Area Forecast Discussion
Issued by NWS Las Vegas, NV

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS65 KVEF 210405 AAA AFDVEF AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAS VEGAS NV 905 PM PDT SAT SEP 20 2014 .SYNOPSIS...A LOW PRESSURE SYSTEM CIRCULATING NEAR THE SOUTHERN CALIFORNIA COAST WILL PULL MOISTURE ACROSS SOUTHERN NEVADA AND NORTHWEST ARIZONA THROUGH SUNDAY LEADING TO SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS. THE SYSTEM WILL LIFT AWAY TO THE NORTHEAST BY LATE SUNDAY FOLLOWED BY DRY CONDITIONS AND ABOVE NORMAL TEMPERATURES THROUGH THE FIRST HALF OF NEXT WEEK. && .UPDATE...UPPER LOW OVER CENTRAL CALIFORNIA THIS EVENING PLACING MUCH OF THE AREA UNDER REGION OF DIFFLUENCE ALOFT. THERE HAVE BEEN THREE DISTINCT LINES OF THUNDERSTORMS AFFECTING THE AREA SINCE AFTERNOON. MOST INTENSE LINE AT THIS HOUR CONTINUES TO BE LINE RUNNING NEAR/ALONG HIGHWAY 93 FROM IN LINCOLN COUNTY SOUTH INTO NORTHEAST LAS VEGAS VALLEY. OTHER LINE OVER SOUTHWEST INYO COUNTY AND THE ONE FROM NEAR TONOPAH SOUTH TO DEATH VALLEY NATL PARK HAVE SHOWN SIGNS OF WEAKENING. WILL BE MONITORING SOME OUTFLOW BOUNDARIES AROUND LAS VEGAS FOR ANY DEVELOPMENT AS WELL. LINCOLN COUNTY WILL REMAIN UNDER THE GUN THE REST OF TONIGHT INTO SUNDAY WHILE DRIER/MORE STABLE AIR PRESENTLY OVER SAN BERNARDINO COUNTY GRADUALLY SPREADS NORTH. FORECAST LOOKS FINE THE REST OF TONIGHT/SUNDAY. NO UPDATE. && .AVIATION...FOR MCCARRAN...OUTFLOW BOUNDARIES WILL AFFECT THE LAS VEGAS VALLEY THROUGH 05Z-06Z THIS EVENING WITH NORTH-NORTHEAST WINDS ...GUSTING AROUND 25 KTS AT TIMES. BY LATE EVENING AND OVERNIGHT WINDS SHOULD RETURN TO THE TYPICAL SOUTH-SOUTHWEST AT LESS THAN 10 KTS. ISOLATED SHOWERS/THUNDERSTORMS COULD AFFECT VALLEY TERMINALS INTO LATE EVENING. STORM COVERAGE WILL BE MOST EXTENSIVE IN BEATTY...PEACH SPRINGS...AND MORMON MESA CORRIDORS. BKN-OVC CLOUDS WILL GENERALLY HAVE BASES 8-10 KFT BUT WILL LIKELY LOWER TO AROUND 6 KFT NEAR ANY SHOWERS AND THUNDERSTORMS. A CLEARING TREND WILL OCCUR SUNDAY. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...MOISTURE CONTINUES TO INCREASE OVER MUCH OF SOUTHERN NEVADA AND NORTHWEST ARIZONA WITH SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS EXPECTED THROUGH TONIGHT. LOWERING CLOUDS BASES WILL LEAD TO MARGINAL VFR CONDITIONS OVER SOUTH CENTRAL NEVADA AND NORTHWEST ARIZONA WITH MOUNTAIN OBSCUREMENT LIKELY. A CLEARING TREND WILL OCCUR FROM SOUTHWEST TO NORTHEAST SUNDAY. && .PREV DISCUSSION... 245 PM PDT SAT SEP 20 2014 .SHORT TERM /THROUGH MONDAY NIGHT/... THE UPPER LOW WE HAVE BEEN WATCHING THE LAST FEW DAYS OVER THE WESTERN CALIFORNIA COAST IS STARTING TO MOVE NORTHEAST AND WILL CONTROL OUR WEATHER THROUGH SUNDAY. THIS WILL PROVIDE SHOWER AND THUNDERSTORM CHANCES AS WELL AS COOLER TEMPERATURES. DRY CONDITIONS AND A WARMING TREND WILL COMMENCE MONDAY. MOISTURE CONTINUES TO INCREASE ACROSS OUR AREA...WRAPPING CYCLONICALLY AROUND THE UPPER LOW TO OUR WEST. SCATTERED SHOWERS AND THUNDERSTORMS HAVE BEEN AROUND THROUGHOUT THE DAY AND WILL INCREASE IN COVERAGE THROUGH THIS EVENING. AREA PW VALUES RANGING FROM 1 INCH IN OUR NORTHWEST TO 1.5 INCHES ALONG THE COLORADO RIVER NEAR NEEDLES