Flash Flood Warning 33, NWS Tucson, AZ

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
230 PM MST MON AUG 9 1999

SYNOPSIS...MONSOON MOISTURE IS SPREADING BACK INTO ARIZONA AND
COMBINED WITH AN UNSEASONABLY STRONG UPPER LOW SYSTEM NEAR THE
CENTRAL CALIFORNIA COAST THERE WILL BE AN UPSWING IN PRECIPITATION
TONIGHT THROUGH WEDNESDAY. BY THURSDAY A DRYER SOUTHWEST WIND FLOW
WILL DEVELOP AS THE UPPER LOW MOVES NORTHEAST INTO WYOMING WITH A
DECREASE IN THE THUNDERSTORM ACTIVITY.

DISCUSSION...PWATER CONTINUES TO INCREASE ACROSS ALL OF THE STATE
THIS AFTERNOON PROMOTING THE ETA AS THE MODEL OF CHOICE. YUM
DEWPOINT HAS GONE UP 6C IN LAST SEVERAL HOURS AND SYNOPTIC SURGE
APPEARS TO BE UNDERWAY. STILL SEEMS TOO LATE TO GET BIG STORMS TODAY
BUT TO THE SOUTH A SERIOUS FLY IS IN THE OINTMENT. AN OVERSIGHT ON
THE EARLIER AFD THERE IS A H3 CIRCULATION MOVING NW UP THE WEST SIDE
OF THE SIERRA MADRE AND IS CURRENTLY CENTERED NEAR CULIACAN. THIS
FEATURE HAS BEEN RESPONSIBLE FOR MAJOR OUTBREAKS LAST TWO NIGHT IN
MEXICO AND STORMS WELL SOUTH OF DUG ARE BEING INFLUENCED BY THIS
SYSTEM. POTENTIAL IS THAT THIS AREA OF STORMS WOULD MOVE INTO
SOUTHEAST ARIZONA LATER TONIGHT. WE WILL ALSO HAVE THE STORMS THAT
ARE DEVLOPING NOW. HAVE UPPED POPS SOME AND PUT HEAVY PRECIP WORDING
IN EASTERN ZONES.

TUESDAY AND WEDNESDAY WILL BE DOMINATED BY THE RESULTANT FLOW
BETWEEN THE RIDGE TO THE EAST AND THE CUTOFF LOW TO THE WEST.
POTENTIAL FOR HEAVY RAIN EVENT EXISTS SINCE DYNAMICS WILL COME INTO
PLAY. STORMS MAY CONTINUE ALL NIGHT IN SOME AREAS TUESDAY NIGHT AND
WEDNESDAY MORNING AS CONVERGENCE ZONE SETS UP AS TROF BEGINS TO LIFT
OUT.

WEATHER SHOULD BE DOWN THURSDAY AS FLOW BECOMES SOUTHWESTERLY WOULD
LIKE TO USE ISOLATED WORDING BUT CHANCE SUFFICES ALSO. DID NOT HAVE
A CHANCE TO LOOK AT ENSEMBLES BUT BELIEVE THE MRF IS TOO STRONG WITH
THE WESTERLY FLOW PATTERN AND WE WILL BE BACK INTO MONSOON BUSINESS
BY SUNDAY. HOLBROOK

.TWC...NONE.