Flash Flood Watch 6, NWS Las Vegas, NV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
325 PM PDT MON AUG 11 2014

.SYNOPSIS...MONSOON MOISTURE PUSHING IN FROM THE SOUTHEAST WILL
RESULT IN INCREASED THUNDERSTORM COVERAGE THROUGH WEDNESDAY. DRIER
AIR WILL ONCE AGAIN GRADUALLY MOVE IN FROM THE SOUTHWEST STARTING
THURSDAY WITH THUNDERSTORM CHANCES CONFINED TO MOHAVE COUNTY BY
FRIDAY.
&&

.SHORT TERM...THROUGH TUESDAY NIGHT...
TAIL END OF LINE OF STORMS WHICH WAS OVER INYO/ESMERALDA COUNTY THIS
MORNING DID SHIFT EASTWARD AND DID AFFECT SRN NYE/CLARK COUNTIES
THIS AFTERNOON. THOSE STORMS NOW MOVING INTO LINCOLN COUNTY.
ACTIVITY IS GETTING GOING OVER MOHAVE COUNTY WITH
MORE STORMS SET TO ENTER MOHAVE COUNTY FROM COCONINO/YAVAPAI
COUNTIES. HRRR SUGGEST THE NORTHERN TWO-THIRDS OF MOHAVE COUNTY WILL
REMAIN THE MOST ACTIVE FOR THE NEXT 3-4 HOURS THEN SHIFTING
NORTHWARD ACROSS NORTHEAST CLARK AND LINCOLN COUNTIES THIS EVENING.
GUSTS OF 40-50 MPH...SMALL HAIL AND BRIEF HEAVY RAIN POSSIBLE WITH
STORMS.

FOR TUESDAY...MODELS MORE OR LESS IN GOOD AGREEMENT SHOWING AN
INVERTED TROUGH MOVING EAST ACROSS SOUTHERN ARIZONA TONIGHT AND INTO
SOUTHWEST ARIZONA LATE TUESDAY AFTERNOON. INVERTED TROUGH THEN
ENCOUNTERS A MORE WESTERLY FLOW AND LIFT NORTH ACROSS WESTERN
ARIZONA TUESDAY NIGHT/WEDNESDAY. DUE TO ADDITIONAL DYNAMICS DECIDED
TO ISSUE A FLASH FLOOD WATCH FOR THE NORTHWEST DESERT AND PLATEAU OF
MOHAVE COUNTY FROM 11 AM MST - 10 PM MST TUESDAY. TOMORROW WE WILL
BE LOOKING AT THE NEED OF EXTENDING THE WATCH INTO WEDNESDAY IF
MODELS STAY CONSISTENT.

.LONG TERM...WEDNESDAY THROUGH SUNDAY...THE SYNOPTIC PATTERN
FEATURES A LOW PRESSURE TROUGH OVER THE PACIFIC NW WEDNESDAY THAT IS
FORECAST TO MOVE INTO THE NORTHERN GREAT BASIN THURSDAY AND FRIDAY.
THE UPPER LEVEL FLOW BECOMES SOLIDLY WEST TO SOUTHWEST AS THE WEEK
WEARS ON. THE AFFECT OF THIS LARGE SCALE FEATURE ON SENSIBLE WEATHER
WITHIN THE FORECAST AREA IS TO BRING A DECREASING TREND IN
THUNDERSTORM COVERAGE.

WEDNESDAY HAS THE BEST POTENTIAL FOR SCATTERED THUNDERSTORMS ACROSS
A WIDER AREA INCLUDING LINCOLN, CLARK, MOHAVE AND EASTERN SAN BERN
COUNTIES. BEYOND WEDNESDAY, RAPID DRYING TAKES PLACE IF THE GFS
VERIFIES BUT COULD BE SOMEWHAT SLOWER PER THE ECMWF. MAINTAINED A
MENTION OF STORMS IN MOHAVE COUNTY BOTH THURSDAY AND FRIDAY BEFORE
DRYING THEM OUT COMPLETELY OVER THE WEEKEND. TEMPERATURES WILL
GENERALLY BE BELOW NORMAL MID TO LATE IN THE WEEK THEN BECOME
SEASONAL OVER THE WEEKEND.
&&

.AVIATION...FOR MCCARRAN...OUTFLOW WINDS FROM SURROUNDING STORMS
WILL CONTINUE TO AFFECT LAS VEGAS VALLEY TERMINALS INTO THE EVENING
HOURS. LOOKS LIKE WINDS WILL FAVOR A NORTHERLY DIRECTION FOR SEVERAL
HOURS BEFORE TRANSITION BACK TO OUR TYPICAL SOUTH/SOUTHWEST
DIRECTION WITH SPEEDS OF 7-11 KTS. CONVECTION SHOULD IMPACT MAINLY
THE BEATTY...MORMON MESA AND PEACH SPRINGS CORRIDORS THIS EVENING.
THERE WILL BE ANOTHER CHANCE OF SHOWERS OR TSTORM WITHIN THE
VICINITY OF THE TERMINAL TUESDAY...WHICH COULD BRING GUSTY AND
ERRATIC WINDS.

FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...SCATTERED-BROKEN CLOUDS ALONG WITH ISOLATED TO
SCATTERED THUNDERSTORMS ACROSS ALL OF SOUTHEAST
CALIFORNIA...SOUTHERN NEVADA AND NORTHWEST ARIZONA THIS EVENING AND
AGAIN TUESDAY. WINDS WILL FAVOR TYPICAL DIURNAL WIND PATTERNS
THROUGH TUESDAY...EXCEPT NEAR THUNDERSTORMS.
&&

.SPOTTER INFORMATION STATEMENT...SPOTTERS SHOULD REPORT INSTANCES OF
FLASH FLOODING...STRONG GUSTY WINDS...HAIL...AND BLOWING DUST TODAY
THROUGH TUESDAY.
&&

SHORT TERM/AVIATION...PIERCE
LONG TERM...SALMEN

FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE:

HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER