Severe Thunderstorm Warning 25, NWS Las Vegas, NV

284 
WWUS55 KVEF 182110
SVSVEF

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE LAS VEGAS NV
210 PM MST MON AUG 18 2014

AZC015-182119-
/O.CAN.KVEF.SV.W.0025.000000T0000Z-140818T2130Z/
MOHAVE AZ-
210 PM MST MON AUG 18 2014

...THE SEVERE THUNDERSTORM WARNING FOR EXTREME NORTHEASTERN MOHAVE
COUNTY IS CANCELLED...

DOPPLER RADAR INDICATES THE THUNDERSTORM THAT PROMPTED THE WARNING 
HAS WEAKENED CONSIDERABLY AND SEVERE WEATHER IS NO LONGER EXPECTED 
FROM THIS STORM.

LAT...LON 3680 11261 3671 11261 3670 11262 3657 11263
      3649 11266 3646 11285 3678 11295 3681 11260
TIME...MOT...LOC 2109Z 172DEG 11KT 3665 11276

$$

JS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
918 AM PDT MON AUG 18 2014

.SYNOPSIS...A LOW PRESSURE SYSTEM DROPPING DOWN THE WEST COAST WILL
HELP DRAW MONSOON MOISTURE NORTH...LEADING TO A CHANCE OF
THUNDERSTORMS OVER EASTERN CALIFORNIA...SOUTHERN NEVADA AND
NORTHWEST ARIZONA TODAY INTO TUESDAY. TEMPERATURES WILL COOL SOME
EACH DAY INFLUENCED BY THE MOISTURE AND NEARBY LOW PRESSURE SYSTEM.
&&

.UPDATE...THUNDERSTORMS ROUGHLY ALONG INTERSTATE 40 FROM ESSEX TO
NORTH OF YUCCA WERE MOVING NORTH AND SLOWLY WEAKENING. RAISED POPS
AND CLOUD COVER IN THE PATH OF THE STORMS.
&&

.PREV DISCUSSION...
252 AM PDT MON AUG 18 2014

.SHORT TERM...THROUGH TUESDAY NIGHT
AN OUTFLOW BOUNDARY OUT OF SOUTHWEST ARIZONA MOVED THROUGH LAKE
HAVASU CITY AROUND MIDNIGHT. THE BOUNDARY HAS CONTINUING TO PUSH
WEST THROUGH SOUTHERN SAN BERNARDINO COUNTY, ALTHOUGH WESTWARD
MOMENTUM LOOKS TO BE SLOWING AS IT NEARS THE MORONGO BASIN.
ELSEWHERE SKIES ARE CLEAR.

MOISTURE OVER ARIZONA WILL CONTINUE TO FLOW NORTHWARD INTO THE
MOJAVE DESERT AND SOUTHERN GREAT BASIN SOUTHEAST TODAY AROUND HIGH
PRESSURE CENTERED NEAR THE FOUR CORNERS. A MID-LEVEL SHORTWAVE
TROUGH NEAR THE SOUTHERN CALIFORNIA COAST WILL SLOWLY SHIFT INLAND
ACROSS THE AREA TONIGHT IN RESPONSE TO A CLOSED LOW LOW DROPPING
DOWN THE PAC NW COAST. THIS SHORTWAVE TROUGH WILL PROVIDE SOME
ADDITIONAL DYNAMICS IN THE FORM OF DIVERGENCE ALOFT ASSOCIATED WITH A
70 KNOT JET OVERHEAD. GOING TO KEEP ANY MENTION OF ISOLD/SCTD
THUNDERSTORMS EAST OF A YUCCA VALLEY-PAHRUMP-RACHEL LINE TODAY. THE
NORTHWEST CWA WILL STAY THUNDERSTORM FREE.

DID INCREASE POPS FOR LINCOLN, ERN CLARK, ERN SAN BERNARDINO AND
MOHAVE COUNTIES TONIGHT INTO TUESDAY AS HI-RES MODELS SIMILAR
SHOWING GOOD CLUSTERING FOR THUNDERSTORM POTENTIAL. WITH UPPER LOW
MOVING SOUTH OVER CENTRAL CALIFORNIA TUESDAY AFTERNOON DECIDED TO
INTRODUCE A SLIGHT CHANCE OF THUNDERSTORMS TO THE EASTERN SIERRA
SLOPES. LOWERING HEIGHTS, HIGHER HUMIDITY/CLOUD COVER WILL PRODUCE
NEAR NORMAL TEMPERATURES TODAY FOLLOWED BY BELOW NORMAL VALUES
TUESDAY.

.LONG TERM...WEDNESDAY THROUGH MONDAY NIGHT.

