Flash Flood in Arizona, July 22, 2002

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
235 PM MST MON JUL 22 2002

.SYNOPSIS...ABUNDANT MOISTURE ENTRENCHED OVER THE AREA WILL PROVIDE
AN UPSWING IN THUNDERSTORMS THIS WEEK AS HIGH PRESSURE STRENGTHENS
OVER THE FOUR CORNERS. AN UPPER LEVEL SYSTEM MOVING WEST FROM NEW
MEXICO WILL ENHANCE THUNDERSTORM DEVELOPMENT TONIGHT. A DECREASE IN
ACTIVITY MAY OCCUR OVER FAR WESTERN SECTIONS TOWARD THE END OF THE
WEEK.

.DISCUSSION...KEMX WSR-88D DETECTS ARC OF SHOWERS/THUNDERSTORMS FROM
VICINITY NOGALES-W TUCSON-ORACLE-CLIFTON. CELLS CONTINUE TO INCREASE
IN COVERAGE ESPECIALLY ACROSS ERN PINAL/GRAHAM/GREENLEE COUNTIES.
ECHOES HAVE RECENTLY DEVELOPED ACROSS EXTREME SE COCHISE COUNTY.
MOVEMENT HAS BEEN TOWARD THE NW AROUND 15 KTS. CONVECTION APPEARS TO
BE DEVELOPING IN AREA OF DIVERGENCE ALOFT ASSOCIATED WITH CYCLONIC
CIRCULATION OVER CENTRAL GULF CA AND AHEAD OF INVERTED TROF FEATURE
OVER SE NM. WILL OPT TO CONTINUE FLASH FLOOD WATCH UNTIL 23/04Z FOR
BURN AREAS OF ZONES 29/33/34/35. APPEARS THAT NORMAL-GRADE MONSOON
ACTIVITY TO PREVAIL TONIGHT AS INVERTED TROF SYSTEM ENCROACHES ON
AREA. THUS LOCALLY HEAVY RAINS COULD OCCUR HOWEVER DOWNSIDE TO
SIGNIFICANT RAINS WILL BE EXPECTED STEADY MOVEMENT OF CELLS. UPPER
HIGH PROGGED TO BUILD VICINITY FOUR CORNERS REGION NEXT FEW DAYS.
ELY FLOW TO PREVAIL AT ALL LEVELS ACROSS SE AZ THROUGH AT LEAST
MID-WEEK THUS SHUNTING DEEPER MOISTURE FIELD FROM NM WWD. WILL OPT
FOR NORMAL-GRADE MONSOON ACTIVITY THROUGH WED. SCATTERED SHOWERS/
THUNDERSTORMS TO CONTINUE AND GIVEN ABUNDANCE OF MOISTURE BELIEVE
THAT ACTIVITY MAY PERSIST WELL INTO THE NIGHT. THUS WILL REFLECT
ACCORDINGLY IN FORECAST AND EFFECTIVELY ELIMINATE EVENING MENTION OF
PRECIPITATION VERBAGE FROM TUS EASTWARD. EXTENDED AVN/GFS DEPICTS
PROSPECT OF INCREASED ACTIVITY FRI WHERE MID/UPPER FORCING VIA
OMEGA/Q-VECTOR/DIVERGENCE FIELDS BECOME MORE PRONOUNCED. THUS FRI
MAY BE UP-DAY ASSUMING PERFECT PROG SCENARIO BUT WOULD NOT PUT TOO
MUCH FAITH IN THOSE DETAILS AT THIS TIME. WILL MAINTAIN SCATTERED
MAINLY AFTERNOON/EVENING THUNDERSTORMS AREAWIDE DURING EXTENDED
PERIOD. DAYTIME MAX TEMPS EXPECTED TO REMAIN CLOSE TO SEASONAL
NORMALS FOR LATE JULY.  BF

.TWC...FLASH FLOOD WATCH FOR BURN AREAS UNTIL 9PM ZONES 29/33/34/35.

AZZ019-029>035-240700-
SOUTHEAST ARIZONA HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1205 PM MST TUE JUL 22 2002

.SYNOPSIS...THE PROBABILITY FOR PRECIPITATION IN EXCESS OF ONE INCH
AND SEVERE THUNDERSTORM WILL BE NEAR CLIMATOLOGY IN THE EAST AND
ABOVE CLIMATOLOGY WEST.

.DISCUSSION...LOTS OF MOISTURE AVAILABLE TODAY AND THUNDERSTORMS
WILL BE PLENTIFUL...MAJOR LIMITING FACTOR IS SPEED OF MOTION AND IF
WE CAN GET ANY ORGANIZATION TO THE STORMS. GENERALLY STRONGER EAST
WINDS ALOFT FAVOR LOW DESERTS WEST OF TUCSON FOR BOTH SEVERE AND
HEAVY RAIN SCENARIO. SEVERE SEEMS LESS LIKELY...EXCEPT TOWARDS
PICACHO AND WESTERN AREAS. PHOENIX SOUNDING THIS MORNING LOOKS TO BE
A SEVERE WEATHER SOUNDING...WIND SPEEDS ARE EVEN LOWER THERE FOR
SLOWER STORM MOTION...SO BEST THREAT OF SEVERE IN OUR WARNING AREA
WOULD BE NORTHWEST OF A LINE FROM ORGAN PIPE...TO SELLS TO PICACHO
TO WINKLEMAN.

