940 
FXUS65 KPSR 102141
AFDPSR

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
240 PM MST FRI DEC 10 1999

.SYNOPSIS...
UPPER LOW PRESSURE SYSTEM WILL MOVE THROUGH EXTREME SOUTHERN ARIZONA
TONIGHT THROUGH SATURDAY. THIS SYSTEM WILL BRING A CONTINUED CHANCE
FOR SHOWERS OVER MUCH OF SOUTHWEST AND SOUTH CENTRAL ARIZONA TONIGHT
INTO EARLY SATURDAY. SOME SNOW IS POSSIBLE ABOVE 3000 FEET ELEVATIONS
EAST OF PHOENIX TONIGHT. WINDY WEATHER WILL ALSO BE THE RULE AT MANY
DESERT SPOTS LATER TONIGHT INTO SATURDAY BEHIND A SURFACE COLD FRONT.
CLEARING SKIES WILL BE THE RULE ACROSS ALL OF THE AREA ON SATURDAY
WITH SUNNY AND WARMER WEATHER IN STORE FOR SUNDAY THROUGH WEDNESDAY
AS HIGH PRESSURE ALOFT MOVES BACK INTO THE DESERT SOUTHWEST.

.DISCUSSION...
MODELS SEEM TO BE VERIFYING FAIRLY WELL THIS AFTERNOON PER LATEST WV
IMAGERY TRENDS. VORT MAX DIGGING SEWD THROUGH FAR SE CA AND ABOUT TO
HEAD INTO FAR NW MEX. SYSTEM APPEARS AS IF IT IS ALREADY BEGINNING TO
CLOSE OFF. A BIT OF UPPER DIFFLUENCE ALSO APPEARS TO BE DRAPED OVER
SW DESERTS AND GIVING RISE TO SOME TCU OVER SE CA DESERTS. BEST UVV
FIELD STILL EXPECTED TO PASS THROUGH SRN AZ TONIGHT AND THEN INTO SE
AZ LATE. MODEL RH CROSS SECTIONS INDICATING DECENT LAYER OF HIGHER RH
EXPECTED TO BLOSSOM OVER CNTRL/ERN CWFA TONIGHT AND THEN RAPIDLY MOVE
EWD BY EARLY SATURDAY. ALTHOUGH QPFS EXPECTED TO BE SMALL...STILL
EXPECTING ENOUGH TO GIVE SOME ACCUMULATING SNOW TO HIGHER ELEVATIONS
TO E OF PHX...WITH SNOW LEVELS DOWN TO AROUND 3000 FEET. WILL ISSUE
SNOW ADVISORY FOR ZONE 24 TONIGHT/ERLY SAT ABOVE 4000 FEET FOR AN
INCH OR TWO OF SNOW. UPPER LOW MOVES OUT RATHER QUICKLY ON SATURDAY
ESPECIALLY BY THE AVN. SYSTEM WILL PROBABLY BE A BIT SLOWER THAN
THAT...MORE IN LINE WITH ETA/NGM. PROBABLY A MOOT POINT FOR OUR CWFA
AS EVEN THE SLOWEST SOLUTION WOULD ARGUE FOR CLEARING FAR EAST DURING
AFTERNOON. SATURDAY NIGHT WILL BE CLEAR AND COLD WITH FREEZING TEMPS
MOST OUTLYING DESERT AREAS. SUNDAY SHOULD BEGIN THE WARMUP AS HIGH
PRESSURE ALOFT MOVES CLOSER. EXTENDED WILL BE DRY...STARTING OUT WITH
RIDGE ALOFT FOLLOWED BY TROUGHING TO OUR N. THIS TROUGH WILL STAY FAR
ENOUGH TO THE N TO KEEP US DRY BUT WILL PROBABLY BRING HALT TO
WARMUP. PLEASE REFER TO LATEST STATEMENTS FROM PHX NWS OFFICE FOR
DETAILS REGARDING SNOW ADVISORY.  ESTLE

