Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 021656
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
956 AM PDT THU JUL 2 2015

.SYNOPSIS...A DISTURBANCE LIFTING NORTHEAST ACROSS SOUTHERN
CALIFORNIA WILL TRIGGER SHOWERS AND THUNDERSTORMS AT ANYTIME ACROSS
MUCH OF THE AREA TODAY. MOIST AND UNSTABLE AIR WILL CONTINUE TO
ALLOW FOR SHOWERS AND THUNDERSTORMS AROUND PRIMARILY IN THE
AFTERNOON AND EVENING HOURS THROUGH THE HOLIDAY WEEKEND. RELATIVE
HUMIDITY VALUES WILL RECOVER EACH NIGHT. TEMPERATURES WILL REMAIN
ABOVE NORMAL THROUGH THE WEEKEND WITH A SLIGHT DROP EARLY NEXT WEEK.
THERE MAY ALSO BE A GRADUAL DECREASE IN THE COVERAGE OF SHOWERS AND
THUNDERSTORMS BY THEN.
&&

.UPDATE...ACTIVITY ASSOCIATED WITH A WAVE WHICH WAS MOVING NORTHWEST
ACROSS THE CWA DECREASED EARLY THIS MORNING. IT LOOKS LIKE SOMEWHAT
DRIER AND MORE STABLE AIR MOVING IN BEHIND THE WAVE SO CONVECTION IS
NOT EXPECTED TODAY ACROSS THE FAR SOUTHERN PART OF THE FORECAST
AREA. ELSEWHERE IT WILL STILL BE FAIRLY MOIST AND UNSTABLE WITH THE
BEST CHANCE OF THUNDERSTORMS ACROSS THE NORTH AND OVER THE SPRING
MOUNTAINS ACCORDING TO MUCH OF THE 12Z MODEL DATA THAT HAS COME IN.
THIS IS IN LINE WITH THE INHERITED FORECAST AND NO UPDATES ARE
ANTICIPATED THIS MORNING. -HARRISON-

&&

.AVIATION...FOR MCCARRAN...SHRA/TSRA WILL END AFTER 15Z THIS
MORNING. THINGS SHOULD STAY DRY THIS AFTERNOON AND EVENING WITH
POSSIBLY AN ISOLATED SHRA/TSRA IN THE HIGHER MOUNTAINS AROUND THE
VALLEY. LOOK FOR IMPROVING CIGS AND VSBY THIS AFTERNOON WITH MAINLY
SCT CLOUDS AOA 15K FEET. WINDS WILL GENERALLY FAVOR DIURNAL
DIRECTIONAL TRENDS WITH GUSTS TO AROUND 20 KTS EXPECTED IN THE LATE
AFTERNOON AND EARLY EVENING.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...MAINLY SCT-BKN CLOUDS AOA 15K FEET WITH BASES AS LOW AS
6K-10K FEET IN AND NEAR ANY SHRA/TSRA. OUTSIDE OF THUNDERSTORM
ACTIVITY...WINDS SHOULD FAVOR TYPICAL DIURNAL TRENDS. &&

.PREV DISCUSSION...
306 AM PDT THU JUL 2 2015

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT.

THIS CONTINUES TO REMAIN A TOUGH MONSOON PATTERN TO NAIL DOWN MORE
THAN A FEW HOURS OUT. THAT SAID, WE ARE LIKELY GOING TO START THINGS
OFF ON THE INTERESTING SIDE TODAY BASED ON HOW THE RADAR HAS FILLED
BACK IN OVER THE LAST HOUR. A BROAD DISTURBANCE IN THE MID-LEVELS OF
THE ATMOSPHERE CONTINUES TO WORK NORTHWEST ACROSS SOCAL INTO CENTRAL
CALIFORNIA THIS MORNING WHICH COMBINED WITH A SOUTHEAST TO WEST
ORIENTED JET STREAM RUNNING AROUND 60 KTS+ AT 250 MB OFF THE
CALIFORNIA COAST WAS HELPING TO SERVE AS A LIFTING MECHANISM ON A
LARGER SCALE FOR CONVECTION THIS MORNING. WE REALLY NEVER SAW
EVERYTHING SHUT DOWN YESTERDAY EVENING AND THUS THE ACTIVITY
PRESENTLY OVER SOUTHERN NEVADA WAS FED OFF WHAT WAS GENERATED ACROSS
NORTHWEST ARIZONA LATER YESTERDAY EVENING. THE HRRR DID A GOOD JOB
LAST EVENING LATCHING ONTO THIS AND THUS NOW THAT WE ARE SEEING IT
BECOME REALITY, I WENT AHEAD AND SIGNIFICANTLY INCREASED POPS FOR
THE REST OF THIS MORNING ACROSS MUCH OF CLARK COUNTY, INCLUDING THE
LAS VEGAS VALLEY. THE MAIN HAZARDS WILL BE LIGHTNING (WHICH HAS BEEN
QUITE IMPRESSIVE TO VIEW OUT THE WINDOW WITH THE SIZE OF THE CG
STRIKES), DOWNPOURS POTENTIALLY CAUSING MINOR FLOODING AND WIND
GUSTS. ONCE WE MOVE THROUGH THE MORNING, THIS ACTIVITY SHOULD WORK
WEST TOWARD SOUTHERN NYE AND SOUTHERN INYO COUNTIES. AS A RESULT,
THE NORTHWEST PART OF THE CWFA SHOULD STAY RATHER CLOUDY TODAY AND
HIGHS WERE LOWERED OVER THAT AREA A FEW DEGREES. ACROSS LAS VEGAS,
ONCE WE SEE SHOWERS AND THUNDERSTORMS END BY LATER THIS MORNING OR
AT THE LATEST EARLY THIS AFTERNOON WE WILL PROBABLY BE WORKED OVER
ENOUGH THAT THINGS SHOULD QUIET DOWN THIS AFTERNOON. HOWEVER, WE MAY
BE A BIT TOO MOIST AND CLEAR SLOWLY ENOUGH THAT WE STILL MAY BE TOO
WARM ON THE HIGH TEMP FOR TODAY.

