Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 141105
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
405 AM PDT MON JUL 14 2014

.SYNOPSIS...A MOIST SOUTHEAST FLOW HAS RETURNED TO THE REGION AND
WILL LEAD TO EXPANDING THUNDERSTORM COVERAGE TODAY AND TUESDAY.
TEMPERATURES WILL ALSO TREND COOLER WITH THE INCREASING MOISTURE.
ISOLATED THUNDERSTORMS CAN BE EXPECTED THROUGH THE MIDDLE OF THE
WEEK FOLLOWED BY A DRYING TREND TOWARD THE WEEKEND.
&&

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT...IR SATELLITE LOOPS
SHOWED A DECAYING THUNDERSTORM COMPLEX OVER NORTHERN SONORA AND
SOUTHWEST ARIZONA HAD PUSHED A BOUNDARY UP ACROSS EASTERN SAN
BERNARDINO AND SOUTHERN CLARK COUNTIES THIS MORNING. THIS WAS
ASSOCIATED WITH THE CREST OF THE INVERTED TROUGH LIFTING TOWARD
SOUTHERN CALIFORNIA AND WAS COLLIDING WITH EASTERLY FLOW ALREADY IN
PLACE ACROSS NORTHWEST ARIZONA AND SOUTHERN NEVADA. ISOLATED LIGHT
SHOWERS AND A FEW THUNDERSTORMS HAVE BEEN PERSISTENT OVERNIGHT BUT
RADAR RETURNS AT 1030Z SHOWED A BAND OF SHOWERS AND THUNDERSTORMS
BECOMING MORE DEVELOPED ALONG THE AFOREMENTIONED BOUNDARY FROM
CENTRAL CLARK COUNTY ACROSS LAKE MEAD INTO NORTHERN MOHAVE COUNTY.
THIS AREA SHOULD BE FAIRLY ACTIVE THROUGH SUNRISE. LOCALIZED GUSTS
AROUND 45 MPH HAVE BEEN OCCURRING NEAR SOME SHOWER DURING THE PAST
FEW HOURS. AS THE DAY GOES ON...THE INVERTED TROUGH LIFTING UP
THROUGH SOUTHERN CALIFORNIA SHOULD HELP PRODUCE SCATTERED
THUNDERSTORMS ACROSS SAN BERNARDINO AND INYO COUNTIES. POPS WERE
RAISED TO AROUND 30 PERCENT. THERE IS POTENTIAL FOR LATE AFTERNOON
AND EVENING THUNDERSTORMS PUSHING OUT OF NORTHWEST ARIZONA INTO
SOUTHERN NEVADA IN THE EASTERLY FLOW AND SOME HIGH RES MODELS ARE
INDICATING THIS.

FOR TUESDAY...A MOIST AND UNSTABLE AIR MASS WILL REMAIN IN PLACE
ACROSS THE ENTIRE REGION. THE NAM INDICATES CONSIDERABLE MID LEVEL
CONVERGENCE OVER CENTRAL NEVADA TUESDAY AFTERNOON BUT THERE IS NO
OTHER READILY APPARENT MECHANISM TO ENHANCE CONVECTION OUTSIDE OF
OROGRAPHICS AND BOUNDARY INTERACTIONS. SOME DRYING AND STABILIZATION
IS INDICATED OVER SOUTHERN SAN BERNARDINO COUNTY...BUT THE REST OF
THE AREA SHOULD SEE ISOLATED TO SCATTERED THUNDERSTORMS PRIMARILY
DURING THE AFTERNOON AND EVENING WITH DIMINISHING ACTIVITY TUESDAY
NIGHT. NO SIGNIFICANT CHANGES WERE MADE TO THE FORECAST BEYOND
TUESDAY NIGHT.

TEMPERATURES WILL GENERALLY DROP SEVERAL DEGREES TODAY AND A FEW
MORE TUESDAY DUE TO EXTENSIVE CLOUD COVER...HIGHER DEWPOINTS AND
PRECIPITATION.

