000 
FXUS65 KPSR 071014
AFDPSR
AZZ020>028-CAZ030>033-071745-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
314 AM MST WED MAR 7 2001

.SYNOPSIS...
AN INTENSE LOW PRESSURE SYSTEM MOVED OVER SOUTHERN CALIFORNIA AND 
NORTHERN BAJA THIS MORNING. IT IS EXPECTED TO MOVE OVER SOUTHEAST 
CALIFORNIA THIS MORNING AND THEN CROSS SOUTHWEST AND SOUTH-CENTRAL 
ARIZONA DURING THE DAY. SHOWERS AND ISOLATED THUNDERSTORMS WILL BE 
ACCOMPANYING THIS SYSTEM...WITH GRADUALLY IMPROVING WEATHER ON ITS 
WEST SIDE. DRIER...SOMEWHAT WARMER WEATHER WILL MOVE IN AS HIGHER 
PRESSURE REPLACES THE EXITING LOW. HOWEVER...ANOTHER PACIFIC STORM 
SYSTEM WILL BRING COOLER...WET WEATHER TO SOUTHEAST CALIFORNIA AND 
SOUTHWEST AND SOUTH-CENTRAL ARIZONA OVER THE WEEKEND.

.DISCUSSION...
STRONG UPPER LOW HAS BEEN MOVING EWD THIS MORNING AND IS OVER FAR 
SRN CA. DIFLUENT FLOW PRECEDING THE LOW...COUPLED WITH JET DYNAMICS 
AND PLENTY OF MOISTURE BROUGHT SHOWERS AND THUNDERSTORMS TO MUCH OF 
THE PHX CWA LAST EVE AND THIS MORNING. SYSTEM HAS BEEN AN EFFICIENT 
PRECIPITATION PRODUCER AND URBAN AND SMALL STREAM FLOOD ADVISORIES 
CONTINUE IN EFFECT THROUGH THIS MORNING IN SW AZ AND ALONG THE LWR 
CO RIVER VALLEY S OF PARKER. IN ADDITION...A FLASH FLOOD WATCH WILL 
REMAIN IN EFFECT FOR NRN MARICOPA COUNTY...NW PINAL COUNTY AND SRN 
GILA COUNTY UNTIL 100 PM THIS AFTERNOON. OVER AN INCH AND A HALF OF 
RAIN HAS FALLEN IN THE YUMA AREA...AND SIMILAR AMOUNTS ARE NOT OUT 
OF THE QUESTION IN THE FLASH FLOOD WATCH AREA. THUNDERSTORMS ARE 
EXPECTED TO INCREASE DURING THE DAY...ESPECIALLY OVER THE CENTRAL 
AND ERN PORTIONS OF THE PHX CWA...WITH HAIL A DEFINITE POSSIBILITY 
AS WET-BULB ZERO LEVELS DROP BELOW 7K FT. EVEN LOW-TOP STORMS WILL 
BE CAPABLE HAIL PRODUCERS. AS MENTIONED BY THE SWING SHIFT FCSTR...
00Z H5 AND H3 PLOT DATA SHOWED A VERY STRONG DIFLUENT AND DYNAMICAL 
SIGNATURE OVER OUR WRN CWA. THIS IS EXPECTED TO BECOME ENHANCED AS 
IT MOVES OVER S-CENTRAL AZ THIS MORNING. IN ADDITION...SYSTEM HAS A 
GOOD FLOW OF LOW LEVEL MOISTURE INTO IT AND P-WATER VALUES COMING 
INTO SRN AZ AHEAD OF THE SYSTEM ARE GREATER THAN THREE QUARTERS OF 
AN INCH IN SPOTS. AVN MODEL...WHICH APPEARED TO BE INITIALIZED WELL 
...SLOWLY MOVES THE LOW ACROSS S-CENTRAL AZ THIS AFTERNOON...WITH 
THE STRONG DYNAMICS DIMINISHING SOMEWHAT LATE IN THE DAY. MADE SOME 
MINOR CHANGES TO THE FORECAST BASED ON CURRENT TRENDS...BUT GENERAL 
FORECAST STILL LOOKS GOOD. NO CHANGES MADE TO THE EXTENDED FORECAST. 

FLASH FLOOD WATCH IN EFFECT UNTIL 100 PM MST FOR NRN MARICOPA...NW 
PINAL AND SRN GILA COUNTIES. URBAN AND SMALL STREAM FLOOD ADVISORY 
IN EFFECT UNTIL 800 AM MST/700 AM PST FOR THE LOWER CO RIVER S OF 
PARKER...AND PORTIONS OF SW AZ.  WILT