Flash Flood in Arizona, August 3, 2002

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
240 PM MST SAT AUG 3 2002

.SYNOPSIS...HIGH PRESSURE CENTERED OVER TEXAS WILL PROVIDE A MOIST
SOUTHERLY FLOW THIS WEEKEND...INCREASING THE THREAT THAT SCATTERED
THUNDERSTORM ACTIVITY WILL PRODUCE HEAVY DOWNPOURS. HIGH PRESSURE
WILL THEN CONTINUE TO BUILD INTO THE CENTRAL UNTIED STATES THROUGH
NEXT WEEK...RESULTING IN A MORE FAVORABLE MONSOON FLOW PATTERN FOR
MOST OF SOUTHEASTERN ARIZONA. DRIER SOUTHWEST FLOW WILL MAKE ITS WAY
INTO TO THE WESTERN DESERTS...REDUCING THUNDERSTORM ACTIVITY THERE.

.DISCUSSION...A VERY ACTIVE EARLY AFTERNOON ACROSS SOUTHEASTERN
ARIZONA AS STRONG THUNDERSTORMS WITH VERY HEAVY DOWNPOURS DEVELOPED.
MOST OF THE STORMS HAVE HAD NO TROUBLE PRODUCING RAINFALL RATES OF
OVER .5 OF AN INCH IN 30 MINUTES...SO FLASH FLOODING HAS BEEN THE
MAIN THREAT THIS AFTERNOON. IT LOOKS LIKE MOST OF THE ACTIVITY WAS
BECOMING MORE OR LESS STRATIFORM TYPE RAINFALL...EXCEPT FOR AREAS
GENERALLY WEST OF TUCSON. WOULD EXPECT WIDESPREAD LIGHT TO MODERATE
RAIN WITH A FEW EMBEDDED THUNDERSTORMS TO CONTINUE ACROSS SOUTHERN
ARIZONA THROUGH EARLY THIS EVENING. THE MAIN CONCERN FOR LATER
TONIGHT WILL BE A SECOND WAVE OF SHOWERS AND A FEW THUNDERSTORMS
WITH HEAVY RAIN DEVELOPING SOMETIME AFTER MIDNIGHT OR CLOSER TO
SUNRISE. A SHORTWAVE SOUTH OF ARIZONA WAS NEAR OF THE BAJA SPUR AND
BASED ON ITS CURRENT SPEED SHOULD APPROACH THE NORTHERN GULF OF
CALIFORNIA AFTER MIDNIGHT TONIGHT. THIS FEATURE COULD HELP TRIGGER
SOME MORE WIDESPREAD RAINFALL WITH ISOLATED THUNDERSTORMS BY
TOMORROW MORNING. THINK THE POTENTIAL FOR STRONG THUNDERSTORMS WILL
BE SLIM SINCE THE AIRMASS HAS ALREADY BEEN WORKED OVER THIS
AFTERNOON. HOWEVER...COULD STILL SEE SOME HEAVY RAINFALL OVERNIGHT.
WHAT HAPPENS TOMORROW WILL DEPEND ON WHETHER ADDITIONAL SHOWERS
DEVELOP OVERNIGHT AND THE AMOUNT OF DEBRIS CLOUDINESS WHICH COMBINED
WITH THE A RAIN COOLED BOUNDARY LAYER WOULD LIMIT THE T-STORM
ACTIVITY SUNDAY AFTERNOON AND EVENING. OTHERWISE...THE GENERAL LARGE
SCALE PATTERN REMAINS FAVORABLE FOR SCATTERED T-STORMS THROUGH THE
PERIOD.

.TWC...NONE.

AZZ019-029>035-040700-

SOUTHEAST ARIZONA HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1155 AM MST SAT AUG 3 2002

.SYNOPSIS...AIRMASS OVER SOUTHERN ARIZONA REMAINS VERY MOIST...WITH
ENOUGH INSTABILITY FOR SCATTERED...SLOW MOVING THUNDERSTORMS WITH
HEAVY RAINFALL THIS AFTERNOON.

.DISCUSSION...SCATTERED THUNDERSTORMS HAVE ALREADY DEVELOPED OVER
THE HIGHER TERRAIN OF SOUTHEAST ARIZONA...WITH RAINFALL AMOUNTS
EXCEEDING 1 INCH AN HOUR IN ISOLATED MOUNTAIN LOCATIONS.  AN
INCREASE IN THUNDERSTORM COVERAGE IS EXPECTED DURING THE AFTERNOON
AND INTO THE EVENING HOURS...AIDED BY A SHORTWAVE NOW OVER CENTRAL
BAJA MOVING NORTHWARD AND AFFECTING SOUTHCENTRAL ARIZONA THIS
EVENING.  WINDS ARE LIGHT IN LOWER/MIDDLE TROPOSPHERE...SO EXPECT
STORMS TO BE SLOW MOVING WITH THE PRIMARY THREAT EXCESSIVE RAINFALL
THIS AFTERNOON.  ACCOMPANYING GRAPHICS WILL SHOW THE GREATEST THREAT
FOR MORE THAN ONE INCH OF PRECIPITATION CENTERED OVER SANTA CRUZ
COUNTY.  FREEZING LEVELS ARE RELATIVELY HIGH...AND CLOUD COVER WILL
KEEP DCAPE FROM BECOMING LARGE THIS AFTERNOON.  THUS...HEAVY
RAINFALL THREAT MORE SIGNIFICANT THAN SEVERE THREAT REMAINDER OF
TODAY.

STORM MOTION WILL BE SLOW...AROUND 5 TO 10 MPH...AND GENERALLY TO
THE NORTH.

DRB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TUCSON ARIZONA
0227 PM MST SAT AUG 3 2002

TIME (MST) .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0217 PM    TUCSON                    AZ   76 MPH TSTM WIND GUST
08/03/02   PIMA                           MEASURED BY SPOTTER IN
                                          SOUTH TUCSON