Area Forecast Discussion
Issued by NWS Las Vegas, NV

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000
FXUS65 KVEF 120554 AAA
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
955 PM PST THU FEB 11 2016

.SYNOPSIS...WARM AND DRY CONDITIONS WILL CONTINUE ACROSS THE REGION
THROUGH EARLY NEXT WEEK. BREEZY CONDITIONS WILL OCCUR ALONG THE
LOWER COLORADO VALLEY, ESPECIALLY ON SUNDAY AND MONDAY. THE NEXT
CHANCE FOR PRECIPITATION COMES LATE NEXT WEEK AS A STORM SYSTEM
MOVES THROUGH THE AREA.
&&

.UPDATE...QUIET EVENING ACROSS THE REGION AND NO UPDATES PLANNED.
&&

.DISCUSSION...

UPPER-LEVEL RIDGE REMAINS ESTABLISHED ACROSS THE WEST TODAY, BUT WV
IMAGERY SHOWS SEVERAL VORT MAXIMA IMPINGING UPON IT IN THE NORTHEAST
PACIFIC AND ADJACENT PORTIONS OF CANADA AND THE NORTHWEST US. ASIDE
FROM SCATTERED HIGH CLOUDS, NO IMPACTS ARE BEING FELT IN OUR AREA AS
TEMPERATURES AGAIN REACH 10-15 DEGREES ABOVE NORMAL VALUES. EXPECT
MORE OF THE SAME TOMORROW AS THE RIDGE BEGINS TO SLOWLY BREAK DOWN.
PERSISTENCE FORECAST FOR TEMPS TONIGHT AND TOMORROW.

POTENT SHORTWAVE TROUGH WILL REACH THE PACIFIC NORTHWEST COAST 00Z-
06Z SATURDAY WHICH WILL DAMPEN THE RIDGE SUBSTANTIALLY THIS WEEKEND.
SOUTHERN PORTION OF THE TROUGH WILL MOVE THROUGH THE AREA 00Z-12Z
SUNDAY, BUT THE RIDGE WILL HAVE EFFECTIVELY WEAKENED IT WELL BEFORE
IT REACHES OUR AREA. TROUGH PASSAGE WILL BE DRY, AND ONLY MINOR
COOLING WILL OCCUR ON SUNDAY (PERHAPS 2-4 DEGREES). NORTH WINDS WILL
KICK UP IN EASTERN PORTIONS OF THE AREA SUNDAY AND MONDAY,
ESPECIALLY IN THE COLORADO RIVER VALLEY. SO FAR, WINDS LOOK BELOW
ADVISORY CRITERIA, BUT THIS WILL CONTINUE TO BE MONITORED.

RIDGE WILL BUILD RIGHT BACK EARLY NEXT WEEK...QUICKLY BRINGING
SOMEWHAT WARMER TEMPS AND RETAINING DRY CONDITIONS. BREEZY NORTH
WINDS WILL CONTINUE IN THE COLORADO RIVER VALLEY EARLY NEXT WEEK
WITH A SLOW DECREASING TREND FROM MONDAY TO TUESDAY. MCCARRAN SHOULD
HAVE NO PROBLEM REACHING TEN OR MORE STRAIGHT DAYS OF 70+ DEGREE
HIGHS, AS MENTIONED IN THE PREVIOUS DISCUSSION.

AS A CUTOFF LOW DEVELOPS IN THE SUBTROPICAL EAST PACIFIC (A LAST
REMNANT OF THE SYSTEM MOVING THROUGH THIS WEEKEND), A STRONG LARGE-
SCALE TROUGH WILL AMPLIFY AS IT PASSES TO THE NORTH. MODELS CONTINUE
TO STRUGGLE WITH HOW THIS SYSTEM EVOLVES AS IT MOVES THROUGH THE
WEST, THOUGH THERE IS MUCH BETTER AGREEMENT TODAY THAN WHAT HAS BEEN
OBSERVED SO FAR. NEVERTHELESS, TIMING/PHASE ERRORS AND RUN-TO-RUN
CONSISTENCY PROBLEMS CONTINUE AMONGST THE MODELS. FOR EXAMPLE, 12Z
GFS IS WEAKER AND FASTER WITH THE SYSTEM, KEEPING MOST PRECIP OUT OF
OUR CWA ASIDE FROM THE SOUTHERN SIERRA. 18Z GFS IS A LITTLE DEEPER
WITH THE SYSTEM, BRINGING PRECIP TO MUCH OF THE AREA (ESPECIALLY
NORTH OF I-40). 12Z EURO IS SOMEWHERE IN THE MIDDLE, THOUGH THE
ORIENTATION OF THE TROUGH IS A BIT MORE FAVORABLE FOR BRINGING
CONSIDERABLE PRECIP TO THE SOUTHERN SIERRA WHILE ALSO ENHANCING
DOWNSTREAM SHADOWING (KEEPING MUCH OF THE REST OF THE CWA DRY AS THE
TROUGH PASSES).

WITH THE OVERALL DRIER APPEARANCE TO THE TROUGH IN THE PAST FEW
SIMULATIONS...ESPECIALLY FOR SOUTHERN PORTIONS OF THE AREA...REDUCED
INHERITED POPS A TAD FOR WEDNESDAY AND THURSDAY, ESPECIALLY GIVEN
THE CONTINUED UNCERTAINTY IN TIMING. BEST CHANCES REMAIN IN THE
SOUTHERN SIERRA AND SOUTHERN GREAT BASIN. TOO EARLY TO GET SPECIFIC
REGARDING QPF AND SNOW AMOUNTS...BUT THERE IS SOME POTENTIAL FOR
DECENT ACCUMULATIONS IN THE SOUTHERN SIERRA. SYSTEM WILL BE WARM, SO
SNOW LEVELS WILL BE QUITE HIGH, ESPECIALLY EARLY ON IN THE EVENT.
WILL NEED TO SEE MORE CONSENSUS WITH THIS SYSTEM BEFORE GETTING MORE
DETAILED THAN THAT.
&&

.AVIATION...FOR MCCARRAN...LIGHT WINDS DRIVEN BY DIURNAL PROCESSES
WILL BE IN CONTROL THROUGH THE END OF THE WEEK. WINDS WILL REMAIN
AOB 6 KTS THROUGH FRIDAY NIGHT.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...KEED AND KIFP WILL CONTINUE TO SEE SOMEWHAT STRONGER
NORTHERLY WINDS DURING THE DAY TOMORROW BUT SHOULD BE AOB 10 KTS
DURING THE OVERNIGHT HOURS. DIURNALLY DRIVEN WINDS WILL CONTINUE AT
THE REMAINING TERMINALS.
&&

.SPOTTER INFORMATION STATEMENT...SPOTTER ACTIVATION IS NOT EXPECTED.
PLEASE REPORT ANY SIGNIFICANT WEATHER ACCORDING TO STANDARD OPERATING
PROCEDURES.
&&

$$

SHAFER

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