000 
TTAA00 KPHX 102141

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
240 PM MST FRI DEC 10 1999

.SYNOPSIS...
UPPER LOW PRESSURE SYSTEM WILL MOVE THROUGH EXTREME SOUTHERN ARIZONA
TONIGHT THROUGH SATURDAY. THIS SYSTEM WILL BRING A CONTINUED CHANCE
FOR SHOWERS OVER MUCH OF SOUTHWEST AND SOUTH CENTRAL ARIZONA TONIGHT
INTO EARLY SATURDAY. SOME SNOW IS POSSIBLE ABOVE 3000 FEET ELEVATIONS
EAST OF PHOENIX TONIGHT. WINDY WEATHER WILL ALSO BE THE RULE AT MANY
DESERT SPOTS LATER TONIGHT INTO SATURDAY BEHIND A SURFACE COLD FRONT.
CLEARING SKIES WILL BE THE RULE ACROSS ALL OF THE AREA ON SATURDAY
WITH SUNNY AND WARMER WEATHER IN STORE FOR SUNDAY THROUGH WEDNESDAY
AS HIGH PRESSURE ALOFT MOVES BACK INTO THE DESERT SOUTHWEST.

.DISCUSSION...
MODELS SEEM TO BE VERIFYING FAIRLY WELL THIS AFTERNOON PER LATEST WV
IMAGERY TRENDS. VORT MAX DIGGING SEWD THROUGH FAR SE CA AND ABOUT TO
HEAD INTO FAR NW MEX. SYSTEM APPEARS AS IF IT IS ALREADY BEGINNING TO
CLOSE OFF. A BIT OF UPPER DIFFLUENCE ALSO APPEARS TO BE DRAPED OVER
SW DESERTS AND GIVING RISE TO SOME TCU OVER SE CA DESERTS. BEST UVV
FIELD STILL EXPECTED TO PASS THROUGH SRN AZ TONIGHT AND THEN INTO SE
AZ LATE. MODEL RH CROSS SECTIONS INDICATING DECENT LAYER OF HIGHER RH
EXPECTED TO BLOSSOM OVER CNTRL/ERN CWFA TONIGHT AND THEN RAPIDLY MOVE
EWD BY EARLY SATURDAY. ALTHOUGH QPFS EXPECTED TO BE SMALL...STILL
EXPECTING ENOUGH TO GIVE SOME ACCUMULATING SNOW TO HIGHER ELEVATIONS
TO E OF PHX...WITH SNOW LEVELS DOWN TO AROUND 3000 FEET. WILL ISSUE
SNOW ADVISORY FOR ZONE 24 TONIGHT/ERLY SAT ABOVE 4000 FEET FOR AN
INCH OR TWO OF SNOW. UPPER LOW MOVES OUT RATHER QUICKLY ON SATURDAY
ESPECIALLY BY THE AVN. SYSTEM WILL PROBABLY BE A BIT SLOWER THAN
THAT...MORE IN LINE WITH ETA/NGM. PROBABLY A MOOT POINT FOR OUR CWFA
AS EVEN THE SLOWEST SOLUTION WOULD ARGUE FOR CLEARING FAR EAST DURING
AFTERNOON. SATURDAY NIGHT WILL BE CLEAR AND COLD WITH FREEZING TEMPS
MOST OUTLYING DESERT AREAS. SUNDAY SHOULD BEGIN THE WARMUP AS HIGH
PRESSURE ALOFT MOVES CLOSER. EXTENDED WILL BE DRY...STARTING OUT WITH
RIDGE ALOFT FOLLOWED BY TROUGHING TO OUR N. THIS TROUGH WILL STAY FAR
ENOUGH TO THE N TOn KEEP US DRY BUT WILL PROBABLY BRING HALT TO
WARMUP. PLEASE REFER TO LATEST STATEMENTS FROM PHX NWS OFFICE FOR
DETAILS REGARDING SNOW ADVISORY.  ESTLE