870  
FXUS65 KVEF 202153  
AFDVEF  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LAS VEGAS NV  
253 PM PDT FRI JUL 20 2018  
   
SYNOPSIS
 
MOIST AND UNSTABLE AIR WILL REMAIN OVER THE REGION  
THROUGH THE END OF THE WEEK PROVIDING FUEL FOR AFTERNOON AND EVENING  
THUNDERSTORMS...ESPECIALLY OVER THE MOUNTAINS. NEXT WEEK, A HEATWAVE  
DEVELOPS WITH VERY HOT TEMPERATURES EXPECTED TUESDAY THROUGH  
THURSDAY ALONG WITH LOWERING THUNDERSTORM CHANCES.  

 
 
   
SHORT TERM
 
TONIGHT THROUGH SUNDAY.  
 
A MOIST AND UNSTABLE AIRMASS REMAINS IN PLACE OVER THE AREA TODAY.  
DIFFLUENT FLOW OVER THE SIERRA AND INYO COUNTY MOUNTAINS HAS  
INITIATED THUNDERSTORMS FAIRLY EARLY AND SHOULD ALLOW SCATTERED  
CONVECTION TO CONTINUE OVER THE SAME AREAS THROUGHOUT THE  
AFTERNOON/EARLY EVENING; LOCALIZED FLASH FLOODING WILL BE THE  
CONCERN FOR THE SIERRA. ELSEWHERE, CONVECTION HAS BEEN INCREASING  
OVER THE HIGHER TERRAIN. HIGHEST CAPE (1000-1500 J/KG) WILL BE  
FOCUSED ACROSS SOUTHERN INYO, SAN BERNARDINO, CLARK, AND MOHAVE  
COUNTIES; STRONGEST STORMS WILL BE FAVORED IN THESE AREAS. LARGE  
DCAPE VALUES WILL OVERLAP AREAS OF HIGH INSTABILITY. THUS,  
THUNDERSTORMS THAT DEVELOP WILL POSE A MICROBURST THREAT (VERY  
STRONG, SUDDEN WINDS) ALONG WITH AN ISOLATED FLOODING. GENERALLY,  
STORM MOTION WILL BE SOUTHERLY AROUND 5-10 MPH. THUNDERSTORM  
ACTIVITY SHOULD DIMINISH AFTER SUNSET.  
 
ON SATURDAY THE ATTENTION SHIFTS TO A DISTURBANCE/MCV RIDING ALONG  
THE WESTERN PERIPHERY OF AN EASTWARD MOVING RIDGE. MODEL GUIDANCE  
HAS BEEN FAIRLY CONSISTENT WITH THIS FEATURE FOR THE LAST COUPLE OF  
RUNS AND BRINGS IT INTO THE FORECAST AREA BY SATURDAY MORNING. WITH  
THIS IMPULSE PROGGED TO ADVANCE NORTHWARD AND COMBINE WITH DIURNALLY  
DRIVEN CONVECTION, POPS AND SKY WERE INCREASED ACROSS EASTERN  
SANBERN, SOUTHERN MOHAVE, CLARK, AND LINCOLN COUNTIES. TEMPERATURES  
WERE LOWERED SLIGHTLY TO ACCOUNT FOR ADDED CLOUD COVER ON SATURDAY.  
 
BY SUNDAY, THE DISTURBANCE (WHAT'S LEFT OF IT) SHOULD TRACK  
NORTHEASTWARD INTO UTAH AROUND THE RIDGE. MODERATE MOISTURE WILL  
REMAIN IN PLACE AND ALLOW FOR DIURNALLY DRIVEN CONVECTION OVER THE  
HIGHER TERRAIN. TEMPERATURES WILL BE WARMER SUNDAY COMPARED TO  
SATURDAY AS CLOUD COVER WILL BE LESS AND RIDGING BEGINS TO  
RETROGRADE BACK OVER THE SOUTHWEST. GENERALLY, TEMPERATURES WILL BE  
NEAR NORMAL THROUGH THE WEEKEND.  
   
LONG TERM
 
MONDAY THROUGH THURSDAY  
 
STRONG HIGH CENTER PROGGED TO SHIFT WESTWARD NEXT WEEK WITH  
TEMPERATURES EXPECTED TO PEAK TUESDAY-THURSDAY. LATE COLLABORATION  
WITH OFFICES THAT COVER THE DESERTS OF SOUTHERN CA IT WAS AGREED  
UPON TO ISSUE AN EXCESSIVE HEAT WARNING EARLY TO HELP AGENCIES GET  
AN EARLY START ON PREPARATIONS. CONFIDENCE MODERATE TO HIGH FOR  
THIS EVENT THAT FAR OUT SO MY SOUTHERN NEVADA AND NORTHWEST  
ARIZONA ZONES WERE UPGRADED TO A WARNING AS WELL. FOR THE SPRING  
MTNS AND SHEEP RANGE, A HEAT ADVISORY WAS ISSUED.  

 
 
   
AVIATION...FOR MCCARRAN
 
THUNDERSTORMS MOVING TO THE NORTH  
AROUND 10 MPH OVER THE MOUNTAINS SOUTH OF LAS VEGAS WILL LIKELY MOVE  
NEAR OR OVER THE TERMINAL DURING THE LATE AFTERNOON...PRODUCING  
GUSTY AND ERRATIC WINDS FOR THE TERMINAL AREA. INFLUENCES FROM  
THUNDERSTORMS WILL DIMINISH WITH SUNSET THIS EVENING AND MORE  
TRANQUIL CONDITIONS ARE EXPECTED OVERNIGHT THROUGH EARLY SATURDAY  
MORNING. SHOWERS OR THUNDERSTORMS WILL BE POSSIBLE NEAR THE LAS  
VEGAS VALLEY AGAIN BY SATURDAY AFTERNOON.  
 
FOR THE REST OF SOUTHERN NEVADA, NORTHWEST ARIZONA AND SOUTHEAST  
CALIFORNIA...THUNDERSTORMS OVER THE MOUNTAINS AROUND THE REGION WILL  
MOVE TO THE NORTH AROUND 10-15 KNOTS AND EXPAND IN COVERAGE THROUGH  
LATE AFTERNOON INTO EARLY EVENING. STORMS SHOULD LARGELY DISSIPATE  
AROUND SUNSET AND FAIRLY TRANQUIL CONDITIONS WILL REMAIN OVERNIGHT  
WITH REMNANT CLOUD BASES ABOVE 12 KFT MSL. ISOLATED TO SCATTERED  
THUNDERSTORMS CAN BE EXPECTED BY SATURDAY AFTERNOON AROUND THE  
REGION.  

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

 
 

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