Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 050857
AFDVEF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
157 AM PDT WED AUG 5 2015

.SYNOPSIS...DRY CONDITIONS ARE EXPECTED AREA WIDE TODAY. MONSOON
MOISTURE WILL BEGIN TO PUSH UP THE COLORADO RIVER VALLEY THURSDAY
AND SWEPT EAST FRIDAY. THIS WILL RESULT IN CHANCES FOR SHOWERS AND
THUNDERSTORMS GENERALLY ALONG AND EAST OF THE COLORADO RIVER
THURSDAY...THEN EAST OF LAS VEGAS ON FRIDAY. A FEW ISOLATED STORMS
WILL BE POSSIBLE OVER THE SIERRA THURSDAY AND FRIDAY. DRY CONDITIONS
WILL RETURN THIS WEEKEND.
&&

.SHORT TERM...TODAY THROUGH FRIDAY NIGHT.

TODAY...ALL IN ALL PRETTY QUIET CONDITIONS ARE EXPECTED TO PERSIST
TODAY WITH JUST SOME ELEVATED SOUTHWESTERLY BREEZES COURTESY OF A
WAVE THAT IS EXPECTED TO MOVE THROUGH NORTHERN CALIFORNIA AND
NORTHERN NEVADA OVER THE NEXT 24-36 HOURS. THE ONLY OTHER IMPACT
FROM THIS SYSTEM WILL BE A BAND OF HIGH CLOUDS DRAPED ACROSS THE
NORTHWESTERN THIRD OF THE FORECAST AREA.

THURSDAY...AS THE AFOREMENTIONED WAVE MOVES EAST OF THE REGION ON
THURSDAY THE DOOR WILL OPEN FOR SOME LOW TO MODERATE GRADE MONSOON
MOISTURE TO PUSH ITS WAY NORTH UP THE COLORADO RIVER VALLEY. A WEAK
VORT LOBE ROTATING NORTH AROUND HIGH PRESSURE OVER NEW MEXICO COULD
AID IN TRIGGERING CONVECTION OVER OUR FORECAST AREA BY LATE THURSDAY
AFTERNOON EAST OF THE COLORADO RIVER VALLEY. THIS FEATURE ALONG WITH
THE ADVECTION OF MOISTURE NORTHWARD MAY KEEP THUNDERSTORM CHANCES
GOING DURING THURSDAY NIGHT...MAINLY EAST OF A RACHEL-MT CHARLESTON-
ESSEX LINE. ADJUSTMENTS WERE MADE TO INCREASE THE AREAL EXTENT OF
PRECIP CHANCES FOR THIS TIME PERIOD. ALSO WORTH NOTING IS THAT
FARTHER WEST OVER ESMERALDA AND NORTHERN INYO COUNTIES THERE WILL BE
ISOLATED CHANCES FOR CONVECTION DUE TO DIFLUENT FLOW AHEAD OF A MORE
VIGOROUS CLOSED LOW THAT WILL BE MOVING JUST SOUTH OF THE BAY AREA
BY 12Z FRIDAY.

