Severe Thunderstorm Warning 15, NWS Phoenix, AZ

AZZ020>028-CAZ030>033-050545-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
300 PM MST SAT AUG 4 2001

.SYNOPSIS...
STRONG HIGH PRESSURE OVER THE CENTRAL UNITED STATES WILL MOVE WEST
AND BE CENTERED OVER WYOMING EARLY NEXT WEEK. THE FLOW AROUND THIS
SYSTEM...COUPLED WITH ABUNDANT MOISTURE...WILL RESULT IN AFTERNOON
AND NIGHTTIME THUNDERSTORMS OVER SOUTH-CENTRAL ARIZONA AND PART OF
SOUTHWEST ARIZONA THROUGH THE MIDDLE OF NEXT WEEK. THERE WILL BE A
SLIGHT CHANCE OF STORMS IN SOUTHEAST CALIFORNIA SUNDAY AND SUNDAY
NIGHT...BEFORE SOME DRIER AIR BEGINS TO PUSH IN FROM THE WEST ONCE
AGAIN.

.DISCUSSION...
RAISED POPS IN PART OF S-CNTRL AZ FOR TONIGHT IN DEFERENCE TO THE
INCREASED POTENTIAL FOR STORMS. THE MOISTURE GRADIENT IS QUITE TIGHT
ACROSS S-CNTRL AZ. DRIER AIR HAS INTRUDED FROM THE W AND IS BUTTING
UP AGAINST THE MOIST AIR IN PLACE OVER CNTRL AND ERN AZ...NOT TOO
FAR W OF THE PHX METRO AREA. DEWPOINT AT GILA BEND WAS 41 DEG AT 21Z
...WITH LOW TO MID 60S JUST E OF THERE. MOISTURE EXPECTED TO SLOWLY
PUSH BACK WWD TONIGHT AS FLOW IS CHANGING FROM SLY TO MORE ELY OVER
SRN AZ. WE WILL HAVE TO WATCH STORMS FROM THE S AND SE...AS WELL AS
ANY BACK-BUILDING STORMS ALONG THE NRN BORDER OF THE CWA. THE SEVERE
POTENTIAL IS HIGHER TODAY THAN RECENTLY...WITH STRONG WIND THE MAIN
THREAT...WITH A SECONDARY THREAT OF HEAVY RAINFALL AND SLOW-MOVING
STORMS. WILL HAVE TO WATCH FOR FFW POSSIBILITIES AS WELL. HEAVY RNFL
JUST N OF OUR CWA MAY LEAD TO HEAVY RUNOFF INTO OUR CWA...SO THAT IS
A CONCERN AS WELL AND WILL HAVE TO BE MONITORED. ALSO...THERE WILL
BE A NUMBER OF OUTFLOW BOUNDARY INTERACTIONS IN THE CNTRL AND ERN
PORTIONS OF THE CWA THIS EVENING...LIKELY ENHANCING SEVERE POTENTIAL
AS WELL AS LEADING TO A THREAT OF BLOWING DIUST. EXPECT A RUN-OF-THE
-MILL CONVECTIVE DAY THIS AREA TOMORROW...HOWEVER...DO LOOK FOR A
POSSIBILITY OF ISOLATED STORMS FINALLY GETTING INTO FAR WRN PORTIONS
OF THE CWA AS A WEAKENING INVERTED TROUGH MOVES ACROSS NRN MEX AND
BRUSHES THAT AREA. IN THE EXTENDED...WILL KEEP A CHANCE OF STORMS
INTO THU MOST AREAS OF S-CNTRL AZ...THRU SAT HIGHER TERRAIN. DRIER
AIR COMING IN TO SLOW THINGS DOWN AGAIN FRI AND SAT AS ANOTHER ERN
PAC TROUGH MAKES ITS PRESENCE FELT BY TURNING THE FLOW SWLY OVER A
GOODLY PORTION OF THE CWA AND PROVIDING SOME COOLING AS THE HEIGHTS
COME DOWN]. WILL KEEP A CHANCE OF STORMS GOING IN THE HIGHER TERRAIN
OF ZONE 24 THRU THE EXTENDED...AS MOISTURE WILL LINGER THERE.  WILT