Flash Flood and Hail in California, July 8 to 9, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
1000 AM PDT WED JUL 8 2015

.SYNOPSIS...SOMEWHAT DRIER AIR WILL RESULT IN MORE LIMITED SHOWER
AND THUNDERSTORM COVERAGE TODAY WITH ACTIVITY MAINLY CONFINED TO
NORTHERN MOHAVE...ESMERALDA AND LINCOLN COUNTIES AS WELL AS THE
HIGHER TERRAIN OF INYO COUNTY. AN AREA OF LOW PRESSURE WILL MOVE
ACROSS THE AREA ON THURSDAY TRIGGERING SHOWERS AND THUNDERSTORMS
MAINLY NORTH OF INTERSTATE 15. A FEW SHOWERS AND THUNDERSTORMS WILL
LINGER IN INYO AND ESMERALDA COUNTIES ON FRIDAY. OTHERWISE EXPECT A
DRY WEEKEND AREAWIDE WITH SHOWERS AND THUNDERSTORMS POSSIBLY
RETURNING TO MOHAVE COUNTY ON TUESDAY. TEMPERATURES WILL REMAIN
BELOW NORMAL. &&

.UPDATE...DRIER AIR IS TRYING TO WORK INTO THE REGION FROM THE
SOUTHWEST...BUT IT STILL LOOKS LIKE THERE IS ENOUGH MOISTURE FOR
SHOWERS AND THUNDERSTORMS TO DEVELOP AGAIN TODAY. THE 12Z MODELS ARE
INDICATING AN ENHANCED AREA OF VORTICITY PUSHING NORTHWARD THROUGH
SAN BERNARDINO COUNTY WHICH HAS ALREADY HELPED GENERATE A FEW
THUNDERSTORMS OVER EASTERN SAN BERN...NYE AND MOHAVE COUNTIES.
SHEAR VALUES ARE ALSO A BIT HIGHER TODAY AND STORM MOTION IS AROUND
25KTS SO FLASH FLOODING IS NOT EXPECTED TO BE THE MAIN CONCERN
TODAY...HOWEVER GUSTY WINDS AND HAIL WILL BE. BY AFTERNOON THE MAIN
FOCUS WILL SHIFT TO THE NORTHERN PORTIONS OF THE CWA WHERE THERE
BETTER MOISTURE AND DYNAMICS. MADE SEVERAL CHANGES TO INCREASE POPS
ACROSS MANY AREAS.

.AVIATION...FOR MCCARRAN...EXPECT WINDS TO TREND TOWARD TYPICAL
DIURNAL DIRECTIONS THROUGH WEDNESDAY EVENING. GUSTS OF 20-25 KTS ARE
POSSIBLE WEDNESDAY AFTERNOON AND EVENING. MAINLY SCT-BKN CLOUDS AOA
12K FEET TONIGHT WITH FEW-SCT CLOUDS AOA 12K FEET ON WEDNESDAY.
THERE WILL BE A FEW THUNDERSTORMS DEVELOP OVER MAINLY THE MOUNTAINS
AND THE EASTERN APPROACH CORRIDORS WHICH COULD PRODUCE GUSTY WINDS
IN THE VALLEY. THERE IS A CHANCE FOR AFTERNOON AND EVENING SHRA/TSRA
AGAIN ON THURSDAY AFTER 20Z AND BEFORE 04Z FRIDAY AS A SYSTEM MOVES
ACROSS THE AREA. DRY CONDITIONS ARE EXPECTED TO RETURN FOR THE
WEEKEND.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...WINDS WILL FAVOR TYPICAL DIURNAL DIRECTIONAL TRENDS
THROUGH WEDNESDAY EVENING. MAINLY SCT-BKN CLOUDS NORTHEAST OF THE
AFOREMENTIONED LINE TONIGHT AOA 12K FEET. FEW-SCT CLOUDS AOA 12K
FEET ON WEDNESDAY. ISOLATED SHRA/TSRA MAINLY AFTER 20Z WEDNESDAY AND
BEFORE 04Z THURSDAY IN AND AROUND KBIH MAINLY IN THE MOUNTAINS AND
IN FAR NORTHERN LINCOLN COUNTY.
&&

PREV DISCUSSION
249 AM PDT WED JUL 8 2015

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT.

DRY AIR HAS FINALLY WORKED INTO MUCH OF THE AREA FROM THE SOUTHWEST
WITH THE SURFACE DEWPOINT NOW INTO THE LOWER 30S IN LAS VEGAS. GIVEN
THIS, AND THAT WE WILL STAY IN A GENERAL SOUTHWEST FLOW ALOFT TODAY,
THERE IS LITTLE POTENTIAL FOR SHOWER AND THUNDERSTORM DEVELOPMENT
ACROSS MUCH OF THE AREA TODAY. AS A RESULT, EXPECT A DRY DAY WITH
HIGH TEMPS NEAR OR SLIGHTLY LOWER THAN WHAT WE SAW ON TUESDAY. TEMPS
WILL LOWER MORE IN THE WESTERN CWFA DUE TO THE COMBINATION OF HEIGHT
FALLS FROM THE APPROACHING MID/UPPER LEVEL LOW (LOCATED ON WATER
VAPOR THIS MORNING NEAR MONTEREY, CALIFORNIA) AS WELL AS SOME MARINE
AIR GETTING PUSHED IN THROUGH THE COASTAL PASSES. AN OVER 100 KT+
JET AT 250 MB (WHICH IS 3 TO 4 STANDARD DEVIATIONS ABOVE NORMAL FOR
THIS TIME OF YEAR) WILL MOVE ACROSS SOCAL TODAY. THIS JET COMBINED
WITH WELL-ALIGNED WIND DIRECTION WITH HEIGHT WILL ALLOW FOR STRONGER
WINDS ALOFT TO MIX DOWN TO THE SURFACE THIS AFTERNOON AND EVENING
OVER THE MOJAVE DESERT. AS A RESULT, EXPECT SOUTHWEST WINDS GUSTING
TO 25 TO 35 MPH. THESE WINDS SHOULD DECREASE SLIGHTLY LATER THIS
EVENING.