FRIDAY...THE CLOSED LOW NEAR THE BAY AREA WILL LIFT NORTHEAST INTO
NORTHERN NEVADA BY FRIDAY NIGHT...BRINGING STRONGER SOUTHWESTERLY
FLOW (INCLUDING SURFACE WINDS) TO THE REGION FRIDAY. THIS WILL
ACCOMPLISH TWO THINGS. FIRST...IT SHOULD EFFECTIVELY DRY THE REGION
OUT BY LATE FRIDAY NIGHT. MORE IMPORTANTLY IT WILL ACT TO ENHANCE A
MOIST-DRY BOUNDARY ORIENTED NORTH-NORTHWEST TO SOUTH-SOUTHEAST
ACROSS THE REGION DURING THE DAY FRIDAY. JUST WHERE THIS BOUNDARY
SETS UP WILL BE CRITICAL TO THUNDERSTORM COVERAGE ON FRIDAY. CURRENT
CONSENSUS PLACES THIS BOUNDARY OVER WESTERN LINCOLN AND CLARK
COUNTIES AT 12Z FRIDAY...OVER LAS VEGAS BY 18Z...AND JUST EAST OF
MESQUITE BY 00Z. THIS MEANS THAT ANY CHANCE FOR THUNDERSTORMS IN LAS
VEGAS WILL BE LARGELY OVER BY LATE MORNING. TO THE EAST OF THIS
BOUNDARY CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASE
DRAMATICALLY...PARTICULARLY DURING THE AFTERNOON ACROSS EASTERN
LINCOLN COUNTY...FAR EASTERN CLARK COUNTY AS WELL AS CENTRAL AND
NORTHERN MOHAVE COUNTY. STORM MOTION OF 25-30 MPH WILL SIGNIFICANTLY
REDUCE THE THREAT OF FLASH FLOODING FROM INDIVIDUAL STORMS...HOWEVER
TRAINING STORMS WILL NEED TO BE WATCHED. INSTEAD STRONG/SEVERE WINDS
AND HAIL COULD BE THE LARGER THREATS WITH STORMS...ESPECIALLY ACROSS
LINCOLN AND NORTH EAST CLARK WHERE 0-6KM SHEAR VALUES OF 25-40 KTS
WILL BE IN PLACE THANKS TO A JET STREAK ASSOCIATED WITH THE CLOSED
LOW. STORMS ARE LIKELY TO BE DISCRETE (RATHER THAN A SOLID LINE) DUE
TO THE ORIENTATION OF THE DEEP LAYER SHEAR TO THE MOISTURE BOUNDARY.
AGAIN...THIS LINE IS EXPECTED TO SHIFT EAST RAPIDLY FRIDAY AFTERNOON
INTO FRIDAY EVENING...WITH ACTIVITY ENDING BETWEEN 03Z AND 06Z
SATURDAY. CHANGES WERE MADE TO THE GOING FORECAST TO ACCOUNT FOR
THIS PROGRESSION...INCLUDING ADDING A SLIGHT CHANCE OF PRECIPITATION
IN LAS VEGAS ON FRIDAY MORNING.

.LONG TERM...SATURDAY THROUGH WEDNESDAY.

A DRY SOUTHWEST FLOW WILL BE OVER THE ENTIRE FORECAST AREA SATURDAY
THROUGH MONDAY. LATEST MODELS CONTINUE TO INDICATE SOUTHERLY FLOW
WILL DEVELOP LATE MONDAY, BRINGING MOISTURE NORTHWARD INTO MAINLY
MOHAVE COUNTY. SHOWER AND THUNDERSTORM DEVELOPMENT WILL BE POSSIBLE
TUESDAY AFTERNOON AND EVENING ACROSS NORTHWEST ARIZONA. SOUTHERLY
FLOW APPEARS TO STICK AROUND THROUGH WEDNESDAY. THERE IS UNCERTAINTY
IN JUST HOW FAR WEST THAT MOISTURE MAY PUSH, AS MODELS DIFFER ON THE
POSITION OF A MID-WEEK WEST COAST TROUGH. WILL SIDE WITH THE NAEFS
ENSEMBLE MEAN AND KEEP SHOWER AND THUNDERSTORM CHANCES GENERALLY
CONFINED TO MOHAVE COUNTY FOR WEDNESDAY, BUT THOSE CHANCES MAY
EXPAND WEST. AS FOR TEMPERATURES, NEAR TO SLIGHTLY BELOW NORMAL
VALUES ARE EXPECTED, WITH BREEZY SOUTH TO SOUTHWEST WINDS EACH
AFTERNOON AND EARLY EVENING.
&&

.AVIATION...FOR MCCARRAN...SOUTHWESTERLY WINDS ARE EXPECTED TO
PERSIST THROUGH THE DAY TODAY...BECOMING GUSTY DURING THE AFTERNOON.
OUTSIDE OF WINDS NO SIGNIFICANT WEATHER IS EXPECTED THROUGH THURSDAY
AFTERNOON. REMOTE CHANCES FOR SHOWER/THUNDERSTORMS WILL RETURN
THURSDAY NIGHT THROUGH FRIDAY MORNING.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...WINDS FAVORING A SOUTH/SOUTHWEST DIRECTION ARE EXPECTED
TODAY...BECOMING GUSTY DURING THE AFTERNOON. OUTSIDE OF WINDS NO
SIGNIFICANT WEATHER IS EXPECTED TODAY. CHANCES FOR THUNDERSTORMS
WILL INCREASE ALONG AND EAST OF THE COLORADO RIVER THURSDAY.
&&

.SPOTTER INFORMATION STATEMENT...SPOTTERS ARE ENCOURAGED TO REPORT
ANY SIGNIFICANT WEATHER CONDITIONS ACCORDING TO STANDARD OPERATING
PROCEDURES.
&&

$$

SHORT TERM/AVIATION...WOLCOTT
LONG TERM.............PADDOCK

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