ARE FORECAST BY EARLY EVENING...WHICH WOULD PROMOTE HEAVY RAIN. AREA AVERAGE RAIN AMOUNTS OF 0.25-0.50 INCHES WITH LOCALIZED AMOUNTS OVER 1 INCH WILL BE POSSIBLE. THE AVERAGE STORM MOTION WILL BE AROUND 20 MPH OR SO...WITH STORMS MOVING FROM SOUTHEAST TO NORTHWEST. THIS MOTION WOULD GENERALLY LIMIT THE AMOUNT OF TIME ANY ONE CELL IS OVER ONE PARTICULAR AREA. HOWEVER...THERE CAN BE SOME ISOLATED AREAS WHERE REDEVELOPMENT OR TRAINING CONVECTION FOR A SHORT PERIOD OF TIME MAY WARRANT THE ISSUANCE OF A FLASH FLOOD WARNING HERE AND THERE. WITH WIDESPREAD FLASH FLOODING NOT ANTICIPATED AT THIS TIME...WILL NOT ISSUE ANY WATCH PRODUCTS BUT TRENDS WILL BE MONITORED. THE STRONGEST STORMS MAY ALSO PRODUCE SOME GUSTY WINDS IN EXCESS OF 45 MPH AS WELL AS SOME HAIL. SO PLEASE KEEP ALERT OF CHANGING WEATHER CONDITIONS THIS AFTERNOON AND EVENING PARTICULARLY IF YOU HAVE OUTDOOR PLANS. THE LOW WILL CONTINUE A NORTHEAST TRACK ACROSS CALIFORNIA AND NEVADA TONIGHT AND SUNDAY. THE FOCUS FOR CONVECTION WILL SHIFT NORTH...WITH DRIER AIR WORKING INTO OUR CALIFORNIA AREAS LATE TONIGHT AND ESPECIALLY BY SUNDAY AFTERNOON. SO...SHOWER AND THUNDERSTORM CHANCES WILL BE MAINLY CONFINED TO SOUTHERN NEVADA AND NORTHWEST ARIZONA SUNDAY. THE LOW WILL EXIT THE REGION BY SUNDAY NIGHT WITH DRY AIR PUSHING ACROSS THE REST OF THE AREA OVERNIGHT...BRINGING AN END TO SHOWER AND STORM CHANCES. .LONG TERM...TUESDAY AND WEDNESDAY. HIGH PRESSURE EXPANDS OVER THE AREA IN RESPONSE TO A DEEPENING PACIFIC TROUGH OFF THE WEST COAST. OVERALL, DRY AND MOSTLY CLEAR CONDITIONS ALONG WITH LIGHT WINDS ARE EXPECTED. TEMPERATURES ARE FORECAST TO BE 4-8 DEGREES ABOVE NORMAL. WEDNESDAY THROUGH SATURDAY...CONTINUED TRENDING THE FORECAST WITH THE MORE CONSISTENT GFS DURING THIS PERIOD BUT DID NOT COMPLETELY RULE OUT THE ECMWF GIVEN ITS AGREEMENT WITH THE GFS REGARDING A CLOSED LOW MOVING OVER THE GREAT BASIN. THE GFS BRINGS A SHARP SHORTWAVE AROUND THE BASE OF A PACIFIC TROUGH AND INTO NORTHERN AND CENTRAL CALIFORNIA THURSDAY. THIS WOULD RESULT IN BREEZY TO LOCALLY WINDY CONDITIONS ACROSS THE AREA WITH POSSIBLE WEAK DOWNSLOPE FLOW OCCURRING ALONG THE EASTERN SIERRA SLOPES. THE GFS SOLUTION LIFTS THE SHORTWAVE QUICKLY TO THE NORTHEAST WITH THE MAIN TROUGH AXIS THEN PUSHING INTO CALIFORNIA AND NEVADA FRIDAY. IF THE GFS IS CORRECT, THERE COULD BE A PERIOD OF STRONG WINDS ACROSS PORTIONS OF THE AREA FRIDAY WITH WARM TEMPERATURES AGAIN OVER THE DESERTS BUT COOLING CONDITIONS OVER INYO COUNTY AND THE SOUTHERN GREAT BASIN. COOLER WEATHER WOULD THEN BE IN STORE FOR THE BEGINNING OF THE WEEKEND WITH TEMPERATURES POTENTIALLY WELL BELOW NORMAL FOR LATE SEPTEMBER. THE ECMWF IS MUCH WETTER THAN THE GFS ON SATURDAY DUE TO THE LOCATION OF THE LOW SO THE OFFICIAL FORECAST TAKES THIS INTO ACCOUNT WITH A SLIGHT CHANCE OF SHOWERS IN THE FAVORED REGIONS OF THE LOW WHICH INCLUDES PORTIONS OF THE SIERRA, THE NORTHERN CWA AND MOHAVE COUNTY. && .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. HOWEVER....SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES. && $$ UPDATE...PIERCE SHORT TERM/AVIATION...PADDOCK LONG TERM...SALMEN FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.