.LONG TERM...WEDNESDAY THROUGH SUNDAY...TWO WEAK UPPER LEVEL
DISTURBANCES WILL BE INFLUENCING OUR WEATHER ON WEDNESDAY. THE FIRST
WILL BE MOVING SOUTHEAST DOWN THE FRONT RANGE WHILE THE SECOND WILL
BE MOVING TO THE NORTHWEST OFF OF THE CALIFORNIA COAST. THOSE TWO
SYSTEMS WILL BE INFLUENCING WHERE THE MOISTURE BOUNDARY WILL BE. AT
THIS POINT DRIER AIR WILL BE MOVING INTO SOUTHEAST CALIFORNIA...BUT
REMAIN IN PLACE ACROSS MUCH OF SOUTHERN NEVADA AND NORTHWEST
ARIZONA. BY THURSDAY...THE DRIER AIR WILL NOSE A LITTLE FURTHER TO
THE NORTH AND THUNDERSTORMS CHANCE WILL DIMINISH MODESTLY IN MOST
LOCATIONS. BY FRIDAY WEAK RIDGING WILL BE IN PLACE AND THE DRYING
TREND WILL CONTINUE...LIMITING THE THUNDERSTORMS FURTHER AND
PRIMARILY OVER THE HIGH TERRAIN. SATURDAY LOOKS TO BE THE QUIETEST
DAY OF THE PERIOD AT THIS POINT AS THE RIDGE OF HIGH PRESSURE SLOWLY
SHIFTS TO THE EAST...BEING CENTERED OVER THE FOUR CORNERS REGION
SATURDAY AFTERNOON. BOTH THE GFS AND ECMWF INDICATE THE RIDGE
DROPPING FURTHER SOUTH AND EAST...SETTING THE STAGE FOR ANOTHER
RETURN OF MONSOON MOISTURE ON SUNDAY AND THE FLOW SHIFT TO THE
SOUTHEAST. TEMPERATURES WILL BE FAIRLY FLAT THROUGH THE PERIOD AND
WITHIN A COUPLE OF DEGREES OF THEIR SEASONAL NORMS.
&&

.AVIATION...FOR MCCARRAN...SCATTERED SHOWERS AND ISOLATED
THUNDERSTORMS OVER SOUTHERN NEVADA AND NORTHWEST ARIZONA THIS
MORNING WILL TRACK TOWARD THE WEST AT 20-25 KTS AND MAY AFFECT THE
TERMINAL AREA THROUGH AT LEAST 16Z. LOCALIZED WINDS GUSTS TO 40 KTS
WILL BE POSSIBLE NEAR SHOWERS. PREVAILING WINDS WILL BE FROM THE
SOUTHEAST TODAY AT 5-10 KTS. ISOLATED THUNDERSTORMS CAN BE EXPECTED
IN ALL APPROACH CORRIDORS DURING THE AFTERNOON AND EVENING. THE MOST
EXTENSIVE THUNDERSTORM DEVELOPMENT IS EXPECTED IN THE PEACH SPRINGS
CORRIDOR.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...AN INCREASINGLY MOIST AND UNSTABLE EAST TO SOUTHEAST
FLOW WILL CONTINUE TODAY AND MONDAY PROVIDING ISOLATED TO SCATTERED
THUNDERSTORMS. AREAS MOST FAVORABLE FOR EXTENSIVE THUNDERSTORM
DEVELOPMENT ARE SOUTHEAST CALIFORNIA AND NORTHWEST ARIZONA.
LOCALIZED GUSTS AROUND 40 KTS CAN BE EXPECTED NEAR ANY SHOWERS.
&&

.SPOTTER INFORMATION STATEMENT...SPOTTER ACTIVATION MAY BE REQUESTED
TODAY OR TUESDAY. SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT
WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.
&&

$$

SHORT TERM/AVIATION...ADAIR
LONG TERM...CZYZYK

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