Area Forecast Discussion
Issued by NWS Las Vegas, NV

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000
FXUS65 KVEF 300928
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
230 AM PDT SAT APR 30 2016

.SYNOPSIS...WIDESPREAD SHOWERS AND THUNDERSTORMS CAN BE EXPECTED
TODAY ESPECIALLY ACROSS SOUTHERN NEVADA AND NORTHWEST ARIZONA AS A
WEATHER SYSTEM MOVES THROUGH. GUSTY NORTH WINDS WILL ALSO PERSIST
ACROSS INYO COUNTY. SHOWER CHANCES STICK AROUND THROUGH THE WEEKEND
BEFORE THINGS BEGIN TO DRY OUT AND WARM UP NEXT WEEK. TEMPERATURES
WILL RETURN TO ABOVE NORMAL VALUES BY TUESDAY AND REMAIN THERE
THROUGH THURSDAY BEFORE ANOTHER WEATHER SYSTEM BRINGS INCREASING
CLOUDS AND COOLER TEMPERATURES TO THE REGION...ALONG WITH A CHANCE
OF SHOWERS LATE IN THE WEEK.

&&

.SHORT TERM...THROUGH SUNDAY NIGHT.

PRECIPITATION IS UNFOLDING AS ANTICIPATED THIS MORNING WITH
WIDESPREAD RAINFALL OBSERVED THROUGH 2 AM ACROSS THE SOUTHERN GREAT
BASIN SOUTHWARD TO THE NEVADA SECURITY SITE AND LIGHT RAIN HAS JUST
BEGUN TO FALL ACROSS THE CENTRAL LAS VEGAS VALLEY. AMOUNTS TO OUR
NORTH HAVE GENERALLY BEEN IN THE 0.10-0.25 RANGE.  HIGH RESOLUTION
MODELS CONTINUE TO FAVOR SOUTHERN NEVADA AND EASTERN INYO
COUNTY/NORTHEASTERN SAN BERNARDINO COUNTY FOR WIDESPREAD LIGHT TO
MODERATE PRECIPITATION THROUGH THE MORNING HOURS SUPPORTED BY
FAVORABLE JET DYNAMICS AND COOLING TEMPERATURES ALOFT AS THE CLOSED
LOW DROPS SOUTHWARD. SIMILAR PRECIPITATION AMOUNTS OF BETWEEN 0.10-
0.25" CAN BE EXPECTED ACROSS THE DESERT VALLEYS IN THESE
AREAS...WITH GREATER AMOUNTS IN THE HIGHER TERRAIN. LATEST CHECK OF
THE TEMPERATURE AT MT CHARLESTON IS 34F WITH SOME RAIN AND SNOW
MIXING IN...COOLING 700MB TEMPERATURES THROUGH MORNING WILL ENSURE
THAT THIS CHANGES OVER TO MOSTLY SNOW ABOVE THE 7000 FOOT LEVEL BY
SUNRISE WITH 1-2 INCHES POSSIBLE NEAR THE CITY OF MT CHARLESTON.
SEVERAL INCHES OF SNOW ARE LIKELY TO ACCUMULATE ABOVE 8500 FEET BY
MID MORNING.

ADDITIONAL SHOWERS AND THUNDERSTORMS WILL BREAK OUT LATER THIS
MORNING BENEATH THE CLOSED LOW THANKS TO THE COOL 500MB TEMPERATURES
ALOFT EXCEEDING -20C. A FEW STORMS MAY PRODUCE SMALL HAIL AND GUSTY
WINDS. STRONGEST THUNDERSTORMS ARE MOST FAVORED ACROSS THE EASTERN
MOJAVE DESERT AND MOHAVE COUNTY CLOSER TO THE COLDEST UPPER LEVEL
TEMPERATURES.

THE CLOSED LOW RESPONSIBLE FOR TODAYS RAINFALL AND THUNDERSTORMS
WILL PUSH EASTWARD SUNDAY BUT RESIDUAL MOISTURE AND INSTABILITY
BENEATH A BROAD TROUGH ACROSS THE WEST WILL FAVOR ADDITIONAL
SCATTERED SHOWER AND THUNDERSTORM ACTIVITY. TEMPERATURES SUNDAY
AFTERNOON WILL REBOUND CLOSER TO SEASONAL NORMALS...BUT STILL BE A
FEW DEGREES ON THE COOL SIDE.

.LONG TERM...THROUGH SATURDAY.

CONFIDENCE REMAINS MODERATE TO HIGH IN THE LONG TERM FORECAST, AS
MODELS ARE IN QUITE GOOD AGREEMENT. THERE ARE SOME TIMING
DIFFERENCES FOR THE LATTER HALF OF THE WEEK AND INTO NEXT WEEKEND,
BUT THE OVERALL SYNOPTIC PICTURE REMAINS THE SAME.

