Flash Flooding and Hail in Nevada, October 4 to 5, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
900 AM PDT SUN OCT 4 2015

.SYNOPSIS...A STRONG AND COOL EARLY SEASON STORM SYSTEM WILL BRING
WIDESPREAD SHOWERS AND THUNDERSTORMS TO THE REGION TODAY THROUGH
TUESDAY AS WELL AS ACCUMULATING HIGH MOUNTAIN SNOWFALL. SOME
THUNDERSTORMS COULD BE SEVERE THIS AFTERNOON AND MONDAY. AS THE
STORM SYSTEM DEPARTS TO THE EAST ON TUESDAY...LINGERING SHOWERS WILL
SLOWLY DIMINISH WITH DRY WEATHER RETURNING FOR THE SECOND HALF OF
THE WEEK. COOL TEMPERATURES EARLY IN THE WEEK WILL REBOUND TO NEAR
NORMAL THURSDAY ONWARD.
&&

.UPDATE...FORECAST IS PRETTY WELL ON TRACK THIS MORNING WITH ONLY A
FEW MINOR ADJUSTMENTS MADE. MOST OF THE ACTIVITY SO FAR THIS MORNING
HAS BEEN LIMITED TO CENTRAL NYE AND ESMERALDA COUNTY WHERE STRONG
FORCING AHEAD OF A CLOSED LOW NOW CENTERED OVER SOUTHERN CALIFORNIA
WAS AIDING IN A ORGANIZING BAND OF MORNING THUNDERSTORMS. WITHIN THE
PAST 30 MINUTES...ADDITIONAL STORMS HAVE FLARED UP OVER THE MOJAVE
PRESERVE AND WILL LIFT NORTHWARD WHILE EXPANDING IN COVERAGE THROUGH
THE MORNING HOURS...EVENTUALLY WORKING INTO SOUTHERN NEVADA AND THE
SPRING MOUNTAINS...ESPECIALLY WEST OF LAS VEGAS.

WILL NEED TO CLOSELY MONITOR THIS RECENT DEVELOPMENT OF STORMS OVER
THE MOJAVE PRESERVE AS IT DEVELOPS NORTHWARD. IT IS LOCATED WITHIN A
REGION OF OVER 50KTS OF DEEP LAYER SHEAR WHICH WILL BE MORE THAN
SUFFICIENT TO SUPPORT ISOLATED SEVERE STORMS. ISOLATED HAIL WILL BE
THE PRIMARY THREAT.

-OUTLER-

.SHORT TERM...THROUGH TUESDAY NIGHT.

THE UPPER LOW THAT WILL BRING SIGNIFICANT IMPACTS TO OUR WEATHER
OVER THE NEXT FEW DAYS IS CURRENTLY OVER CENTRAL CALIFORNIA. SO FAR
MOST OF THE ACTIVITY HAS REMAINED NORTH AND WEST OF THE CWA...BUT
THERE HAVE ALSO BEEN A FEW LIGHTNING STRIKES OVER NORTHERN ESMERALDA
COUNTY SINCE MIDNIGHT AND RADAR IS PICKING UP A FEW LIGHT SHOWERS
OVER NORTHERN LINCOLN COUNTY. THE REMAINDER OF THE AREA HAS SEEN AN
INCREASE IN MID LEVEL CLOUDS EARLY THIS MORNING AND THE TREND OVER
THE NEXT FEW HOURS WILL BE FOR THOSE TO INCREASE AND LOWER. THE
CENTER OF THE LOW WILL CONTINUE TO TRACK SOUTH THIS MORNING AND
EVENTUALLY BE CENTERED JUST NORTH OF LOS ANGELES BY THIS AFTERNOON.
PRECIPITATION IS EXPECTED TO INCREASE THIS MORNING OVER MAINLY
ESMERALDA...INYO...AND CENTRAL NYE COUNTIES WITH MAINLY JUST SOME
ISOLATED SHOWERS ELSEWHERE. THE MAIN CONCERN FOR TODAY IS HOW FAST
THE PRECIPITATION DEVELOPS ACROSS SAN BERNARDINO...CLARK...MOHAVE
AND LINCOLN COUNTIES. THE 00Z/06Z NAM KEEPS MAINLY JUST SOME LIGHT
SHOWERS OVER THOSE AREAS MAINLY NORTH OF LAS VEGAS THROUGH MUCH OF
TODAY AS A DRY SLOT DEVELOPS. EVEN THE 00Z ECMWF SHOWS THOSE AREAS
TO REMAIN DRY THROUGH MUCH OF THE DAY. THE GFS IS THE ONLY MODEL
THAT STARTS TO BRING IN MORE WIDESPREAD PRECIPITATION TO MUCH OF THE
AREA DURING THE AFTERNOON. EVEN THOUGH THE MODELS REALLY DONT SHOW
MUCH QPF FOR THE EASTERN HALF OF THE CWA I STILL THINK THAT THERE
WILL BE ENOUGH ENERGY AND INSTABILITY TO GENERATE SOME AFTERNOON
THUNDERSTORMS. I DID LOWER POPS FOR THE EASTERN HALF OF THE CWA THIS
MORNING...BUT DID KEEP THE CURRENT POPS ALONE FOR THE AFTERNOON.
SOUTH TO SOUTHEAST WINDS WILL ALSO INCREASE THIS MORNING WITH BREEZY
TO WINDY CONDITIONS OVER THE EASTERN HALF OF THE AREA...BUT ARE
EXPECTED TO REMAIN BELOW ADVISORY LEVELS. AS FOR SNOWFALL...THINK
THAT THE SIERRA LOOKS GOOD FOR ACCUMULATING SNOW TODAY...BUT WITH
WARM AIR ADVECTING AHEAD OF THE LOW...THE SPRING MOUNTAINS AND SHEEP
RANGE MOST LIKELY WILL NOT SEE SIGNIFICANT SNOW UNTIL LATE TONIGHT
AND MONDAY. THE 6-12 INCHES ABOVE 8500 FEET IS STILL POSSIBLE FOR
THOSE LOCATIONS AND WILL NOT CHANGE THE CURRENT ADVISORY. AS THE LOW
STARTS TO TURN MORE EASTERLY TONIGHT WE WILL START TO SEE MORE
WIDESPREAD MODERATE RAINFALL OVER MUCH OF THE CWA...ESPECIALLY
INYO...SOUTHERN NEVADA AND NORTHWEST ARIZONA WHICH WILL LAST THROUGH
MUCH OF MONDAY. THUNDERSTORMS WILL ALSO REMAIN A POSSIBILITY TONIGHT
THROUGH MONDAY WITH SOME STORMS POSSIBLE SEVERE AS SHEAR AND
INSTABILITY REMAIN HIGH. THINGS WILL START TO TAPER OFF FROM WEST TO
EAST MONDAY NIGHT AND TUESDAY WITH ONLY THE FAR EASTERN AREAS OF THE
CWA SEEING PRECIPITATION CHANCES BY TUESDAY AFTERNOON.

