Flash Flood Warning 9, NWS Phoenix, AZ

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
950 AM MST MON AUG 30 1999

.SYNOPSIS...
HIGH PRESSURE OVER NEW MEXICO AND LOW PRESSURE ALONG THE WEST COAST
WILL KEEP SOUTHERLY WINDS ALOFT OVER OUR AREA. THERE WILL ALSO BE
SEVERAL WEAK IMPULSES THAT WILL DRIFT INTO ARIZONA THROUGH TUESDAY
THAT WILL HELP INCREASE THE THREAT OF SHOWERS AND THUNDERSTORMS.
BY LATE IN THE WEEK LOWER HUMIDITY IS EXPECTED ACROSS SOUTHEAST
CALIFORNIA AND MUCH OF SOUTHWEST ARIZONA AS THE FLOW ALOFT SWITCHES
TO A MORE SOUTHWESTERLY DIRECTION.

DISCUSSION...
EXPECTING ANOTHER PRETTY ACTIVE CONVECTIVE DAY/EVENING OVER MOST OF
CWFA...AS VERY MOIST AND UNSTBABLE AIRMASS REMAINS IN PLACE...AS
EVIDENCED BY PWATER OF OVER 2 INCHES AT YUMA AND LI OF MINUS 4.
AND...IF YOU BELIEVE THE ETA VORT PROGS...LOOKS LIKE THERE MAY BE
SOME DYNAMICS TO HELP TRIGGER ACTION AGAIN TODAY DOWN IN SW AZ...
PROBABLY STILL PESKY REMAINS OF BRET. NOT SO SURE SLIGHT CHANCE WILL
COVER THINGS DOWN THERE...SO WILL UP POPS JUST A BIT. MEANWHILE...
FURTHER E...APPEARS AIRMASS NOT QUITE AS SOPPING WET...BUT STILL
CERTAINLY ENOUGH MOISTURE TO FUEL STORMS TODAY. AND...LOOKING AT FAR
WRN CWFA...APPEARS SOME DRIER LOW LEVEL AIR READY TO ADVECT INTO AREA
WITH NXP...TRM AND PSP ALL HAVING DROPPED INTO THE 35 TO 45 DEGREE
DEWPOINT RANGE. WILL OPT TO TAKE OUT STORMS IN JTNP BUT LET FORECASTS
RIDE WITH SLIGHT CHANCES ELSEWHERE IN FAR SE CA. STILL CONCERNED
ABOUT THE POSSIBILITY OF SEVERE MULTICELLS BY TUE OR WED AS WIND
PROFILES BECOME MORE FAVORABLE WITH NEARING TROF AND SOME WEAK
IMPULSES IN THE WLY FLOW BEGIN TO ACT ON MONSOON MOISTURE BOUNDARY.
ANYWAY...TIL THEN LOCALLY HEAVY RAINFALL THE MAIN WEATHER THREAT AND
THIS COVERED IN THE CURRENT FORECASTS. ONLY CHANGES TO ZONES WILL BE
THOSE SLIGHT TWEEKS MENTIONED ABOVE.   ESTLE

AZZ020>028-CAZ031-310600-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
1228 PM MST (1228 PM PDT) MON AUG 30 1999

...LOCALLY HEAVY RAIN POSSIBLE ACROSS SOUTH CENTRAL AND SOUTHWEST
ARIZONA AS WELL AS EXTREME SOUTHEAST CALIFORNIA THIS AFTERNOON AND
EVENING...

A VERY MOIST AND UNSTABLE AIR MASS REMAINS IN PLACE ACROSS SOUTH
CENTRAL AND SOUTHWEST ARIZONA...AS WELL AS FAR SOUTHEAST
CALIFORNIA TODAY. CONSIDERABLE DAYTIME HEATING WILL SERVE TO LIFT
THIS MOISTURE INTO SCATTERED SHOWERS AND THUNDERSTORMS...SOME OF
WHICH COULD PRODUCE VERY HEAVY RAINFALL INTO THIS EVENING. LOCALIZED
AMOUNTS OF BETWEEN ONE AND TWO INCHES PER HOUR ARE POSSIBLE WITH THE
STRONGEST STORMS. ALSO...WIND GUSTS APPROACHING 45 MPH ARE POSSIBLE.

THIS OUTLOOK WILL BE ISSUED ONLY ON DAYS WHEN SOME FORM OF HAZARDOUS
WEATHER IS EXPECTED SOMEWHERE OVER THE PHOENIX AREA OF WARNING
RESPONSIBILITY...WHICH INCLUDES SOUTH-CENTRAL AND SOUTHWEST ARIZONA
AS WELL AS FAR SOUTHEAST CALIFORNIA.

FOR PURPOSES OF THIS OUTLOOK HAZARDOUS WEATHER REFERS TO ANY OF THE
FOLLOWING...LOCALLY HEAVY RAINFALL WHICH RESULTS IN FLOODING AND
RUNNING WASHES...SAND OR DUST STORM WHICH REDUCES VISIBILITY TO ONE
QUARTER MILE OR LESS...DAMAGING WINDS IN EXCESS OF 57 MPH...AND HAIL
AT LEAST THREE QUARTERS OF AN INCH IN DIAMETER.

WHEN HAZARDOUS WEATHER IS IMMINENT OR OCCURRING...THE PHOENIX
NATIONAL WEATHER SERVICE FORECAST OFFICE WILL PROVIDE IMPORTANT LIFE-
SAVING INFORMATION IN THE FORM OF WARNINGS...FOLLOW-UP STATEMENTS...
AND SHORT TERM FORECASTS.

STORM SPOTTER ACTIVATION MAY BE NECESSARY LATER TODAY.

ESTLE