AREA FORECAST DISCUSSION

 
 FXUS65 KVEF 140350
 AFDVEF
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE LAS VEGAS NV
 750 PM PST MON FEB 13 2012
 
 .SYNOPSIS...A WINTER STORM WILL IMPACT THE AREA THROUGH TUESDAY WITH 
 GUSTY WINDS ACROSS THE MOJAVE DESERT AND RAIN AND SNOW OVER THE 
 SOUTHERN GREAT BASIN. RAIN AND SNOW WILL BECOME MORE WIDESPREAD 
 TONIGHT THROUGH TUESDAY AS THE STORM MOVES INTO SOUTHERN NEVADA WITH 
 MODERATE TO HEAVY SNOWFALL POSSIBLE OVER THE HIGHER TERRAIN OF 
 SOUTHERN NEVADA AND FAR NORTHWEST ARIZONA. ANOTHER STORM IS FORECAST 
 TO MOVE INTO THE AREA BY MID WEEK BRINGING THE POTENTIAL FOR MORE 
 RAIN AND SNOW. 
 &&
 
 .UPDATE...WINDS HAD SUBSIDED EARLY THIS EVENING...WITH GUSTS LESS 
 THAN 40 MPH IN ALL THE POPULATED AREAS. THEREFORE...CANCELLED THE 
 HIGH WIND WARNING...WIND ADVISORY...AND LAKE WIND ADVISORY EARLY. 
 STILL A LOT OF UNCERTAINTY ABOUT THE EVOLUTION OF THE PRESUMED SNOW 
 BAND ON THE BACK SIDE OF THE LOW. CURRENT WINTER WARNINGS AND 
 ADVISORIES LOOK REASONABLE...SO LEFT THEM INTACT AT THIS TIME.
 &&
 
 .AVIATION...MCCARRAN...ANOTHER ROUND OF PRECIP WILL BE POSSIBLE 
 BETWEEN 8 AND 14Z THIS MORNING AS THE CENTER OF A LOW PRESSURE 
 SYSTEM PASSES OVER THE AREA...WITH CIGS DROPPING BACK DOWN TO 5-6KFT 
 AGL. CONDITIONS WILL BEGIN TO IMPROVE BY MID MORNING WITH THE LOW TO 
 THE EAST AND RIDGING BEGINS TO BRIEFLY BUILD BACK IN. THE NEXT ROUND 
 OF WEATHER IS EXPECTED LATE WEDNESDAY AFTERNOON THROUGH WEDNESDAY 
 NIGHT.
 
 FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST 
 CALIFORNIA...UPPER LOW OVER CENTRAL CALIFORNIA WILL TRACK EAST 
 ACROSS SOUTHERN NEVADA TONIGHT BEFORE EXITING EAST ACROSS ARIZONA 
 TUESDAY AFTERNOON. STRONG SURFACE WINDS WILL CONTINUE ACROSS THE 
 MOJAVE DESERT THIS EVENING...WHILE OCCASIONAL MODERATE TO SEVERE 
 MECHANICAL TURBULENCE FROM MTN WAVES WILL CONTINUE AS WELL. CIGS 
 WILL BE BLO 2 KFT IN -SHSN ACROSS CENTRAL NYE AND LINCOLN COUNTIES. 
 ACRS ERN CLARK AND MOHAVE COUNTY...WELL DEVELOPED BAND OF SHOWERS 
 AND ISOLATED THUNDERSTORMS WITH CIGS DOWN TO 5 KFT. HIR TRRN 
 OBSCURED.
 &&
 
