Severe Thunderstorm Warning 20, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
930 PM SAT JUL 22 2000

SYNOPSIS...HIGH PRESSURE WILL REMAIN OVER ARIZONA THROUGH EARLY NEXT
WEEK.  THIS WILL BRING A MOIST MONSOON PATTERN TO THE STATE...WITH A
CHANCE OF MAINLY AFTERNOON AND EVENING THUNDERSTORMS EACH DAY OF THE
FORECAST PERIOD.

DISCUSSION...STRONG STORMS WERE MAKING THEIR WAY ACROSS PORTIONS OF
EASTERN PIMA COUNTY AS OF 9 PM MST. THE STEERING FLOW WAS FROM THE
SOUTHEAST WITH STORMS TRACK TOWARD THE NORTHWEST. LATEST SURFACE
OBSERVATIONS SHOWED RATHER WARM TEMPERATURES IN THE LOWER DESERTS
WITH LARGE TEMP AND DEWPOINT SPREADS. THE EVENING SOUNDING AT TUCSON
SHOWED A FAIRLY DEEP LAYER OF SOUTHEASTERLY WINDS UP TO 20KFT WITH
STEEP MID LEVEL LAPSE RATES. AS A RESULT...THE MAIN THREAT FROM THE
STORMS LATE THIS EVENING WILL BE STRONG DOWNBURST WINDS AND LOCALLY
HEAVY DOWNPOURS. EXPECT THE STORMS AROUND THE TUCSON AREA TO
PROPAGATE NORTHWEST DOWN THE SANTA CRUZ RIVER VALLEY TOWARD PHOENIX.
DUE TO THE ORGANIZATION OF THE STORMS AND THE POTENTIAL FOR HIGH
WINDS...WOULD NOT RULE AT A DUST STORM DEVELOPING ACROSS
SOUTHEASTERN PINAL COUNTY IN THE NEXT FEW HOURS. FOR NOW...CURRENT
FORECAST LOOKS OKAY SO NO UPDATES EXPECTED IN THE SHORT TERM.

.TWC...NONE.