Severe Thunderstorm Warning 41, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
230 PM MST WED AUG 15 2001

.SYNOPSIS...HIGH PRESSURE WILL BUILD IN FROM THE WEST COAST THE
REMAINDER OF THE WEEK. THE RESULTING FLOW WILL GENERALLY DIMINISH
THUNDERSTORM COVERAGE...PARTICULARLY WEST OF TUCSON. BY EARLY NEXT
WEEK...THE HIGH MOVES EAST OF ARIZONA AND THE FLOW BECOMES FAVORABLE
FOR A RETURN TO NORMAL THUNDERSTORM ACTIVITY.

.DISCUSSION...AS EXPECTED THE FLOW HAS BECOME NORTHEASTERLY WITH US
ON THE EAST SIDE OF THE NOW DOMINANT WEST COAST RIDGE. WEAK
DEFORMATION ZONE STRETCHING AND SETTLING INTO SOUTHEAST
ARIZONA...BUT RAPIDLY BECOMING NEUTRAL. DRY AIR TRYING WRAP IN FROM
THE NORTH AND NORTHEAST...BUT IT LOOKS LIKE WERE HOLDING ON TO
MOISTURE ACROSS MOST OF THE AREA. 10 TO 15KT STEERING FLOW NICE FOR
STORMS TO COME OFF TERRAIN (OUTFLOW FROM THE RIM?)...BUT EARLY
AFTERNOON DEVELOPMENT IS BEHIND WHAT ONE MIGHT EXPECT WITH THE
AMOUNT OF MOISTURE STILL AVAILABLE AND CAPE VALUES.

EVEN SOUTHEAST ARIZONA SHOULD SEE SOME DRYING EFFECTS TOMORROW AS
UPSTREAM DOESNT HAVE MUCH TO OFFER WHILE WERE ON THE WRONG SIDE OF
THE RIDGE AXIS. WELL STILL SEE CONVECTION...BUT MORE EMPHASIS WILL
BE PLACED ON MOUNTAIN DEVELOPMENT IN THE FORECAST...AND FLASH
FLOODING CONCERNS WILL DIMINISH.

SYNOPTIC FEATURES WILL ONCE AGAIN BE FAVORABLE FOR INCREASING
COVERAGE OF THUNDERSTORMS BY EARLY NEXT WEEK. AT ANY
RATE...NORTHWEST MEXICO WILL REMAIN ACTIVE...AND OUTFLOWS FROM
COMPLEXES WILL COUNTER MUCH OF ANY ATTEMPTED DRYING TREND THIS FAR
SOUTH. M

.TWC...NONE.

AZZ019-029>035-160700-

SOUTHEAST ARIZONA HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1155 AM MST WED AUG 15 2001

.SYNOPSIS...EXPECT A STRONG THUNDERSTORM DAY TODAY...FOLLOWED BY
HIGH PRESSURE BUILDING IN FROM WEST TOMORROW. THE RESULTING FLOW
WILL GENERALLY DIMINISH THUNDERSTORM COVERAGE...PARTICULARLY WEST OF
TUCSON. BY EARLY NEXT WEEK...THE HIGH MOVES EAST OF ARIZONA AND THE
FLOW BECOMES FAVORABLE FOR A RETURN TO NORMAL THUNDERSTORM ACTIVITY.

.DISCUSSION...MODELS STILL SHOWING STRONG THUNDERSTORMS WILL DEVELOP
TO THE NORTH AND MOVE SOUTH AND SOUTHWEST ACROSS THE AREA THIS
AFTERNOON. LOTS OF MINOR ISSUES...FIRST IS HOW MUCH MOISTURE CAN WE
HOLD ONTO TODAY. DRYING NOTED ON PRECIPITABLE WATER FIELDS IS DUE TO
MID LEVEL MOISTURE BUT BELOW 5000 FEET THERE IS STILL PLENTY OF
MOISTURE. THIS ACTUALLY PLAYS INTO INCREASED SEVERE THREAT SINCE DRY
MID LEVELS WILL HAVE AN ACCELERATING EFFECT...IN THE VERTICAL..ON
STORMS. MODELS ALSO SHOW SEVERAL DEGREES OF COOLING WHICH WILL MAKE
ATMOSPHERE MORE UNSTABLE. OF MORE IMPORTANCE IS THAT WE ARE UNDER
THE ANTICYCLONIC CURVATURE AT THE CIRRUS LEVEL THAT WILL MAKE IT A
MORE FAVORABLE ENVIRONMENT FOR ORGANIZED THUNDERSTORMS AND NOT JUST
THE RANDOM EVENT WE HAD LAST NIGHT. THIS SAME TYPE OF CURVATURE WAS
EVIDENT IN THE STORMS WHICH AFFECTED PHX AND THE WESTERN DESERTS
LAST NIGHT. STORM SPEED MAY BE 15 MPH WHICH USUALLY WOULD
ELIMINATE FLASH FLOODING BUT STORMS MAY BE LARGE WHICH WILL EQUALLY
OFFSET THE SPEED PROBLEM. SINCE THERE IS LESS MOISTURE TO THE NORTH
STORMS MAY NOT BE IMPRESSIVE LOOKING UNTIL THEY GET FARTHER SOUTH SO
INCREASED THREAT IS FROM TUCSON TO WILLCOX AND FARTHER SOUTH.

STORM MOTION WILL BE TO THE SOUTH AND SOUTHWEST AT 15 MPH.

HOLBROOK