Severe Thunderstorm Warning 29, NWS Phoenix, AZ

AZZ020>028-CAZ030>033-142245-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1040 AM MST TUE AUG 14 2001

.SYNOPSIS...
A WEAK DISTURBANCE ACROSS ARIZONA TODAY WILL SERVE TO PRODUCE
ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND
EVENING...MAINLY OVER SOUTH-CENTRAL ARIZONA. MEANWHILE...SOMEWHAT
DRIER AND MORE STABLE AIR MOVING IN FROM THE WEST WILL PROVIDE FOR
ONLY SPARSE THUNDERSTORM ACTIVITY IN SOUTHEAST CALIFORNIA. UPPER
LEVEL HIGH PRESSURE PUSHING IN FROM THE WEST AFTER MIDWEEK WILL MAKE
FOR HOTTER DAYTIME TEMPERATURES...WITH DRIER AIR EXPECTED TO
INFILTRATE MOST OF SOUTH-CENTRAL ARIZONA...FOR DECREASING CHANCES OF
DAILY THUNDERSTORMS. BY EARLY NEXT WEEK...THE HIGH WILL MOVE NORTH
OF THE REGION AND WILL ALLOW MOISTURE AND THUNDERSTORMS TO RETURN TO
THE FORECAST AREA.

.DISCUSSION...
PLOTS SHOW HIGH MOISTURE VALUES AT 850 AND 700 MB AGAIN...EVEN IN
SOUTHEAST CALIFORNIA. MODEST HEIGHT FALLS EVIDENT AT 500 MB. A COL
AREA AT THE 300/250 MB LEVELS WAS PRESENT OVER PORTIONS OF SOUTHEAST
CALIFORNIA AND WESTERN ARIZONA WITH WITH A SHORTWAVE TROUGH OVER THE
GREAT BASIN. SOME SLIGHT COOLING OF THE TEMPERATURE PROFILES HAS
TAKEN PLACE SINCE YESTERDAY MORNING ALONG WITH SOME DECREASES IN
PWATER...ESPECIALLY AT DRA AND 1Y7. WIND PROFILES HAVE SHOWN SOME
VEERING IN THE MID AND UPPER LEVELS. NO BIG CHANGES IN CAPE EXCEPT
WHERE THERE WAS SIGNIFICANT DRYING. OTHERWISE...ONLY MINOR CHANGES
IN STABILITY THROUGH TEMPERATURE PROFILE CHANGES WITH SLIGHTLY
COOLER TEMPS ALOFT AND SLIGHTLY WARMER TEMPS IN THE LOWER LEVELS.

MODELS SHOW STEERING FLOW FOR OUR CWA TO BECOME NORTHEASTERLY BY
THIS AFTERNOON. THE UPPER LEVEL COL AREA IS PROGGED TO SLIDE
SOUTHWARD AWAY FROM US FOR LESS HELP IN STORM ACTIVITY. HOWEVER SOME
DIFFLUENCE SHOULD BE AROUND...MAINLY OVER SOUTHWEST ARIZONA AND
SOUTHEAST CALIFORNIA. PROGS CONTINUE TO SHOW DRYING TREND AS RIDGE
AXIS BUILDS INTO THE WEST. AVN FASTER WITH DRYING THAN ETA...BUT IT
APPEARS THEY HAVE SLOWED THE DRYING A BIT. IN SHORT TERM...WOULD
EXPECT ANOTHER ACTIVE PERIOD NEXT 12 HOURS OR SO. BY
THURSDAY...DRIER AIR THROUGH A DEEP LAYER SHOULD BE IN PLACE FOR A
SIGNIFICANT DECREASE IN THUNDERSTORM ACTIVITY. BELIEVE THE AVN TOO
QUICK WITH DRYING SO EXPECT SOME MENTION OF STORM ACTIVITY WEDNESDAY
NIGHT. HOWEVER...IT WILL HAVE TO COME IN FROM THE HIGHER TERRAIN
WITH MAINLY SOUTH-CENTRAL ARIZONA PORTION OF CWA HAVING THE MAIN
THREAT.

JAMISON

AZZ020>028-150200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
1245 PM MST TUE AUG 14 2001

...HAZARDOUS WEATHER POSSIBLE OVER SOUTH-CENTRAL AND SOUTHWEST
ARIZONA THIS AFTERNOON AND TONIGHT...

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

THE PRIMARY HAZARDOUS WEATHER RISKS INCLUDE:
     LOCALIZED VERY HEAVY RAIN...AND STRONG GUSTY WINDS.

STORM SPOTTER ACTIVATION MAY BE NECESSARY LATE THIS AFTERNOON AND
TONIGHT.

JAMISON

AZZ020>028-150200-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
1245 PM MST TUE AUG 14 2001

...HAZARDOUS WEATHER POSSIBLE OVER SOUTH-CENTRAL AND SOUTHWEST
ARIZONA THIS AFTERNOON AND TONIGHT...

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

THE PRIMARY HAZARDOUS WEATHER RISKS INCLUDE:
     LOCALIZED VERY HEAVY RAIN...AND STRONG GUSTY WINDS.

STORM SPOTTER ACTIVATION MAY BE NECESSARY LATE THIS AFTERNOON AND
TONIGHT.

JAMISON