Area Forecast Discussion
Issued by NWS Las Vegas, NV

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
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
000
FXUS65 KVEF 040918
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
217 AM PDT WED MAY 4 2016

.SYNOPSIS...
AN AREA OF LOW PRESSURE OFF THE CALIFORNIA COAST WILL BRING
INCREASING SOUTH WINDS ALONG WITH ABOVE NORMAL TEMPERATURES TO THE
REGION TODAY. GUSTY WINDS ARE EXPECTED TO CONTINUE INTO
THURSDAY...BUT TEMPERATURES WILL START TO COOL. INCREASING CHANCES
OF VALLEY RAIN AND MOUNTAIN SNOW ARE EXPECTED THURSDAY THROUGH
SUNDAY ALONG WITH THE POSSIBILITY OF ISOLATED THUNDERSTORMS.
TEMPERATURES WILL BE WELL BELOW NORMAL FRIDAY THROUGH SUNDAY.
&&

.DISCUSSION...

STRONG RIDGE OF HIGH PRESSURE OVER THE ROCKY MOUNTAIN STATES WILL
SHIFT EAST TODAY AS A DEEP AREA OF LOW PRESSURE APPROACHES THE WEST
COAST. THIS WILL BRING INCREASING SOUTH WINDS TO THE AREA ALONG WITH
WHAT IS LIKELY THE WARMEST DAY OF THE YEAR SO FAR DUE TO INCREASE
MIXING. THE MODELS ARE HINTING AT A FEW SHOWERS MOVING INTO THE
SIERRA LATE THIS AFTERNOON...BUT MOST ARE EXPECTED TO REMAIN AT THE
HIGHER ELEVATIONS OF THE SOUTHERN SIERRA.

WIND FORECAST WITH THE APPROACHING SYSTEM IS TRICKY AS MOST GUIDANCE
IS SHOWING BORDERLINE ADVISORY CONDITIONS FOR THE SOUTHERN GREAT
BASIN, OWENS VALLEY, AND DEATH VALLEY TODAY AND FOR LINCOLN AND
MOHAVE COUNTIES ON THURSDAY. THE TIMING OF THE APPROACH IS OUT OF
PHASE WITH MAXIMUM DAYTIME HEATING TODAY, SO WHEN THE STRONGEST
MIDLEVEL SOUTHERLIES REACH THE WESTERN PORTIONS OF THE AREA (I.E.,
AFTER SUNSET TONIGHT), SUFFICIENT MIXING OF THESE WINDS TO THE
SURFACE WILL BE LACKING. NEVERTHELESS, HI-RES MODELS GENERATE
MARGINAL ADVISORY CONDITIONS IN ESMERALDA AND CENTRAL NYE COUNTIES
AS WELL AS OWENS VALLEY AND DEATH VALLEY THIS AFTERNOON AND EARLY
EVENING. AS SITES IN THESE LOCATIONS TEND TO MEASURE SOMEWHAT HIGHER
THAN FORECAST PROJECTIONS IN STRONG SOUTHERLY FLOW REGIMES...WENT
AHEAD AND ISSUED A WIND ADVISORY FOR THESE LOCATIONS THIS
AFTERNOON/EVENING.

THE CLOSED UPPER LOW WILL START TO PUSH INLAND THURSDAY AND EDGE
EASTWARD ACROSS SOUTHERN CALIFORNIA THURSDAY NIGHT. THURSDAY`S WIND
FORECAST IS A LITTLE MORE STRAIGHT FORWARD AS STRONG MIDLEVEL
SOUTHERLY JET REACHES EASTERN PORTIONS OF THE AREA DURING MAXIMUM
HEATING. AS SUCH, ISSUED A WIND ADVISORY FOR LINCOLN AND MOST OF
MOHAVE COUNTY THURSDAY AFTERNOON/EVENING WITH SOMEWHAT HIGHER
CONFIDENCE. FOR THE MOJAVE DESERT, NOT ENOUGH CONFIDENCE TO ISSUE
ADVISORIES EITHER DAY AS MODEL FORECASTS ARE GENERALLY BELOW
CRITERIA (OR TOO BRIEFLY ABOVE CRITERIA) AND THE MORE SOUTHERLY
DIRECTION OF THE WINDS IS NOTE SPECIALLY FAVORABLE FOR THESE AREAS
TO BLOW. FOR THE REST OF THE AREA...BREEZY SOUTHERLY WINDS REMAINING
BELOW ADVISORY CRITERIA ARE EXPECTED BOTH DAYS.