AS FOR HEAVY RAIN...BEST CHANCE IS FARTHER NORTH AND WEST...ONCE
AGAIN DUE TO SLOWER STORM MOTION AND A CHANCE FOR STORMS TO
ORGANIZE. BUT WITH HIGH WATER VALUES AVAILABLE FOR STORMS ANY
LOCATION IN SOUTHEAST ARIZONA MAY SEE LOCAL ONE INCH RAINS.

STORMS THAT HAVE ALREADY FORMED THIS MORNING OVER THE SANTA RITA
MOUNTAINS HAVE SHOWN A MOTION OF NORTHWEST AT 20 MPH.

NOTE THE TUCSON DOPPLER RADAR IS STILL NOT IN OPERATION DUE TO
COMMUNICATION LINE PROBLEMS...WE WILL BE DEPENDING ON OTHER RADARS
AND SATELLITE INFORMATION TO DETERMINE BOTH SEVERITY OF STORMS AND
FLASH FLOOD POTENTIAL.

AZZ019-029>035-230700-
SOUTHEAST ARIZONA HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE TUCSON AZ
1210 PM MST MON JUL 22 2002

...FLASH FLOOD WATCH FOR BURN AREAS IN COCHISE...SANTA CRUZ...
EXTREME SOUTHEAST PINAL...AND EXTREME NORTHEAST PIMA COUNTIES FROM
NOON UNTIL 9 PM MST...

.SYNOPSIS...THE PROBABILITY FOR PRECIPITATION IN EXCESS OF ONE INCH
AND SEVERE THUNDERSTORM WILL BE NEAR CLIMATOLOGY EAST OF A LINE FROM
SAN MIGUEL TO TUCSON TO KEARNY...BUT BELOW CLIMATOLOGY ELSEWHERE.

.DISCUSSION...THE FAVORED AREA FOR THUNDERSTORM ACTIVITY TODAY WILL
BE ACROSS THE SOUTHEAST CORNER OF ARIZONA...MAINLY EAST OF A LINE
FROM SAN MIGUEL TO TUCSON TO KEARNY. AN AREA OF MID-LEVEL
CONVERGENCE WILL CONTINUE TO INCREASE TODAY OVER THIS AREA AS A
TROUGH OVER SOUTH-CENTRAL ARIZONA...CLEARLY SEEN IN THE VISIBLE
SATELLITE IMAGERY...BEGINS TO LIFT NORTHEAST AND A MID-LEVEL HIGH
OVER COLORADO MOVES SOUTHEAST. THIS WILL INTERACT WITH THE DEEPER
MOISTURE RESIDING EAST OF TUCSON TODAY TO ENHANCE THUNDERSTORM
DEVELOPMENT...ESPECIALLY OVER THE MOUNTAINS BY EARLY AFTERNOON.
THESE STORMS WILL THEN CONSOLIDATE INTO CLUSTERS BY LATE IN THE
AFTERNOON AND MOVE WEST INTO THE DESERTS AND VALLEYS BY EVENING.

THE MORNING TUCSON UPPER AIR BALLOON SOUNDING INDICATED THAT THE
WINDS ALOFT HAVE INCREASED OVER THE PAST 24 HOURS. IN FACT...STORM
MOTION WILL BE TOWARDS THE WEST SOUTHWEST AT 20 MPH. THIS FASTER
STORM MOTION WILL KEEP THUNDERSTORMS FROM STAYING IN ONE PLACE FOR
ANY SIGNIFICANT LENGTH OF TIME. THIS WILL SERVE TO REDUCE THE
OVERALL THREAT FOR RECEIVING PRECIPITATION IN EXCESS OF ONE INCH.

HOWEVER...A FEW STORMS WILL BE CAPABLE OF PRODUCING AN INCH OF RAIN
IN A SHORT PERIOD OF TIME. SUCH HEAVY RAINS WILL QUICKLY RUNOFF IN
AREAS THAT WERE BURNED EARLIER THIS SUMMER...AND MAY RESULT IN BOTH
FLASH FLOODS AND MUDSLIDES. THEREFORE...A FLASH FLOOD WATCH REMAINS
IN EFFECT FOR BURNED AREAS FROM NOON UNTIL 900 PM MST.

THE AMPLE MOISTURE AT BOTH LOW AND MID-LEVELS WILL DECREASE THE
THREAT FOR STRONG THUNDERSTORM OUTFLOWS. THEREFORE...THE THREAT FOR
A SEVERE THUNDERSTORM WILL BE BELOW CLIMATOLOGY ACROSS ALL OF
SOUTHEAST ARIZONA. ALTHOUGH THESE OUTFLOWS MAY NOT REACH SEVERE
LEVEL CRITERIA...GUSTS TO 40 MPH WILL ACCOMPANY THE STRONGER STORMS.