Severe Thunderstorm Warning 43, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
230 PM MST THU AUG 16 2001

.SYNOPSIS...HIGH PRESSURE WILL BUILD IN FROM THE WEST THE NEXT FEW
DAYS. THE RESULTING FLOW PATTERN WILL DIMINISH THUNDERSTORM
COVERAGE...ESPECIALLY OVER THE WESTERN DESERTS...WITH DRIER AIR TO
THE NORTH AND DEEPER MOISTURE IN NORTHERN MEXICO. BY EARLY NEXT
WEEK...THE HIGH MOVES EAST OF ARIZONA AND THE FLOW BECOMES FAVORABLE
FOR A RETURN TO NORMAL THUNDERSTORM ACTIVITY.

.DISCUSSION...SLOW DEVELOPMENT UNDER DEBRIS CLOUD TODAY. WE SHOULD
RAMP UP BY LATE AFTERNOON AND EARLY EVENING. WEAKNESS IN THE FLOW ON
THE SOUTH SIDE OF THE DEFORMATION AXIS BETWEEN THE RIDGE BUILDING IN
ACROSS NORTHERN ARIZONA AND THE LOW OVER THE NORTHERN GULF SHOULD
HELP TO FOCUS STORMS. THIS AREA HELPED INFLUENCE COCHISE COUNTY TO
SUSTAIN CONVECTION LAST NIGHT.

WITH THE RIDGE AXIS BUILDING FROM NORTHWEST TO NORTH SWINGING THE
MID LEVEL FLOW MORE EASTERLY WITH TIME...FEATURES (SUCH AS THE
IMPULSE OVER THE NORTHERN GULF OF CA) WILL BE DRAWN TO THE WEST.
WHILE PORTIONS OF THE REST OF THE STATE SEE DRYING...WE SHOULD SEE
SUFFICIENT MOISTURE TO CONTINUE SCATTERED THUNDERSTORM COVERAGE.
EMPHASIS MAY BE MORE ON MOUNTAINS THAN VALLEYS FRIDAY AND
SATURDAY...BUT WITH AFTERNOON HEATING AND SUFFICIENTLY COOL MID
LEVELS WELL CONTINUE TO FEEL THE EFFECTS OF THE MEXICAN MONSOON
UFN. SYNOPTIC SCALE FEATURES BRING A MORE FAVORABLE SOUTHERLY
COMPONENT BACK TO THE FLOW BY EARLY NEXT WEEK. M

.TWC...NONE.

AZZ019-029>035-170700-

SOUTHEAST ARIZONA HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
12 NOON MST THU AUG 16 2001

.SYNOPSIS...HIGH PRESSURE WILL BUILD IN FROM THE WEST THE NEXT FEW
DAYS. THE RESULTING FLOW PATTERN WILL DIMINISH THUNDERSTORM
COVERAGE...ESPECIALLY OVER THE WESTERN DESERTS...WITH DRIER AIR TO
THE NORTH AND DEEPER MOISTURE IN NORTHERN MEXICO. BY EARLY NEXT
WEEK...THE HIGH MOVES EAST OF ARIZONA AND THE FLOW BECOMES FAVORABLE
FOR A RETURN TO NORMAL THUNDERSTORM ACTIVITY.

.DISCUSSION...MORNING UPPER AIR PATTERN SHOWED AN UPPER LEVEL RIDGE
EXTENDING FROM SOUTHERN CALIFORNIA OVER NORTHERN ARIZONA AND AN UPPER
LEVEL LOW OVER SONORA MEXICO. SOUTHEAST ARIZONA LIES BETWEEN THESE
SYSTEMS UNDER A DEFORMATION ZONE. AN AREA OF THUNDERSTORMS MOVED THRU
COCHISE...SANTA CRUZ...AND SOUTHEAST PIMA COUNTY (SOUTH OF TUCSON)
THIS MORNING UNDER THIS DEFORMATION AXIS. MORNING MODELS INDICATE
THAT THIS DEFORMATION AXIS WILL SHIFT A LITTLE TO THE WEST...WITH
MORNING SATELLITE IMAGERY SHOWING THAT THIS IS OCCURRING.

TUCSON MORNING SOUNDING SHOWED ABUNDANT AMOUNT OF MOISTURE BELOW 500
MB BUT THERE HAS BEEN A SIGNIFICANT AMOUNT OF DRYING ABOVE 500 MB
SINCE WEDNESDAY MORNING. PRECIPITABLE WATER VALUES ACROSS SOUTHEAST
ARIZONA ARE BETWEEN 1.25 AND 1.50...WITH HIGHER AMOUNTS FROM TUCSON
WEST.

CLOUD COVER THIS MORNING WILL DELAY THE ONSET OF DEVELOPMENT BUT
EXPECT ISOLATED TO SCATTERED THUNDERSTORMS AGAIN LATER THIS AFTERNOON
AND INTO THE EVENING HOURS BUT WITH THE AREAL COVERAGE A LITTLE
FURTHER WEST THAN WEDNESDAY...MAINLY TO A GLOBE TO SELLS LINE. SOME
STORMS MAY LINGER INTO THE EARLY MORNING HOURS OF FRIDAY.

FLASH FLOODING WILL BE A THREAT FROM CENTRAL PIMA COUNTY EAST ACROSS
EASTERN PIMA COUNTY...SANTA CRUZ AND ALL OF COCHISE COUNTY. AREAS TO
THE NORTH HAVE LESS OF A THREAT. ISOLATED SEVERE NOT OUT OF THE
QUESTION ACROSS CENTRAL AND EASTERN PIMA COUNTY ALONG WITH SANTA
CRUZ COUNTY.

STORM MOTION WILL BE TO THE SOUTHWEST AT 10 TO 15 MPH.