Flash Flood Warning 61, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
940 AM 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 FEW THUNDERSTORMS ALREADY DEVELOPING THIS MORNING
ACROSS WESTERN PIMA COUNTY INTO SANTA CRUZ. THESE STORMS APPEARED TO
BE FORMING ALONG A PRE-EXISTING OUTFLOW BOUNDARY IN THE REGION OF
DRIER AIR ALOFT. A FEW LARGER SCALE FEATURES WERE SHOWING UP NICELY
IN THE WATER VAPOR IMAGERY THIS MORNING. THE FIRST ONE WHICH SHOULD
IMPACT SOUTHERN ARIZONA LATE THIS AFTERNOON AND EVENING WAS A
SHORTWAVE TRACKING NORTH AND APPROACHING CENTRAL BAJA AT THIS TIME.
THE OTHER FEATURE WAS AN UPPER LOW SOUTH OF TEXAS WHICH IS FORECAST
TO TRACK NORTHWEST POSSIBLY AFFECTING OUR WEATHER LATE SUNDAY INTO
TUESDAY. FOR NOW...CURRENT FORECAST LOOKS ON OKAY. UPDATE EARLIER TO
INCREASE POPS OUT WEST.

.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