.LONG TERM...WEDNESDAY THROUGH SATURDAY.

THE UPPER LEVEL LOW THAT WILL KEEP THE SHORT TERM PERIOD ACTIVE WILL
BE PUSHING SOUTHEAST THROUGH AZ WEDNESDAY BEFORE STALLING OVER
NORTHERN MEXICO/WESTERN TX THURSDAY NIGHT. IN IT'S WAKE A STRONG
RIDGE OF HIGH PRESSURE IS FORECAST TO DEVELOP...BRINGING
DRIER...WARMER...AND CALMER CONDITIONS TO THE REGION. THIS RIDGE IS
EXPECTED TO DOMINATE WELL INTO THE WEEKEND WITH TEMPERATURES RISING
BACK ABOVE NORMAL. WE'LL BE KEEPING AN EYE ON THE UPPER LEVEL LOW AS
MODELS CONTINUE TO HINT THAT AT LEAST SOME OF THE ENERGY MAY
RETROGRADE BACK WEST TOWARDS THE REGION SATURDAY AND SUNDAY...AND
COULD IMPACT THE REGION (AGAIN) BY EARLY NEXT WEEK.
&&

AVIATION...FOR MCCARRAN...LIGHT WINDS THIS MORNING WILL TRANSITION
TO A MORE SOUTHEAST DIRECTION AFTER 15Z WITH SPEEDS INCREASING TO
AROUND 8-12 KTS AND GUSTS UP TO 20 KTS. CLOUDS WILL CONTINUE TO
DEVELOP AND LOWER THROUGH THE MORNING WITH SCT-BKN110 BECOMING
BKN080-100 BY LATE MORNING. CLOUDS WILL CONTINUE TO LOWER DURING THE
AFTERNOON TO AROUND 5-7K FEET AND PRECIPITATION CHANCES WILL ALSO
INCREASE. THE CHANCE FOR SHRA/TSRA WILL ALSO EXIST IN ALL OF THE
APPROACH CORRIDORS THIS AFTERNOON. IT DOES NOT LOOK LIKE THE
HEAVIEST AND MORE WIDESPREAD PRECIPITATION WILL OCCUR UNTIL LATE
AFTERNOON AND OVERNIGHT...BUT CIGS DOWN TO 3-5K FEET AND VSBYS DOWN
TO 4-5SM WILL BE POSSIBLE OVERNIGHT AND ESPECIALLY MONDAY.
MECHANICAL TURBULENCE DUE TO A CHANGE IN WIND DIRECTION AND SPEED
WITH HEIGHT.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...CLOUDS WILL LOWER THROUGH THE DAY AND PRECIPITATION
WILL BECOME MORE WIDESPREAD. FOR THIS MORNING IT LOOKS LIKE THE MORE
CONCENTRATED AREA OF PRECIPITATION WILL OCCUR OVER ESMERALDA AND
CENTRAL NYE COUNTIES AND EVENTUALLY INCLUDE INYO BY THIS AFTERNOON.
THERE WILL BE ISOLATED THUNDERSTORMS THROUGH THE DAY AND SOME OF
THESE STORMS COULD BE SEVERE. THE MORE WIDESPREAD PRECIPITATION WILL
DEVELOP LATE THIS AFTERNOON AND EVENING OVER MOST AREAS WITH CIGS
DOWN TO 3-5K FEET AND VSBYS POSSIBLY AS LOW AS 3SM. MOUNTAIN
OBSCURATIONS ARE LIKELY ALONG WITH MECHANICAL TURBULENCE DUE TO A
CHANGE IN WIND DIRECTION AND SPEED WITH HEIGHT. REDUCED CIGS AND
VSBY AS WELL AS THE POTENTIAL FOR SHRA WILL LINGER INTO MONDAY AND
TUESDAY.

&&

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

SHORT TERM/AVIATION...GORELOW
LONG TERM...WOLCOTT

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