Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 230405 AAA
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
905 PM PDT FRI MAY 22 2015

.SYNOPSIS...A LOW PRESSURE SYSTEM WILL KEEP SHOWERS AND
THUNDERSTORMS GOING ACROSS THE REGION INTO THIS EVENING. SHOWERS AND
STORMS SHOULD BE MUCH LESS NUMEROUS SATURDAY FOLLOWED BY A SLIGHT
INCREASE IN ACTIVITY SUNDAY. A SLOW WARMING TREND WILL BEGIN
SATURDAY AND LAST INTO THE MIDDLE OF NEXT WEEK.
&&

.UPDATE...THE UPPER LOW CONTINUES TO LIFT OFF TO THE NORTHEAST AND
APPEARS TO BE CENTERED OVER NORTHWEST ARIZONA...JUST EAST OF
NORTHERN MOHAVE COUNTY. IR SATELLITE IMAGERY SHOWS ABUNDANT MOISTURE
WRAPPING INTO THE AREA ON THE BACKSIDE OF THE LOW WITH EMBEDDED
DISTURBANCES BRINGING MORE CLOUDS IN FROM THE NORTH. SHOWER ACTIVITY
HAS DEFINITELY BEEN ON THE DECREASE THIS EVENING WITH JUST A FEW
SHOWERS REMAINING ON RADAR OVER THE SIERRA AND MOHAVE COUNTY. THE
LIGHTNING DETECTION NETWORK LAST REPORTED LIGHTNING WITHIN THE CWA
AROUND 2 HRS AGO OVER EAST CENTRAL NYE COUNTY BUT THE CELL HAS SINCE
WEAKENED AND MOVED SOUTH. DECIDED TO PULL ANY MENTION OF THUNDER OUT
OF THE FORECAST FOR TONIGHT ALTHOUGH AN ISOLATED CELL IS NOT OUT OF
THE QUESTION AS SHOWERS MOVE IN FROM THE NORTH. THE UPDATE IS OUT.
&&

.AVIATION...FOR MCCARRAN...WINDS HAVE RETURNED TO A TYPICAL DIURNAL
DIRECTION AND ARE EXPECTED TO REMAIN SOUTH/SOUTHWEST THROUGH THE
NIGHT. FOR SATURDAY...EXPECT LIGHT SOUTHEAST WINDS THROUGH THE MID-
LATE MORNING TURNING TO THE SOUTHWEST AND INCREASING DURING THE
AFTERNOON UNDER VFR CONDITIONS.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...ISOLATED SHOWERS WILL CONTINUE THIS EVENING BEFORE
TAPERING OFF OVERNIGHT IN MOST AREAS. SHOWER AND THUNDERSTORM
ACTIVITY WILL BE FOCUSED MAINLY ACROSS THE NORTHERN AREAS ON
SATURDAY. THE STRONGER STORMS WILL FEATURE STRONG UPDRAFTS AND
CONVECTIVE TURBULENCE...AND BE CAPABLE OF PRODUCING GUSTY SURFACE
WINDS...AND SMALL HAIL. WEST TO NORTHWEST WINDS 10-15KTS ACROSS THE
SOUTHERN GREAT BASIN ON SATURDAY WITH 10-20KTS AND GUSTY ACROSS THE
MOJAVE DESERT.
&&

.PREVIOUS DISCUSSION...234 PM PDT...

.SHORT TERM...TODAY THROUGH SUNDAY.

THROUGH THIS EVENING...ACTIVE DAY WITH SHOWERS AND THUNDERSTORMS
(AND EARTHQUAKES) ACROSS THE REGION. THESE SHOWERS/THUNDERSTORMS
WERE ROTATING AROUND A LOW PRESSURE SYSTEM CURRENTLY CENTERED JUST
EAST OF NEEDLES. LATEST MESOANALYSIS INDICATED THE BEST INSTABILITY
WAS CENTERED AROUND AN AXIS EXTENDING FROM THE LOW CENTER NORTHEAST
TO TONOPAH. THE LOW WILL CONTINUE TO PUSH EAST INTO THE EVENING WITH
THIS AXIS OF INSTABILITY ROTATING SOUTHEAST BEHIND THE LOW.
MEANWHILE THE SHOWER/THUNDERSTORM ACTIVITY CURRENTLY OVER NORTHERN
MOHAVE COUNTY SHOULD WEAKEN TO MAINLY SHOWERS AS INSTABILITY
DECREASES THERE. AS A RESULT OF THIS PROGRESSION...CURRENT THINKING
IS THAT THE MAIN AREA OF CONCERN THROUGH THIS EVENING WILL BE ACROSS
CENTRAL/SOUTHERN INYO THROUGH SAN BERNARDINO INTO SOUTHERN MOHAVE
COUNTIES. RAINFALL AMOUNTS HAVE GENERALLY BEEN ONE TO TWO TENTHS OF
AN INCH WITH STORMS...AND THUS ONLY MINOR FLOODING IS A CONCERN.
COLD TEMPERATURES ALOFT WILL KEEP CHANCES FOR SMALL HAIL GOING.
SMALL DCAPE VALUES AND LIMITED SHEAR WILL KEEP THE WIND GUST
POTENTIAL LIMITED TO AROUND 35-45 MPH.

