Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 270530 AAA
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
930 PM PST FRI DEC 26 2014

.SYNOPSIS...A COLD NORTHWEST FLOW WILL CONTINUE OVER THE AREA
THROUGH EARLY NEXT WEEK. DRY BUT COOL CONDITIONS CAN BE EXPECTED
ALTHOUGH A WEAK DISTURBANCE COULD BRING A FEW LIGHT SNOW SHOWERS TO
NORTHERN LINCOLN COUNTY MONDAY. SOME AREAS WILL DROP BELOW FREEZING
FOR THE FIRST TIME THIS SEASON TONIGHT OR SATURDAY NIGHT. ANOTHER
STORM SYSTEM WILL DROP INTO THE AREA BY THE MIDDLE OF NEXT WEEK
LEADING TO VERY COLD TEMPERATURES AND PERHAPS SOME SHOWERS WITH A
SLIGHT CHANCE OF LOW ELEVATION SNOW.
&&

.UPDATE...CLOUDS HAVE BEEN DISSIPATING OVER MUCH OF THIS AREA THIS
EVENING EXPECT FOR PORTIONS OF NORTHERN LINCOLN COUNTY WHERE SOME
LOW CLOUDS ARE HANGING ON. WINDS HAVE ALSO BEEN SLOWLY DIMINISHING
THIS EVENING AND THAT TREND IS EXPECTED TO CONTINUE OVERNIGHT. SOME
VERY COLD TEMPERATURES ARE IN STORE FOR PORTIONS OF THE AREA TONIGHT
AND THE CURRENT FREEZE AND HARD FREEZE WARNINGS LOOK GOOD. NO
UPDATES PLANNED.
&&

PREV DISCUSSION...
218 PM PST FRI DEC 26 2014

.SHORT TERM...TONIGHT THROUGH MONDAY NIGHT.

A STRONG NORTHERLY FLOW ALOFT IS OVER THE AREA THIS AFTERNOON AND
WILL PERSIST TONIGHT WHILE WEAKENING. SOME LOW CLOUDS MAINLY OVER
LINCOLN AND CENTRAL NYE COUNTY MAY PERSIST INTO THE EVENING BUT
SHOULD DECREASE BY MIDNIGHT. OTHERWISE...DECREASING WINDS SHOULD
ALLOW TEMPERATURES TO DROP TO THE COOLEST OF THE SEASON FOR SOME
AREAS. A WEAKER AND STILL DRY NORTHWEST FLOW IS EXPECTED SATURDAY
THROUGH SUNDAY. COOL TEMPERATURES WILL CONTINUE WITH ANOTHER COLD
NIGHT ON TAP SATURDAY NIGHT. THE FREEZE WARNING FOR MUCH OF SAN
BERNARDINO COUNTY STILL LOOKS GOOD FOR TONIGHT AND WITH LIGHTER
WINDS SATURDAY NIGHT THE FREEZE WARNING STILL LOOKS GOOD FOR THE
NEEDLES ZONE. AS FOR THE HARD FREEZE WARNING FOR SOUTHERN NYE AND
WESTERN CLARK COUNTIES AND THE NORTHWEST DESERTS OF ARIZONA IT LOOKS
JUST AS COLD TONIGHT AS SATURDAY NIGHT AND THE DURATION OF FREEZING
TEMPERATURES JUST ABOUT AS LONG. THEREFORE I ADJUSTED THE HARD
FREEZE WARNING TO INCLUDE TONIGHT AS WELL AS SATURDAY NIGHT.
A WEAK SHORTWAVE MOVING THROUGH THE NORTHWEST FLOW WILL CLIP
NORTHERN LINCOLN COUNTY WITH A SLIGHT CHANCE OF SNOW SHOWERS SUNDAY
NIGHT AND MONDAY BUT ANY PRECIPITATION THAT DOES FALL WILL BE VERY
LIGHT. A MAINLY DRY WEST TO NORTHWEST FLOW WILL BE OVER THE AREA
MONDAY NIGHT WITH THE NEXT UPPER TROUGH MOVING INTO NORTHERN NEVADA.

.LONG TERM...TUESDAY THROUGH FRIDAY.

