000 
FXUS65 KPSR 060442
AFDPSR
AZZ020>028-CAZ030>033-061045-

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
940 PM MST SAT FEB 5 2005

SOUTHWEST AND SOUTH-CENTRAL ARIZONA...AND SOUTHEAST CALIFORNIA 
FORECAST DISCUSSION

.SYNOPSIS...
A LOW PRESSURE SYSTEM MOVING NORTHEAST ACROSS NORTHWEST MEXICO WILL 
SEND ENOUGH MOISTURE EAST OF THE GREATER PHOENIX AREA FOR A CHANCE 
OF SHOWERS AND THUNDERSTORMS THERE THROUGH THIS EVENING. A LOW 
PRESSURE SYSTEM FROM THE NORTHWEST WILL BRING A SLIGHT CHANCE OF 
SHOWERS TO SOUTH-CENTRAL ARIZONA MAINLY OVER THE HIGHER TERRAIN NORTH
AND EAST OF PHOENIX SUNDAY NIGHT. OTHERWISE...DRY AND COOL WEATHER IS
EXPECTED THIS COMING WEEK AS WEAK HIGH PRESSURE FROM THE PACIFIC 
MOVES OVER THE SOUTHWESTERN UNITED STATES. ANOTHER PACIFIC LOW 
PRESSURE SYSTEM IS EXPECTED TO DEVELOP NEAR THE BAJA CALIFORNIA COAST
SENDING MORE CLOUDS OVER OUR AREA BEGINNING LATE THURSDAY OR FRIDAY.

&&

.DISCUSSION...
BROAD UPPER LEVEL LOW PRESSURE TROF IS NOW SITUATED OVER THE WESTERN 
STATES...AND THE 00Z PLOT DATA SHOWED THIS...AS WELL AS 30M-5OM 
HEIGHT FALLS OVER MOST OF THE SWRN UNITED STATES. SERIES OF IMPULSES 
ARE MOVING THRU THE MEAN TROF...AND ONE SUCH LOW IS NOW OVER FAR ERN 
AZ AND MOVING INTO NM. THIS SYSTEM WHICH EARLIER HAD A CLOSED LOW 
CENTER OVER NCNTRL BAJA HAS LIFTED NEWD...AND THE AIRMASS OVER ERN 
BECAME A BIT MORE UNSTABLE AS SOME COLDER AIR ALOFT FILTERED IN. THO 
NO THUNDERSTORMS DEVELOPED IN OUR CWA THIS AFTN/EVE...A FEW SHOWERS 
DID OCCUR OVER ZONE 24...AND EVEN IN THE ERN PORTIONS OF ZONE 23. AS 
OF 9 PM THE SHOWERS HAD MOSTLY DISSIPATED AND SKIES WERE PARTLY TO 
MOSTLY CLOUDY. THE CLOUDS OVERHEAD THIS EVE WERE A MIX OF THE MID 
CLOUDS ASSOCD WITH THE EXITING TROF...AND A BAND OF MAINLY HIGH 
CLOUDS SPREADING INTO OUR WRN CWA AHEAD OF THE NEXT APPROCHING 
SHORTWAVE. EARLIER HAD AMENDED THE ZONES TO ADD A FEW EVE SPRINKLES 
INTO THE PHOENIX AREA AS WELL AS INTO ERN ZONE 28...BUT BY MIDNIGHT 
SHOWERS SHOULD BE OVER WITH JUST PARTLY CLOUDY SKIES REMAINING MOST 
PLACES.

PROGS CONTINUE TO FORECAST ANOTHER SERIES OF FAST MOVING WAVES TO 
MOVE THRU THE STATE SUNDAY NIGHT THRU MONDAY EVENING...AND THEY 
SHOULD MAINLY AFFECT THE NORTHERN PORTION OF THE STATE...WITH THE 
BEST THREAT FOR SHOWERS IN THE CENTRAL DESERTS TO BE NORTH AND 
EAST OF CENTRAL PHOENIX DURING THE SUNDAY NIGHT PERIOD. THIS ALREADY 
IN THE FORECAST AND THIS LOOKS PRETTY GOOD. MODELS HAVE BEEN 
WAFFLING BACK AND FORTH REGARDING STRENGTH AND MOISTURE AVAILABILITY 
WITH THE SUN NIGHT/MONDAY STORM...AND THE ETA/GFS HAVE FLIPPED 
FLOPPED REGARDING WHICH WILL BE THE DEEPER OR WETTER RUN. NOW THE 
GFS SEEMS TO BE THE DEEPER AND WETTER OF THE TWO...AND WITH THE 
INCONSISTENCY THE FORECAST IS SORT OF A BLEND BETWEEN THE TWO. 
LATEST MET GUIDANCE HAS A 6 PERCENT POP FOR PHOENIX ON SUNDAY NIGHT 
VERSUS 30 PERCENT FROM THE MAV. CURRENT FORECAST CALLS FOR AROUND A 
10 PERCENT CHANCE...WITH CHANCES INCREASING THE FURTHER NORTH YOU GO 
FROM CENTRAL PHOENIX. OVERALL FORECAST TRENDS SEEM PRETTY GOOD AND 
NO MORE CHANGES ARE PLANNED ON THIS SHIFT.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE. 

&&

$$

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