 .PREV DISCUSSION...
 300 PM PST MON FEB 13 2012
 
 .SHORT TERM...UPPER LOW CURRENTLY OVER CENTRAL CALIFORNIA CONTINUES 
 TO TRACK SOUTH AND EAST THIS AFTERNOON. PRECIPITATION HAS ENDED OVER 
 MUCH OF INYO COUNTY...BUT HAS INCREASED IN INTENSITY AND COVERAGE 
 OVER LINCOLN AND CENTRAL NYE COUNTIES IN THE FAVORED UPPER DIFFLUENT 
 AREA. DRY SLOT WORKING INTO THE MOJAVE DESERT...BUT SHOWERS ARE 
 STARTING TO ENHANCE ON THE SOUTHERN FRINGE OF THE DRY SLOT OVER 
 CLARK COUNTY AND SOUTHERN LINCOLN COUNTIES. THESE SHOWERS ARE 
 EXPECTED TO CONTINUE AND INCREASE LATE THIS AFTERNOON AND EVENTUALLY 
 PUSH EAST AS THE LOW MOVES CLOSER AND EVENTUALLY WORK EAST INTO 
 MOHAVE COUNTY THIS EVENING. THIS BAND OF SHOWERS IS SHOWN TO ENHANCE 
 OVER NORTHERN MOHAVE COUNTY AND DECENT RAINFALL/HIGH ELEVATION 
 SNOWFALL AMOUNTS ARE POSSIBLE. STRONG WINDS HAVE DEVELOPED OVER MUCH 
 OF THE SOUTHERN PORTIONS OF THE AREA WITH THE STRONGEST WINDS OVER 
 WESTERN SAN BERNARDINO COUNTY. ONE RAWS SITE DID REPORT A GUST OF 74 
 MPH EARLIER AND THERE WAS A REPORT OF A POWER POLE BLOWN DOWN IN 
 YERMO. DID UPGRADE THE WIND ADVISORY OVER WESTERN SAN BERNARDINO 
 COUNTY TO A WARNING AS THESE STRONG WINDS ARE EXPECTED TO CONTINUE 
 FOR THE NEXT FEW HOURS. AS THE LOW APPROACHES THE AREA SNOW LEVELS 
 WILL DROP RAPIDLY AND ARE EXPECTED TO LOWER TO NEAR 3000 FEET BY 
 MORNING. MOST OF THE PRECIPITATION FOR SOUTHERN NEVADA WILL BE OVER 
 BY THE TIME THE COLDER AIR ARRIVES...BUT SHOWERS UNDER THE LOW 
 ITSELF AND SOME WRAP AROUND BEHIND THE LOW MAY BRING A FEW SNOW 
 FLURRIES TO THE FOOTHILLS EARLY TUESDAY MORNING. CURRENT SNOW 
 ADVISORIES AND WARNINGS LOOK GOOD AND NO CHANGES TO THOSE PRODUCTS 
 NEEDED. MUCH COLDER DAY EXPECTED TUESDAY AS H7 TEMPERATURES FALL TO 
 AROUND -10C WITH NORTHERLY FLOW ALL DAY. 
 
 ANOTHER LOW IS EXPECTED TO DROP SOUTH THROUGH NEVADA EARLY WEDNESDAY 
 AND INTO SOUTHERN NEVADA BY WEDNESDAY AFTERNOON. THIS WILL BRING 
 ADDITIONAL COOLER AIR ALONG WITH SHOWERS TO THE AREA. LOW SNOW 
 LEVELS ARE ALSO EXPECTED WITH THIS SYSTEM...BUT NO WINTER PRODUCTS 
 WILL BE ISSUED AT THIS TIME. 
 
