Dust Devil in Nevada, July 15, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
1050 AM PDT WED JUL 15 2015

.SYNOPSIS...DRY CONDITIONS WITH NEAR NORMAL TEMPERATURES WILL
PERSIST THROUGH FRIDAY BEFORE SOME CHANGES BEGIN TO TAKE PLACE FOR
THE WEEKEND. MOISTURE IS EXPECTED TO GET PUSHED NORTH BY HURRICANE
DOLORES LATE FRIDAY INTO SATURDAY AND REMAIN IN PLACE ACROSS THE
AREA THROUGH MONDAY. THIS SHOULD RESULT IN PLENTY OF CLOUDS ALONG
WITH THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS...SOME OF WHICH
COULD PRODUCE LOCALLY HEAVY RAIN.

&&

.UPDATE...RECENT ANALYSES AND 12Z MODELS INDICATE THE AIR MASS OVER
THE FORECAST AREA HAS DRIED IN THE PAST 24 HOURS WITH PW VALUES
LOWERING AROUND A QUARTER INCH AT PW SITES. A MINOR UPDATE WAS MADE
TO REDUCE THE 15 POPS IN NORTHEAST MOHAVE COUNTY NEAR PIPE SPRING
THIS AFTERNOON. ALSO...WINDS WERE UPDATED BASED ON THE LATEST
OBSERVATIONS AND HRRR FORECAST. WILL BE TAKING A CLOSE LOOK AT
MEDIUM RANGE AND ENSEMBLE GUIDANCE FOR THE POTENTIAL MOISTURE INFLUX
THIS WEEKEND. CONFIDENCE IS STILL LOW IN NORTHWARD EXTENT OF THE
MOISTURE DUE TO A TROUGH DROPPING INTO THE NORTHWEST STATES.
&&

.AVIATION...FOR MCCARRAN...LIGHT EAST-SOUTHEAST WIND COMPONONET WILL
GIVE WAY TO A PUSH OF STRONGER SOUTH-SOUTHWEST WINDS AROUND
20Z...GIVE OR TAKE AN HOUR. WIND SPEEDS DURING THE AFTERNOON WILL BE
IN THE 10-15 KT RANGE WITH GUSTS AS HIGH AS 25 KTS.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...DRY AND CLEAR CONDITIONS EXPECTED ACROSS THE AREA WITH
EXCEPTION OF SOME ISOLATED BUILD UPS IN THE SIERRA WEST OF KBIH.
SOUTHERLY WINDS OF 10-15KT WITH GUSTS TO 25KTS EXPECTED DURING THE
AFTERNOON HOURS.
&&

.PREV DISCUSSION...
240 AM PDT WED JUL 15 2015

.SHORT TERM...THROUGH THURSDAY NIGHT.

FAIRLY TRANQUIL CONDITIONS EXPECTED IN THE SHORT TERM THANKS TO A
DRY SOUTHWESTERLY FLOW OVER THE AREA COURTESY OF A WEAK UPPER LEVEL
TROUGH OVER CALIFORNIA. THE ONLY EXCEPTION TO THE DRY CONDITIONS
WILL BE ACROSS THE HIGHEST TERRAIN OF THE SIERRA WHERE AND ISOLATED
SHOWER OR THUNDERSTORM COULD DEVELOP DURING THE AFTERNOON AND
EVENING HOURS. HOWEVER...ANY RAINFALL IS EXPECTED TO BE QUITE LIGHT.
I ALSO ADDED VERY SLIGHT POPS FOR FAR NORTHEAST MOHAVE COUNTY WHICH
SAW SOME ACTIVITY MONDAY AND MAY HAVE JUST ENOUGH INSTABILITY TO
FOSTER A FEW CUMULUS BUILD UPS AND PERHAPS AND ISOLATED SHOWER OR
STORM THIS AFTERNOON.

OTHERWISE...DRY CONDITIONS WILL PERSIST THROUGH THURSDAY WITH NEAR
NORMAL TEMPERATURES. WINDS WILL BE BREEZY AT TIMES DURING THE
AFTERNOON HOURS EACH DAY.

.LONG TERM...FRIDAY THROUGH TUESDAY.

AFTER TWO DAYS OF GOOD MODEL CONTINUITY AND AGREEMENT SOME
DIFFERENCES CREPT INTO THE 00Z CYCLE. THE DIFFERENCES REVOLVE AROUND
THE HANDLING OF A TROUGH DROPPING SOUTH INTO THE NORTHERN
ROCKIES/PAC NW OUT OF WESTERN CANADA IN THE COMING DAYS.

00Z GFS AND ABOUT HALF OF ITS ENSEMBLE MEMBERS PROGRESS THE TROUGH
FURTHER SOUTHEAST INTO THE GREAT BASIN WHICH WOULD KEEP A STRONGER
SOUTHWEST FLOW ACROSS THE GREAT BASIN BASICALLY KEEPING ANY TROPICAL
MOISTURE INTRUSION CONFINED TO THE SOUTHERN FORECAST AREA, CLARK,
MOHAVE AND SAN BERNARDINO COUNTIES. EVEN THOUGH THE TROPICAL
MOISTURE DOES NOT MAKE IT AS FAR AS LINCOLN COUNTY THERE STILL LOOKS
TO BE A CHANCE OF SHOWERS OR THUNDERSTORMS ASSOCIATED WITH THE
TROUGH PASSAGE SUNDAY. THERE WAS LITTLE CHANGE WITH THE 00Z ECMWF
FROM PREVIOUS RUNS.

FOR NOW, NOT JUMPING ON THIS ONE RUN OF THE GFS SO ONLY MADE SOME
MINOR ADJUSTMENTS. HOPING FOR BETTER MODEL CLARITY IN THE COMING
DAYS.

&&

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

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

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