AS WE GET READY TO SAY BON VOYAGE TO 2014 AND WELCOME IN 2015,
CONFIDENCE IN THE FORECAST IS EXCELLENT WITH RESPECT TO IT BEING
BRRRRRRR! BUT NOT AS MUCH WITH WHAT THE IMPACTS OF A END OF
2014/START OF 2015 STORM WILL BE. THE OPERATIONAL MODELS AND
ENSEMBLES HAVE BEEN REMARKABLY CONSISTENT ON BRINGING A STORM SYSTEM
IN OR NEAR SOUTHERN NEVADA AROUND NEW YEAR`S DAY FOR ABOUT A WEEK
NOW BUT HAVE STRUGGLED TO MAINTAIN ANY RUN TO RUN CONSISTENCY ON THE
TRACK AND TIMING OF THIS SYSTEM. MODEL RUNS HAVE A FAVORED SHOWING A
CLOSED LOW, HOWEVER, SOME RUNS HAVE TAKEN THE LOW TO OUR WEST. THIS
WOULD FAVOR A STORM WITH MORE MOISTURE GETTING ENTRAINED IN TO IT.
OTHER RUNS HAVE SHOWN THE STORM FURTHER EAST, WHICH WOULD FAVOR A
DRIER SYSTEM FOR OUR AREA.

BASED ON THE 12Z OPERATIONAL RUNS, WHICH WERE NOT IN BAD AGREEMENT,
AS WELL AS BLEND OF TRACKS/SOLUTIONS ON PREVIOUS RUNS, THE CURRENT
FORECAST LEANS TOWARD THE IDEA OF A CLOSED LOW DROPPING SOUTH ON
TUESDAY INTO CENTRAL NEVADA/EAST-CENTRAL CALIFORNIA. THIS WOULD
BRING THE POTENTIAL FOR SOME SHOWERS TO THE NORTHERN THIRD OF THE
CWFA - MAINLY FROM INYO COUNTY EAST TO LINCOLN COUNTY STARTING ON
TUESDAY AFTERNOON AND THEN SPREADING SOUTH INTO THE REST OF THE AREA
FOR TUESDAY NIGHT. CONFIDENCE IS A BIT HIGHER BASED ON A BLEND OF
STORM TRACKS FOR MORE MOISTURE AND/OR BETTER FORCING TO EXIST OVER
LINCOLN, MOHAVE AND NORTHEAST CLARK COUNTIES AND AS A RESULT THE
HIGHEST POPS WERE PLACED OVER THESE AREAS WITH LOWER POPS ELSEWHERE.
SIMILAR POPS HOLD INTO NEW YEAR`S EVE DAY WITH POPS DECREASING
SLIGHTLY IN THE WEST NEW YEAR`S EVE NIGHT AS THE LOW POTENTIALLY
STARTS TO PULL AWAY TO THE EAST. BY NEW YEAR`S DAY, THE BEST CHANCE
FOR ANY SHOWERS AT THIS POINT FAVORS LINCOLN COUNTY AS WELL AS AREAS
ALONG AND EAST OF THE COLORADO RIVER.

THE MAIN IMPACT FROM THIS SYSTEM WILL BE THE INFLUX OF CHILLY AIR
WITH PROGGED 700 MB TEMPS OFF THE GFS AND ECMWF BETWEEN -10C AND
-16C ACROSS THE AREA. REGARDLESS OF PRECIPITATION CHANCES, THE COLD
AIR LOOKS LOCKED IN WITH TEMPS ONLY GETTING COLDER AS THE SYSTEM
SWINGS THROUGH ON NEW YEAR`S EVE. THIS WILL MAKE FOR A RATHER CHILLY
NEW YEAR`S EVE FOR ANYONE OUT AND ABOUT THAT EVENING. IF YOU BUY THE
COLDER ECMWF SOUNDINGS, TEMPS COULD CHALLENGE THE RECORD LOW MAXIMUM
FOR NEW YEAR`S DAY IN LAS VEGAS OF 39 DEGREES SET IN 1979 AND TIED
IN 2011. NORTHWEST FLOW ALOFT IS EXPECTED TO LAST THROUGH FRIDAY,
WHICH WILL SUPPORT TEMPS REMAINING 6-12 DEGREES BELOW NORMAL. I
LEANED TOWARD A BLEND OF STATISTICAL GUIDANCE AS WELL AS FORECAST
SOUNDINGS OFF THE GFS AND ECMWF FOR TEMPS. THOSE WITH COLD SENSITIVE
INTERESTS SHOULD BE PREPARED FOR MULTIPLE NIGHTS OF SUBFREEZING
TEMPS IN LOWER DESERT VALLEYS WITH PROLONGED NIGHTS OF HARD FREEZES
IN COLDER SPOTS AWAY FROM URBAN/TOWN CENTERS AND THE COLORADO RIVER.

