Severe Thunderstorm Warning 52, NWS Phoenix, AZ

AZZ020>028-CAZ030>033-250545-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
255 PM MST THU AUG 24 2000

.SYNOPSIS...
HIGH PRESSURE ALOFT IS EXPECTED TO CONTINUE CENTERED AROUND COLORADO
AND OKLAHOMA THE REST OF THE WEEK AND EARLY NEXT WEEK. THIS WILL
CONTINUE A MOIST FLOW OF AIR FROM THE SOUTHEAST OVER ARIZONA AND
SOUTHEAST CALIFORNIA. A LOW PRESSURE SYSTEM IN THIS FLOW IS EXPECTED
TO HELP ENHANCE THUNDERSTORMS WITH LOCALLY HEAVY RAIN OVER PORTIONS
OF SOUTHEAST CALIFORNIA INTO THIS EVENING. ANOTHER LOW PRESSURE
SYSTEM IS EXPECTED TO ENHANCE THUNDERSTORMS OVER SOUTH-CENTRAL
ARIZONA LATE TONIGHT THROUGH FRIDAY NIGHT.

.DISCUSSION...
THE GENERAL FLOW ALOFT FROM THE SOUTHEAST WITH MOIST AND UNSTABLE AIR
CONTINUES OVER ARIZONA AND SOUTHEAST CALIFORNIA. A LOW PRESSURE
SYSTEM IN THIS FLOW HAS ENHANCED THUNDERSTORMS WITH SOME HEAVY RAIN
IN PORTIONS OF SOUTHEAST CALIFORNIA WHICH IS EXPECTED TO CONTINUE
INTO THIS EVENING. FLASH FLOODING WAS REPORTED IN JOSHUA TREE
NATIONAL PARK THIS AFTERNOON. A HAZARDOUS WEATHER OUTLOOK WAS ISSUED
A FEW HOURS BEFORE THIS EVENT EMPHASIZING FLOODING OF NORMALLY DRY
CREEKS AND WASHES IN SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA THIS
AFTERNOON AND EVENING. THE NEXT SYSTEM FROM NORTHERN MEXICO AND FAR
SOUTHWEST TEXAS NEAR EL PASO IS EXPECTED TO AFFECT SOUTH-CENTRAL
ARIZONA LATE TONIGHT CONTINUING WITH ENHANCEMENT OF SHOWERS AND
THUNDERSTORMS THROUGH FRIDAY NIGHT WHICH IS COVERED IN THE FORECAST.
CONTINUING SIMILAR BROAD BRUSH EXTENDED FORECAST SUNDAY THROUGH
TUESDAY AS MORE MOISTURE FROM MEXICO MOVES INTO THE SOUTHWESTERN U.S.

ELLIS

AZZ020>028-CAZ030>033-250215-

HAZARDOUS WEATHER OUTLOOK...UPDATED...
NATIONAL WEATHER SERVICE PHOENIX AZ
121 PM MST (121 PM PDT) THU AUG 24 2000

...SLIGHT RISK OF HAZARDOUS WEATHER OVER SOUTH CENTRAL AND
SOUTHWEST ARIZONA...AND EXTREME SOUTHEAST CALIFORNIA THIS AFTERNOON
AND TONIGHT...

COUNTIES IN THE RISK AREA INCLUDE:
    IN ARIZONA...MARICOPA...SOUTHERN GILA...NORTHWEST PINAL...
    LA PAZ...AND YUMA.
    IN CALIFORNIA...IMPERIAL AND EASTERN RIVERSIDE.

THE PRIMARY HAZARDOUS WEATHER RISKS INCLUDE:
    THUNDERSTORMS PRODUCING WIND GUSTS IN EXCESS OF 60 MPH.
    BLOWING DUST REDUCING VISIBILITY TO LESS THAN ONE QUARTER MILE.
    HEAVY RAIN THAT COULD CAUSE FLOODING zOF STREETS AND NORMALLY
    DRY CREEKS AND WASHES.

STORM SPOTTER ACTIVATION MAY BE NECESSARY LATER TODAY.

MB