Severe Thunderstorm Warning 15, NWS Phoenix, AZ

AZZ020>028-CAZ030>033-120545-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
255 PM MST THU JUL 11 2002

.SYNOPSIS...
STRONG HIGH PRESSURE ALOFT WILL REMAIN CENTERED IN THE VICINITY OF
IDAHO...UTAH...AND WYOMING AT LEAST THROUGH EARLY NEXT WEEK. THIS
MEANS A CONTINUATION OF HUMID AND UNSTABLE AIR FROM THE EAST IN THE
CLOCKWISE FLOW AROUND THE HIGH PRESSURE CENTER. THIS WILL RESULT IN
SCATTERED MAINLY AFTERNOON AND EVENING THUNDERSTORMS...AND BLOWING
DESERT DUST.

.DISCUSSION...
A HUMID AND UNSTABLE AIRMASS CONTINUES WITH TODAY EXPECTED TO BE THE
THIRD DAY IN A ROW WITH THE AVERAGE SURFACE DEW POINT TEMPERATURE AT
PHOENIX SKY HARBOR EXPECTED TO BE ABOVE 55 DEGREES. STRONG HIGH
PRESSURE ALOFT WILL REMAIN CENTERED NORTH OF ARIZONA THE REST OF THE
WEEK AND AT LEAST THROUGH EARLY NEXT WEEK. THIS MEANS A CONTINUATION
OF HUMID AND UNSTABLE AIR FROM THE EAST IN THE CLOCKWISE FLOW AROUND
THE HIGH PRESSURE CENTER. FORECAST AT THIS TIME OF YEAR IS MORE THAN
THE USUAL CHALLENGE. IT LOOKS AS IF THERE IS A WEAK LOW PRESSURE
SYSTEM IN THE FLOW FROM THE EAST THAT WILL MOVE WEST ACROSS CENTRAL
AND SOUTHERN ARIZONA TONIGHT WHICH WILL HELP TO TRIGGER THE
DEVELOPMENT OF THUNDERSTORMS IN SOUTH-CENTRAL ARIZONA TONIGHT WITH A
POSSIBILITY OF SOME STORMS CONTINUING OR REDEVELOPING DURING THE
NIGHT. THE LOWEST LEVELS OF THE ATMOSPHERE ARE STILL RELATIVELY DRY.
SO IT LOOKS AS IF THE MAIN THING TO WATCH FOR IS GUSTY WIND WITH
BLOWING DUST...AND OF COURSE LIGHTNING.

.PSR...NONE.

ELLIS

AZZ021>024-026>028-120000-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
130 PM MST THU JUL 11 2002

...HAZARDOUS WEATHER POSSIBLE OVER PORTIONS OF SOUTH-CENTRAL AND
SOUTHWEST ARIZONA FROM 2 PM TODAY UNTIL MIDNIGHT TONIGHT...

COUNTIES IN THE RISK AREA INCLUDE...MARICOPA...NORTHWEST
PINAL...SOUTHERN GILA....CENTRAL AND EASTERN LA PAZ AND YUMA

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

ADDITIONAL THREATS INCLUDE: CLOUD TO GROUND LIGHTNING. BRIEF HEAVY
RAIN IS POSSIBLE...ESPECIALLY OVER THE WESTERN PORTION OF THE
OUTLOOK AREA.

STORM MOVEMENT WILL BE TOWARD THE WEST AT 15 MPH. THE THREAT FOR
HAZARDOUS WEATHER OVER THE LOWER DESERT WILL INCREASE LATE THIS
AFTERNOON AND EARLY EVENING...WITH THE THREAT GRADUALLY SHIFTING FROM
EAST TO WEST ACROSS THE OUTLOOK AREA THIS EVENING. THE PHOENIX
METROPOLITAN AREA IS INCLUDED IN THE OUTLOOK...BUT MAINLY AFTER 6 PM.

STORM SPOTTER ACTIVATION MAY BE NECESSARY LATER TODAY.