939  
FXUS65 KVEF 150921  
AFDVEF  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LAS VEGAS NV  
221 AM PDT SUN SEP 15 2019  
   
SYNOPSIS
 
TODAY WILL BRING ONE MORE DAY OF ABOVE NORMAL  
TEMPERATURES BEFORE A LOW PRESSURE SYSTEM DROPPING DOWN FROM THE  
PACIFIC NORTHWEST MOVES ACROSS THE SOUTHERN SIERRA AND GREAT BASIN  
ON MONDAY BRINGING VERY WINDY CONDITIONS AND SIGNIFICANTLY COOLER  
TEMPERATURES. ANOTHER WEATHER SYSTEM WILL FOLLOW A SIMILAR TRACK  
AND BRING MORE WIND TO THE REGION WEDNESDAY THROUGH FRIDAY.  

 
   
DISCUSSION
 
TODAY THROUGH NEXT SUNDAY.  
 
ABOVE-AVERAGE TEMPERATURES CONTINUE TODAY, THOUGH CLOUD COVER AND  
WIND SPEEDS ARE EXPECTED TO PICK UP THIS EVENING. THE ZONAL FLOW  
THAT HAS BEEN BRINGING HOT, BUT PLEASANT, CONDITIONS TO OUR AREA  
WILL BEGIN TO BREAK DOWN TODAY AS WE PREPARE FOR AN INCOMING DIGGING  
TROUGH FROM THE PACIFIC NORTHWEST.  
 
INITIALLY, IMPACTS FROM THIS INCOMING WEATHER SYSTEM INCLUDE A  
WIDESPREAD INCREASE IN CLOUD COVER, AN INCREASE IN PRECIPITATION  
CHANCES FOR MOHAVE COUNTY, A WIDESPREAD GRADUAL UP-TICK IN WIND  
SPEEDS THROUGH THE AFTERNOON AND EVENING, AND AN EVENTUAL STARK DROP  
IN TEMPERATURES. A SOUTHERLY FLOW WILL SET UP AS THE TROUGH  
APPROACHES, AND WITH THIS FLOW WILL BE AN ASSOCIATED MILD MOISTURE  
FLUX INTO MOHAVE COUNTY. THIS MOISTURE WILL BRING THE CHANCE OF  
ISOLATED SHOWERS AND THUNDERSTORMS INTO NORTHWESTERN ARIZONA THIS  
AFTERNOON AS WELL AS MONDAY AFTERNOON. WITH REGARD TO WINDS, WE WILL  
BEGIN TO SEE IMPACTS ALONG THE EASTERN SIERRA SLOPES AND POSSIBLY  
DOWN THE OWENS VALLEY SUNDAY EVENING AND THROUGH THE OVERNIGHT  
HOURS. THOUGH, AS THESE INCREASED WIND SPEEDS SPREAD NORTH AND EAST  
TO ENCOMPASS MUCH OF THE SOUTHERN GREAT BASIN, SPEEDS LOOK TO PEAK  
MONDAY AFTERNOON AND EVENING WITH WIDESPREAD GUSTS 40-45 MPH. DUE TO  
THE POSSIBLE DOWNSLOPE WIND EVENT IN THE SIERRA, WIND GUSTS IN  
EXCESS OF 60 MPH ARE POSSIBLE MONDAY. AS A RESULT OF THESE FORECAST  
SPEEDS, WE HAVE ISSUED A HIGH WIND WATCH FOR THE EASTERN SIERRA  
SLOPES AND OWENS VALLEY ON MONDAY. IMPACTS TO THE OWENS VALLEY ARE  
WITH LOW CONFIDENCE AT THIS TIME. RAP FORECAST SOUNDINGS INDICATE  
THE PRESENCE OF A POSSIBLE INVERSION, THOUGH SHEAR LOOKS LIMITED -  
BOTH COMPONENTS NECESSARY FOR A HIGH CONFIDENCE FORECAST OF  
DOWNSLOPE WINDS REACHING THE VALLEY. WILL CONTINUE TO MONITOR  
POTENTIAL IMPACTS TO THE OWENS VALLEY AS WE GET CLOSER. THANKFULLY,  
AT THIS TIME, WIND SPEEDS LOOK TO DROP OFF LATE MONDAY NIGHT.  
 
