Flash Flood in Arizona, August 24, 2003

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
900 PM MST SUN AUG 24 2003

.SYNOPSIS...INCREASING MOISTURE ASSOCIATED WITH HURRICANE IGNACIO
WILL TRACK NORTH TOWARD THE DESERT SOUTHWEST EARLY THIS WEEK. THIS
INFLUX IN MOISTURE SHOULD LEAD TO AN UPSWING IN RAINFALL
COVERAGE...ESPECIALLY TUESDAY INTO WEDNESDAY.

.DISCUSSION...BUSY AFTERNOON AND EVENING FOR CONVECTION WITH STORMS
STILL HOLDING ON. THIS UNDER THE SEASONAL AUSPICES OF HIGH PRESSURE
ANCHORED TO OUR NORTHEAST AND MOISTURE FILTERING IN FROM MEXICO.
BORDER AREAS WITH NEW MEXICO DOWN A BIT COVERAGE-WISE COMPARED TO
THE REST OF THE AREA WITH PRECIPITABLE WATER VALUES CLOSER TO AN
INCH AND SURFACE DEWPTS IN THE 50S (COMPARED TO A 1.3 TO 1.5 INCH
RANGE FURTHER WEST WITH DEWPTS IN THE 60S).

MOST SIGNIFICANT WEATHER FEATURE IS SHAPING UP TO BE HURRICANE
IGNACIO. CURRENTLY AT THE MOUTH OF THE GULF OF CALIFORNIA...OFFICIAL
TRACK BRINGS HIM SLOWLY UP THE GULF TO AROUND 28N BY THE END OF THE
WEEK AS IT WEAKENS. BEFORE THIS HAPPENS THOUGH...WE WILL HAVE TO
DEAL WITH TWO THINGS. FIRST...A TROPICAL SYSTEM WITH THIS POSITION
AND TRAJECTORY TYPICALLY PUSHES A LOT OF MOISTURE AHEAD OF IT INTO
ARIZONA. SECONDLY...THE POSITION OF THE TROPICAL SYSTEM WILL LEAD TO
UPPER LEVEL CONDITIONS IDEAL FOR WIDESPREAD ORGANIZED CONVECTION BY
LATE TUESDAY OR WEDNESDAY. SHOULD BE QUITE A BIT COOLER AS WELL. WE
MAY NEED TO PUNCH UP POPS A BIT FOR THAT TIME PERIOD...OTHERWISE WE
HAVE THE RIGHT GENERAL TRENDS. M

.TWC...NONE.

AZZ019-029>035-251400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1155 AM MST SUN AUG 24 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

SYNOPSIS...ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED TO DEVELOP
LATE THIS AFTERNOON AND EVENING AS ABUNDANT MOISTURE IS IN PLACE.
LAST NIGHTS THUNDERSTORMS MAY SLOW THE DEVELOPMENT OF STORMS TODAY
BUT THIS EVENING THUNDERSTORMS SHOULD BE ABLE TO MOVE INTO VALLEYS.

DISCUSSION...THUNDERSTORMS WORKED OVER THE LOWER DESERTS LAST NIGHT
WHICH IS USUALLY PROHIBITIVE FOR THUNDERSTORMS IN THE VALLEYS THIS
AFTERNOON...AND BELIEVE THIS SCENARIO IS CORRECT FROM TUCSON WEST.
TO THE EAST...THUNDERSTORMS SHOULD BE ABLE TO DEVELOP ON THE
MOUNTAINS AND MOVE INTO THE VALLEYS. THE EAST HAS BEEN INHIBITED BY
LOWER MOISTURE VALUES THE LAST FEW DAYS BUT SATELLITE PRECIPITABLE
WATER AND THE EL PASO SOUNDING SHOWS MORE MOISTURE IN PLACE AND
ACTIVITY SHOULD FORM ON THE MOUNTAINS MOVE INTO THE VALLEYS IN THESE
LOCATIONS THIS AFTERNOON. SOUNDING DOES SHOW THAT STORMS WILL HAVE A
HARD TIME GETTING PAST INVERSION AT 400 MB INITIALLY SO LATE START
TO STORMS SEEMS LIKELY. THIS EVENING EASTERN STORMS SHOULD BE ABLE
TO PROPAGATE INTO TUCSON AND WEST ON FAVORABLE MID LEVEL FLOW USING
MID LEVEL CAPE.

THE CHANCE OF SEVERE THUNDERSTORMS AND ONE INCH RAIN REMAINS NEAR
CLIMATOLOGY. THE MOVEMENT OF THE STORMS WILL BE WEST AT 10 TO 15
MPH.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

MODELS INDICATE THAT MONDAY AFTERNOON SHOULD SEE A MORE ORGANIZED
THUNDERSTORM EVENT ACROSS SOUTHEAST ARIZONA. IN ADDITION...MOISTURE
FROM HURRICANE IGNACIO...WHICH WILL MOVE NORTH ALONG THE BAJA COAST
EARLY THIS WEEK AND KEEP A VERY MOIST ATMOSPHERE IN PLACE ACROSS
SOUTHEAST ARIZONA DURING THE WEEK.  A DRIER SOUTHWEST FLOW ALOFT
WILL DEVELOP ACROSS THE DESERT SOUTHWEST OVER THE WEEKEND.

.SPOTTER INFORMATION STATEMENT...

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