000 
FXUS65 KPSR 010939
AFDPSR

AZZ020>028-CAZ030>033-011745-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
237 AM MST SUN JUL 1 2001

.SYNOPSIS...
A LARGE HIGH PRESSURE SYSTEM ALOFT...CENTERED OVER THE FOUR CORNERS
REGION...WILL DRIFT SLOWLY NORTHWARD THIS WEEK. THIS WILL CHANGE THE 
FLOW PATTERN OVER SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA SO THAT 
SOUTHEAST WINDS WILL BRING IN HIGHER DEWPOINTS AND GREATER RELATIVE 
HUMIDITY. ALONG WITH THIS MOISTURE INCREASE WILL COME AN INCREASING  
THREAT OF THUNDERSTORMS...INITIALLY IN SOUTH-CENTRAL ARIZONA AND THE 
NORTHERN PORTION OF THE BAJA PENINSULA...BUT SPREADING OVER THE REST 
OF THE REGION TUESDAY THROUGH THE END OF THE WEEK. DESERT STORMS ARE 
EXPECTED TO PRODUCE STRONG...GUSTY WIND AND BLOWING DUST OR SAND.

.DISCUSSION...
CONTAMINATED PSR 00Z SOUNDING...WAY TOO MOIST...MADE IT INTO THE 00Z 
MODEL RUNS. THEREFORE...MOST MODEL DATA TO BE TAKEN WITH A GRAIN OF 
SALT FOR THIS REGION. LOOK FOR A GRADUAL UPRAMPING OF TSTM ACTIVITY 
THE NEXT FEW DAYS...WITH A BIG INCREASE IN ACTION WED THRU THE END 
OF THE WEEK. THIS DUE TO THE NWD MOVEMENT OF THE 4 CORNERS HIGH AND 
A DEVELOPING FETCH OF MOIST...UNSTABLE AIR ACROSS THE REGION. CAPE 
HAS BEEN SPARSE LATELY...WITH NOTHING MUCH GOING ON TO RELEASE WHAT 
THERE HAS BEEN. THIS WILL CHANGE GRADUALLY AS MOISTURE INCREASES AND 
PERTURBATIONS IN THE FLOW ROTATE ACROSS THE AREA TO ACT AS TRIGGERS. 
DEWPOINTS INCREASING ON THE DESERTS...WITH SOME OUTFLOW FROM TSTMS 
OVER MEXICO AIDING IN THIS INCREASE. IN ADDITION...LOOK FOR DEBRIS 
CLOUDINESS TO MOVE OVER GULF OF CA...KEEPING IT RELATIVELY COOL... 
WHILE THE LOWER DESERTS OF SW AZ AND SE CA HEAT UP TO AT LEAST WHERE 
THEY WERE YESTERDAY. THIS WILL SERVE TO DRAW SOME MOISTURE UP FROM 
THE GULF...KEEPING THE DESERT DEWPOINTS IN THE 50S. NO MAJOR CHANGES 
TO BE MADE IN THE EXISTING FORECAST AT THIS TIME.  WILT