Severe Thunderstorm Warning 77, NWS Phoenix, AZ

AZZ020>028-CAZ030>033-062245-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX ARIZONA
915 AM MST SAT SEP 6 2003

.SYNOPSIS...
HIGH PRESSURE ALOFT WILL REMAIN ANCHORED OFF THE SOUTHERN CALIFORNIA
COAST...EXTENDING INTO SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA. A
LOW PRESSURE DISTURBANCE WILL MOVE EASTWARD ACROSS NORTHERN ARIZONA
TODAY. THIS DISTURBANCE WILL BRING SCATTERED THUNDERSTORMS ACROSS
NORTHERN ARIZONA...WITH A SLIGHT CHANCE OF THUNDERSTORMS DEVELOPING
OVER THE DESERTS AND HIGHER TERRAIN OF SOUTH CENTRAL ARIZONA TODAY.
SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA SHOULD BE MOSTLY SUNNY.
DRIER AND MORE STABLE AIR WILL BE OVER ALL OF OF SOUTHWEST ARIZONA
AND SOUTHEAST CALIFORNIA SUNDAY. A LOW PRESSURE SYSTEM WILL MOVE
INTO THE WESTERN STATES MONDAY...EXTENDING SOMEWHAT INTO ARIZONA.
THIS WILL LEAD TO A RENEWED THREAT FOR THUNDERSTORMS IN PARTS OF
SOUTHWEST AND SOUTH CENTRAL ARIZONA LATE MONDAY...INCREASING
TUESDAY. TEMPERATURES BY THE MIDDLE OF NEXT WEEK ARE FORECAST TO
FALL TO SLIGHTLY BELOW NORMAL.

.DISCUSSION...
SOUNDINGS THIS MORNING OVER SOUTHERN ARIZONA SHOW THE AIRMASS TO BE
VERY MOIST AND UNSTABLE AT LOW AND MID LEVELS...BUT DRYING ABOVE 550
MB. CAPES FROM SOUNDINGS IN SOUTHERN ARIZONA ARE IN THE 2000 AND
3000 RANGE...WITH LIFTED INDICES WELL INTO THE NEGATIVE. A WEAK
TROUGH MOVING EWD ACROSS NORTHERN ARIZONA WAS RESULTING IN
THUNDERSTORMS OVER COCONINO COUNTY MOVING INTO NAVAJO COUNTY.
ALTHOUGH STEERING WINDS...BEING FROM THE WEST...ARE NOT VERY
FAVORABLE FOR THUNDERSTORMS OVER OUR CWA...THE PRESENCE OF THE VERY
MOIST AND UNSTABLE AIRMASS PRESENTLY OVER THE AREA IS OF SOME
CONCERN. THUS...THE MID SHIFT DID DECIDE TO GO AHEAD AND ADD A
THREAT OF THUNDERSTORMS TODAY FOR THE NORTH PORTION OF THE SOUTH
CENTRAL DESERTS AS WELL AS THE HIGHER TERRAIN OF SOUTH-CENTRAL
ARIZONA. DRIER AIR SUNDAY IS FORECAST TO MOVE IN BEHIND THE
SHORTWAVE TROUGH MOVING EASTWARD ACROSS NORTHERN ARIZONA TODAY. THIS
WILL LESSEN THE CHANCE OF THUNDERSTORM FORMATION.

LOOKING AHEAD...THE PATTERN FOR EARLY NEXT WEEK LOOKS DIFFERENT THAN
IT DID ON MODELS A COUPLE DAYS AGO WHEN WORKING LAST. THE TROUGH
EXPECTED THROUGH THE WESTERN STATES ISNT NEARLY AS DEEP AS MODELS
DEPICTED A FEW DAYS AGO. THUS...THE DRYING THAT WAS FORECAST TO TAKE
PLACE OVER ARIZONA AND SOUTHEAST CALIFORNIA DUE TO A STRONGER
WESTERLY FLOW ALOFT IS NOT NEARLY SO APPARENT. IN FACT...MOISTURE
SEEMS TO INCREASE ESPECIALLY IN SOUTHEAST ARIZONA BY MONDAY FROM A
WEAK LOW PRESSURE AREA...PERHAPS THE REMAINS OF KEVIN. THUS...THE
CHANCE OF THUNDERSTORMS HAD BEEN PUT BACK INTO THE FORECAST FOR
EARLY NEXT WEEK. BERKOVITZ

.PSR...NONE.

AZZ020>028-CAZ030>033-070100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
1135 AM MST SAT SEP 6 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWEST AND
SOUTH-CENTRAL ARIZONA...AND SOUTHEAST CALIFORNIA.

.DAY ONE...TODAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.
HOWEVER...ISOLATED THUNDERSTORMS MAY DEVELOP MAINLY IN NORTH CENTRAL
AND NORTHEAST MARICOPA COUNTY AND OVER THE HIGHER TERRAIN THIS
AFTERNOON...WITH A FEW STRONG STORMS POSSIBLE OVER THE SALT RIVER
LAKES THIS AFTERNOON.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

THE PROBABILITY FOR WIDESPREAD HAZARDOUS WEATHER IS LOW.