LINGERING MOISTURE AND AFTERNOON INSTABILITY ON MONDAY WILL CONTINUE
THE CHANCE OF SOME SHOWERS AND ISOLATED THUNDERSTORMS OVER SOUTHEAST
NEVADA AND NORTHWEST ARIZONA. RIDGING ALOFT WILL THEN MOVE OVER THE
REGION TUESDAY, WITH DRY AND WARMER CONDITIONS ANTICIPATED. THE
RIDGE AXIS WILL SLOWLY MOVE EAST WEDNESDAY AS A LARGE EASTERN
PACIFIC TROUGH APPROACHES THE WEST COAST. SOUTHERLY WINDS WILL
INCREASE, BECOMING BREEZY TO LOCALLY WINDY. THIS MIXING WILL HELP
TEMPERATURES CLIMB WELL ABOVE NORMAL WEDNESDAY INTO THURSDAY. THE
TROUGH WILL THEN SPIN INTO A CLOSED, CUTOFF LOW ON THURSDAY AND
GRADUALLY SLIDE EAST ACROSS THE DESERT SOUTHWEST FRIDAY THROUGH THE
WEEKEND. MOISTURE WILL SPREAD FROM WEST TO EAST ACROSS OUR AREA
THURSDAY AND FRIDAY. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE OVER
NORTHERN INYO COUNTY THURSDAY BEFORE PRECIP CHANCES SPREAD EAST TO
MOST LOCATIONS BY FRIDAY. THE CENTER OF THE UPPER LOW WILL BE
PUSHING INTO NORTHERN ARIZONA ON SATURDAY, YET WE COULD STILL SEE
SHOWERS ACROSS MOST OF THE AREA AS ANOTHER PV ANOMALY RIDES DOWN THE
BACK SIDE OF THE UPPER LOW SATURDAY INTO SUNDAY. TEMPERATURES WILL
TREND COOLER STARTING THURSDAY, WITH BELOW NORMAL TEMPERATURES
EXPECTED OVER THE WEEKEND.


&&

.AVIATION...FOR MCCARRAN...TRICKY FORECAST TODAY WITH PRECIP, CIGS,
AND WINDS ALL CONCERNS. RAIN SHOWERS ARE SPREADING INTO THE VALLEY
AT THIS TIME WITH A NOTICEABLE SHIFT IN WINDS TO A MORE NNW
DIRECTION WITH A BRIEF GUSTY PERIOD (20-35 KTS) AS THE OUTFLOW
BOUNDARY MOVES THROUGH. MOST GUIDANCE SUGGESTS SHOWERS WILL CONTINUE
THROUGH AT LEAST EARLY AFTERNOON BECOMING SPOTTIER AFTER 21Z. CIGS
EXPECTED TO LOWER INTO THE 4-10 KFT RANGE THROUGH 00Z BEFORE SLOWLY
LIFTING THEREAFTER. LOWEST CIGS EXPECTED IN THE MORNING OR DURING
HEAVY SHOWERS. HI-RES MODELS SUGGEST WINDS WILL VARY BETWEEN 330 AND
060 THROUGH THIS EVENING WITH PERHAPS SOME FAVORING OF THE NORTHWEST
WINDS THIS MORNING AND THE NORTHEAST WINDS THIS AFTERNOON.
SPEEDS SHOULD GENERALLY AVERAGE AROUND 10 KTS. HOWEVER...AS USUAL
WITH SHOWERS...EXPECT FAIRLY ERRATIC SPEEDS/DIRECTIONS. SMALL CHANCE
OF AN ISOLATED LIGHTNING STRIKE BUT CONFIDENCE TOO LOW TO INCLUDE IN
THE TAF AT THIS TIME. CONDITIONS ARE FAVORABLE FOR ICING TODAY
(AROUND 10 KFT)...AND LOCALIZED TURBULENCE IS LIKELY IN VICINITY OF
SHOWERS. MOUNTAIN OBSCURATIONS ARE PROBABLE THROUGH THIS EVENING.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...AS A POTENT STORM SYSTEM MOVES THROUGH THE REGION
TODAY...PRECIP IS DEVELOPING AND SPREADING SOUTHWARD/EASTWARD ACROSS
THE AREA AT THIS TIME. CIGS WILL LOWER TO 4-10 KFT IN VICINITY OF
SHOWERS AND POSSIBLY EVEN LOWER IN THE HEAVIEST PRECIP. ISOLATED
LIGHTNING STRIKES ARE POSSIBLE ACROSS THE AREA THROUGH EARLY
EVENING. WINDS ARE EXPECTED TO TRANSITION TO NORTHERLY BY MID-
MORNING ACROSS ALL AREAS EXCEPT THE MOJAVE DESERT, WHICH MAY KEEP A
MORE WESTERLY COMPONENT THROUGH THE DAY. SPEEDS/GUSTS SHOULD BE
STRONGEST IN INYO, ESMERALDA, NYE, AND WESTERN SAN BERNARDINO
COUNTIES (20-30 KTS WITH GUSTS UP TO 40 KTS). CIGS SHOULD GRADUALLY
BEGIN TO LIFT BY THIS EVENING AS PRECIP SLOWLY BEGINS TO WIND DOWN
FROM NORTHWEST TO SOUTHEAST. CONDITIONS ARE FAVORABLE FOR ICING
(AROUND 10 KFT) ACROSS THE REGION TODAY. LOCALIZED TURBULENCE IS
LIKELY WITH ASSOCIATED SHRA/TSRA...AND MOUNTAIN OBSCURATIONS ARE
LIKELY THROUGH THIS EVENING.

&&

.SPOTTER INFORMATION STATEMENT...ACTIVE WEATHER IS EXPECTED OVER
THE WEEKEND.  SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT
WEATHER ACCORDING TO STANDARD OPERATING PROCEDURES.
&&

$$

SHORT TERM...OUTLER
AVIATION...SHAFFER
LONG TERM...PADDOCK

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