Severe Thunderstorm Warning 20, NWS Las Vegas, NV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
244 PM PDT TUE AUG 17 2004

.SYNOPSIS...AN UNSEASONABLY STRONG UPPER LEVEL LOW NEAR SALT LAKE
CITY WILL WEAKEN AND MOVE SLOWLY EAST...REACHING THE HIGH PLAINS BY
THURSDAY. DRIER AIR HAS OVERSPREAD MUCH OF THE SOUTHERN GREAT BASIN
IN THE WAKE OF THE LOW...LIMITING THUNDERSTORM DEVELOPMENT THERE.
OVER THE MOJAVE DESERT...MOIST UNSTABLE AIR REMAINS IN PLACE...AND
THUNDERSTORMS WILL REMAIN A THREAT FOR ONE MORE DAY UNTIL DRIER AIR
MOVES IN THERE AS WELL. TEMPERATURES WILL SLOWLY MODERATE...RISING
TO NEAR SEASONAL AVERAGES BY THURSDAY. A WEAK STORM SYSTEM WILL
AFFECT THE SOUTHERN GREAT BASIN THURSDAY THROUGH SATURDAY...BRINGING
SMALL CHANCES FOR THUNDERSTORMS MAINLY OVER THE MOUNTAINS.
&&

.SHORT TERM...SORT OF AN ACTIVE DAY OVER THE SOUTHEAST THIRD OF THE
CWFA...BUT NOWHERE NEAR THE COVERAGE AND INTENSITY OF STORMS WHICH
WERE SEEN THE PAST SEVERAL DAYS. DRIER AIR WRAPPING IN BEHIND THE
UPPER LOW WHICH HAS FINALLY EXITED THE AREA HAS SQUASHED STORM
DEVELOPMENT OVER MUCH OF THE CWFA. IN THE SOUTHEAST...SATELLITE
PRECIPITABLE WATER ESTIMATES ARE STILL RUNNING 1.5 TO 2 INCHES AND
STORMS HAVE IGNITED IN THE JUICY AIR. STORMS OVER NORTHERN MOHAVE
COUNTY ARE BEING INFLUENCED BY THE BELT OF WESTERLIES SOUTH OF THE
UPPER LOW...AND ARE MOVING EAST. FARTHER SOUTH...IN SAN BERNARDINO
AND SOUTHERN MOHAVE COUNTIES...STEERING FLOW IS WEAKER AND STORM
MOVEMENT IS SLOWER. IF THERE IS ANY FLOODING THIS EVENING...IT WILL
BE ISOLATED...UNLIKE THE PAST SEVERAL DAYS. THE DRYING TREND SHOULD
CONTINUE...ALBEIT SLOWLY...THROUGH TOMORROW. ON THURSDAY...THE
MODELS SHOW A WEAK NORTHERN STREAM SHORTWAVE DROPPING DOWN INTO THE
NORTHERN CWFA...AND WILL INCLUDE SLIGHT CHANCE TO CHANCE POPS OVER
THE MOUNTAINS THERE. POINT TEMPERATURES WILL BE CHALLENGING DUE TO
EFFECTS FROM PAST STORMS /SATURATED SOILS AND LOWER DIURNAL RANGES/
AND CURRENT STORMS /COOL STORM OUTFLOW/. OVERALL TREND SHOULD BE A
SLOW RISE AS THE AIRMASS DRIES OUT.
&&

.LONG TERM...MODELS IN DECENT AGREEMENT WITH A WEAK SYSTEM MOVING
INTO THE PACNW ON SATURDAY...THEN DIFFER WIDELY AFTER THAT. DGEX AND
GFS DEVELOP A WEAK TROUGH OFF THE WEST COAST...WHILE THE EURO AND
UKMET DEVELOP A MUCH STRONGER LOW AND MOVE IT THROUGH THE PACNW. 12Z
GFS RUN MAY BE COMING AROUND TO THE EURO/UKMET SOLUTION BUT IT
DIFFERS GREATLY IN HOW IT HANDLES THE PACNW SYSTEM. BY TUESDAY THE
GFS CLOSES THIS SYSTEM OFF OVER CENTRAL CALIFORNIA...SIMILAR TO THE
SYSTEM WE EXPERIENCED YESTERDAY BUT WITHOUT ALL THE MOISTURE. EURO
IS MUCH FURTHER NORTH. FOR NOW WILL KEEP A DRY FORECAST UNTIL MODELS
COME INTO BETTER AGREEMENT. LOOKS AS IF MONSOONAL MOISTURE WILL
REMAIN OUT OF THE FORECAST AREA UNDER THE INFLUENCE OF THE
TROUGH/LOW.
&&

.AVIATION...TAF ADEQUATELY COVERS ALL SIGNIFICANT WEATHER EXPECTED
AT KLAS.
&&

.VEF WATCHES/WARNINGS/ADVISORIES...
.NV...NONE.
.AZ...NONE.
.CA...NONE.
&&

MORGAN/DAVIS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE LAS VEGAS NV
200 PM PDT TUE AUG 17 2004

AZZ001>003-036-CAZ026>029-NVZ014>022-181700-
DEATH VALLEY NATIONAL PARK-ESMERALDA AND CENTRAL NYE COUNTY-
LAKE HAVASU AND FORT MOJAVE-LAKE MEAD NATIONAL RECREATION AREA-
LAS VEGAS VALLEY-LINCOLN COUNTY-NORTHEAST CLARK COUNTY-
NORTHWEST DESERTS-NORTHWEST PLATEAU-
OWENS VALLEY AND ADJACENT EASTERN SIERRA SLOPES-
SAN BERNARDINO COUNTY DESERTS-SAN BERNARDINO COUNTY-
UPPER COLORADO RIVER VALLEY-SHEEP RANGE-SOUTHERN CLARK COUNTY-
SPRING MOUNTAINS-RED ROCK CANYON-
WESTERN CLARK AND SOUTHERN NYE COUNTY-
200 PM PDT (200 PM MST) TUE AUG 17 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST
CALIFORNIA/SOUTHERN NEVADA AND NORTHWEST ARIZONA.

.DAY ONE...TODAY.

SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE THIS AFTERNOON AND
EVENING...PARTICULARLY ALONG AND SOUTHEAST OF INTERSTATE 15. ALTHOUGH
THE THREAT OF WIDESPREAD HAZARDOUS WEATHER IS LOW...ISOLATED HEAVY
RAIN AND FLASH FLOODING CANNOT BE RULED OUT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

DRIER AIR WILL SLOWLY PUSH IN FROM THE WEST ON WEDNESDAY...LIMITING
THE THREAT OF THUNDERSTORMS TO PORTIONS OF LINCOLN AND MOHAVE
COUNTIES. FOR THURSDAY THROUGH MONDAY...THE PROBABILITY OF WIDESPREAD
HAZARDOUS WEATHER IS LOW.

MORGAN