AS THIS DIGGING TROUGH EXITS OUR AREA THROUGH TUESDAY, AN ASSOCIATED  
COLD FRONT WILL PLUMMET TEMPERATURES ACROSS THE REGION. FORECAST  
HIGHS WILL HAVE AN 8-12 DEGREE DROP BETWEEN SUNDAY AND TUESDAY WITH  
MANY AREAS SEEING BELOW-90 DEGREE AFTERNOON TEMPERATURES.  
 
ANOTHER TROUGH IS EXPECTED TO DIG FROM THE PACIFIC NW INTO OUR AREA  
THURSDAY AND INTO THE WEEKEND. IMPACTS ASSOCIATED WITH THIS INCLUDE  
PERSISTENT HIGH TEMPERATURES IN THE UPPER-80S TO LOWER-90S AND A  
RETURN OF BREEZY CONDITIONS.  

 
   
FIRE WEATHER
 
ABOVE-AVERAGE TEMPERATURES CONTINUE TODAY, THEN A  
STRONG LOW PRESSURE SYSTEM WILL BRING GUSTY WINDS TO INYO COUNTY  
SUNDAY AFTERNOON, SPREADING ACROSS MOST OF SOUTHERN NEVADA MONDAY. A  
RED FLAG WARNING IS IN EFFECT FOR INYO COUNTY CALIFORNIA ZONES FROM  
3 PM SUNDAY UNTIL 9 PM PDT MONDAY. HIGH DOWNSLOPE WINDS GUSTING TO  
AT LEAST 60 MPH WILL BE POSSIBLE ALONG THE EASTERN SIERRA SLOPES AND  
ADJACENT AREAS OF THE OWENS VALLEY EARLY MONDAY AFTERNOON THROUGH  
EARLY MONDAY EVENING. A RED FLAG WARNING IS IN EFFECT FOR THE  
SOUTHERN NEVADA ZONES FROM 11 AM MONDAY MORNING UNTIL 9 PM PDT  
MONDAY EVENING. A BELT OF STRONG SOUTHWEST WINDS GUSTING NEAR 40 MPH  
IS FORECAST FOR THE SOUTHERN GREAT BASIN. THESE STRONG WINDS WILL BE  
ACCOMPANIED BY MINIMUM RH VALUES IN THE SINGLE-DIGITS TO LOWER-TEENS.  

 
   
AVIATION...FOR MCCARRAN
 
EXPECT SOUTHERLY WINDS INCREASING TO 10  
TO 15 KNOTS THIS AFTERNOON, WITH GUSTS 20 TO 25 KNOTS POSSIBLE  
OVERNIGHT. SOUTHERLY WINDS WILL PEAK MONDAY, WITH GUSTS OF 30 TO 35  
KNOTS POSSIBLE. THERE WILL BE A CHANCE OF THUNDERSTORMS EACH DAY IN  
THE PEACH SPRINGS CORRIDOR, BUT NOT AT THE TERMINAL, WHERE NO  
OPERATIONALLY SIGNIFICANT CLOUDS ARE EXPECTED THROUGH THE PERIOD.  
 
FOR THE REST OF SOUTHERN NEVADA, NORTHWEST ARIZONA AND SOUTHEAST  
CALIFORNIA...SOUTHERLY WINDS GUSTING 15 TO 25 KNOTS ARE EXPECTED  
AREAWIDE TODAY, WITH CHANCES FOR THUNDERSTORMS LIMITED TO MOHAVE  
COUNTY. MONDAY WILL BE THE WINDIEST DAY FOR MOST AREAS, WITH  
SOUTHWEST WINDS GUSTING TO 20 TO 30 KNOTS SOUTHEAST OF INTERSTATE 15  
AND 30 TO 40 KNOTS NORTHWEST OF INTERSTATE 15. THERE WILL ALSO BE A  
RISK OF DOWNSLOPE WINDS ON THE EASTERN SLOPES OF THE SIERRA, WITH  
GUSTS OF 40 TO 50 KNOTS POSSIBLE. CHANCES FOR THUNDERSTORMS WILL BE  
OVER MOHAVE COUNTY AGAIN, WITH CHANCES POSSIBLY SPREADING INTO  
EASTERN CLARK AND LINCOLN COUNTIES AS WELL AS THE SIERRA AND NEARBY  
AREAS.  

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

 
 

 
 
DISCUSSION/FIRE WEATHER...VARIAN  
AVIATION..................MORGAN  
 
FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:  
 
HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER  
 
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