877  
FXUS65 KVEF 180201 AAA  
AFDVEF  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LAS VEGAS NV  
700 PM PDT TUE JUL 17 2018  
   
SYNOPSIS
 
HOT AND HUMID CONDITIONS WILL CONTINUE THROUGH MID WEEK  
WITH THUNDERSTORMS POSSIBLE ACROSS MUCH OF THE FORECAST AREA  
THROUGH THE END OF THE WEEK, ESPECIALLY IN THE HIGHER TERRAIN.  

 
   
UPDATE...AT 7 PM
 
SCATTERED THUNDERSTORMS WERE PRIMARILY CONFINED  
TO PARTS OF LINCOLN COUNTY AND NORTHERN MOHAVE COUNTY WITH A COUPLE  
OF WEAK CELLS IN WESTERN CLARK COUNTY. THE ACTIVITY IN LINCOLN  
COUNTY IS EXPECTED TO DRIFT TO THE SOUTHEAST INTO THE NORTHEAST  
PORTION OF CLARK COUNTY OVER THE NEXT FEW HOURS. IN GENERAL, THERE  
SHOULD BE A DOWNWARD TREND IN MOST OF THIS ACTIVITY AFTER SUNSET.  
UPDATES ARE OUT. -SALMEN-  

 
   
PREVIOUS DISCUSSION...231 PM PDT
 
 
   
SHORT TERM
 
THROUGH THURSDAY NIGHT.  
 
TWO PRIMARY WEATHER FEATURES INFLUENCING OUR WEATHER ARE HIGH  
PRESSURE CURRENTLY CENTERED OVER THE CENTRAL CALIFORNIA COASTLINE  
AND AN INVERTED TROUGH MOVING ACROSS SOUTHERN ARIZONA AND NORTHERN  
MEXICO. OVERNIGHT, THE HIGH PRESSURE CENTER MOVES INLAND OVER  
CENTRAL CALIFORNIA AND THE INVERTED TROUGH PUSHES INTO SOUTHERN  
CALIFORNIA. ANY STORMS THAT SURVIVE OR DEVELOP OVERNIGHT, WILL  
GENERALLY MOVE TO THE SOUTHWEST ACROSS MOHAVE COUNTY AND SOUTHERN  
SAN BERNARDINO COUNTY. THE LAST SEVERAL RUNS OF THE HRRR HAS TRENDED  
AWAY FROM BRINGING STORMS OUT OF LINCOLN COUNTY INTO CLARK COUNTY.  
LEFT A CHANCE OF SHOWERS/STORMS IN THE SPRING MOUNTAINS AND SHEEP  
RANGE THIS EVENING BUT KEPT THE LAS VEGAS VALLEY DRY BASED ON THE  
LATEST HRRR FORECAST.  
 
ON WEDNESDAY, HIGH PRESSURE SHIFTS EAST INTO CENTRAL NEVADA WHILE  
THE INVERTED TROUGH LIFTS NORTHWEST ACROSS SAN BERNARDINO COUNTY.  
THIS TRACK WILL BRING HIGHER MOISTURE AND INCREASING INSTABILITY  
ACROSS THE SIERRA AND INYO COUNTY. MORE THAN SUFFICIENT MOISTURE AND  
WEAK INSTABILITY ELSEWHERE WILL GIVE MOST AREAS A CHANCE OF SHOWERS  
AND STORMS WEDNESDAY AFTERNOON/EVENING WITH THE POSSIBLE EXCEPTION  
OF SAN BERNARDINO COUNTY WHICH WILL LIE IN AN UNFAVORABLE REGION OF  
DOWNWARD MOTION BEHIND THE TROUGH.  
 
THE HIGH IS FORECAST TO RE-POSITION OVER THE FOUR CORNERS AREA ON  
THURSDAY WITH A GENERAL SOUTHEASTERLY FLOW SETTING UP ACROSS THE  
FORECAST AREA. ANY EMBEDDED DISTURBANCES OR DECAYING MCS THAT FORM  
SOUTH-SOUTHEAST OF OUR AREA WEDNESDAY NIGHT COULD BECOME A PLAYER  
INFLUENCING CONVECTIVE ACTIVITY THURSDAY.  
 
