Area Forecast Discussion
Issued by NWS Las Vegas, NV

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000
FXUS65 KVEF 181627 AAA
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
925 AM PDT FRI APR 18 2014

.SYNOPSIS...
AN AREA OF LOW PRESSURE APPROACHING THE SOUTHERN CALIFORNIA COAST
WILL MOVE ACROSS THE AREA TODAY AND SATURDAY. ISOLATED SHOWERS AND
THUNDERSTORMS POSSIBLE MAINLY IN CALIFORNIA AND THE HIGH DESERTS. A
SYSTEM EARLY NEXT WEEK WILL USHER IN STRONG WINDS TUESDAY.
&&

.UPDATE...OUR UPPER LOW IS JUST OFF THE SAN DIEGO COUNTY COAST THIS
MORNING. MID/HIGH LEVEL MOISTURE IS BEING PULLED NORTHWARD INTO
SOUTHERN NEVADA ALONG WITH A VORTICITY LOBE. SO FAR REGIONAL RADAR IS
QUITE ALONG WITH NO SURFACE REPORTS OF PRECIPITATION YET. MODELS IN
GOOD AGREEMENT INDICATING AN AXIS OF WEAK INSTABILITY/CAPE EXTENDING
FROM THE SOUTHERN SIERRA NEVADA CREST SOUTH INTO SAN BERNARDINO
COUNTY MOUNTAINS. OTHER AXIS LIES ALONG A STATIONARY BOUNDARY ACROSS
CENTRAL AND NORTHEAST NEVADA. GRIDS WERE UPDATED EARLIER AND NEW
TEXT PRODUCTS SENT.
&&

.AVIATION...FOR MCCARRAN...SOUTHEAST WINDS WILL PREVAIL THIS MORNING
BEFORE SWITCHING TO A MORE SOUTHERLY DIRECTION IN THE AFTERNOON.
SOME CUMULUS DEVELOPMENT WITH POSSIBLE SHOWERS OVER HIGHER TERRAIN
(SPRING AND SHEEP MOUNTAINS) WILL BEGIN THIS AFTERNOON. OTHERWISE A
OVERCAST WILL PREVAIL.

FOR THE REST OF SOUTHERN NEVADA...NW ARIZONA...AND SE CALIFORNIA...
CUMULUS DEVELOPING BETWEEN 10-15 KFT THIS AFTERNOON LEADING TO A
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS OVER SOUTHEAST CALIFORNIA
AND SOUTHERN NEVADA. THERE WILL BE A REPEAT FOR A SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS SATURDAY AFTERNOON.
&&

.PREV DISCUSSION...
300 AM PDT FRI APR 18 2014

.SHORT TERM [TODAY THROUGH SUNDAY NIGHT]...

TODAY HAS THE MAKINGS OF AN INTERESTING FORECAST. AN UPPER LEVEL LOW
PRESSURE SYSTEM OFF THE WEST COAST WILL MOVE INLAND AND ACROSS THE
AREA OVER THE NEXT 48 HOURS. STEEP MID-LEVEL LAPSE RATES WILL
ACCOMPANY THE LOW. WHAT IS INTERESTING IS THAT THE ONSHORE FLOW FROM
THE PACIFIC OVER THE LAST FEW DAYS HAS ALLOWED A MODEST MARINE
INFLUENCE TO CREEP INTO PORTIONS OF CENTRAL AND EASTERN SAN
BERNARDINO COUNTY. DEW POINTS IN THIS AREA ARE WELL INTO THE MID
40S. WITH SOUTHERLY FLOW NEAR THE SURFACE PICKING UP SPEED AS THE
UPPER LEVEL APPROACHES...WE EXPECT EVEN MORE MOIST ADVECTION INTO
THE AREA AS WELL. THIS IS LEADING TO AN INCREASED CHANCE FOR RAIN
AND THUNDERSTORM ACTIVITY...EVEN DOWN TO THE VALLEY FLOORS IN THIS
AREA. WESTERN INYO COUNTY WILL ALSO BE AN AREA THAT WILL SEE
INCREASED ACTIVITY AS WELL. THE STORM PREDICTION CENTER HAS PLACED
THE AREA IN A GENERAL THUNDERSTORM OUTLOOK AND OUR LOCAL CONVECTION
ALLOWING MODELS ALSO ARE INDICATING ACTIVITY AS WELL.
ELSEWHERE...SHOWERS WILL MAINLY BE CONFINED TO HIGHER TERRAIN.
LINCOLN...CENTRAL NYE AND MOHAVE COUNTIES MAY ALSO SEE CONVECTIVE
ACTIVITY INCREASE. HOWEVER THIS IS LIKELY TO BE A BIT LATER IN THE
DAY AND EVENING WHEN THE UPPER LOW MOVES INLAND. SATURDAY...THE LOW
WILL STILL BE EXITING THE AREA TO THE EAST. THESE AREAS WILL
CONTINUE TO SEE INCREASE SHOWER ACTIVITY BEFORE WANING INTO SUNDAY.

.LONG TERM [MONDAY THROUGH THURSDAY]...

TRANSIENT RIDGING AND A WELL
MIXED BOUNDARY LAYER WILL LIKELY LEAD TO TEMPERATURES 8-12 DEGREES
ABOVE NORMAL BY MONDAY AFTERNOON...MAKING IT THE WARMEST DAY OF THE
PERIOD.

THE NEXT PACIFIC TROUGH WILL REALLY BEGIN TO IMPACT THE
REGION ON TUESDAY...WITH WINDY CONDITIONS DEVELOPING ACROSS THE
FORECAST AREA. GFS TREND TOOL INDICATES THAT THIS THROUGH HAS
TRENDED A BIT SLOWER AND FURTHER NORTH OVER THE PAST FEW RUNS. THAT
SAID ENSEMBLE GUIDANCE SHOWS BELOW NORMAL CONFIDENCE IN BOTH THE
EXACT TIMING AND AMPLITUDE OF THE SYSTEM AND THUS A BROAD-BRUSHED
APPROACH WAS TAKEN WITH THE FORECAST. AT THIS POINT WIDESPREAD
ADVISORY LEVEL WINDS ARE INCLUDED IN THE FORECAST (GUSTS OVER 40
MPH)...WITH THE POTENTIAL FOR HIGHER WINDS PARTICULARLY IN FAVORED
DOWNSLOPE AREAS. WENT AHEAD AND ADDED IN WORDING FOR AREAS OF
BLOWING DUST WHICH CAN BE REFINED AS WE APPROACH THE EVENT. THESE
WINDY CONDITIONS MAY ALSO COMBINE WITH RH`S IN THE TEENS AND SINGLE
DIGITS TO BRING RED FLAG CONDITIONS TO AREAS WITH CRITICAL FUELS.
CURRENTLY MODELS ONLY INDICATE A SLIGHT CHANCE OF SHOWER ACTIVITY
OVER THE FAR NORTHERN PORTIONS OF THE FORECAST AREA.

NORTHWEST FLOW WILL COOL CONDITIONS TO NEAR OR EVEN JUST BELOW
NORMAL BY WEDNESDAY WITH DRY AND BREEZY CONDITIONS CONTINUING.

MODEL AGREEMENT FALLS OFF MORE DURING THE LATTER PART OF THE
WEEK...BUT THE GENERAL CONSENSUS IS WEAK RIDGING THROUGH THURSDAY
AND THE POTENTIAL FOR SOME MORE UNSETTLED CONDITIONS BY FRIDAY OR
THE WEEKEND.
&&

.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
AZ...NONE.
CA...NONE.
&&

$$


PIERCE/LERICOS/WOLCOTT

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