AS WE MOVE INTO SATURDAY THE LOW EXITS TO THE NORTHEAST AND CHANCES
FOR SHOWERS/THUNDERSTORMS BECOME LIMITED MAINLY TO AREAS NORTH OF
LAS VEGAS...WITH THE HIGHEST CHANCES OVER LINCOLN COUNTY WHERE
WRAP-AROUND MOISTURE WILL BE POISED TO MOVE OVER THE COUNTY. THIS
WILL BE SOMEWHAT OF A SHORT BREAK BETWEEN TODAY`S LOW AND A
SHORTWAVE THAT WILL MOVE THROUGH SUNDAY. AS A RESULT MORE ABUNDANT
SUNSHINE AND DECENT MIXING SHOULD ALLOW FOR TEMPERATURES TO CLIMB
SEVERAL DEGREES. A HIGH OF AROUND 80 IS EXPECTED IN LAS VEGAS.

THE AFOREMENTIONED SHORTWAVE WILL SLIDE ACROSS SOUTHERN CALIFORNIA
SUNDAY. THIS WILL BRING INCREASED CHANCES FOR SHOWERS/THUNDERSTORMS
ONCE AGAIN...MAINLY NORTH OF INTERSTATE 40. WENT AHEAD AND INCREASED
POPS OVER THE INHERITED GRIDS...AND INCLUDED A MENTIONED OF A SLIGHT
CHANCE FOR LAS VEGAS. THIS MAY NEED TO BE INCREASED FURTHER IF THE
CURRENT MODEL TRENDS CONTINUE.

.LONG TERM...MONDAY THROUGH FRIDAY.

AN UPPER LEVEL LOW OVER THE PACIFIC NORTHWEST WILL BE TRYING TO
COUNTER SOME WEAK SHORTWAVE RIDGING THAT IS ATTEMPTING TO SET UP OVER
THE DESERT SOUTHWEST ON MONDAY AFTERNOON. SOME LINGERING MOISTURE
AND INSTABILITY ACROSS LINCOLN COUNTY WILL BE ENOUGH TO CONTINUE TO
PROVIDE THE CHANCE OF THUNDERSTORMS ON MONDAY AFTERNOON...BUT
OTHERWISE LOOKING FOR DRY CONDITIONS ON MEMORIAL DAY. BY TUESDAY
EVENING THE SHORTWAVE RIDGE PUSHES TO THE EAST AS THE MAIN TROUGH OF
LOW PRESSURE VERY SLOWLY PUSHES THROUGH THE GREAT BASIN AND DESERT
SOUTHWEST. THE TROUGH EVENTUALLY REACHES THE FOUR CORNERS REGION BY
THURSDAY AFTERNOON. THE MAIN IMPACTS OF THE TROUGH WILL BE TO
PROVIDE A SLIGHT CHANCE OF SHOWERS OR THUNDERSTORMS...PRIMARILY OVER
THE HIGHER TERRAIN OF INYO...ESMERALDA...NYE AND LINCOLN COUNTIES ON
TUESDAY AND WEDNESDAY AFTERNOONS. SOME OF THE ENSEMBLE MEMBERS ARE
SHOWING ANOTHER LOW MOVING INTO THE CALIFORNIA COAST LATER IN THE
WEEK...BUT MOST OF THE ENSEMBLES ARE INDICATING THE DEVELOPMENT OF A
SHORTWAVE RIDGE...WITH TEMPERATURES TRENDING BACK TO OR SLIGHTLY
ABOVE THE SEASONAL NORMALS FOR THURSDAY AND FRIDAY.
&&

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

$$

UPDATE/AVIATION...SALMEN
PREV SHORT TERM...WOLCOTT
PREV LONG TERM...CZYZYK

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