 .LONG TERM...FRIDAY THROUGH MONDAY...MODELS IN GOOD AGREEMENT EARLY 
 ON IN THE EXTENDED THEN CONSIDERABLE DIFFERENCES STILL EXIST FOR THE 
 SUNDAY THROUGH MONDAY TIMEFRAME. ON FRIDAY...MODEL SHOW RIDGE AXIS 
 ALONG THE WEST COAST WITH THE GREAT BASIN UNDER A DRY NORTHWEST 
 FLOW. PROBABLY CONTINUE TO SEE SOME NORTH BREEZES DOWN THE COLORADO 
 RIVER VALLEY THROUGH FRIDAY. RIDGE AXIS SHIFTS EAST ACROSS THE GREAT 
 BASIN SATURDAY AS DIFFERENCES START BECOMING APPARENT WITH PLACEMENT 
 AND TIMING OF TROUGH ENTERING THE PACIFIC NORTHWEST. ECMWF THE 
 WEAKEST AND FASTEST MOVING A SHORTWAVE THROUGH SATURDAY 
 NIGHT...WHILE REMAINDER OF MEDIUM RANGE MODELS SLOWER AND DEPICT A 
 DEEPER TROUGH COMING ACROSS THE GREAT BASIN SUNDAY. TROUGH CONTINUES 
 EAST INTO THE FOUR CORNERS AREA MONDAY WITH THE POTENTIAL OF 
 INSTABILITY SHOWERS LINGERING ACROSS THE EASTERN HALF OF THE AREA AS 
 ADDITIONAL ENERGY DROPS IN FROM THE NORTH. BOTTOM LINE...LITTLE 
 CHANGE WAS DONE TO EXISTING GRIDS KEEPING A BROAD BRUSH APPROACH 
 WITH SLIGHT CHANCE POPS IN THE MOUNTAINS AND DRY IN THE VALLEYS. 
 LETS HOPE FOR BETTER MODEL CONSENSUS WITH TONIGHTS RUNS.
 
 .AVIATION...MCCARRAN...BAND OF LIGHT SHOWERS OVER CLARK COUNTY AHEAD 
 OF A LOW PRESSURE SYSTEM WILL PIVOT EAST ACROSS THE COLORADO RIVER 
 AND INTO MOHAVE COUNTY THIS EVENING. CIGS WILL LOWER TO 5KFT AS 
 SHOWERS PASS OVER LOCAL TERMINALS. SOUTHWEST WINDS WILL CONTINUE 
 AROUND 30 KTS THROUGH THIS EVENING BEFORE SUBSIDE QUICKLY AS UPPER 
 LOW PASS OVER SOUTHERN NEVADA. OCCASIONAL MODERATE TO SEVERE 
 MECHANICAL TURBULENCE FROM MTN WAVES WILL CONTINUE THROUGH THIS 
 EVENING AS WELL. THE VALLEY WILL LIKELY SEE A BREAK IN THE SHOWERS 
 LATE THIS EVENING BEFORE MORE RETURN EARLY TUESDAY THIS TIME COMING 
 IN FROM THE NORTH ON BACKSIDE OF UPPER LOW EXITING EAST ACROSS 
 NORTHWEST ARIZONA. CIGS WILL START TO SCATTER OUT TUESDAY 
 AFTERNOON. NO SIGNIFICANT WINDS EXPECTED AFTER THIS EVENING. 
 
 FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST 
 CALIFORNIA...UPPER LOW OVER CENTRAL CALIFORNIA WILL TRACK EAST 
 ACROSS SOUTHERN NEVADA TONIGHT BEFORE EXITING EAST ACROSS ARIZONA 
 TUESDAY AFTERNOON. STRONG SURFACE WINDS WILL CONTINUE ACROSS THE 
 MOJAVE DESERT THIS EVENING...WHILE OCCASIONAL MODERATE TO SEVERE 
 MECHANICAL TURBULENCE FROM MTN WAVES WILL CONTINUE AS WELL. CIGS 
 WILL BE BLO 2 KFT IN -SHSN ACROSS CENTRAL NYE AND LINCOLN COUNTIES. 
 IN THE LOWER DESERTS...CIGS DOWN TO 5 KFT IN -SHRA. HIR TRRN 
 OBSCURED. 
 &&
 
 .VEF WATCHES/WARNINGS/ADVISORIES...
 NV...WINTER WEATHER ADVISORY UNTIL 10 AM PST TUESDAY FOR NVZ018-019.
      WINTER STORM WARNING UNTIL 6 AM PST TUESDAY FOR NVZ014.
      WINTER STORM WARNING UNTIL 10 AM PST TUESDAY FOR NVZ015. 
 AZ...WINTER WEATHER ADVISORY UNTIL 1 PM MST TUESDAY FOR AZZ001.
 CA...NONE.
 &&
 
 

 
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