Severe Thunderstorm Warning 1, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
130 PM MST THU MAY 29 2003

.SYNOPSIS...THE STEERING FLOW AROUND HIGH PRESSURE CENTERED NEAR THE
FOUR CORNERS AND LOW PRESSURE OVER BAJA WILL BRING AN INCREASE IN
MOISTURE TO SOUTHERN ARIZONA THROUGH AT LEAST SATURDAY. THIS
MOISTURE WILL PROVIDE THE AREA WITH ISOLATED MAINLY AFTERNOON AND
EARLY EVENING SHOWERS AND THUNDERSTORMS THE NEXT FEW DAYS. THE BEST
CHANCE OF THUNDERSTORMS WILL BE NEAR THE INTERNATIONAL BORDER
TONIGHT...WITH THE AREAL COVERAGE OF STORMS INCREASING FRIDAY. DRIER
AIR IS FORECAST TO SPREAD OVER THE REGION STARTING THIS WEEKEND INTO
EARLY NEXT WEEK AS A LOW PRESSURE SYSTEM MOVES INTO NORTHERN
CALIFORNIA BY SATURDAY.

.DISCUSSION...THE AIRMASS REMAINED DRY ALONG THE EASTERN RIM INTO
THE WHITE MOUNTAINS AS INDICATED BY SATELLITE PWATER IMAGERY AND THE
LACK OF AFTERNOON CONVECTIVE CLOUDS SHOWING UP THERE. BASED ON THESE
RECENT TRENDS...WILL BACK OFF OR REMOVE POPS FROM THE NORTHEAST
ZONES FOR TONIGHT. THE AIRMASS ACROSS THE REST OF OUR CWA CONTINUED
TO MOISTEN UP EVEN IN THE BOUNDARY LAYER AS EVIDENT IN THE SURFACE
DEWPOINTS REMAINING STEADY OR SLIGHTLY INCREASING WITH THE AFTERNOON
MIXING. RECENT SATELLITE AND RADAR IMAGERY WERE SHOWING A CLUSTER OF
SHOWERS AND THUNDERSTORMS DEVELOPING UNDER A CONFLUENT FLOW ALOFT
THAT STRETCHED WEST TO EAST ALONG THE INTERNATIONAL BORDER TODAY.
THE FLOW AROUND THE ANTICYCLONE CENTERED NEAR THE FOUR CORNERS AND
THE UPPER LOW OVER BAJA WERE PRODUCING THIS REGION OF CONFLUENCE
THAT IS FORECAST TO WEAKEN AND SHIFT FARTHER NORTH TONIGHT.
DEPENDING ON HOW WELL ORGANIZED THE ACTIVITY GETS ALONG THE
BORDER...WE COULD SEE SOME BLOW OUT OR LIGHT RAIN FROM MID LEVEL
DEBRIS CLOUDS AS FAR NORTH AS TUS LATE THIS EVENING AND TONIGHT.
FRIDAY STILL LOOKS FAVORABLE FOR AN INCREASE IN THE AREAL COVERAGE
OF THUNDERSTORMS. THE MAIN REASON FOR THIS THINKING IS THAT THE
MOISTURE SHOULD ALREADY BE IN PLACE BY TOMORROW. THIS MOISTURE
COMBINED WITH BETTER LARGE SCALE FORCING DUE TO A SYSTEM MOVING INTO
NORTHERN CALIFORNIA WHICH FORCES A PIECE OF THE BAJA LOW TO LIFT
NORTHWARD INTO THE AREA. THE FLOW ALOFT IS FORECAST TO WEAKEN AND
BECOME MORE SOUTHWESTERLY OVER THE WEEKEND...SPREADING DRIER AIR
INTO THE STATE FOR AN END TO THE TSTM CHANCES. HOWEVER...GFS
CONTINUED TO KEEP MOISTURE LINGERING OVER OUR FAR EASTERN ZONES
ALONG THE AZ-NM STATE LINE. IF THIS HAPPENS...EVENTUALLY WE MAY NEED
TO HANG ON TO TSTM CHANCES IN AT LEAST THE WHITE MOUNTAINS EARLY
NEXT WEEK. OTHERWISE...IT LOOKS DRY AFTER SATURDAY WITH VERY LITTLE
DAY-TO-DAY CHANGES IN HIGH TEMPERATURES.

.TWC...NONE.

AZZ019-029>035-301400-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
700 AM MST THU MAY 29 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST ARIZONA

.DAY ONE...TODAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

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