THIS IS NOT THE HIGHEST CONFIDENT OF FORECASTS FOR THE LATE WEEK
PERIOD AS THE LATEST OPERATIONAL MODELS CONTINUE TO SHOW A LARGE
SPREAD IN HOW THEY HANDLE THE MAJOR FEATURES IN THIS PERIOD. A
MID/UPPER LEVEL LOW IS FORECAST TO DROP INTO SOCAL ON WEDNESDAY
WHICH WILL CONTINUE TO PULL MOISTURE ON NORTH. HOW FAR WEST THIS
MOISTURE GETS IS QUESTIONABLE BUT GIVEN THE POSITION OF THE LOW NEAR
LOS ANGELES IT IS POSSIBLE SHOWERS AND THUNDERSTORMS COULD DEVELOP
AS FAR WEST AS A MORONGO VALLEY TO MT CHARLESTON TO PIOCHE LINE AND
A SLIGHT CHANCE FOR THUNDERSTORMS WAS PLACED IN FROM HERE ON EAST.
WORTH WATCHING WILL BE THE POTENTIAL FOR A MOIST-DRY BOUNDARY (OR A
SO-CALLED DESERT DRY LINE) WHICH TENDS TO SERVE AS FOCUS FOR SHOWERS
AND THUNDERSTORMS TO DEVELOP.

THE MAIN ISSUE IS IN THE THURSDAY THROUGH SATURDAY PERIOD AS THE
AFOREMENTIONED LOW IS EITHER PUSHED EAST BY A MID/UPPER LEVEL TROUGH
THAT DROPS INTO NORTHERN NEVADA OR IS NOT PICKED UP AND FLOATS
AROUND EITHER OFF TO THE WEST (GEM) OR IS SLOWER TO EJECT (ECMWF AND
DGEX) VERSUS THE FASTER OPERATIONAL GFS. AT THIS TIME, CONFIDENCE IS
NOT THE HIGHEST IN ANY ONE SOLUTION. THE FORECAST THUS CONTINUES A
BLEND OF THE VARIOUS SOLUTIONS, KEEPING A CHANCE FOR SHOWERS AND
THUNDERSTORMS IN FOR MAINLY THE AFTERNOON AND EVENING HOURS SOUTH OF
INTERSTATE 15 WITH THE HIGHEST CHANCES IN MOHAVE COUNTY. BY SUNDAY,
WE SHOWED A DRYING TREND AS ALL MODELS SHOW THE LOW OFF EITHER WELL
ENOUGH TO THE WEST OR EAST.

HIGH TEMPS WERE LOWERED SEVERAL DEGREES DUE TO THE LOW AND EXPECTED
INCREASED CLOUD COVER FROM WEDNESDAY THROUGH FRIDAY WITH HIGHS AS
MUCH AS 6 TO 9 DEGREES BELOW NORMAL. TEMPS SHOULD THEN WARM BACK
CLOSER TO NORMAL OVER THE WEEKEND AND BASED ON FORECAST SOUNDINGS,
WE WENT ABOVE STATISTICAL GUIDANCE AND WITH THE WARMER END OF BIAS
CORRECTED CONS MODELS.  DEWPOINTS WERE ALSO RAISED SEVERAL DEGREES
TO BETTER BLEND WITH NEIGHBORING OFFICES.

.AVIATION...FOR MCCARRAN...THERE IS A SLIGHT CHANCE THAT
THUNDERSTORMS WILL DEVELOP NEAR THE TERMINAL AREA THIS AFTERNOON AND
EVENING BUT CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE IN THE TAF.
OTHERWISE...EXPECT PERIODS OF EAST TO SOUTHEAST WINDS IN THE LATE
MORNING AND EARLY AFTERNOON ALONG WITH INCREASING CLOUDS ABOVE 10
KFT AGL. EVEN IF STORMS ARE NOT NEAR THE TERMINALS WINDS COULD
BECOME GUSTY AND ERRATIC IN DIRECTION. THERE WILL BE CHANCES FOR
THUNDERSTORMS TODAY IN ALL CORRIDORS AND TUESDAY IN THE MORMON MESA
AND PEACH SPRINGS CORRIDORS.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...ISOLATED/SCATTERED THUNDERSTORMS CAN BE EXPECTED TODAY
THROUGH TUESDAY OVER EASTERN SAN BERNARDINO COUNTY CALIFORNIA...
SOUTHEAST NEVADA AND NORTHWEST ARIZONA. CEILING MAY LOWER TO
5-7K FT IN THUNDERSTORMS ESPECIALLY OVER NORTHWEST ARIZONA. WINDS
WILL FOLLOW TYPICAL DIURNAL TRENDS EXCEPT BE GUSTY AND ERRATIC
NEAR STORMS

.SPOTTER INFORMATION STATEMENT...SPOTTERS SHOULD REPORT INSTANCES OF
FLASH FLOODING...STRONG GUSTY WINDS...HAIL...AND BLOWING DUST TODAY
THROUGH TUESDAY.
&&

MORGAN/PIERCE/STACHELSKI

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