Damaging Wind in Arizona, July 26, 2002

SOUTHEAST ARIZONA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
217 PM MST FRI JUL 26 2002

.SYNOPSIS...HIGH PRESSURE HAS RELOCATED FROM THE FOUR CORNERS INTO
THE SOUTHERN PLAINS. THIS WILL ALLOW A DRIER WESTERLY FLOW ALOFT TO
FILTER INTO THE REGION THIS WEEKEND...LEADING TO A DOWNTURN IN
THUNDERSTORM ACTIVITY. THE HIGH IS THEN EXPECTED TO SHIFT BACK INTO
THE FOUR CORNERS BY EARLY NEXT WEEK...WHICH WILL RESULT IN A RETURN
TO MORE TYPICAL THUNDERSTORM COVERAGE.

.DISCUSSION...AS EXPECTED, STORMS SO FAR HAVE BEEN HUGGING THE
MOUNTAINS AND PRODUCING BRIEF BUT HEAVY RAINS (1-2/HR). THE
RESULTING ANVILS HAVE SPREAD INTO SOME OF THE VALLEYS AND SQUASHED
ADDITIONAL CUMULUS DEVELOPMENT. WE HAVE SEEN NO TENDENCY FOR THE
STORMS TO ORGANIZE OR MOVE INTO THE VALLEYS EN-MASSE, SO WELL
RETAIN CLIMO POPS THIS EVENING DESPITE THE OTHERWISE FAVORABLE
CONDITIONS. WELL ALSO RELUCTANTLY HOLD ONTO CURRENT LOWS, ALTHOUGH
IF THE VALLEYS DONT PICK UP SOME RAIN THIS EVENING AND INSTEAD
REMAIN CLOUDY, EVENING SHIFT MAY HAVE TO RAISE THEM A NOTCH.

DESPITE A PRETTY GOOD GULF SURGE (AT ONE POINT 30KTS JUST BEFORE
12Z), THE DRIER AIR ALOFT IS INVADING AND GRADUALLY WINNING OUT OVER
NW AZ. ONCE THE SURGE BREAKS UP IN THE DEEPENING W FLOW, THE DRIER
AIR WILL START TO MIX DOWN MAKE MORE RAPID PROGRESS INTO OUR CWA.
EVEN IF WE MANAGE TO HOLD ONTO A SHALLOW SURGE OVERNIGHT, THE WEAK
LOW LEVEL FLOW, INCREASINGLY UNFAVORABLE UPPER FLOW, AND GRADUAL
WARMING ALOFT WILL TEND TO REDUCE TSTM COVERAGE. WELL CONTINUE THE
TREND OF MY PREDECESSORS BY LOWERING POPS SAT. WE ORIGINALLY THOUGHT
THAT WED BE NEARLY SHUT DOWN ON SUN, BUT BY THEN THE HIGH OVER THE
SOUTHERN PLAINS WILL BE MOVING BACK INTO POSITION AS THE WEST COAST
TROUGH DEAMPLIFIES A BIT. THUS THE 18Z ETA STARTS BRINGING MOISTURE
BACK IN FROM THE SE AS EARLY AS SUN AFTERNOON. ANOTHER ITEM TO
WATCH, THIS TIME FOR MON, WILL THE THE EASTERLY WAVE OVER THE GULF
OF MEXICO WHICH HAS BEEN CAPTURED UNDERNEATH THE RIDGE. MODELS ARE
NOT IN VERY GOOD AGREEMENT AS TO WHERE IT WILL TRACK, BUT EVEN IF IT
HEADS ACROSS SONORA OUR MID LEVEL FLOW WILL INCREASE OUT OF THE E OR
NE WHILE WE PICK UP SOME MID LEVEL COLD ADVECTION. IN BOTH
INSTANCES, WELL PLAY CLOSE TO THE VEST ON POPS AND LEAN A BIT BELOW
CLIMO UNTIL WE SEE HOW FAST THE MOISTURE WILL REALLY RETURN.
STANDARD MONSOON FORECAST LOOKS GOOD AGAIN BY DAY 4, ALTHOUGH WELL
KEEP THE W IN CHANCE CATEGORY IN CASE THE NEXT TROUGH OFF THE W
COAST ENDS UP BEING A LITTLE STRONGER. PYTLAK

.TWC...NONE.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE TUCSON ARIZONA
0423 PM MST FRI JUL 26 2002

TIME (MST) .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0400 PM    NOGALES                   AZ   FLASH FLOOD
07/26/02   SANTA CRUZ                     7-8 FOOT RISE ON NOGALES WASH IN
                                          LESS THAN AN HOUR. FLOOD
                                          ORIGINATED FROM HEAVY RAINS IN
                                          NOGALES SONORA