Flash Flood in Arizona, August 17, 2001

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
913 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...SOMEWHAT DISORGANIZED, RATHER ISOLATED, BUT STRONG
TSTMS CONTINUE TO DROP SW THROUGH THE CWA AS THE DEFORMATION AXIS
CONTINUES TO SHIFT W. COCHISE COUNTY GOT WORKED OVER THIS EVENING,
BUT UPPER DIVERGENCE ZONE REMAINS FOCUSED NEAR THE SONORA-ARIZONA-
NEW MEXICO TRIPLE POINT. THE ONE SAVING GRACE IN THE PAST 2-3HRS IS
THAT THE STORMS ARE NOW WORKING OFF THE FASTER MID LEVEL FLOW AND
ARE NOW CRUISING AT 15-20KTS. THATLL KEEP THE THREAT OF FLASH
FLOODING DOWN, ALTHOUGH WE COULD STILL GET SOME GUSTY WINDS. WELL
DO A QUICK UPDATE TO KEEP SLIGHT CHANCE/ISOLATED STORMS GOING FOR
MUCH OF THE NIGHT, EVEN TO THE FAR SE WHERE THE UPPER FORCING IS
STRONGEST.

TOOK A QUICK LOOK AT 00Z ETA AND THERE ARE NO REAL SURPRISES. UPPER
DIVERGENCE BULLSEYE REMAINS OVER SE AZ THROUGH FRI NIGHT, PERHAPS
ENHANCED A BIT AS THE UPPER LOW OVER SONORA MAKES A SLIGHT JOG TO
THE W. INCOMING MOS GUIDANCE, JUST LIKE LAST NIGHT, IS RAMPING UP
POPS FOR FRI AND ESPECIALLY FRI NIGHT. AFTER A BIG NIGHT LIKE THIS
EVENING, WE USUALLY HAVE A DOWN DAY. HOWEVER, IM NOT SURE THAT RULE
WILL WORK THIS TIME AROUND WITH CONTINUED DIVERGENCE ALOFT, DECENT
NE-E FLOW, AND PERHAPS A LITTLE MORE MID LEVEL COOLING. I SUSPECT
THE MOST LIKELY SCENARIO IS A NEAR REPEAT TOMORROW, WITH A SLOW
START AND LIMITED COVERAGE, BUT WITH SOME STRONG STORMS HERE AND
THERE. PYTLAK

.TWC...NONE.