Flash Flood Warning 45, NWS Las Vegas, NV

MOJAVE DESERT/SOUTHERN GREAT BASIN AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
150 PM PDT THU JUL 15 1999

SYNOPSIS...LINGERING MOISTURE AND A WEAK UPPER LEVEL DISTURBANCE OVER
SOUTHERN NEVADA WILL PROVIDE FUEL FOR SOME THUNDERSTORMS THROUGH THE
EVENING...MAINLY SOUTH CENTRAL NEVADA...NEAR THE SIERRA...AND IN
NORTHERN MOHAVE COUNTY ARIZONA. OTHERWISE INCREASING SOUTHWEST FLOW
WILL CAUSE HUMIDITY LEVELS TO SLOWLY DROP EACH OF THE NEXT FEW DAYS.

DISCUSSION...WEAK HIGH LEVEL SHEAR VORTICITY SPREADING ACROSS MID TO
LOW LEVEL CONVERGENCE ZONE FROM EASTERN SIERRA ACROSS SOUTH CENTRAL
NEVADA AND NORTHERN MOHAVE COUNTY THIS AFTERNOON HELPING FIRE LOW-END
SCATTERED THUNDERSTORMS. INSTENSITY OF ACTIVITY FAIRLY STRONG WITH
STILL GOOD MOISTURE LEVELS...GOOD CAPE...AND SOME ADDED DIRECTIONAL
SHEAR.  WILL HAVE TO MONITOR THIS AREA REMAINDER OF AFTERNOON AND
EVENING. CELL MOVEMENT IS ACTUALLY LESS THAN YESTERDAY.  WILL COVER
THIS WITH SCATTERED THUNDERSTORMS MAINLY THIS EVENING AND MENTION
WIND GUST POTENTIAL TO 40 MPH AND LOCALLY HEAVY RAIN. IN SPITE OF
SHARP MID LEVEL DRYING NOTED ON WATER VAPOR SATELLITE...THE LOWER
ATMOSPHERE REMAINS ADEQUATELY MOIST FOR AT LEAST ISOLATED
THUNDERSTORMS THROUGH EARLY EVENING MOST AREAS TO THE SOUTH.

RATE OF DRYING AN ISSUE TODAY. ETA STILL MAINTAINS HIGHEST LOW LEVEL
MOISTURE ACROSS CENTRAL AND EASTERN ZONES THROUGH SATURDAY MORNING...
WHILE AVN AND NGM SIMILARLY AGRESSIVE IN DRYING.  BELIEVE IT WILL
TAKE AT LEAST ANOTHER DAY OF SOUTHWEST FLOW ALOFT TO SEE SIGNIFICANT
SURFACE DRYING...DESERTS STILL APPEAR UNIFORMLY MOIST...SO ISOLATED
THUNDERSTORMS ACROSS MAINLY HIGHER TERRAIN FOR FRIDAY LOOKS VALID
AGAIN. PREFER IN-BETWEEN THE TWO CHOICES ON RATE OF DRYING.

WILL BANK ON SOUTHWEST FLOW FINALLY BEING STRONG ENOUGH SATURDAY AS
NEXT STRONG SHORT WAVE CARVES OUT DEEP LOW ACROSS NORTHERN OREGON TO
DROP DEWPOINTS BACK INTO THE 30S/40S WEST OF THE COLORADO AND 40S/50S
TO THE EAST. ONE REAL NICE THING WITH THIS: ALTHOUGH TEMPERATURES
WILL WARM A DEGREE OR TWO EACH DAY WITH THE DRYING...SLIGHT HEIGHT
FALLS WILL KEEP HEIGHTS AND THICKNESSES BELOW NORMAL.  SO WE WILL
BENEFIT BOTH FROM RETURN TO DRIER AND A LITTLE BELOW NORMAL
TEMPERATURES THROUGH THE WEEKEND.

PLAYING DRY EXTENDED THROUGH MONDAY BEFORE THE MRF BRINGS A SLUG OF
MID LEVEL MOISTURE AROUND PERIPHERY OF REBUILDING FOUR-CORNERS RIDGE
TUESDAY AND INTO MAINLY SOUTHERN AND EASTERN FORECAST ZONES. THIS
APPEARS RELATED TO EVENTUAL DECAYING TROPICAL SYSTEM NOW IN EASTERN
PACIFIC AND WILL MAKE THE FAR EXTENDED A BIT OF A GUESS FOR A WHILE.
MCQUEEN

.LAS...NONE.