WITH SUFFICIENTLY COLD AIR IN PLACE, WE WILL NEED TO KEEP AN EYE ON
JUST HOW MOIST IT MANAGES TO GET AS WELL AS WHAT THE TRACK OF THE
SYSTEM ENDS UP BEING. IF THE LOW TRACKS OVER OR WEST OF THE AREA, A
GREATER CHANCE FOR SHOWERS WILL EXIST OVER MORE OF THE AREA. EVEN
WITH MEAGER MOISTURE, STRONG FORCING COULD BE ENOUGH TO GENERATE
SHOWERS, WHICH WOULD EASILY REACH MOST LOWER DESERT VALLEYS AS
PRECIPITATION IN THE FORM OF SNOW. IT IS FAR TOO EARLY TO SAY MUCH
MORE ON THIS, BUT WITH MANY TRAVELING TO VEGAS FOR NEW YEAR`S WE
ADVISE YOU TO KEEP IN TOUCH WITH THE LATEST FORECAST. IN THIS
PATTERN, SOME LOWER ELEVATIONS COULD EVEN HAVE THE POTENTIAL TO SEE
ACCUMULATING SNOW NEW YEAR`S EVE INTO NEW YEAR`S DAY WHICH WOULD
MAKE TRAVEL EXTREMELY DIFFICULT, ESPECIALLY IN THE PASSES.
&&

.AVIATION...FOR MCCARRAN...NORTH/NORTHWEST WINDS WILL GRADUALLY
DECREASE THROUGH TONIGHT AND WILL MAINLY BE UNDER 10 KTS. HOWEVER
THERE COULD BE GUSTS 15-20 KTS THROUGH ABOUT 02Z THIS EVENING. WINDS
WILL BECOME LIGHT NORTHEAST BY ABOUT 18Z SATURDAY MAINLY 4-8 KTS.
FEW-SCT CLOUDS AT ABOUT 8 KFT THROUGH EARLY THIS EVENING THEN CLEAR
SKIES WITH MAYBE SOME HIGH CLOUDS SATURDAY.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...NORTH/NORTHWEST WINDS WILL CONTINUE TONIGHT ACROSS THE
REGION WITH SPEEDS 5-15 KTS. MAINLY LIGHT AND VARIABLE WINDS
EXPECTED SATURDAY EXCEPT PERSISTING NORTH WINDS DOWN THE COLORADO
RIVER VALLEY AT 10-20 KTS. FEW-SCT CLOUDS 7-9 KFT THROUGH THIS
EVENING THEN GENERALLY CLEAR WITH A FEW HIGH CLOUDS AT TIMES THROUGH
SATURDAY.
&&

.CLIMATE...HERE ARE A FEW STATS TO WATCH IN THE COMING DAYS WITH
RESPECT TO FREEZING TEMPS AND `COLD` TEMPS IN LAS VEGAS. ALL DATA IS
FOR THE OFFICIAL CLIMATE STATION AT MCCARRAN INTERNATIONAL AIRPORT.

* GREATEST NUMBER OF CONSECUTIVE DAYS WITH LOWS ABOVE FREEZING...

  1. COUNTING TODAY - 379 DAYS - STARTED ON DECEMBER 13, 2013
  2. 378 DAYS - DECEMBER 8, 2011 - DECEMBER 19, 2012

* LATEST OCCURRENCE OF THE FIRST FREEZE OF THE SEASON...

  RECORD: ONGOING (HAS YET TO HIT 32 AT MCCARRAN)
  PREVIOUS RECORD: DECEMBER 20, 2012

* FEWEST NUMBER OF DAYS BELOW 40 IN DECEMBER...

  CURRENT RECORD: 5 DAYS IN 2010
  2014 SO FAR THROUGH TODAY: 1 DAY

* FEWEST NUMBER OF FREEZES IN DECEMBER...

  CURRENT RECORD: ONE DAY IN 1977 AND IN 2010
  2014 SO FAR THROUGH TODAY: 0 DAYS

* FEWEST NUMBER OF DAYS BELOW 40 DEGREES IN A CALENDAR YEAR...

  CURRENT RECORD: 28 DAYS IN 2010
  2014 TOTAL SO FAR THROUGH TODAY: 10 DAYS

* FEWEST NUMBER OF DAYS AT OR BELOW 32 DEGREES IN A CALENDAR YEAR...

  CURRENT RECORD: 2 DAYS IN 2005
  2014 TOTAL SO FAR THROUGH TODAY: 0 DAYS

  FYI...MEASURABLE SNOW FELL ON THE WEST SIDE OF LAS VEGAS ON
  JANUARY 7TH 2005 DESPITE NO FREEZES AT MCCARRAN IN JANUARY 2005.
&&

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME. HOWEVER...SPOTTERS
ARE ENCOURAGED TO REPORT ANY SIGNIFICANT WEATHER CONDITIONS
ACCORDING TO STANDARD OPERATING PROCEDURES.
&&

$$

UPDATE...GORELOW
SHORT TERM/AVIATION...HARRISON
LONG TERM/CLIMATE...STACHELSKI

FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:

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