Severe Thunderstorm Warning 29, NWS Phoenix, AZ

AZZ020>028-CAZ030>033-070545-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
250 PM MST SUN AUG 6 2000

.SYNOPSIS...
THE CHANCE FOR MAINLY LATE AFTERNOON AND NIGHTTIME STORMS WILL
CONTINUE OVER SOUTH CENTRAL ARIZONA INTO AT LEAST THE MIDDLE OF NEXT
WEEK AS A MORE TYPICAL MONSOON FLOW BECOMES ESTABLISHED. IN
ADDITION...SOUTHWEST ARIZONA WILL SEE A SLIGHT CHANCE FOR STORMS
THROUGH MID WEEK. DAYTIME HIGH TEMPERATURES WILL RANGE FROM A BIT
BELOW TO SLIGHTLY ABOVE SEASONAL NORMALS.

.DISCUSSION...
CONVECTION NOW BREAKING OUT NICELY ALONG THE MOGOLLON RIM TO THE N
AND E OF THE CWA...AND THE STEERING FLOW ALOFT IS WEAKLY FROM THE
NE...WHICH IS SOMEWHAT FAVORABLE FOR HELPING STEER THE STORMS DOWN
OFF THE HIGHER TRRN INTO THE SCNTRL DESERTS. MOISTURE REMAINS HIGH
OVER THE DESERTS...WITH DEWPOINTS IN THE 60S...SO STORMS COMING OFF
THE MOUNTAINS ARE MOVING INTO A MORE FAVORABLE ENVIRONMENT AND SHOULD
BE ABLE TO SUSTAIN THEMSELVES. ALSO..OUTFLOWS FROM THESE STORMS
SHOULD BE ABLE TO TRIGGER NEW CONVECTION OVER THE DESERTS. ONLY FLY
IN THE OINTMENT IS THAT THE BOUNDARY LAYER IS 5 TO 10 DEGREES COOLER
COMPARED TO YESTERDAY...THE RESULT OF PREVIOUS CONVECTION. AS AS
RESULT...STORMS HAVE YET TO GET GOING OVER THE SE OR SCNTRL..AND THIS
LACK OF HEATING MAY CAUSE THE NIGHT TO BE A DUD. STILL...CALLING FOR
A CHANCE FOR NIGHTTIME STORMS OVER SCNTRL AZ...WITH A SLIGHT CHANCE
TO THE CO RIVER. PROGS GRADUALLY SHIFT THE  HIGH EWD TOMORROW...WITH
THE FLOW ALOFT BECOMING WEAKER...BUT THE DEFORMATION ZONE STAYS MORE
OR LESS IN PLACE WITH CONSIDERABLE MOISTURE SLATED TO BE OVER THE
SERN PART OF THE STATE...AND OVER THE ERN CWA. MESOETA BRINGS
IMPRESSIVE VORT MAX FROM NM INTO SERN AND SCNTRL AZ MON AND THIS
COULD LEAD TO AN UNSETTLED...SHOWERY DAY MON. TROFFING STILL FORECAST
TO SET UP ALONG THE WEST COAST BY TUE...WHICH WILL SHIFT THE HIGH
BACK NEAR THE FOUR CORNERS...AND KEEP THE FAR WRN PARTS OF THE CWA
DRY AND STABLE ENOUGH TO PRECLUDE ANY STORM DEVELOPMENT...WITH THE
CHANCES FOR STORMS CONFINED TO THE WRN DESERTS AND THE SCNTRL. WITH A
MORE TYPICAL MONSOON FLOW PATTERN IN PLACE...IN THE WED THRU FRI TIME
PERIOD...WILL CALL FOR THE STANDARD MONSOON FORECAST WHICH IS A
CHANCE FOR AFTN AND EVE SHOWERS AND THUNDERSTORMS...MAINLY FOR THE
SCNTRL. 11

AZZ022>024-027-028-070130-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
1050 AM MST SUN AUG 6 2000

...SLIGHT RISK FOR SEVERE THUNDERSTORMS OVER SOUTH-CENTRAL
ARIZONA THIS EVENING...

THE SLIGHT RISK AREA ENCOMPASSES MARICOPA...SOUTHERN GILA AND
NORTHWEST PINAL COUNTIES. IT INCLUDES THE GREATER PHOENIX
METROPOLITAN AREA AS WELL AS THE CITIES OF GLOBE...COOLIDGE...CASA
GRANDE...GILA BEND AND WICKENBURG.

THE PRIMARY WEATHER THREATS FROM THE THUNDERSTORMS TONIGHT WILL BE
LOCALLY HEAVY RAINFALL WHICH MAY CAUSE FLOODING OF WASHES...STREETS
AND LOW LYING AREAS...STRONG GUSTY AND POSSIBLY DAMAGING WINDS...AND
BLOWING DUST THAT COULD LOWER VISIBILITIES TO BELOW ONE-QUARTER MILE
IN PLACES. IN ADDITION...DEADLY CLOUD TO GROUND LIGHTNING IS LIKELY
WITH THESE THUNDERSTORMS.

SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER THE HIGHER
TERRAIN OF BOTH CENTRAL AND EASTERN ARIZONA...THEN GRADUALLY WORK
THEIR WAY SOUTH AND WEST DURING THE LATE AFTERNOON AND EVENING
HOURS. STORMS COULD PERSIST PAST MIDNIGHT...BUT THE CHANCES FOR
SEVERE WEATHER WITH THEM WILL BE GREATLY REDUCED.

STORM SPOTTER ACTIVATION MAY BE NECESSARY LATER TODAY.

CJB