PRECIPITATION CHANCES SPREAD EAST AND ENCOMPASS THE ENTIRE FORECAST
AREA FRIDAY THROUGH SATURDAY AS THE UPPER LOW SPINS DIRECTLY
OVERHEAD. ON AND OFF SHOWERS ARE LIKELY, SIMILAR TO WHAT WE HAVE
EXPERIENCED WITH PREVIOUS SYSTEMS. SNOW LEVEL WILL DROP TO 6500-7000
FEET ACROSS THE REGION, WITH SOME VERY LIGHT SNOW ACCUMULATIONS ON
MOUNTAIN TOPS. THE SIERRA NEVADA WOULD STAND THE BEST ACCUMULATIONS,
WITH POSSIBLY GREATER THAN 12 INCHES FOR THE HIGHEST PEAKS DURING
THE THURSDAY THROUGH SATURDAY TIME PERIOD. DURING THAT SAME PERIOD,
VALLEY RAIN SHOULD RANGE FROM ROUGHLY 0.10 TO 0.30 INCHES, WITH
LOCALLY HIGHER AMOUNTS IN INYO AND MOHAVE COUNTIES. PLUS HIGHER
TOTALS CAN BE EXPECTED UNDER THUNDERSTORMS.

THEN WE SHOULD START TO EXPERIENCE A SLIGHT DRYING TREND FROM
SOUTHWEST TO NORTHEAST ON SUNDAY AND EVEN MORE SO ON MONDAY, AS THE
UPPER LOW SLIDES FROM SOUTHERN UTAH TO NORTHEASTERN COLORADO AND
UPPER RIDGING ARRIVES FROM THE WEST. EVEN THOUGH LOWER-LEVEL
MOISTURE WILL LIKELY REMAIN ACROSS SOME AREAS TUESDAY AND PERHAPS
INTO WEDNESDAY, SOUNDINGS INDICATE ENOUGH WARMING ALOFT TO CAP ANY
CONVECTION. THE TEMPERATURE ROLLER COASTER WILL CONTINUE THROUGH THE
FORECAST PERIOD, AS WE GO FROM 5-10 DEGREES BELOW NORMAL FRIDAY
THROUGH SATURDAY TO ABOVE NORMAL WEDNESDAY IF NOT TUESDAY.
&&

.AVIATION...FOR MCCARRAN...LIGHT AND VARIABLE WINDS TO START THE DAY
WITH DIRECTIONS GRADUALLY FAVORING NORTHEAST BY MID-MORNING.
DIRECTIONS SHOULD VEER TO A MORE EASTERLY OR POSSIBLY SOUTHEASTERLY
DIRECTION IN THE 17-20Z PERIOD WITH SPEEDS MOSTLY REMAINING AOB 10
KTS. HOWEVER, BEFORE STRONGER S/SSE WINDS KICK IN AROUND 20Z, E OR
SE GUSTS 10-20 KTS ARE POSSIBLE AT TIMES, AS HAS BEEN OBSERVED
OCCASIONALLY IN PAST SIMILAR SCENARIOS. MOST GUIDANCE SUGGESTS
MOSTLY SOUTHERLY WINDS BY 20Z BEFORE A GRADUAL TRANSITION TO
SOUTHWEST AFTER 03Z THURSDAY. HOWEVER, HI-RES LOCAL/NATIONAL MODELS
KEEP A MORE SOUTHEASTERLY COMPONENT (DIRECTIONS 140-170) THROUGH
AROUND SUNSET. THIS HAS HAPPENED IN PAST EVENTS, SO FORECAST LEANS
IN THIS DIRECTION FOR NOW WITH SOMEWHAT LOW CONFIDENCE. SPEEDS
GENERALLY 10-20 KTS WITH GUSTS 20-30 KTS IN THE 20Z-03Z TIME FRAME.
THEREAFTER, SSW WINDS 7-12 KTS ARE FORECAST OVERNIGHT WITH ONLY
MEDIUM CONFIDENCE BASED ON MODEL FORECAST VARIABILITY. MOSTLY SCT-
BKN HIGH CLOUDS THROUGH THE PERIOD. MECHANICAL TURBULENCE IS LIKELY
THIS AFTERNOON AND EVENING.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...DEEP LARGE-SCALE TROUGH IN THE EASTERN PACIFIC BEGINS
TO AFFECT THE AREA TODAY AS SOUTH WINDS INCREASE IN ADVANCE OF THE
APPROACHING SYSTEM. SPEEDS OF 10-20 KTS WITH GUSTS 20-30 KTS ARE
EXPECTED DURING THE AFTERNOON AND EARLY EVENING IN MOST OF THE
REGION EXCEPT THE SOUTHERN GREAT BASIN AND THE OWENS VALLEY WHERE
SPEEDS/GUSTS WILL BE SOMEWHAT HIGHER. SPEEDS SHOULD DIMINISH
SOMEWHAT OVERNIGHT BUT MAY CONTINUE TO GUST ABOVE 20 KTS IN INYO AND
SAN BERNARDINO COUNTIES. MOSTLY SCT-BKN HIGH CLOUDS THROUGH THE
PERIOD WITH POTENTIALLY LOWER CIGS AND SOME MOUNTAIN OBSCURATIONS IN
THE SIERRA BY EVENING. MECHANICAL TURBULENCE IS LIKELY THIS
AFTERNOON AND EVENING.
&&

.SPOTTER INFORMATION STATEMENT...ACTIVE WEATHER IS EXPECTED OVER THE
WEEKEND. SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT WEATHER
ACCORDING TO STANDARD OPERATING PROCEDURES.
&&

$$

DISCUSSION...GORELOW/PADDOCK/SHAFER
AVIATION...SHAFER


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.