AS FAR AS CONVECTION GOES TODAY, THERE WILL BE TWO SMALL AREAS TO
WATCH. ONE WILL BE IN NORTHERN LINCOLN COUNTY WHERE MOISTURE IS NOT
ENTIRELY SCOURED OUT YET AND SHOWERS AND THUNDERSTORMS ARE STILL
GOING ON EARLY THIS MORNING. WE MAY SEE MORE ACTIVITY HERE TRY TO
DEVELOP AGAIN THIS AFTERNOON. THE OTHER AREA WILL BE OVER INYO AND
WESTERN ESMERALDA COUNTY, WHICH DID DRY OUT YESTERDAY, BUT WILL BE
CLOSE ENOUGH TO THE CENTER OF THE APPROACHING LOW THAT ADDITIONAL
MOISTURE ASSOCIATED WITH THE LOW CENTER MAY GET PUSHED BACK ON IN.
IN ADDITION, THE COLD AND UNSTABLE AIR ALOFT ASSOCIATED WITH THE LOW
WILL HELP FUEL THUNDERSTORM DEVELOPMENT. ACTIVITY SHOULD GET GOING
BY LATE THIS MORNING INTO THIS AFTERNOON AND GIVEN THE SOUTHWEST
FLOW ALOFT HAVE THE POTENTIAL TO WORK INTO THE OWENS, FISH LAKE AND
DEEP SPRINGS VALLEYS OFF THE HIGHER TERRAIN.

THE AFOREMENTIONED MID/UPPER LEVEL LOW IS SLATED TO MOVE EAST AND
CROSS THE AREA ON THURSDAY. THIS WILL PUSH THE JET STREAM OVER THE
SOUTHERN PART OF THE AREA WHICH WILL ONCE AGAIN RESULT IN BREEZY
SOUTH TO SOUTHWEST WINDS IN THE AFTERNOON AND EVENING HOURS. THERE
IS A TONGUE OF HIGHER PWAT VALUES NEAR AN INCH FORECAST TO WORK UP
THE COLORADO RIVER VALLEY TOWARD LAS VEGAS AND THE CENTER OF THE LOW
WILL ALSO HELP TO SPREAD IN MOISTURE INTO THE NORTHERN CWFA. GIVEN
THE BETTER LIFT FROM THE JET AND THE LOW AND INCREASED MOISTURE,
THERE IS A BETTER SHOT AT SHOWERS AND THUNDERSTORMS DEVELOPING
ACROSS THE AREA, MAINLY NORTH OF INTERSTATE 15 IN THE AFTERNOON AND
EVENING HOURS. WRF LI'S DROP TO AN IMPRESSIVE -5 OVER THE SPRING
MOUNTAINS AND SURFACE COMPUTED CAPE VALUES OVER 400 J/KG ARE NOTED
IN LINCOLN COUNTY AS WELL AS OVER THE SOUTHERN SIERRA. GIVEN THE
SYNOPTIC SET-UP, WE MAY SEE SOME MORE ORGANIZED STORMS TRY TO FORM
WHICH WOULD INCREASE THE POTENTIAL FOR GUSTY WINDS OR HAIL AS WELL
AS MORE EFFICIENT RAIN PRODUCERS WOULD COULD TRIGGER FLASH FLOODING.
OTHERWISE TEMPS WILL DROP A FEW MORE DEGREES.

MUCH DRIER AIR WILL MOVE IN BEHIND THE DEPARTING LOW FOR FRIDAY
ALTHOUGH WE WILL REMAIN IN A BROAD MID/UPPER LEVEL TROUGH. LINGERING
ENERGY AND MOISTURE MAY TOUCH OFF A FEW SHOWERS AND THUNDERSTORMS IN
INYO AND ESMERALDA COUNTIES IN THE AFTERNOON/EVENING. OTHERWISE LOOK
FOR ANOTHER DAY OF ENJOYABLE BELOW NORMAL TEMPERATURES WITH LOWER
HUMIDITY. WEAKER UPPER LEVEL SUPPORT WILL ALSO RESULT IN LOWER
WINDS.

.LONG TERM...SATURDAY THROUGH WEDNESDAY.

DRY SOUTHWEST FLOW ASSOCIATED WITH A MEAN TROUGH ALONG THE WEST
COAST WILL KEEP THE FORECAST AREA STORM FREE SATURDAY...PROVIDING
THE FIRST BREAK IN THE MONSOON PATTERN FOR THIS SEASON. THE LATEST
ECMWF KEEPS THIS SOUTHWEST FLOW ACROSS THE FORECAST AREA THROUGH
WEDNESDAY WHILE THE GFS INDICATES THE POSSIBILITY OF SOUTHERLY FLOW
BRINGING MOISTURE UP INTO NORTHWEST ARIZONA AND NEAR THE NEVADA
BORDER SUNDAY THROUGH WEDNESDAY. A SLIGHT CHANCE OF THUNDERSTORMS
WILL REMAIN FOR THOSE ZONES EARLY NEXT WEEK UNTIL WE SEE WHICH HAS
MORE INFLUENCE...THE WEST COAST TROUGH OR THE HIGH FORECAST TO BE
OVER NEW MEXICO AND TEXAS. TEMPERATURES WILL STAY BELOW NORMAL
THROUGH THE WEEKEND THEN INCREASE A DEGREE OR TWO EACH DAY EARLY
NEXT WEEK.
&&

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

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

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