AN EXCESSIVE HEAT WARNING IS IN EFFECT THROUGH WEDNESDAY EVENING FOR  
THE OWENS VALLEY AND ESMERALDA COUNTY WITH A EXCESSIVE HEAT ADVISORY  
IN EFFECT FOR THE WHITE MOUNTAINS OF INYO COUNTY. HOT AND HUMID  
CONDITIONS ARE EXPECTED WITH SKY CONDITIONS AND TEMPERATURES GREATLY  
INFLUENCED BY THE AMOUNT OF CLOUDS SPREAD ACROSS THE REGION FROM  
DECAYING OVERNIGHT CONVECTION.  
   
LONG TERM
 
FRIDAY THROUGH TUESDAY.  
 
BY FRI, AN UPPER LEVEL TROUGH OVER NW CANADA AND THE NW PACIFIC WILL  
HELP NUDGE THE RIDGE OVERHEAD EASTWARD, EVENTUALLY MOVING IT OVER  
NEW MEXICO AND TEXAS BY SATURDAY. THE EASTWARD PROPAGATION OF THE  
HIGH SHOULD RESULT IN SOME MID-LEVEL DRY AIR OFF THE SOCAL COAST TO  
FILTER IN ACROSS SOUTHWESTERN PORTIONS OF OUR CWA FRI-SAT. HOWEVER,  
LINGERING LOW LEVEL MOISTURE COMBINED WITH DAYTIME HEATING WILL  
STILL ALLOW FOR THUNDERSTORMS TO DEVELOP MAINLY ALONG HIGHER TERRAIN  
THROUGH THE WEEKEND. BY SUN-MON, MODELS ARE NOW SHIFTING THE HIGH  
PRESSURE BACK ACROSS THE SOUTHWEST AND OVER ARIZONA. THIS WESTWARD  
PROPAGATION WILL INCREASE TEMPS AND CONTINUE TO KEEP THUNDERSTORMS  
CHANCES MAINLY FOCUSED OVER THE HIGHER TERRAIN THROUGH TUE. MAIN  
THREATS WITH ANY THUNDERSTORM DEVELOPMENT WILL BE LOCALIZED  
FLOODING, SMALL HAIL, AND STRONG TO SEVERE OUTFLOWS CAPABLE OF  
PRODUCING DAMAGING WINDS AND BLOWING DUST.  
 
BESIDES STORM CHANCES, EXPECT LIGHT WINDS LESS THAN 10-15 MPH,  
TEMPERATURES TO INCREASE A DEGREE OR TWO EACH DAY AND PARTLY SUNNY  
TO PARTLY CLOUDY SKIES.  

 
   
AVIATION...FOR MCCARRAN
 
OUTSIDE OF CONVECTIVE INFLUENCE, LIGHT,  
VARIABLE WINDS BELOW 10 KNOTS WILL CONTINUE ACROSS THE TERMINAL  
THROUGH THE AFTERNOON, FAVORING AN EASTERLY DIRECTION. PROBABILITY  
OF OUTFLOW AFFECTING THE TERMINAL THIS EVENING IS LOW. CIGS SHOULD  
REMAIN ABOVE 10K FEET.  
 
FOR THE REST OF SOUTHERN NEVADA, NORTHWEST ARIZONA AND SOUTHEAST  
CALIFORNIA...SCATTERED TO ISOLATED THUNDERSTORMS ACROSS THE REGION  
THROUGH THE REMAINDER OF THE AFTEROON WITH STORMS LIKELY TO PERSIST  
THROUGH THE NIGHT ALONG AND SOUTH OF INTERSTATE 40 THROUGH SOUTHERN  
CALIFORNIA AND SOUTHWEST ARIZONA. OUTSIDE OF THUNDERSTORM  
INFLUENCES, WINDS WILL FOLLOW DIURNAL TRENDS WITH SPEEDS OF 5-15  
KNOTS. CIGS AT OR ABOVE 10K FEET IN GENERAL BUT CIGS MAY DROP TO 5-7  
K FEET IN SHOWER AND STORMS.  

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

 
 

 
 
SHORT TERM/AVIATION...SALMEN  
LONG TERM.............KRYSTON  
 
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:  
 
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER  
 
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