Severe Thunderstorm Warning 6, NWS Las Vegas, NV

MOJAVE DESERT/SOUTHERN GREAT BASIN AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
250 PM PDT SUN AUG 22 1999

SYNOPSIS...A LOW PRESSURE SYSTEM ALONG THE CALIFORNIA COAST AND A
RIDGE OF HIGH PRESSURE OVER THE ROCKIES WILL MAINTAIN A FLOW OF MOIST
AND UNSTABLE AIR ACROSS THE REGION INTO TUESDAY. THIS WILL RESULT IN
A CONTINUED THREAT FOR AFTERNOON AND EVENING THUNDERSTORMS EACH DAY.

DISCUSSION...MODELS IN GOOD AGREEMENT TODAY WITH SYNOPTIC SCALE
PATTERN. CLOSED LOW OFF CENTRAL CA COAST REMAINS IN PLACE INTO MONDAY
WITH RIDGE OVER THE ROCKIES. UPPER LOW THEN BEGINS TO OPEN UP AND
LIFT ACROSS NRN CA MON NGT/TUE.  NGM/ETA MODELS NOW CONSISTENTLY
SHOWING LITTLE OR NO DRYING WITH THE DEPARTING LOW AND LESS
WIND/WEAKER GRADIENTS FOR MON/TUE. NOT BUYING INTO THE STRONGER SW
FLOW AND DRYING INDICATED ON AVN FOR TUE.

IN THE SHORT TERM...SCATTERED STORMS FIRING UP THIS AFTERNOON AND
QUESTION IS WHETHER OR NOT UPPER JET MAX ACROSS CA/NV WILL AGAIN
PROVIDE DIVERGENCE TO CONTINUE STORMS THRU THE EVENING OR EVEN AID
NOCTURNAL STORMS. GIVEN THE SLIGHTLY BETTER TRACK RECORD OF THE ETA
LAST NIGHT...IT WAS FOLLOWED AND SUGGESTS THIS WILL AGAIN BE THE
CASE.  ETA SHOWS HIGH CAPE VALUES AND NEARBY UPPER DIVERGENCE ACROSS
SRN NV OVERNIGHT AGAIN...WITH THE BEST UPPER SUPPORT OVER SOUTH
CENTRAL NV ZONES. WORDED FORECASTS WITH MAINLY EVENING FOR STORMS
ACROSS NV TO EXPRESS UNCERTAINTY IN TIMING.  FOR MON/TUE...CANNOT NOT
SEE MUCH CHANGE WITH MOISTURE REMAINING INTACT TO HELP FIRE AFT/EVE
STORMS. IN FACT...HIGHER PRECIPITABLE WATER VALUES LURKING ALONG NRN
MEXICO AND NRN GULF OF CA MAY YET MAKE ANOTHER SURGE INTO THE REGION
TONIGHT OR MON NIGHT.  DEFINITELY NO STRONG DRYING TREND INDICATED SO
PERSISTENCE FORECAST SEEMS BEST FOR STORMS WITH LITTLE CHANGE IN
TEMPS.

IN THE EXTENDED...MRF AND ECMWF IN DECENT AGREEMENT KEEPING BROAD
UPPER RIDGE ACROSS WRN STATES WED/THU...AMPLIFYING THE RIDGE OVER THE
ROCKIES AGAIN FRI AS ANOTHER SHORT WAVE APPROACHES WEST COAST.  WITH
NO STRONG DRYING TREND INDICATED AND MOISTURE AGAIN POOLING OVER NRN
MEXICO...FEEL STANDARD MID-AUGUST FORECAST CALLED FOR WITH SOME
MENTION OF STORMS EACH DAY...ESPECIALLY ACROSS NV/AZ ZONES.

NEMETH

.LAS...NONE.