Severe Thunderstorm Warning 37, NWS Phoenix, AZ

AZZ020>028-CAZ030>033-150545-

SOUTHWEST ARIZONA/SOUTHEAST CALIFORNIA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
320 PM MST THU AUG 14 2003

.SYNOPSIS...
VERY UNSETTLED WEATHER WILL BE THE RULE ACROSS SOUTHWEST ARIZONA AND
SOUTHEAST CALIFORNIA INTO THE WEEKEND AS AN UPPER LOW DRIFTS OVER
THE REGION FROM THE EAST. STRONG THUNDERSTORMS WILL RUMBLE ACROSS
SOUTH-CENTRAL ARIZONA THIS EVENING...WITH THE POTENTIAL FOR SEVERE
WEATHER. AFTER TONIGHT...A CHANCE OF SHOWERS AND THUNDERSTORMS WILL
CONTINUE...WITH ACTIVITY EXPECTED TO DECREASE SOMEWHAT OVER THE
UPCOMING WEEKEND. TEMPERATURES WILL BE WELL BELOW NORMAL ACROSS
SOUTH-CENTRAL ARIZONA ON FRIDAY DUE TO THE RAIN-COOLED AIR...WITH
READINGS EXPECTED TO REBOUND OVER THE WEEKEND. THE WEATHER WILL
RETURN TO A MORE NORMAL MONSOON PATTERN THE FIRST PART OF NEXT WEEK.

.DISCUSSION...
LOTS OF PARAMETERS COMING TOGETHER FOR A VERY ACTIVE EVENING ACROSS
MAINLY ERN CWFA. THESE FACTORS INCLUDE A VERY MOIST...UNSTABLE
AIRMASS...A FAVORABLE NELY STEERING FLOW WITH LOTS OF SHEER IN THE
0-6KM LAYER...DIVERGENCE ALOFT WITH LARGE SCALE MID LEVEL CONVERGENCE
...DYNAMICS WITH APPROACHING INVERTED TROF...IE JUST ABOUT ALL ONE
COULD ASK FOR TO ENSURE LOTS OF WEATHER. AS A RESULT...HAVE GONE
WITH VERY HIGH POPS FOR SCNTRL AZ TONIGHT INTO FRIDAY MORNING WITH
LOWER NUMBERS FURTHER W. SPC ISSUED A SEVERE THUNDERSTORM WATCH
EARLIER THIS AFTERNOON FOR BASICALLY SOUTH-CENTRAL INTO NE AZ TIL
04Z. IN ADDITION...HEAVY RAIN THREAT HAS PROMPTED US TO ISSUE FLASH
FLOOD WATCH FOR SCTNRL AZ UNTIL 12Z FRIDAY.

AFTER TONIGHT...INVERTED TROF MOVES INTO AZ AND THEN MEANDERS NWD
DURING THE WEEKEND. COOLER AIR ALOFT WILL SERVE TO DESTABLIZE THE
AMS EVEN FURTHER FRIDAY AND SATURDAY...ALTHOUGH IF TONIGHT IS ACTIVE
...WE WOULD HAVE LOTS OF CONVECTIVE INHIBITION TO OVERCOME IN THE
ABSENCE OF MORE UPPER FORCING. WE MAY HAVE SOME OF THAT BOTH FRIDAY
AND SATURDAY AS ADDITIONAL VORT MAXIMA ROTATE AROUND TROUGH. SO...
WILL BASICALLY KEEP CHANCE TYPE POPS GOING INTO SATURDAY...LOWERING
POPS A BIT ON SUNDAY...WITH A LOW GRADE MONSOON FORECAST MAINTAINED
MONDAY THRU THURSDAY.

.PSR...SVR TSTM WATCH SCNTRL AZ...ZONES 22...23...24...27 AND
       28 TIL 04Z.
       FLASH FLOOD WATCH SAME ZONES 00Z-12Z.

AZZ020>028-CAZ030>033-150100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PHOENIX AZ
619 AM MST THU AUG 14 2003

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

.DAY ONE...TODAY

THERE IS A CHANCE OF SHOWERS AND THUNDERSTORMS IN SOUTHWEST AND
SOUTH CENTRAL ARIZONA. THE STRONGEST STORMS WILL OCCUR LATE THIS
AFTERNOON AND EVENING. THUNDERSTORMS ARE CAPABLE OF PRODUCING STRONG
POSSIBLY DAMAGING WINDS...DENSE BLOWING DUST...AND LOCALLY HEAVY
RAIN.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

AN UNUSUALLY STRONG LOW PRESSURE SYSTEM MOVING FROM TEXAS INTO
ARIZONA WILL CONTINUE THE UNSETTLED WEATHER ON FRIDAY. A CHANCE FOR
SHOWERS AND THUNDERSTORMS CAN BE EXPECTED ACROSS PARTS OF SOUTHEAST
CALIFORNIA...AND SOUTHWEST AND SOUTH CENTRAL ARIZONA.  THUNDERSTORMS
ARE CAPABLE OF PRODUCING STRONG POSSIBLY DAMAGING WINDS...DENSE
BLOWING DUST...AND HEAVY RAINFALL.

DECREASING THREATS FOR SHOWERS AND THUNDERSTORMS ARE EXPECTED
THIS WEEKEND AND EARLY NEXT WEEK.

.INSTRUCTIONS TO SPOTTERS...
WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS ACCORDING TO STANDARD OPERATING PROCEDURES.