Severe Thunderstorm Warning 12, NWS Phoenix, AZ

AZZ020>028-CAZ030>033-211045-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX ARIZONA
1000 PM MST SUN JUL 20 2003

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE TO DRIFT WEST ACROSS NORTHERN ARIZONA
TONIGHT...THEN MOVE OVER SOUTHERN NEVADA MONDAY. THERE IS A CHANCE
OF MAINLY EVENING SHOWERS AND THUNDERSTORMS OVER THE LOWER DESERT
OF SOUTH CENTRAL ARIZONA TONIGHT...AND A BETTER CHANCE FOR STORMS
OVER THE SOUTHWEST AND SOUTH-CENTRAL ARIZONA MONDAY NIGHT. RATHER
TYPICAL LATE JULY WEATHER IS EXPECTED THE REST OF THE WEEK...WITH
AFTERNOON STORMS POSSIBLE OVER THE HIGHER TERRAIN AND EVENING STORMS
POSSIBLE OVER THE LOWER DESERT. TEMPERATURES WILL AVERAGE A FEW
DEGREES ABOVE NORMAL THIS WEEK.

.DISCUSSION...
STRONG UPPER HIGH IN PLACE OVER THE WESTERN STATES CENTERED OVER
UTAH GIVING A FAIRLY BRISK ELY STEERING FLOW ACROSS SRN AZ ATTM.
SKIES WERE CLEAR OVER MOST OF THE CWA MOST OF THE EVENING...WITH
CONVECTION SLOW TO START TO OUR EAST. HOWEVER...AN INVERTED TROF
MOVING AROUND THE EAST SIDE OF THE HIGH IS NOW MOVING INTO FAR
ECNTRL AZ...AND STRONG UVV AND DIFLUENCE CAN BE SEEN ON THE PLOTS
AND PROGS MOVING INTO ERN AZ AND OUR ERN CWA. STRONG CONVECTION NOW
FIRING OVER SERN AZ AND OVER THE ERN RIM...DOWN INTO SRN GILA...AND
THE STEERING FLOW IS TAKING THESE STORMS INTO ERN MARICOPA COUNTY AT
1000 PM. ALTHOUGH DEWPOINTS OVER THE SCNTRL DESERTS ARE NOT OVERLY
HIGH...IN THE LOW TO MID 50S MANY PLACES...STILL NEARLY 1.25 INCHES
PWAT IN THE SOUNDINGS...AND THERE IS DECENT INSTABILITY AROUND PER
THE 00Z RAOBS. STRONG WLY FLOW ACRSS THE CENTRAL DESERTS SEEN IN THE
KIWA VAD WIND PROFILE...GIVING GOOD INFLOW INTO THE WRN FLANKS OF
THE STORMS...AND THERE IS SOME SHEAR SEEN IN THE HODOGRAPHS TO AID
STORM ORGANIZATION. AS THE VORT MAX CONTINUES TO ROTATE AROUND THE
HIGH AND INTO OUR ERN CWA TONIGHT WEATHER WILL LIKELY BE
ACTIVE...WITH SOME SEVERE STORMS LIKELY. TEMPS WARMED UP SEVERAL
MORE DEGREES TODAY...TOPPING OUT AT 112 AT PHX...SO THERE IS PLENTY
OF ENERGY IN THE LOWER AMS TO BE RELEASED WITH THE CONVECTION.
UPDATED FORECASTS TO INCREASE CHANCES FOR SHOWERS AND STORMS
TONIGHT...AND ALSO INCREASED CLOUD COVER ACROSS OUR CWA...AS LOTS OF
DEBRIS CLOUDS WILL BE OVERSPREADING OUR AREA OVER NIGHT. MONDAY ALSO
LOOKS RATHER ACTIVE...AS MORE SHORT WAVES WILL BE COMING AROUND THE
HIGH...AND THE UPPER FLOW WILL TURN MORE TO THE NE...A FAVORABLE
DIRECTION TO BRING RIM STORMS INTO THE DESERTS.  CURRENT FORECASTS
ARE PRETTY GOOD...BUT CONVECTION MAY FORCE MORE SHORT TERM UPDATES.
11

.PSR...NONE.

AZZ020>028-CAZ030>033-210100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
600 AM MST SUN JUL 20 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWEST AND
SOUTH-CENTRAL ARIZONA...AND SOUTHEAST CALIFORNIA.

.DAY ONE...TODAY

SCATTERED STRONG THUNDERSTORMS WILL DEVELOP OVER THE HIGHER TERRAIN
OF SOUTH CENTRAL ARIZONA THIS AFTERNOON. ISOLATED THUNDERSTORMS AND
AREAS OF DENSE BLOWING DUST WILL BE POSSIBLE OVER THE LOWER DESERT
OF SOUTH CENTRAL ARIZONA TONIGHT. STRONGEST STORMS WILL BE CAPABLE
OF PRODUCING DAMAGING STRAIGHT LINE WIND...INTENSE CLOUD TO GROUND
LIGHTNING...AND BRIEF HEAVY RAIN.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

UPPER LEVEL STEERING FLOW WILL BE FROM THE NORTHEAST...EAST...OR
SOUTHEAST THIS WEEK AS STRONG HIGH PRESSURE ALOFT REMAINS OVER THE
INTERMOUNTAIN WEST. EXPECT STORMS TO DEVELOP OVER THE HIGHER TERRAIN
DURING THE AFTERNOON...THEN OVERSPREAD PORTIONS OF THE LOWER DESERT
EACH EVENING. STRONGEST STORMS MAY PRODUCE DAMAGING STRAIGHT LINE
WIND AS WELL AS BRIEF HEAVY RAIN AND INTENSE CLOUD TO GROUND
LIGHTNING. BLOWING DUST WILL OCCUR NEAR STORMS WHICH DEVELOP OVER
THE LOWER DESERT.