Severe Thunderstorm Warning 50, NWS Phoenix, AZ

AZZ020>028-CAZ030>033-062245-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
950 AM MST SAT OCT 6 2001

.SYNOPSIS...
A SERIES OF LOW PRESSURE SYSTEMS WILL AFFECT THE SOUTHWEST UNITED
STATES THIS WEEKEND AND INTO NEXT WEEK. MOISTURE FROM MEXICO WILL BE
PULLED UP INTO MUCH OF ARIZONA AHEAD OF THESE SYSTEMS...LEADING TO A
SLIGHT CHANCE OF A SHOWER OR THUNDERSTORM THIS AFTERNOON OVER
PORTIONS OF SOUTH-CENTRAL ARIZONA. THE CHANCE OF SHOWERS AND
THUNDERSTORMS WILL INCREASE TONIGHT...AND CONTINUE OVER MAINLY
SOUTH-CENTRAL ARIZONA THROUGH COLUMBUS DAY. IT WILL ALSO BE COOLER
DURING THIS TIME. AFTER COLUMBUS DAY...A DRIER NORTHWEST FLOW ALOFT
WILL TAKE OVER THE WEATHER ACROSS THE REGION. IT WILL GIVE LOCALLY
WINDY CONDITIONS ON TUESDAY ALONG WITH A LINGERING CHANCE OF SHOWERS
OVER THE HIGHER TERRAIN. IT WILL BE WINDY AT TIMES THE REMAINDER OF
THE WORK WEEK WITH PARTLY CLOUDY SKIES.

.DISCUSSION...
APPEARS FIRST MEASURABLE RAIN EVENT IN OVER A MONTH LOOMING ON THE
HORIZON FOR AT LEAST PHX AREA NEXT 24 TO 48 HOURS AS SIGNIFICANT
TROUGH SYSTEM DEVELOPS OFF SRN CA COAST. BACKING FLOW AHEAD OF THIS
TROUGH OVER THE CENTRAL/ERN CWFA CONTINUES TO PULL UP PLENTIFUL
LOW/MID LEVEL MOISTURE FROM THE S. FORECAST EGGS WERE PLACED IN THE
AVN BASKET YESTERDAY...AND THIS STILL APPEARS BEST WAY TO GO. SYSTEM
HAS GOOD DARKENING FEATURE ASSOCIATED WITH IT ON WV IMAGERY...WITH
JET STREAK ALSO FORMING ON THE SOUTH FLANK. WITH EVERYTHING
SEEMINGLY COMING TOGETHER FOR PRECIP...MID SHIFT KEPT POPS IN THE
CHANCE CATEGORY...BUT ALSO RIGHTLY BEEFED POPS UP IN SW AZ. BOTH AVN
AND ETA ATTEMPTING TO WRAP MOISTURE BRIEFLY INTO SE CA ZONES AS WELL
THIS AFTERNOON THRU TONIGHT. 10Z KYUM SOUNDING CONTAINS FAIR AMOUNT
OF CAPE...AND WITH DYNAMICS HEADED THAT DIRECTION...WILL UPDATE SW
AZ AND SE CA ZONES TO INCLUDE SLIGHTLY HIGHER POPS THIS AFTERNOON
AND TONIGHT. OTHERWISE...EXISTING FORECASTS APPEAR TO BE IN DECENT
SHAPE FOR NOW. SOME AFTERNOON PACKAGE CHANGES MAY INCLUDE EVEN
HIGHER POPS FOR TONIGHT THRU SUNDAY...PER LATEST AVN/FAN GUIDANCE.
WILL ALSO ISSUE A SPECIAL WEATHER STATEMENT LATER TODAY HIGHLIGHTING
THE CHANGE TO MUCH WETTER AND COOLER WEATHER THRU REMAINDER OF
HOLIDAY WEEKEND. ESTLE

.PSR...NONE.

AZZ020>028-CAZ030>033-070530-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PHOENIX AZ
1027 AM MST SAT OCT 6 2001

...SIGNIFICANT WEATHER CHANGES HEADED FOR SOUTHWEST AND SOUTH-
CENTRAL ARIZONA AND SOUTHEAST CALIFORNIA THIS WEEKEND...

A SERIES OF LOW PRESSURE SYSTEMS WILL AFFECT ARIZONA AND SOUTHEAST
CALIFORNIA THE NEXT SEVERAL DAYS. THE FIRST SYSTEM...NOW OFF THE
SOUTHERN CALIFORNIA COAST...WILL GIVE AN INCREASING CHANCE OF
SHOWERS AND THUNDERSTORMS LATER TODAY THROUGH COLUMBUS DAY. THE BEST
CHANCES FOR SIGNIFICANT RAINFALL OVER THE NEXT TWO OR THREE DAYS
WILL BE OVER SOUTH-CENTRAL ARIZONA...WHERE SOME SPOTS COULD RECEIVE
OVER A HALF INCH. FURTHER WEST...SOUTHEAST CALIFORNIA WILL PROBABLY
ONLY HAVE A THREAT OF SHOWERS INTO EARLY SUNDAY.

IN ADDITION TO THE INCREASING RAIN CHANCES...THE CLOUDS AND SHOWERS
WILL MAKE FOR MUCH COOLER WEATHER...WITH DESERT HIGH TEMPERATURES
LIKELY TO RISE ONLY INTO THE 80S BEGINNING SUNDAY.

RAIN CHANCES WILL DECREASE ACROSS SOUTH-CENTRAL ARIZONA BY LATE
COLUMBUS DAY...WITH YET ANOTHER LOW PRESSURE SYSTEM EXPECTED TO DROP
DOWN...THIS ONE FROM THE NORTHWEST...ON TUESDAY. THIS SYSTEM WILL
BRING MUCH DRIER AIR INTO THE AREA...ALONG WITH COOLER TEMPERATURES
AND LOCALLY WINDY CONDITIONS. FINALLY...A THIRD LOW PASSING TO OUR
NORTH WILL HELP TO REINFORCE THE COOL..DRY...LOCALLY WINDY WEATHER
PATTERN LATE NEXT WEEK. IT IS POSSIBLE THAT SOME OF THE COOLEST
DESERT SPOTS...SUCH AS WICKENBURG...MAY SEE LOW TEMPERATURES DOWN IN
THE 40S BY THURSDAY OR FRIDAY.

PERSONS WITH OUTDOOR ACTIVITIES THE NEXT SEVERAL DAYS SHOULD KEEP UP
WITH THE LATEST WEATHER FORECASTS...AND BE PREPARED FOR THE
POTENTIALLY WET...COOLER WEATHER.

ESTLE