Damaging Wind in Arizona, July 10, 2002

AZZ020>028-CAZ030>033-110545-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
325 PM MST WED JUL 10 2002

.SYNOPSIS...
STRONG HIGH PRESSURE ALOFT OVER THE GREAT BASIN WILL SHIFT A BIT TO
THE EAST THE NEXT FEW DAYS...WITH THE HIGH CENTER MOVING INTO UTAH
OVER THE WEEKEND. THIS WILL CONTINUE TO BRING A DEEP EASTERLY FLOW
ACROSS SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA THROUGH THE
REMAINDER OF THIS WEEK. THIS WILL IMPORT MOISTURE FROM THE
EAST...PROVIDING A GOOD START TO THE SUMMER THUNDERSTORM SEASON. IN
ADDITION...A SERIES OF MINOR LOW PRESSURE SYSTEMS WILL BE MOVING
WESTWARD OVER NORTHERN MEXICO AND ARIZONA...CONTINUING THE THREAT
FOR THUNDERSTORM ACTIVITY. LOOK FOR A CONTINUED CHANCE OF SHOWERS
AND THUNDERSTORMS...WITH SOME BLOWING DUST ON THE LOWER DESERTS...AS
THE WEEK PROGRESSES.

.DISCUSSION...
MONSOON IN FULL SWING ALREADY...AND THE OFFICIAL START SHOULD BE
YESTERDAY...JULY 9...AS THE AVERAGE DEWPOINT WAS 58...AND SHOULD
STAY AT OR ABOVE 55F TODAY AND THU. STRONG UPPER HIGH REMAINS
CENTERED OVER SRN NV...BRINGING A DEEP ELY FLOW TO THE STATE. QUITE
A BIT OF MOISTURE HAS SPREAD OVER MOST OF THE CWA...WITH THE HIGHEST
PWAT VALUES...TO OVER 1.5 INCHES...OVER SWRN AZ AND SERN CA PER THE
GOEW PWAT IMAGERY. ATMOSPHERE QUITE UNSTABLE TODAY WITH LIFTED
INDICES BETWEEN MINUS 4 AND MINUS 7 OVER THE AZ RAOBS...AND THE
CLOUDS HAD CLEARED SUFFICIENTLY TO GIVE GOOD SOLAR HEATING THIS
AFTERNOON. IN ADDITION TO THE HEATING AND TERRAIN INFLUENCES WE HAVE
DISTURBANCES ROTATING AROUND THE HIGH OUT OF NM...AND OVER FAR
WCNTRL AZ...WHICH WILL HELP TRIGGER STORMS. A LOOK AT THE CURRENT
RADAR SHOWS STORMS FIRING NICELY AT 3 PM ALONG THE RIM...AND OVER
THE SRN AZ MOUNTAINS. STORMS SHOULD MOVE WEST AND OVER THE LOWER
DESERTS...FEEDING OFF THE HIGH LOW LEVEL MOISTURE THAT IS NOW IN
PLACE. SFC DEWPOINTS ARE IN THE 60S NOW OVER MOST OF OUR DESERTS SO
THE AMS IS RIPE TO SUPPORT CONVECTION OVER OUR LOWER TERRAIN
TONIGHT. WILL CALL FOR A CHANCE FOR STORMS OVER THE SOUTH-CENTRAL
TONIGHT AND A 20 PERCENT CHANCE FOR THE WESTERN DESERTS AND THE SERN
CA DESERTS. WILL SEE STRONG GUSTY AND POTENTIALLY DAMAGING WINDS
WITH THESE STORMS ALONG WITH BLOWING DUST LOWERING VSBYS TO WELL
BELOW ONE MILE IN PLACES...TO NEAR ZERO IN SPOTS. WITH PWAT SO HIGH
COULD ALSO SEE LOCALLY HEAVY RAIN WITH SOME OF THE STRONGER
STORMS...ENOUGH TO WARRANT URBAN SMALL STREAM FLOOD ADVISORIES OR
EVEN FLASH FLOOD WARNINGS. HAVE ISSUED A HAZARDOUS WEATHER OUTLOOK
FOR THE SCNTRL ZONES FROM 3 PM THRU MIDNIGHT TONIGHT.
OTHERWISE...REST OF THE FORECAST TO BE QUITE SIMILAR AND BROAD
BRUSHED...WITH THE STANDARD MONSOON FORECAST IN PLACE. THIS BECAUSE
ALL MODELS KEEP THE BASIC FLOW PATTERN IN PLACE...WITH THE STRONG
HIGH OVER THE WESTERN STATES...CENTERED TO OUR NORTH...KEEPING THE
MOIST EAST FLOW OVER OUR AREA. WITH AMS TO BE UNSTABLE EACH DAY
THERE WILL BE A CHANCE FOR STORMS TO FORM OVER THE HIGHER TERRAIN IN
THE AFTERNOON AND THEN MOVE WITH THE ELY STEERING WINDS DOWN OVER
THE LOWER DESERTS IN THE LATE AFTERNOON AND EVENING HOURS. BETTER
CHANCES WILL BE IN THE SCNTRL ZONES...DOWN TO MOSTLY SLIGHT CHANCES
OVER THE WESTERN DESERTS. TEMPS WILL NOT CHANGE MUCH...AS THE HIGH
REMAIN STRONG FOR SOME TIME...BUT IS IT FORECAST TO WEAKEN A BIT
LATE IN THE PERIOD...SO WILL DROP TEMPS 2-3 DEGREES FROM SUN THROUGH
WED.  11

.PSR...NONE.

AZZ022>024-027-028-110400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
106 PM MST WED JUL 10 2002

...HAZARDOUS WEATHER POSSIBLE OVER PORTIONS OF SOUTH-CENTRAL ARIZONA
FROM 3 PM TODAY UNTIL MIDNIGHT TONIGHT...

COUNTIES IN SOUTH-CENTRAL ARIZONA IN THE RISK AREA INCLUDE...
     MARICOPA...NORTHWEST PINAL AND SOUTHERN GILA.

THE PHOENIX METROPOLITAN AREA IS INCLUDED IN THE OUTLOOK...BUT
MAINLY AFTER 600 PM.

THE PRIMARY HAZARDOUS WEATHER RISKS INCLUDE: THUNDERSTORMS
     WITH STRONG AND DAMAGING WINDS TO OVER 50 MPH ALONG
     WITH BLOWING DUST ON THE DESERTS LOWERING VISIBILITIES TO
     LESS THAN ONE-QUARTER MILE.

ADDITIONAL THREATS INCLUDE: BRIEF HEAVY RAINFALL AND DEADLY
     LIGHTNING.

STORM SPOTTER ACTIVATION MAY BE NECESSARY LATER TODAY.