Severe Thunderstorm Warning 57, NWS Phoenix, AZ

AZZ020>028-CAZ030>033-261045-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
WEATHER SERVICE PHOENIX AZ
910 PM MST MON AUG 25 2003

.SYNOPSIS...
A FLOW ALOFT FROM THE EAST THEN SOUTH IS EXPECTED THROUGH WEDNESDAY
AS HIGH PRESSURE ALOFT REMAINS CENTERED NORTH AND EAST OF ARIZONA.
IN ADDITION...THERE WILL BE AN INCREASE IN MOISTURE THROUGH
WEDNESDAY FROM THE EAST SIDE OF HURRICANE IGNACIO WHICH WAS IN THE
SOUTHERN GULF OF CALIFORNIA THIS AFTERNOON. THIS MEANS AN INCREASING
CHANCE OF SHOWERS AND THUNDERSTORMS AND COOLER WEATHER. SOME HEAVY
RAIN IS ALSO POSSIBLE. HIGH PRESSURE ALOFT FROM THE PACIFIC IS
EXPECTED TO BRING A REDUCTION IN THUNDERSTORMS BY FRIDAY.

.DISCUSSION...
UPPER HIGH TO REMAIN TO THE NORTH AND EAST OF AZ MAINTAINING A GOOD
MOIST EASTERLY FLOW ACROSS SOUTH CENTRAL AZ INTO SE CA TONIGHT AND
INTO TUES. THIS HAS KEPT AIRMASS OVER THE REGION VERY MOIST TONIGHT
WITH A GOOD COMPLEX OF THUNDERSTORMS OVER FAR W CENTRAL AZ AND FAR
EASTERN CA THIS EVENING PRODUCING HEAVY RAINS AND WAS DRIFTING TO
THE S-SW WITH THE LIGHT FLOW AROUND THE UPPER HIGH. ALTHOUGH THESE
HEAVY RAINY STORMS WERE SLOWLY DECREASING AT THIS TIME AND IT LOOKS
LIKE THE FLASH FLOOD WATCH MAY BE CANCELLED AT 05Z WITH THE FURTHER
DECREASE IN THE STORMS.  OTHER THUNDERSTORMS HAVE AND SHOULD
CONTINUE OVERNIGHT OVER THE ENTIRE REGION. HRCN IGNACIO OVER
SOUTHERN BAJA THIS EVENING IS NOW EXPECTED TO REMAIN OVER BAJA AND
WEAKEN AS IT MOVES UP THE PENNISULA THEN TO ENTER THE PACIFIC NEAR
THE BAJA SPUR. MOISTURE IS EXPECTED TO SPIN OFF THE EASTERN SIDE OF
IGNACIO AND SPREAD INTO SOUTHERN AZ AND SE CA TUES AS THE LOW LEVEL
FLOW CHANGES FROM EASTERLY TO SOUTHERLY LATE TUES. THIS WILL FURTHER
ENRICH THE ALREADY MOIST AIRMASS OVER THE REGION AND INCREASE THE
PROBABILITY FOR SHOWERS AND THUNDERSTORMS ACROSS THE REGION TUES
NIGHT THROUGH WED NIGHT. HEAVY RAINS WILL BE POSSIBLE ESPECIALLY
OVER SOUTH CENTRAL AZ WITHIN THIS MOISTURE RICH ENVIRONMENT. THIS
HANDLED WELL IN CURRENT FORECAST. NO UPDATES. DKS

.PSR...FLASH FLOOD WATCH FOR SOUTHEAST CALIFORNIA ZONES 30...31...
       32...AND 33...EASTERN RIVERSIDE COUNTY AND IMPERIAL COUNTY
       INCLUDING ALL OF JOSHUA TREE NATIONAL PARK UNTIL MIDNIGHT
       PDT OR 26/0700 GMT...MAY BE CANCELLED AT 05Z.

AZZ020>028-CAZ030>033-260100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
600 AM MST MON AUG 25 2003

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

.DAY ONE...TODAY

THE AIRMASS OVER ARIZONA AND SOUTHEAST CALIFORNIA REMAINS VERY MOIST
AND RATHER UNSTABLE. THUS ISOLATED TO SCATTERED THUNDERSTORMS ARE
FORECAST TODAY...MAINLY IN THE LATE AFTERNOON AND EVENING AND MOST
NUMEROUS OVER SOUTH-CENTRAL ARIZONA. WHERE STORMS FORM...LOCALLY
HEAVY RAINFALL COULD OCCUR WHICH MIGHT LEAD TO FLOODING OF WASHES...
ROADWAY DIPS AND OTHER LOW SPOTS. GUSTY DAMAGING WINDS ARE ALSO
POSSIBLE WITH ANY STORMS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THERE WILL BE AN INCREASED POTENTIAL FOR SHOWERS AND THUNDERSTORMS
WITH HEAVY RAIN TUESDAY INTO WEDNESDAY AS MOISTURE FROM HURRICANE
IGNACIO MOVES NORTH AND INTO SOUTHEAST CALIFORNIA...SOUTHWEST AND
SOUTH-CENTRAL ARIZONA. STAY AWAY FROM FLOODED AREAS INCLUDING
ROADWAYS AND WASHES...AND BE PREPARED TO MOVE TO HIGHER GROUND
SHOULD A WARNING BE ISSUED.

.INSTRUCTIONS TO SPOTTERS...
WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.

BRECKENRIDGE

AZZ020>028-CAZ030>033-261300-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PHOENIX AZ
617 PM MST MON AUG 25 2003

...INCREASING PROBABILITY OF HEAVY RAIN AND FLASH FLOOD POTENTIAL
IN SOUTHEAST CALIFORNIA...SOUTHWEST AND SOUTH-CENTRAL ARIZONA
THIS WEEK...

HURRICANE IGNACIO CONTINUES TO MOVE NORTH ALONG THE GULF COAST OF
THE SOUTHERN TIP OF BAJA. THE HURRICANE IS EXPECTED TO MOVE NORTH
OVER BAJA ITSELF...WEAKENING AND THEN ENTER THE PACIFIC NEAR THE
BAJA SPUR BY LATE IN THE WEEK. MOISTURE SPINNING OFF FROM HURRICANE
IGNACIO WILL MOVE INTO SOUTHEAST CALIFORNIA...SOUTHWEST AND
SOUTH-CENTRAL ARIZONA BEGINNING TUESDAY.

THIS WILL ADD MOISTURE TO THE ALREADY MOIST AIRMASS OVER SOUTHEAST
CALIFORNIA...SOUTHWEST AND SOUTH CENTRAL ARIZONA. THIS WILL RESULT
IN A HIGHER PROBABILITIES FOR SHOWERS AND THUNDERSTORMS WITH HEAVY
RAIN AND FLASH FLOODING ESPECIALLY OVER SOUTH CENTRAL ARIZONA
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. YOU ARE URGED TO CHECK THE
LATEST FORECASTS...STATEMENTS...WATCHES AND WARNINGS THIS WEEK.

STAY AWAY FROM FLOODED AREAS INCLUDING FLOODED ROADS...ESPECIALLY AT
NIGHT. BE READY TO MOVE TO HIGHER GROUND IF A WARNING IS ISSUED THIS
WEEK. IF YOU OBSERVE FLOODING...MOVE TO HIGHER GROUND IMMEDIATELY...
DO NOT WAIT FOR A WARNING TO BE ISSUED.

WEATHER INFORMATION IS AVAILABLE ON THE INTERNET AT

WWW.WRH.NOAA.GOV/PHOENIX

OR WEATHER RADIO ON THE PUBLIC SERVICE BAND.

DKS