Flash Flooding and Damaging Wind in Arizona, August 13, 2001

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
240 PM MST MON AUG 13 2001

.SYNOPSIS...A LOW PRESSURE SYSTEM OVER CHIHUAHUA WILL MOVE NORTHWEST
INTO ARIZONA TONIGHT. THIS FEATURE IS BEING STEERED BY AN AREA OF
HIGH PRESSURE CENTERED NEAR THE FOUR CORNERS REGION. THIS HIGH WILL
REMAIN SOMEWHAT STATIONARY THE NEXT SEVERAL DAYS...KEEPING
CONSIDERABLE MOISTURE OVER THE REGION.

.DISCUSSION...THE LACK OF MOISTURE WILL DEFINITELY NOT BE A MISSING
INGREDIENT FOR SHOWERS AND THUNDERSTORMS TODAY. LATEST SURFACE
OBSERVATIONS WERE SHOWING DEWPOINTS IN THE 60S TO AROUND 70 ACROSS
THE REGION...AND SATELLITE ESTIMATED PWATER VALUES WERE AROUND 1.75
FROM TUS WEST AND NEAR 1.25 TO THE EAST. DETAILS IN THE UPPER FLOW
PATTERN WERE RATHER COMPLICATED WITH ARIZONA IN BETWEEN TWO AREAS OF
HIGH PRESSURE...ONE OVER THE EASTERN PACIFIC AND THE OTHER OVER NEW
MEXICO INTO TEXAS. THE INVERTED TROUGH THAT MOVED INTO THE STATE
SATURDAY WAS CAUGHT IN BETWEEN THESE TWO CIRCULATIONS OVER WESTERN
ARIZONA. LATEST MODELS SHIFT THIS TROUGH A LITTLE EAST TODAY WITH
THE TAIL END OF IT PROVIDING SOME WEAK LARGE SCALE LIFT OVER
SOUTHEAST ARIZONA THIS EVENING. THE OTHER FEATURE TO WATCH FOR WAS
A WAVE OVER NORTHERN MEXICO AND APPEARS TO BE MAKING A NORTHWESTERLY
TRACK TOWARD SOUTHEAST ARIZONA AND SOUTHWEST NEW MEXICO. LATEST
MODELS PICK UP ON THIS FEATURE AT LEVELS ABOVE THE STANDARD 500MB
LEVEL AND MOVE IT INTO OUR CWA BY TUESDAY MORNING. SOUTHEASTERN
ARIZONA SHOULD SEE SOME INFLUENCE FROM THIS WAVE AS EARLY AS THIS
EVENING. THE ONLY LACKING INGREDIENT FOR STRONG THUNDERSTORMS WILL
BE THE INSTABILITY. CURRENT AIRMASS APPEARS TO BE TOO WARM ALOFT...
RESULTING IN WEAK CAPE ESPECIALLY FROM TUS WEST. HOWEVER...RECENT
SATELLITE IMAGERY WAS SHOWING A SIGNIFICANT THINNING OF THE DEBRIS
CLOUDINESS OVER SOUTHEAST ARIZONA. THUS...CURRENT THINKING IS THAT
WE SHOULD SEE ENOUGH DAYTIME HEATING COUPLED WITH OROGRAPHIC AND
LARGE SCALE FORCING TO PRODUCE NUMEROUS SHOWERS AND THUNDERSTORMS
THIS AFTERNOON AND EVENING. LOCALLY HEAVY RAINFALL WILL BE THE MAIN
THREAT TODAY...BUT STRONG WINDS FROM WET DOWNBURST ARE NOT OUT OF
THE QUESTION TOO. BEYOND TODAY...NOT ENOUGH CHANGE IN THE MOISTURE
TO WARRANT ANY TREND IN THUNDERSTORM ACTIVITY. THUS...STANDARD
SUMMER SEASON FORECAST LOOKS ON TRACK.

.TWC...NONE.

AZZ019-029>035-140700-

SOUTHEAST ARIZONA HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1155 AM MST MON AUG 13 2001

.SYNOPSIS...FEATURES COMING TOGETHER TO ENHANCE STORMS ACROSS
CENTRAL AND NORTHERN ARIZONA TODAY. WELL HAVE TO RELY ON PLENTY OF
MOISTURE AND AFTERNOON HEATING FOR A TYPICAL CONVECTIVE AFTERNOON
AND EVENING COVERAGE WISE AND AN EMPHASIS ON WETTER THAN NORMAL
STORMS FOR SOUTHEAST ARIZONA.

.DISCUSSION...PRECIPITABLE WATER RANGES FROM ABOUT 1.3 INCHES FAR
EAST TO ABOUT 1.9 INCHES WEST...SO PLENTY OF MOISTURE. DEBRIS CLOUD
BROKE UP NICE AND EARLY...SO PLENTY OF SUNSHINE. CONVECTIVE
TEMPERATURES WILL BE REACHED EARLY AND OFTEN. NOT MUCH IN THE WAY OF
A SOLID ORGANIZATIONAL PROFILE OR FOCUS/TRIGGER (AT LEAST IN OUR
NECK OF THE WOODS FOR TODAY). STORM MOVEMENT SHOULD BE JUST BRISK
ENOUGH TO HELP EASE FLASH FLOODING CONCERNS A LITTLE.

WERE LOOKING AT NEAR NORMAL SEVERE THUNDERSTORM CONCERNS...A
TYPICAL DAY WHERE ANY GIVEN STORM COULD PRODUCE LOCALLY SEVERE
CONDITIONS BUT NOTHING WIDESPREAD. FLASH FLOODING IS A LITTLE MORE
OF A CONCERN WITH SUCH NICE PRECIPITABLE WATER VALUES ACROSS MUCH OF
THE AREA. CLIMATOLOGY FAVORS EASTERN PORTIONS...BUT THE HIGHER
PRECIPITABLE WATER VALUES OUT WEST WILL HELP EVEN THIS NORMAL
EMPHASIS OUT TO INCLUDE WESTERN AREAS AS WELL.

STORM MOVEMENT WILL BE GENERALLY TO THE NORTH AROUND 10 MPH.

MEYER