12Z MODELS NOW SUGGESTING RAIN BAND WILL BE MORE BROKEN AS IT
LIFTS NORTH INTO SOUTHERN NEVADA TONIGHT. THIS EVENT NOW LOOKING
MORE OF A HIGH POP, LOW QPF EVENT FOR THE LAS VEGAS VALLEY. WILL
ADDRESS AND POTENTIAL CHANGES IN THE AFTERNOON PACKAGE.
&&

.PREV DISCUSSION...326 AM PST MON JAN 26 2015

.SHORT TERM...THROUGH TUESDAY NIGHT.

FAIRLY EXTENSIVE CLOUD SHIELD WRAPPING AROUND THE BAJA LOW IS NOW
BEGINNING TO NUDGE INTO OUR SOUTHERN BORDER AND WILL CONTINUE TO
INVADE OUR SKIES THROUGH THE EARLY MORNING HOURS. FOR THE MOST PART
THE FORECAST REMAINS ON TRACK WITH SOME TENDENCY NOTED FOR THE
MODELS TO TAKE THE HEAVIEST QPF UP THROUGH SAN BERNARDINO COUNTY AND
INTO INYO COUNTY WITH LESSER AMOUNTS FURTHER EAST.  REGARDLESS...I
STILL ANTICIPATE A FAIRLY WIDESPREAD RAIN EVENT FOR OUR AREA.

AS FOR THE DETAILS...RAIN WILL BEGIN TO BREAK OUT ACROSS SOUTHERN
SAN BERNARDINO COUNTY BY LATE MORNING OR EARLY AFTERNOON. THE LATEST
HRRR GUIDANCE HAS SOME LIGHT PRECIPITATION BREAKING OUT ROUGHLY
SOUTH OF INTERSTATE 40 BY NOON. THIS PRECIP BAND WILL CONTINUE TO
EXPAND THROUGH THE AFTERNOON WHILE SLOWLY LIFTING NORTHWARD. BY
NIGHTFALL THE PRECIP BAND WILL CONTINUE TO WORK NORTHWARD INTO INYO
COUNTY AS WELL ACROSS CLARK AND MOHAVE COUNTIES BEFORE LIFTING INTO
OUR SOUTHERN GREAT BASIN ZONES EARLY TUESDAY MORNING.

AS MENTIONED PREVIOUSLY...MODELS HAVE TRENDED TOWARDS TAKING THE
BEST QPF INTO INYO COUNTY WITH LESSER AMOUNTS FURTHER EAST. IN
FACT...IT LOOKS LIKE MUCH OF INYO COUNTY OUTSIDE OF THE LOWEST
VALLEYS STAND A GOOD CHANCE TO PICK UP A QUARTER TO A HALF AN INCH
OF PRECIPITATION...AND EVEN MORE ALONG THE SIERRA CREST. FURTHER
EAST ACROSS CLARK AND MOHAVE COUNTY...I STILL ANTICIPATE WIDESPREAD
RAIN BUT AMOUNTS MAY STRUGGLE TO EXCEED A TENTH OF AN INCH IN THE
LOWEST DESERT VALLEYS.  HOWEVER...PLAYING DEVILS ADVOCATE...WITH
SUCH A MOISTURE RICH AIRMASS MOVING IN...IT WONT TAKE MUCH TO
SQUEEZE OUT MORE PRECIP THAN INDICATED BY MODEL GUIDANCE.  WITH ALL
THIS IN MIND...IVE STAYED  THE COURSE WITH THE FORECAST AND
MAINTAINED SIMILAR QPF VALUES ACROSS THE LAS VEGAS METRO AS WHAT WAS
INHERITED...WITH VALUES BETWEEN A TENTH AND A QUARTER OF AN INCH
EXPECTED.