THE FLOW ALOFT TODAY REMAINS SOUTHEAST AND AS A RESULT, POPS WERE
KEPT DOWN ACROSS MOHAVE COUNTY, WHICH MAY SEE SOME ACTIVITY THIS
MORNING AND THIS AFTERNOON MAINLY IN THE PLATEAU REGION. FURTHER
SOUTHWEST IN MOHAVE COUNTY AND EXTENDING INTO SOUTHERN SAN
BERNARDINO COUNTY IT LOOKS TOO STABLE TODAY TO SEE MUCH AND POPS
WERE TRIMMED BACK. WITH THE FLOW STAYING SOUTHEAST ALOFT, THERE IS
LESS OF A RISK THIS EVENING FOR MUCH ACTIVITY TO WORK INTO THE LAS
VEGAS VALLEY OR COLORADO RIVER VALLEY BELOW HOOVER DAM. THE MOST
ACTIVE AREAS THIS EVENING LOOK TO BE TO THE NORTH AND NORTHWEST OF
LAS VEGAS.

OVERALL WE REMAIN WITH A ROAD RIDGE ALOFT ACROSS THE AREA THAT SITS
AROUND THROUGH THE HOLIDAY WEEKEND. WE LOOK TO SEE AN AREA OF NVA
ENTER MUCH OF THE CWFA ON FRIDAY WHICH WOULD FAVOR A LACK OF
CONVECTIVE ACTIVITY. FOR NOW, POPS WERE LEFT ALONE BUT MAY NEED TO
BE LOWERED. THE BEST ODDS LOOK TO BE OVER THE SOUTHERN GREAT BASIN
WHERE INSTABILITY AND CAPE IS STILL NOTED AND ACTIVITY POPS UP OVER
THE TERRAIN DRIVEN BY HEATING.

AN AREA OF LOW PRESSURE IN THE MID/UPPER LEVELS OFF THE BAJA IS
SLATED TO MOVE NORTH TO OFF SOCAL ON FRIDAY AND THEN OFF THE COAST
OF CENTRAL CALIFORNIA ON SATURDAY. THIS FEATURE SHOULD LIKELY HELP
SHOWERS AND THUNDERSTORMS DEVELOP OVER THE SOUTHERN SIERRA AND THUS
WE SHOW AN INCREASE IN POPS HERE. ELSEWHERE IT LOOKS STABLE ENOUGH
THAT VERY LITTLE ACTIVITY MAY GET GOING WITH WHATEVER THAT CAN BE
DRIVEN BY HEATING AND OVER THE HIGHEST TERRAIN. THUS FOR MOST FOLKS
ON THE 4TH IT SHOULD BE DRY BUT STILL ABOVE AVERAGE FOR TEMPS WITH
SLIGHTLY HIGHER THAN AVERAGE HUMIDITY (SURFACE DEWPOINTS BETWEEN 40
AND 50 DEGREES).

BY SUNDAY THE FLOW ALOFT STARTS TO GO MORE SOUTH TO SOUTHWEST WHICH
WILL RESULT IN THINGS STARTING TO DRY OUT MORE, ESPECIALLY IN THE
SOUTHWEST AND SOUTH-CENTRAL CWFA. POPS WERE KEPT MAINLY FOR THE
SOUTHERN GREAT BASIN, WHICH LOOKS TO HAVE THE BEST SHOT AT A SHOWER
OR THUNDERSTORM AS WELL AS THE SPRING MOUNTAINS AND EASTERN MOHAVE
COUNTY.

I DID LOWER LOW TEMPS A TOUGH SATURDAY AND SUNDAY NIGHTS AS WE DRY
OUT AND SEE HEIGHTS LOWER A LITTLE AS WELL.

.LONG TERM...MONDAY THROUGH THURSDAY.

IT APPEARS THE FIRST BREAK IN THE MONSOONAL PATTERN WILL OCCUR EARLY
NEXT WEEK AS AN INCREASINGLY DRY SOUTHWEST FLOW SPREADS INLAND
ACROSS SOUTHEAST CALIFORNIA...SOUTHERN NEVADA AND NORTHWEST ARIZONA.
THIS DRY AND STABLE FLOW IS ASSOCIATED WITH A PACIFIC TROUGH THAT
APPROACHES THE WEST COAST THEN PARKS OFFSHORE MUCH OF NEXT WEEK.
THIS PATTERN SHOULD SCOUR OUT ANY LINGERING MOISTURE ACROSS OUR
FORECAST AREA BY WEDNESDAY AND MAYBE AS EARLY AS TUESDAY. I WILL
KEEP THE MENTION OF A SLIGHT CHANCE OF THUNDERSTORMS MONDAY AND
TUESDAY MAINLY OVER THE SOUTHERN SIERRA...CENTRAL NEVADA AND
NORTHWEST ARIZONA ZONES MONDAY AND TUESDAY. TEMPERATURES WILL BE
RUNNING CLOSE TO NORMAL...BUT THAT IS STILL QUITE HOT WITH HIGHS
GENERALLY 105-110 DEGREES ACROSS THE MOJAVE DESERT AND COLORADO
RIVER REGION.
&&

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

$$

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


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