000 
FXUS65 KPSR 191757
AFDPSR

AZZ020>028-CAZ030>033-192245-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1056 AM MST FRI JAN 19 2001

.SYNOPSIS...
HIGH PRESSURE OVER SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA WILL 
BRING A WARMING TREND THROUGH THIS WEEKEND. HOWEVER...THE FIRST IN A 
SERIES OF WEATHER DISTURBANCES WILL BRING MAINLY HIGH CLOUDS TO THE 
REGION TONIGHT AND SATURDAY. HIGH PRESSURE WILL RECOVER SUNDAY FOR 
MOSTLY CLEAR SKIES. A STRONGER DISTURBANCE WILL BRING SIGNIFICANT 
COOLING AND A CHANCE OF SHOWERS OR A THUNDERSTORM TO THE REGION AS 
IT MOVES ACROSS SOUTHERN CALIFORNIA AND ARIZONA MONDAY AND TUESDAY. 
YET ANOTHER LOW PRESSURE SYSTEM IS EXPECTED TO MOVE IN FROM THE 
PACIFIC AROUND THURSDAY FOR CONTINUED UNSETTLED WEATHER.

.DISCUSSION...
THE FIRST IN A SERIES OF WEATHER DISTURBANCES WILL BEGIN MOVING 
ACROSS NRN AZ TODAY..FOR INCREASING MAINLY MID AND HIGH LVL CLDS 
TONIGHT...AND PARTLY CLOUDY EARLY SAT. THIS SYSTEM WILL QUICKLY PASS 
TO THE EAST FOR DECREASING CLOUDS SAT AFTERNOON. THE RIDGE IS 
EXPECTED TO RECOVER ON SUN FOR MOSTLY CLEAR TO PARTLY CLOUDY SKIES. 
THE MODELS SEEM TO BE COMING TOGETHER WITH THE TIMING AND INTENSITY 
OF THE SECOND WEATHER DISTURBANCE. THIS SECOND SYSTEM WILL BE 
CONSIDERABLY STRONGER THAN THE FIRST...WITH THE UPR LOW MOVING 
ONSHORE OVER CENTRAL CA MON. WILL KEEP A CHANCE FOR SHOWERS AND 
POSSIBLE TSTORMS OVR SOUTHEAST CALIFORNIA LATE MON NIGHT. INCREASING 
CLDS AND SIGNIFICANTLY COOLER TEMPS WILL SPREAD INTO THE GREATER 
PHOENIX AREA ON TUES FOR A CHANCE OF SHOWERS AND THUNDERSTORMS OVER 
THE SOUTH-CENTRAL DESERTS. THICKNESS LVLS WITH THIS SYSTEM INDICATE 
THE SNOW LVL COULD DROP TO AROUND 4000 FEET MON NIGHT AND TUE 
MORNING. MODELS POINT TO WED BEING ANOTHER IN BETWEEN DAY...WITH THE 
CHANCE FOR SHOWERS AND TSTORMS AGAIN ON THU AS THE THIRD WEATHER 
SYSTEM BEGINS MOVING OVER THE REGION. WILL LIKELY INTRODUCE THE 
CHANCE FOR SHOWERS FOR OUR ENTIRE CWA ON THU. FOR NOW...NO UPDATES 
NEEDED. LW