FINALLY...SNOW LEVELS WILL BE RATHER HIGH FOR LATE JANUARY WITH THIS
STORM THANKS TO THE SUBTROPICAL ORIGIN OF THE MOISTURE. SEVERAL
INCHES OF SNOW ARE POSSIBLE ABOVE 7500 FEET PARTICULARLY ACROSS THE
SIERRA AND AND ALSO THE HIGHEST REACHES OF THE SPRING MOUNTAINS.
AFTER COORDINATING WITH THE NEIGHBORING OFFICES...DECIDED TO HOLD
OFF ON ANY WINTER WEATHER HEADLINES FOR NOW. THE DAY SHIFT CAN
REEVALUATE THE NEED FOR ANY ADVISORIES. ANY SNOW OF CONSEQUENCE WITH
REGARDS TO IMPACTS WOULD BE AT ELEVATIONS ABOVE 8000 FEET SUCH AS
THOSE LEADING TO LEE CANYON OR OVER THE SIERRA CREST.


.LONG TERM...WEDNESDAY THROUGH SUNDAY.

THE NEXT UPPER LEVEL DISTURBANCE TO AFFECT THE AREA WILL SLIDE INTO
THE REGION ON THURSDAY AFTERNOON...REINTRODUCING PRECIPITATION
CHANCES ACROSS MUCH OF THE AREA THROUGH SATURDAY. CURRENTLY THE
PRIMARY CONCERN WITH THIS NEXT IMPULSE IS THE TIMING DIFFERENCES
BETWEEN MODEL RUNS...WITH THE GFS BEING MUCH MORE PROGRESSIVE THAN
THE EUROPEAN AND NAM. HOWEVER LOOKING AT RUN TO RUN
CONSISTENCY...EACH MODEL HAS SHOWN SIGNS OF SPEEDING UP THIS NEXT
IMPULSE TO SOME DEGREE OVER THE PAST FEW MODEL RUNS. THIS TREND
WOULD SUPPORT LESS POPS WEST OF THE COLORADO RIVER AND WOULD FAVOR
FAR EASTERN NEVADA AND ARIZONA FOR THE HIGHEST POPS. DID SLIGHTLY
INCREASE POPS IN THESE AREAS FOR THESE REASONS AND THE FACT THAT
SUFFICIENT UPPER DIFLUENCE CONTINUES TO LOOK MOST LIKELY THERE.
MODELS CONTINUE TO SUPPORT THIS LOW WRAPPING UP AND MOVING SOUTHWARD
AS HIGH PRESSURE BUILDS BACK INTO THE AREA DURING THE LATTER PART OF
THE WEEKEND INTO EARLY NEXT WEEK. THIS WILL LEAD TO A DRYING TREND
ACROSS THE AREA LATE SATURDAY THROUGH THE BEGINNING OF THE WEEK. THE
WARM NATURE OF THIS SYSTEM WILL KEEP SNOW LEVELS HIGH FOR THIS TIME
OF YEAR...WITH LEVELS AT OR AROUND 7000 FEET THROUGH THIS EVENT.
TEMPERATURES WILL REMAIN A FEW DEGREES ABOVE NORMAL BEFORE A SLIGHT
WARMING TREND OCCURS LATE THIS WEEKEND INTO THE BEGINNING OF THE
WEEK.
&&

.AVIATION...FOR MCCARRAN...INCREASING CLOUDS EXPECTED TODAY WITH
RAIN EXPECTED TO IMPACT THE AIRFIELD TONIGHT AFTER 6Z. BIGGEST
CONCERNS WILL BE REDUCTIONS IN VISIBILITY AND LOW CIGS. CIGS FALLING
BELOW 5K EXPECTED AFTER 6Z AND POSSIBLY FALLING BELOW 3K AT TIMES
DURING THE HEAVIEST RAINFALL. WINDS THROUGH THE PERIOD LOOK TO
REMAIN LIGHT.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...INCREASING CLOUDS AND RAIN EXPECTED FOR MUCH OF THE
AREA STARTING THIS AFTERNOON ACROSS AREAS SOUTH OF A KDAG-KEED-KIGM
LINE AND LIFTING NORTH IN THE EVENING.  REDUCTIONS IN VISIBILITY AND
LOW CIGS EXPECTED IN THE HEAVIER RAINFALL WITH WIDESPREAD MOUNTAIN
OBSCURATIONS EXPECTED.

&&

.SPOTTER INFORMATION STATEMENT...SPOTTER ACTIVATION IS NOT EXPECTED
BUT SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT RAIN OR SNOW
IN THE COMING DAYS.

&&

$$

UPDATE...PIERCE
SHORT TERM/AVIATION...OUTLER
LONG TERM...PULLIN

FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:

HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER




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